WO2015177389A1 - Device and method for measuring the impedance of an energy storage element - Google Patents

Device and method for measuring the impedance of an energy storage element Download PDF

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Publication number
WO2015177389A1
WO2015177389A1 PCT/ES2015/070387 ES2015070387W WO2015177389A1 WO 2015177389 A1 WO2015177389 A1 WO 2015177389A1 ES 2015070387 W ES2015070387 W ES 2015070387W WO 2015177389 A1 WO2015177389 A1 WO 2015177389A1
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Prior art keywords
voltage
current
vbat
acond
signal
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PCT/ES2015/070387
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Spanish (es)
French (fr)
Inventor
José LÓPEZ DOMÍNGUEZ
Francisco José PÉREZ NIETO
José Luis JIMÉNEZ LÓPEZ
María del Mar GARCÍA MAESTRE
Alfredo PÉREZ VEGA-LEAL
Diego RODRÍGUEZ RAMOS
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Instalaciones Inabensa, S.A.
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Publication of WO2015177389A1 publication Critical patent/WO2015177389A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]

Definitions

  • the present invention is encompassed in the field of electrical devices, and more specifically in the measurement of impedance of such electrical device by spectroscopy.
  • an impedance spectroscopy measurement system allows the experimental measurement of the impedance of a device under test -DUT (device under test) - either passive or active, as is the case of a battery, in the domain of the frequency.
  • the principle of operation is to excite that device under DUT test with a current with a certain spectral content (typically sinusoidal or step sweep) and measure the voltage variations produced in DUT terminals. The relationship between the two is impedance.
  • the most widespread method of impedance measurement is frequency scanning using sine current stimuli (galvanostatic method). This consists in applying a sinusoidal disturbance at different frequencies, studying the response of the same for each of them. An impedance value for each frequency value is thus obtained, and a diagram representing the impedance spectrum can be constructed.
  • the limits of the frequency range, the number of points and the choice of a linear or logarithmic sweep depend on the system to be studied, and are set with a certain criterion so that the Results provide the maximum possible information.
  • the device and the measurement procedure of the present invention solve the problem of loss of resolution posed with existing systems employing signals of entry into the frequency domain, stimulating the energy storage element with an input signal in the time domain, which is initially known in the frequency domain; the continuous part of the signal measured in time is eliminated and only the behavior of the alternating component of the signal is studied, achieving a higher resolution as far as in the case of state of the art devices.
  • a first aspect of the invention relates to an impedance measuring device of an energy storage element, comprising:
  • analog to digital conversion means for converting said conditioned voltage and current signals, Vbat_acond, lbat_acond, into a digitized voltage V (t) and current l (t) signals; Y,
  • processing and control means configured to:
  • the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a high-pass filter to eliminate the continuous component of at least the measured voltage signal.
  • These conditioning means preferably further comprise at least one amplifier stage for amplifying the alternating component of the voltage signal not blocked by the high-pass filter. This way you they condition the voltage and current signals measured in the energy storage element to the dynamic range of the analog-digital conversion means by first eliminating the continuous component of the measured signal, centering it (offset) to the input range of said conversion means and amplifying it For higher resolution.
  • the cut-off frequency of said high-pass filter preferably depends on the frequency spectrum of the current stimulus i (f), which also depends on the frequency range to be observed.
  • the frequency range used that gives useful information is in the range 0.01 Hz-2 kHz. This range of interest defines the cutoff frequency of the high pass filter (in this case, 0.01 Hz).
  • the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a high-pass filter to eliminate the continuous component of at least the measured current signal.
  • the device comprises:
  • the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a low-pass filter to obtain an average voltage value Vprom of the measured voltage signal Vbat, and a comparator - such as an amplifier - to obtain the conditioned voltage signal Vbat_acond as a comparison of said voltage value Vprom and measured Vbat.
  • the low-pass filter is formed by a resistor and several capacitors connected in parallel; the low-pass filter is initialized by two transistors - such as, for example, MOS transistors - and a set of resistors; said measured Vbat voltage signal is passed through the low-pass filter to obtain an average voltage value Vprom; and - said average voltage Vprom is compared in the comparator to the measured voltage signal Vbat, the comparator output being the conditioned voltage signal Vbat_acond.
  • the low-pass filter is formed by a resistor and several capacitors connected in parallel; the low-pass filter is initialized by two transistors - such as, for example, MOS transistors - and a set of resistors; said measured Vbat voltage signal is passed through the low-pass filter to obtain an average voltage value Vprom; and - said average voltage Vprom is compared in the comparator to the measured voltage signal Vbat, the comparator output being the conditioned voltage signal Vbat_acond.
  • the means for adjusting this current signal in the time domain at a charge level of the energy storage element and, to excite the energy storage element with this current signal adjusted in the time domain preferably comprises a current source.
  • the current source preferably comprises a transistor (it can be an nMOS transistor) with a resistor connected between the drain of the transistor and a supply voltage, and a resistor connected between a source of the transistor and a grounding; and also comprises an amplifier connected to a transistor gate in negative feedback with the source voltage.
  • the means for generating a current stimulus i (f) in the frequency domain with a given spectral content and the means for transforming said current stimulus i (f) in the frequency domain to a current signal in The time domain are preferably integrated in the processing and control means, which can be a microprocessor or a digital signal processor.
  • the spectral content of the current stimulus is configurable at different frequencies so that different parts of the DUT can be analyzed whose correct operation against failure is observed at respective frequencies.
  • the device of the invention provides a suitable input stimulus or signal at all times (greater signal amplitude for the lower frequencies), also achieving energy savings in the supply of said stimulus. This is achieved by transforming the frequency signal to the time domain by means of an electronic step of adjusting the current stimulus.
  • the impedance measuring device and method of an energy storage element of the invention calculates the impedance of said energy storage element in the frequency domain but applying a transformed stimulus from the frequency domain to the time domain, and initially measuring its electrical response in terms of voltage and current in the time domain to finally pass it over a wide range of frequencies, thus achieving an electrical model of the battery in the frequency domain.
  • the invention has the added advantage that it does not damage the energy storage element thanks to the control of the amplitude and frequency stimulus (not generating stimuli at frequencies that may be harmful to health);
  • the device is easy to use and the data obtained can be analyzed using an equivalent circuit model.
  • the measurement of the impedance of the energy storage element by means of the device of the invention allows to know the state of the same, being able to carry out the corresponding control or monitoring and detecting possible failures, such as, for example, oxidations in contacts.
  • Another aspect of the invention relates to an impedance measurement method of an energy storage element, comprising:
  • Vbat measure voltage and current signals
  • Ibat in the time domain of the energy storage element and condition said measured signals to conditioned voltage and current signals, Vbat_acond, lbat_acond to a dynamic range of analog to digital conversion means ;
  • the step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond preferably comprises eliminating the continuous component of at least the measured Vbat voltage signal.
  • This continuous component of the measured Vbat voltage signal can be eliminated by a high-pass filter.
  • the alternating component of the voltage signal not blocked by the high-pass filter is preferably amplified.
  • the step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond may comprise obtaining an average voltage value Vprom of the measured voltage signal Vbat, and obtaining said conditioned voltage signal Vbat_acond by comparing said Average voltage value Vprom with the measured voltage signal Vbat.
  • the average voltage value Vprom is preferably obtained by passing the measured voltage signal Vbat through a low-pass filter and the comparison is made with an amplifier.
  • the process of the invention further comprises a step additional to interpret the data obtained from Z (f) with patterns and diagnose the energy storage element.
  • Figure 1 schematically shows the different elements of the impedance measuring device of the invention.
  • Figure 2 shows a detailed diagram of a first possible embodiment of the conditioning of the voltage signal measured at battery terminals.
  • Figure 3 shows a detailed scheme of a first possible embodiment of the conditioning of the measured current signal of the battery.
  • Figure 4 shows a detailed diagram of a second possible embodiment of the conditioning of the voltage signal measured at battery terminals.
  • a circuit is not necessary to condition the measured current signal of the battery, since it is already at a low frequency.
  • Figure 5 shows a diagram of the current source responsible for adjusting the current stimulus generated by the DSP or microprocessor to the charge demanded by the battery in every moment, and excite with said current adjusted the battery.
  • Figure 6 shows schematically the conditioning of the voltage signal measured at the battery terminals (which in Fig. 1 has been schematically represented as a voltmeter 2) and which can be seen in more detail in Figures 2 and 4 in its two preferred embodiments.
  • Figure 7 shows schematically the measurement of the battery's current signal (which in Fig. 1 has been schematically represented as an ammeter 3), and which can be seen in more detail in Figure 3.
  • FIG. 1 A general scheme of the impedance measuring device 100 of a device under test is shown in Figure 1, in this case an electrical storage element such as a battery 1.
  • the impedance measuring device of the invention 100 comprises a microprocessor 7, which can also be a digital DSP signal processor, which generates a stimulus consisting of a current signal i (f) in the frequency domain with a given spectral content.
  • This current signal is transformed from the frequency domain to the time domain by a reverse Fourier transform (IFFT) and a digital-analog converter 6.
  • IFFT reverse Fourier transform
  • a digital-analog converter 6 Using a current source 4 (see Fig. 5) this current signal is set resulting in the time domain i (t) at the necessary charge of the battery 1 at each moment.
  • this includes two measuring and conditioning circuits of the instantaneous measured voltage and current signals of the battery 1.
  • These circuits have been schematically represented in Figure 1 as a voltmeter 2 and an ammeter 3 connected in terminals of and in series with the battery 1, respectively.
  • the signals are conditioned to the dynamic range of an ADC 5 analog-digital converter, where the signals are digitized before entering the microprocessor 7, where they are transformed the voltage and current signals to the domain of the frequency by eg, direct Fourier transformation (FFT), to determine the impedance of the battery in the corresponding frequency range.
  • FFT direct Fourier transformation
  • the measurement and conditioning circuit of the voltage signal or voltmeter 2 does not measure scaled voltages as in the state of the art devices (the measured voltage is at the intermediate point between two resistors), but measures a filtered voltage or band of tension interest. This is because only the alternating part (discarding the continuous component) of the battery voltage signal 1 is of interest.
  • For filtering the voltage signal there are two possible preferred embodiments of the measurement and conditioning circuit of the voltage signal or voltmeter 2.
  • the Vbat voltage signal is a high voltage signal that is conditioned by eliminating its continuous component for the frequency range to be analyzed (in the example shown for frequencies greater than 10 mHz); for this, the voltage signal is passed through a high-pass filter formed by a capacitor C23 and a resistor R24 connected to ground, in order to fix its alternating component from 10 mHz before passing through a first amplifier 21 a.
  • a voltage divider of Vbat is included formed by the resistors R1, R2 and R3; the gain of the first amplifier 21 a is controlled by means of a potentiometer R4 connected in series with a resistor R5 that is connected to the negative input of the first amplifier 21 a, as well as by a feedback resistor R6 connected between the output of the first amplifier 21 a and its negative entry.
  • the first amplifier 21 a is powered by voltages of +12 V and -12 V, with respective capacitors C10 and C1 1 grounded to avoid noise.
  • a second amplifier 21 b By means of a second amplifier 21 b, the amplification of the alternating signal that has not been blocked is performed, the gain of this second amplifier being controlled by another potentiometer R7 connected in series with a resistor R8, which is connected to the negative input of the second amplifier 21 b, together with a feedback resistance R9. Similar to the first amplifier 21 a, the second amplifier 21 b is powered by voltages of +12 V and -12 V, with respective capacitors C5 and C4 grounded and used to avoid noise.
  • the output signal which is the voltage signal of the Vbat_acond battery already conditioned, is centered in the input range of the DAC 5 analog-digital converter (2.5 V), maximizing the dynamic range of the amplified signal and increasing the signal to noise ratio (SNR) in this voltage signal of the already conditioned Vbat_acond battery.
  • this voltage signal conditioning circuit has a high gain, since the current requirements are small in relation to the capacity of the batteries to facilitate intensity-power which translates into a small response in form of voltage drop. Therefore, two amplifications 21 a and 21 b are included to achieve this objective, and by modifying the values of the resistors R4-R5-R6 and R7-R8-R9, the gain value of each amplifier is controlled.
  • a measurement and conditioning circuit of the Ibat current signal measured in battery 1 is shown in Figure 3 (very similar to the measurement and conditioning circuit of the Vbat voltage signal measured in battery 1).
  • the Ibat current signal is a quasi-known signal since it is nothing more than the adaptation of the current stimulus, it must be measured because there can always be distortions when generating the signal. Since a filter must be introduced for the measurement and conditioning of the voltage part that is going to introduce a defined distortion, this same filter is applied to condition the current part (the measurement that is obtained from impedance is V / l, if V distortions are applied, they apply to I).
  • This stage of current conditioning in parallel to the voltage conditioning makes the measurements of both signals more similar to each other in relation to possible noise interference and non-linearities of the device and the conditioning itself.
  • this current conditioning a high-pass filter is also introduced, so that both branches are affected by the same type of frequency filter. While it should be noted that the voltage signal conditioning circuit has a higher gain than the current signal conditioning circuit gain.
  • FIG. 4 A second possible preferred embodiment of the conditioning of the voltage signal Vbat measured in terminals 1 a-1 b of the battery 1 is shown in Figure 4.
  • the circuit has a low-pass filter 50, which only lets the signal with a frequency below 10 mHz.
  • the two MOS transistors 53 and the resistors R shown in this Figure 4 serve to preload five capacitors C52 connected in parallel that make up the low-pass filter 50 (to initialize the filter), where the resistor 51 is the input resistance of the filter.
  • the battery 1 has oscillations depending on the current
  • the average voltage value Vprom is obtained, the value of which can be checked through a probe 60 coaxial
  • the door of the MOS transistor 53 is connected to a digital output leg of the microprocessor 7. This leg controls the activation status of the MOS.
  • This low-pass filter 50 adjusts to the frequency range to be measured.
  • This average voltage value Vprom depends on battery 1, among others, on its charge level. In the case of electric vehicle batteries, 400V battery voltages are typical. Therefore, in both nodes (Vbat and Vprom) the voltage values make it necessary to carefully choose both the amplifier 21 and the transistor 53. In this way, the instantaneous value of the voltage Vbat is inserted into the terminals of the battery 1 in the amplifier 21 which is compared with the average voltage value Vprom, thus obtaining the variation in the time of the voltage in the battery 1 at the output of the amplifier 21, which is the voltage signal of the battery already conditioned Vbat_acond to be introduced in the analog-digital converter CAD 5.
  • R10 has the function of adjusting the gain of the amplifier 21.
  • a value of R10 100 kohm is chosen to obtain a gain of 10.
  • the continuous part of the voltage signal measured at terminals 1 a-1 b of the battery 1 is eliminated to have a voltage measurement within a given range.
  • This range is given by the dynamic range of the analog-to-digital converter DAC 5.
  • the direct current signal occupies more bits than that of the alternating signal.
  • Figure 5 shows the current source 4 that provides the current or excitation stimulus to the battery 1. It is a voltage controlled current source 4, so that if the voltage is increased the current is increased and if the voltage at its terminals is reduced in the same way the current is reduced. In this way the current source 4 adjusts the signal generated by the microprocessor 7 or DSP to demand a given current stimulus from the battery.
  • This step of adjusting the signal generated by the microprocessor 7 in the current stimulus demanded from the battery 1 includes a transistor nMOS 44 that modulates this current stimulus and is controlled by the voltage of its source Vs (point 44s). Transistor nMOS 44 opens or closes depending on the voltage.
  • a resistance R42 of 10 ohm is inserted into the drain (point 44d) of the transistor 44.
  • the resistor R43 of 1 ohm connected between the source of the transistor and earth allows the current value to be sensed, adjusting the output of the amplifier 41 to the value necessary for the current to follow the setpoint (output of CDA 6).
  • the conditioning of the voltage signal measured in the battery of the first embodiment shown in Figure 2 is shown schematically.
  • the measured voltage signal Vbat is passed through a high-pass filter formed by a capacitor C23 of 10 mF and an R24 resistor of 1.6 kohm grounded;
  • This high-pass filter lets the high frequency pass: it rejects the direct current and lets the signal pass from a frequency, in this particular example from 10 mHz.
  • the amplifier 21 acts as a voltage follower (for which it uses a reference voltage Vref), obtaining a voltage at the output Vbat_acond, which is within the dynamic range of the analog-to-digital converter CAD 5.
  • FIG. 7 A scheme is shown in Figure 7 of the circuit of the ammeter 3, which essentially consists of a resistance R32 with a known value of very low tolerance, eg 0.1% (or very high precision) and an operational amplifier 31, to amplify the voltage drop in the resistance R32 ; This voltage drop logically is equal to the value of the resistance R32 by the current Ibat coming from the battery.
  • This voltage signal to the output 3a of the amplifier 31 passes through the analog-digital converter 5 to transform the signal to digital before it enters the microprocessor 7.
  • R32 10 mohm is chosen since the current demanded to the battery passes through it, to avoid large energy losses and excessive thermal dissipation, and therefore has a very small value.
  • the measured voltage will also be, so the amplification given by the amplifier 31 is necessary.
  • the two conditioned voltage and current measurements Vbat_acond, lbat_acond concentrate the information for the measurement of the impedance Z, which is obtained by calculating its ratio (complex), once these voltage and current measurements have been digitized in the analog-digital converter CAD 5 and passed to the frequency domain, V (f), l (f), in microprocessor 7 or DPS, by a direct Fourier transform (FFT).
  • This impedance Z (f) V (f) / l (f) allows the study or diagnosis of the energy storage element (battery), for example, a vehicle.
  • This impedance Z can be represented graphically by means of a Bode or Nyquist diagram, it can serve as a basis for one of the battery diagnostic algorithm.
  • the device of the invention further comprises a data output, such as, through a USB 8, of the microprocessor, for analysis.
  • the device of the invention has been integrated all in a single analog and digital signal processing board that uses two subplates: one with the conditioning of the analog input signal (analog input module , IA) and another one with the conditioning of the analog output (analog output module, OA). These plates are connected to battery 1. This allows:
  • IA / OA modules can be modified adapting to the type of battery to be analyzed.
  • the invention is not limited to the specific embodiments that have been described but also covers, for example, the variants that can be made by the average person skilled in the art (for example, in terms of the choice of materials, dimensions , components, configuration, etc.), within what follows from the claims.

Abstract

The invention relates to a device (100) for measuring the impedance of an energy storage element (1), comprising: means for generating a current stimulus i(f) in the frequency domain with a given spectral content; means for transforming the current stimulus i(f) into a current signal in the time domain; means for adjusting the current signal to a charge level of the energy storage element (1) and for exciting the element with the adjusted current signal; means (3, 4) for measuring voltage and current signals, Vbat, Ibat in the time domain of the energy storage element (1) and for conditioning the measured signals into conditioned voltage and current signals, Vbat_acond, Ibat_acond conditioned to a dynamic range of analog-to-digital conversion means (5); analog-to-digital conversion means (5) for converting the conditioned voltage and current signals Vbat_acond, Ibat_acond, into digitised voltage V(t) and current I(t) signals; and processing and control means (7) configured to analyse the energy of the digitised voltage V(t) and current I(t) signals in the frequency domain in response to the stimulus frequency and to calculate an impedance vector Z(f).

Description

DISPOSITIVO Y PROCEDIMIENTO DE MEDIDA DE IMPEDANCIA DE UN ELEMENTO DE  DEVICE AND PROCEDURE FOR IMPEDANCE MEASUREMENT OF AN ELEMENT OF
ALMACENAMIENTO ENERGÉTICO Campo de la invención  ENERGY STORAGE Field of the invention
La presente invención se engloba en el campo de los dispositivos eléctricos, y más concretamente en la medida de impedancia de tal dispositivo eléctrico mediante espectroscopia. The present invention is encompassed in the field of electrical devices, and more specifically in the measurement of impedance of such electrical device by spectroscopy.
Antecedentes de la invención Background of the invention
Mediante la espectroscopia de impedancia electroquímica (también conocida como EIS, del inglés 'Electrochemical Impedance Spectroscopy') se mide la impedancia de un sistema sobre un rango de frecuencias, y por lo tanto, la respuesta de frecuencia del sistema, la cual nos aporta información sobre las propiedades del sistema de almacenamiento de energía. Los datos obtenidos mediante EIS habitualmente se representan gráficamente en un diagrama de Bode o un diagrama de Nyquist. De esta forma, un sistema de medida de espectroscopia de impedancias permite la medida experimental de la impedancia de un dispositivo bajo prueba -DUT (device under test)- bien pasivo o activo, como es el caso de una batería, en el dominio de la frecuencia. El principio de funcionamiento consiste en excitar ese dispositivo bajo prueba DUT con una corriente con un contenido espectral determinado (típicamente senoidal o de barrido escalón) y medir las variaciones de tensión producidas en bornes del DUT. La relación entre ambas es la impedancia. By means of electrochemical impedance spectroscopy (also known as EIS, from the English 'Electrochemical Impedance Spectroscopy') the impedance of a system over a frequency range is measured, and therefore, the frequency response of the system, which gives us information about the properties of the energy storage system. The data obtained by EIS are usually plotted in a Bode diagram or a Nyquist diagram. In this way, an impedance spectroscopy measurement system allows the experimental measurement of the impedance of a device under test -DUT (device under test) - either passive or active, as is the case of a battery, in the domain of the frequency. The principle of operation is to excite that device under DUT test with a current with a certain spectral content (typically sinusoidal or step sweep) and measure the voltage variations produced in DUT terminals. The relationship between the two is impedance.
El método más extendido en la medida de impedancia es el barrido en frecuencia empleando estímulos de corriente senoidal (método galvanostático). Este consiste en aplicar una perturbación senoidal a distintas frecuencias, estudiando la respuesta del mismo para cada una de ellas. Se obtiene así un valor de impedancia para cada valor de frecuencia, pudiéndose construir un diagrama que represente el espectro de impedancia. Los límites del intervalo de frecuencias, el número de puntos y la elección de un barrido lineal o logarítmico dependen del sistema a estudiar, y se fijan con un determinado criterio para que los resultados proporcionen la máxima información posible. The most widespread method of impedance measurement is frequency scanning using sine current stimuli (galvanostatic method). This consists in applying a sinusoidal disturbance at different frequencies, studying the response of the same for each of them. An impedance value for each frequency value is thus obtained, and a diagram representing the impedance spectrum can be constructed. The limits of the frequency range, the number of points and the choice of a linear or logarithmic sweep depend on the system to be studied, and are set with a certain criterion so that the Results provide the maximum possible information.
En la actualidad existen sistemas comerciales que permiten realizar esta funcionalidad en condiciones de laboratorio, estando dentro del ámbito de los equipos de propósito general, debiendo ser alimentados desde la red eléctrica y precisando de la presencia de un usuario para su puesta en marcha y la obtención de resultados. Currently there are commercial systems that allow this functionality to be carried out in laboratory conditions, being within the scope of general purpose equipment, and must be fed from the power grid and requiring the presence of a user for commissioning and obtaining of results.
En el documento de patente US-2012/0105075-A1 se describe un método para caracterizar un sistema eléctrico mediante espectroscopia de impedancia, en el que se especifica un contenido espectral de la excitación limitando así la medida de impedancia. La principal diferencia con la invención estriba en el hecho de que no se puede cambiar el contenido espectral de un estímulo con amplitud plana en frecuencia. Este nuevo dispositivo permite una entrada multitono (la señal no tiene por qué ser senoides de la misma amplitud) consiguiendo una mejor respuesta. In US-2012/0105075-A1, a method for characterizing an electrical system by impedance spectroscopy is described, in which a spectral content of the excitation is specified thus limiting the impedance measurement. The main difference with the invention lies in the fact that the spectral content of a stimulus with flat amplitude in frequency cannot be changed. This new device allows a multitone input (the signal does not have to be sinewaves of the same amplitude) getting a better response.
En el documento de patente US-2008/0048662-A1 se presenta un sistema para monitorizar el estado de una batería centrándose en la señal de entrada en forma de pulso obteniendo una respuesta discreta en un instante concreto. En estos sistemas conocidos de medida de espectroscopia de impedancias, la señal de entrada o estímulo empleada es una secuencia de señales (normalmente sinusoides) en el dominio de la frecuencia. El problema es que en ciertos dispositivos eléctricos, como por ejemplo, las baterías, la respuesta a la señal de entrada es diferente dependiendo de la frecuencia, siendo ésta más sensible a unas señales en el dominio de la frecuencia que a otras. Si bien se puede estimular con una señal de entrada rica en contenido espectral, la respuesta ante las componentes del estímulo de mayor frecuencia presenta menor sensibilidad (está más atenuada), por lo que se pierde resolución en la medida, necesitando mucha mayor energía para medir con la misma precisión en todo el rango. In the patent document US-2008/0048662-A1 a system is presented to monitor the state of a battery focusing on the pulse-shaped input signal obtaining a discrete response at a specific moment. In these known impedance spectroscopy measurement systems, the input signal or stimulus used is a sequence of signals (usually sinusoids) in the frequency domain. The problem is that in certain electrical devices, such as batteries, the response to the input signal is different depending on the frequency, this being more sensitive to some signals in the frequency domain than others. Although it can be stimulated with an input signal rich in spectral content, the response to the stimulus components of higher frequency has lower sensitivity (is more attenuated), so resolution is lost in the measurement, requiring much greater energy to measure with the same precision throughout the range.
Descripción de la invención Description of the invention
El dispositivo y el procedimiento de medida de la presente invención solucionan el problema de pérdida de resolución planteado con los sistemas existentes que emplean señales de entrada en el dominio de la frecuencia, estimulando el elemento de almacenamiento energético con una señal de entrada en el dominio del tiempo, que inicialmente es conocido en el dominio de la frecuencia; se elimina la parte de continua de la señal medida en el tiempo y únicamente se estudia el comportamiento de la componente alterna de la señal, consiguiendo una mayor resolución en la medida que en el caso de los dispositivos del estado del arte. The device and the measurement procedure of the present invention solve the problem of loss of resolution posed with existing systems employing signals of entry into the frequency domain, stimulating the energy storage element with an input signal in the time domain, which is initially known in the frequency domain; the continuous part of the signal measured in time is eliminated and only the behavior of the alternating component of the signal is studied, achieving a higher resolution as far as in the case of state of the art devices.
Un primer aspecto de la invención se refiere a un dispositivo de medida de impedancia de un elemento de almacenamiento energético, que comprende: A first aspect of the invention relates to an impedance measuring device of an energy storage element, comprising:
- medios de generación de un estímulo de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado; - means for generating a current stimulus i (f) in the frequency domain with a given spectral content;
medios de transformación de dicho estímulo de corriente i(f) en el dominio de la frecuencia a una señal de corriente en el dominio del tiempo;  means of transforming said current stimulus i (f) in the frequency domain to a current signal in the time domain;
medios para ajustar esta señal de corriente en el dominio del tiempo a un nivel de carga del elemento de almacenamiento energético y para excitar el elemento de almacenamiento energético con esta señal de corriente ajustada en el dominio del tiempo; medios para medir unas señales de tensión y corriente, Vbat, Ibat en el dominio del tiempo del elemento de almacenamiento energético y para acondicionar dichas señales medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond a un rango dinámico de unos medios de conversión analógico a digital;  means for adjusting this current signal in the time domain to a charge level of the energy storage element and for exciting the energy storage element with this current signal adjusted in the time domain; means for measuring voltage and current signals, Vbat, Ibat in the time domain of the energy storage element and for conditioning said measured signals to conditioned voltage and current signals, Vbat_acond, lbat_acond to a dynamic range of conversion means analog to digital;
medios de conversión analógico a digital para convertir dichas señales de tensión y de corriente acondicionadas, Vbat_acond, lbat_acond, en una señales de tensión V(t) y corriente l(t) digitalizadas; y,  analog to digital conversion means for converting said conditioned voltage and current signals, Vbat_acond, lbat_acond, into a digitized voltage V (t) and current l (t) signals; Y,
medios de procesamiento y control configurados para:  processing and control means configured to:
- analizar la energía de dichas señales en el dominio de la frecuencia de tensión V(f) y corriente l(f) digitalizadas en torno a la frecuencia de estímulo; y  - analyze the energy of said signals in the domain of the voltage frequency V (f) and current l (f) digitized around the stimulus frequency; Y
- calcular un vector de impedancia Z(f).  - calculate an impedance vector Z (f).
Según una realización preferida, los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprenden un filtro paso-alto para eliminar la componente continua de, al menos, la señal de tensión medida. Estos medios de acondicionamiento preferiblemente además comprenden al menos una etapa amplificadora para amplificar la componente alterna de la señal de tensión no bloqueada por el filtro paso-alto. De esta forma se acondicionan las señales de tensión y corriente medidas en el elemento de almacenamiento energético al rango dinámico de los medios de conversión analógico-digital eliminando primero la componente continua de la señal medida, centrándola (offset) al rango de entrada de dichos medios de conversión y amplificándola para mayor resolución. According to a preferred embodiment, the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a high-pass filter to eliminate the continuous component of at least the measured voltage signal. These conditioning means preferably further comprise at least one amplifier stage for amplifying the alternating component of the voltage signal not blocked by the high-pass filter. This way you they condition the voltage and current signals measured in the energy storage element to the dynamic range of the analog-digital conversion means by first eliminating the continuous component of the measured signal, centering it (offset) to the input range of said conversion means and amplifying it For higher resolution.
La frecuencia de corte de dicho filtro paso-alto depende preferiblemente del espectro de frecuencia del estímulo de corriente i(f), que así mismo depende del rango de frecuencias que se desee observar. En la práctica, el rango de frecuencias empleado que da información útil se encuentra en el intervalo 0,01 Hz-2 kHz. Este intervalo de interés define la frecuencia de corte del filtro paso alto (en este caso, 0,01 Hz). The cut-off frequency of said high-pass filter preferably depends on the frequency spectrum of the current stimulus i (f), which also depends on the frequency range to be observed. In practice, the frequency range used that gives useful information is in the range 0.01 Hz-2 kHz. This range of interest defines the cutoff frequency of the high pass filter (in this case, 0.01 Hz).
Según una realización preferida, los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprenden un filtro paso-alto para eliminar la componente continua de, al menos, la señal de corriente medida. According to a preferred embodiment, the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a high-pass filter to eliminate the continuous component of at least the measured current signal.
De acuerdo con una realización preferida, el dispositivo comprende: According to a preferred embodiment, the device comprises:
un divisor de tensión conectado entre la señal de tensión Vbat medida y el filtro paso- alto;  a voltage divider connected between the measured Vbat voltage signal and the high-pass filter;
- dos resistencias en serie conectadas a una entrada negativa de un primer amplificador, así como una resistencia de realimentación conectada entre salida y entrada negativa del primer amplificador, estando una entrada positiva del primer amplificador puesta a tierra; - two series resistors connected to a negative input of a first amplifier, as well as a feedback resistor connected between output and negative input of the first amplifier, a positive input of the first amplifier being grounded;
dos resistencias en serie conectadas entre la salida del primer amplificador y una entrada negativa de un segundo amplificador, así como una resistencia de realimentación conectada entre salida y entrada negativa del segundo amplificador; y estando conectado a una entrada positiva del segundo amplificador un divisor de tensión formado por dos resistencias y dos condensadores. Según otra realización preferida los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprenden un filtro paso-bajo para obtener un valor de tensión promedio Vprom de la señal de tensión medida Vbat, y un comparador -como por ej., un amplificador- para obtener la señal de tensión acondicionada Vbat_acond como comparación de dichos valor de tensión Vprom y medido Vbat. two resistors in series connected between the output of the first amplifier and a negative input of a second amplifier, as well as a feedback resistor connected between output and negative input of the second amplifier; and a voltage divider formed by two resistors and two capacitors being connected to a positive input of the second amplifier. According to another preferred embodiment, the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a low-pass filter to obtain an average voltage value Vprom of the measured voltage signal Vbat, and a comparator - such as an amplifier - to obtain the conditioned voltage signal Vbat_acond as a comparison of said voltage value Vprom and measured Vbat.
En esta posible realización mediante filtro paso-bajo, preferiblemente: el filtro paso-bajo está formado por una resistencia y varios condensadores conectados en paralelo; el filtro paso-bajo es inicializado mediante dos transistores -como por ej., transistores MOS- y un conjunto de resistencias; dicha señal de tensión Vbat medida se pasa por el filtro paso-bajo para obtener un valor de tensión promedio Vprom; y - dicha tensión promedio Vprom es comparada en el comparador a la señal de tensón Vbat medida, siendo la salida del comparador la señal de tensión acondicionada Vbat_acond. In this possible embodiment by means of a low-pass filter, preferably: the low-pass filter is formed by a resistor and several capacitors connected in parallel; the low-pass filter is initialized by two transistors - such as, for example, MOS transistors - and a set of resistors; said measured Vbat voltage signal is passed through the low-pass filter to obtain an average voltage value Vprom; and - said average voltage Vprom is compared in the comparator to the measured voltage signal Vbat, the comparator output being the conditioned voltage signal Vbat_acond.
Los medios para ajustar esta señal de corriente en el dominio del tiempo a un nivel de carga del elemento de almacenamiento energético y, para excitar el elemento de almacenamiento energético con esta señal de corriente ajustada en el dominio del tiempo preferiblemente comprenden una fuente de corriente. The means for adjusting this current signal in the time domain at a charge level of the energy storage element and, to excite the energy storage element with this current signal adjusted in the time domain preferably comprises a current source.
La fuente de corriente preferiblemente comprende un transistor (puede ser un transistor nMOS) con una resistencia conectada entre drenador del transistor y una tensión de alimentación, y una resistencia conectada entre una fuente del transistor y una puesta a tierra; y además comprende un amplificador conectado a una puerta del transistor en realimentación negativa con la tensión de la fuente. Los medios de generación de un estímulo de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado y los medios de transformación de dicho estímulo de corriente i(f) en el dominio de la frecuencia a una señal de corriente en el dominio del tiempo están preferiblemente integrados en los medios de procesamiento y control, que puede ser un microprocesador o un procesador digital de señal. Preferiblemente el contenido espectral del estímulo de corriente es configurable a diferentes frecuencias de forma que se puede analizar distintas partes del DUT cuyo correcto funcionamiento frente a fallo se observa a frecuencias respectivas. The current source preferably comprises a transistor (it can be an nMOS transistor) with a resistor connected between the drain of the transistor and a supply voltage, and a resistor connected between a source of the transistor and a grounding; and also comprises an amplifier connected to a transistor gate in negative feedback with the source voltage. The means for generating a current stimulus i (f) in the frequency domain with a given spectral content and the means for transforming said current stimulus i (f) in the frequency domain to a current signal in The time domain are preferably integrated in the processing and control means, which can be a microprocessor or a digital signal processor. Preferably the spectral content of the current stimulus is configurable at different frequencies so that different parts of the DUT can be analyzed whose correct operation against failure is observed at respective frequencies.
Es decir, el dispositivo de la invención suministra un estímulo o señal de entrada adecuado en cada momento (mayor amplitud de señal para las frecuencias más bajas), consiguiendo además un ahorro de energía en el suministro de dicho estímulo. Esto se consigue transformando la señal de frecuencia al dominio del tiempo mediante una etapa electrónica de ajuste del estímulo de corriente. That is, the device of the invention provides a suitable input stimulus or signal at all times (greater signal amplitude for the lower frequencies), also achieving energy savings in the supply of said stimulus. This is achieved by transforming the frequency signal to the time domain by means of an electronic step of adjusting the current stimulus.
Finalmente, el dispositivo y procedimiento de medida de impedancia de un elemento de almacenamiento energético de la invención calcula la impedancia de dicho elemento de almacenamiento energético en el dominio de la frecuencia pero aplicando un estímulo transformado del dominio de la frecuencia al dominio del tiempo, y midiendo inicialmente su respuesta eléctrica en términos de tensión y corriente en el dominio del tiempo para finalmente pasarla a un intervalo amplio de frecuencias, consiguiendo así realizar un modelo eléctrico de la batería en el dominio de la frecuencia. Frente a otros dispositivos y procedimientos conocidos, la invención presenta la ventaja añadida de que no daña el elemento de almacenamiento energético gracias al control del estímulo en amplitud y en frecuencia (no generando estímulos en frecuencias que puedan ser perjudiciales para la salud); además el dispositivo es de fácil manejo y los datos que se obtienen pueden analizarse utilizando un modelo de circuitos equivalentes. Finally, the impedance measuring device and method of an energy storage element of the invention calculates the impedance of said energy storage element in the frequency domain but applying a transformed stimulus from the frequency domain to the time domain, and initially measuring its electrical response in terms of voltage and current in the time domain to finally pass it over a wide range of frequencies, thus achieving an electrical model of the battery in the frequency domain. Compared to other known devices and procedures, the invention has the added advantage that it does not damage the energy storage element thanks to the control of the amplitude and frequency stimulus (not generating stimuli at frequencies that may be harmful to health); In addition, the device is easy to use and the data obtained can be analyzed using an equivalent circuit model.
La medida de la impedancia del elemento de almacenamiento energético mediante el dispositivo de la invención permite conocer el estado del mismo pudiendo realizar el correspondiente control o monitorización y detectando posibles fallos, como por ej., oxidaciones en contactos. The measurement of the impedance of the energy storage element by means of the device of the invention allows to know the state of the same, being able to carry out the corresponding control or monitoring and detecting possible failures, such as, for example, oxidations in contacts.
Otro aspecto de la invención se refiere a un procedimiento de medida de impedancia de un elemento de almacenamiento energético, que comprende: Another aspect of the invention relates to an impedance measurement method of an energy storage element, comprising:
generar un estímulo de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado; transformar dicho estímulo de corriente i(f) en el dominio de la frecuencia a una señal de corriente Ibat en el dominio del tiempo; generate a current stimulus i (f) in the frequency domain with a given spectral content; transforming said current stimulus i (f) in the frequency domain to an Ibat current signal in the time domain;
ajustar esta señal de corriente en el dominio del tiempo a un nivel de carga del elemento de almacenamiento energético y excitar el elemento de almacenamiento energético con esta señal de corriente ajustada en el dominio del tiempo;  adjust this current signal in the time domain to a charge level of the energy storage element and excite the energy storage element with this current signal adjusted in the time domain;
medir unas señales de tensión y corriente, Vbat, Ibat en el dominio del tiempo del elemento de almacenamiento energético y acondicionar dichas señales medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond a un rango dinámico de unos medios de conversión analógico a digital;  measure voltage and current signals, Vbat, Ibat in the time domain of the energy storage element and condition said measured signals to conditioned voltage and current signals, Vbat_acond, lbat_acond to a dynamic range of analog to digital conversion means ;
- digitalizar dichas señales de tensión y de corriente acondicionadas, Vbat_acond, lbat_acond, y transformarlas en unas señales de tensión V(t) y corriente l(t) digitalizadas en el dominio de la frecuencia; - digitize said conditioned voltage and current signals, Vbat_acond, lbat_acond, and transform them into voltage signals V (t) and current l (t) digitized in the frequency domain;
analizar la energía de dichas señales en el dominio de la frecuencia de tensión V(f) y corriente l(f) digitalizadas en torno a la frecuencia de estímulo; y  analyze the energy of said signals in the domain of the voltage frequency V (f) and current l (f) digitized around the stimulus frequency; Y
- calcular un vector de impedancia Z(f) como el cociente V(f)/I(f). - calculate an impedance vector Z (f) as the ratio V (f) / I (f).
La etapa de acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond preferiblemente comprende eliminar la componente continua de, al menos, la señal de tensión Vbat medida. The step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond preferably comprises eliminating the continuous component of at least the measured Vbat voltage signal.
Esta componente continua de la señal de tensión Vbat medida puede eliminarse mediante un filtro paso-alto. En este caso preferiblemente se amplifica la componente alterna de la señal de tensión no bloqueada por el filtro paso-alto. La etapa de acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond puede comprender obtener un valor de tensión promedio Vprom de la señal de tensión medida Vbat, y obtener dicha señal de tensión acondicionada Vbat_acond comparando dicho valor de tensión promedio Vprom con la señal de tensión medida Vbat. This continuous component of the measured Vbat voltage signal can be eliminated by a high-pass filter. In this case, the alternating component of the voltage signal not blocked by the high-pass filter is preferably amplified. The step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond may comprise obtaining an average voltage value Vprom of the measured voltage signal Vbat, and obtaining said conditioned voltage signal Vbat_acond by comparing said Average voltage value Vprom with the measured voltage signal Vbat.
El valor de tensión promedio Vprom preferiblemente se obtiene pasando la señal de tensión medida Vbat por un filtro paso-bajo y la comparación se realiza con un amplificador. The average voltage value Vprom is preferably obtained by passing the measured voltage signal Vbat through a low-pass filter and the comparison is made with an amplifier.
En una realización preferida el procedimiento de la invención además comprende una etapa adicional de interpretar los datos obtenidos de Z(f) con patrones y diagnosticar el elemento de almacenamiento energético. In a preferred embodiment the process of the invention further comprises a step additional to interpret the data obtained from Z (f) with patterns and diagnose the energy storage element.
Realizaciones preferidas de este procedimiento se definen en las reivindicaciones dependientes. Preferred embodiments of this procedure are defined in the dependent claims.
Otras ventajas y características adicionales de la invención serán evidentes de la descripción detallada que sigue y serán particularmente señaladas en las reivindicaciones adjuntas. Other advantages and additional features of the invention will be apparent from the detailed description that follows and will be particularly noted in the appended claims.
Breve descripción de las figuras Brief description of the figures
Para complementar la descripción y con objeto de ayudar a una mejor comprensión de las características de la invención, de acuerdo con un ejemplo de realización práctica de la misma, se acompaña como parte integrante de la descripción, un juego de figuras en el que con carácter ilustrativo y no limitativo, se ha representado lo siguiente: To complement the description and in order to help a better understanding of the characteristics of the invention, according to an example of practical implementation thereof, a set of figures in which with character is accompanied as an integral part of the description Illustrative and not limiting, the following has been represented:
La Figura 1 muestra esquemáticamente los diferentes elementos del dispositivo de medida de impedancia de la invención. Figure 1 schematically shows the different elements of the impedance measuring device of the invention.
La Figura 2 muestra un esquema detallado de una primera realización posible del acondicionamiento de la señal de tensión medida en bornes de la batería. La Figura 3 muestra un esquema detallado de una primera realización posible del acondicionamiento de la señal de corriente medida de la batería. Figure 2 shows a detailed diagram of a first possible embodiment of the conditioning of the voltage signal measured at battery terminals. Figure 3 shows a detailed scheme of a first possible embodiment of the conditioning of the measured current signal of the battery.
La Figura 4 muestra un esquema detallado de una segunda realización posible del acondicionamiento de la señal de tensión medida en bornes de la batería. En este caso no es necesario un circuito para acondicionar la señal de corriente medida de la batería, puesto que ya está a baja frecuencia. Figure 4 shows a detailed diagram of a second possible embodiment of the conditioning of the voltage signal measured at battery terminals. In this case, a circuit is not necessary to condition the measured current signal of the battery, since it is already at a low frequency.
La Figura 5 muestra un esquema de la fuente de corriente encargada ajustar el estímulo de corriente generado por el DSP o microprocesador a la carga demandada por la batería en cada momento, y excitar con dicha corriente ajustada la batería. Figure 5 shows a diagram of the current source responsible for adjusting the current stimulus generated by the DSP or microprocessor to the charge demanded by the battery in every moment, and excite with said current adjusted the battery.
La Figura 6 muestra de forma esquemática el acondicionamiento de la señal de tensión medida en los terminales de la batería (que en la Fig. 1 ha sido esquemáticamente representado como un voltímetro 2) y que puede apreciarse con más detalle en las figuras 2 y 4 en sus dos realizaciones preferentes. Figure 6 shows schematically the conditioning of the voltage signal measured at the battery terminals (which in Fig. 1 has been schematically represented as a voltmeter 2) and which can be seen in more detail in Figures 2 and 4 in its two preferred embodiments.
La Figura 7 muestra de forma esquemática la medida de la señal de corriente de la batería (que en la Fig. 1 ha sido esquemáticamente representado como un amperímetro 3), y que puede apreciarse con más detalle en la figura 3. Figure 7 shows schematically the measurement of the battery's current signal (which in Fig. 1 has been schematically represented as an ammeter 3), and which can be seen in more detail in Figure 3.
Descripción de un modo de realización de la invención Description of an embodiment of the invention
En la Figura 1 se muestra un esquema general del dispositivo de medida de impedancia 100 de un dispositivo bajo prueba, en este caso un elemento de almacenamiento eléctrico como es una batería 1 .  A general scheme of the impedance measuring device 100 of a device under test is shown in Figure 1, in this case an electrical storage element such as a battery 1.
Para ello, el dispositivo de medida de impedancia de la invención 100 comprende un microprocesador 7, que también puede ser un procesador digital de señal DSP, que genera un estímulo consistente en una señal de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado. Esta señal de corriente es transformada del dominio de la frecuencia al dominio del tiempo mediante una transformada inversa de Fourier (IFFT) y un convertidor digital-analógico 6. Mediante una fuente de corriente 4 (véase Fig. 5) se ajusta esta señal de corriente resultante en el dominio del tiempo i(t) a la carga necesaria de la batería 1 en cada momento. For this, the impedance measuring device of the invention 100 comprises a microprocessor 7, which can also be a digital DSP signal processor, which generates a stimulus consisting of a current signal i (f) in the frequency domain with a given spectral content. This current signal is transformed from the frequency domain to the time domain by a reverse Fourier transform (IFFT) and a digital-analog converter 6. Using a current source 4 (see Fig. 5) this current signal is set resulting in the time domain i (t) at the necessary charge of the battery 1 at each moment.
Como parte del dispositivo 100 de la invención, éste incluye sendos circuitos de medida y acondicionamiento de las señales de tensión e intensidad instantáneas medidas de la batería 1 . Estos circuitos han sido representados esquemáticamente en la Figura 1 como un voltímetro 2 y un amperímetro 3 conectados en bornes de y en serie con la batería 1 , respectivamente. En estos circuitos, además de realizarse las medidas de tensión y corriente instantáneas de la batería, se acondicionan las señales al rango dinámico de un convertidor analógico-digital ADC 5, donde las señales son digitalizadas antes de entrar en el microprocesador 7, donde se transforman la señales de tensión y corriente al dominio de la frecuencia mediante por ej., transformación directa de Fourier (FFT), para determinar la impedancia de la batería en el rango de frecuencias correspondiente. As part of the device 100 of the invention, this includes two measuring and conditioning circuits of the instantaneous measured voltage and current signals of the battery 1. These circuits have been schematically represented in Figure 1 as a voltmeter 2 and an ammeter 3 connected in terminals of and in series with the battery 1, respectively. In these circuits, in addition to the instantaneous battery voltage and current measurements, the signals are conditioned to the dynamic range of an ADC 5 analog-digital converter, where the signals are digitized before entering the microprocessor 7, where they are transformed the voltage and current signals to the domain of the frequency by eg, direct Fourier transformation (FFT), to determine the impedance of the battery in the corresponding frequency range.
El circuito de medida y acondicionamiento de la señal de tensión o voltímetro 2 no mide tensiones escaladas como ocurre en los dispositivos del estado de la técnica (la tensión medida es en el punto intermedio entre dos resistencias), sino que mide una tensión filtrada o banda de interés de tensión. Esto es porque sólo interesa la parte alterna (desechando la componente de continua) de la señal de tensión de la batería 1 . Para filtrar la señal de tensión existen dos posibles realizaciones preferidas del circuito de medida y acondicionamiento de la señal de tensión o voltímetro 2. The measurement and conditioning circuit of the voltage signal or voltmeter 2 does not measure scaled voltages as in the state of the art devices (the measured voltage is at the intermediate point between two resistors), but measures a filtered voltage or band of tension interest. This is because only the alternating part (discarding the continuous component) of the battery voltage signal 1 is of interest. For filtering the voltage signal there are two possible preferred embodiments of the measurement and conditioning circuit of the voltage signal or voltmeter 2.
En la Figura 2 se muestra una primera realización preferida posible del acondicionamiento de la señal de tensión Vbat medida en terminales 1 a-1 b de la batería 1 . La señal de tensión Vbat es una señal de alta tensión que es acondicionada eliminando su componente de continua para la gama de frecuencias a analizar (en el ejemplo mostrado para frecuencias superiores a 10 mHz); para ello se hace pasar la señal de tensión por un filtro paso-alto formado por un condensador C23 y una resistencia R24 conectada a tierra, para así fijar su componente alterna a partir de 10 mHz antes de pasar por un primer amplificador 21 a. Previo al filtro paso-alto formado por el condensador C23 y la resistencia R24 se incluye un divisor de tensión de Vbat formado por las resistencias R1 , R2 y R3; la ganancia del primer amplificador 21 a se controla por medio de un potenciómetro R4 conectado en serie con una resistencia R5 que se conectan a la entrada negativa del primer amplificador 21 a, así como mediante una resistencia R6 de realimentación conectada entre la salida del primer amplificador 21 a y su entrada negativa. Por su parte el primer amplificador 21 a está alimentado mediante tensiones de +12 V y -12 V, con respectivos condensadores C10 y C1 1 puestos a tierra para evitar ruidos. A first possible preferred embodiment of the conditioning of the voltage signal Vbat measured at terminals 1 a-1 b of the battery 1 is shown in Figure 2. The Vbat voltage signal is a high voltage signal that is conditioned by eliminating its continuous component for the frequency range to be analyzed (in the example shown for frequencies greater than 10 mHz); for this, the voltage signal is passed through a high-pass filter formed by a capacitor C23 and a resistor R24 connected to ground, in order to fix its alternating component from 10 mHz before passing through a first amplifier 21 a. Prior to the high-pass filter formed by the capacitor C23 and the resistor R24 a voltage divider of Vbat is included formed by the resistors R1, R2 and R3; the gain of the first amplifier 21 a is controlled by means of a potentiometer R4 connected in series with a resistor R5 that is connected to the negative input of the first amplifier 21 a, as well as by a feedback resistor R6 connected between the output of the first amplifier 21 a and its negative entry. For its part, the first amplifier 21 a is powered by voltages of +12 V and -12 V, with respective capacitors C10 and C1 1 grounded to avoid noise.
Mediante un segundo amplificador 21 b se realiza la amplificación de la señal de alterna que no ha sido bloqueada, controlándose la ganancia de este segundo amplificador mediante otro potenciómetro R7 conectado en serie con una resistencia R8, que se conectan a la entrada negativa del segundo amplificador 21 b, junto con una resistencia R9 de realimentación. De forma similar al primer amplificador 21 a, el segundo amplificador 21 b está alimentado mediante tensiones de +12 V y -12 V, con respectivos condensadores C5 y C4 puestos a tierra y que sirven para evitar ruido. By means of a second amplifier 21 b, the amplification of the alternating signal that has not been blocked is performed, the gain of this second amplifier being controlled by another potentiometer R7 connected in series with a resistor R8, which is connected to the negative input of the second amplifier 21 b, together with a feedback resistance R9. Similar to the first amplifier 21 a, the second amplifier 21 b is powered by voltages of +12 V and -12 V, with respective capacitors C5 and C4 grounded and used to avoid noise.
Mediante el divisor de tensión formado por las resistencias R25 conectadas entre los condensadores C7 y C2 -que sirven para evitar ruido- se consigue tener una tensión constante en la entrada positiva del segundo amplificador 21 b que es comparada con la tensión Vbat medida en bornes de la batería 1 tras la primera etapa de amplificación. De esta forma se centra la señal de salida, que es la señal de tensión de la batería ya acondicionada Vbat_acond, en el rango de entrada del convertidor analógico-digital DAC 5 (2,5 V), maximizándose el rango dinámico de la señal amplificada y aumentando la relación señal ruido (SNR, signal to noise ratio) en esta señal de tensión de la batería ya acondicionada Vbat_acond. By means of the voltage divider formed by the resistors R25 connected between the capacitors C7 and C2 - which serve to avoid noise - it is possible to have a constant voltage at the positive input of the second amplifier 21 b which is compared with the Vbat voltage measured in terminals of Battery 1 after the first stage of amplification. In this way the output signal, which is the voltage signal of the Vbat_acond battery already conditioned, is centered in the input range of the DAC 5 analog-digital converter (2.5 V), maximizing the dynamic range of the amplified signal and increasing the signal to noise ratio (SNR) in this voltage signal of the already conditioned Vbat_acond battery.
Los valores de las resistencias son: R1 =R2=1 kohm; R3=100 ko m; R24=1 ,6 ko m; R25=10 kohm. Y los valores de los condensadores son: C23=10 mF; C10=C1 1 =C2=C4=C5=C7=100 nF. The resistance values are: R1 = R2 = 1 kohm; R3 = 100 ko m; R24 = 1, 6 or m; R25 = 10 kohm. And the capacitor values are: C23 = 10 mF; C10 = C1 1 = C2 = C4 = C5 = C7 = 100 nF.
Como se ha indicado, este circuito de acondicionamiento de la señal de tensión tiene alta ganancia, puesto que los requerimientos de corriente son pequeños en relación con la capacidad que tienen las baterías de facilitar intensidad-potencia lo que se traduce en una pequeña respuesta en forma de caída de tensión. Por ello se incluyen dos amplificaciones 21 a y 21 b para conseguir este objetivo, y modificando los valores de las resistencias R4-R5- R6 y R7-R8-R9 se controla el valor de la ganancia de cada amplificador. As indicated, this voltage signal conditioning circuit has a high gain, since the current requirements are small in relation to the capacity of the batteries to facilitate intensity-power which translates into a small response in form of voltage drop. Therefore, two amplifications 21 a and 21 b are included to achieve this objective, and by modifying the values of the resistors R4-R5-R6 and R7-R8-R9, the gain value of each amplifier is controlled.
En la Figura 3 se muestra un circuito de medida y acondicionamiento de la señal de corriente Ibat medida en la batería 1 (muy similar al circuito de medida y acondicionamiento de la señal de tensión Vbat medida en la batería 1 ). Aunque la señal de corriente Ibat sea una señal cuasi-conocida ya que no es más que la adaptación del estímulo de corriente, hay que medirla porque siempre puede haber distorsiones al generar la señal. Como hay que introducir un filtro para la medida y acondicionamiento de la parte de tensión que va a introducir una distorsión definida, este mismo filtro se aplica para acondicionar la parte de corriente (la medida que se obtiene de impedancia es V/l, si a V se le aplican distorsiones, estas mismas se le aplican a I). A measurement and conditioning circuit of the Ibat current signal measured in battery 1 is shown in Figure 3 (very similar to the measurement and conditioning circuit of the Vbat voltage signal measured in battery 1). Although the Ibat current signal is a quasi-known signal since it is nothing more than the adaptation of the current stimulus, it must be measured because there can always be distortions when generating the signal. Since a filter must be introduced for the measurement and conditioning of the voltage part that is going to introduce a defined distortion, this same filter is applied to condition the current part (the measurement that is obtained from impedance is V / l, if V distortions are applied, they apply to I).
En esta Figura 3 las resistencias R24', R25', R1 '-R9', los condensadores C23' C2', C4\ C5', C7', C10' y C1 1 ' y los amplificadores 21 a', 21 b' realizan las mismas funciones que, respectivamente, las resistencias R24, R24, R1 -R9, los condensadores R23, C2, C4, C5, C7, C10 y C1 1 y los amplificadores 21 a, 21 b de la Figura 2. Los valores de las resistencias y de los condensadores son: R1 '=R2'=100 ohm; R3'=100 kohm; R24'=1 ,6 kohm; R25'=10 kohm; C23'=10 mF; C10'=C1 1 '=C2'=C4,=C5'=C7,=100 nF. In this Figure 3 the resistors R24 ', R25', R1 '-R9', the capacitors C23 'C2', C4 \ C5 ', C7 ', C10' and C1 1 'and amplifiers 21 a', 21 b 'perform the same functions as, respectively, resistors R24, R24, R1-R9, capacitors R23, C2, C4, C5, C7, C10 and C1 1 and amplifiers 21 a, 21 b of Figure 2. The values of the resistors and capacitors are: R1 '= R2' = 100 ohm; R3 '= 100 kohm; R24 '= 1, 6 kohm; R25 '= 10 kohm; C23 '= 10 mF; C10 '= C1 1' = C2 '= C4 , = C5' = C7 , = 100 nF.
Esta etapa de acondicionamiento de corriente en paralelo al acondicionamiento de tensión hace que las medidas de ambas señales sean más similares entre sí en relación a posibles interferencias de ruido y no-linealidades del dispositivo y del propio acondicionamiento. En este acondicionamiento de corriente se introduce también un filtro paso-alto, para que ambas ramas estén afectadas por el mismo tipo de filtro en frecuencia. Si bien hay que indicar que el circuito de acondicionamiento de la señal de tensión tiene una ganancia más alta que la ganancia del circuito de acondicionamiento de la señal de corriente. This stage of current conditioning in parallel to the voltage conditioning makes the measurements of both signals more similar to each other in relation to possible noise interference and non-linearities of the device and the conditioning itself. In this current conditioning a high-pass filter is also introduced, so that both branches are affected by the same type of frequency filter. While it should be noted that the voltage signal conditioning circuit has a higher gain than the current signal conditioning circuit gain.
En la Figura 4 se muestra una segunda realización preferente posible del acondicionamiento de la señal de tensión Vbat medida en terminales 1 a-1 b de la batería 1 . En este caso concreto el circuito tiene un filtro paso-bajo 50 deja pasar únicamente la señal con frecuencia inferior a 10 mHz. Los dos transistores MOS 53 y las resistencias R mostradas en esta Figura 4 sirven para hacer una precarga de cinco condensadores C52 conectados en paralelo que componen el filtro paso-bajo 50 (para inicializar el filtro), donde la resistencia 51 es la resistencia de entrada del filtro. De esta forma, aunque la batería 1 tiene oscilaciones en función de la corriente, tras pasar la tensión instantánea de la batería Vbat por el filtro paso-bajo 50 se obtiene el valor de tensión promedio Vprom, cuyo valor puede comprobarse a través de una sonda 60 coaxial. La puerta del transistor MOS 53 está conectada a una pata de salida digital del microprocesador 7. Mediante esta pata se controla el estado de activación del MOS. A second possible preferred embodiment of the conditioning of the voltage signal Vbat measured in terminals 1 a-1 b of the battery 1 is shown in Figure 4. In this specific case, the circuit has a low-pass filter 50, which only lets the signal with a frequency below 10 mHz. The two MOS transistors 53 and the resistors R shown in this Figure 4 serve to preload five capacitors C52 connected in parallel that make up the low-pass filter 50 (to initialize the filter), where the resistor 51 is the input resistance of the filter. In this way, although the battery 1 has oscillations depending on the current, after passing the instantaneous voltage of the battery Vbat through the low-pass filter 50, the average voltage value Vprom is obtained, the value of which can be checked through a probe 60 coaxial The door of the MOS transistor 53 is connected to a digital output leg of the microprocessor 7. This leg controls the activation status of the MOS.
Este filtro paso-bajo 50 se ajusta al rango de frecuencias que se quiera medir. Este valor de tensión promedio Vprom depende de la batería 1 , entre otros, de su nivel de carga. En el caso de baterías de vehículos eléctricos, son típicas tensiones de batería de 400V. Por tanto, en ambos nodos (Vbat y Vprom) los valores de tensión hacen necesario elegir de forma cuidadosa, tanto el amplificador 21 , como el transistor 53. De esta forma en el amplificador 21 se introduce el valor instantáneo de la tensión Vbat en bornes de la batería 1 que es comparado con el valor de tensión promedio Vprom, obteniéndose así la variación en el tiempo de la tensión en la batería 1 a la salida del amplificador 21 , que es la señal de tensión de la batería ya acondicionada Vbat_acond para ser introducida en el convertidor analógico-digital CAD 5. This low-pass filter 50 adjusts to the frequency range to be measured. This average voltage value Vprom depends on battery 1, among others, on its charge level. In the case of electric vehicle batteries, 400V battery voltages are typical. Therefore, in both nodes (Vbat and Vprom) the voltage values make it necessary to carefully choose both the amplifier 21 and the transistor 53. In this way, the instantaneous value of the voltage Vbat is inserted into the terminals of the battery 1 in the amplifier 21 which is compared with the average voltage value Vprom, thus obtaining the variation in the time of the voltage in the battery 1 at the output of the amplifier 21, which is the voltage signal of the battery already conditioned Vbat_acond to be introduced in the analog-digital converter CAD 5.
Para obtener la tensión promedio se elige el valor de R51 =10 ko m y C52= 2mF (en este caso se han utilizado cinco en paralelo, haciendo un total de 10 mF). Por su parte, R10 tiene la función de ajuste de la ganancia del amplificador 21 . Se elige un valor de R10=100 kohm para obtener una ganancia de 10. To obtain the average voltage, the value of R51 = 10 ko m and C52 = 2mF is chosen (in this case five have been used in parallel, making a total of 10 mF). For its part, R10 has the function of adjusting the gain of the amplifier 21. A value of R10 = 100 kohm is chosen to obtain a gain of 10.
Es decir, mediante una u otra realización se elimina la parte de continua de la señal de tensión medida en los terminales 1 a-1 b de la batería 1 para tener una medida de tensión dentro de un rango determinado. Este rango viene dado por el rango dinámico del convertidor analógico-digital DAC 5. La señal de la corriente continua ocupa más bits que la de la señal alterna. Al quitar la parte continua de la señal de tensión se aprovecha todo el rango del convertidor analógico-digital CAD 5 consiguiendo una medida de mejor resolución. That is, by one or another embodiment, the continuous part of the voltage signal measured at terminals 1 a-1 b of the battery 1 is eliminated to have a voltage measurement within a given range. This range is given by the dynamic range of the analog-to-digital converter DAC 5. The direct current signal occupies more bits than that of the alternating signal. When removing the continuous part of the voltage signal, the entire range of the analog-to-digital converter CAD 5 is used, achieving a better resolution measurement.
De esta forma se consigue una señal filtrada en el rango de interés, que varía con el tiempo, y con una alta resolución de la medida de tensión, lo que permite obtener una buena medida de impedancia. In this way a filtered signal is obtained in the range of interest, which varies over time, and with a high resolution of the voltage measurement, which allows a good impedance measurement to be obtained.
En la Figura 5 se muestra la fuente de corriente 4 que proporciona el estímulo de corriente o excitación a la batería 1 . Se trata de una fuente de corriente 4 controlada por tensión, de manera que si se incrementa la tensión se incrementa la corriente y si se reduce la tensión en sus bornes de la misma forma se reduce la corriente. De esta forma la fuente de corriente 4 ajusta la señal generada por el microprocesador 7 o DSP para demandar un estímulo de corriente determinado a la batería. Esta etapa de ajuste de la señal generada por el microprocesador 7 en el estímulo de corriente demandado a la batería 1 incluye un transistor nMOS 44 que modula este estímulo de corriente y que se controla mediante la tensión de su fuente Vs (punto 44s). El transistor nMOS 44 se abre o se cierra según la tensión. Entre fuente 44s y puerta 44g la resistencia Rs es conocida, por lo que aplicando la Ley de Ohm se puede conocer el estímulo de corriente lbat,eis que se le demanda a la batería: lbat,eis=ls=Vs/Rs; este estímulo de corriente lbat,eis que se demanda a la batería 1 debería ser prácticamente igual a la señal de corriente medida Ibat por el amperímetro 3, salvo por distorsiones entre la generación y la medida. Figure 5 shows the current source 4 that provides the current or excitation stimulus to the battery 1. It is a voltage controlled current source 4, so that if the voltage is increased the current is increased and if the voltage at its terminals is reduced in the same way the current is reduced. In this way the current source 4 adjusts the signal generated by the microprocessor 7 or DSP to demand a given current stimulus from the battery. This step of adjusting the signal generated by the microprocessor 7 in the current stimulus demanded from the battery 1 includes a transistor nMOS 44 that modulates this current stimulus and is controlled by the voltage of its source Vs (point 44s). Transistor nMOS 44 opens or closes depending on the voltage. Between source 44s and gate 44g the resistance Rs is known, so by applying Ohm's Law the stimulus of lbat current, the battery is being demanded: lbat, eis = ls = Vs / Rs; this stimulus of current lbat, which is demanded from battery 1 should be practically equal to the measured current signal Ibat by the ammeter 3, except for distortions between generation and measurement.
Como control del transistor 44 se tiene un amplificador operacional 41 en modo fuente de corriente 4 controlada por tensión, ya que su lazo de realimentación es la caída de tensión entre puerta 44g-fuente 44s. De esta forma se persigue que la tensión de la fuente Vs siga al estímulo de corriente bajo condiciones de realimentación negativa y que el amplificador operacional 41 funcione en su zona lineal; es decir, que la tensión Vs siga a la tensión en la entrada positiva del amplificador operacional 41 . As a control of transistor 44 there is an operational amplifier 41 in voltage-controlled current source mode 4, since its feedback loop is the voltage drop between gate 44g-source 44s. In this way it is pursued that the voltage of the source Vs follows the current stimulus under negative feedback conditions and that the operational amplifier 41 operates in its linear zone; that is, that the voltage Vs follows the voltage at the positive input of the operational amplifier 41.
Por otra parte, para evitar que el transistor nMOS 44 tenga que disipar toda la potencia (que sería VbatHbat,eis) demandada para el estímulo de corriente, se inserta una resistencia R42 de 10 ohm en el drenador (punto 44d) del transistor 44. La resistencia R43 de 1 ohm conectada entre la fuente del transistor y tierra permite sensar el valor de corriente, ajusfando la salida del amplificador 41 al valor necesario para que la corriente siga a la consigna (salida del CDA 6). En la Figura 6 se muestra de forma esquemática el acondicionamiento de la señal de tensión medida en la batería de la primera realización mostrada en la Figura 2. La señal de tensión medida Vbat se pasa por un filtro paso-alto formado por un condensador C23 de 10 mF y una resistencia R24 de 1 ,6 kohm conectada a tierra; este filtro paso-alto deja pasar la alta frecuencia: rechaza la corriente continua y deja pasar la señal a partir de una frecuencia, en este ejemplo concreto a partir de 10 mHz. El amplificador 21 actúa como seguidor de tensión (para lo cual utiliza una tensión de referencia Vref), obteniéndose una tensión a la salida Vbat_acond, que está dentro del rango dinámico del convertidor analógico-digital CAD 5. En la Figura 7 se muestra un esquema del circuito del amperímetro 3, que esencialmente está formado por una resistencia R32 con valor conocido de muy baja tolerancia, por ej., 0.1 % (o muy alta precisión) y un amplificador 31 operacional, para amplificar la caída de tensión en la resistencia R32; esta caída de tensión lógicamente es igual al valor de la resistencia R32 por la corriente Ibat procedente de la batería. Esta señal de tensión a la salida 3a del amplificador 31 pasa por el convertidor analógico-digital 5 para transformar la señal a digital antes de su entrada al microprocesador 7. Como se puede ver en la Figura 1 este amperímetro 3 está conectado físicamente al terminal 1 b de la batería; el otro terminal 1 a de la batería 1 está conectado a la fuente de corriente 4 que está dispuesta en serie con el amperímetro de forma que la corriente que sale de la batería 1 pasa por la resistencia R32=10 mohm interna del amperímetro para una adecuada medida de la impedancia. Se escoge R32=10 mohm puesto que por ella pasa la corriente demandada a la batería, para evitar grandes pérdidas de energía y excesiva disipación térmica, y por ello tiene un valor muy reducido. La tensión medida también lo será, por lo que es necesaria la amplificación dada por el amplificador 31 . On the other hand, to avoid that the nMOS transistor 44 has to dissipate all the power (which would be VbatHbat, eis) demanded for the current stimulus, a resistance R42 of 10 ohm is inserted into the drain (point 44d) of the transistor 44. The resistor R43 of 1 ohm connected between the source of the transistor and earth allows the current value to be sensed, adjusting the output of the amplifier 41 to the value necessary for the current to follow the setpoint (output of CDA 6). In Figure 6 the conditioning of the voltage signal measured in the battery of the first embodiment shown in Figure 2 is shown schematically. The measured voltage signal Vbat is passed through a high-pass filter formed by a capacitor C23 of 10 mF and an R24 resistor of 1.6 kohm grounded; This high-pass filter lets the high frequency pass: it rejects the direct current and lets the signal pass from a frequency, in this particular example from 10 mHz. The amplifier 21 acts as a voltage follower (for which it uses a reference voltage Vref), obtaining a voltage at the output Vbat_acond, which is within the dynamic range of the analog-to-digital converter CAD 5. A scheme is shown in Figure 7 of the circuit of the ammeter 3, which essentially consists of a resistance R32 with a known value of very low tolerance, eg 0.1% (or very high precision) and an operational amplifier 31, to amplify the voltage drop in the resistance R32 ; This voltage drop logically is equal to the value of the resistance R32 by the current Ibat coming from the battery. This voltage signal to the output 3a of the amplifier 31 passes through the analog-digital converter 5 to transform the signal to digital before it enters the microprocessor 7. As can be seen in Figure 1 this ammeter 3 is physically connected to the terminal 1 b of the battery; the other terminal 1 a of the battery 1 is connected to the current source 4 which is arranged in series with the ammeter so that the current exiting the battery 1 passes through the resistance R32 = 10 mohm internal of the ammeter for proper impedance measurement. R32 = 10 mohm is chosen since the current demanded to the battery passes through it, to avoid large energy losses and excessive thermal dissipation, and therefore has a very small value. The measured voltage will also be, so the amplification given by the amplifier 31 is necessary.
En el dispositivo de la invención se contempla demandar una corriente de aproximadamente 0,1 A para una batería de 8Ah y transitorios de 80 mA de amplitud. Si se aumenta esta corriente se recalcularían las resistencias del drenador del transistor nMOS 44 (Fig. 5). In the device of the invention it is contemplated to demand a current of approximately 0.1 A for an 8Ah battery and transients of 80 mA amplitude. If this current is increased, the resistors of the nMOS 44 transistor drain would be recalculated (Fig. 5).
Las dos medidas acondicionadas de tensión y corriente Vbat_acond, lbat_acond concentran la información para la medida de la impedancia Z, que se obtiene calculando su cociente (complejo), una vez estas medidas de tensión y corriente han sido digitalizadas en el convertidor analógico-digital CAD 5 y pasadas al dominio de la frecuencia, V(f), l(f), en el microprocesador 7 o DPS, mediante una transformada directa de Fourier (FFT). Esta impedancia Z(f)=V(f)/l(f) permite el estudio o diagnosis del elemento de almacenamiento de energía (batería), de por ej., un vehículo. Esta impedancia Z puede ser representada gráficamente mediante un diagrama de Bode o de Nyquist, puede servir de base a un del algoritmo de diagnosis de la batería. The two conditioned voltage and current measurements Vbat_acond, lbat_acond concentrate the information for the measurement of the impedance Z, which is obtained by calculating its ratio (complex), once these voltage and current measurements have been digitized in the analog-digital converter CAD 5 and passed to the frequency domain, V (f), l (f), in microprocessor 7 or DPS, by a direct Fourier transform (FFT). This impedance Z (f) = V (f) / l (f) allows the study or diagnosis of the energy storage element (battery), for example, a vehicle. This impedance Z can be represented graphically by means of a Bode or Nyquist diagram, it can serve as a basis for one of the battery diagnostic algorithm.
El dispositivo de la invención además comprende una salida de datos, como por ej., a través de un USB 8, del microprocesador, para su análisis. The device of the invention further comprises a data output, such as, through a USB 8, of the microprocessor, for analysis.
Desde un punto de vista de electrónica, el dispositivo de la invención ha sido integrado todo en una única placa de procesamiento de la señal analógica y digital que se sirve de dos subplacas: una con el acondicionamiento de la señal de entrada analógica (módulo entrada analógica, IA) y otra con el acondicionamiento de la salida analógica (módulo salida analógica, OA). Estas placas se conectan a la batería 1 . Esto permite: From an electronics point of view, the device of the invention has been integrated all in a single analog and digital signal processing board that uses two subplates: one with the conditioning of the analog input signal (analog input module , IA) and another one with the conditioning of the analog output (analog output module, OA). These plates are connected to battery 1. This allows:
Flexibilidad de diseño y adaptación a las variaciones de las baterías, ya que los módulos IA/OA se pueden modificar adaptándose al tipo de batería que se desee analizar.Design flexibility and adaptation to battery variations, since IA / OA modules can be modified adapting to the type of battery to be analyzed.
Mayor seguridad de operación al rechazar los niveles de tensión de la batería por encima del nivel de entrada del convertidor analógico-digital, entregando únicamente los valores transitorios de tensión adaptados al rango de entrada de los circuitos de conversión analógico-digital, evitando la posibilidad de fallos. Increased operational safety by rejecting battery voltage levels above the input level of the analog-digital converter, delivering only the voltage transient values adapted to the input range of the analog-digital conversion circuits, avoiding the possibility of failures.
Mayor facilidad y menor coste de reemplazo en caso de avería, al ser las partes más susceptibles de fallo incluidas en subplacas que son fácilmente remplazables.  Greater ease and lower cost of replacement in case of failure, being the most susceptible parts of failure included in subplates that are easily replaceable.
Autonomía del equipo que le permite estar integrado en el DUT sin necesidad de fuente de alimentación (se puede alimentar directamente del DUT)  Autonomy of the equipment that allows it to be integrated into the DUT without the need for a power supply (can be fed directly from the DUT)
Por otra parte, la invención no está limitada a las realizaciones concretas que se han descrito sino abarca también, por ejemplo, las variantes que pueden ser realizadas por el experto medio en la materia (por ejemplo, en cuanto a la elección de materiales, dimensiones, componentes, configuración, etc.), dentro de lo que se desprende de las reivindicaciones. On the other hand, the invention is not limited to the specific embodiments that have been described but also covers, for example, the variants that can be made by the average person skilled in the art (for example, in terms of the choice of materials, dimensions , components, configuration, etc.), within what follows from the claims.

Claims

REIVINDICACIONES
1 . Dispositivo de medida de impedancia (100) de un elemento de almacenamiento energético (1 ), caracterizado por que comprende: medios de generación de un estímulo de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado; one . Impedance measuring device (100) of an energy storage element (1), characterized in that it comprises: means for generating a current stimulus i (f) in the frequency domain with a given spectral content;
medios de transformación de dicho estímulo de corriente i(f) en el dominio de la frecuencia a una señal de corriente en el dominio del tiempo;  means of transforming said current stimulus i (f) in the frequency domain to a current signal in the time domain;
medios para ajustar esta señal de corriente en el dominio del tiempo a un nivel de carga del elemento de almacenamiento energético (1 ) y para excitar el elemento de almacenamiento energético (1 ) con esta señal de corriente ajustada en el dominio del tiempo;  means for adjusting this current signal in the time domain to a charge level of the energy storage element (1) and to excite the energy storage element (1) with this current signal adjusted in the time domain;
medios para medir (3, 4) unas señales de tensión y corriente, Vbat, Ibat en el dominio del tiempo del elemento de almacenamiento energético (1 ) y para acondicionar dichas señales medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond a un rango dinámico de unos medios de conversión analógico a digital (5);  means for measuring (3, 4) voltage and current signals, Vbat, Ibat in the time domain of the energy storage element (1) and for conditioning said measured signals to conditioned voltage and current signals, Vbat_acond, lbat_acond a a dynamic range of analog to digital conversion means (5);
medios de conversión analógico a digital (5) para convertir dichas señales de tensión y de corriente acondicionadas, Vbat_acond, lbat_acond, en una señales de tensión V(t) y corriente l(t) digitalizadas; y,  analog to digital conversion means (5) for converting said conditioned voltage and current signals, Vbat_acond, lbat_acond, into a digitized voltage V (t) and current l (t) signals; Y,
medios de procesamiento y control (7) configurados para:  processing and control means (7) configured to:
- analizar la energía de dichas señales en el dominio de la frecuencia de tensión V(f) y corriente l(f) digitalizadas en torno a la frecuencia de estímulo; y  - analyze the energy of said signals in the domain of the voltage frequency V (f) and current l (f) digitized around the stimulus frequency; Y
- calcular un vector de impedancia Z(f).  - calculate an impedance vector Z (f).
2. Dispositivo según la reivindicación 1 , en el que los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprenden un filtro paso-alto (C23, R24) aplicable a la señal de tensión Vbat medida. 2. Device according to claim 1, wherein the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a high-pass filter (C23, R24) applicable to the signal of Vbat voltage measured.
3. Dispositivo según la reivindicación 2, en el que los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond además comprenden al menos una etapa amplificadora (21 a, 21 b) para amplificar la componente alterna de la señal de tensión no bloqueada por el filtro paso-alto (C23, R24). 3. Device according to claim 2, wherein the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond further comprise at least one amplifier stage (21 a, 21 b) for amplifying the alternating component of the voltage signal does not blocked by the high-pass filter (C23, R24).
4. Dispositivo según cualquier de las reivindicaciones 2-3, en el que los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprenden un filtro paso-alto (C23', R24') aplicable a la señal de corriente Ibat medida. 4. Device according to any of claims 2-3, wherein the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a high-pass filter (C23 ', R24' ) applicable to the measured Ibat current signal.
5. Dispositivo según cualquiera de las reivindicaciones 2-4, en el que la frecuencia de corte de dichos filtros paso-alto (C23, R24; C23', R24') dependen del espectro de frecuencia del estímulo de corriente i(f). 5. Device according to any of claims 2-4, wherein the cut-off frequency of said high-pass filters (C23, R24; C23 ', R24') depends on the frequency spectrum of the current stimulus i (f).
6. Dispositivo según cualquiera la reivindicación 5, en el que dicha frecuencia de corte está entre 10 mHz y 2 kHz. 6. Device according to any one of claim 5, wherein said cut-off frequency is between 10 mHz and 2 kHz.
7. Dispositivo según cualquiera de las reivindicaciones 2-6, que comprende: 7. Device according to any of claims 2-6, comprising:
un divisor de tensión (R1 , R2, R3; R1 ', R2', R3') conectado entre la señal de tensión Vbat medida y el filtro paso-alto (C23, R24; C23', R24');  a voltage divider (R1, R2, R3; R1 ', R2', R3 ') connected between the measured Vbat voltage signal and the high-pass filter (C23, R24; C23', R24 ');
dos resistencias en serie (R4, R5; R4', R5') conectadas a una entrada negativa de un primer amplificador (21 a; 21 a'), así como una resistencia (R6; R6') de realimentación conectada entre salida y entrada negativa del primer amplificador (21 a; 21 a'), estando una entrada positiva del primer amplificador (21 a; 21 a') puesta a tierra;  two series resistors (R4, R5; R4 ', R5') connected to a negative input of a first amplifier (21 a; 21 a '), as well as a feedback resistor (R6; R6') connected between output and input negative of the first amplifier (21 a; 21 a '), a positive input of the first amplifier (21 a; 21 a') being grounded;
dos resistencias en serie (R7, R8; R7', R8') conectadas entre la salida del primer amplificador (21 a; 21 a') y una entrada negativa de un segundo amplificador (21 b; 21 b'), así como una resistencia (R9; R9') de realimentación conectada entre salida y entrada negativa del segundo amplificador (21 b; 21 b'); y estando conectado a una entrada positiva del segundo amplificador (21 b; 21 b') un divisor de tensión formado por dos resistencias (R25, R25') y dos condensadores (C2, C7; C2', C7').  two series resistors (R7, R8; R7 ', R8') connected between the output of the first amplifier (21 a; 21 a ') and a negative input of a second amplifier (21 b; 21 b'), as well as a feedback resistor (R9; R9 ') connected between output and negative input of the second amplifier (21 b; 21 b'); and being connected to a positive input of the second amplifier (21 b; 21 b ') a voltage divider formed by two resistors (R25, R25') and two capacitors (C2, C7; C2 ', C7').
8. Dispositivo según la reivindicación 7, en el que los valores de las resistencias son R1 =R2=1 kohm, R3=100 kohm, R24=1 ,6 kohm, R25=10 kohm y los valores de los condensadores son C23=10 mF, C10=C1 1 =C2=C4=C5=C7=100 nF. 8. Device according to claim 7, wherein the values of the resistors are R1 = R2 = 1 kohm, R3 = 100 kohm, R24 = 1, 6 kohm, R25 = 10 kohm and the values of the capacitors are C23 = 10 mF, C10 = C1 1 = C2 = C4 = C5 = C7 = 100 nF.
9. Dispositivo según la reivindicación 7, en el que los valores de las resistencias son R1 '=R2'=100 ohm, R3'=100 kohm, R24'=1 ,6 kohm, R25'=10 kohm y los valores de los condensadores son C23'=10 mF, C10'=C1 1 '=C2'=C4'=C5'=C7'=1 OOnF. 9. Device according to claim 7, wherein the values of the resistors are R1 '= R2' = 100 ohm, R3 '= 100 kohm, R24' = 1, 6 kohm, R25 '= 10 kohm and the values of the Capacitors are C23 '= 10 mF, C10' = C1 1 '= C2' = C4 '= C5' = C7 '= 1 OOnF.
10. Dispositivo según la reivindicación 1 , en el que los medios para acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprenden un filtro paso-bajo (R51 , C52) aplicable a la señal de tensión Vbat medida y un comparador (21 ). 10. Device according to claim 1, wherein the means for conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprise a low-pass filter (R51, C52) applicable to the signal of Vbat measured voltage and a comparator (21).
1 1 . Dispositivo según la reivindicación 10, en el que: eleven . Device according to claim 10, wherein:
el filtro paso-bajo (R51 , C52) está formado por una resistencia (R51 ) y varios condensadores (C52) conectados en paralelo;  the low-pass filter (R51, C52) is formed by a resistor (R51) and several capacitors (C52) connected in parallel;
el filtro paso-bajo es inicializado mediante dos transistores (53) y un conjunto de resistencias (R);  the low-pass filter is initialized by two transistors (53) and a set of resistors (R);
dicha señal de tensión Vbat medida se pasa por el filtro paso-bajo para obtener un valor de tensión promedio Vprom; y  said measured Vbat voltage signal is passed through the low-pass filter to obtain an average voltage value Vprom; Y
- dicha tensión promedio Vprom es comparada en el comparador (21 ) a la señal de tensón Vbat medida, siendo la salida del comparador (21 ) la señal de tensión acondicionada Vbat_acond. - said average voltage Vprom is compared in the comparator (21) to the measured voltage signal Vbat, the comparator output (21) being the conditioned voltage signal Vbat_acond.
12. Dispositivo según cualquiera de las reivindicación 10-1 1 , en el que la resistencia R51 tiene un valor de 10 kohm y los condensadores C52 un valor de 2mF. 12. Device according to any of claims 10-1 1, wherein the resistor R51 has a value of 10 kohm and the capacitors C52 have a value of 2mF.
13. Dispositivo según cualquiera de las reivindicaciones 1 -1 1 , en el que los medios para ajustar la señal de corriente en el dominio del tiempo a un nivel de carga del elemento de almacenamiento energético (1 ) y para excitar el elemento de almacenamiento energético (1 ) con esta señal de corriente ajustada en el dominio del tiempo comprenden una fuente de corriente (4). 13. Device according to any of claims 1 -1 1, wherein the means for adjusting the current signal in the time domain at a charge level of the energy storage element (1) and for exciting the energy storage element (1) with this current signal set in the time domain they comprise a current source (4).
14. Dispositivo según la reivindicación 13, en el que la fuente de corriente (4) comprende un transistor (44) con una resistencia (R42) conectada entre un drenador (44d) del transistor (44) y una tensión de alimentación, y una resistencia (R43) conectada entre una fuente (44s) del transistor (44) y una puesta a tierra; y además comprende un amplificador (41 ) conectado a una puerta (44g) del transistor en realimentación negativa con la tensión de la fuente (Vs). 14. Device according to claim 13, wherein the current source (4) comprises a transistor (44) with a resistor (R42) connected between a drain (44d) of the transistor (44) and a supply voltage, and a resistance (R43) connected between a source (44s) of the transistor (44) and a grounding; and also comprises an amplifier (41) connected to a gate (44g) of the transistor in negative feedback with the source voltage (Vs).
15. Dispositivo según la reivindicación 14, en el que la resistencia R42 tiene un valor de 10 ohm y la resistencia R43 tiene un valor de 1 ohm. 15. Device according to claim 14, wherein the resistor R42 has a value of 10 ohm and the resistor R43 has a value of 1 ohm.
16. Dispositivo según cualquiera de las reivindicaciones 1 -15, en el que los medios de generación de un estímulo de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado y los medios de transformación de dicho estímulo de corriente i(f) en el dominio de la frecuencia a una señal de corriente en el dominio del tiempo están integrados en los medios de procesamiento y control (7). 16. Device according to any one of claims 1-15, wherein the means for generating a current stimulus i (f) in the frequency domain with a given spectral content and the means for transforming said current stimulus i (f) in the frequency domain to a current signal in the time domain are integrated in the processing and control means (7).
17. Dispositivo según cualquiera de las reivindicaciones 1 -16, en el que el contenido espectral del estímulo de corriente i(f) es configurable a diferentes frecuencias. 17. Device according to any one of claims 1-16, wherein the spectral content of the current stimulus i (f) is configurable at different frequencies.
18. Procedimiento de medida de impedancia (100) de un elemento de almacenamiento energético (1 ), caracterizado por que comprende: 18. Impedance measurement procedure (100) of an energy storage element (1), characterized in that it comprises:
- generar un estímulo de corriente i(f) en el dominio de la frecuencia con un contenido espectral dado; - generate a current stimulus i (f) in the frequency domain with a given spectral content;
transformar dicho estímulo de corriente i(f) en el dominio de la frecuencia a una señal de corriente en el dominio del tiempo;  transforming said current stimulus i (f) in the frequency domain to a current signal in the time domain;
ajustar esta señal de corriente en el dominio del tiempo a un nivel de carga del elemento de almacenamiento energético y excitar el elemento de almacenamiento energético (1 ) con esta señal de corriente ajustada en el dominio del tiempo;  adjust this current signal in the time domain to a charge level of the energy storage element and excite the energy storage element (1) with this current signal adjusted in the time domain;
medir unas señales de tensión y corriente, Vbat, Ibat en el dominio del tiempo del elemento de almacenamiento energético (1 ) y acondicionar dichas señales medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond a un rango dinámico de unos medios de conversión analógico a digital (5);  measure voltage and current signals, Vbat, Ibat in the time domain of the energy storage element (1) and condition said measured signals to conditioned voltage and current signals, Vbat_acond, lbat_acond to a dynamic range of conversion means analog to digital (5);
digitalizar dichas señales de tensión y de corriente acondicionadas, Vbat_acond, lbat_acond, y transformarlas en unas señales de tensión V(t) y corriente l(t) digitalizadas; analizar la energía de dichas señales en el dominio de la frecuencia de tensión V(f) y corriente l(f) digitalizadas en torno a la frecuencia de estímulo; y  digitize said conditioned voltage and current signals, Vbat_acond, lbat_acond, and transform them into digitized voltage V (t) and current l (t) signals; analyze the energy of said signals in the domain of the voltage frequency V (f) and current l (f) digitized around the stimulus frequency; Y
- calcular un vector de impedancia Z(f) como el cociente V(f)/I(f). - calculate an impedance vector Z (f) as the ratio V (f) / I (f).
19. Procedimiento según la reivindicación 18, en el que la etapa de acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprende eliminar la componente continua de, al menos, la señal de tensión Vbat medida mediante un filtro paso-alto (C23, R24). 19. A method according to claim 18, wherein the step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprises eliminating the continuous component of, at less, the Vbat voltage signal measured by a high-pass filter (C23, R24).
20. Procedimiento según la reivindicación 19, en el que la etapa de acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond además comprende amplificar la componente alterna de la señal de tensión no bloqueada por el filtro paso-alto (C23, R24). 20. The method according to claim 19, wherein the step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond further comprises amplifying the alternating component of the voltage signal not blocked by the filter high-pass (C23, R24).
21 . Procedimiento según la reivindicación 18, en el que la etapa de acondicionar dichas señales de tensión y corriente medidas a unas señales de tensión y corriente acondicionadas, Vbat_acond, lbat_acond comprende obtener un valor de tensión promedio Vprom de la señal de tensión medida Vbat, y obtener dicha señal de tensión acondicionada Vbat_acond comparando dicho valor de tensión promedio Vprom con la señal de tensión medida Vbat. twenty-one . Method according to claim 18, wherein the step of conditioning said measured voltage and current signals to conditioned voltage and current signals, Vbat_acond, lbat_acond comprises obtaining an average voltage value Vprom of the measured voltage signal Vbat, and obtaining said conditioned voltage signal Vbat_acond comparing said average voltage value Vprom with the measured voltage signal Vbat.
22. Procedimiento según la reivindicación 21 , en el que dicho valor de tensión promedio Vprom se obtiene pasando la señal de tensión medida Vbat por un filtro paso-bajo (R51 , C52), y la comparación se realiza con un amplificador (21 ). 22. Method according to claim 21, wherein said average voltage value Vprom is obtained by passing the measured voltage signal Vbat through a low-pass filter (R51, C52), and the comparison is made with an amplifier (21).
23. Procedimiento según cualquiera de las reivindicaciones 18-22, que además comprende una etapa adicional de interpretar los datos obtenidos de Z(f) con patrones y diagnosticar el elemento de almacenamiento energético (1 ). 23. Method according to any of claims 18-22, which further comprises an additional step of interpreting the data obtained from Z (f) with standards and diagnosing the energy storage element (1).
PCT/ES2015/070387 2014-05-23 2015-05-14 Device and method for measuring the impedance of an energy storage element WO2015177389A1 (en)

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