DE3736244C2 - - Google Patents

Description

The invention relates to a climate control device with a Central control device according to the preamble of claim 1.

A control device is known from WO 87/04 275 A1 known for central control and monitoring decentralized irrigation systems, which record measurement data and send to the central control devices and from receive default signals for valve confirmations there and accordingly emit control signals. It is only a central one Broadcast station with great performance and range provided and the battery-powered receiving stations are constantly full energized and according to the necessary range with high Transmission power and with high reception amplifier expenditure equipped what a corresponding relatively high Battery power consumption caused.

Furthermore, from "Siemens Energy and Automation 8" 1986, issue 1, pp. 40-41 is a control device of an air conditioner known, which contains an optoelectronic receiving circuit, of optical control signals within range of one edge-operated control device, the one contains electro-optical transmitter, can be fed. The The control device works on a mains supply and is always on ready to receive. Central coordination of the controls multiple climate control devices does not do what increased energy consumption results when neighboring air conditioners  regulate differently or in particular oppositely.

Furthermore, from "Siemens Energy Technology 6" (1984) Issue 3, P. 170, an infrared data transmission for a mobile Data acquisition between battery-operated handheld terminals as well as mobile, with a 24 V electrical system operation and its central network-powered computer known, the computer communicates with the terminals with a range of up to 40 m. A building-wide climate control is therefore not provided for not possible.

Furthermore from "Der elektromeister + deutsches Elektrohandwerk" de22 / 86 - 1659, infrared remote control devices known with the manually operable control devices an opto-electronic 4-channel transmitter constantly Ready-to-receive, line-powered light signal receivers can be acted upon, which the received signals in or implement switch-off signals.

Furthermore, from "Siemens Energie & Automation 7" (1985) booklet 2, p. 198, a central control device for Building management technology, especially for climate control, known, from wired control signals to mains powered Control devices are transmitted to the Flow control on radiators and air conditioners for the purpose Temperature control in the vicinity of the same serve. The wired signal transmission to the controllers on radiators has the disadvantage that especially in public buildings, e.g. B. Schools, the signal lines are easily destroyed can.

The object of the invention is a climate control device with remote controlled local battery operated control devices of the type mentioned at the beginning  to improve such that they have a low battery power requirement exhibit.

The solution to the problem is in the characterizing part of the Claim 1 specified.

Advantageous designs are in the subclaims specified.

The controller and its receiver are powered either via a long-term battery or advantageously via a solar cell generator with a storage battery. The power consumption of the regulator circuit is by several Measures so low that a conventional long-life battery several years or a solar cell arrangement with a few Square centimeters of active area when irradiated with conventional Sufficient ambient light for operation.

The energy saving measures consist of:

• - The light signal amplifier becomes very high-resistance and operated non-linear, which is why a purely digital, pulse-based signal evaluation takes place.
• - The various circuit parts, including the Solar power supply, only then and only powered for as long as this for the individual function is required.
• - The controller circuit is completely self-adjusting, so that they are each within the full work area of the actuator acted upon by it, in addition, unnecessary actuation processes in one Dead zone or in a stop area in which excessive power consumption would be avoided.  
• - The actuator is self-locking and therefore does not require any Holding current.
• - The transmission procedure and signaling is advantageous to a low signal level and short signal duration and high transmission frequency as well as high Immunity to ambient light and sufficient transmission capacity for several hundred local controller.

Advantageous embodiments of the control devices and their detailed circuits and devices are described with reference to FIGS . 1 to 9.

Fig. 1 block diagram of the overall control device;

Fig. 2 block diagram of a local control device;

Fig. 3 detailed circuit diagram for Fig. 2;

Fig. 4 circuit diagram of the light signal amplifier;

Fig. 5 waveforms of the light signal amplifier;

Fig. 6 circuit diagram of the solar charger;

Fig. 7 structure of the actuating device;

Fig. 8 end view of Fig. 7;

Fig. 9 dependence of the motor current on the travel.

Fig. 1 is an overview diagram showing a control device. The central control device (ZST) is formed by a program-controlled computer, to which programs and desired operating states of the local control device ( RE 1 , - RE 3 ) are fed by an input device (E) , and to an output device (A) operating states and local measured values of the local control devices. The central control device (ZST) is connected via a data transmission network (DUE) , which is of two-wire design, to photoelectric coupling devices (LKV 1 , - LKV 3 ), each consisting of a line-side transmission and reception device (FK 1 , - FK 3 ) and one Transmit and receive circuit (RK 1 , - RK 3 ) in the local controller (RE 1 , - RE 3 ), each with an intermediate optical transmission link.

Fig. 2 is a line diagram showing a local control device. It consists of a control computer (ST) with a program and data memory (SP) , on the input side with signals from a timer (CL) , with output signals from an analog-digital converter (AD) and a demodulator (DEM) , which is used to evaluate signals in the receiving circuit ( RK 1 ) serves received light-electric control signals, is acted upon and controls the transmission circuit (RK 1 ), a measuring multiplexer (MUX) and a motor control (MS) of the servomotor ( 6 ) with the gear (BG) on the output side via a modulator (MOD) . In the case of a heating control, the gearbox (BG) is coupled to a flow valve (VM) which controls the flow of the heating or cooling medium in the heat exchanger (HK) , in the area of influence of which a temperature sensor (TS) is arranged, the output signal of which a bridge circuit (BR) is fed to a differential amplifier (VD) which is connected to a first input of the multiplexer (MUX) . In this way, a local control loop can be closed via the control computer (ST) by comparing the measured temperature value with a preset value and accordingly acting on the motor ( 6 ).

A default value for the local controller can be supplied to the control computer (ST) on the one hand by a local setting device (E 1 ) and on the other hand can be supplied by the central control device via the receiving circuit (RK 1 ), the two default values preferably being evaluated additively. It is also possible to enter a default value by setting one of the bridge resistors (RE) .

Instead of a local control loop with external specification, the control loop can also be closed via the central control device in a further operating mode, in that the temperature measurement values are reported to the central control device via the transmission circuits (RK 1 , - RK 3 ) and a comparison is made with the default values there and Corresponding control signals are supplied to the local control computers (ST) and passed on by them to the engine controls (MS) .

The local regulator circuit is supplied with power via a voltage supply device (UVV) which emits a battery voltage (UB) . In order to ensure a high level of measurement accuracy with, on the other hand, extreme battery capacity utilization, which means working in a large supply voltage range of e.g. B. requires 6.5 V to 2.5 V, the supply voltage (UST) of the control computer is stabilized via a voltage stabilizer (UC) to the analog-digital converter (AD) and to the bridge (BR) . In addition, the supply voltage (UST) is fed to a second input of the measuring multiplexer (MUX) , so that it is measured and compared with a limit value, whereupon a corresponding message is sent to the central control or the value of the supply voltage (UST ) is transferred directly to the central control for evaluation and output.

Furthermore, a motor current signal (MI) is led from the motor control (MS) to a third input of the multiplexer (MUX) , so that the motor current strength can be evaluated in terms of control.

In order to minimize the current requirement of the regulator circuit, the battery voltage (UB) is fed directly to a regulator starter circuit (RS) , which has a very low internal power consumption, and the supply voltage (UST) , which is only periodically passed on briefly, is fed to the regulator device and a receiver starter circuit (ES) , which in turn only applies the transmitter-receiver circuit (RK 1 ) and a frequency discriminator ( FD) with a receiver supply voltage (UES) and supplies a discriminator time signal (DZS) to the discriminator (FD) .

In Fig. 3, details are shown of the local regulator circuit. The controller starter circuit (RS) consists of a clock generator (G 1 ), which generates pulses of relatively low frequency, which act on a coaster counter (Z 4 ), so that this via the OR gate (OG) and a downstream flip-flop (FF 1 ) in switches on the supply voltage (UST) according to the capacity of the coaster counter (Z 4 ) at large time intervals. In addition, the clock generator (G 1 ) triggers a sequence of two timing elements (M 1 , M 2 ), each of which supplies the receiver supply voltages (UES) and the discriminator time signal (DZS) for a short time via the inverting AND gates (N 1 , - N 3 ) . The light signal amplifier (LEV) of the receiving circuit (RK 1 ) or the discriminator counter (Z 1 ) serving as a frequency discriminator is thus supplied. This counts the pulses (LP ) emitted by the light signal amplifier (LEV) while the discriminator time signal (DZS) is present, so that the counter only reaches its end value when the incoming number of pulses of the light pulse signals (LP) within the duration of the discriminator time signal (DZS) exceeds the maximum counter reading. The output signal of the discriminator counter (Z 1 ) acts on an OR gate (OG) , which then switches on the regulator supply voltage (UST) , with which the control processor (STP) and the demodulator (DEM) and the other connected circuit parts are supplied.

At the end of the control function to be executed, the control processor (STP) switches off the flip-flop (FF 1 ) and thus the supply voltage (UST) .

An additional power saving is achieved in that the timers (M 1 , M 2 ) and the discriminator counter (Z 1 ) are switched off via the output signal of the inverter (N 1 ) in the pause times when there is no supply voltage (UST) .

The overall current consumption of the circuit is kept particularly low by using a frequency modulation method which requires simple digital switching means for demodulation. It is provided that a first pulse repetition frequency of e.g. B. 120 kHz, a second binary state representing a second lower pulse train fundamental frequency of z. B. 100 kHz and a second binary state representing third pulse repetition frequency of z. B. 50 kHz to use. These pulse repetition frequencies are distinguished from one another by means of the demodulator (DEM) . Serve this purpose, the two presettable counters (Z 1, Z 3), one of which is a Uhrtaktzähler (Z 2) and the other a light pulse counter of the light pulse signals (LP) (Z 3). The counter values are evaluated by the control processor (STP) each time the clock pulse counter (Z 2 ) triggers an interrupt with its overflow signal and interrupts the interim standby status, in accordance with an agreed bit time grid, the bit sequence of the binary states being determined from the binary states and an agreed evaluation of the respective bit sequence is carried out.

The first pulse repetition frequency is only used for switching on. By means of the frequency discriminator (FD) , the time grid is assigned to the following evaluation, so that the control computer (ST) is not switched on for an unnecessarily long time due to interference signals and a long synchronization pulse sequence is not required. The counters (Z 2 , Z 3 , Z 5 ) are only released when necessary by switching off the blocking signal (EN) from the control processor (STP) , so that they only consume activity current. When the blocking signal (EN 1 ) is switched off, a monitoring timer (M 3 ) is released during the counting processes, which is retriggered by the light pulse signal (LP) on the input side and whose expiration time corresponds to a predetermined maximum pulse interruption time, after which an interrupt input of the control processor (STP) is activated with its output signal, the evaluation of which detects a long pulse sequence interruption, which can be used as a fault message or for synchronization.

The transmission of messages from the control processor (STP) is carried out via a presettable modulator counter (Z 5 ), which is acted on by the clock pulse of the quartz-controlled timer (CL) and according to the pulse durations provided for one or the other binary state to be transmitted by the control processor ( STP) is preset. The output signal of the modulator counter (Z 5 ) is delivered to the light pulse transmitter (LS) . To prevent misinterpretations, it is provided that for the retransmission to the central control device, approximately 20% lower pulse repetition frequencies than the frequencies used by the central control (ZST) , e.g. B. 40 and 80 kHz to use, which are below the discriminator frequency and so can not lead to any unwanted activity with corresponding power consumption in other control processors and demodulators.

The entire circuit shown can consist of individual Components be assembled; but several can Components can be integrated with each other or, if the Processor speed is sufficient, through program functions, e.g. B. counting programs to be replaced.

Through the illustrated power supply needed various circuit parts can be used in practical operation the average power requirement to about 0.5% of the maximum Reduce electricity consumption.

Fig. 4 shows a light signal amplifier (LEV), which is constructed power saving and stray-light-insensitive, the high frequency optical pulse signals in a relatively wide range of sensitivity, ie even when the aging, dusting and deviation of the optical axes of the light transmitters and receivers, amplifies, and in electric light signal pulses (LP) converts with normal switching level. The four amplifier stages (V 1 , - V 4 ) are each capacitively coupled and provided with impedance converters at the output. The coupling time constants are a multiple of the pulse sequence times, but they are small compared to the usual pulse sequence times of the frequencies from 100 to 300 Hz of surrounding fluorescent tube lighting, so that this interference lighting does not generate any output signals. In addition, the photodiode (LD) is provided with a relatively low-impedance terminating resistor (RA) , and a discharge diode (D 1 ) is fed back to the input of the first amplifier stage (V 1 ), so that the amplifier quickly settles. The signal (LS ) occurring at the output of the fourth amplifier stage (V 4 ), which is strongly distorted by the amplifier time constants and possibly overdrive, is then converted into the digital light pulse signal (LP) in a coupled pulse shaper (IF) even if the threshold hysteresis is shifted thermally which however u. U. has different pulse widths.

In Fig. 5 are the waveforms of the light transmitter (QL) and the signal (LS 1 ) and the light pulse signal ( LP 1 ) for the case of low incidence and high switching thresholds (VTH 1 , VTH 2 ) and for the case of high incidence of the signal (LS 2 ) and the light pulse signal (LP 2 ) at low switching thresholds (VTH 3 , VTH 4 ) shown. Despite very different conditions, there is only a different pulse length and a different relative position of the light signal pulse (LP 1 , LP 2 ) to the respective input pulse from the light transmitter, which is, however, meaningless in the subsequent evaluation method of frequency determination shown.

This circuit can be used, for example, for a Transmission frequency of 130 kHz with a light emitting diode current of 100 mA at a distance of 1 m from the receiver is normal Generate receive signal, even if the supply voltage is in the lower tolerance range.

In Fig. 6, the voltage supply device (UVV) , namely a solar converter for charging the battery (AC) is shown, the battery voltage (UB) of z. B. delivers 4.2 V. So that only a few z. B. 1 or 2 solar cells (DS) must be connected in series, the low output voltage is raised by a clock-controlled flyback converter (SW) to the charging voltage of the battery (AC) . So that this flyback converter (SW) does not constantly consume power, even if there is not enough solar power available, a test circuit is provided that only releases the control pulses of the flyback converter (SW) when there is sufficient solar power available.

The pulse generator (G 2 ) periodically switches a measuring resistor (RM) from the battery voltage (UB) to the solar cells (DS) , the measuring voltage being fed via a coupling diode (D 2 ) to a threshold value detector (SD) , the output signal of which is a flip-flop (FF ) sets, the output of which starts a pulse generator (IG) which acts on the flyback converter (SW) . The threshold of the threshold value detector (SD) is expediently set so high that the power output by the flyback converter (SW) for charging the battery exceeds its operating power. In this way, the power dissipation of the flyback converter (SW) , which would correspond to approximately half the useful power in continuous operation, can be reduced to below 0.3% by the demand operation.

This circuit can also be advantageous in other applications be used.  

Fig. 7 shows an actuating device which is acted upon by the engine control. A DC motor ( 6 ) is preferably attached at the end to a bearing frame ( 1 ) and is connected to its shaft ( 61 ) by a driver pin ( 62 ) with a rotatably mounted threaded sleeve ( 3 ) into which a threaded bolt ( 4 ) is screwed. The threaded bolt ( 4 ) carries lateral flats ( 41 ), which form an anti-rotation device with ridges ( 5 a , 5 b) on the frame, as shown in FIG. 8. This spindle gear can be placed on known valve heads of heating devices. Since the known valves have different starting positions and useful strokes, it is advantageously provided that the control signal is automatically adapted to the given control range and its position. The pitch of the spindle drive is selected so that the gear is self-locking.

In Fig. 9, the dependence of the motor current (MI) of the spindle path (WS) is shown, wherein a spring-loaded valve stem is actuated. As long as the spindle does not touch the valve tappet, there is an idle travel (WL) on which there is a relatively low power requirement. In the working stroke (WH) , on the other hand, the motor current increases linearly along the path according to the spring tension, and at the zero point (NPS) of the stroke (WH) , at which the spring preload has to be overcome, and in the end position (EL 2 ), there are relatively steep steps Electricity increases across the way. For automatic adaptation, the entire current characteristic is measured during a spring-tensioning run, with the end of the first steep current rise at the associated first motor current value (MI 1 ) and the beginning of the second steep current rise at the associated second motor current value (MI 2 ) by differential evaluation of current measurements carried out periodically over the duration are determined. At the same time as the mean current strength (MI) , the commutator-related relative current fluctuations, that is to say the current maxima or minima of the current ripple, are continuously determined and counted and the total number of commutator current peaks which were in the working stroke (WH) are ascertained and counted during the run.

A control signal determined in each case for regulation is proportional to a given control signal range to the total number of commutator current peaks determined in converted a number of commutator current peaks, and the Motor control is then based on a given Starting position of the actuator in the corresponding direction energized and with such a duration until through one current flow evaluation a corresponding number of Commutator current peaks have occurred, so that one Control signal corresponding position is reached. This will then assigned a corresponding position value and for the next control process saved as starting position. To this Control is achieved without lost motion, so that current-consuming control vibrations are eliminated. In addition, operate the engine in a wide battery voltage range.

The motor current evaluation takes place in normal operation preferably both with respect to the commutator current peaks also with regard to a steep middle occurring Power outage or power drop, which in the lead the End positions and in return the zero positions are signaled, whereupon a corresponding correction of the stored starting position is done. That way any accumulating position determination Errors, e.g. B. can occur due to commutator interference, eliminated.  

An automatic range determination and adjustment can be also for a stepper motor through a current profile evaluation make, however, is a motor with DC operation especially with strongly fluctuating battery voltage cheaper.

The data transmission method shown can also be instead of for light signals for acoustic or others Use electromagnetic waves advantageously. Instead of the individual photoelectric transmitter and receiver near the Controller can also generate a centrally generated modulated light signal via the glass fiber to a central receiver for evaluation be transferred back.

The central control device serves in the case of a Building climate control in a known manner a specification of Room temperatures according to their time use and taking into account the respective foreign and Building conditions. A central optimization of the control taking into account the given time constant is particularly advantageous if the temperatures, which are measured in the area of the individual controllers to which Central control device are transmitted. These Advantageously, transmission only takes place on demand Requested by the central controller or when there is a change has occurred, so that no unnecessary transmission power on the Controller side is consumed.

The frequency of the clock generator, the capacities of the counters and the frequency of the clock will be the requirements according to the control accuracy or frequency detection chosen.

Claims (17)

1. Climate control device with a central control device (ZST) to which coupling devices (LKV 1 , - LKV 3 ) are connected via a data transmission network (DUE) , each of which consists of a transmitting and receiving device (FK 1 , - connected to the data transmission network (DUE) FK 3 ) and a spatially separate transmission and reception circuit (RE 1 , - RE 3 ), the transmission and reception circuit being arranged in a local control device which is fed by a battery voltage supply device (UVV) , characterized in that its battery voltage (UB) is fed directly to a controller starter circuit (RS) which contains a pulse generator (G 1 , Z 4 ) which periodically briefly supplies a supply voltage (UST) to a local control computer (ST) and a receiver starter circuit (ES) which supplies a receiver supply voltage ( UES) of the receiver circuit (RK 1 ) and a frequency discriminator connected downstream of the latter gate (FD) , which applies a control signal to the controller starter circuit (RS) so that it continues to supply the supply voltage (UST) when a reception frequency supplied to the frequency discriminator (FD) by the receiver (RK 1 ) is above a predetermined limit value. 2. Climate control device according to claim 1, characterized in that the receiver starter circuit (ES) contains a timing element (M 2 ) which supplies the frequency discriminator ( FD) with a discriminator time signal ( DZS) , the duration of which forms the limit value in which a discriminator counter (Z 1 ) Receive signal pulses (LP) from the output of a receive signal amplifier (LEV) of the receiver circuit (RK 1 ) counts. 3. Climate control device according to one of the preceding claims, characterized in that the coupling devices (LKV 1 , - LKV 3 ) work photoelectrically, acoustically or electromagnetically. 4. Climate control device according to one of the preceding claims, characterized in that the control computer (ST) is connected on the input side to an analog digital converter (AD), which is connected on the input side to a measurement signal multiplexer (MUX) , the first multiplexer input of which is connected to a measurement value transmitter, preferably a temperature sensor ( BR, TS, VD) is connected, which is supplied with a stabilized voltage (UC 1 ) via a voltage stabilizer (UC) to which the supply voltage (UST) is applied, and whose second multiplexer input is connected to the supply voltage (UST) and whose third multiplexer input is supplied with a motor current measurement signal (MI) from a motor controller (MS) of a servomotor ( 6 ), which is connected on the output side to the control computer (ST) . 5. Climate control device according to claim 4, characterized in that the control computer (ST) program-controlled periodically switches the multiplexer (MUX) to the second input and compares the digitally converted supply voltage signal (UST) with a limit value and, when it is undershot, a corresponding message to the central control device (ZST) sends. 6. Climate control device according to claim 4, characterized in that the servomotor ( 6 ) via a self-locking gear, preferably a spindle gear ( 3 , 4 ), a spring-loaded media flow valve (VM) , which is connected upstream of a heat exchanger (HK) , and that Control computer (ST) on a start signal switches the multiplexer (MUX) to its third input and continuously applies the motor ( 6 ) in the direction against the restoring spring force, a differential evaluation of the motor current measurement signal (MI) taking place in close succession and thereby the The end of a first steep rise in the mean current (MI 1 ) and the beginning of a second steep rise in the mean current (MI 2 ) is determined and an associated motor control pulse number is determined between the times thus determined, which is assigned to a predetermined actuating range proportional to the one control of the motor ( 6 ), one of the places of the steep current rose is a starting point of the assignment. 7. Climate control device according to claim 6, characterized in that the number of motor control pulses is carried out by ongoing determination and counting of the collector current peaks of the servomotor designed as a direct current motor ( 6 ) of the current measuring signal (MI) . 8 climate control device according to claim 2 to 7, characterized in that the received signal amplifier ( LEV) , a light signal amplifier ( LEV) , consists of several, preferably four, capacitively coupled and provided with output-side impedance converters amplifier stages (V 1 , - V 4 ), on which an optoelectric receiving diode (LD) on the input side, bridged with a terminating resistor (RA) , capacitively connected and on the output side a hysteresis-related pulse shaper (IF) is connected, which supplies an electrical light pulse signal (LP) . 9. Climate control device according to claim 8, characterized in that the electrical light pulse signal (LP) is supplied counting a light pulse counter (Z 3 ), the content of which can be read out by a control processor (STP) of the control computer (ST) and is determined and evaluated at predetermined time intervals . 10. Climate control device according to claim 9, characterized in that one of the control processor (STP) presettable clock pulse counter (Z 2 ) with its overflow signal in the control processor (STP) triggers an interrupt which causes the reading of the light pulse counter (Z 3 ). 11. Climate control device according to claim 8 or 9, characterized in that the evaluation of the respectively read counter reading of the light pulse counter (Z 3 ) is carried out such that a pulse number in a first pulse number range as a first binary state and a pulse number in a second pulse number range as a second binary state is evaluated and in each case a sequence of first or second binary values is evaluated as control information and the occurrence of pulse numbers outside the two predetermined pulse number ranges is evaluated as an error and a corresponding message is preferably then sent to the central control device (ZST) . 12. Climate control device according to one of claims 9 to 11, characterized in that the electrical light pulse signal (LP) is fed to a retriggerable monitoring timer (M 3 ) which, in the absence of the pulses in a predetermined time, which corresponds to a plurality of maximum pulse times, an interrupt in Control processor (STP) triggers, which then synchronizes or terminates the further evaluation of the light pulse signal (LP) depending on a present state. 13. Climate control device according to claim 9 to 12, characterized in that the central control device (ZST) via the transmitting devices (FK 1 , - FK 3 ) sends out a message in each case as a sequence of temporal signal segments of different frequency, preferably the first signal segment approximately 20% higher frequency than a fundamental frequency and the subsequent signal sections each have the fundamental frequency or half the fundamental frequency, the fundamental frequency preferably being 100 kHz. 14. Climate control device according to claim 13, characterized in that the local control devices (RE 1 , - RE 3 ) each emits a message as a sequence of time signal sections with two different frequencies, one being twice as high as the other and the highest of these frequencies is approximately 20% lower than the fundamental frequency, and is preferably 80 kHz. 15. Control device according to claim 14, characterized in that the transmitter (LS) of the local control device (RE 1 ) is acted upon by the output signal of a modulator counter (Z 5 ) which can be preset by the control processor (STP) . 16. Climate control device according to one of the preceding claims, characterized in that the battery voltage supply device (UVV) consists of a solar cell (DS) to which a clock-controlled flyback converter (SW) is connected, which feeds an accumulator battery (AC) which supplies the battery voltage (UB ) delivers, and that a periodically operating measuring circuit (G 2 , RM, SD) is connected to the solar cell (DS) , which only switches on the clock control of the flyback converter when the solar cell current is so high that the operating power loss of the charging device under the current charging power. 17. Climate control device according to claim 16, characterized in that the measuring circuit (G 2 , RM, SD) consists of a pulse generator (G 2 ) which periodically applies a measuring resistor (RM) to the battery voltage (UB) , and that at the The measuring voltage of the solar cell (DS) is led via a coupling diode (D 2 ) to a threshold switch ( SD) which prepares a flip-flop (FF) on the output side, which is acted upon by the pulse generator (G 2 ) and whose output is a pulse generator (IG ), which connects the flyback converter (SW) to the solar cell (SD) in a pulse-controlled manner.