CN101917151A - Method for controlling position-less sensor of switched reluctance motor - Google Patents

Abstract

The invention discloses a method for controlling a position-less sensor of a switched reluctance motor, and belongs to the technical field of switched reluctance motor control. The method comprises the following steps of: based on the basic characteristic that the inductance of the switched reluctance motor is periodically changed along with a rotor position, establishing a precise inductance mathematical model according to an inductance characteristic curve, and setting an inductance threshold value of a turn-on/turn-off angular position by using the mathematical model; sampling current and end voltage of each phase, and calculating real-time inductance; and comparing the phase inductance calculation value of the current estimation phase with the inductance threshold value of the turn-off angular position of the phase and the inductance threshold value of the turn-on angular position of the next turn-on phase respectively to obtain a turn-off signal of the current estimation phase and a turn-on signal of the next turn-on phase so as to directly acquire a driving signal of each phase and realize the operation of the position-less sensor. The algorithm can realize turn-on/turn-off angle control by adopting a method for directly estimating the driving signal, meets the requirement of motor optimization control, and is simple and convenient to implement.

Description

A kind of method for controlling position-less sensor of switched reluctance motor

Technical field

Invention relates to a kind of method for controlling position-less sensor of switched reluctance motor, belongs to the switched Reluctance Motor Control technical field.

Technical background

For the switched reluctance machines drive system, the positional information that can obtain rotor in real time and accurately is the prerequisite that guarantees motor reliability service and high performance control.Generally adopt shaft position detectors such as outer dress photoelectric type or Mageneto-sensitive type at present.Adding mechanical position sensor additionally increases the volume of motor, has increased the motor machining complexity, greatly reduces switched reluctance machines advantage simple in structure, and the reliability when having reduced machine operation, has increased cost.Therefore, explore practical indirect position probing scheme and have crucial researching value.

Up to now, the various countries scholar has done big quantity research to this problem from multi-angle, has proposed multiple indirect position probing scheme.Roughly can be divided into following 5 classes.

1) current waveform detection method.The current waveform detection method that people such as Britain scholar Acamley propose, it is no location detecting technology the earliest, its basic thought is: the rotor-position of SRM has determined the incremental inductance of winding, and incremental inductance has determined the rate of change of phase current, therefore can estimate rotor position information according to phase current.

2) electric current-magnetic linkage method.The basic thought of this method is based on the saliency of switched reluctance machines, different rotor-position correspondences different electric currents-magnetic linkage curve, relation between electric current, magnetic linkage, the position three is set up a look-up table and it is left in the internal memory, by calculating the magnetic linkage of winding in real time, the winding current that obtains with sampling just can obtain corresponding rotor position information.Development along with Based Intelligent Control, more and more scholars is applied to fuzzy control and neural network method the information of detection rotor position, can simulate relation between electric current, magnetic linkage, the position by fuzzy control and neural network method, the current value that obtains by the magnetic linkage that calculates in real time and sampling obtains the positional information of rotor reality then.

3) signal excitation and modulation method.This method is to obtain positional information by the method for being carried out signal excitation or modulation the free time mutually, injects high-frequency impulse mutually in the free time of motor, and the current waveform of its output has reflected the information of the instantaneous inductor of winding, thereby just can obtain the positional information of rotor.

4) additional electrical element method.At additional some electric device in the appropriate location of SRM inside, the information of utilizing these electric devices to export is come the position of detection rotor, and the electric device that is added can be inductance coil, electric capacity plate etc., is called interpole coil detection method, additional capacitor detection method etc.

5) basic thought of observer method is a state equation of setting up motor according to the electromagnetic property and the mechanical property of motor, select suitable state variable (as rotating speed, position angle, magnetic linkage etc.), and input variable (voltage) and output variable (electric current), set up the state observer that is determined by the motor body parameter, by detecting the position angle that motor phase voltage and phase current can estimate rotor.

More than these schemes the pluses and minuses and the scope of application are respectively arranged.Wherein, signal excitation and modulation method mainly are applicable to the situation of low rate start, the ruuning situation of low speed during current waveform detection method and additional electrical element method are applicable to, and electric current-magnetic linkage method and observer method mainly are applicable to situation at a high speed.

Traditional position-sensor-free method that is applied to high speed is mainly based on the magnetic linkage or the inductance characteristic curve of motor, according to the non-linear relation of magnetic linkage or inductance and rotor position angle, by tabling look-up or the method for non-linear observation model is obtained rotor position information; Perhaps set up the magnetic linkage threshold values of scram position, obtain drive signal by method with the threshold values comparison by simplifying the magnetic linkage method.Wherein table look-up, the method purpose of nonlinear model and Based Intelligent Control is to obtain continuous rotor-position signal, but if the precision of guarantee estimating, control algolithm is relative complex then, takies more software and hardware resources.The purpose of simplifying the magnetic linkage method is the drive signal that directly obtains each phase of motor, though this algorithm control is simple, it considers to adopt scram position magnetic linkage threshold values, and motor can only operate in conduction mode in turn, therefore has significant limitation.

Summary of the invention

The problem to be solved in the present invention is:

Proposing does not a kind ofly need direct estimation continuous position signal, and only needs to estimate in real time the position-sensor-free method of each phase drive signal, overcomes traditional position-sensor-free method algorithm complexity, software and hardware resources occupancy height, and problem such as the working region is limited.

The present invention adopts following technical scheme for achieving the above object:

1.) FEM (finite element) calculation or experiment measuring switched reluctance machines inductance characteristic data;

2.) utilize step 1.) the inductance characteristic data that provide, set up the nonlinear model of inductance;

3.) real-time each phase current of sense switch reluctance motor and terminal voltage, each phase current of DSP sampling switch reluctance motor and terminal voltage are by each phase magnetic linkage of digital integration compute switch reluctance motor;

4.) the phase magnetic linkage is obtained real-time phase inductance divided by phase current;

5.) current conducting is the estimation phase mutually, in estimating mutually set by step 4.) the phase inductance value calculated, will open/close angle of rupture substitution simultaneously by step 2.) calculating inductance dynamic thresholding in the Mathematical Modeling that obtains;

6.) with step 5.) in estimate mutually in the inductance calculated value respectively with next conducting mutually the turn-on angle position and the inductance valve system of two positions, angle of rupture position, pass of current conducting phase relatively, if the inductance calculated value is greater than next phase turn-on angle position inductance threshold values, then open next phase by opening phase sequence this moment, if the inductance calculated value then turn-offs current conducting phase greater than closing angle of rupture position inductance threshold values;

Can obtain the drive signal of each phase of motor according to above step, thereby realize electric machine without position sensor control.

The inventive method adopts the method for direct estimation drive signal, can realize opening/closing angle of rupture control, satisfies the needs of motor optimal control, and algorithm is simple and realize that conveniently highly versatile has bigger application prospect.

Description of drawings

Fig. 1 is a switched reluctance machines governing system block diagram;

Fig. 2 is the relation of the three pole reactor and the rotor-position of 12/8 structure model machine;

Fig. 3 is model machine one a phase inductance characteristic curve;

Inductance calculated method flow diagram when Fig. 4 was the motor low cruise;

Inductance real-time computing technique FB(flow block) when Fig. 5 moves for the motor high speed;

Fig. 6 for turn-on angle during for-θ during the motor operation each phase inductance calculate waveform in real time;

Fig. 7 is a kind of method for estimating rotor position of switched reluctance motor without position sensor schematic diagram of the present invention.

Embodiment

The present invention by with the phase inductance calculated value of conducting phase with open/close angle of rupture position inductance dynamic thresholding relatively, open mutually the signal of opening and obtain the cut-off signals of current estimation phase and next, the realization position-sensor-free moves.

Be elaborated below in conjunction with the technical scheme of accompanying drawing to invention:

Fig. 1 is a switched reluctance machines governing system block diagram.The switched reluctance machines governing system mainly is made up of switched reluctance machines (SRM), power inverter, control system (DSP+CPLD), position transducer and electric current and voltage detection and protective circuit etc.Its middle controller is the core of system, and detection signal is gathered, calculated and handles, and finishes relevant control algolithm, thus the output control signal corresponding.Inductance among the present invention calculates and the algorithm of position-sensor-free technology is finished by controller, need not to add additional hardware.Phase current and phase winding voltage are detected by voltage, current sensor (LEM).

Fig. 2 is the relation of the three pole reactor and the rotor-position of 12/8 structure model machine.Shown in figure, the inductance curve is the cycle with 45 degree, and wherein each phase inductance differs 15 degree.If 0 degree angle is A phase stator tooth center line and rotor center line aligned position, 22.5 degree are rotor tooth utmost point center line aligned position.

Fig. 3 is model machine one a phase inductance characteristic curve.The inductance characteristic curve can obtain by the method for utilizing FEM (finite element) calculation or experiment measuring.As shown in the figure, the inductance characteristic curve has characterized the non-linear relation between phase inductance and rotor position angle and the phase current three, and its three-dimensional relationship can be by formula (1) expression,

L＝L(θ，i)(1)

According to the above-mentioned inductance characteristic data that obtain, utilize the method for nonlinear fitting can obtain the nonlinear model of inductance.The more accurate model of studying in the world is based on the inductor models of fourier series match at present.Adopt cosine series that the inductance curve is carried out match herein and obtain the inductor models shown in the formula (2).

$L(\mathrm{\θ},i)=\underset{n=0}{\overset{m}{\mathrm{\Σ}}}{L}_n\left(i\right)\cos ({\mathrm{nN}}_r\mathrm{\θ}+{\mathrm{\φ}}_N)---\left(2\right)$

Here ' N _r' be the rotor number of poles, ' m ' approaches exponent number, ' φ _n' be the phase angle.

Inductance calculated method flow diagram when Fig. 4 was the motor low cruise.

This method inductance calculates principle:

One phase winding voltage equation of switched reluctance machines can be expressed as:

$U_k=R_k{i}_k+L_k\frac{{\mathrm{di}}_k}{\mathrm{dt}}+i_k\frac{{\∂L}_k}{\∂\mathrm{\θ}}\mathrm{\ω}---\left(3\right)$

Because the motor low cruise, the 3rd of following formula i.e. motion electromotive force can be ignored, so the winding voltage equation can be expressed as:

$U_k=R_k{i}_k+L_k\frac{{\mathrm{di}}_k}{\mathrm{dt}}---\left(4\right)$

Because each sampling time of electric current is very short, so following formula can equivalence be:

$U_k=R_k{i}_k+L_k\frac{{\mathrm{\Δi}}_k}{\mathrm{\Δt}}---\left(5\right)$

Therefore inductance can be obtained by following formula

$L_k=\frac{U_k-R_k{i}_k}{\mathrm{\Δi}}\mathrm{\Δt}---\left(6\right)$

Phase current and phase winding voltage are detected and are obtained by voltage, current sensor (LEM) respectively in the formula (9), after conditioning, start the A/D sampling routine in DSP, sampling winding terminal voltage and phase current.

Inductance real-time computing technique FB(flow block) when Fig. 5 moves for the motor high speed.Phase current and phase winding voltage are detected and are obtained by voltage, current sensor (LEM), after conditioning, start the A/D sampling routine in DSP, sampling winding terminal voltage and phase current.Calculate the magnetic linkage size according to the integration formula.Wherein the magnetic linkage expression formula of a phase winding is:

${\mathrm{\ψ}}_k\left(t\right)={\∫}_0^t(v_k\left(t\right)-R_k{i}_k\left(t\right))\mathrm{dt}+{\mathrm{\ψ}}_k\left(0\right)---\left(7\right)$

ψ wherein _kBe k phase winding magnetic linkage, v _kBe k phase winding terminal voltage, R is a k phase winding equivalent resistance, i _kK phase winding electric current.Use numerical integrating, following formula can be dispersed turns to:

${\mathrm{\ψ}}_k\left(n\right)=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}[v_k\left(n\right)-R_k{i}_k\left(n\right)]T+{\mathrm{\ψ}}_k\left(0\right)---\left(8\right)$

Wherein T is the sampling period, the some number of N for measuring, and n is the n measurement point.

Can obtain inductance value according to the relational expression between inductance and the magnetic linkage.

ψ(θ，i)＝L(θ，i)i (9)

$L(\mathrm{\θ},i)=\frac{\mathrm{\ψ}(\mathrm{\θ},i)}{i}---\left(10\right)$

Fig. 6 for turn-on angle during for-θ during the motor operation each phase inductance calculate waveform in real time.Is example as figure mutually with A, and open θ this moment in advance, if the angle of flow is θ _c, closing the angle of rupture so is θ+θ _c

Fig. 7 is a kind of method for estimating rotor position of switched reluctance motor without position sensor schematic diagram of the present invention.Feature of the present invention is based on the inductance of switched reluctance machines with the periodically variable basic characteristics of rotor-position, by with the phase inductance calculated value of conducting phase with open/close the inductance dynamic thresholding comparison of angle of rupture position, and the cut-off signals that obtains current estimation phase is opened mutually the signal of opening with next, thereby directly obtain the drive signal of each phase, realize the position-sensor-free operation.Concrete enforcement principle as shown in Figure 7.

One. utilize FEM (finite element) calculation or experiment measuring model machine inductance characteristic curve, and utilize this inductance characteristic data, set up inductance nonlinear model L (θ, i).The nonlinear model of inductance can adopt the fourier series fitting method to obtain, can be by formula 2 expressions.

By shown in Figure 2, the inductance curve is the cycle with 45 degree, wherein each phase inductance phase difference 15 degree.Phase difference also is 15 degree between the so adjacent phase turn-on angle.If the motor phase sequence is B-A-C-B, establishing the current phase turn-on angle of opening is θ _Bon, the pass angle of rupture is θ _Boff, then other phase turn-on angle and the pass angle of rupture can be expressed as

θ _Aon＝θ _Bon+15° (11)

θ _Con＝θ _Bon+30° (12)

θ _Aoff＝θ _Boff+15°(13)

θ _Coff＝θ _Boff+30°(14)

Each the phase turn-on angle and the pass angle of rupture are brought in the inductor models (2), can obtain corresponding threshold values signal, be respectively: L (θ _Aon, i), L (θ _Aoff, i), L (θ _Bon, i), L (θ _Boff, i), L (θ _Con, i), L (θ _Coff, i).There is following relation between them:

L(θ _Aon，i)＝L _B(θ _Bon+15°，i _B)(15)

L(θ _Con，i)＝L _A(θ _Aon+15°，i _A)(16)

L(θ _Bon，i)＝L _C(θ _Con+15°，i _C)(17)

L(θ _Aoff，i)＝L _A(θ _Aoff，i _A) (18)

L(θ _Boff，i)＝L _B(θ _Boff，i _B) (19)

L(θ _Coff，i)＝L _C(θ _Coff，i _C) (20)

According to above-mentioned relation, inductance threshold values (the conducting phase sequence is B-A-C-B) can be set as follows:

For the B phase, being provided with relevant angle of rupture position inductance threshold values to be L (θ _Boff, i), the open position inductance threshold values of A phase is L _B(θ _Bon+ 15 °, i).

For the A phase, being provided with relevant angle of rupture position inductance threshold values to be L (θ _Aoff, i), the open position inductance threshold values of C phase is L _A(θ _Aon+ 15 °, i).

For the C phase, being provided with relevant angle of rupture position inductance threshold values to be L (θ _Coff, i), the open position inductance threshold values of B phase is L _C(θ _Con+ 15 °, i).

Two. detect each phase current and terminal voltage in real time, DSP sample each phase current and terminal voltage utilize the described method of above-mentioned Fig. 4 and Fig. 5 to calculate real-time inductance value.

Three. mutually as estimating phase, a method scram position inductance threshold values that current estimation phase is set is opened mutually turn-on angle position inductance threshold values with next set by step in estimation mutually with conducting; While is the inductance value of two methods calculating set by step.Estimate with the inductance calculated value respectively with next two positions of pass angle of rupture inductance valve system of opening turn-on angle and current estimation phase mutually relatively, if the inductance calculated value is greater than the turn-on angle position inductance threshold values of next phase, then open next phase by opening phase sequence this moment, if the inductance calculated value then turn-offs current conducting phase greater than the relevant angle of rupture position of current estimation inductance threshold values.

The concrete decision logic of said method as shown in Table 1.

Table one drive signal decision logic table

Current estimation phase	Inductance relatively	Logical process	Determine to estimate phase
				C	L＞L C(θ Con+15°，i)	Open the B phase	C，B
C，B	L＞L C(θ Coff，i)	Turn-off the C phase	B
				B	L＞L B(θ Bon+15°，i)	Open the A phase	B，A
B，A	L＞L B(θ Boff，i)	Turn-off the B phase	A
				A	L＞L A(θ Aon+15°，i)	Open the C phase	A，C
A，C	L＞L A(θ Aoff，i)	Turn-off the A phase	C
				…	…	…	…

According to the conducting phase sequence, if estimate to be the C phase mutually this moment, if L＞L _C(θ _Con+ 15 °, i), then open the B phase, determine that simultaneously C, B are mutually for estimating phase; If L＞L _C(θ _Coff, i), then turn-off the C phase, determine that simultaneously B is mutually for estimating phase; If L＞L _B(θ _Bon+ 15 °, i), then open the A phase, determine that simultaneously B, A are mutually for estimating phase; If L＞L _B(θ _Boff, i), then turn-off the B phase, determine that simultaneously A is mutually for estimating phase; If L＞L _A(θ _Aon+ 15 °, i), then open the C phase, determine that simultaneously A, C are mutually for estimating phase; If L＞L _A(θ _Aoff, i), then turn-off the A phase, determine that simultaneously C is mutually for estimating phase.Can obtain the drive signal of each phase of motor according to above step, thereby realize electric machine without position sensor control.

The method that this algorithm adopts the direct estimation drive signal can realize opening/close angle of rupture adjustable control, satisfies the needs of motor optimal control, and algorithm is simple and realize that conveniently highly versatile has bigger application prospect.

Claims (1)

1. a method for controlling position-less sensor of switched reluctance motor is characterized in that comprising the steps:

1.) FEM (finite element) calculation or experiment measuring switched reluctance machines inductance characteristic data;

2.) utilize step 1.) the inductance characteristic data that provide, set up the nonlinear model of inductance;

3.) real-time each phase current of sense switch reluctance motor and terminal voltage, each phase current of DSP sampling switch reluctance motor and terminal voltage are by each phase magnetic linkage of digital integration compute switch reluctance motor;

4.) the phase magnetic linkage is obtained real-time phase inductance divided by phase current;

5.) current conducting is the estimation phase mutually, in estimating mutually set by step 4.) the phase inductance value calculated, will open/close angle of rupture substitution simultaneously by step 2.) calculating inductance dynamic thresholding in the Mathematical Modeling that obtains;

6.) with step 5.) in estimate mutually in the inductance calculated value respectively with next conducting mutually the turn-on angle position and two positions, angle of rupture position, pass inductance valve system of current conducting phase relatively, if the inductance calculated value is greater than next phase turn-on angle position inductance threshold values, then open next phase by opening phase sequence this moment, if the inductance calculated value then turn-offs current conducting phase greater than closing angle of rupture position inductance threshold values;

Can obtain the drive signal of each phase of motor according to above step, thereby realize electric machine without position sensor control.

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