CN101902189A - Method for initially positioning and starting switched reluctance motor without position sensor - Google Patents

Abstract

The invention discloses a method for initially positioning and starting a switched reluctance motor without a position sensor, and belongs to the technical field of control of the switched reluctance motor. The method comprises the following steps of: setting an inductance bottom threshold value LLow and an inductance top threshold value LHigh based on the basic characteristic that the inductance of the switched reluctance motor periodically changes with the position of a rotor; injecting short pulses into each phase winding and calculating inductance values according to a phase voltage equation; judging phases which can be currently switched on according to the relation among each phase inductance calculated value and LLow and LHigh and selecting estimated phases of an initial position angle at the same time; and establishing a phase inductance mathematical model to obtain angle information in the selected phases by using the relation between the inductance mathematical model and the inductance calculated values. Though the method, an initial switch-on phase selection signal can be accurately acquired and the initial position angle of the rotor can be calculated at the same time, so the switched reluctance motor can be started and initially positioned without the position sensor, an algorithm is simple and generality is high.

Description

A kind of position-less sensor of switched reluctance motor initial alignment and starting method

Technical field

Invention relates to a kind of position-less sensor of switched reluctance motor initial alignment and starting method, belongs to the switched Reluctance Motor Control technical field.

Background technology

For switched reluctance motor system, rotor position information is the prerequisite of its reliability service and high performance control in real time and accurately.In practical application at present, general shaft position sensor or other detection type position detectors of adopting obtains positional information, system cost and complexity have not only been increased, reduced the whole system reliability of operation simultaneously, especially under harsh service conditionss such as some high temperature, high speed and oil pollution environment, the work of conventional position sensor is restricted, thereby has limited the scope of this type motor application, makes its high temperature resistant, suitable proper property at a high speed not find full expression.Therefore, how the position of substitution transducer overcomes the deficiency that adopts position transducer to bring, and explores practical position-sensor-free technology and has crucial researching value.Over nearly 20 years, the various countries scholar has carried out a large amount of research at this problem from a plurality of angles, has proposed multiple no position technique scheme.Typical method has the pulse injection method, based on the modulating-coding technology, and based on the current waveform monitoring scheme, mutual voltage scheme, magnetic linkage/current method and observer scheme, and, search coil technology and based on scheme of Fuzzy Neural-network Control etc. based on inductor models.These schemes have all directly or indirectly utilized instantaneous phase inductance change information to come the indirect detection rotor-position, and separately the service conditions and the scope of application are arranged, and its pluses and minuses are respectively arranged.During the various countries scholar mainly concentrates on position-less sensor of switched reluctance motor research, low-speed range, still locate still to be in initial period for the no position technique research in rotating speed commentaries on classics up to ten thousand stage.Along with intelligent control technology, power electronic technology, digital signal processing technology rapid development, high performance of control scheme and high performance digital signal processor make realizes that various complicated algorithms and more accurate no position technique become possibility.The research of SRM position-sensor-free still is in the laboratory development in the world at present, does not still have Related product and comes out the market prospects light of high performance no position technique switched reluctance machines.

When rotor was static, if the initial position message of obtaining is inaccurate, the initial conducting that tends to lead to errors was judged mutually, even is caused the motor counter-rotating.And under some concrete occasion, be not allow the motor counter-rotating when for example some elaborate servo transmission devices start, if the switched reluctance machines of position-sensor-free is applied to these fields, initial position detects and the accurate initial conducting of judgement problem mutually with regard to solving.Therefore, the nothing of position-less sensor of switched reluctance motor is reversed to start and is just seemed particularly important, but at present on this problem, the technical literature that research is relevant is also few both at home and abroad.

The basic demand that switched reluctance machines starts will have enough big detent torque and less starting current and short start-up time.Therefore the each side factor to be taken all factors into consideration to the research that starts, its reliability of operation will be taken into account when on hardware and software, optimizing.On position-sensor-free startup problem, in the world, the Texas A﹠amp of the U.S.; More deep research has also been done by the Meiji university of M university and Japan on position-sensor-free startup problem, the method that they propose is simply novel, and accuracy of detection is also higher relatively.The former does the phase relation of each phase inductance with subregion, utilize the phase current logical relation of winding in each zone, determine initial conducting phase, but this method does not solve the pinpoint problem of initial position, the detection error of electric current interface point can obtain the wrong signal of selection mutually, even causes counter-rotating.The latter is on the basis of inductance subregion, phase inductance is approximately sinusoidal handles, and carries out vector according to the phase inductance phase relation and synthesizes, thereby calculate initial position angle more accurately, judges the angle The corresponding area again, determines initial conducting phase.Though this method thinking is ingenious, though the inductance curve becomes cyclic variation, it is not standard sine that its characteristics that do not line up position inductance flat site broad cause the inductance curve, and this method of estimation error is bigger.The present domestic Nanjing Aero-Space University that has, the research of colleges and universities such as the Central China University of Science and Technology.The basic thought of its position probing all is in the above winding injected pulse of two-phase, calculates the initial position angle of rotor by the corresponding relation between detection phase current and the inductance.

Summary of the invention

The problem to be solved in the present invention is to estimate motor inactive state lower rotor part initial position accurately, judges the conducting phase according to the conducting phase sequence simultaneously, thereby realizes that position-sensor-free does not have the counter-rotating starting.

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

The present invention comprises the steps: for a kind of position-less sensor of switched reluctance motor initial alignment and starting method

1) sets up the inductance Mathematical Modeling;

2) inductance bottom threshold values L is set _LowWith top threshold values L _High

3) inject short-time pulse to each phase winding, utilize phase voltage Equation for Calculating inductance value;

4) according to each phase inductance calculated value and L _LowAnd L _HighMagnitude relationship, judge the current phase of opening, select initial position angle to estimate phase simultaneously;

5) in selected estimation mutually, utilize inductance Mathematical Modeling and inductance calculated value relation to obtain angle information.

The present invention is simple and be easy to realization, can more accurate selection produce the phase of positive torque with respect to traditional no position starting method, and avoid falsely dropping of conducting phase to select.This method can also be determined current rotor physical location simultaneously, thereby realizes accurate initial alignment.

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 a phase static inductance measured curve.

Fig. 4 is for injecting the response wave shape of a short-time pulse.

Fig. 5 be in the one-period after the injected pulse of A phase the waveform of response current.

Inductance real-time computing technique one flow process block diagram when Fig. 6 is static.

Fig. 7 is motor inductance real-time computing technique two flow process block diagrams when static.

Fig. 8 is a kind of position-less sensor of switched reluctance motor initial alignment of the present invention and starting method schematic diagram.

Embodiment

The present invention realizes that according to the relation of inductance and rotor-position initially opening when motor is static judged mutually and initial position of rotor is estimated.

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.

Fig. 3 is a phase static inductance measured curve.The measurement of static inductance adopts instrument HP4284-LRC table directly to measure the inductance value of respective rotor position.Utilize the inductance measured data to adopt the method for curve fit can obtain the Mathematical Modeling of inductance.Adopt fourier series to come the match static inductance herein, the inductance Mathematical Modeling can be expressed as:

$L\left(\mathrm{\θ}\right)=\underset{n=0}{\overset{k}{\mathrm{\Σ}}}{A}_n\cos {\mathrm{nN}}_r\mathrm{\θ}---\left(1\right)$

Fig. 4 is for injecting the response wave shape of a short-time pulse.Open main switch to the winding injected pulse, the pulse period is Δ T, and when switching tube turn-offed, response current reached and is Δ i to the maximum _aFigure 5 shows that in the one-period waveform of response current after the injected pulse of A phase.

Inductance real-time computing technique one flow process block diagram when Fig. 6 is static.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:

${\mathrm{\ψ}}_k\left(t\right)={\∫}_0^t(v_k\left(t\right)-R_k{i}_k\left(t\right))\mathrm{dt}+{\mathrm{\ψ}}_k\left(0\right)---\left(2\right)$

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:

${\mathrm{\ψ}}_k\left(n\right)=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}[v_k\left(n\right)-R_k{i}_k\left(n\right)]T+{\mathrm{\ψ}}_k\left(0\right)---\left(3\right)$

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 (4)

$L(\mathrm{\θ},i)=\frac{\mathrm{\ψ}(\mathrm{\θ},i)}{i}---\left(5\right)$

This method is owing to introduced integral operation, and phase voltage, phase current detect error, and the variation of winding equivalent resistance, all can influence the precision of calculating, and this method relatively is fit to the magnetic linkage of motor high-speed cruising and estimates.But because when static, phase current is very little when injecting short-time pulse, the pressure drop of winding equivalent resistance is much smaller than pulse voltage amplitude, so the method can be used for the calculating of inductance.But computational process relative complex.

Fig. 7 is motor inductance real-time computing technique two flow process block diagrams when static.

This method inductance calculates principle:

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

$U_k=R_k{i}_k+L_k\frac{{\mathrm{di}}_k}{\mathrm{dt}}+i_k\frac{{\∂L}_k}{\∂\mathrm{\θ}}\mathrm{\ω}---\left(6\right)$

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

$U_k=R_k{i}_k+L_k\frac{{\mathrm{di}}_k}{\mathrm{dt}}---\left(7\right)$

Because the injected pulse cycle is section very, generally about 100 microseconds.Therefore following formula can equivalence be:

$U_k=R_k{i}_k+L_k\frac{{\mathrm{\Δi}}_k}{\mathrm{\Δt}}---\left(8\right)$

Therefore inductance can be obtained by following formula

$L_k=\frac{U_k-R_k{i}_k}{\mathrm{\Δi}}\mathrm{\Δt}---\left(9\right)$

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.

This method realizes more simple than inductance computational methods one, and has degree of precision.When each injected short-time pulse mutually, inductance calculated this method that adopts usually.

Fig. 8 is a kind of position-less sensor of switched reluctance motor initial alignment of the present invention and starting method schematic diagram.Concrete steps associative list one illustrates.

Table one inductance zoned logic table

The inductance logic	The zone	Initial conducting is selected mutually	Initial position is estimated phase
				L a(θ)＞L high	I	B	B，C
L c(θ)≤L low	II	B	A，B
				L b(θ)＞L high	III	C	A，C
L a(θ)≤L low	IV	C	B，C
				L c(θ)＞L high	V	A	A，B
L b(θ)≤L low	VI	A	A，C

1): according to the symmetry of electric machine structure, each phase inductance phase difference 15 degree.By formula (1) as can be known, the inductance function is an even function, therefore for same inductance value within one-period, equation (10) must have two to separate.Therefore to determine initial position, must select two-phase at least as estimating phase.

$L\left(\mathrm{\θ}\right)=\frac{U_k-R_k{i}_k}{\mathrm{\Δi}}\mathrm{\Δt}---\left(10\right)$

2): because it is more smooth not line up the position inductance, size is almost constant, calculates angle in the software and is difficult to differentiate, and therefore must avoid the bottom electrical sensillary area, and select suitable estimation to estimate initial position mutually.As shown in Figure 8, inductance bottom threshold values L is set _LowWith top threshold values L _High, the bottom threshold values L of the corresponding B phase in M point position _Low, this position corresponds to A phase N point, and this inductance is set to top threshold values L _High

3): according to step 2) can obtain following inductance partitioning strategies, as shown in Table 1, work as L _a(θ)＞L _HighThe time, be induction areas I, this moment, initial conducting can be selected the B phase mutually, initial position is estimated be B mutually with C mutually; Work as L _c(θ)≤L _Low, be induction areas II, this moment, initial conducting can be selected the B phase mutually, initial position is estimated be A mutually with B mutually; Work as L _b(θ)＞L _High, be induction areas III, this moment, initial conducting can be selected the C phase mutually, initial position is estimated be A mutually with C mutually; Work as L _a(θ)≤L _Low, be induction areas IV, this moment, initial conducting can be selected the C phase mutually, initial position is estimated be B mutually with C mutually; Work as L _c(θ)＞L _High, be induction areas V, this moment, initial conducting can be selected the A phase mutually, initial position is estimated be B mutually with A mutually; Work as L _b(θ)≤L _Low, be induction areas VI, this moment, initial conducting can be selected the A phase mutually, initial position is estimated be A mutually with C mutually;

4): according to step 3) inductance partitioning strategies, obtained initial conducting phase logic, obtained initial position simultaneously and estimated to select mutually logic.In each inductance subregion, initial position is estimated to be two-phase mutually, satisfies step 1) initial position angle calculation requirement.As shown in Figure 8, being without loss of generality, is example with current location at the θ angle, the corresponding a of each phase inductance difference this moment, and b, c 3 points, its inductance actual value is respectively L _a, L _b, L _c, be in L this moment _a(θ)≤L _LowThe district, promptly area I V can select to open the C phase this moment, and initial position estimates to be B mutually simultaneously, the C phase.In estimating that for selected two phase B and C are mutually, utilize equation in the step 1) (10) in one-period, all can obtain two respectively and separate.If separating, gained is respectively θ _b, θ _B1And θ _c, θ _C1, separating of more above-mentioned gained separated for two that wherein equate and is initial position angle.Be without loss of generality, when rotor was in other position, initial position was estimated and initially the system of selection of conducting phase is consistent therewith.

This method can accurately obtain initial conducting and select signal mutually, can calculate initial position angle of rotor simultaneously, therefore can realize the position-sensor-free starting and the accurate initial alignment of switched reluctance machines, and algorithm is simple, highly versatile.

Claims (1)

1. position-less sensor of switched reluctance motor initial alignment and starting method is characterized in that comprising the steps:

1) sets up the inductance Mathematical Modeling;

2) inductance bottom threshold values L is set _LowWith top threshold values L _High

3) inject short-time pulse to each phase winding, utilize phase voltage Equation for Calculating inductance value;

4) according to each phase inductance calculated value and L _LowAnd L _HighMagnitude relationship, judge the current phase of opening, select initial position angle to estimate phase simultaneously;

5) in selected estimation mutually, utilize inductance Mathematical Modeling and inductance calculated value relation to obtain angle information.

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