CN103762926B - Based on the method for controlling torque of the switch flux-linkage permagnetic synchronous motor of model prediction - Google Patents

Abstract

The invention discloses a kind of method for controlling torque of the switch flux-linkage permagnetic synchronous motor based on model prediction, comprise the steps: that carrying out combination to the switching tube state of motor inverter obtains eight groups of switching vector selector signals; At current time k, under each group inverter switching device vector signal, the p phase winding electric current of prediction subsequent time k+1 obtain the current forecasting value i of d axle and q axle _d ^k+1and i _q ^k+1; The motor torque of prediction subsequent time k+1 with motor magnetic linkage assess the cost function <maths num=" 0001 " > </maths> obtain cost function minimum time inverter switching device vector signal; Definition according to the value of m, control the effective acting time of inverter switching device vector signal when cost function is minimum in the single sampling period, complete the direct torque to switch flux-linkage permagnetic synchronous motor.The accurately control inverter switching vector selector change of the method energy, makes motor torque fluctuate and magnetic linkage fluctuates minimum, and passes through the effective acting time of duty cycle adjustment inverter switching device, thus effectively can reduce the switching frequency of inverter.

Description

Based on the method for controlling torque of the switch flux-linkage permagnetic synchronous motor of model prediction

Technical field

The invention belongs to switch flux-linkage permagnetic synchronous motor technical field, more specifically, relate to a kind of method for controlling torque of the switch flux-linkage permagnetic synchronous motor based on model prediction.

Background technology

Switch flux-linkage permagnetic synchronous motor (Flux-SwitchingPermanentMagnetSynchronousMachine, FSPMSM) design philosophy is the earliest from the research of the people such as Rauch to single-phase doubly salient permanent magnet generator.Because permanent magnetic material performance did not reach reasonable request at that time, cause above-mentioned prototype machine body comparatively large, performance index are poor, therefore do not receiving publicity at that time.Along with the development of science and technology, the performance of permanent magnetic material is greatly improved, this be FSPMSM performance improve established good basis.Along with the people such as Hoang propose 12/10(rotor/stator) pole three-phase FSPMSM, and preliminary emulation demonstrates FSPMSM has the advantages such as good mechanical property, high torque density.The various versions of FSPMSM are at home and abroad extensively studied subsequently.

Since initial 4/2 (rotor/stator) pole, 4/6 pole single-phase permanent flux switching motor are proposed by people such as Rauch, 6/4 pole, 6/5 pole Three phase permanent-magnetic-switch flux linkage motor structure are also proposed by W.Z.Fei.Relevant scholar is to the operation logic of such motor topology, and Mathematical Modeling has carried out finite element analysis, and has carried out deep Electromagnetic Optimum Design to its structure, finally carries out prototype test and verification.Found by research, there is very large cogging torque in the type motor and its back-emf contains very high even-order harmonic, runs bring certain harm to motor.In recent years, even-order harmonic and torque pulsation can be improved by rotor chute optimization, but this measure to a certain degree can reduce back-emf amplitude, and then reduce motor torque etc.Along with deepening continuously of research, the permanent-magnetic-switch flux linkage motor of 12/10 electrode structure is proposed by people such as EmmanuelHoang, and this structure is not only easily dispelled the heat, and has good fault-tolerance and higher weak magnetic energy power.Simultaneously, novel switched magnetic linkage permanent magnet motor structure is constantly suggested in recent years, new electromagnetic optimize method is also constantly developed (W.Xu, J.Zhu, Y.Zhang, andJ.Hu, " Coggingtorquereductionforradiallylaminatedflux-switching permanentmagnetmachinewith12/14poles; " inProc.IEEEIndustrialElectronicsSociety (IECON), Nov.2011, pp.3465-3470.).But up to now, the control method relevant to switch flux-linkage permagnetic synchronous motor also rarely has people to study.

Summary of the invention

For above defect or the Improvement requirement of prior art, the invention provides a kind of method for controlling torque of the switch flux-linkage permagnetic synchronous motor based on model prediction, can accurately change by control inverter switching vector selector, motor torque fluctuation and magnetic linkage is made to fluctuate minimum, and pass through the effective acting time of duty cycle adjustment inverter switching device, thus effectively can reduce the switching frequency of inverter.

For achieving the above object, according to one aspect of the present invention, provide a kind of method for controlling torque of the switch flux-linkage permagnetic synchronous motor based on model prediction, it is characterized in that, comprise the steps:

(1) the switching tube state of motor inverter is combined, obtain eight groups of inverter switching device vector signals;

(2) at current time k, respectively under each group inverter switching device vector signal, the p phase winding voltage of switch flux-linkage permagnetic synchronous motor is gathered p phase winding electric current with rotor velocity ω _r, the p phase winding electric current of prediction subsequent time k+1 wherein, p represents motor A, B and C phase;

(3) respectively under each group inverter switching device vector signal, according to the p phase winding electric current of subsequent time k+1 in conjunction with Stator and Rotor Windings principle of coordinate transformation, obtain the d axle of subsequent time k+1 and the current forecasting value i of q axle _d ^k+1and i _q ^k+1;

(4) respectively under each group inverter switching device vector signal, by the p phase winding electric current of subsequent time k+1 d shaft current predicted value i _d ^k+1with q shaft current predicted value i _q ^k+1, the motor torque of prediction subsequent time k+1 with motor magnetic linkage

(5) respectively under each group inverter switching device vector signal, assess the cost function $G=|T_e^{*}-T_e^{k+1}|+k_1\left|\right|{\mathrm{\&psi;}}_s^{*}|-|{\mathrm{\&psi;}}_s^{k+1}\left|\right|+A\left(\right|T_e^{*}-T_e^{k+N}|+k_1|\left|{\mathrm{\&psi;}}_s^{*}\right|-\left|{\mathrm{\&psi;}}_s^{k+N}\right|\left|\right),$ Obtain cost function minimum time inverter switching device vector signal, wherein, with be respectively the reference value of motor torque and motor magnetic linkage, k ₁for the ratio of nominal torque and specified magnetic linkage, with be respectively the motor torque in K+N moment and the predicted value of motor magnetic linkage, N is positive integer, and A is the regulating error coefficient of N state motor torque and motor magnetic linkage;

(6) define wherein, C _tand C _ψtorque adjustment factor and magnetic linkage adjustment factor respectively, according to the value of m, control the effective acting time of inverter switching device vector signal when cost function is minimum in the single sampling period, to reduce the switching frequency of inverter, complete the direct torque to switch flux-linkage permagnetic synchronous motor.

Preferably, the specific implementation of described step (6) is: in definition current sample period, the effective acting time of voltage vector and the ratio in sampling period are ramp, wherein, and 0≤ramp≤1; As m≤ramp, inverter switching device is failure to actuate, and exports Zero voltage vector; As m>ramp, inverter switching device vector signal when cost function is minimum is as the drive singal of inverter switching device, and the break-make of real-time control inverter switching tube, completes the direct torque to switch flux-linkage permagnetic synchronous motor.

Preferably, in described step (2), the p phase winding electric current of subsequent time k+1 for:

$i_p^{k+1}=i_p^k+\frac{1}{L_p}(u_p^k-R_p{i}_p^k-i_p^k\frac{{\mathrm{dL}}_p}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r-\frac{{\mathrm{d\&psi;}}_{\mathrm{mp}}}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r)*T_s,$

Wherein, L _pfor p phase winding self-induction, R _pfor p phase winding resistance, θ _rfor motor rotor position angle, ψ _mpfor motor p phase permanent magnet flux linkage, Ts is switch periods.

Preferably, in described step (3), the d axle of subsequent time k+1 and the current forecasting value i of q axle _d ^k+1and i _q ^k+1be respectively:

$\left[\begin{array}{c}{i}_d^{k+1}\\ i_q^{k+1}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\cos {\mathrm{\&theta;}}_e& \cos ({\mathrm{\&theta;}}_e-2\mathrm{\&pi;}/3)& \cos ({\mathrm{\&theta;}}_e+2\mathrm{\&pi;}/3)\\ \sin {\mathrm{\&theta;}}_e& \sin ({\mathrm{\&theta;}}_e-2\mathrm{\&pi;}/3)& \sin ({\mathrm{\&theta;}}_e+2\mathrm{\&pi;}/3)\end{array}\right]\&times;\left[\begin{array}{c}{i}_A^{k+1}\\ i_B^{k+1}\\ i_C^{k+1}\end{array}\right],$

Wherein, θ _efor motor in synchrony electrical degree, with be respectively the A phase of subsequent time k+1, B phase and C phase winding electric current.

Preferably, in described step (4), the motor torque of subsequent time k+1 the motor magnetic linkage of subsequent time k+1 ${\mathrm{\&psi;}}_s^{k+1}=(L_d{i}_d^{k+1}+{\mathrm{\&psi;}}_m)+j{L}_q{i}_q^{k+1},$ Wherein, with be respectively the A phase of subsequent time k+1, B phase and C phase motor torque, the p phase motor torque of subsequent time k+1 l _dand L _qbe respectively motor d axle and q axle self-induction, ψ _mfor permanent magnet flux linkage amplitude, L _pfor p phase winding self-induction, θ _rfor motor rotor position angle, ψ _mpfor motor p phase permanent magnet flux linkage.

Preferably, in described step (5), with expression formula be respectively:

$T_e^{k+N}=T_e^k+(N-1)(T_e^{k+1}-T_e^K),$

$\left|{\mathrm{\&psi;}}_s^{k+N}\right|=\left|\right|{\mathrm{\&psi;}}_s^k|+(N-1)|\left|{\mathrm{\&psi;}}_s^{k+1}\right|-\left|{\mathrm{\&psi;}}_s^k\right|\left|\right|,$

Wherein, with be respectively motor torque and the motor magnetic linkage of current time k.

In general, the above technical scheme conceived by the present invention compared with prior art, has following beneficial effect:

1, accurately control inverter switching vector selector change, makes motor torque fluctuate and magnetic linkage fluctuates minimum.Passing ratio integration (PI) adjuster compares reference rotation velocity and real-time rotate speed obtains torque reference, and obtain Reference Stator Flux Linkage further, introduce cost function (CostFunction) as the modulation strategy reducing motor torque fluctuation and magnetic linkage fluctuation, by comparing the size of torque reference and Reference Stator Flux Linkage and prediction torque and prediction magnetic linkage, to minimize for the purpose of cost function (CostFunctionMinimization), choose reasonable voltage vector, real-time control inverter work.

2, by the effective acting time of duty cycle adjustment inverter switching device, when motor torque and motor magnetic linkage change less, inverter switching device is failure to actuate, when motor torque and motor magnetic linkage change greatly, inverter switching device is just devoted oneself to work, and thus effectively can reduce the switching frequency of inverter.

Accompanying drawing explanation

Fig. 1 is induction machine Stator and Rotor Windings coordinate transform schematic diagram;

Fig. 2 is the method for controlling torque flow chart of the switch flux-linkage permagnetic synchronous motor based on model prediction of the embodiment of the present invention;

Fig. 3 is the moment controlling system structural representation of switch flux-linkage permagnetic synchronous motor.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.In addition, if below in described each execution mode of the present invention involved technical characteristic do not form conflict each other and just can mutually combine.

The basic mathematical equation of switch flux-linkage permagnetic synchronous motor is as follows:

$\left[\begin{array}{c}{\mathrm{\&psi;}}_A\\ {\mathrm{\&psi;}}_B\\ {\mathrm{\&psi;}}_C\end{array}\right]=\left[\begin{array}{ccc}{L}_{\mathrm{aa}}& M_{\mathrm{ab}}& M_{\mathrm{ac}}\\ M_{\mathrm{ba}}& L_{\mathrm{bb}}& M_{\mathrm{bc}}\\ M_{\mathrm{ca}}& M_{\mathrm{cb}}& L_{\mathrm{cc}}\end{array}\right]\left[\begin{array}{c}{i}_A\\ i_B\\ i_C\end{array}\right]+\left[\begin{array}{c}{\mathrm{\&psi;}}_{\mathrm{mA}}\\ {\mathrm{\&psi;}}_{\mathrm{mB}}\\ {\mathrm{\&psi;}}_{\mathrm{mC}}\end{array}\right]---\left(1\right)$

Wherein, ψ _a, ψ _band ψ _cbe respectively A, B and C phase magnetic linkage, L _aa, L _bband L _ccbe respectively A, B and C phase self-induction, M _ab=M _bafor A phase and the mutual inductance of B phase, M _ac=M _cafor A phase and the mutual inductance of C phase, M _bc=M _cbfor B phase and the mutual inductance of C phase, i _a, i _band i _cbe respectively A, B and C phase current, ψ _mA, ψ _mBand ψ _mCbe respectively A, B and C phase permanent magnet flux linkage.

Theoretical according to Electrical Motor, the voltage equation that the present invention obtains FSPMSM is further:

$\left[\begin{array}{c}{u}_A\\ u_B\\ u_C\end{array}\right]=\left[\begin{array}{ccc}{R}_s& & \\ & R_s& \\ & & R_s\end{array}\right]\left[\begin{array}{c}{i}_A\\ i_B\\ i_C\end{array}\right]+\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{\mathrm{\&psi;}}_A\\ {\mathrm{\&psi;}}_B\\ {\mathrm{\&psi;}}_C\end{array}\right]---\left(2\right)$

Wherein, u _a, u _band u _cbe respectively A, B and C phase voltage, R _sfor armature winding phase resistance.

The torque equation of tradition permagnetic synchronous motor is:

$T_e=\frac{1}{2}{\left[I\right]}^T\left(\frac{\&PartialD;}{\&PartialD;{\mathrm{\&theta;}}_r}\right[L\left]\right)\left[I\right]+\left(\frac{\&PartialD;}{\&PartialD;{\mathrm{\&theta;}}_r}{\left[{\mathrm{\&psi;}}_{\mathrm{pm}}\right]}^T\right)\left[I\right]---\left(3\right)$

Traditional permagnetic synchronous motor inductance parameters is fixed numbers, not with rotor position angle θ _rchange and change.Because FSPMSM rotor is all double-salient-pole structures, permanent magnet embeds in each stator tooth, and permanent magnet flux linkage, inductance and mutual inductance are all with rotor position angle θ _rchanging and change, is the function of rotor-position.Therefore formula (3) can not directly in order to solve the electromagnetic torque of FSPMSM.

The present invention re-starts magnetic linkage, voltage and the torque equation of FSPMSM under dq axle and ABC axle and derives and illustrate, specific as follows.

Dq axle (two-phase) coordinate system FSPMSM equivalent equation is as follows:

Flux linkage equations:

$\left\{\begin{array}{c}{\mathrm{\&psi;}}_d={\mathrm{\&psi;}}_m+L_d{i}_d\\ {\mathrm{\&psi;}}_q=L_q{i}_q\end{array}\right.---\left(4\right)$

Write as matrix form:

$\left[\begin{array}{c}{\mathrm{\&psi;}}_d\\ {\mathrm{\&psi;}}_q\end{array}\right]=\left[\begin{array}{cc}{L}_d& 0\\ 0& L_q\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]+\left[\begin{array}{c}{\mathrm{\&psi;}}_m\\ 0\end{array}\right]---\left(5\right)$

Wherein, L _dand L _qbe respectively the motor d axle self-induction after dq conversion and q axle self-induction, i _dand i _qbe respectively the electric current transforming to d axle and q axle.Induction machine Stator and Rotor Windings principle of coordinate transformation as shown in Figure 1.

Voltage equation:

$\left\{\begin{array}{c}{u}_d={\mathrm{Ri}}_d+\frac{d{\mathrm{\&psi;}}_d}{\mathrm{dt}}-{\mathrm{\&omega;}}_r{\mathrm{\&psi;}}_q\\ u_q={\mathrm{Ri}}_q+\frac{d{\mathrm{\&psi;}}_q}{\mathrm{dt}}+{\mathrm{\&omega;}}_r{\mathrm{\&psi;}}_d\end{array}\right.---\left(6\right)$

In above formula, u _dand u _qbe respectively the electric moter voltage transforming to d axle and q axle, ω _rfor rotor electrical angular speed.

Torque equation:

$\begin{array}{c}{T}_e=\frac{1}{2}{\left[I\right]}^T\left(\frac{\&PartialD;}{\&PartialD;{\mathrm{\&theta;}}_r}\right[L\left]\right)\left[I\right]+\left(\frac{\&PartialD;}{\&PartialD;{\mathrm{\&theta;}}_r}{\left[{\mathrm{\&psi;}}_{\mathrm{pm}}\right]}^T\right)\left[I\right]\\ =\frac{3}{2}{P}_r{\mathrm{\&psi;}}_m{I}_q-\frac{3}{2}{P}_r(2M_m+L_m)I_d{I}_q\\ =\frac{3}{2}{P}_r[{\mathrm{\&psi;}}_m{I}_q+(L_d-L_q)I_d{I}_q\end{array}---\left(7\right)$

Wherein, P _rrepresent motor number of pole-pairs.Because motor mutual inductance is smaller relative to self-induction, the present invention ignores mutual inductance, and derives to the magnetic linkage under motor ABC axle (single-phase) coordinate system, voltage and torque further, specific as follows.

ABC axle (single-phase) coordinate system FSPMSM equivalent equation:

Flux linkage equations:

The single-phase magnetic linkage of FSPMSM comprises armature reaction magnetic linkage and permanent magnet flux linkage two parts, is:

ψ _p＝ψ _mp+L _pi _p(8)

Wherein, p represents motor A, B and C phase, i _pfor p phase winding electric current, L _pfor p phase winding self-induction, ψ _pfor motor p phase magnetic linkage, ψ _mpfor motor p phase permanent magnet flux linkage.

Voltage equation:

$\begin{array}{c}{u}_p=R_p{i}_p+\frac{d}{\mathrm{dt}}(L_p{i}_p+{\mathrm{\&psi;}}_{\mathrm{mp}})\\ =R_p{i}_p+L_p\frac{{\mathrm{di}}_p}{\mathrm{dt}}+i_p\frac{{\mathrm{dL}}_p}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r+\frac{d{\mathrm{\&psi;}}_{\mathrm{mp}}}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r\end{array}---\left(9\right)$

Wherein, R _pfor p phase winding resistance.

Torque equation:

FSPMSM exports electromagnetic torque and is made up of reluctance torque and permanent-magnet torque two parts, and wherein reluctance torque is by changing inductance and electric current acting in conjunction generation, and permanent-magnet torque is produced by the interaction of permanent magnet flux linkage and armature supply, and associated expression is:

$T_{\mathrm{ep}}=\frac{1}{2}{i}_p^2\frac{\&PartialD;L_p}{\&PartialD;{\mathrm{\&theta;}}_r}+i_p\frac{\&PartialD;{\mathrm{\&psi;}}_{\mathrm{pm},p}}{\&PartialD;{\mathrm{\&theta;}}_r}=T_{\mathrm{rp}}+T_{\mathrm{mp}}---\left(10\right)$

In above formula, for reluctance torque component, for permanent-magnet torque component.

The equation of motion:

$T_e=T_L+\mathrm{F\&omega;}+J\frac{\mathrm{d\&omega;}}{\mathrm{dt}}---\left(11\right)$

In above formula, T _efor motor exports electromagnetic torque, T _lfor load torque, J is system moment of inertia, and F is system friction coefficient, and ω is rotor mechanical angular speed.

According to formula (10), the total output electromagnetic torque of motor is:

T _e＝T _ea+T _eb+T _ec(12)

Model Predictive Control is a kind of control algolithm based on concrete things Mathematical Modeling, the object that the historical information of Main Basis forecasting object and wanting reaches, and dopes the development trend of key message.In the specific implementation process of PREDICTIVE CONTROL, model accuracy will largely determine the accuracy predicted.Same PREDICTIVE CONTROL can utilize different model tormulations, different optimal way, and different feedback strategies forms different predictive control algorithms.Therefore, Model Predictive Control has good adaptability to complication system.

As shown in Figure 2, the method for controlling torque of the switch flux-linkage permagnetic synchronous motor based on model prediction of the embodiment of the present invention comprises the steps:

(1) the switching tube state of motor inverter is combined, obtain eight groups of inverter switching device vector signals.

(2) at current time k, respectively under each group inverter switching device vector signal, the p phase winding voltage of switch flux-linkage permagnetic synchronous motor is gathered p phase winding electric current with rotor electrical angular velocity omega _r, the p phase winding electric current of prediction subsequent time k+1 for:

$i_p^{k+1}=i_p^k+\frac{1}{L_p}(u_p^k-R_p{i}_p^k-i_p^k\frac{d{L}_p}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r-\frac{d{\mathrm{\&psi;}}_{\mathrm{mp}}}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r)*T_s$

Wherein, L _pfor p phase winding self-induction, R _pfor p phase winding resistance, θ _rfor motor rotor position angle, ψ _mpfor motor p phase permanent magnet flux linkage, T _sfor the sampling period.

Particularly, be Accurate Prediction FSPMSM winding current value at a time, obtain current change quantity by formula (9) as follows:

$\frac{{\mathrm{di}}_p}{\mathrm{dt}}=(u_p-R_p{i}_p-i_p\frac{{\mathrm{dL}}_p}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r-\frac{d{\mathrm{\&psi;}}_{\mathrm{mp}}}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r)/L_p---\left(13\right)$

The p phase winding electric current being obtained next moment k+1 by formula (13) is:

$i_p^{k+1}=i_p^k+\frac{1}{L_p}(u_p^k-R_p{i}_p^k-i_p^k\frac{d{L}_p}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r-\frac{d{\mathrm{\&psi;}}_{\mathrm{mp}}}{d{\mathrm{\&theta;}}_r}{\mathrm{\&omega;}}_r)*T_s---\left(14\right)$

(3) respectively under each group inverter switching device vector signal, according to the p phase winding electric current of subsequent time k+1, in conjunction with Stator and Rotor Windings principle of coordinate transformation, the d axle of subsequent time k+1 and the current forecasting value of q axle is obtained with be respectively:

$\left[\begin{array}{c}{i}_d^{k+1}\\ i_q^{k+1}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\cos {\mathrm{\&theta;}}_e& \cos ({\mathrm{\&theta;}}_e-2\mathrm{\&pi;}/3)& \cos ({\mathrm{\&theta;}}_e+2\mathrm{\&pi;}/3)\\ \sin {\mathrm{\&theta;}}_e& \sin ({\mathrm{\&theta;}}_e-2\mathrm{\&pi;}/3)& \sin ({\mathrm{\&theta;}}_e+2\mathrm{\&pi;}/3)\end{array}\right]\&times;\left[\begin{array}{c}{i}_A^{k+1}\\ i_B^{k+1}\\ i_C^{k+1}\end{array}\right]---\left(15\right)$

Wherein, θ _efor motor in synchrony electrical degree, with be respectively A, B and C phase winding electric current of subsequent time k+1.

(4) respectively under each group inverter switching device vector signal, by p phase winding electric current and the dq shaft current predicted value of subsequent time k+1, the motor torque of prediction subsequent time k+1 $T_e^{k+1}=T_{\mathrm{eA}}^{k+1}+T_{\mathrm{eB}}^{k+1}+T_{\mathrm{eC}}^{k+1}$ With motor magnetic linkage ${\mathrm{\&psi;}}_s^{k+1}=(L_d{i}_d^{k+1}+{\mathrm{\&psi;}}_m)+j{L}_q{i}_q^{k+1},$ Wherein, with be respectively the A phase of subsequent time k+1, B phase and C phase motor torque, the p phase motor torque of subsequent time k+1 l _dand L _qbe respectively motor d axle and q axle self-induction, ψ _mfor permanent magnet flux linkage amplitude.

(5) respectively under each group inverter switching device vector signal, assess the cost function $G=|T_e^{*}-T_e^{k+1}|+k_1\left|\right|{\mathrm{\&psi;}}_s^{*}|-|{\mathrm{\&psi;}}_s^{k+1}\left|\right|+A\left(\right|T_e^{*}-T_e^{k+N}|+k_1|\left|{\mathrm{\&psi;}}_s^{*}\right|-\left|{\mathrm{\&psi;}}_s^{k+N}\right|\left|\right),$ Obtain cost function minimum time inverter switching device vector signal.Wherein, with be respectively the given reference value of motor torque and motor magnetic linkage, k ₁for the ratio of nominal torque and specified magnetic linkage, A is the regulating error coefficient of N state motor torque and motor magnetic linkage, and this coefficient can carry out correction adjustment according to control precision. with being respectively the motor torque in K+N moment and the predicted value of motor magnetic linkage, is namely the predicted value that benchmark infers the n-hour with current prediction error, and object is the control precision in order to regulate most current cost function.N is positive integer, and the numerical value for N is selected, and Main Basis motor is for the demand of control precision.

Obtained by linear resolution with expression formula be:

$T_e^{k+N}=T_e^k+(N-1)(T_e^{k+1}-T_e^K)---\left(16\right)$

$\left|{\mathrm{\&psi;}}_s^{k+N}\right|=\left|\right|{\mathrm{\&psi;}}_s^k|+(N-1)|\left|{\mathrm{\&psi;}}_s^{k+1}\right|-\left|{\mathrm{\&psi;}}_s^k\right|\left|\right|---\left(17\right)$

Wherein, with be respectively motor torque and the motor magnetic linkage of current time k.

The size of motor output torque undulate quantity, can reflect the operation characteristic of motor intuitively, and directly determines the application scenario (as servo system requires that torque fluctuations is very little) of motor.Therefore, the accurate control of motor output torque is just seemed particularly important.The main purpose of model prediction direct torque (ModelBasedPredictiveTorqueControl, MPTC) algorithm is exactly reduce motor output torque pulsating quantity to greatest extent.Have employed cost function (CostFunction) in the present invention, real-time assessment is carried out to each switching vector selector in each switch periods.The effect of cost function is exactly while evaluation prediction torque and magnetic linkage and torque reference and magnetic linkage error, selects optimum switching vector selector (best performance), guarantee the pulsating torque of FSPMSM and pulsation magnetic linkage minimum, and effectively reduce inverter switching device loss.According to different work and application scenario, cost function can do corresponding change, and it has good flexibility, can nonlinear restriction be joined in mathematical modeling preferably.

(6) defining the effective acting time of voltage vector and the ratio (duty ratio) in sampling period in current sample period is ramp, 0≤ramp≤1, be equivalent to the maximum changed in the range of linearity of motor torque and motor magnetic linkage in current sample period, wherein, C _tand C _ψtorque adjustment factor and magnetic linkage adjustment factor respectively.As m≤ramp, inverter switching device is failure to actuate, and exports Zero voltage vector; As m>ramp, inverter switching device vector signal when cost function is minimum is as the drive singal of inverter switching device, and the break-make of real-time control inverter switching tube, completes the direct torque to switch flux-linkage permagnetic synchronous motor.

C _tand C _ψfor realizing the balance between the dynamic response of modulation strategy and steady-state behaviour, obtaining mainly through experiment or emulation, namely by analysis design mothod or simulation result, constantly changing C _tand C _ψvalue, to obtain best experiment or simulation result.When m is very little, do not need inverter switching device action, only when m exceedes certain value, inverter switching device is just devoted oneself to work, and thus effectively can reduce the switching frequency of inverter.

As shown in Figure 3, the moment controlling system of switch flux-linkage permagnetic synchronous motor mainly comprises motor body model (FSPMSM), current forecasting module, pi regulator, switch flux-linkage permagnetic synchronous motor model, cost function minimization module (CostFunctionMinimization) and space vector modulation module.Motor body model is mainly according to the simulation model that motor mathematical model is built, and object is the research in order to simplify motor control strategy, thus shortens research cycle.Current forecasting module, with the current of electric of sampling and rotor speed, in conjunction with electric moter voltage equation, dopes the current value of motor in the next moment, for basis is carried out in the prediction of motor torque and motor magnetic linkage.Pi regulator, by comparing the size of reference rotation velocity and actual measurement rotating speed, considers the actual motion characteristic of motor according to the change of increment and micro component, obtains motor torque reference.The cost function minimization module collection current value of reference current value and prediction, for the purpose of cost function minimization, draws the switching signal required for device for power switching module.Under the state that space vector modulation module finds optimum vector signal at cost function, optimize the action time of switching vector selector further, reduce inverter switching frequency.

Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1., based on a method for controlling torque for the switch flux-linkage permagnetic synchronous motor of model prediction, it is characterized in that, comprise the steps:

(1) the switching tube state of motor inverter is combined, obtain eight groups of inverter switching device vector signals;

(2) at current time k, respectively under each group inverter switching device vector signal, the p phase winding voltage of switch flux-linkage permagnetic synchronous motor is gathered p phase winding electric current with rotor velocity ω _r, the p phase winding electric current of prediction subsequent time k+1 wherein, p represents motor A, B and C phase;

(3) respectively under each group inverter switching device vector signal, according to the p phase winding electric current of subsequent time k+1 in conjunction with Stator and Rotor Windings principle of coordinate transformation, obtain the d axle of subsequent time k+1 and the current forecasting value i of q axle _d ^k+1and i _q ^k+1;

(4) respectively under each group inverter switching device vector signal, by the p phase winding electric current of subsequent time k+1 d shaft current predicted value i _d ^k+1with q shaft current predicted value i _q ^k+1, the motor torque of prediction subsequent time k+1 with motor magnetic linkage

(5) respectively under each group inverter switching device vector signal, assess the cost function $G=\left|T_e^{*}-T_e^{k+1}\right|+k_1\left|\left|{\mathrm{\&psi;}}_s^{*}\right|-\left|{\mathrm{\&psi;}}_s^{k+1}\right|\right|+A\left(\right|T_e^{*}-T_e^{k+N}|+k_1|\left|{\mathrm{\&psi;}}_s^{*}\right|-\left|{\mathrm{\&psi;}}_s^{k+N}\right|\left|\right),$ Obtain cost function minimum time inverter switching device vector signal, wherein, with be respectively the reference value of motor torque and motor magnetic linkage, k ₁for the ratio of nominal torque and specified magnetic linkage, with be respectively the motor torque in k+N moment and the predicted value of motor magnetic linkage, N is positive integer, and A is the regulating error coefficient of N state motor torque and motor magnetic linkage;

(6) define wherein, C _tand C _ψtorque adjustment factor and magnetic linkage adjustment factor respectively, according to the value of m, control the effective acting time of inverter switching device vector signal when cost function is minimum in the single sampling period, to reduce the switching frequency of inverter, complete the direct torque to switch flux-linkage permagnetic synchronous motor.

2. the method for controlling torque of switch flux-linkage permagnetic synchronous motor as claimed in claim 1, it is characterized in that, the specific implementation of described step (6) is: in definition current sample period, the effective acting time of voltage vector and the ratio in sampling period are ramp, wherein, 0≤ramp≤1; As m≤ramp, inverter switching device pipe is failure to actuate, and exports Zero voltage vector; As m>ramp, inverter switching device vector signal when cost function is minimum is as the drive singal of inverter switching device pipe, and the break-make of real-time control inverter switching tube, completes the direct torque to switch flux-linkage permagnetic synchronous motor.

3. the method for controlling torque of switch flux-linkage permagnetic synchronous motor as claimed in claim 1 or 2, is characterized in that, in described step (2), and the p phase winding electric current of subsequent time k+1 for:

$i_p^{k+1}=i_p^k+\frac{1}{L_p}(u_p^k-R_p{i}_p^k-i_p^k\frac{{\mathrm{dL}}_p}{{\mathrm{d\&theta;}}_r}{\mathrm{\&omega;}}_r-\frac{{\mathrm{d\&psi;}}_{mp}}{{\mathrm{d\&theta;}}_r}{\mathrm{\&omega;}}_r)*T_s,$

Wherein, L _pfor p phase winding self-induction, R _pfor p phase winding resistance, θ _rfor motor rotor position angle, ψ _mpfor motor p phase permanent magnet flux linkage, T _sfor switch periods.

4. the method for controlling torque of switch flux-linkage permagnetic synchronous motor as claimed in claim 3, is characterized in that, in described step (3), and the d axle of subsequent time k+1 and the current forecasting value i of q axle _d ^k+1and i _q ^k+1be respectively:

$\left[\begin{array}{c}{i}_d^{k+1}\\ i_q^{k+1}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}{\mathrm{cos\&theta;}}_e& cos({\mathrm{\&theta;}}_e-2\mathrm{\&pi;}/3)& cos({\mathrm{\&theta;}}_e+2\mathrm{\&pi;}/3)\\ {\mathrm{sin\&theta;}}_e& sin({\mathrm{\&theta;}}_e-2\mathrm{\&pi;}/3)& sin({\mathrm{\&theta;}}_e+2\mathrm{\&pi;}/3)\end{array}\right]\&times;\left[\begin{array}{c}{i}_A^{k+1}\\ i_B^{k+1}\\ i_C^{k+1}\end{array}\right],$

Wherein, θ _efor motor in synchrony electrical degree, with be respectively the A phase of subsequent time k+1, B phase and C phase winding electric current.

5. the method for controlling torque of switch flux-linkage permagnetic synchronous motor as claimed in claim 1 or 2, is characterized in that, in described step (4), and the motor torque of subsequent time k+1 the motor magnetic linkage of subsequent time k+1 ${\mathrm{\&psi;}}_s^{k+1}=(L_d{i}_d^{k+1}+{\mathrm{\&psi;}}_m)+{\mathrm{jL}}_q{i}_q^{k+1},$ Wherein, with be respectively the A phase of subsequent time k+1, B phase and C phase motor torque, the p phase motor torque of subsequent time k+1 l _dand L _qbe respectively motor d axle and q axle self-induction, ψ _mfor permanent magnet flux linkage amplitude, L _pfor p phase winding self-induction, θ _rfor motor rotor position angle, ψ _mpfor motor p phase permanent magnet flux linkage.

6. the method for controlling torque of switch flux-linkage permagnetic synchronous motor as claimed in claim 1 or 2, is characterized in that, in described step (5), with expression formula be respectively:

$T_e^{k+N}=T_e^k+(N-1)(T_e^{k+1}-T_e^K),$

$\left|{\mathrm{\&psi;}}_s^{k+N}\right|=\left|\right|{\mathrm{\&psi;}}_s^k|+(N-1)|\left|{\mathrm{\&psi;}}_s^{k+1}\right|-\left|{\mathrm{\&psi;}}_s^k\right|\left|\right|,$

Wherein, with be respectively motor torque and the motor magnetic linkage of current time k.