CN103746624B - Based on the current control method of the bisalient-pole permanent-magnet synchronous machine of model prediction - Google Patents

Abstract

The invention discloses the current control method of a kind of bisalient-pole permanent-magnet synchronous machine (DSPM), comprise the steps: to obtain eight groups of inverter switching device vector signals; At current time k, under each group inverter switching device vector signal, the p phase stator current of prediction subsequent time k+1 wherein, p represents motor A, B and C phase; Under each group inverter switching device vector signal, according to obtain the current forecasting value of d axle and q axle; Under each group inverter switching device vector signal, calculate the d axle predicted current error of subsequent time k+1 with q axle predicted current error according to with choose torque ripple and magnetic linkage fluctuation total amount minimum time switching vector selector signal as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube.The method is by the accurate control to DSPM motor output current, and accurate control inverter switching vector selector change, makes motor torque fluctuate and magnetic linkage fluctuates minimum, requires low, fast response time to electrode parameter.

Description

Based on the current control method of the bisalient-pole permanent-magnet synchronous machine of model prediction

Technical field

The invention belongs to bisalient-pole permanent-magnet synchronous machine technical field, more specifically, relate to a kind of current control method of the bisalient-pole permanent-magnet synchronous machine based on model prediction.

Background technology

Bisalient-pole permanent-magnet synchronous machine (DoublySalientPermanentMagnetSynchronousMachine, DSPM) first basic structure proposed in the 1950's by Rauch and Johnson, due to the restriction by power electronics and electric machines control technology at that time, fail in the field of businessly to cause concern.Early 1990s, professor T.A.Lipo of Wisconsin-Madison university of the U.S. has carried out comprehensive further investigation to the new structure of DSPM and electromagnetic model etc., correlation theory and experimental study show, DSPM has very strong mechanical robustness and higher torque density, thus the research interest (R.F.SchiferlandT.A.Lipo of international counterparts is caused gradually, " Powercapabilityofsalientpolepermanentmagnetsynchronousmo torsinvariablespeeddriveapplications, " IEEETransactionsonIndustryApplications, vol.26, no.1, pp.115-123, Jan./Feb.1990.).

DSPM motor structurally remains most features of switched reluctance machines, and namely permanent magnet is arranged on stator, namely without permanent magnet also brushless on rotor, have structure simple, moment of inertia is little, and dynamic response is fast, power density is high, controls flexibly, efficiency advantages of higher.The current research to DSPM mainly concentrates on the optimal design of electromechanics structure and electromagnetic property.Stators and rotators due to DSPM is double-salient-pole structure, and the magnetic circuit of motor has asymmetry, and the electromagnetism local existed to a certain degree is saturated, causes the torque of DSPM to there is torque fluctuations in various degree, and strengthens with the increase of electric current and power grade.Merely improve electric machine structure and carry out Electromagnetic Optimum Design, the torque fluctuations of DSPM can not be reduced well and improve driveability, also there is length research cycle, high in cost of production shortcoming simultaneously.

Advanced control strategy can suppress the torque fluctuations of DSPM and significantly improve motor driving force, opposing body's structural design and electromagnetic optimize effectively, and it has short, the advantage such as cost is low research cycle, effectively can expand the range of application of DSPM.But the current control about DSPM is studied, focusing mostly on controls at switch OFF angle, (the horse Chang Mounts such as control cut by electric current list, cycle. the novel current ratio research of opening hold-off angle control strategy of doubly salient permanent magnet motor. Proceedings of the CSEE, 2009,29 (9): 67-73.).The dynamic responding speed of such control strategy is slow, requires higher to the parameter of electric machine simultaneously, in control procedure bad determine switch off current time and angle etc., had a strong impact on the driving force of DSPM.In addition, in practical application, due to the impact such as temperature rise and frequency, the parameters such as the inductance of DSPM and resistance will change a lot, in addition various peripheral signal interference, actual in selecting current-off time and angle, there will be comparatively big error, cause the torque of DSPM to worsen further, and then strengthen the transducer drive loss of DSPM.

Therefore, research there is autonomous regulating power, to the parameter of electric machine require low, the Novel Control of fast response time, for DSPM and drive system meaning very great.

Summary of the invention

For above defect or the Improvement requirement of prior art, the invention provides a kind of current control method of the bisalient-pole permanent-magnet synchronous machine based on model prediction, namely by the accurate control to DSPM motor output current, accurate control inverter switching vector selector change, motor torque fluctuation and magnetic linkage is made to fluctuate minimum, the method requires low to electrode parameter, fast response time.

For achieving the above object, the invention provides a kind of current control method of the bisalient-pole permanent-magnet synchronous machine based on model prediction, it is characterized in that, comprise the steps: that (1) switching tube state to motor inverter combines, 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 stator voltage of bisalient-pole permanent-magnet synchronous machine is gathered p phase stator current with rotor velocity ω _r, the p phase stator 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 stator current of subsequent time k+1 in conjunction with Stator and Rotor Windings principle of coordinate transformation, obtain the current forecasting value i of d axle and q axle _d ^k+1and i _q ^k+1; (4) respectively under each group inverter switching device vector signal, the d axle predicted current error of subsequent time k+1 is calculated with q axle predicted current error wherein, for d axle reference current, for q axle reference current; (5) according to the d axle predicted current error of subsequent time k+1 with q axle predicted current error real-time assessment is carried out to each switching vector selector in each switch periods, choose torque ripple and magnetic linkage fluctuation total amount minimum time inverter switching device vector signal, it can be used as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube, completes the Current Control to bisalient-pole permanent-magnet synchronous machine.

Preferably, in described step (2), the p phase stator current of subsequent time k+1 $i_p^{k+1}=i_p^k+$ $\frac{1}{L_p}(u_{\mathrm{pn}}-R_p{i}_p^k-i_p^k\frac{{\mathrm{dL}}_p}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r-\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r)*T_s,$ Wherein, L _pfor motor p phase stator self inductance, u _pnbe the motor p phase stator voltage that n-th group of inverter switching device vector signal is corresponding, n=1 ..., 8, R _pfor p phase stator resistance, θ _rfor motor rotor position angle, ψ _pmfor motor p phase permanent magnet flux linkage, T _sfor switch periods.

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

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

Wherein, i _d ^k+1and i _q ^k+1be respectively the current forecasting value of d axle and q axle, θ _efor motor in synchrony electrical degree, i _a ^k+1, i _b ^k+1and i _c ^k+1be respectively the A phase of subsequent time k+1, B phase and C phase stator current.

Preferably, in described step (4), obtained by pi regulator by motor reference rotation velocity and output speed.

Preferably, the specific implementation of described step (5) is:

Constructions cost function wherein, k ₁for weight coefficient, choose cost function G minimum time inverter switching device vector signal, it can be used as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube, completes the Current Control to bisalient-pole permanent-magnet synchronous machine.

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

1, the accurate control to DSPM motor output current can be realized.With motor equivalent voltage model and equivalent magnetic chain model for theoretical foundation, under effectively doping eight kinds of inverter switching states, the value of motor output current under three-phase (A, B, C phase) coordinate system of subsequent time, in conjunction with rotor stator principle of coordinate transformation, coordinate transform (3 phase/2 phase) is carried out to the current forecasting value under three phase coordinate systems, derives the current forecasting value under dq axis coordinate system.

2, accurately control inverter switching vector selector change, makes motor torque fluctuate and magnetic linkage fluctuates minimum, requires low, fast response time to electrode parameter.Introduce cost function (CostFunction) theoretical, and the cost function set up based on current error, based on this cost function, in each switch periods, calculated by on-line optimization, select cost function minimum time corresponding switching vector selector signal, real-time control inverter work, regulate DSPM that its torque fluctuations is reduced, associated drives performance is improved.

Accompanying drawing explanation

Fig. 1 is the current control method flow chart of the bisalient-pole permanent-magnet synchronous machine of the embodiment of the present invention;

Fig. 2 is the current control system structural representation of bisalient-pole permanent-magnet synchronous machine.

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 doubly salient permanent magnet motor is as follows:

Flux linkage equations:

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

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 _abfor A phase and B phase mutual inductance (other simileys implications duplicate), 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 DSPM is further:

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

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

The torque equation of tradition permagnetic synchronous motor is:

$T_e=\frac{1}{2}{\left[I\right]}^T\left(\frac{\∂}{\∂{\mathrm{\θ}}_r}\right[L\left]\right)\left[I\right]+\left(\frac{\∂}{\∂{\mathrm{\θ}}_r}{\left[{\mathrm{\ψ}}_{\mathrm{pm}}\right]}^T\right)\left[I\right]---\left(3\right)$

Traditional permagnetic synchronous motor inductance parameters is fixed numbers, not with rotor position angle θ _rchange and change.Because the particularity of DSPM electric machine structure and rotor are all double-salient-pole structures, the inductance of DSPM is with rotor position angle θ _rchange and change, be the function of rotor-position, therefore formula (3) can not directly in order to solve the electromagnetic torque of DSPM.

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

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

Flux linkage equations:

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

Write as matrix form

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

Wherein, L _d, L _qand L _dqrepresent the mutual inductance of the motor d axle self-induction after dq conversion, q axle self-induction and d axle and q between centers respectively, i _dand i _qfor transforming to the electric current of d axle and q axle.

Voltage equation:

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

In above formula, u _dand u _qfor transforming to the electric moter voltage of d axle and q axle, ω _rfor rotor velocity.

Torque equation:

$\begin{array}{c}{T}_e=\frac{1}{2}{\left[I\right]}^T\left(\frac{\∂}{\∂{\mathrm{\θ}}_r}\right[L\left]\right)\left[I\right]+\left(\frac{\∂}{\∂{\mathrm{\θ}}_r}{{[\mathrm{\ψ}}_{\mathrm{pm}}]}^T\right)\left[I\right]\\ =\frac{3}{2}{P}_r{\mathrm{\ψ}}_m{I}_q-\frac{3}{8}{P}_r(2M_m+L_m)[(I_d^2-I_q^2)\sin \left(3{\mathrm{\θ}}_e\right)\\ +2I_d{I}_q\cos \left(3{\mathrm{\θ}}_e\right)]+\frac{3}{2}{P}_r(L_m-M_m)I_0{I}_q\\ =\frac{3}{2}{P}_r{\mathrm{\ψ}}_m{I}_q+\frac{3}{4}{P}_r[L_{\mathrm{dq}}(I_d^2-I_q^2)-(L_d-L_q)I_d{I}_q]+\frac{3}{2}{P}_r{L}_{d0}{I}_0{I}_q\end{array}---\left(7\right)$

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 DSPM equivalent equation:

Flux linkage equations:

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

ψ _p＝ψ _pm+L _pi _p(8)

Wherein, p represents motor A, B and C phase, i _pfor motor p phase stator current, L _pfor motor p phase stator self inductance, ψ _pfor motor p phase magnetic linkage, ψ _pmfor motor p phase permanent magnet flux linkage.

Voltage equation:

$\begin{array}{c}{u}_p=R_p{i}_p+e=R_p{i}_p+\frac{d{\mathrm{\ψ}}_p}{\mathrm{dt}}=\\ R_p{i}_p+\frac{d(L_p{i}_p+{\mathrm{\ψ}}_m)}{\mathrm{dt}}=R_p{i}_p+L_p\frac{{\mathrm{di}}_p}{\mathrm{dt}}+(i_p\frac{{\mathrm{dL}}_p}{d{\mathrm{\θ}}_r}+\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}){\mathrm{\ω}}_r\end{array}---\left(9\right)$

Wherein, R _pfor p phase stator resistance.

Torque equation:

DSPM motor 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:

$T_{\mathrm{ep}}=\frac{1}{2}{i}_p^2\frac{\∂L_p}{\∂{\mathrm{\θ}}_r}+i_p\frac{\∂{\mathrm{\ψ}}_{\mathrm{pm}}}{\∂{\mathrm{\θ}}_r}=T_{\mathrm{rp}}+T_{\mathrm{mp}}---\left(10\right)$

In above formula, for reluctance torque component, for permanent-magnet torque component.From formula (10), reluctance torque component T _rpsize and the sense of current have nothing to do, and relevant with inductance rate of change; Permanent-magnet torque component T _mpsize both relevant with the sense of current, be also subject to permanent magnet flux linkage rate of change impact.Owing to there being the existence of permanent magnet, in DSPM motor, magnetic circuit reluctance is comparatively large, and stator inductance is relatively little.Therefore, permanent-magnet torque T _mpmuch larger than reluctance torque T _rp, be the main component of electromagnetic torque.

The equation of motion:

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

In above formula, T _efor the electromagnetic torque that motor exports, 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 (11), the total output electromagnetic torque of motor is

T _e＝T _ea+T _eb+T _ec(12)

PREDICTIVE CONTROL is a kind of System design based on model algorithm, and it can according to the historical information of object and following input, and the future of real-time estimate object exports.In the specific implementation process of PREDICTIVE CONTROL, the version of the function ratio model of model is even more important.PREDICTIVE CONTROL can utilize different model tormulations, different optimal way, and different feedback strategies forms different predictive control algorithms, and it has good adaptability to complication system.

As shown in Figure 1, the current control method of the bisalient-pole permanent-magnet synchronous machine 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 stator voltage of bisalient-pole permanent-magnet synchronous machine is gathered p phase stator current with rotor velocity ω _r, the p phase stator current of prediction subsequent time k+1 $i_p^{k+1}=i_p^k+\frac{1}{L_p}(u_{\mathrm{pn}}-R_p{i}_p^k-i_p^k\frac{{\mathrm{dL}}_p}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r-\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r)*T_s,$ Wherein, L _pfor motor p phase stator self inductance, u _pnbe the motor p phase stator voltage that n-th group of inverter switching device vector signal is corresponding, n=1 ..., 8, R _pfor p phase stator resistance, θ _rfor motor rotor position angle, ψ _pmfor motor p phase permanent magnet flux linkage, T _sfor switch periods.

Particularly, be Accurate Prediction DSPM stator current value at a time, the stator voltage that can be obtained under 8 kinds of inverter switching states by formula (9) is:

$u_{\mathrm{pn}}=R_p{i}_p+L_p\frac{{\mathrm{di}}_p}{\mathrm{dt}}+i_p\frac{{\mathrm{dL}}_p}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r+\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r---\left(13\right)$

The inductive drop pressure drop caused by curent change, resistance drop and electrical degree and anti-magnetic linkage amplitude can be drawn by following formula:

$u_{\mathrm{Lp}}=L_p\frac{{\mathrm{di}}_p}{\mathrm{dt}}=u_{\mathrm{pn}}-R_p{i}_p-i_p\frac{{\mathrm{dL}}_p}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r-\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r---\left(14\right)$

Based on p phase stator voltage u _p, often kind of inverter switching states and p phase stator current i _p, obtain the current differential amount under often kind of inverter switching states:

$\frac{{\mathrm{di}}_p}{\mathrm{dt}}=(u_{\mathrm{pn}}-R_p{i}_p-i_p\frac{{\mathrm{dL}}_p}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r-\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r)/L_p---\left(15\right)$

The calculating of the error desired value of every phase current mainly relies on inverter switching device vector.Based on switch periods T _s, obtain the knots modification of every phase current:

$\mathrm{\Δ}{i}_p^{k+1}=\frac{1}{L_p}(u_{\mathrm{pn}}-R_p{i}_p^k-i_p^k\frac{d{L}_p}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r-\frac{d{\mathrm{\ψ}}_{\mathrm{pm}}}{d{\mathrm{\θ}}_r}{\mathrm{\ω}}_r)*T_s---\left(16\right)$

According to the p phase stator voltage of current sample time k p phase stator current the p phase stator current of prediction subsequent time k+1

$i_p^{k+1}=i_p^k+\mathrm{\Δ}{i}_p^{k+1}---\left(17\right)$

(3) respectively under each group inverter switching device vector signal, according to the p phase stator current of subsequent time k+1 in conjunction with Stator and Rotor Windings principle of coordinate transformation, obtain the current forecasting value under dq axle:

$\left[\begin{array}{c}{i}_d^{k+1}\\ i_q^{k+1}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\cos {\mathrm{\θ}}_e& \cos ({\mathrm{\θ}}_e-2\mathrm{\π}/3)& \cos ({\mathrm{\θ}}_e+2\mathrm{\π}/3)\\ \sin {\mathrm{\θ}}_e& \sin ({\mathrm{\θ}}_e-2\mathrm{\π}/3)& \sin ({\mathrm{\θ}}_e+2\mathrm{\π}/3)\end{array}\right]\×\left[\begin{array}{c}{i}_A^{k+1}\\ i_B^{k+1}\\ i_C^{k+1}\end{array}\right]---\left(18\right)$

Wherein, i _d ^k+1and i _q ^k+1be respectively the current forecasting value of d axle and q axle, θ _efor motor electrical degree, i _a ^k+1, i _b ^k+1and i _c ^k+1be respectively the A phase of subsequent time k+1, B phase and C phase stator current.

(4) respectively under each group inverter switching device vector signal, the d axle predicted current error of subsequent time k+1 is calculated with q axle predicted current error wherein, for d axle reference current, for q axle reference current, obtained by pi regulator by motor reference rotation velocity and output speed.

Current error is defined as the difference between current actual current vector and reference current vector.Accurately controlling object to reach, should as far as possible current error be controlled minimum, therefore, in line computation and optimizing process, grasp current error principle and be necessary.Current error calculates primarily of dq shaft current amount.

The d shaft current error of current time k with q shaft current error be respectively:

$\left\{\begin{array}{c}{e}_d^k=i_d^{*}-i_d^k\\ e_q^k=i_q^{*}-i_q^k\end{array}\right.---\left(19\right)$

From current time k to the knots modification of subsequent time k+1, d shaft current with the knots modification of q shaft current be respectively:

$\left\{\begin{array}{c}\mathrm{\Δ}{i}_d^{k+1}=i_d^{k+1}-i_d^k\\ \mathrm{\Δ}{i}_q^{k+1}=i_q^{k+1}-i_q^k\end{array}\right.---\left(20\right)$

Obtain the d axle predicted current error of subsequent time k+1 with q axle predicted current error be respectively:

$\left\{\begin{array}{c}{e}_d^{k+1}=e_d^k-\mathrm{\Δ}{i}_d^{k+1}\\ e_q^{k+1}=e_q^k-\mathrm{\Δ}{i}_q^{k+1}\end{array}\right.---\left(21\right)$

From analyzing above, the PREDICTIVE CONTROL principle of DSPM is the concrete mathematical model based on motor, and time namely with different Mathematical Modeling simulated machine bodies, corresponding predictive control strategy will carry out relevant adjustment.The Mathematical Modeling of contrast DSPM and control strategy, can find out that motor mathematical model is important prerequisite and the basis of the enforcement of whole algorithm.

(5) according to the d axle predicted current error of subsequent time k+1 with q axle predicted current error real-time assessment is carried out to each switching vector selector in each switch periods, choose torque ripple and magnetic linkage fluctuation total amount minimum time inverter switching device vector signal, it can be used as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube, completes the Current Control to bisalient-pole permanent-magnet synchronous machine.

From formula (8) and formula (10), the electric current of the size that motor torque fluctuation and magnetic linkage fluctuate and motor is closely related, and namely the fluctuation of current of electric directly affects the control precision of motor.The cardinal principle of model prediction Current Control (ModelPredictiveCurrentControl, MPCC) strategy is exactly make the fluctuation of current of electric minimum.The embodiment of the present invention adopts cost function (CostFunction) to carry out real-time assessment to each switching vector selector in each switch periods.The effect of cost function is exactly while assessment current error, selects optimum switching vector selector (best performance), guarantee the torque ripple of DSPM and magnetic linkage fluctuation total amount minimum, and effectively reduce inverter switching device loss.According to different work and application scenario, cost function can be changed accordingly, and it has good flexibility, can nonlinear restriction be joined in mathematical modeling preferably.

The cost function of the present embodiment is specially:

$G=\left|e_d^{k+1}\right|+k_1\×\left|e_q^{k+1}\right|---\left(22\right)$

Wherein, k ₁for weight coefficient.This cost function only considers the predicted current error under dq axle with object reduces the minimum uncertain factor of impact evaluation current error.

Choose cost function G minimum time inverter switching device vector signal, it can be used as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube, completes the Current Control to bisalient-pole permanent-magnet synchronous machine.

As can be seen here, the embodiment of the present invention passes through current of electric and the inverter switching device vector of measurement, obtains the current forecasting value of subsequent time according to current forecasting model.Obtain dq shaft current predicted value further by coordinate transform, after carrying out current error assessment, select optimum inverter switching device vector through cost function.

As shown in Figure 2, the current control system of bisalient-pole permanent-magnet synchronous machine mainly comprises motor body model (DSPM), current forecasting module, three-phase voltage source inverter (device for power switching, 3L-VSI), PI adjustment module and cost function minimization module (CostFunctionMinimization), each module and other modules have strict on logical relation.Mathematical principle motor that is virtually reality like reality used exactly by motor body model, thus reaches the object simplifying research doubly salient permanent magnet motor control strategy.Current forecasting module is built according to formula (13) ~ (18) exactly, and Main Function dopes next moment motor output current exactly.PI module mainly obtains motor reference current by comparing motor reference rotation velocity with sampling rotating speed.Cost function (CostFunction) has gathered reference current and predicted current, is minimised as object with CostFunction, draws the switching signal required for device for power switching module, thus drive motors rotates according to the rotating speed of setting.

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 (5)

1. a current control method for bisalient-pole permanent-magnet synchronous machine, is characterized in that, 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 stator voltage of bisalient-pole permanent-magnet synchronous machine is gathered p phase stator current with rotor velocity ω _r, the p phase stator 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 stator current of subsequent time k+1 in conjunction with Stator and Rotor Windings principle of coordinate transformation, obtain the current forecasting value i of d axle and q axle _d ^k+1and i _q ^k+1;

(4) respectively under each group inverter switching device vector signal, the d axle predicted current error of subsequent time k+1 is calculated with q axle predicted current error wherein, for d axle reference current, for q axle reference current;

(5) according to the d axle predicted current error of subsequent time k+1 with q axle predicted current error real-time assessment is carried out to each switching vector selector in each switch periods, choose torque ripple and magnetic linkage fluctuation total amount minimum time inverter switching device vector signal, it can be used as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube, completes the Current Control to bisalient-pole permanent-magnet synchronous machine.

2. the current control method of bisalient-pole permanent-magnet synchronous machine as claimed in claim 1, is characterized in that, in described step (2), and the p phase stator current of subsequent time k+1 wherein, L _pfor motor p phase stator self inductance, u _pnbe the motor p phase stator voltage that n-th group of inverter switching device vector signal is corresponding, n=1 ..., 8, R _pfor p phase stator resistance, θ _rfor motor rotor position angle, ψ _pmfor motor p phase permanent magnet flux linkage, T _sfor switch periods.

3. the current control method of bisalient-pole permanent-magnet synchronous machine as claimed in claim 2, is characterized in that, in described step (3), and the current forecasting value i of d axle and q axle _d ^k+1and i _q ^k+1can be expressed as:

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

Wherein, i _d ^k+1and i _q ^k+1be respectively the current forecasting value of d axle and q axle, θ _efor motor in synchrony electrical degree, i _a ^k+1, i _b ^k+1and i _c ^k+1be respectively the A phase of subsequent time k+1, B phase and C phase stator current.

4. the current control method of bisalient-pole permanent-magnet synchronous machine as claimed any one in claims 1 to 3, is characterized in that, in described step (4), obtained by pi regulator by motor reference rotation velocity and output speed.

5. the current control method of bisalient-pole permanent-magnet synchronous machine as claimed any one in claims 1 to 3, it is characterized in that, the specific implementation of described step (5) is:

Constructions cost function wherein, k ₁for weight coefficient, choose cost function G minimum time inverter switching device vector signal, it can be used as the drive singal of inverter switching device, the break-make of real-time control inverter switching tube, completes the Current Control to bisalient-pole permanent-magnet synchronous machine.