CN103731082A - Stator flux linkage estimation method of permanent magnet synchronous motor based on direct torque control - Google Patents

Abstract

The invention discloses a closed loop flux linkage estimation method which is applied to a direct torque control system of a permanent magnet synchronous motor. Calculation is conducted through voltage signals and current signals measured in a real-time sampling mode according to a voltage method flux linkage calculation formula so that initial estimation flux linkage can be obtained, then, the initial estimation flux linkage and target control flux linkage are used as input quantity, a PI regulator is used for conducting dynamic state closed loop correction, and accordingly the target control flux linkage can be tracked ultimately. The given control flux linage controlled by direct torque is used as the amplitude of the target control flux linkage in a flux linkage estimator, the rotor position angle is obtained through a position sensor, and the angle information is dynamically compensated to be used as the angle information of the target control flux linkage. Through closed loop regulation to the voltage method flux linkage estimator, flux linkage calculation deviation caused by direct current bias and initial integration in an integration element can be effectively eliminated, the real flux linkage can be accurately estimated, and good rapidity and robustness are achieved in the actual direct torque control system.

Description

A kind of permanent-magnetic synchronous motor stator magnetic linkage method of estimation based on direct torque control

Technical field

The present invention relates to a kind of magnetic linkage method of estimation of permagnetic synchronous motor, relate in particular to a kind of permanent-magnetic synchronous motor stator magnetic linkage method of estimation based on direct torque control.

Background technology

In the middle of motor dynamics control field, Study on direct torque control technology, with its control performance fast and accurately, is more and more applied in the middle of permagnetic synchronous motor, asynchronous machine and some other New-type electric machine.In the middle of Direct Torque is dynamically controlled, two direct control objects are torque and magnetic linkage, the two is all to be calculated by the variable quantities such as voltage, electric current, positional information and the parameter of electric machine, because torque is to be drawn by magnetic linkage and other calculation of parameter, so be exactly in fact the accurate calculating to motor magnetic linkage to the computational problem of two control objects.

Flux linkage calculation method generally can be divided into potentiometer algorithm and galvanometer algorithm.Potentiometer algorithm is comparatively simple, and it is to utilize stator voltage equation, by integrator, calculates; Current method is to utilize rotor voltage equation, through conversion substitution, draws flux linkage calculation equation.Voltage method theoretical model is simple, but in the middle of practical application, but has some problems, the impact of the direct current biasing during as low speed in stator resistance variation, initial value for integral, sampled signal etc.Also existent defect of galvanometer algorithm, the dependence parameter of electric machine that current method is more, and in the middle of motor operation, along with the variation of temperature and speed, the parameter of electric machine also has certain variation, is subject in addition the impact of rotor time constant during high speed, while causing high speed current method flux linkage calculation not as voltage method accurate.According to the feature of voltage method and current method, can use the account form of low speed current method, High-speed Electric platen press, by filter, realize the conversion of the two, but this mode is comparatively complicated and be all can be in its working region with two kinds of methods, realizes accurate Calculation and be prerequisite.Numerous scholars have made many improving one's methods according to the feature of voltage method and current method, as add low pass filter method, high-pass and low-pass filter matching method, closed loop orthosis, Kalman filter method etc., these methods have all improved the accuracy that magnetic linkage is estimated to a certain extent, but also band is served problem, add filtered method and can eliminate initial integration error, decaying dc biasing, but can bring phase-amplitude biasing, high-pass and low-pass filter coordinates can make the magnetic linkage estimation effect that takes on a new look to a certain extent on the basis of low pass filter, but introduced more parameter, during closed loop orthosis stable state, there is good effect, but in the middle of actual direct Torque Control, in the time of dynamically, the meeting of direct torque control effect and flux linkage calculation effect influence each other, the result of double influence makes whole control system be easy to loss of stability, also can there is the poor problem of dynamic time effect fruit in the flux linkage calculation mode that adds filter, Kalman filter has been alleviated the shortcoming of current method to a certain extent, but cannot avoid the dependence to the parameter of electric machine in flux linkage calculation, this parameter of electric machine under different operating modes changes motor greatly still can there is the error of calculation greatly, add Kalman filter also to need the calculating of relative complex.

Summary of the invention

Goal of the invention: for above-mentioned prior art, a kind of permanent-magnetic synchronous motor stator magnetic linkage method of estimation based on direct torque control is proposed, cross the closed-loop adjustment to voltage method Flux estimator, effectively eliminate its integral element because of the flux linkage calculation deviation that direct current biasing, initial value for integral cause, accurately estimate true magnetic linkage.

Technical scheme: a kind of permanent-magnetic synchronous motor stator magnetic linkage method of estimation based on direct torque control, when initial control cycle calculates magnetic linkage, records the three-phase voltage U of permagnetic synchronous motor in real time _a, U _b, U _c, and three-phase current i _a, i _b, i _c, the described voltage and current under three-phase rotating coordinate system is transformed to the voltage u of α β coordinate system _α, u _β, current i _α, i _β; In control cycle of direct Torque Control according to formula (1) to described voltage u _α, u _βcarry out integral and calculating, obtain magnetic linkage according to a preliminary estimate

Wherein, R _sfor motor stator resistance;

By described magnetic linkage according to a preliminary estimate

with target control magnetic linkage reference value

by PI control algolithm, obtain DC offset voltage compensation rate V _α, V _β; Wherein, according to formula (2), obtain the integration item sum of PI control algolithm _α, sum _β:

Wherein, K _ifor integral coefficient; sum _α', sum ' _βfor the integration item that a control cycle in direct Torque Control obtains, sum _α', sum ' _βinitial value is 0; for target control magnetic linkage reference value:

Wherein, ψ ^*for the given control magnetic linkage of direct Torque Control, ψ ^*as target control magnetic linkage amplitude; θ is the stator magnet chain angle of target control magnetic linkage;

According to formula (3), obtain described DC offset voltage compensation rate V _α, V _β:

Wherein, K _pfor proportionality coefficient;

According to described DC offset voltage compensation rate V _α, V _β, according to formula (4), calculate the motor magnetic linkage that Flux estimator is estimated

When next control cycle, the motor magnetic linkage that utilizes a upper control cycle to estimate

replace magnetic linkage according to a preliminary estimate

substitution formula (2) is calculated, and forms closed-loop regulating system; When closed-loop regulator realizes target control magnetic linkage

while dynamically following the tracks of, the estimation magnetic linkage of described Flux estimator

be motor magnetic linkage accurately.

As preferred version of the present invention, utilize rotor-position sensor to draw the rotor position angle γ of motor under direct torque control, and described rotor position angle γ is carried out after closed-loop dynamic compensation, draw the stator magnet chain angle θ of described target control magnetic linkage; Described dynamic compensation calculates suc as formula shown in (5):

θ=γ+δ (5)

Wherein, γ is rotor position angle; δ is angle of torsion, and the offset angle of rotor position angle is equaled to described angle of torsion;

Described angle of torsion calculates suc as formula shown in (6):

Wherein, described in serving as reasons

the target control magnetic linkage stator magnet chain angle of utilizing arctan function to calculate;

for the estimation motor magnetic linkage calculating according to described formula (2)

utilize the stator magnet chain angle of the motor magnetic linkage that arctan function calculates;

In closed loop compensation process, offset is carried out adopting while periodically calculating to the method for accumulator accumulation calculating, shown in (7):

sum=sum+gel (7)

Wherein sum is offset angle accumulator, and its initial value is 0, gel is the offset angle of the rotor position angle calculating according to described formula (6); Accumulator is remembered the angle compensation value of this direct Torque Control control cycle, and in the calculating of the angle compensation in lower cycle of substitution, realizes the periodicity dynamic compensation of angle, and described periodic quantity is set to 0.3-3 motor electrical cycle.

Beneficial effect: compared with prior art, voltage, current signal that the present invention utilizes real-time sampling to measure, according to voltage method flux linkage calculation formula, calculate, draw magnetic linkage according to a preliminary estimate, then as input variable, utilize pi regulator to carry out dynamic closed loop rectification itself and target control magnetic linkage, make its final above target control magnetic linkage of following the tracks of.Wherein the given control magnetic linkage of direct torque control, as the target control magnetic linkage amplitude in Flux estimator, utilizes position transducer to draw rotor position angle, this angle information is carried out to dynamic compensation, as the angle information of target control magnetic linkage.By the closed-loop adjustment to voltage method Flux estimator, the present invention has eliminated the magnetic linkage direct current biasing in flux linkage calculation, integration initial value error problem, effectively improve the accuracy of flux linkage calculation, also can reduce to a certain extent the central sensitiveness to stator resistance of flux linkage calculation simultaneously, compared to adding filtering link flux linkage calculation method and there is no the closed loop flux linkage calculation method of angle compensation, algorithm of the present invention shows better accuracy, robustness in direct Torque Control.In actual direct Torque Control, the angle information accuracy of magnetic linkage is the key link of whole control system stability, so the angle information of target magnetic linkage is estimated will accomplish to stablize, continuously, accurately, because the basic angle information that has adopted rotor position angle to estimate as magnetic linkage in the present invention, so have good stability row, continuity, can effectively improve by angle compensation the accuracy that magnetic linkage is estimated.

Accompanying drawing explanation

Fig. 1 is magneto direct torque control block diagram;

Fig. 2 is to be flux linkage calculation entire block diagram;

Fig. 3 is to be magnetic linkage angle compensation theory diagram;

Fig. 4 is to be magnetic linkage angle compensation computing block diagram;

Fig. 5 is for adopting the inventive method to carry out the flux linkage calculation effect of angle compensation;

Fig. 6 is the flux linkage calculation effect when not carrying out angle compensation;

The situation of change of Fig. 7 angle compensation value

Embodiment

Below in conjunction with accompanying drawing, the present invention is done further and explained.

As shown in Figure 1, wherein, the parameter of permagnetic synchronous motor is the direct Torque Control block diagram of matlab emulation embodiment of the present invention: number of pole-pairs p=2, stator resistance R _s=2 Ω, d-axis inductance L _d=31.06mH, quadrature axis inductance L _q=80.69mH, permanent magnetism magnetic linkage

direct Torque Control adopts switch list vector control mode, determines the control parameter of using in control flow according to control system characteristic, and in the present embodiment, matlab simulation step length is set to 1 × 10 ^-5s, DC power supply voltage is set to 700V, K in Flux estimator _p=100, integral coefficient K _i=200, the angle compensation cycle is 0.018s, while carrying out angle compensation, pi regulator output violent change is [120,120], and control speed setting value is 1300r/min, load torque is 40Nm, and controlling flux linkage set value is 1.13Wb, contains in addition the direct current biasing of 3V in voltage sample.

The theory diagram of the Flux estimator entirety shown in Fig. 2, utilizes voltage method to calculate magnetic linkage, first needs to utilize sensor sample voltage, current signal, utilizes position transducer sampling to draw rotor position angle γ.When initial calculation magnetic linkage, record in real time the three-phase voltage U of permagnetic synchronous motor _a, U _b, U _c, and three-phase current i _a, i _b, i _c, the described voltage and current under three-phase rotating coordinate system is transformed to the voltage u of α β coordinate system _α, u _β, current i _α, i _β; Formula of Coordinate System Transformation is shown below:

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}1& 1/2& 1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right]$

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}1& 1/2& 1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

In control cycle of direct Torque Control, according to formula (1) to described voltage u _α, u _βcarry out integral and calculating, obtain magnetic linkage according to a preliminary estimate

Wherein, R _sfor motor stator resistance;

By described magnetic linkage according to a preliminary estimate with target control magnetic linkage reference value

by PI control algolithm, obtain DC offset voltage compensation rate V _α, V _β; By pi regulator, form a closed-loop regulating system, the integral and calculating initial value error that the sampling error existing in numerical control system and rotor position are brought is dynamically corrected.Wherein, the proportional integral link of PI controller is calculated according to formula (2), formula (3); Wherein, according to formula (2), obtain the integration item sum of PI control algolithm _α, sum _β:

Wherein, K _ifor integral coefficient; sum _α', sum ' _βfor the integration item that a control cycle in direct Torque Control obtains, sum _α', sum ' _βinitial value is 0;

for target control magnetic linkage reference value:

Wherein, ψ ^*for the given control magnetic linkage of direct Torque Control, ψ ^*as target control magnetic linkage amplitude; θ is the stator magnet chain angle of target control magnetic linkage;

According to formula (3), obtain described DC offset voltage compensation rate V _α, V _β:

Wherein, K _pfor proportionality coefficient;

According to described DC offset voltage compensation rate V _α, V _β, according to formula (4), calculate the motor magnetic linkage that Flux estimator is estimated

When closed-loop regulator realizes target control magnetic linkage

while dynamically following the tracks of, described DC offset voltage compensation rate V _α, V _βbe 0, described magnetic linkage according to a preliminary estimate

be motor magnetic linkage accurately

Wherein, the given control magnetic linkage ψ of direct Torque Control ^*as target control magnetic linkage amplitude, the set-point of magnetic linkage carrys out given magnetic linkage amplitude according to the principle most effective, loss is minimum in motor rated speed range of operation, when motor speed during higher than rated speed according to the given magnetic linkage amplitude of weak magnetic algorithm; Target control flux linkage set amplitude is shown below:

$\left\{\begin{array}{c}{\mathrm{\&psi;}}^{*}=f\left(P_l\right)\\ {\mathrm{\&psi;}}^{*}=f^{\&prime;}(\mathrm{Te},n)\\ {\mathrm{\&psi;}}^{*}<\frac{\mathrm{\&rho;}}{\mathrm{\&rho;}-1}{\mathrm{\&phi;}}_f\end{array}\right.$

Wherein, P _lfor the loss power of motor, ρ=quadrature axis inductance/d-axis inductance, i.e. motor salient pole rate, Te is motor electromagnetic torque, f (P _l) be the flux linkage calculation amplitude drawing according to loss minimum principle, φ _ffor permanent magnetism magnetic linkage.When motor operates in rated speed when above, target control magnetic linkage is set amplitude and is calculated according to weak magnetic algorithm f ' (Te, n), and two computing functions are relevant with motor self character and working control algorithm target.The motor not waiting for ac-dc axis inductance, changes a straightforward principle according to motor torque and angle of torsion and sets up Maximum Constraint.

Be illustrated in figure 3 the vector schematic diagram of angle compensation, the angle information of target control magnetic linkage utilizes position transducer to measure, because the location information signal of measuring not is flux linkage calculation angle information signal accurately, so need location information signal to carry out angle compensation, draw stator magnet chain angle θ.Utilize rotor-position sensor to draw the rotor position angle γ of motor under direct torque control, and described rotor position angle γ is carried out after closed-loop dynamic compensation, draw the stator magnet chain angle θ of described target control magnetic linkage; Described dynamic compensation calculates suc as formula shown in (5):

θ=γ+δ (5)

Wherein, γ is rotor position angle; δ is angle of torsion, and the offset angle of rotor position angle is equaled to described angle of torsion;

Described angle of torsion calculates suc as formula shown in (6):

Wherein,

described in serving as reasons

the target control magnetic linkage stator magnet chain angle of utilizing arctan function to calculate;

for the estimation motor magnetic linkage calculating according to described formula (2)

utilize the stator magnet chain angle of the motor magnetic linkage that arctan function calculates;

In Fig. 3 for stator magnetic linkage, this magnetic linkage comprises the magnetic linkage that stator current produces

with via permanent magnetism magnetic linkage after magnetic field modulation

as can be seen from Figure 3 the stator magnet chain angle that in α β coordinate system, stator magnetic linkage is decomposed to two reference axis is rotor position angle γ and angle of torsion δ sum.In conjunction with Fig. 3, can draw the torque equation of motor:

$T_{\mathrm{em}}=\frac{3p\left|{\mathrm{\&psi;}}_s\right|}{{4L}_d{L}_q}[2{\mathrm{\&psi;}}_f{L}_q\sin \mathrm{\&delta;}-|{\mathrm{\&psi;}}_s\left|(L_q-L_d)\sin 2\mathrm{\&delta;}\right]---\left(7\right)$

Wherein, T _emfor motor electromagnetic torque, δ is rotor magnetic linkage angle, i.e. angle of torsion, and p is stator winding number of pole-pairs, L _dfor the d-axis inductance of motor, L _qfor the quadrature axis inductance of motor, ψ _sfor stator magnetic linkage amplitude.By formula (7), can be found out, torque is a physical quantity relevant with angle of torsion, its physical relationship is determined according to motor relevant parameter, for the equal magneto of ac-dc axis inductance, the in the situation that of stator magnetic linkage constant amplitude and other parameter constants of motor, the torque of motor and sin δ are directly proportional, in the scope that δ changes at 0-90 degree, along with the increase of motor torque, angle of torsion also can increase thereupon.Magnetic linkage angle is angle of torsion and rotating speed position angle sum, if in the situation that not carrying out angle compensation, be equivalent to directly using rotating speed position angle as magnetic linkage angle, one timing of stator magnetic linkage amplitude, the in the situation that of little torque operation, because angle of torsion is less, so can not bring larger error, if the in the situation that of large torque, angle of torsion is larger, can bring very large flux linkage calculation error, thereby make whole DTC control system can not realize Expected Results, so it is necessary carrying out angle compensation accurately, it for salient pole rate, is not 1 magneto, the in the situation that of large torque operation, angle of torsion is larger, if do not adopt angle compensation, flux linkage calculation error also can be very large.

In closed loop compensation process, offset is carried out adopting while periodically calculating to the method for accumulator accumulation calculating, shown in (8):

sum＝sum+gel (8)

Wherein sum is offset angle accumulator, and its initial value is 0, gel is the offset angle of the rotor position angle calculating according to described formula (6); Accumulator is remembered the angle compensation value of this direct Torque Control control cycle, and in the calculating of the angle compensation in lower cycle of substitution, realizes the periodicity dynamic compensation of angle, and described periodic quantity is set to 0.3-3 motor electrical cycle.

Be the detailed process of magnetic linkage angle compensation as described in Figure 4, first by the phase calculation of the magnetic linkage calculating and setting magnetic linkage out, according to the angle calculation feature of tangent, and calculating magnetic linkage and the precedence relationship of setting magnetic linkage phase place, point situation is considered the differential seat angle of the two, as shown in Figure 4, will estimate motor magnetic linkage utilize arctan function to calculate its stator magnet chain angle, by target control magnetic linkage the target control magnetic linkage stator magnet chain angle of utilizing arctan function to calculate, then that the two is poor, because this angle difference under the general nominal situation of motor, should be at [pi/2, pi/2] between, so exceeded this scope, increase as the case may be the angle cycle π of a tangent, or reduce one-period π, be specially when be less than-pi/2 of the difference of the two, should increase one-period, when the difference of the two is greater than pi/2, should reduce one-period, the two the difference that has guaranteed like this output necessarily drops on [pi/2, pi/2] in interval.Because whole direct Torque Control, need certain action response time, so need to set a compensation cycle, each Periodic Compensation once, periodic quantity arranges and generally chooses 0.3-3 motor electrical cycle, set a compensation range, it is step-length operating valve value, within the scope of this, upgrade offset, if not within the scope of this, when namely target control magnetic linkage and calculating magnetic linkage phase place are more or less the same, do not need to upgrade offset, the angle compensation value that also adopts a compensation cycle to draw, compensator has adopted an accumulator pattern, because when actual value and calculated value difference angle are gel, if offset is gel, after this compensation cycle, between actual magnetic linkage and calculating magnetic linkage, phase difference approaches zero, the offset angle of next compensation cycle just approaches zero, to the two phase difference of next compensation cycle, can recover again again, in actual direct Torque Control, finally the phase difference value of the two can be stabilized to gel/2, adopt an accumulator benefit to be as long as after locking calculates phase difference between magnetic linkage and actual magnetic linkage and compensate, just offset is remembered in accumulator, thereby by reality accurately phase difference settle out, carry out angle compensation, the phase difference that calculates magnetic linkage and actual magnetic linkage is dropped in the scope of setting.In addition to carry out amplitude limit to the output valve of accumulator, prevent very large compensate, cause whole control system loss of stability.

Fig. 5 and Fig. 6 have compared in straight moment controlling system and adopt closed loop magnetic linkage method of estimation in the situation that carrying out angle compensation and not carrying out angle compensation, in two-phase rotating coordinate system, the calculated case of one phase magnetic linkage, as can be seen from the figure, carry out angle compensation and can effectively improve the estimation effect of magnetic linkage.

Fig. 7 adopts after angle compensation process, the situation of change of angle compensation calculated value.As can be seen from the figure, utilize the angle compensation value of the locking system that angle compensation computing module can be very fast, realize flux linkage calculation module stability, accurately angle compensation.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (2)

1. the permanent-magnetic synchronous motor stator magnetic linkage method of estimation based on direct torque control, is characterized in that: when initial control cycle calculates magnetic linkage, record in real time the three-phase voltage U of permagnetic synchronous motor _a, U _b, U _c, and three-phase current i _a, i _b, i _c, the described voltage and current under three-phase rotating coordinate system is transformed to the voltage u of α β coordinate system _α, u _β, current i _α, i _β; In control cycle of direct Torque Control according to formula (1) to described voltage u _α, u _βcarry out integral and calculating, obtain magnetic linkage according to a preliminary estimate

Wherein, R _sfor motor stator resistance;

By described magnetic linkage according to a preliminary estimate with target control magnetic linkage reference value

by PI control algolithm, obtain DC offset voltage compensation rate V _α, V _β; Wherein, according to formula (2), obtain the integration item sum of PI control algolithm _α, sum _β:

Wherein, K _ifor integral coefficient; sum _α', sum ' _βfor the integration item that a control cycle in direct Torque Control obtains, sum _α', sum ' _βinitial value is 0;

for target control magnetic linkage reference value:

Wherein, ψ ^*for the given control magnetic linkage of direct Torque Control, ψ ^*as target control magnetic linkage amplitude; θ is the stator magnet chain angle of target control magnetic linkage;

According to formula (3), obtain described DC offset voltage compensation rate V _α, V _β:

Wherein, K _pfor proportionality coefficient;

According to described DC offset voltage compensation rate V _α, V _β, according to formula (4), calculate the motor magnetic linkage that Flux estimator is estimated

When next control cycle, the motor magnetic linkage that utilizes a upper control cycle to estimate replace magnetic linkage according to a preliminary estimate

substitution formula (2) is calculated, and forms closed-loop regulating system; When closed-loop regulator realizes target control magnetic linkage

while dynamically following the tracks of, the estimation magnetic linkage of described Flux estimator

be motor magnetic linkage accurately.

2. a kind of magneto magnetic linkage method of estimation according to claim 1, it is characterized in that, utilize rotor-position sensor to draw the rotor position angle γ of motor under direct torque control, and described rotor position angle γ is carried out after closed-loop dynamic compensation, draw the stator magnet chain angle θ of described target control magnetic linkage; Described dynamic compensation calculates suc as formula shown in (5):

θ=γ+δ (5)

Wherein, γ is rotor position angle; δ is angle of torsion, and the offset angle of rotor position angle is equaled to described angle of torsion;

Described angle of torsion calculates suc as formula shown in (6):

Wherein,

described in serving as reasons

the target control magnetic linkage stator magnet chain angle of utilizing arctan function to calculate; for the estimation motor magnetic linkage calculating according to described formula (4) utilize the stator magnet chain angle of the motor magnetic linkage that arctan function calculates;

In closed loop compensation process, offset is carried out adopting while periodically calculating to the method for accumulator accumulation calculating, shown in (7):

sum=sum+gel (7)

Wherein sum is offset angle accumulator, and its initial value is 0, gel is the offset angle of the rotor position angle calculating according to described formula (6); Accumulator is remembered the angle compensation value of this direct Torque Control control cycle, and in the calculating of the angle compensation in lower cycle of substitution, realizes the periodicity dynamic compensation of angle, and described periodic quantity is set to 0.3-3 motor electrical cycle.

Images