CN111769779A - PMSM direct torque control method based on improved Luenberger observer - Google Patents

Abstract

The PMSM direct torque control method based on the improved Luenberger observer comprises the following steps: respectively carrying out Clark coordinate transformation on a stator three-phase current signal and a stator three-phase voltage signal of a high-speed permanent magnet synchronous motor (9) to obtain a stator current signal and a stator voltage signal under a two-phase static DQ coordinate system; secondly, calculating to obtain an estimated electromagnetic torque value; at the same time, the stator current signal and the stator voltage signal and the given control system rotating speed signal，Obtaining the difference value between the estimated value and the reference torque of the motor rotor through an improved Luenberger observer algorithm, and adjusting the difference value to the reference torque of the motor through a rotating speed PI regulator; (III) obtaining a stator flux linkage increment through a stator flux linkage hysteresis comparator and obtaining a control signal through a traditional bang-bang controller; the method has the advantages that the observation rotating speed deviation existing in the traditional observation algorithm is corrected by introducing the relation function, the high-frequency pulsation error of the observation rotating speed is eliminated by introducing the low-pass filter, and the accurate observation of the rotating speed of the motor rotor is realized.

Description

PMSM direct torque control method based on improved Luenberger observer

Technical field:

The invention belongs to the field of speed sensorless control of a high-speed motor, and in particular relates to a direct torque control method of a high-speed permanent magnet synchronous motor and an improved Luenberger observer algorithm.

Background technique:

Compared with constant-speed motors, high-speed permanent magnet synchronous motors have many advantages: small rotational inertia, large power density, small size, high work efficiency and fast dynamic response speed, so they are more and more widely used in high-precision machining and high-performance machinery. . The main idea of direct torque control technology is to directly control the torque and flux linkage of the AC motor in the two-phase static DQ coordinate system, so that the stator flux linkage of the motor is approximately circular. Compared with the vector control strategy, the direct torque control strategy cancels the complex rotation coordinate transformation process in the control process. The algorithm is simple and the system dynamic response is fast. It is very suitable for application in the control system of high-speed permanent magnet synchronous motors.

In order to accurately control the high-speed permanent magnet synchronous motor, it is necessary to obtain the speed information of the motor rotor at all times. The speed sensor installed on the rotor shaft (such as tachogenerator, photoelectric encoder, resolver, etc.) can detect the real-time speed of the rotor. However, the complex speed sensor has the following problems in the high-speed motor control system: due to the high-speed motor rotor The high-speed, high-precision speed sensor will increase the volume and cost of the system; a lot of high-frequency noise signals will be generated during the operation of the high-speed motor, so a filtering device needs to be introduced to filter out the high-order harmonic signals, thereby increasing the cost of the system ;The speed sensor installed on the rotor of the high-speed permanent magnet synchronous motor will increase the rotational inertia of the rotor, thereby increasing the energy loss of the system, and the use of the speed sensor in some harsh environments will greatly shorten its life, and some occasions are even not allowed to install speed sensor.

Due to the high rotor speed of the high-speed permanent magnet synchronous motor, there are few sensors that can be used for the detection of the rotor speed of the high-speed permanent magnet synchronous motor. Some experts and scholars have carried out a lot of research on speed sensorless technology. The speed sensorless technology can estimate the rotor speed based on parameters such as current, voltage, resistance, inductance in the stator winding, replacing the speed sensor installed on the motor rotor. Compared with other speed sensorless algorithms, the Luenberger observer has the advantages of relatively simple algorithm, fast dynamic response, and good robustness. It is very suitable for detecting the rotor speed of high-speed permanent magnet synchronous motors, thereby improving the control performance of the system. Therefore, the research on sensorless technology of high-speed permanent magnet synchronous motor has important theoretical and practical value.

SUMMARY OF THE INVENTION

Purpose of invention:

The invention provides a direct torque control method of a high-speed permanent magnet synchronous motor and an improved Luenberger observer algorithm, which aim to solve the problems of error and speed pulsation in the observed rotation speed of the motor rotor of a high-speed permanent magnet synchronous motor control system.

Technical solutions:

The direct torque control method of high-speed permanent magnet synchronous motor based on the improved Luenberger observer is characterized in that: the method steps are as follows:

(1), the stator three-phase current signal i _A , i _B , i _C and the stator three-phase voltage signal u _A , u _B , u _C of the high-speed permanent magnet synchronous motor (9) are respectively transformed by Clark coordinates to obtain a two-phase static state Stator current signals i _D , i _Q and stator voltage signals u _D , u _Q in the DQ coordinate system;

(2) The stator current signals i _D , i _Q and the stator voltage signals u _D , u _Q are converted to obtain the components ψ _D , ψ _Q of the stator flux linkage vector in the two-phase static DQ coordinate system and the stator flux linkage amplitude | ψ _S |; stator current signals i _D , i _Q and components ψ _D , ψ _Q signals are based on the torque estimation equation _te = p ₀ (ψ _D i _Q -ψ _Q i _D ), where p ₀ is the number of motor pole pairs, The electromagnetic torque estimation value te is obtained by calculation; at the same time, the stator current signals i _D , _{i Q} and the stator voltage signals u _D , u _Q and the given control system speed signal n are obtained by the improved Luenberger observer algorithm to obtain the motor rotor speed estimation The value n ^* , the difference between n and n ^* goes through the speed PI regulator to the motor reference torque t _e ^* ;

In steps (3) and “(2)”, the difference between the motor reference torque and the estimated value of the electromagnetic torque is obtained through the torque hysteresis comparator to obtain the torque increment Δt; define the equivalent inductance L _q of the motor quadrature axis and the direct axis The ratio of the equivalent inductance L _d is the salient pole ratio ρ, and the reference stator flux linkage amplitude |ψ _S ^* | is a constant, satisfying |ψ _S ^* |≤ρ/(ρ-1)ψ _f , where ψ _f is the permanent magnet The magnitude of the flux linkage vector generated by the rotor; the difference between |ψ _S ^* | and |ψ _S | obtains the stator flux linkage increment Δψ through the stator flux linkage hysteresis comparator; Δψ and Δt signals pass through the traditional bang-bang controller (6 ) to obtain the control signal (Δt is the difference between the reference torque and the feedback torque), and finally the voltage-type inverter (8) is driven by the control signal to control the high-speed permanent magnet synchronous motor (9), and the high-speed permanent magnet synchronous motor is completed. control.

(2) The steps of obtaining the estimated value of the rotor speed of the motor through the improved Luenberger observer algorithm in the step are as follows:

u_Q、i_Q经反电势Q轴分量计算得到Q轴反电势估算分量

将

和

信号通过低通滤波法减小反电势分量波形的脉动，得到优化后的反电势分量信号

和

；u _D , i _D are calculated by the D-axis component of the back-EMF in the DQ coordinate system to obtain the estimated component of the D-axis back-EMF

u _Q and i _Q are calculated by the Q-axis component of the back-EMF to obtain the estimated component of the Q-axis back-EMF

Will

and

The pulsation of the back EMF component waveform is reduced by the low-pass filtering method, and the optimized back EMF component signal is obtained.

and

;

和

一同经Luenberger观测器转子转速计算得到观测器观测转速n，，将观测转速和给定控制系统转速信号n，经改进型Luenberger观测器转速修正算法得到电机转子转速估算值n^*。The total parameter _ke of the _Luenberger observer, the second parameter ke2 , the flux linkage amplitude generated by the permanent magnet of the rotor of the high-speed permanent magnet synchronous motor |ψ _f |, the motor stator inductance L, the back EMF component

and

At the same time, the observed speed n of the observer is obtained by calculating the rotor speed of the Luenberger observer, and the estimated value of the motor rotor speed n ^* is obtained by the improved Luenberger observer speed correction algorithm by combining the observed speed and the given control system speed signal n.

The back-EMF component algorithm in the DQ coordinate system is as follows: Design a back-EMF observer, and the observer equation is (the D-axis component and the back-EMF Q-axis component are common):

为两相静止DQ坐标系下的定子电流估算矢量；L为定子电感；

为两相静止DQ坐标系下的定子反电动势估算矢量；e_s＝[e_D,e_Q]^T为两相静止DQ坐标系下的定子反电动势矢量；u_s＝[u_D,u_Q]^T为两相静止DQ坐标系下的定子电压向量；

为定子电流估算矢量的瞬时变化率；k_e1，k_e2为Luenberger观测器的增益系数；R为电机定子电阻；In the formula: i _s = [i _D , i _Q ] ^T is the stator current vector in the two-phase static DQ coordinate system;

is the estimated vector of the stator current in the two-phase static DQ coordinate system; L is the stator inductance;

is the stator back EMF estimation vector in the two-phase static DQ coordinate system; _es = [e _D , e _Q ] ^T is the stator back EMF vector in the two-phase static DQ coordinate system; u _s = [u _D , u _Q ] ^T is the stator voltage vector in the two-phase static DQ coordinate system;

is the instantaneous rate of change of the stator current estimation vector; k _e1 , k _e2 are the gain coefficients of the Luenberger observer; R is the motor stator resistance;

The stator back EMF estimation equation can be obtained by subtracting (1) from equation (2)

Set _ke = _ke1 + _ke2 , the stability condition of the observer is _ke > 0, the eigenvalue of this observer is _{-ke /L, the larger the value of ke ,} the faster the convergence speed of the observer, but also will lead to greater overshoot. Formula (3) is expressed in the following form

的相位角

由反电动势估算值

的相位角

和补偿角θ_comp相加求出The rotor speed of the Luenberger observer is calculated to obtain the observed speed n of the observer. The algorithm is as follows: Back EMF

the phase angle of

Estimated from back EMF

the phase angle of

Add the compensation angle θ _comp to get

in the formula

是估测反电动势矢量模值；

is the estimated back-EMF vector modulus value;

According to Figure 3, using the Pythagorean theorem, we can get

in the formula

Solving equation (9), the estimation formula of rotor angular velocity ω can be obtained

即Since the exact value of the actual angular velocity ω of the motor rotor cannot be detected directly, ω in the estimation formula of θ _comp should be

which is

与电机转子转速观测值n’之间存在固定的关系：

Motor rotor angular velocity estimate

There is a fixed relationship with the motor rotor speed observation n':

The modified Luenberger observer speed correction algorithm is as follows:

That is to use the compensation algorithm to correct the deviation of the observed value of the motor rotor speed of the observer. Specifically, the speed signal of the given control system is set as the independent variable x, and the ratio of the observed value of the motor rotor speed n' to x is the dependent variable y. relational function

y=f(x), in the coordinate system, make a scatter plot of the function to x in the interval [n ₁ , n _k ], n ₁ ～n _k are the k speed signals given by the control system, and then scatter the points The relationship function image obtained by curve fitting is a quadratic function image, and its expression is: y=ax ² -bx+c, a, b, and c are the parameters for fitting the quadratic function; substitute the motor given speed value into From the relationship function, the ratio of the observed speed of the motor to the actual speed can be obtained, and then the relationship function is multiplied by the given speed to obtain the revised estimated value of the rotor speed.

Advantage effect:

The beneficial effects of the present invention are:

Aiming at the problems of high-speed permanent magnet synchronous motor direct torque control system observation speed error and large observation speed fluctuation, an improved Luenberger observer algorithm is proposed. By introducing a low-pass filter to eliminate the high-frequency pulsation error of the observed speed, the accurate observation of the rotor speed of the motor is realized.

Description of drawings

Fig. 1 is the direct torque control principle block diagram of the high-speed permanent magnet synchronous motor based on the improved Luenberger observer of the present invention;

Fig. 2 is the principle block diagram of the improved Luenberger observer algorithm of the present invention;

Fig. 3 is the Luenberger observer phasor diagram of the present invention;

FIG. 4 is a curve fitting diagram of the rotational speed error of the improved Luenberger observer of the present invention and a given rotational speed.

Description of reference numbers:

1. Speed PI regulator; 2. Torque estimation module; 3. Stator flux linkage estimation module; 4. Stator flux linkage hysteresis comparator; 5. Torque hysteresis comparator; 6. Switching voltage vector selection table module; 7. Clark coordinate transformation module; 8. Voltage inverter; 9. High-speed permanent magnet synchronous motor; 10. Improved Luenberger observer module; 11. Back-EMF D-axis component calculation module; 12. Back-EMF Q-axis component calculation Module; 13. Low-pass filter; 14. Luenberger observer rotor speed calculation module; 15. Improved Luenberger observer speed correction module.

Detailed ways

The direct torque control method of high-speed permanent magnet synchronous motor based on the improved Luenberger observer is characterized in that: the method steps are as follows:

(1), the stator three-phase current signal i _A , i _B , i _C and the stator three-phase voltage signal u _A , u _B , u _C of the high-speed permanent magnet synchronous motor (9) are respectively transformed by Clark coordinates to obtain a two-phase static state Stator current signals i _D , i _Q and stator voltage signals u _D , u _Q in the DQ coordinate system;

(2) The stator current signals i _D , i _Q and the stator voltage signals u _D , u _Q are converted to obtain the components ψ _D , ψ _Q of the stator flux linkage vector in the two-phase static DQ coordinate system and the stator flux linkage amplitude | ψ _S |; stator current signals i _D , i _Q and components ψ _D , ψ _Q signals are based on the torque estimation equation _te = p ₀ (ψ _D i _Q -ψ _Q i _D ), where p ₀ is the number of motor pole pairs, The electromagnetic torque estimation value te is obtained by calculation; at the same time, the stator current signals i _D , _{i Q} and the stator voltage signals u _D , u _Q and the given control system speed signal n are obtained by the improved Luenberger observer algorithm to obtain the motor rotor speed estimation The value n ^* , the difference between n and n ^* goes through the speed PI regulator to the motor reference torque t _e ^* ;

In steps (3) and “(2)”, the difference between the motor reference torque and the estimated value of the electromagnetic torque is obtained through the torque hysteresis comparator to obtain the torque increment Δt; define the equivalent inductance L _q of the motor quadrature axis and the direct axis The ratio of the equivalent inductance L _d is the salient pole ratio ρ, and the reference stator flux linkage amplitude |ψ _S ^* | is a constant, satisfying |ψ _S ^* |≤ρ/(ρ-1)ψ _f , where ψ _f is the permanent magnet The magnitude of the flux linkage vector generated by the rotor; the difference between |ψ _S ^* | and |ψ _S | obtains the stator flux linkage increment Δψ through the stator flux linkage hysteresis comparator; Δψ and Δt signals pass through the traditional bang-bang controller (6 ) to obtain the control signal (Δt is the difference between the reference torque and the feedback torque), and finally the voltage-type inverter (8) is driven by the control signal to control the high-speed permanent magnet synchronous motor (9), and the high-speed permanent magnet synchronous motor is completed. control.

(2) The steps of obtaining the estimated value of the rotor speed of the motor through the improved Luenberger observer algorithm in the step are as follows:

u_Q、i_Q经反电势Q轴分量计算得到Q轴反电势估算分量

将

和

信号通过低通滤波法减小反电势分量波形的脉动，得到优化后的反电势分量信号

和

u _D , i _D are calculated by the D-axis component of the back-EMF in the DQ coordinate system to obtain the estimated component of the D-axis back-EMF

u _Q and i _Q are calculated by the Q-axis component of the back-EMF to obtain the estimated component of the Q-axis back-EMF

Will

and

The pulsation of the back EMF component waveform is reduced by the low-pass filtering method, and the optimized back EMF component signal is obtained.

and

和

一同经Luenberger观测器转子转速计算得到观测器观测转速n，，将观测转速和给定控制系统转速信号n，经改进型Luenberger观测器转速修正算法得到电机转子转速估算值n^*。The total parameter _ke of the _Luenberger observer, the second parameter ke2 , the flux linkage amplitude generated by the permanent magnet of the rotor of the high-speed permanent magnet synchronous motor |ψ _f |, the motor stator inductance L, the back EMF component

and

At the same time, the observed speed n of the observer is obtained by calculating the rotor speed of the Luenberger observer, and the estimated value of the motor rotor speed n ^* is obtained by the improved Luenberger observer speed correction algorithm by combining the observed speed and the given control system speed signal n.

The back-EMF component algorithm in the DQ coordinate system is as follows: Design a back-EMF observer, and the observer equation is (the D-axis component and the back-EMF Q-axis component are common):

为两相静止DQ坐标系下的定子电流估算矢量；L为定子电感；

为两相静止DQ坐标系下的定子反电动势估算矢量；e_s＝[e_D,e_Q]^T为两相静止DQ坐标系下的定子反电动势矢量；u_s＝[u_D,u_Q]^T为两相静止DQ坐标系下的定子电压向量；

为定子电流估算矢量的瞬时变化率；k_e1，k_e2为Luenberger观测器的增益系数；R为电机定子电阻；In the formula: i _s = [i _D , i _Q ] ^T is the stator current vector in the two-phase static DQ coordinate system;

is the estimated vector of the stator current in the two-phase static DQ coordinate system; L is the stator inductance;

is the stator back EMF estimation vector in the two-phase static DQ coordinate system; _es = [e _D , e _Q ] ^T is the stator back EMF vector in the two-phase static DQ coordinate system; u _s = [u _D , u _Q ] ^T is the stator voltage vector in the two-phase static DQ coordinate system;

is the instantaneous rate of change of the stator current estimation vector; k _e1 , k _e2 are the gain coefficients of the Luenberger observer; R is the motor stator resistance;

The stator back EMF estimation equation can be obtained by subtracting (1) from equation (2)

Set _ke = _ke1 + _ke2 , the stability condition of the observer is _ke > 0, the eigenvalue of this observer is _{-ke /L, the larger the value of ke ,} the faster the convergence speed of the observer, but also will lead to greater overshoot. Formula (3) is expressed in the following form

的相位角

由反电动势估算值

的相位角

和补偿角θ_comp相加求出The rotor speed of the Luenberger observer is calculated to obtain the observed speed n of the observer. The algorithm is as follows: Back EMF

the phase angle of

Estimated from back EMF

the phase angle of

Add the compensation angle θ _comp to get

in the formula

是估测反电动势矢量模值；

is the estimated back-EMF vector modulus value;

According to Figure 3, using the Pythagorean theorem, we can get

in the formula

Solving equation (9), the estimation formula of rotor angular velocity ω can be obtained

即Since the exact value of the actual angular velocity ω of the motor rotor cannot be detected directly, ω in the estimation formula of θ _comp should be

which is

与电机转子转速观测值n’之间存在固定的关系：

Motor rotor angular velocity estimate

There is a fixed relationship with the motor rotor speed observation n':

The modified Luenberger observer speed correction algorithm is as follows:

That is to use the compensation algorithm to correct the deviation of the observed value of the motor rotor speed of the observer. Specifically, the speed signal of the given control system is set as the independent variable x, the ratio of the observed value of the motor rotor speed n' to x is the dependent variable y, and the establishment of relational function

y=f(x), in the coordinate system, make a scatter plot of the function to x in the interval [n ₁ , n _k ], n ₁ ～n _k are the k speed signals given by the control system, and then scatter the points The relationship function image obtained by curve fitting is a quadratic function image, and its expression is: y=ax ² -bx+c, a, b, and c are the parameters for fitting the quadratic function; substitute the motor given speed value into From the relationship function, the ratio of the observed speed of the motor to the actual speed can be obtained, and then the relationship function is multiplied by the given speed to obtain the revised estimated value of the rotor speed.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The present invention proposes a high-speed permanent magnet synchronous motor direct torque control system based on the improved Luenberger observer algorithm, as shown in FIG. 1 , wherein the stator three-phase current signals i _A , i _B , i _C , the stator three-phase voltage signals u _A , u _B , u _C are obtained through the Clark coordinate transformation module 7 to obtain the stator current signals i _D , i _Q , the stator voltage signals u _D , u _Q in the two-phase static DQ coordinate system, and the signal The electromagnetic torque _te and the stator flux linkage amplitude |ψ _s 10 Obtain the estimated value of the rotor speed of the motor, and the estimated value of the rotor speed obtains the reference torque t _e ^* of the motor through the speed PI regulator; the difference between the reference torque and the estimated torque obtains the torque increment Δt through the torque hysteresis comparator 5; The difference between the reference flux linkage and the estimated flux linkage is obtained through the stator flux linkage hysteresis comparator 4 to obtain the stator flux linkage increment Δψ; the switching voltage vector selection table selects the appropriate voltage space according to the stator flux linkage increment value and the electromagnetic torque increment value The vector acts on the high-speed permanent magnet synchronous motor 9 through the voltage inverter 8 to complete the control of the high-speed permanent magnet synchronous motor.

u_Q、i_Q经反电势Q轴分量计算模块12得到Q轴反电势估算分量

由于高速永磁同步电机转子转速很高，此时估算得到的

和

波形存在较大的脉动，将

和

信号通过低通滤波器13可以大幅减小反电势分量波形的脉动，得到优化后的反电势分量信号

和

Luenberger观测器总参数k_e、第二参数k_e2、高速永磁同步电机转子磁链幅值ψ_f、电机定子电感L、反电势分量

和

一同经Luenberger观测器转子转速计算模块14得到观测器估算转速n，，此时得到的观测器估算转速与电机实际转速相比存在较大误差，将观测转速n，和参考转速n经过改进型Luenberger观测器转速修正模块15得到修正后的观测转速n^*。Fig. 2 is the principle block diagram of the improved Luenberger observer algorithm of the present invention, wherein u _D , i _D obtain the estimated D-axis back-EMF component through the back-EMF D-axis component calculation module 11

u _Q , i _Q obtain the Q-axis back-EMF estimated component through the back-EMF Q-axis component calculation module 12

Due to the high rotor speed of the high-speed permanent magnet synchronous motor, the estimated

and

There is a large pulsation in the waveform, the

and

The signal passing through the low-pass filter 13 can greatly reduce the pulsation of the back EMF component waveform, and obtain the optimized back EMF component signal

and

Luenberger observer total parameter _ke , second parameter _ke2 , high-speed permanent magnet synchronous motor rotor flux linkage amplitude ψ _f , motor stator inductance L, back EMF component

and

At the same time, the estimated observer speed n is obtained through the Luenberger observer rotor speed calculation module 14, and the estimated observer speed obtained at this time has a large error compared with the actual speed of the motor. The observer rotational speed correction module 15 obtains the corrected observed rotational speed n ^* .

The traditional Luenberger observer design is based on the stator voltage equation of the permanent magnet synchronous motor mathematical model in the DQ coordinate system, which can be expressed as the following vector form

In the formula: i _s = [i _D , i _Q ] ^T is the stator current vector in the two-phase static DQ coordinate system; u _s = [u _D , u _Q ] ^T is the stator voltage vector in the two-phase static DQ coordinate system ; _es = [e _D , e _Q ] ^T is the stator back electromotive force vector under the two-phase static DQ coordinate system.

Among them, e _D and e _Q contain the speed and position information of the rotor, but the back EMF cannot be directly detected by the control system, so a back EMF observer needs to be designed, and the observer equation is

为两相静止DQ坐标系下的定子电流估算向量；

为两相静止DQ坐标系下的定子反电动势估算向量；k_e1，k_e2为Luenberger观测器的增益系数。in the formula

Estimated vector for the stator current in the two-phase static DQ coordinate system;

are the stator back EMF estimation vectors in the two-phase static DQ coordinate system; ke1 and _ke2 are the gain coefficients of the _Luenberger observer.

The stator back EMF estimation equation can be obtained by subtracting (1) from equation (2)

Set _ke = _ke1 + _ke2 , the stability condition of the observer is _ke > 0, the eigenvalue of this observer is _{-ke /L, the larger the value of ke ,} the faster the convergence speed of the observer, but also will bring greater overshoot, so the value of _ke should be appropriately selected. Equation (3) can be expressed in the following form

In order to facilitate the phasor analysis, _ke2 > 0 can be set, and the phasor diagram corresponding to equation (4) is shown in Figure 3.

的相位角

可由反电动势估算值

的相位角

和补偿角θ_comp相加求出In the figure, θ _comp is the compensation angle. As can be seen from the figure, the back EMF

the phase angle of

can be estimated from the back EMF

the phase angle of

Add the compensation angle θ _comp to get

in the formula

According to Figure 3, using the Pythagorean theorem, we can get

in the formula

Solving equation (9), the estimation formula of rotor angular velocity ω can be obtained

即Since the exact value of the rotor angular velocity ω cannot be detected directly, ω in the θ _comp estimation formula should be

which is

The motor speed observed by the traditional Luenberger observer is not very accurate, the observed speed waveform has pulsation, and the stable value of the motor speed is also deviated. The motor speed observed by the Luenberger observer is larger than the actual speed, and the higher the motor speed, the greater the error. In order to solve this problem and reduce the steady-state rotational speed pulsation of the observer, the present invention proposes a compensation algorithm to correct the rotational speed deviation of the observer.

Table 1 shows the actual speed value of the motor and the observed speed value of the observer. In the range from n ₁ to n _k (k is an arbitrary natural number ≥ 3), there is a large deviation between the actual speed of the motor and the observed speed, and with the increase of the speed , the ratio of the observed speed to the actual speed is getting larger and larger, and the deviation between the observed speed and the actual speed is not linear, and the observer error cannot be corrected simply by adding a proportional coefficient. The relationship between the actual motor speed (given speed) and the observer error is analyzed below.

Table 1 The actual speed of the motor and the speed value observed by the observer

Fig. 4 is the function fitting curve diagram of the present invention, let the given speed of the motor be the independent variable x, the ratio of the observed speed to the actual speed is the dependent variable y, establish a relationship function y=f(x), and make a function pair x in the coordinate system In the scatter plot in the interval [n ₁ , n _k ], curve fitting is performed on the scatter plot to obtain the relational function image, which is a quadratic function image, and its expression is: y=ax ² -bx+c. Substitute the given speed value of the motor into the relationship function to obtain the ratio of the observed speed to the actual speed of the motor, and then multiply the relationship function by the given speed to obtain the corrected observed speed.

In conclusion, the present invention belongs to the field of speed sensorless control of high-speed motors, and in particular relates to a direct torque control system of a high-speed permanent magnet synchronous motor and an improved Luenberger observer algorithm. The purpose is to solve the problem of the error and the speed pulsation of the observed speed of the rotor of the high-speed permanent magnet synchronous motor control system. The motor speed observed by the traditional Luenberger observer algorithm is not very accurate, the observed speed waveform has pulsation, and the stable value of the motor speed is also deviated. The motor speed observed by the Luenberger observer is larger than the actual speed, and the higher the motor speed, the error bigger. In order to solve this problem and reduce the steady-state rotational speed pulsation of the observer, the present invention proposes an improved Luenberger observer algorithm, which analyzes the deviation between the actual rotational speed of the motor and the rotational speed value observed by the observer, and sets the given rotational speed of the motor as the independent variable x , the ratio of the observed speed to the actual speed is the dependent variable y, establish a relational function f(x), draw a scatter plot of the function x in the interval [n ₁ , n _k ] in the coordinate system, and then curve the scatter plot The expression of the relationship function is obtained by fitting, and the relationship between the actual speed of the motor and the given speed is obtained, and the high-frequency vibration error of the observed speed is eliminated by introducing a low-pass filter, and the accurate observation of the rotor speed of the motor is realized.

Claims (5)

1. based on the high-speed permanent magnet synchronous motor direct torque control method of improving Luenberger observer, it is characterized in that: the method steps are as follows: (1), the stator three-phase current signal i _A , i _B , i _C and the stator three-phase voltage signal u _A , u _B , u _C of the high-speed permanent magnet synchronous motor (9) are respectively transformed by Clark coordinates to obtain a two-phase static state Stator current signals i _D , i _Q and stator voltage signals u _D , u _Q in the DQ coordinate system; (2) The stator current signals i _D , i _Q and the stator voltage signals u _D , u _Q are converted to obtain the components ψ _D , ψ _Q of the stator flux linkage vector in the two-phase static DQ coordinate system and the stator flux linkage amplitude | ψ _S |; stator current signals i _D , i _Q and components ψ _D , ψ _Q signals are based on the torque estimation equation _te = p ₀ (ψ _D i _Q -ψ _Q i _D ), where p ₀ is the number of motor pole pairs, The electromagnetic torque estimation value te is obtained by calculation; at the same time, the stator current signals i _D , _{i Q} and the stator voltage signals u _D , u _Q and the given control system speed signal n are obtained by the improved Luenberger observer algorithm to obtain the motor rotor speed estimation The value n ^* , the difference between n and n ^* goes through the speed PI regulator to the motor reference torque t _e ^* ; In steps (3) and “(2)”, the difference between the motor reference torque and the estimated value of the electromagnetic torque is obtained through the torque hysteresis comparator to obtain the torque increment Δt; define the equivalent inductance L _q of the motor quadrature axis and the direct axis The ratio of the equivalent inductance L _d is the salient pole ratio ρ, and the reference stator flux linkage amplitude |ψ _S ^* | is a constant, satisfying |ψ _S ^* |≤ρ/(ρ-1)ψ _f , where ψ _f is the permanent magnet The magnitude of the flux linkage vector generated by the rotor; the difference between |ψ _S ^* | and |ψ _S | obtains the stator flux linkage increment Δψ through the stator flux linkage hysteresis comparator; Δψ and Δt signals pass through the traditional bang-bang controller (6 ) to obtain a control signal, and finally the voltage-type inverter (8) is driven by the control signal to control the high-speed permanent magnet synchronous motor (9) to complete the control of the high-speed permanent magnet synchronous motor. 2. the high-speed permanent magnet synchronous motor direct torque control method based on improved Luenberger observer algorithm according to claim 1, is characterized in that: (2) The steps of obtaining the estimated value of the rotor speed of the motor through the improved Luenberger observer algorithm in the step are as follows: u _D , i _D are calculated by the D-axis component of the back-EMF in the DQ coordinate system to obtain the estimated component of the D-axis back-EMF

u _Q and i _Q are calculated by the Q-axis component of the back-EMF to obtain the estimated component of the Q-axis back-EMF

Will

and

The pulsation of the back EMF component waveform is reduced by the low-pass filtering method, and the optimized back EMF component signal is obtained.

and

The total parameter _ke of the _Luenberger observer, the second parameter ke2 , the flux linkage amplitude generated by the permanent magnet of the rotor of the high-speed permanent magnet synchronous motor |ψ _f |, the motor stator inductance L, the back EMF component

and

At the same time, the observed speed n' of the observer is obtained by calculating the rotor speed of the Luenberger observer, and the estimated value n ^* of the motor rotor speed is obtained by the improved Luenberger observer speed correction algorithm by combining the observed speed and the given control system speed signal n. 3. the high-speed permanent magnet synchronous motor direct torque control method based on improved Luenberger observer algorithm according to claim 2, is characterized in that: the back EMF component algorithm under DQ coordinate system is as follows: design back EMF observer, observe The device equation is:

In the formula: i _s =[i _D , i _Q ] ^T is the stator current vector in the two-phase static DQ coordinate system;

is the estimated vector of the stator current in the two-phase static DQ coordinate system; L is the stator inductance;

is the stator back EMF estimation vector in the two-phase static DQ coordinate system; _es = [e _D , e _Q ] ^T is the stator back EMF vector in the two-phase static DQ coordinate system; u _s = [u _D , u _Q ] ^T is the stator voltage vector in the two-phase static DQ coordinate system;

is the instantaneous rate of change of the stator current estimation vector; k _e1 , k _e2 are the gain coefficients of the Luenberger observer; R is the motor stator resistance; The stator back EMF estimation equation is obtained by subtracting (1) from equation (2)

Set _ke = _ke1 + _ke2 , the stability condition of the observer is _ke > 0, the eigenvalue of this observer is _{-ke /L, the larger the value of ke ,} the faster the convergence rate of the observer, the formula ( 3) is expressed in the following form

4. the high-speed permanent magnet synchronous motor direct torque control method based on improved Luenberger observer algorithm according to claim 3, is characterized in that: Luenberger observer rotor speed calculation obtains observer observation speed n ' algorithm as follows: back electromotive force

the phase angle of

Estimated from back EMF

the phase angle of

Add the compensation angle θ _comp to get

in the formula

is the estimated back-EMF vector modulus value; Using the Pythagorean theorem, we get

in the formula

Solving equation (9), we can get the estimation formula of rotor angular velocity ω

Because the exact value of the actual angular velocity ω of the motor rotor cannot be directly detected, ω in the estimation formula of θ _comp should be

which is

Motor rotor angular velocity estimate

There is a fixed relationship with the motor rotor speed observation n':

5. the high-speed permanent magnet synchronous motor direct torque control method based on improved Luenberger observer algorithm according to claim 4, is characterized in that: improved Luenberger observer rotational speed correction algorithm is as follows: That is to use the compensation algorithm to correct the deviation of the observed value of the motor rotor speed of the observer. Specifically, the speed signal of the given control system is set as the independent variable x, and the ratio of the observed value of the motor rotor speed n' to x is the dependent variable y. The relational function y=f(x), in the coordinate system, make a scatter plot of the function pair x in the interval [n ₁ , n _k ], n ₁ ～n _k are k speed signals given by the control system, and then The relationship function image obtained by curve fitting of the scatter diagram is a quadratic function image, and its expression is: y=ax ² -bx+c, a, b, and c are the parameters of the fitting quadratic function; The value is substituted into the relationship function to obtain the ratio of the motor observed speed to the actual speed, and then the relationship function is multiplied by the given speed to obtain the revised rotor speed estimate.

Images