阅读说明：本技术 一种直线游标永磁电机无差拍控制方法 (Dead-beat control method for linear vernier permanent magnet motor ) 是由 唐红雨 赵文祥 杨真理 沙鸥 于 2020-05-06 设计创作，主要内容包括：本发明涉及一种直线游标永磁电机无差拍控制方法,在传统DTC控制的基础上,通过引入速度反步控制器取代传统速度环PI调节器,采用无差拍控制器取代电流环PI调节器,采用改进双采样双更新的SVPWM替代传统的SVPWM调制模块。根据多次仿真,本发明在保持传统DTC控制的基础上,能有效减小系统的超调量,并能有效降低系统的推力脉动,提高系统的动态性能。(The invention relates to a dead-beat control method for a linear vernier permanent magnet motor, which is characterized in that on the basis of the traditional DTC control, a speed backstepping controller is introduced to replace a traditional speed loop PI regulator, a dead-beat controller is adopted to replace a current loop PI regulator, and an improved double-sampling double-updating SVPWM is adopted to replace a traditional SVPWM modulation module. According to multiple times of simulation, the method can effectively reduce the overshoot of the system, effectively reduce the thrust pulsation of the system and improve the dynamic performance of the system on the basis of keeping the traditional DTC control.)

1. A dead-beat control method for a linear vernier permanent magnet motor is characterized by comprising the following steps:

step 1: acquiring the actual speed v of the permanent magnet linear motor, and comparing the actual speed v with the given speed v^*The difference value delta v of (a) is used as a parameter of the backstepping controller; system disturbance quantity of permanent magnet linear motor is obtained

step 2: obtaining three-phase stator current i of permanent magnet linear motor_a、i_b、i_cObtaining a current component i after coordinate transformation_α、i_β(ii) a Three-phase stator phase voltage U of permanent magnet linear motor is obtained_a、U_b、U_cObtaining a voltage component u after coordinate transformation_αAnd u_βThe reference flux linkage psi under the two-phase static coordinate system is calculated according to the current component and the voltage component_α、ψ_β；

And step 3: the current component is transformed by a coordinate system to obtain a decoupled current i_qAnd i_dAccording to the decoupled current i_qAnd i_dCalculating the actual thrust F_e；

And 4, step 4: producing a given reference thrust by a backstepping control law

And 5: will i_q ^*、i_d ^*Taking the difference between the expected flux linkage and the reference flux linkage as an input parameter of the dead-beat controller, and obtaining a given reference voltage u through dead-beat control rate calculation_d、u_q；

Step 6: will give a reference voltage u_d、u_qObtaining a reference voltage vector component u after coordinate system transformation_α1、u_β1；

And 7: reference voltage vector component u_α1、u_β1And the PWM signals are input into the SVPWM adjusting module, and then the SVPWM adjusting module sends PWM signals with fixed switching frequency to the inverter to drive the motor to run.

2. The linear vernier permanent magnet motor deadbeat control method of claim 1 wherein said coordinate transformation is a three phase/two phase stationary coordinate transformation; the coordinate system is transformed into a two-phase stationary/two-phase rotating coordinate system.

3. The dead-beat control method of the linear vernier permanent magnet motor as claimed in claim 1, wherein the formula for calculating the reference flux linkage according to the current component and the voltage component in the step 2 is as follows:

wherein psi_α、ψ_βIs a flux linkage, psi, in a two-phase stationary coordinate system_sFor reference to the magnetic chain, R_sIs the stator resistance.

4. The linear vernier permanent magnet motor dead-beat control method according to claim 1, wherein the step 3 is performed according to the decoupled current i_qAnd i_dCalculating the actual thrust F_eThe formula of (1) is as follows:

wherein, F_eIs the electromagnetic thrust of the motor, v is the actual speed of the motor, tau_sFor LVPM motor stator pole pitch, P_nIs the pole pair number of the motor, psi_fIs a permanent magnet linkage, L_d、L_qIs the direct component and the quadrature component, omega, of the inductor in dq coordinate system_r＝n_pπν/τ_sThe rotor flux linkage electrical angular velocity of the motor.

5. The dead-beat control method of the linear vernier permanent magnet motor according to claim 1, wherein the backstepping control law in the step 4 is as follows:

wherein, F_e ^*Is a reference thrust; e.g. of the type_vTo define the speed error, e_v＝v-v^*；F_LIs the load resistance; m is the primary mass of the motor; b is a friction coefficient; k is a normal number;

6. the method for deadbeat control of linear vernier permanent magnet motor as claimed in claim 1 wherein said step 5 is performed by deadbeat control rate calculation to obtain said given reference voltage u_d、u_qThe formula of (1) is as follows:

wherein, T_sIs the sampling period, omega_rIs the electrical angular velocity.

7. The method for dead-beat control of linear vernier permanent magnet motor according to claim 1, wherein in step 7, the SVPWM adjusting module adopts a double sampling and double updating strategy, that is, when sampling of the current cycle is performed at the beginning and middle of each cycle, PWM is updated to the instruction of the previous cycle at the same time.

Technical Field

The invention relates to a linear vernier permanent magnet motor control technology, in particular to a linear vernier permanent magnet motor dead-beat control method based on a speed backstepping controller, which is suitable for long-stroke linear traction equipment.

Background

The rapid development of national economy and the rapid promotion of urbanization process improve the living standard of people, but the problems of imbalance and incoordination in the development of social economy are still outstanding. The mass population is rushed to cities and towns, so that the urban population is more and more, the number of cities is continuously increased, and the problem of urban traffic congestion is more and more prominent. Urban rail transit has become a main approach for solving urban traffic problems with the advantages of large transportation volume, less pollution, low energy consumption, rapidness, punctuality and the like.

As a core component of urban rail vehicles, an automotive traction motor is a key technology for ensuring safe and reliable operation of a locomotive, and research on the automotive traction motor is also widely focused by scholars in related fields. In terms of technical aspect, the traction motor for the vehicle mainly adopts two technical approaches of a rotary motor and a linear motor, the rotary motor needs to depend on the adhesive force between wheels and steel rails to drive, the starting, acceleration and deceleration, climbing and braking performances are limited to a certain extent, the transmission loss and the vehicle noise are large, certain requirements are made on the heights of the wheels, and the light weight and the miniaturization of the train are difficult to realize. The rail transit system driven by the linear motor can convert rotary motion into linear motion without an intermediate energy conversion device, has the remarkable advantages of high energy conversion efficiency, low noise, simple structure, strong climbing capability and the like, and can obtain stronger traction and braking performance and stable vehicle running. A Linear Vernier Permanent Magnet (LVPM) motor is a novel special motor, is a motor developed on the basis of a Linear primary Permanent Magnet motor, works by utilizing a magnetic flux switching principle, and is different from a pair of Permanent magnets but a plurality of pairs of Permanent magnets at the tooth end of a stator. The motor can generate larger thrust by utilizing the vernier effect of the motor at low speed, so that the motor is widely applied to the field of long-stroke of rail transit and the like. Therefore, the research of the linear motor system suitable for linear traction has important scientific, economic and social practical values.

Direct Torque Control (DTC) is a mature control strategy, and does not need to perform decoupling calculation on a controlled model, and has the advantages of good dynamic performance, good robustness, uncomplicated control law and the like. In the direct torque control, flux linkage and electromagnetic torque are used as control variables, and a simple hysteresis comparator is used for completing decoupling control, but the torque and flux linkage have large pulsation and poor adjustability. The LVPM motor system is a complex system with multivariable, strong coupling and nonlinearity, and the traditional DTC control performance is poor. In a traditional speed loop, a PI regulator is generally adopted, but the thrust and speed tracking of a linear vernier permanent magnet motor are often large in pulsation due to the output of inverter voltage. When the speed is changed suddenly, the output of the controller is limited by saturation, and at the moment, the motor can only output preset maximum thrust, so that the integral saturation phenomenon can be caused, the overshoot of the system is large, and the stabilization time is long. The traditional DTC adopts current hysteresis control for controlling flux linkage and thrust, only a single voltage vector can act in one period, and the problems of large flux linkage and thrust pulsation, unfixed inverter switching frequency and the like exist.

The dead beat direct torque control aims to make the error between the torque and the flux linkage and a given value zero at the end of a sampling period, has higher response speed and is easy to realize on a high-speed microprocessing chip. Scholars at home and abroad research and improve a deadbeat control algorithm, and some scholars theoretically design an optimal reference voltage vector for flux linkage and torque homodyne control of a motor, but the complexity is increased, the calculation of solving state variables is large, and the physical significance is unclear. Some researchers have studied the design and implementation problems of dead-beat direct torque control under the condition that the output voltage of a voltage source inverter is limited. In order to reduce time delay and improve the control performance of a current loop of a servo system, some scholars provide a robust prediction current control algorithm of a permanent magnet synchronous motor based on a dead-beat control principle. Some scholars provide an improved dead-beat predictive control algorithm and a novel dead-beat direct torque control method of an induction motor based on a predictive algorithm based on a dead-beat predictive control algorithm of Lagrange interpolation. Most of the learners study a dead-beat direct torque control method of an asynchronous motor, and can derive torque and a stator flux linkage control law theoretically, but the actual sampling period is limited, and the realization of zero error in 1 period cannot be met.

Disclosure of Invention

The invention provides a dead-beat control method for a linear vernier permanent magnet motor, which is used for solving the problems of slow speed response and large thrust pulsation in a linear vernier permanent magnet motor system adopting the traditional speed loop PI and current loop PI control.

The invention provides a dead-beat control method for a linear vernier permanent magnet motor, which comprises the following steps:

step 1: acquiring the actual speed v of the permanent magnet linear motor, and comparing the actual speed v with the given speed v^*The difference value delta v of (a) is used as a parameter of the backstepping controller; system disturbance quantity of permanent magnet linear motor is obtainedAs a parameter of another back-stepping controller;

step 2: obtaining three-phase stator current i of permanent magnet linear motor_a、i_b、i_cObtaining a current component i after coordinate transformation_α、i_β(ii) a Three-phase stator phase voltage U of permanent magnet linear motor is obtained_a、U_b、U_cObtaining a voltage component u after coordinate transformation_αAnd u_βThe reference flux linkage psi under the two-phase static coordinate system is calculated according to the current component and the voltage component_α、ψ_β；

And step 3: the current component is transformed by a coordinate system to obtain a decoupled current i_qAnd i_dAccording to the decoupled current i_qAnd i_dCalculating the actual thrust F_e；

And 4, step 4: producing a given reference thrust F by a backstepping control law_e ^*Calculating a given reference thrust F_e ^*With actual thrust F_eDifference of (a) F_e(ii) a Will actually push force F_eObtaining i through PI regulator_q ^*And d-axis reference current i_d ^*；

And 5: will i_q ^*、i_d ^*Taking the difference between the expected flux linkage and the reference flux linkage as an input parameter of the dead-beat controller, and obtaining a given reference voltage u through dead-beat control rate calculation_d、u_q；

Step 6: will give a referencePress u_d、u_qObtaining a reference voltage vector component u after coordinate system transformation_α1、u_β1；

And 7: reference voltage vector component u_α1、u_β1And the PWM signals are input into the SVPWM adjusting module, and then the SVPWM adjusting module sends PWM signals with fixed switching frequency to the inverter to drive the motor to run.

Further, the coordinate transformation is a three-phase/two-phase stationary coordinate transformation; the coordinate system is transformed into a two-phase stationary/two-phase rotating coordinate system.

Further, the formula for calculating the reference flux linkage according to the current component and the voltage component in step 2 is as follows:

wherein psi_α、ψ_βIs a flux linkage, psi, in a two-phase stationary coordinate system_sFor reference to the magnetic chain, R_sIs the stator resistance.

Further, according to the decoupled current i_qAnd i_dCalculating the actual thrust F_eThe formula of (1) is as follows:

wherein, F_eIs the electromagnetic thrust of the motor, v is the actual speed of the motor, tau_sFor LVPM motor stator pole pitch, P_nIs the pole pair number of the motor, psi_fIs a permanent magnet linkage, L_d、L_qIs the direct component and the quadrature component, omega, of the inductor in dq coordinate system_r＝n_pπν/τ_sThe rotor flux linkage electrical angular velocity of the motor.

Further, the backstepping control law in the step 4 is as follows:

wherein, F_e ^*Is a reference thrust; e.g. of the type_vTo define the speed error, e_v＝v-v^*；F_LIs the load resistance; m is the primary mass of the motor; b is a friction coefficient; k is a normal number;

further, in the step 5, the given reference voltage u is obtained through dead-beat control rate calculation_d、u_qThe formula of (1) is as follows:

wherein, T_sIs the sampling period, omega_rIs the electrical angular velocity.

Further, in step 7, the SVPWM adjusting module adopts a double sampling and double updating strategy, that is, when sampling of the present period is performed at the beginning and the middle of each period, PWM is updated to the instruction of the previous period at the same time.

The invention has the beneficial effects that:

1. the speed loop of a double closed loop motor system is changed into a speed backstepping controller, the disturbance quantity of the system is estimated by adopting an extended state observer, a control law is designed, and stability verification is carried out to obtain a thrust F_eThe interference resistance and the robustness of the system are improved by the reference quantity.

2. A dead beat controller is adopted to replace a conventional current loop, the voltage and the current at the next moment are calculated according to the flux linkage and the current at the current moment, and the voltage u is given_d、u_qThe control law and the design of a double-sampling and double-updating strategy of the SVPWM module improve the real-time property of PWM waves, and the whole strategy can ensure that the LVPM motor system has better dynamic propertyThe system can track the performance with the speed, and can reduce the overshoot of the system.

3. The invention is also suitable for the common non-primary permanent magnet type linear permanent magnet motor.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

FIG. 1 is a block diagram of the system of the present invention;

FIG. 2 is a block diagram of a speed step back controller;

FIG. 3 is a comparison graph of three PWM update strategies;

FIG. 4 is a voltage space vector distribution plot;

FIG. 5 is a dynamic performance simulation waveform diagram;

FIG. 6 is a simulation waveform diagram of abrupt thrust change

FIG. 7 is a flux linkage trajectory circle under different methods;

FIG. 8 is a graph of the speed and thrust response for a sudden change in speed.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 and 2, the displacement sensor measures the motor displacement in real time and obtains the actual speed v after derivation, and the actual speed v and the given speed v are compared^*Taking the difference as one of the input of the speed backstepping controller, regarding the load of the system as a disturbance quantity, and obtaining the disturbance quantity through an Extended State Observer (ESO)

As another input to the speed step-back controller, the passing speedControl law operation of degree backstepping controller generates reference thrust F_e ^*(ii) a Meanwhile, three-phase stator current and voltage are converted into a current component i through three-phase/two-phase static coordinates_α、i_βVoltage component u_α、u_βCalculating psi by flux linkage estimation_s(ii) a Then, the two-phase static/two-phase rotating coordinate transformation is carried out to obtain the current i after the motor is decoupled_qAnd i_dCalculating thrust F by thrust estimation_eReference thrust F_e ^*And the actual thrust force F_eMaking a difference, generating i through a PI regulator_q ^*As input to the deadbeat controller, a given flux linkage desired value ψ_s ^*With reference flux linkage psi_sThe difference is used as the input of the dead beat controller, and the current i is added_q ^*、i_d ^*As an input to a deadbeat controller; operating according to a designed voltage control law in a dead beat controller to obtain a voltage u_qAnd u_d. Then the vector control voltage u of the SVPWM modulation module is obtained through two-phase rotation/two-phase static coordinate transformation_α1And u_β1In the SVPWM module, a double-sampling and double-updating strategy is adopted, so that the sampling delay can be reduced, the PWM waveform is generated and output to the inverter, the output voltage of the inverter is controlled, and the speed and the thrust of the motor are controlled more stably and accurately.