CN108649850A - Improve the internal permanent magnet synchronous motor current control method of UDE - Google Patents

Abstract

A built-in permanent magnet synchronous motor current control method that improves UDE: In the current control cycle, the actual speed of the motor, the rotor position angle, the three-phase current of the motor, and the DC bus voltage are sampled, and the three-phase rotating coordinate system is used to reach the two-phase static Coordinate system transformation solves the actual current of the d and q axes; obtains the reference current of the q axis according to the difference between the given speed of the motor and the actual speed of the motor, and calculates the reference current i _d ^* of the d axis; uses the reference current of the d and q axes and the actual The current difference is improved by improving the UDE current controller to obtain the reference values of the d and q axis voltages respectively; transforming the obtained d and q axis voltage reference values into the voltage reference values in the two-phase rotating coordinate system to obtain the corresponding inverse The PWM pulse of the inverter is output by the inverter to obtain a three-phase voltage, which is used to drive the built-in permanent magnet synchronous motor; the cycle is repeated. The invention suppresses uncertain parameters and random disturbances in the system, reduces transient steady state torque fluctuations, and improves the performance of the built-in permanent magnet synchronous motor control system.

Description

Improved UDE current control method for built-in permanent magnet synchronous motor

technical field

The invention relates to a control method of a permanent magnet synchronous motor. In particular, it relates to an improved UDE current control method for an internal permanent magnet synchronous motor.

Background technique

In recent years, with the rapid development of electric vehicles, the interior permanent magnet synchronous machine (IPMSM) has attracted the attention of researchers and engineers due to its advantages of high power density, high torque density and high efficiency. . It has a simple structure and is beneficial to control; its reluctance effect can be used to improve the efficiency and load capacity of the motor. However. Electric vehicles are a system with complex working conditions. The entire motor system is susceptible to temperature-induced parameter changes, system random disturbances, and load conditions during operation. Therefore, higher performance requirements for interior permanent magnet synchronous motors Require.

In order to improve the operating efficiency of the motor, the interior permanent magnet synchronous motor usually adopts the maximum torque per ampere (MTPA) control to obtain the given d-axis current, so as to make full use of the reluctance torque; in the traditional control algorithm, the system The current loop uses the proportional integral (PI) vector control method to obtain d and q axis voltage given values through voltage decoupling. However, although the current loop structure using PI controller in the traditional control algorithm is simple to control and successfully applied in industrial control, a set of PI parameters is only applicable to a section of working conditions, and the desired control effect cannot be obtained in the entire control range. The current loop control performance of the traditional PI structure is difficult to obtain the desired effect under parameter changes, system random disturbances and complex load conditions, so a current control method with parameter uncertainty and random disturbance observation is introduced.

The parameter uncertainty and random disturbance observation method regards parameter changes and system random disturbance as unknown items, adopts a stable reference model to meet the expected tracking performance of the closed-loop system, and passes parameter uncertainty and system disturbance through a suitable The filter can then be used in the actual controller. However, the selection of the reference model and the tuning method of the parameters affect the control performance of the system.

Contents of the invention

The technical problem to be solved by the present invention is to provide an improved UDE current control method for a built-in permanent magnet synchronous motor that improves the current loop of a traditional PI controller.

The technical scheme adopted in the present invention is: a kind of built-in permanent magnet synchronous motor electric current control method that improves UDE, comprises the following steps:

1) In the current control cycle, the control system samples the actual motor speed n, the rotor position angle θ, the motor three-phase currents i _A , i _B and i _C , and the DC bus voltage u _dc , and uses the three-phase rotating coordinate system Transform to the two-phase static coordinate system to solve the d, q axis actual current i _d , i _q ;

2) According to the difference between the given motor speed n ^* and the motor’s actual speed n, the q-axis reference current i _q ^* is obtained through the proportional integral controller, and the d-axis reference current is calculated using the formula method in the maximum torque current ratio control method i _d ^* ;

3) Utilizing the difference between the reference current id ^* , i _q ^* of the _d , q axis and the actual current _id , i _q , by improving the current controller of UDE, the reference values u _d , u of the d, q axis voltage are respectively obtained _q ;

4) Transform the obtained d and q-axis voltage reference values u _d and u _q into voltage reference values u _α and u _β in the two-phase rotating coordinate system, and use the voltage space vector modulation method to obtain the corresponding PWM of the inverter Pulse, the three-phase voltage output by the inverter is used to drive the built-in permanent magnet synchronous motor;

5) Return to step 1) to repeat the loop.

The current controller of the improved UDE described in step 3) includes the following linear reference model:

In the formula, x _m (t)=[i _dm i _qm ] ^T is the current vector matrix in the reference model of d and q axes, c(t)=[i _d ^* i _q ^* ] ^T is the reference current of d and q axes Fixed vector matrix, A _m , B _m are coefficient matrices corresponding to x _m (t), c(t);

In order to ensure the stability of the control system, the coefficient matrices A _m and B _m of the linear reference model are expressed as follows:

In the formula, α and β are both positive real numbers, ensuring that the control system has two negative eigenvalues and satisfying the Lyapunov stability theory;

For parameter uncertainties and system random disturbances that appear in the control system, a first-order low-pass filter g _f (t) is used to compensate the disturbances in the system, and the frequency-domain form of the first-order low-pass filter g _f (t) G _f (s) is expressed as follows:

In the formula, γ=1/T, γ is the bandwidth of the selected first-order low-pass filter;

Uncertain parameters and system random disturbances can be observed through the first-order low-pass filter g _f (t) which is:

In the formula, "*" is the convolution operator, A and B are the coefficient matrices of x(t) and u(t), x(t)=[i _d i _q ] ^T is the actual current matrix of the d and q axes, u(t)=[u _d u _q ] ^T is the reference voltage matrix of the d and q axes, and is the input of the control system at the same time, f(t)=[f _d f _q ] ^T is the parameter uncertainty matrix of the d and q axes, D (t)=[D _d D _q ] ^T is the random perturbation matrix of the d and q axes, L _d and L _q are the inductances of the d and q axes, ψ _f is the rotor flux linkage, R _s is the stator resistance, is the known perturbation matrix of the d and q axes,

The control system input u(t) of the current controller of the improved UDE obtained by the linear reference model and the first-order low-pass filter is:

u(t)＝B ^-1 [A _m x _m (t)+B _m c(t)-Ax(t)-d ₀ (t)-f(t)-D(t)]

In the formula, B ^-1 is the inverse matrix of the coefficient matrix B;

Therefore, the control system input u(t) is expressed in the frequency domain as:

In the formula, U(s)=[U _d U _q ] ^T is the frequency domain form of the control system input on the d and q axes, E(s) is the frequency domain form of the current following error, I is the identity matrix, and the parameter K _P and K _I expressed as:

The adjustment method of the parameter _KI in described control system input u (t) is:

Add variable parameters γ _d1 and γ _q1 to the original intrinsic parameters γ _d0 and γ _q0 of parameter K _I to get As shown in the following formula:

The intrinsic parameters γ _d0 and γ _q0 are determined by α, β and γ; the d-axis variable parameter γ _d1 is obtained by the difference between the d-axis actual current and the reference current through a proportional controller; the q-axis variable parameter γ _q1 is the q The difference between the shaft reference current and the actual current is obtained through the proportional controller, as shown in the following formula:

The UDE-improved built-in permanent magnet synchronous motor current control method of the present invention is to improve the built-in permanent magnet synchronous motor current control method. It is proposed to apply the parameter uncertainty and random disturbance observation method to the built-in permanent magnet synchronous motor control system to improve the current loop of the traditional PI controller. By choosing an appropriate reference model and proposing a new parameter adjustment method, the output value of the desired voltage is obtained. The method of the present invention adopts an improved built-in permanent magnet synchronous motor current control method with uncertain parameters and random disturbance observation, the selected reference model ensures the stability of the system, and the first-order low-pass filter compensates the random disturbance of the system to realize The asymptotic following of the current. While the parameter uncertainty and the random disturbance in the system can be obviously suppressed, the torque fluctuation in the transient steady state can be reduced, thereby greatly improving the performance of the built-in permanent magnet synchronous motor control system.

Description of drawings

Fig. 1 is the main circuit structural diagram of the built-in permanent magnet synchronous motor current control method that improves UDE of the present invention;

Fig. 2 is the control structure diagram of the built-in permanent magnet synchronous motor current control method that improves UDE of the present invention;

Fig. 3 a is the principle diagram of the current control method of the built-in permanent magnet synchronous motor of the improved UDE of the present invention on the d axis;

Fig. 3b is a schematic diagram of the current control method of the built-in permanent magnet synchronous motor of the improved UDE of the present invention on the q axis;

Fig. 4 a is the schematic diagram of the adjustment method of parameter K ₁ in the d axis in the present invention;

Fig. 4 b is the schematic diagram of the adjustment method of parameter K ₁ in the q axis among the present invention;

Fig. 5 is a flow chart of the current control method of the interior permanent magnet synchronous motor for improving the UDE of the present invention.

Detailed ways

The current control method of the improved UDE of the present invention for an internal permanent magnet synchronous motor will be described in detail below in conjunction with the embodiments and the accompanying drawings.

The control system block diagram of the built-in permanent magnet synchronous motor current control method of the improved UDE of the present invention is shown in Figure 1, PI represents the proportional integral controller, and the actual speed n and position information θ of the motor are obtained by the incremental encoder, i _d , i _q is the actual current of the d and q axes obtained by the actual value detected by the current sensor and then changed from the three-phase rotating coordinate system to the two-phase static coordinate system. According to the proposed improved UDE current controller with parameter adjustment, its schematic diagram is shown in Figure 4.

The mathematical model of the built-in permanent magnet synchronous motor in the d-q axis synchronous rotating coordinate system can be expressed as:

In the formula, L _d , L _q are the inductances of d and q axes, ψ _f is the flux linkage of the rotor, P is the number of pole pairs of the motor, R _s is the stator resistance, id and i _q are the actual currents of the _d and q axes, ω _e is the electrical angular velocity of the rotor, and T _e is the electromagnetic torque.

The difference between the given speed n ^* and the actual speed n of the motor is obtained by the proportional-integral (PI) controller to obtain the q-axis reference current i _q ^* , and the d-axis reference current value is controlled by the maximum torque current ratio (MTPA), which can be obtained by the following formula inferred:

In the formula, i _q ^* is the given value of the q-axis reference current;

The mathematical model used by the improved UDE current controller is expressed as:

Among them: L _d and L _q are d and q axis inductances, ψ _f is rotor flux linkage, R _s is stator resistance, D _d and D _q are system random disturbances of d and q axes respectively; f _d and f _q are respectively are the resistance, inductance and flux linkage changes of the d and q axis motors, expressed as follows:

In order to realize the asymptotic following of the actual motor current and the given reference current, a stable reference model is used in the improved UDE current controller to satisfy the current following performance. Now select the following linear reference model:

In the formula, x _m (t)=[i _dm i _qm ] ^T is the current vector matrix in the reference model of d and q axes, c(t)=[i _d ^* i _q ^* ] ^T is the reference current of d and q axes Fixed vector matrix, A _m , B _m are coefficient matrices corresponding to x _m (t), c(t);

In order to ensure the stability of the system, the coefficient matrices A _m and B _m of the reference model are as follows:

In the formula, α and β are both positive real numbers, ensuring that the system has two negative eigenvalues and satisfying the Lyapunov stability theory.

The parameter uncertainty and random disturbance are added to the system through a filter with a suitable bandwidth; thus, the parameter uncertainty and random disturbance can be quickly estimated and compensated, and the robustness of the system is improved. The filter used in the system of the present invention is a first-order low-pass filter g _f (t), the disturbance in the compensation system, the frequency domain form G _f (s) of the first-order low-pass filter g _f (t) As follows:

Where, γ=1/T, γ is the bandwidth of the selected first-order low-pass filter.

Through the above-mentioned first-order low-pass filter g _f (t), the parameter uncertainty and system random disturbance can be observed which is:

In the formula, "*" is the convolution operator, A and B are the coefficient matrices of x(t) and u(t), x(t)=[i _d i _q ] ^T is the actual current matrix of the d and q axes, u(t)=[u _d u _q ] ^T is the reference voltage matrix of the d and q axes, and is the input of the control system at the same time, f(t)=[f _d f _q ] ^T , D(t)=[D _d D _q ] ^T , is the known perturbation matrix of the d and q axes,

The control system input u(t) of the current controller of the improved UDE obtained by the linear reference model and the first-order low-pass filter is:

u(t)=B ^-1 [A _m x _m (t)+B _m c(t)-Ax(t)-d ₀ (t)-f(t)-D(t)] (8)

In the formula, B ^-1 is the inverse matrix of the coefficient matrix B.

Therefore, the control system input u(t) is expressed in the frequency domain as:

In the formula, U(s)=[U _d U _q ] ^T is the frequency domain form of the control system input on the d and q axes, E(s) is the frequency domain form of the current following error, I is the identity matrix, and the parameter K _P and K _I expressed as:

However, the parameters in the current controller of the improved UDE are affected by different disturbances and correspond to different values. In order to realize parameter self-adaptation, the adjustment method of the parameter _KI in the input u(t) of the control system is:

Add variable parameters γ _d1 and γ _q1 to the original intrinsic parameters γ _d0 and γ _q0 of parameter K _I to get As shown in the following formula:

The intrinsic parameters γ _d0 and γ _q0 are determined by α, β and γ; the d-axis variable parameter γ _d1 is obtained by the difference between the d-axis actual current and the reference current through a proportional controller; the q-axis variable parameter γ _q1 is the q The difference between the shaft reference current and the actual current is obtained through the proportional controller, as shown in the following formula:

As shown in Figure 5, the current control method of the built-in permanent magnet synchronous motor of the improved UDE of the present invention specifically includes the following steps:

1) In the current control cycle, the control system samples the actual motor speed n, the rotor position angle θ, the motor three-phase currents i _A , i _B and i _C , and the DC bus voltage u _dc , and uses the three-phase rotating coordinate system Transform to the two-phase static coordinate system to solve the d, q axis actual current i _d , i _q ;

2) According to the difference between the given motor speed n ^* and the motor’s actual speed n, the q-axis reference current i _q ^* is obtained through a proportional-integral (PI) controller, and the formula method in the maximum torque current ratio (MTPA) control method is adopted Calculate the d-axis reference current i _d ^* ;

3) Utilizing the difference between the _d and q axis reference currents id ^* , i _q ^* and the actual currents id, i _q , the reference values u _d and u of the _d and q axis voltages are respectively obtained through the improved UDE current controller _q ; where,

The current controller of the improved UDE includes the following linear reference model:

In the formula, x _m (t)=[i _dm i _qm ] ^T is the current vector matrix in the reference model of d and q axes, c(t)=[i _d ^* i _q ^* ] ^T is the reference current of d and q axes Fixed vector matrix, A _m , B _m are coefficient matrices corresponding to x _m (t), c(t);

In order to ensure the stability of the control system, the coefficient matrices A _m and B _m of the linear reference model are expressed as follows:

In the formula, α and β are both positive real numbers, ensuring that the control system has two negative eigenvalues and satisfying the Lyapunov stability theory;

For parameter uncertainties and system random disturbances that appear in the control system, a first-order low-pass filter g _f (t) is used to compensate the disturbances in the system, and the frequency-domain form of the first-order low-pass filter g _f (t) G _f (s) is expressed as follows:

Where, γ=1/T, γ is the bandwidth of the selected first-order low-pass filter.

Uncertain parameters and system random disturbances can be observed through the first-order low-pass filter g _f (t) which is:

In the formula, "*" is the convolution operator, A and B are the coefficient matrices of x(t) and u(t), x(t)=[i _d i _q ] ^T is the actual current matrix of the d and q axes, u(t)=[u _d u _q ] ^T is the reference voltage matrix of the d and q axes, and is the input of the control system at the same time, f(t)=[f _d f _q ] ^T is the parameter uncertainty matrix of the d and q axes, D (t)=[D _d D _q ] ^T is the random perturbation matrix of the d and q axes, L _d and L _q are the inductances of the d and q axes, ψ _f is the rotor flux linkage, R _s is the stator resistance, is the known perturbation matrix of the d and q axes,

The control system input u(t) of the current controller of the improved UDE obtained by the linear reference model and the first-order low-pass filter is:

u(t)＝B ^-1 [A _m x _m (t)+B _m c(t)-Ax(t)-d ₀ (t)-f(t)-D(t)]

In the formula, B ^-1 is the inverse matrix of the coefficient matrix B;

Therefore, the control system input u(t) is expressed in the frequency domain as:

In the formula, U(s)=[U _d U _q ] ^T is the frequency domain form of the control system input on the d and q axes, E(s) is the frequency domain form of the current following error, I is the identity matrix, and the parameter K _P and K _I expressed as:

The adjustment method of the parameter _KI in described control system input u (t) is:

Add variable parameters γ _d1 and γ _q1 to the original intrinsic parameters γ _d0 and γ _q0 of parameter K _I to get As shown in the following formula:

The intrinsic parameters γ _d0 and γ _q0 are determined by α, β and γ; the d-axis variable parameter γ _d1 is obtained by the difference between the d-axis actual current and the reference current through a proportional controller; the q-axis variable parameter γ _q1 is the q The difference between the shaft reference current and the actual current is obtained through the proportional controller, as shown in the following formula:

4) Transform the obtained d and q-axis voltage reference values u _d , u _q into voltage reference values u _α , u _β in the two-phase rotating coordinate system, and use the voltage space vector modulation (SVPWM) method to obtain the corresponding inverter The PWM pulse of the inverter is output by the inverter to obtain the three-phase voltage, which is used to drive the built-in permanent magnet synchronous motor;

5) Return to step 1) to repeat the loop.

Claims (3)

1. A built-in permanent magnet synchronous motor current control method improving UDE, is characterized in that, comprises the steps: 1) In the current control cycle, the control system samples the actual motor speed n, the rotor position angle θ, the motor three-phase currents i _A , i _B and i _C , and the DC bus voltage u _dc , and uses the three-phase rotating coordinate system Transform to the two-phase static coordinate system to solve the d, q axis actual current i _d , i _q ; 2) According to the difference between the given motor speed n ^* and the motor’s actual speed n, the q-axis reference current i _q ^* is obtained through the proportional integral controller, and the d-axis reference current is calculated using the formula method in the maximum torque current ratio control method i _d ^* ; 3) Utilizing the difference between the reference current id ^* , i _q ^* of the _d , q axis and the actual current _id , i _q , by improving the current controller of UDE, the reference values u _d , u of the d, q axis voltage are respectively obtained _q ; 4) Transform the obtained d and q-axis voltage reference values u _d and u _q into voltage reference values u _α and u _β in the two-phase rotating coordinate system, and use the voltage space vector modulation method to obtain the corresponding PWM of the inverter Pulse, the three-phase voltage output by the inverter is used to drive the built-in permanent magnet synchronous motor; 5) Return to step 1) to repeat the loop. 2. the built-in permanent magnet synchronous motor current control method of improving UDE according to claim 1, is characterized in that, the current controller of improving UDE described in step 3) comprises following linear reference model: In the formula, x _m (t)=[i _dm i _qm ] ^T is the current vector matrix in the reference model of d and q axes, c(t)=[i _d ^* i _q ^* ] ^T is the reference current of d and q axes Fixed vector matrix, A _m , B _m are coefficient matrices corresponding to x _m (t), c(t); In order to ensure the stability of the control system, the coefficient matrices A _m and B _m of the linear reference model are expressed as follows: In the formula, α and β are both positive real numbers, ensuring that the control system has two negative eigenvalues and satisfying the Lyapunov stability theory; For parameter uncertainties and system random disturbances that appear in the control system, a first-order low-pass filter g _f (t) is used to compensate the disturbances in the system, and the frequency-domain form of the first-order low-pass filter g _f (t) G _f (s) is expressed as follows: In the formula, γ=1/T, γ is the bandwidth of the selected first-order low-pass filter; Uncertain parameters and system random disturbances can be observed through the first-order low-pass filter g _f (t) which is: In the formula, "*" is the convolution operator, A and B are the coefficient matrices of x(t) and u(t), x(t)=[i _d i _q ] ^T is the actual current matrix of the d and q axes, u(t)=[u _d u _q ] ^T is the reference voltage matrix of the d and q axes, and is the input of the control system at the same time, f(t)=[f _d f _q ] ^T is the parameter uncertainty matrix of the d and q axes, D (t)=[D _d D _q ] ^T is the random perturbation matrix of the d and q axes, L _d and L _q are the inductances of the d and q axes, ψ _f is the rotor flux linkage, R _s is the stator resistance, is the known perturbation matrix of the d and q axes, The control system input u(t) of the current controller of the improved UDE obtained by the linear reference model and the first-order low-pass filter is: u(t)＝B ^-1 [A _m x _m (t)+B _m c(t)-Ax(t)-d ₀ (t)-f(t)-D(t)] In the formula, B ^-1 is the inverse matrix of the coefficient matrix B; Therefore, the control system input u(t) is expressed in the frequency domain as: In the formula, U(s)=[U _d U _q ] ^T is the frequency domain form of the control system input on the d and q axes, E(s) is the frequency domain form of the current following error, I is the identity matrix, and the parameter K _P and K _I expressed as: 3. the built-in permanent magnet synchronous motor current control method of improving _UDE according to claim 2, is characterized in that, the adjustment method of the parameter K in the described control system input u (t) is: Add variable parameters γ _d1 and γ _q1 to the original intrinsic parameters γ _d0 and γ _q0 of parameter K _I to get As shown in the following formula: The intrinsic parameters γ _d0 and γ _q0 are determined by α, β and γ; the d-axis variable parameter γ _d1 is obtained by the difference between the d-axis actual current and the reference current through a proportional controller; the q-axis variable parameter γ _q1 is the q The difference between the shaft reference current and the actual current is obtained through the proportional controller, as shown in the following formula: