Permanent magnet synchronous motor sliding mode control method and control device based on adaptive variable exponential reaching law, and permanent magnet synchronous motor

Abstract

A permanent magnet synchronous motor sliding mode control method based on a self-adaptive variable exponential reaching law comprises the steps that the actual rotating speed of a permanent magnet synchronous motor is obtained, and the actual rotating speed and the given rotating speed are subtracted to obtain the rotating speed deviation; the rotating speed deviation is input into a sliding mode speed controller constructed based on an adaptive variable exponential reaching law for calculation, and a q-axis current given value is obtained; and controlling the permanent magnet synchronous motor based on the q-axis current given value. According to the permanent magnet synchronous motor sliding mode control method and device based on the self-adaptive variable exponential reaching law and the permanent magnet synchronous motor, buffeting can be suppressed while the time for the system state to reach the sliding mode surface is shortened, and the control performance of the permanent magnet synchronous motor is improved.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, specifically to a sliding mode control method, control device, and permanent magnet synchronous motor based on an adaptive variable exponential approach law. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have been widely used in new energy vehicles, CNC machine tools, and other fields due to their advantages such as simple structure, high power density, high efficiency, and wide speed range. Currently, the dual-closed-loop PI control strategy based on an outer speed loop and an inner current loop is the mainstream vector control scheme for this type of motor. However, it should be noted that PMSMs are complex control objects with multivariable, strongly coupled, and nonlinear characteristics. This makes traditional PI control prone to a decrease in control accuracy when faced with external disturbances or internal parameter perturbations.

[0003] To improve the control accuracy and robustness of the speed loop, scholars both domestically and internationally have proposed various nonlinear control methods. Among them, sliding mode variable structure control (SMC), as a discontinuous nonlinear control strategy, has shown significant advantages in the field of permanent magnet synchronous motor control due to its outstanding characteristics such as insensitivity to changes in system parameters and good dynamic performance.

[0004] However, the chattering characteristics in sliding mode variable structures can reduce the performance of sliding mode control to some extent, and existing technologies cannot effectively solve the chattering problem. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a sliding mode control method, control device, and permanent magnet synchronous motor based on an adaptive variable exponential approach law. This method can suppress chattering while shortening the time it takes for the system state to reach the sliding surface, thereby improving the control performance of the permanent magnet synchronous motor.

[0006] To achieve the above objectives, the specific solution adopted by this invention is as follows: a sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law, comprising: Obtain the actual speed ω of the permanent magnet synchronous motor m And with a given rotational speed ω ref The difference is used to obtain the speed deviation e. ω ; Speed ​​deviation e ω The input is fed into a sliding mode speed controller based on an adaptive variable exponential reaching law for calculation, to obtain the q-axis current setpoint i. qref ; The sliding mode speed controller is: s = cx1 + x2; in, Actual rotational speed rate of change, For a given rotational speed ω ref The rate of change of , c is the sliding surface parameter, S is the sliding surface, sgn(·) is the sign function, ε is the action factor of the variable exponential term, δ1 and δ2 are the lower and upper limits of the action region of the variable exponential term, x1 is the rotational speed error, x2 is the rate of change of the rotational speed error, ζ, k 0、 k1, k2, b, d, n, and m are any positive numbers, and a and λ are positive numbers whose values ​​are in the range (0,1). Based on the q-axis current given value i qref Control the permanent magnet synchronous motor.

[0007] As a further optimization of the aforementioned sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law, the method further includes: Obtain the actual value of the q-axis current i of the permanent magnet synchronous motor q and the actual value of d-axis current i d ; Based on the q-axis current given value i qref Compared with the actual value of the q-axis current i q Calculate the q-axis current error e iq And based on the d-axis current given value i dref Compared with the actual value of d-axis current i d Calculate the d-axis current error e id ; Based on q-axis current error e iq and d-axis current error e id Generate α-axis control voltage u α and β-axis control voltage u β ; Based on α-axis control voltage u α and β-axis control voltage u β Generate a switch signal; The switching signal controls the on / off state of the bridge arms in a three-phase inverter.

[0008] As a further optimization of the aforementioned sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law: Obtain the actual value i of the q-axis current of the permanent magnet synchronous motor. q and the actual value of d-axis current i d The methods include: Obtain the three-phase current i of the permanent magnet synchronous motor a i b and i c ; For three-phase current i a i b and i c The α-axis current i is obtained by performing the Clark transformation. α and β-axis current i β ; For the α-axis current i α and β-axis current i β Performing the Park transformation yields the actual q-axis current value i. q and the actual value of d-axis current i d .

[0009] As a further optimization of the aforementioned sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law: based on the q-axis current error e iq and d-axis current error e id Generate α-axis control voltage u α and β-axis control voltage u β The methods include: Use a q-axis PI current loop controller to control the q-axis current error e. iq The q-axis reference voltage u is obtained through processing. q And a d-axis PI current loop controller is used to control the d-axis current error e. id The d-axis reference voltage u is obtained through processing. d ; For the q-axis reference voltage u q and d-axis reference voltage u d Perform the inverse Park transform to obtain the α-axis control voltage u α and β-axis control voltage u β .

[0010] As a further optimization of the aforementioned sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law: based on the α-axis control voltage u α and β-axis control voltage u β The method for generating the switching signal is as follows: Control the α-axis voltage u α and β-axis control voltage u β SVPWM modulation is performed to obtain the switching signal.

[0011] As a further optimization of the aforementioned sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law: the q-axis current setpoint i qref for: Where, p n ψ is the number of pole pairs of a permanent magnet synchronous motor. f Let J be the flux linkage of the permanent magnet, J be the moment of inertia of the permanent magnet synchronous motor, and D(t) be the external disturbance.

[0012] A control device is used to implement the above-described sliding mode control method for a permanent magnet synchronous motor based on an adaptive variable exponential reaching law. The device includes: An encoder is used to obtain the actual speed ω of a permanent magnet synchronous motor. m ; The upper-level control module is used to control the actual rotational speed ω. m With a given rotational speed ω ref The difference is used to obtain the speed deviation e. ω And a sliding mode speed controller and speed deviation e based on an adaptive variable exponential reaching law. ω The q-axis current setpoint i is obtained through calculation. qref ; The lower-level control module is used to control the q-axis current based on the given value i. qref Control the permanent magnet synchronous motor.

[0013] The permanent magnet synchronous motor includes a motor body, a three-phase inverter for driving the motor body, and the aforementioned control device for controlling the three-phase inverter.

[0014] Beneficial Effects: This invention employs a sliding mode speed controller based on an adaptive variable exponential reaching law. By utilizing the interplay of variable exponential terms, adaptive switching terms, and double power terms, it shortens the time for the system state to reach the sliding surface while suppressing chattering, thus improving the control performance of the permanent magnet synchronous motor. Compared to traditional reaching laws, the control method of this invention has a faster response speed and less chattering. Attached Figure Description

[0015] Figure 1 This is a control block diagram of an embodiment of the control method of the present invention; Figure 2 This is a schematic diagram comparing different switching functions in an embodiment of the control method of the present invention; Figure 3 This is a schematic diagram of the sudden load speed response of a speed regulation system based on the control method of the present invention; Figure 4 A schematic diagram of the sudden load speed response of a speed control system based on traditional exponential reaching law sliding mode variable structure control; Figure 5 This is a schematic diagram of the sudden load torque response of a speed regulation system based on the control method of the present invention; Figure 6 This is a schematic diagram of the sudden load torque response of a speed control system based on traditional exponential reaching law sliding mode variable structure control. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, a sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law is presented, comprising S1 to S3.

[0018] S1. Obtain the actual speed ω of the permanent magnet synchronous motor. m And with a given rotational speed ω ref The difference is used to obtain the speed deviation e. ω .

[0019] S2, reduce the speed deviation e ω The input is fed into a sliding mode speed controller based on an adaptive variable exponential reaching law for calculation, to obtain the q-axis current setpoint i. qref .

[0020] In S2, the sliding mode speed controller is: s = cx1 + x2; in, Actual rotational speed rate of change, For a given rotational speed ω ref The rate of change of , c is the sliding surface parameter, s is the sliding surface, sgn(·) is the sign function, ε is the variable exponential term action factor, δ1 and δ2 are the lower and upper limits of the variable exponential term action area, x1 is the rotational speed error, x2 is the rate of change of rotational speed error, ζ, k0, k1, k2, b, d, n and m are arbitrary positive numbers, and a and λ are positive numbers with a range of (0,1).

[0021] Based on the above sliding mode speed controller, the q-axis current setpoint i is calculated. qref for: Where, p n ψ is the number of pole pairs of a permanent magnet synchronous motor. f Let J be the flux linkage of the permanent magnet, J be the moment of inertia of the permanent magnet synchronous motor, and D(t) be the external disturbance.

[0022] S3, Based on the q-axis current setpoint i qref Control the permanent magnet synchronous motor.

[0023] This invention employs a sliding mode speed controller based on an adaptive variable exponential reaching law. By utilizing the interplay of variable exponential terms, adaptive switching terms, and double power terms, it shortens the time for the system state to reach the sliding surface while suppressing chattering, thereby improving the control performance of the permanent magnet synchronous motor. Compared to traditional reaching laws, the control method of this invention has a faster response speed and less chattering.

[0024] Furthermore, the method of the present invention also includes steps S4 to S8.

[0025] S4. Obtain the actual value i of the q-axis current of the permanent magnet synchronous motor. q and the actual value of d-axis current i d More specifically, to obtain the actual value i of the q-axis current of the permanent magnet synchronous motor. q and the actual value of d-axis current i d The methods include S41 to S43.

[0026] S41. Obtain the three-phase current i of the permanent magnet synchronous motor. a i b and i c .

[0027] S42, Regarding the three-phase current i a i b and i c The α-axis current i is obtained by performing the Clark transformation. α and β-axis current i β .

[0028] S43, regarding the α-axis current i α and β-axis current i β Performing the Park transformation yields the actual q-axis current value i. q and the actual value of d-axis current i d .

[0029] S5, Based on the q-axis current setpoint iq ref Compared with the actual value of the q-axis current i q Calculate the q-axis current error e iq And based on the d-axis current given value i dref Compared with the actual value of d-axis current i d Calculate the d-axis current error e id .

[0030] S6, Based on q-axis current error e iq and d-axis current error e id Generate α-axis control voltage u α and β-axis control voltage u β More specifically, based on the q-axis current error e iq and d-axis current error e id Generate α-axis control voltage uα and β-axis control voltage u β The methods include S61 to S62.

[0031] S61. Use a q-axis PI current loop controller to control the q-axis current error e. iq The q-axis reference voltage u is obtained through processing. q And a d-axis PI current loop controller is used to control the d-axis current error e. id The d-axis reference voltage u is obtained through processing. d .

[0032] S62, regarding the q-axis reference voltage u q and d-axis reference voltage u d Perform the inverse Park transform to obtain the α-axis control voltage u α and β-axis control voltage u β .

[0033] S7 is based on α-axis control voltage u α and β-axis control voltage u β Generate a switching signal. More specifically, based on the α-axis control voltage u. α and β-axis control voltage u β The method for generating the switching signal is as follows: Control the α-axis voltage u α and β-axis control voltage u β SVPWM modulation is performed to obtain the switching signal.

[0034] S8. Controlling the on / off state of the bridge arms in a three-phase inverter based on switching signals.

[0035] Figure 2 This is a schematic diagram of the switching function in the reaching law of this embodiment. Figure 2 It can be seen that after entering the boundary layer (-λ,λ), the switching function in the sliding mode speed controller of the present invention is smoother and the transition is more gradual than the sign function sgn(·), which reduces the high-frequency chattering of the system. Compared with the commonly used sigmoid(·) function in the field, it has a faster approach speed and takes into account both chattering suppression and convergence speed.

[0036] To verify the rationality and effectiveness of this invention, a simulation model was built in Simulink for verification. The PMSM parameters used in the simulation are shown in Table 1.

[0037] Table 1 System Simulation Parameters

[0038] The simulation conditions are no-load start-up, given speed of 300 rpm, load torque suddenly increased to 5 N·m at 0.2s, and load suddenly decreased to 0 N·m at t=0.3s. The simulation results are observed, including speed response and torque change. The simulation results show that the sliding mode controller based on the adaptive variable exponential approach law has a faster adjustment speed and smaller overshoot.

[0039] During no-load start-up, the overshoot of traditional exponential reaching law control is 47.7 rpm, reaching steady state at 0.0780 s. The speed overshoot of the system based on adaptive variable exponential reaching law control is approximately 0, reaching steady state at 0.0066 s. Compared with exponential reaching law control, the overshoot is reduced by 47.7 rpm, and the time to recover to steady state is shortened by 0.0714 s. Therefore, compared with the permanent magnet synchronous motor speed control system based on traditional exponential reaching law control, the speed control system based on sliding mode reaching law control described in this invention reaches stable operation in a shorter time during no-load start-up and can achieve a stable state without overshoot. In contrast, the speed control system based on traditional exponential reaching law control has overshoot during start-up. It can be seen that the adaptive variable exponential reaching law control has better performance during no-load start-up.

[0040] Figure 3 This is a schematic diagram of the sudden load speed response of the speed regulation system based on the sliding mode variable structure control of the present invention. Figure 4 This is a schematic diagram of a speed control system based on traditional exponential reaching law control. Figure 5 This is a schematic diagram of the sudden load torque response of the speed control system based on the sliding mode variable structure control of the present invention, as shown below. Figure 6 The diagram illustrates the torque response to sudden load changes based on traditional exponential reaching law control. It shows that when the load is suddenly increased or decreased, the traditional exponential reaching law is more sensitive to changes in load torque, resulting in a longer dynamic recovery time and larger speed fluctuations caused by sudden load changes. During a sudden load increase, the speed drops by approximately 22 rpm, and a longer recovery time is required to return to the original steady state. Using the sliding mode control strategy described in this invention, the torque dynamic performance is better when the load torque changes abruptly. During a sudden load increase, the speed drops by only about 7 rpm, which is 15 rpm less than the speed drop caused by the exponential reaching law control. Furthermore, the steady-state performance is also superior to that of the traditional exponential reaching law.

[0041] The present invention further provides a control device for implementing the above-mentioned sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential approach law. The device includes an encoder, a host control module, and a slave control module.

[0042] An encoder is used to obtain the actual speed ω of a permanent magnet synchronous motor. m .

[0043] The upper-level control module is used to control the actual rotational speed ω. m With a given rotational speed ω refThe difference is used to obtain the speed deviation e. ω And a sliding mode speed controller and speed deviation e based on an adaptive variable exponential reaching law. ω The q-axis current setpoint i is obtained through calculation. qref .

[0044] The lower-level control module is used to control the q-axis current based on the given value i. qref Control the permanent magnet synchronous motor.

[0045] The present invention also provides a permanent magnet synchronous motor, including a motor body, a three-phase inverter for driving the motor body, and the aforementioned control device for controlling the three-phase inverter.

[0046] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law, characterized in that, include: Obtain the actual speed ω of the permanent magnet synchronous motor m And with a given rotational speed ω ref The difference is used to obtain the speed deviation e. ω ; Speed ​​deviation e ω The input is fed into a sliding mode speed controller based on an adaptive variable exponential reaching law for calculation, to obtain the q-axis current setpoint i. qref ; The sliding mode speed controller is: s = cx1 + x2; in, Actual rotational speed rate of change, For a given rotational speed ω ref The rate of change of , c is the sliding surface parameter, s is the sliding surface, sgn(·) is the sign function, ε is the action factor of the variable exponential term, δ1 and δ2 are the lower and upper limits of the action area of ​​the variable exponential term, x1 is the rotational speed error, x2 is the rate of change of the rotational speed error, ζ, k0, k1, k2, b, d, n and m are arbitrary positive numbers, and a and λ are positive numbers with a range of (0,1); Based on the q-axis current given value i qref Control the permanent magnet synchronous motor.

2. The sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law as described in claim 1, characterized in that, The method further includes: Obtain the actual value of the q-axis current i of the permanent magnet synchronous motor q and the actual value of d-axis current i d ; Based on the q-axis current given value i qref Compared with the actual value of the q-axis current i q Calculate the q-axis current error e iq And based on the d-axis current given value i dref Compared with the actual value of d-axis current i d Calculate the d-axis current error e id ; Based on q-axis current error e iq and d-axis current error e id Generate α-axis control voltage u α and β-axis control voltage u β ; Based on α-axis control voltage u α and β-axis control voltage u β Generate a switch signal; The switching signal controls the on / off state of the bridge arms in a three-phase inverter.

3. The sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law as described in claim 2, characterized in that, Obtain the actual value of the q-axis current i of the permanent magnet synchronous motor q and the actual value of d-axis current i d The methods include: Obtain the three-phase current i of the permanent magnet synchronous motor a i b and i c ; For three-phase current i a i b and i c The α-axis current i is obtained by performing the Clark transformation. α and β-axis current i β For the α-axis current i α and β-axis current i β Performing the Park transformation yields the actual q-axis current value i. q and the actual value of d-axis current i d .

4. The sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law as described in claim 2, characterized in that, Based on q-axis current error e iq and d-axis current error e id Generate α-axis control voltage u α and β-axis control voltage u β The methods include: Use a q-axis PI current loop controller to control the q-axis current error e. iq The q-axis reference voltage u is obtained through processing. q And a d-axis PI current loop controller is used to control the d-axis current error e. id The d-axis reference voltage u is obtained through processing. d ; For the q-axis reference voltage u q and d-axis reference voltage u d Perform the inverse Park transform to obtain the α-axis control voltage u α and β-axis control voltage u β .

5. The sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law as described in claim 2, characterized in that, Based on α-axis control voltage u α and β-axis control voltage u β The method for generating the switching signal is as follows: Control the α-axis voltage u α and β-axis control voltage u β SVPWM modulation is performed to obtain the switching signal.

6. The sliding mode control method for permanent magnet synchronous motors based on an adaptive variable exponential reaching law as described in claim 1, characterized in that, The q-axis current given value i qref for: Where, p n ψ is the number of pole pairs of a permanent magnet synchronous motor. f Let J be the flux linkage of the permanent magnet, J be the moment of inertia of the permanent magnet synchronous motor, and D(t) be the external disturbance.

7. A control device, characterized in that, The apparatus for implementing a sliding mode control method for a permanent magnet synchronous motor based on an adaptive variable exponential reaching law as described in any one of claims 1-6 includes: An encoder is used to obtain the actual speed ω of a permanent magnet synchronous motor. m ; The upper-level control module is used to control the actual rotational speed ω. m With a given rotational speed ω ref The difference is used to obtain the speed deviation e. ω And a sliding mode speed controller and speed deviation e based on an adaptive variable exponential reaching law. ω The q-axis current setpoint i is obtained through calculation. qref ; The lower-level control module is used to control the q-axis current based on the given value i. qref Control the permanent magnet synchronous motor.

8. A permanent magnet synchronous motor, characterized in that, It includes a motor body, a three-phase inverter for driving the motor body, and a control device as described in claim 8 for controlling the three-phase inverter.

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