CN104038133B - A kind of permanent magnetic linear synchronous motor shifting sliding surface sliding mode positioning control method - Google Patents

Abstract

The invention relates to a method for controlling the position of a permanent magnet synchronous linear motor translation sliding plane sliding mode. A sliding mode control system for a translational sliding plane is provided to realize high-precision position control of a permanent magnet synchronous linear motor, so that the system has good tracking performance and good robustness and anti-interference ability. In the present invention, by adding a sliding mode variable structure controller in the position control outer loop, the position difference becomes a state variable, which is controlled by the controller to enter the sliding plane sliding, so that the position tracking is stable and has nothing to do with the parameter changes of the motor and external disturbances, directly satisfying the The purpose of position tracking and anti-interference of permanent magnet synchronous linear motor; compared with the traditional sliding plane, the translational sliding plane designed in this paper can make the permanent magnet synchronous linear motor have better robustness and anti-interference while maintaining fast tracking response Capability; the system has simple structure and high stability, and can be applied in engineering practice.

Description

A sliding mode position control method for translational sliding plane of permanent magnet synchronous linear motor

technical field

The invention relates to a method for controlling the position of a permanent magnet synchronous linear motor translation sliding plane sliding mode.

Background technique

Permanent magnet synchronous linear motor is a mechanical device that can directly convert electrical energy into mechanical energy without any intermediate conversion mechanism. It has the advantages of simple structure, high precision, high speed and low maintenance. It is precisely because of the lack of intermediate buffer links that disturbances such as thrust fluctuations and friction directly act on permanent magnet synchronous linear motors. Compared with rotary motors, they are more sensitive to load disturbances and changes in the internal structure parameters of the motor, and the quality of interference suppression The requirements are higher and the degree of nonlinearity is stronger.

The sliding mode variable structure control method is suitable for nonlinear systems with uncertain parameters. Through a certain control strategy, the control quantity is continuously switched, that is, the structure of the system is constantly changing, and the system is forced to slide into the preset sliding mode surface in a targeted manner. After the system enters the sliding mode state, the stability and dynamic quality of the system only depend on the sliding surface and the parameters of the sliding surface. Since the sliding mode can be designed and has nothing to do with system parameter changes and external disturbances, it has strong robustness and high reliability. Some scholars have applied a new type of reaching law control law to motor control. This method not only improves the response speed of the system, but also effectively reduces the chattering. Some scholars have proposed a method of adding an observer to the system and using a neural network to learn the upper bound of the estimated error. This method improves the accuracy of the system, reduces the tracking error, and makes the system have good rapidity and stability. However, due to The addition of the observer makes the system more complex, and the introduction of the neural network leads to a large amount of calculation and is not easy to implement. Due to the fixed sliding plane of these conventional motor sliding mode control systems, when the system has a large disturbance or a large parameter perturbation, the system state quantity cannot converge quickly in the process of tending to the sliding plane, so the adjustment speed of the system is slow, and the system The anti-interference ability and robustness are poor. Compared with conventional sliding mode control, translational sliding plane control has better robustness and anti-interference ability, and its structure is simple and easy to realize in engineering. So far, the sliding mode control method of translational sliding plane has not been applied in permanent magnet synchronous linear motors.

Contents of the invention

The purpose of the present invention is to provide a sliding mode position control method for a translational sliding plane of a permanent magnet synchronous linear motor, so that the system has good tracking performance and good robustness and anti-interference ability.

In order to achieve the above object, the technical solution of the present invention is: a method for controlling the position of a permanent magnet synchronous linear motor translational sliding plane sliding mode, providing a translational sliding plane sliding mode control system to realize the position control of the permanent magnet synchronous linear motor, the system It includes a main circuit and a control circuit, wherein the main circuit includes an AC power supply, a rectifier and a three-phase inverter for power supply of the entire system; the control circuit includes a current control inner loop and a position control outer loop, and the A sliding mode variable structure controller is provided in the position control outer loop, and the sliding mode variable structure controller takes the displacement difference e between the mover displacement d and the given displacement dm as the input signal in the position control outer loop, and outputs Current command control signal i _q ; the specific steps are as follows,

Step S1: Design the sliding surface:

The mechanical dynamic equation of the known permanent magnet synchronous linear motor is:

After simplification:

Among them, D is the viscous damping coefficient, M is the mass of the mover, K _f is the thrust constant, and F _L is the load thrust;

make , , ,

but

When the parameters are perturbed,

in,

In the formula, , , represent the perturbations of system parameters A, B, and C, respectively;

The conventional sliding plane is designed as , and design a translational sliding plane on the basis of the conventional sliding plane, so that ;when When , the sliding plane moves down; when When , the sliding plane moves up; when , the translational sliding plane is equivalent to a conventional sliding plane; let ,in , floor(*) represents the rounding down function, e represents the displacement difference, Indicates that the control amount is When , the displacement difference of the system, c and to set parameters;

Step S2: Proof of generalized sliding mode conditions:

Pick

Construct the Lyapunov function, , then there is

Therefore, when hour, When , the system is stable; among them, is the upper bound of the uncertainty factor H, and k is the setting parameter;

Step S3: Design the control law:

According to the designed control law of translational sliding plane design:

Step S4: Set u as the expected given value of the q-axis current of the current regulator, set the expected given value of the d-axis current of the current regulator to 0, and perform SVPWM modulation on the output of the current regulator to obtain the actual The drive signal for the PWM inverter at the stator end of the linear motor.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the present invention, by adding a sliding mode variable structure controller in the position control outer loop, the position difference becomes a state variable, which is controlled by the controller to enter the sliding plane sliding, so that the position tracking is stable and has nothing to do with the parameter changes of the motor and external disturbances. Directly meet the purpose of permanent magnet synchronous linear motor position tracking and anti-interference;

2. Compared with the traditional sliding plane, the translational sliding plane designed in this paper can make the permanent magnet synchronous linear motor have better robustness and anti-interference ability while maintaining fast tracking response;

3. The system of the present invention has simple structure and high stability, and can be applied in engineering practice.

Description of drawings

Fig. 1 is a block diagram of a sliding mode control system for a translational sliding plane of the present invention.

detailed description

The technical solution of the present invention will be specifically described below in conjunction with the accompanying drawings.

A method for controlling the position of a permanent magnet synchronous linear motor translational sliding plane sliding mode provides a translational sliding plane sliding mode control system to realize the position control of a permanent magnet synchronous linear motor. The system includes a main circuit and a control circuit, wherein, The main circuit includes an AC power supply, a rectifier and a three-phase inverter for power supply of the entire system; the control circuit includes a current control inner loop and a position control outer loop, and the position control outer loop is provided with a sliding mode A variable structure controller, the sliding mode variable structure controller is in the position control outer loop, taking the displacement difference e between the mover displacement d and the given displacement dm as the input signal, and outputting the current command control signal i _q ; specifically including Proceed as follows,

Step S1: Design the sliding surface:

The mechanical dynamic equation of the known permanent magnet synchronous linear motor is:

After simplification:

Among them, D is the viscous damping coefficient, M is the mass of the mover, K _f is the thrust constant, and F _L is the load thrust;

make , , ,

but

When the parameters are perturbed,

in,

In the formula, , , represent the perturbations of system parameters A, B, and C, respectively;

The conventional sliding plane is designed as , and design a translational sliding plane on the basis of the conventional sliding plane, so that ;when When , the sliding plane moves down; when When , the sliding plane moves up; when , the translational sliding plane is equivalent to a conventional sliding plane; let ,in , floor(*) represents the rounding down function, e represents the displacement difference, Indicates that the control amount is When , the displacement difference of the system, c and to set parameters;

Step S2: Proof of generalized sliding mode conditions:

Pick

Construct the Lyapunov function, , then there is

Therefore, when hour, When , the system is stable; among them, is the upper bound of the uncertainty factor H, and k is the setting parameter;

Step S3: Design the control law:

According to the designed control law of translational sliding plane design:

Step S4: Set u as the expected given value of the q-axis current of the current regulator, set the expected given value of the d-axis current of the current regulator to 0, and perform SVPWM modulation on the output of the current regulator to obtain the actual The drive signal for the PWM inverter at the stator end of the linear motor.

As shown in Figure 1, the mature vector control technology is used for design. Firstly, the stator three-phase currents _ia , _ib , and _ic of the permanent magnet synchronous linear motor are detected by the current sensor, and the three-phase stator currents are transformed by Clarke. , get the current in the two-phase stationary coordinate system , after the park transformation, the current in the two-phase stationary coordinate system Transformed into the current _id and i _q in the two-phase rotating coordinate system, _id and i _q are the feedback current of the current loop, and the expected current for the permanent magnet synchronous linear motor is given as , p is the number of pole pairs, ψ is the rotor excitation flux linkage, T _e ^* is the electromagnetic torque setting of the motor, in order to improve the power factor of the generator and reduce the torque ripple, set the d-axis current setting as i _d ^* = 0, the figure shows the q-axis current control block diagram, the d-axis current control block diagram and the tuning machine parameters are the same as the q-axis; the transfer function of the q-axis current loop control object is , where L is the stator inductance, and R is the stator winding resistance. Considering that the current loop needs a faster tracking capability, the PI regulator is used to set the regulator parameters according to a typical type 1 system. The transfer function of the PI regulator is , where , , K _PWM is a small gain such as the bridge circuit of the PWM rectifier, when using SVPWM modulation, K _PWM =1.

The above are the preferred embodiments of the present invention, and all changes made according to the technical solution of the present invention, when the functional effect produced does not exceed the scope of the technical solution of the present invention, all belong to the protection scope of the present invention.

Claims (1)

1. A method for position control of a permanent magnet synchronous linear motor translational sliding plane sliding mode, characterized in that: a translational sliding plane sliding mode control system is provided to realize the position control of a permanent magnet synchronous linear motor, and the system includes a main circuit and a control circuit , wherein, the main circuit includes an AC power supply, a rectifier and a three-phase inverter for the power supply of the entire system; the control circuit includes a current control inner loop and a position control outer loop, and the position control outer loop is set There is a sliding mode variable structure controller, the sliding mode variable structure controller is in the position control outer loop, taking the displacement difference e between the mover displacement d and the given displacement dm as the input signal, and outputting the current command control signal i _q ; The specific steps are as follows, Step S1: Design the sliding surface: The mechanical dynamic equation of the known permanent magnet synchronous linear motor is: After simplification: Among them, D is the viscous damping coefficient, M is the mass of the mover, K _f is the thrust constant, and F _L is the load thrust; make , , , but When the parameters are perturbed, in, In the formula, , , represent the perturbations of system parameters A, B, and C, respectively; The conventional sliding plane is designed as , and design a translational sliding plane on the basis of the conventional sliding plane, so that ;when When , the sliding plane moves down; when When , the sliding plane moves up; when , the translational sliding plane is equivalent to a conventional sliding plane; let ,in , floor(*) represents the rounding down function, e represents the displacement difference, Indicates that the control amount is When , the displacement difference of the system, c and to set parameters; Step S2: Proof of generalized sliding mode conditions: Pick Construct the Lyapunov function, , then there is Therefore, when hour, When , the system is stable; among them, is the upper bound of the uncertainty factor H, and k is the setting parameter; Step S3: Design the control law: According to the designed control law of translational sliding plane design: Step S4: Set u as the expected given value of the q-axis current of the current regulator, set the expected given value of the d-axis current of the current regulator to 0, and perform SVPWM modulation on the output of the current regulator to obtain the actual The drive signal for the PWM inverter at the stator end of the linear motor.