PMSM Vector Control Based On Sliding Mode Variable Structure

With the high demand of society,the development of power electronic technology,and the improvement of integration,the application of permanent magnet synchronous motors is becoming more and more extensive.Subsequently,the research on the AC motor speed regulation system is favored by scholars and has a broad space for development.The sliding mode variable structure control strategy has the advantages of strong robustness and fast response,but it is prone to chattering.The permanent magnet synchronous motor vector control system using sliding mode control has the characteristics of being insensitive to parameters and external disturbances.In order to improve the steady-state performance of the system,it is necessary to minimize the chattering generated by the sliding mode control strategy.In the practical application of vector control systems,mechanical sensors are often used to obtain the rotor position information of the motor,but the installation of mechanical sensors will bring some problems.This article uses speed sensorless control technology to estimate the speed and rotor position information.With the surface-mounted permanent magnet synchronous motor as the research object,sliding mode control strategy to design the speed loop controller and the speed sensorless part to form a complete vector control system is adopted in this article.The specific research is as follows.1.The research status of permanent magnet synchronous motor control strategy and speed sensorless is analyzed.An equivalent mathematical model is built based on the structure of the permanent magnet synchronous motor,and the mathematical equations of the permanent magnet synchronous motor in different coordinate systems are explained.Through Park transformation and Clark transformation,the mathematical model of permanent magnet synchronous motor can be transformed,and the coupling items in the three-phase static coordinate system can be decoupled.This transformation provides convenience for further analysis.Next,the principle of SVPWM is described,and the simulation model of SVPWM module is built according to the principle.2.Design the speed loop controller,using the global fast terminal sliding mode surface,combining linear sliding mode and fast terminal mode,so that the system can converge from any initial state to an equilibrium state in a finite time.Designing a continuous control law without switching items can weaken chattering to a certain extent and improve system robustness.Through MATLAB/SIMULINK simulation,the designed global fast terminal sliding mode controller is compared with the sliding mode controller method using exponential reaching law to verify the feasibility and superiority of the method proposed in this paper.3.The speed sensorless part is designed by a fuzzy sliding mode observer.A sliding mode observer is built according to the stator current model of the permanent magnet synchronous motor.The fixed sliding mode gain in the sliding mode observer is changed to an adaptive sliding mode gain adjusted through a fuzzy control strategy.The switching function adopts a continuous smooth hyperbolic tangent function.It has a certain effect on reducing chattering.4.According to the combination of the controller and the observer proposed in this paper,a complete vector control system is formed,which is simulated by SIMULINK,and finally the feasibility of the method proposed in this paper is verified.Through the hardware platform,experiments are carried out on the sliding mode observer using the symbolic function and the hyperbolic tangent function,and the system performance of the sliding mode observer using the hyperbolic tangent function is better through the comparison.