Research Of Sensorless Control For Permanent Magnet Synchronous Motor Based On Doubly-Sliding-Mode

Permanent magnet synchronous motor(PMSM)is simple in structure and can work reliably for a long time,it is widely used in various fields.PMSM speed control system in the project there are internal parameters perturbation and external disturbance and other uncertain factors,we need to study its advanced control method in order to achieve PMSM high-performance control.In order to improve the robustness of the PMSM control system and improve the performance of the speed control system,this paper proposes a PMSM control system based on the double sliding mode control strategy.The sliding mode speed controller and the sliding mode position observer are designed to replace the traditional PI controller and mechanical position sensor in the control system.In order to improve the dynamic quality in the design of the sliding mode speed controller,this paper adopts a method based on the reaching law.Based on the analysis of the causes of the chattering of the constant velocity approximation law,a new variable index exponential sliding mode velocity controller with time-varying switching gain is designed.In this method,the time-varying switching gain is formed by adding the time-varying coefficients to the constant term of the law,and the power function of the state variable is introduced in the exponential term,which accelerates the approach speed and solves the problem of constant velocity approximation law cannot give attention to both the rapid and weaken the system chatter,so that the dynamic performance of the system has been improved,and improve the performance of the controller.The sliding mode observer can obtain the rotor position and speed information by measuring the voltage and current of the PMSM,but the high frequency noise and ripple in the back electromotive force will directly affect the estimation accuracy.Therefore,this paper has made a series of improvements to the traditional sliding mode observer,including the use of saturation function,the design of a low-pass filter with variable cut-off frequency,the introduction of Kalman filter to filter the back electromotive force again and the use of phase-locked loop extraction rotor position and speed information.The improved sliding mode observer can significantly reduce the buffeting,effectively suppress the interference caused by the measurement error and the system error,and obtain the more smooth back EMF information,which makes the estimation information more accurate and the performance is more improve.At last,according to the control method designed in this paper,the simulation of PMSM speed control system is completed in MATLAB / simulink environment.At the same time,the hardware experiment platform of permanent magnet synchronous motor control system with STM32F103 chip is built,and the software design of the system is completed,the simulation and experimental results show that the proposed strategy is effective and achieves the expected results.