Research On Speed Estimation Of Permanent Magnet Synchronous Motor And Self-Coupling PI Current Loop Control

Modern permanent magnet synchronous motors mostly use speed(position)sensors to detect the speed or position information of the motor.However,the internal environment of the motor is relatively complex and harsh,which affecting the accuracy of the sensor,and even causes the motor to lose control.This paper mainly studies interior permanent magnet synchronous motor.Firstly,the mathematical model of the permanent magnet synchronous motor based on three different coordinate systems was introduced in detail.Then,the space vector pulse width modulation(SVPWM)and several commonly used methods of vector control were analyzed.Based on the mathematical model of the permanent magnet synchronous motor in the synchronous rotating coordinate system,a piecewise exponential switching function was designed according to the sliding mode variable structure control theory to replace the sign switching function in the sliding mode observer,and the stability of the control system was analyzed using the Lyapunov stability criterion.The simulation and experimental results show that the improved sliding mode observer improves the estimation accuracy of the system,the chattering problem of the system was suppressed,and the stability is stronger.Because the parameter setting of the current loop PI controller in the sensorless vector control system of the permanent magnet synchronous motor is too dependent on the motor parameters and is susceptible by external factors,and the PI controller has an inevitable contradiction between rapidity and overshoot.To solve the above problems,this paper proposed a controller based on self-coupling PI(Self-CouplingPI;SC-PI),which defines the system dynamics and the internal and external uncertainties as the total disturbance,thereby transforming the nonlinear uncertain system into a linear uncertain system,and then constructing the error dynamic system under the anti-phase excitation of the total disturbance,and designing SC-PI control law model and tuning methods accordingly,and an Adaptive Speed Factor(ASF)model was designed further.The sensorless vector control algorithm of permanent magnet synchronous motor based on SC-PI controller effectively solves the problem that PI parameter setting is too dependent on the mathematical model of the motor,and has the characteristics of strong anti-interference ability,high control performance and fast response speed.Based on the improved sliding mode observer vector control strategy,combined with the SC-PI current controller proposed in this paper,whole control algorithm model was established on the MATLAB/Simulink simulation platform.By the simulation results,it is verified that the improved sliding mode observer and SC-PI controller have higher observation performance and stronger robustness.Finally,the correctness of the improved sliding mode observer was verified by the HIL semi-physical simulation platform,and the SC-PI controller was experimentally verified by bench test.The results show that the improved sliding mode observer and the SC-PI controllers has good control performance.