Research On Control Strategy Of Permanent Magnet Synchronous Motor Speed Loop

Permanent magnet synchronous motor (PMSM) speed control system is a strong coupling, multi variable nonlinear system. In order to meet the requirements of high reliability and high performance in complex working environment, many problems caused by current coupling, parameter perturbation, external disturbance and other uncertainty factors should be solved. This paper take PMSM speed regulating system as the research object, a nonlinear control strategy based on sliding mode variable structure control theory, the fractional order control algorithm based on particle swarm optimization and the speed sensorless vector control based on model reference adaptive algorithm are studied.Firstly, the structure and classification of PMSM are introduced. The mathematical model of PMSM in three coordinates is established.The mathematical relation of the d-p rotating coordinate is mainly introduced.On this basis, the basic principles of field oriented control of PMSMand the realization of space vector modulation technology are studied, and the current loop of the double closed loop system of PMSM is analyzed and designed.Secondly, the sliding mode controller based on exponential approach law is analyzed. A new reaching law of sliding mode is proposed based on it. The algorithm adjusts speed reaching law according to the distance of system state from equilibrium point, and stability of the control system is proved by Lyapunov law. Sliding mode controller design method which based on the improved exponential reaching law is given, and the sliding mode control system of PMSM is constructed, which improves the control performance of the system.Thirdly, by introducing the theory of fractional calculus, the design method of the fractional order controller with robustness is studied. By using the particle swarm optimization algorithm, the controller parameters are adjusted, and the fractional order speed controller with five parameters is designed. The simulation results show that the proposed controller not only can improve the control quality of the system, but also is not sensitive to the change of the system gain and has stronger robustness.Finally, under the premise of realizing the speed sensor vector control, the vector control system without speed sensor is further studied. This system is based on the model reference adaptive algorithm for speed identification, the integral and proportion parameters of the adaptive law are determined by the particle swarm optimization algorithm with chaos initialization. The speed identification characteristics and the performance of the motor under different conditions of speed sensorless speed control system of PMSM are analyzed by the simulation. The results show that the algorithm can accurately identify the motor speed, and has good static and dynamic performance.