Study Of High Rigidity Control Strategy Of AC Permanent Magnet Synchronous Motor

With the advantages of simple structure and excellent control performance, the permanent magnet synchronous motor(PMSM) has been widely used in recent years. Focused on the response performance of PMSM servo system, the high rigidity control strategies are investigated in the thesis, which is for improving the response speed of the servo system and enhancing the anti-disturbance ability of the speed control.Firstly, considering that the performance of PMSM servo system is related to regulator parameters closely, it is important to design reasonable control gains to achieve the high rigidity of the servo system. By analyzing the mathematical model of various control parts of the servo system, the setting principles of appropriate performance indices for current loop and speed loop are introduced respectively on time domain and frequency domain. Meanwhile, concerning about the impact of inertia on the response of speed, two methods for inertia off-line identification are studied to measure the parameter accurately. Based on the above discussion, tuning strategies of PI parameters are put forward.Secondly, in order to enhance the rigidity of servo system and reduce the effects caused by load torque disturbances, the servo system speed response model under load torque disturbance is analyzed. Based on the relationship between frequency domain characteristics of the disturbance model and the parameters of speed PI regulator, a variable gain PI control method is proposed to reject disturbance. Meantime, a load torque observer based on Kalman filter is designed and the estimated load torque is handled as feed-forward compensation part to improve the anti-disturbance ability of the servo system. Considering the engineering applications, observer parameter variation is discussed, and the real-time implementation of the load torque observer is analyzed briefly.Finally, the load torque observer is implemented by FPGA in hardware approach, which guaranteed the response of estimated load torque, and the other improved control algorithms are mainly realized by ARM microcontroller. By optimizing the PI parameters of the current loop and the speed loop, the response speed of the current and speed is improved. With the variable gain PI control method based on estimated load torque real-time compensation, the speed fluctuation and the adjustment time caused by disturbance can be reduced. The simulation and experimental results verified the validity of the above control strategies.