Torque Ripple Suppression Of AC Servo System And Optimization Of Speed Loop

Torque ripple is caused by many nonlinear factors in the PMSM servo system, which greatly reduces the performance of the servo system. At the same time, control the motor's speed by using conventional PID control can not make the speed loop has excellent dynamic and static performance, which limits the application of servo system. Therefore, study the torque ripple suppression method of servo system and improve control strategy of speed loop to improve the performance of the servo system has important significance.A AC servo system which consists of current loop, speed loop and position loop was designed with vector control theory. The regulators were designed based on the model of the servo system. And on this basis, designed the AC servo system from the aspects of hardware and software to develop a AC servo driver. Then, experiment research of the driver combined with a PMSM was carried out. The output of the encoder and phase current in the experimental results were in line with expectations.For the nonlinear factors in the servo system, which make the current contain lots of harmonics and cause the problem of torque ripple, a harmonic current detection and suppression strategy was proposed based on multiple synchronous rotating coordinates transform. Improve the waveform of the current by inhibiting the 5th, 7th, 11 th and 13 th harmonic current is beneficial to reduce the torque ripple. The simulation results verify the effectiveness of the proposed method.To improve the performance of the speed loop, a two-degree-of-freedom P-PI speed regulator was designed, and the speed regulator parameter was optimized based on the genetic algorithm. To further reduce speed fluctuation caused by load changes, a state observer based on the motor's state equation was used to observe of load torque, and a feed-forward compensator was designed according to the observed value. Simulation results show that the design of two-degree-of-freedom speed regulator can overcome the shortcomings of conventional PI regulator and verified the feasibility of the optimization method based on genetic algorithm. The simulation results also validate the compensation link of load disturbance based on state observer can greatly improve the anti-disturbance ability of the speed loop.