Velocity Loop Control Method of Permanent Magnet Synchronous Motor Based on Differential Feedforward and Parameter Self-tuning

In order to meet the requirements of parameter self-tuning and optimization of velocity loop controller in AC servo system, and to improve the tracking response and bandwidth of velocity loop, a velocity loop control method of permanent magnet synchronous motor based on differential feedforward and parameter self-tuning is studied. The velocity loop parameter self-tuning scheme with zero-pole-cancellation is adopted, and the effective delay time of the velocity loop is taken into account, including the delay time of the velocity filter, the calculation delay of the velocity control algorithm and the equivalent delay time of the current loop. Two adjustable control parameters, stiffness coefficient and mid-frequency phase angle coefficient of mid-frequency, are introduced to adjust the system stiffness and phase margin of the velocity loop respectively. Using bilinear transformation, the self-tuning parameters are discretized and the final PI control parameters of velocity loop are obtained. At the same time, the feedforward compensation of the velocity loop is obtained by combining the differential feedforward algorithm based on low-pass filter. The experimental results show that the parameter self-tuning process of the method is simple, the differential feedforward compensation is stable and reliable, and the one-key parameter self-tuning can be realized. The parameter performance of the tuning is very well, and the control parameter matching control system has excellent control effect.