Adaptive Optimal Control for PMSM Servo System

This chapter proposes an adaptive optimal control scheme to minimize the effect of disturbances and uncertainties of PMSM. In the speed regulation loop, an adaptive speed controller is designed, which not only regulates the speed perfectly but also is robust against wide range variation of parameters and external disturbance of PMSM. Unlike the traditional speed controller, the proposed controller includes an adaptive law to compensate the distorted model parameters and disturbances in real-time, enhancing speed performance. The stability of the proposed speed controller is fully proven by using Lyapunov theory. Meanwhile, a PI-type optimal current controller is established in the inner control loop to achieve the current tracking and limitation. By easily selecting appropriate performance indexes, the proposed controller can balance between control input magnitude and current tracking error. Finally, the validity of the proposed control scheme is verified through simulations and experiments. For a comparative study, four different control strategies, that is, the proposed control, super twisting sliding mode control, PI control and disturbance observer-based control, are carried out to demonstrate the superiority of the proposal.