Robust PID/backstepping control design for permanent magnet synchronous motor drive

This paper presents a new control design procedure for permanent magnet synchronous motor (PMSM) speed drive in the case of unknown load torque. The control law is based on the combination of nonlinear proportional integral derivative (PID) regulators and the backstepping methodology. More precisely, we determine the controllers imposing the current-speed tracking in two recursive steps and by using appropriate PID gains that are nonlinear functions of the system state. Moreover, a frequency domain analysis is done to derive under what conditions PID controllers fulfil the robust mixed sensitivity performance condition when applied to PMSM. A comparative study between the proposed PID/backstepping approach and the feedback linearizing control is made by realistic simulation including load torque change, parametric variations, and measurement noise. The results of current-speed tracking show the effectiveness of the proposed method in the presence of strong disturbances. Finally, a virtual experimental setup is simulated to show the feasibility of our control algorithm in practice.