Examination and linearization of torque control system for direct torque controlled IPMSM

This paper examines the torque response based on direct torque control (DTC) for an interior permanent magnet synchronous motor. DTC with a PI controller for torque control is used in this paper. The relationship between the gains of the PI controller and the torque response is derived based on the transfer function of the torque control loop. In addition, this paper discusses the influence of the nonlinearity of the torque control loop on the torque response. It also proposes a linearization method for the torque control loop based on gain scheduling, and improvement of torque response is achieved. The effectiveness of the proposed method is verified by both simulation and experimental results.