An Optimal Direct Torque Control Scheme for DC-biased Vernier Reluctance Machine Drives

An optimal direct torque control (OPT-DTC) scheme is proposed for DC-biased vernier reluctance machines (VRMs) to improve the steady and dynamic performance of drive system. Firstly, the nonlinear model of DC-biased VRM is proposed in synchronous rotating frame. Then, the optimal control theory is employed to the model by designing an optimal torque controller with the ability of regulating zero-sequence current. The feedforward control terms are designed to improve the dynamic response, and the feedback control terms are designed to improve the steady performance. An optimal load torque observer is designed for speed control. Finally, comparative experiments with conventional DTC schemes for DC-biased VRMs are carried out to verify the superior performance of the proposed method, including higher accuracy of torque and flux and faster dynamic response.