Model Predictive Direct Torque Control for PMSM with Duty Cycle Optimization

This paper presents an improved model predictive direct torque control (MPDTC) with duty cycle optimization for permanent magnet synchronous motor (PMSM). The conventional direct torque control (DTC) or MPDTC achieves good dynamic and steady state performance by selecting an appropriate voltage vector. However, there is only one voltage vector in one control period, hence the ideal performance of torque can´t be achieved due to the limited number of voltage vectors. In this paper, the concept of duty cycle is applied to MPDTC for PMSM. This method allocates a fraction of one control period for a nonzero voltage vector and the rest of the time for a zero voltage vector. A nonzero voltage vector is selected by minimizing a cost function and its duration time is achieved by the errors minimization of torque and stator flux. Simulation and experimental results show that, the proposed MPDTC with duty cycle control achieves adequate steady state torque performance without affecting the dynamic response, compared with the traditional DTC and conventional MPDTC.