A novel direct torque control method for switched reluctance motors based on optimal turn-on angle

Abstract

In view of the disadvantages of negative torque and low operation efficiency in the traditional direct torque control (DTC) for the switched reluctance motor drive (SRD), a novel DTC strategy based on optimal turn-on angle is proposed in this paper. First, the flux hysteresis controller of the traditional DTC is cancelled and the SRM is only controlled by the torque hysteresis controller. The actual rotor position angle is used to divide the sectors instead of the angle calculated by the stator flux, which does not need to select the optimal given flux value, and makes the division of sectors more in line with the inductance characteristics of the SRM. Second, the function for calculating the optimal turn-on angle is designed and the sectors are reallocated. The optimal voltage vector is selected according to the output signal of the torque hysteresis controller and sector position. Finally, the 12-sector DTC method is selected as comparison algorithm and the correctness of the proposed method is confirmed by simulation and experimental results. It is demonstrated that the proposed strategy retains the advantages of the simple structure of the traditional DTC. In addition, it eliminates negative torque, improves the DC bus voltage utilization and torque ampere ratio, and reduces the torque ripple, switching frequency and copper losses.