Impact of zero-volt loop on efficiency of switched reluctance motors

Zero-volt loop (ZVL) is known to be able to reduce peak flux linkages corresponding to iron losses while keeping the same average torque in average torque control of switched reluctance motors (SRMs). However, exploiting ZVL to minimize losses of SRMs has been challenging due to nonlinear correlations caused by extensive magnetic saturation. In this paper, an optimization method to minimize losses while utilizing ZVL is proposed. The Impact of ZVL was investigated by theoretical calculation using a 12 kW, 3820 rpm SRM. The results showed that the utilization of ZVL reduced losses at all speed and partial load. The loss reduction was large especially at medium speed and partial load. At this operating point, the loss reduction was verified by experiment.