Control for Polyphase Switched Reluctance Machines to Minimize Torque Ripple and Decrease Ohmic Machine Losses

In this paper, instantaneous torque control for switched reluctance machines (SRMs) with an arbitrary number of phases is introduced. Direct portability of this control to machines with any number of phases is achieved by the developed multiphase-torque-sharing concept. This concept is also useful for SRMs where maximum torque can only be achieved by phase overlap of more than two phases. Furthermore, a new torque-sharing strategy, the low-loss-commutation strategy, for predictive pulsewidth modulation direct instantaneous torque control, is proposed that minimizes ohmic losses during commutation of two phases without the use of precomputed current or torque profiles. Additionally, no precomputed switching angles are required. They are determined online by the low-loss-commutation strategy. The strategy is especially useful for operating areas where copper losses dominate, which is usually the case at low speed. The proposed control strategies are validated by simulations and measurements on a drive test bench.