Impact of smooth torque control on the efficiency of a high-speed automotive SRM drive

Switched reluctance motors are an alternative to conventional rotating field machines due to their robust mechanical design and low-cost production. In automotive drives the application of a dedicated algorithm for torque ripple reduction is indispensable as otherwise mechanical resonances in the drive train are excited. In this paper an automotive-sized high-speed SRM drive is investigated for two different control schemes — hysteresis current control and pwm-based direct instantaneous torque control. The main focus of the study lies on the evaluation of both algorithms in terms of efficiency. An analytic loss analysis in selected operating points is carried out and confirmed by simulation. Furthermore a comparison of experimentally derived efficiency maps is presented.