Impact of Smooth Torque Control on the Efficiency of a High-Speed Automotive Switched Reluctance Drive

This paper examines the efficiency performance of an automotive-size high-speed switched reluctance drive. It investigates the impact of a smooth torque control algorithm on the efficiency and losses in the drive. In automotive drives, the application of a dedicated algorithm for torque ripple reduction at low to medium speed is indispensable to avoid excitation of mechanical resonances in the drive train. The predictive direct instantaneous torque control method is compared with efficiency optimized hysteresis current control in terms of efficiency. Dynamic finite-element loss analysis is employed to investigate the source of the efficiency deviation and the results are verified by measurements. The study shows that the requirement for smooth torque leads to a decrease in the drives efficiency and altered loss distribution. The efficiency map comparison reveals that the efficiency degradation amounts to 4–9% for this particular drive.