High-grade control of switched reluctance machines

This paper formulates the objectives associated with high-grade torque control of SR motors. Low torque ripple is a natural outcome of high bandwidth torque control. Existing torque ripple reduction techniques are reviewed. Smooth torque operation is only uniquely defined together with a secondary objective such as maximum efficiency, maximum torque-speed capability, maximum power factor etc. as the SR motor does not enjoy the inherent distribution between phases that characterises AC-drives. A systematic approach to waveform design is developed, and is evaluated using both simulation and experimental testing of an SR motor servo-drive system. This approach, which can be regarded as a functional equivalent of AC vector control, starts from machine parameters and gives smooth torque operation with maximised torque-speed range or efficiency. Excellent dynamic performance is obtained for speed and position control together with optimised low torque-ripple operation