High-Performance Torque Controller for Switched Reluctance Machine

This paper proposes a high-performance torque control scheme for the Switched Reluctance Machine (SRM), which includes a PI controller, feedforward compensation, high-frequency compensation, and phase-shifted gating functions. A systematic procedure for the PI controller design is presented based on the total torque large-signal model and its linearized small-signal models at different operating points. The procedure ensures stability and good bandwidth of the PI controller for the entire range of plant parameter variations. Two different feedforward compensation methods are proposed to improve the dynamics beyond that of the PI controller, one based on real-time computation and another based on a stored look-up table. Further improvement is achieved using a high-frequency compensation to reduce torque ripple at high-speed operations. A range of gating functions are studied to avoid sudden changes in the phase current references. An appropriate gating function that ensures a good trade-off between pulsating torque and RMS value of phase current is selected. The proposed controller with the selected gating function is validated through simulations and experiments on a 4-kW, 8/6-pole, 4-phase SRM drive. Through experiments and simulations, the performance of the proposed controller is compared against an existing state-of-the-art torque control technique at various speeds and torque levels. The proposed controller shows significant improvement in the reduction of pulsating torque as compared to that of the state-of-the-art controller.