An Improved Control Strategy to Reduce Torque Spikes and Ripple for Bearingless Switched Reluctance Motors
Qiang Yu, Xin Cao, Xu Deng, Tao Zhu, Zhiquan Deng, Chengzi Liu
Abstract
Direct torque control, direct instantaneous torque control (DITC), and direct force control strategies have been well applied in bearingless switched reluctance motors (BSRMs), which can obtain good torque and levitation characteristics by hysteresis-loop control method. However, hysteresis-loop control method can result in torque ripple due to loop width, which increases the rms currents. On the other hand, commutation at the maximum inductance can result in torque spikes, which can deteriorate the commutation process. Therefore, this article proposes an improved control strategy to further reduce torque spikes and ripple for BSRMs. In the proposed strategy, the torque sharing function is investigated to make torque transition smoother. Moreover, model predictive control (MPC) method is employed to replace the hysteresis loop, which reduces the torque ripple and reduces the rms currents. At the same time, torque—ampere ratio can be improved as well.