An Online Torque Sharing Function Method Based on Region Division for Reducing Torque Ripple and Copper Losses of Switched Reluctance Motors

To reduce torque ripple and copper losses, this article proposes an online torque sharing function (TSF) method based on region division for switched reluctance motors (SRMs). The proposed method introduces a region division principle by analyzing the torque-ampere ratio of the incoming and outgoing phases during commutation. Then, based on the divided regions and the root mean square of the current over the conduction period, an online TSF method for phase current regulation, torque tracking error compensation, and phase torque sharing of SRMs is proposed to reduce torque ripple and copper losses. In addition, a hybrid-chopping mode is designed on the basis of the divided regions to reduce switching losses and further suppresses the torque ripple. Compared with the typical and optimization-based TSFs, the proposed online TSF reduces dependence on specific torque waveform functions and avoids complex calculations of turn-off and turn-on angles. A three-phase 12/8 SRM prototype is employed for the experiment under different load conditions to verify the effectiveness of the proposed online TSF.

I. Introduction

The switched reluctance motor (SRM) is raising great attention in the fields of aerospace applications, industrial manufacturing, and electric vehicles because of its simple manufacturing process, fault tolerance, and high power density [1], [2], [3]. However, the torque ripple is relatively larger during commutation due to the special double salient structure of SRMs [4], [5], [6], which can cause vibration and noise in powertrains. This can also have adverse effects on the lifetime of the system in severe cases.