Design and Analysis of Modular Permanent Bearingless Switched Reluctance Motor

In order to increase structure compactness, critical rotor speed and output torque of existing 12/12 bearingless switched reluctance motor(BSRM) with axial biased permanent magnet(PM), an improved modular permanent magnet bearingless switched reluctance motor(PM-BSRM) is comprehensively investigated. At first, this paper introduces design structure, and generation mechanism of torque and suspending force. Secondly, there is full consideration for this paper to design motor parameters, including several pole arc and rotor structure, which can fulfil some requirements such as self-starting capability, suspending force maximum value and selection of secondary air-gap. Thirdly, characteristic such as output torque and suspending force of proposed motor and others are mainly analysed. Finally, according to above analysis and research about motor characteristics, a prototype motor is designed. And through experiments, it could be found that the motor performance gets improved.

I. Introduction

In recent years, bearingless motor has been more widely focused, because comparing with others, it has many advantages, such as its wide power range, no mechanical friction, high precision and speed characteristic. Many industry experts and scholars widely use it in high speed or high stability fields^[1]. As we all know, switched reluctance motor (SRM) has a unique double-salient pole structure, and its rotor is not made of permanent magnetic material and has no windings. Many excellent characteristics promote its development, for instance, it has low cost, high fault-tolerant capability and it can get normal operation in harsh situations^[2]–[4]. In addition, because it combines the advantages of bearingless motor and SRM, bearingless switched reluctance motor (BSRM) has been used in more and more applications^[5].