Rotor resonances of bearingless switched reluctance motor with axial bias permanent magnet

Switched Reluctance Motor (SRM) has good performance under special environments such as fault tolerance, robustness, tolerance of high temperature or in intense temperature variations. In the meanwhile, SRM has a good feature as magnetic bearing due to the inherent magnetic attraction radial force between rotor and stator poles. This radial force can suspend the rotor. The bearing-less SRM combines advantages of SRM and magnetic bearing. It is very useful for mechanical maintenance and friction of bearing, temperature intense and environmental fault tolerance. Compared with conventional separated magnetic levitation motor, bearingless SRM highly integrates motor and magnetic bearing. It means motor not only supplies rotating torque but also provides levitation force. Therefore, they are particularly suitable to operate in special environments such as high speed application. However, for the high speed machine, it is very important to accurately predict natural frequency of the rotor in the design stage to reduce the possibility of failure. In this paper, the investigated motor consists of two motors. Each motor has 12/12 structure. In order to analyze the rotor natural frequency, finite element analysis and experimental measurements are employed to perform investigation.