Levitation control of an improved modular bearingless switched reluctance motor

In order to reduce coupling between torque and suspending force in conventional bearingless switched reluctance motor (BLSRM), one 12/12 hybrid-stator-pole structure BLSRM was investigated. In this structure, motor consists of two single phase motor. Biased flux is provided by axial permanent magnet, which is installed between two motor in axial direction. However, axial permanent magnet occupies axial space, which results in increased axial length and decreased critical speed. Therefore, an improved modular BLSRM is proposed in this paper. In order to reduce axial space and improve critical speed, permanent magnet is designed to install in stator yoke. To realize steady levitation during rotor rotating, one simple levitation control strategy is put forward, which is benefitted from natural decoupling between torque and suspending force. In addition, digital control system including torque and suspending force is designed by means of TMS320F28335 and experimental platform is established. Finally, the improved BLSRM can be steadily levitated in the static and rotating conditions by experimental results.