Design of Five-Phase Bearingless Permanent Magnet Assisted Synchronous Reluctance Motor for High Speed Applications

This paper proposes the design of a five-phase bearingless permanent magnet assisted synchronous machine (PMaSynRM) for high speed applications. The bearingless machines are suitable for various industrial and medical applications as they offer wear-free operation, longer lifetime, and higher efficiency by eliminating mechanical bearings. However, the levitation of the rotor is critical aspect in these machines which needs very smooth and sustainable force to hold the rotor and shaft at proper position. In that regard, multiphase PMaSynRM, which offers very low torque ripple and high fault-tolerance, is a suitable candidate for bearingless machine applications. Therefore, this study proposes a five-phase bearingless PMaSynRM that generates desired torque using main five-phase winding and generates the rotor-levitating force using an additional winding. The design procedure of the main motor and the suspension winding has been described in details. A thorough FEA analysis has been provided to show the performance characteristics under various operating conditions. The simulation results show that the motor generate required levitation force at cost of very low suspension winding current. The motor performance with and without the suspension has been compared to ensure desired output of the motor.