A comparative study on two outer rotor PMSMs for in-wheel direct drive under short-circuit faults

Abstract

Two outer rotor PMSMs with different rotor topologies, surface-mounted permanent magnet (SPM) rotor and consequent-pole (CP) rotor are designed for in-wheel direct drive. A comparative study is presented on the characteristics of the two motors under two typical short-circuit faults, three-phase symmetrical short-circuit (SSC) fault and single-phase asymmetrical short-circuit (ASC) fault. The fault current, torque behavior and magnet demagnetization characteristics of the two motors are analyzed and compared in detail. In addition, the post-demagnetization performances of the two motors after a single-phase ASC fault are selected to evaluate the anti-demagnetization ability of the two motors. Results show that the anti-demagnetization ability of CP rotor motor is much weaker than the SPM rotor even having a smaller demagnetization MMF during the short-circuit faults.