Design of in-wheel permanent magnet vernier machine to reduce the armature current density

Permanent magnet vernier machines, PMVM, have magnetic gear effect, which yields a large torque and increases torque per current. We, the authors, have focused on an outer rotor type in-wheel machine for EV so as to take the advantage of PMVM and previously proposed a machine with NdFeB bond magnets which satisfied required characteristics in, both torque and output power, whose characteristics were verified by a computer simulation. However, the current density in armature winding conductor was very high. It wasn't suitable for in-wheel system without cooling system. This paper, therefore, proposes an improvement of the disadvantage in the previously proposed machine. Consequently, the current density has decreased to half compared with the unimproved machine. That magnitude was small enough to apply the machine to in-wheel system.