A Novel In-Wheel Motor Drive System of Multiple High-Speed Motors Integrated with Magnetic Gear for Electric Vehicle

A technical innovation for the downsizing of motor system is necessary to realize the saving energy, and roomy and comfortable car interior space in electric vehicles. This research focuses on magnetic gears as a breakthrough because it can achieve maintenance-free, low vibration and low acoustic noise by non-contact power transformation, thus they are effective for the downsizing of system by the high-speed rotation of a motor because of solving drawbacks due to the contact of teeth in mechanical gears. However, there exists some challenges such as the low mechanical strength and the reduction of the gear efficiency on conventional magnetic gears in the high-speed drive. In this research, a novel in-wheel motor system of multiple high-speed motors and Magnetic Multiple Spur Gear (MMSG) for the electric vehicle is proposed. The MMSG can achieve the high mechanical strength and high transmitted efficiency by the structure separating several input rotors even in the speed region of 50000 min-1. Moreover, the drive system realizes the drastic downsizing and the high efficiency by MMSG transforming the input of multiple high-speed motors. In this paper, the characteristics of proposed drive system with MMSG are clarified by the simulation and experiment.