Study on the Dynamics of the In-Wheel Motor System

In this paper, a novel in-wheel motor (IWM) topology scheme is brought forward. This scheme aims at conquering the unspung mass increase because of the motor embedded in the wheel and the motor magnet gap (MMG) deformation that arose by road surface roughness excitation. By mounting rubber bushings in the IWM device, the IWM mass is flexibly isolated from the unsprung mass. Synchronously, the rubber bushings can absorb the vibration energy from the road surface and abate the MMG deformation. Primarily, the quarter vehicle vibration dynamic model is set up. Then, bushing stiffness and damping are analyzed plainly. By contrastive simulations of the two types of IWM schemes with or without bushings, some useful results come out. With the rubber bushings, the body vibration acceleration, the tire dynamic load, the suspension dynamic travel, and the magnet gap deformation (MGD) can all achieve distinct improvements. In particular, MGD gets more than 90% improvement. Consequently, rubber bushings can observably improve the IWM vehicle vertical dynamics. The scheme and the analysis approach can be contributive to the development of the IWM propulsion system.