Disc motor with reduced unsprung mass for direct EV wheel drive

A new drive system for electric vehicles is presented. An axial flux disc motor is used. The stator of the machine is attached to the chassis whilst the rotor directly drives the wheel. This arrangement reduces the unsprung mass compared with a conventional wheel drive and also, because of the machine geometry, permits movement of the wheel as it is perturbed by the road. The motor is modelled using 2D and 3D finite element techniques and estimates are given for the reduction in torque and induced EMF when the rotor disc and stator are misaligned