Fault tolerant in-wheel motor topologies for high performance electric vehicles

The use of in-wheel motors, often referred to as hub motors, as a source of propulsion for pure electric or hybrid electric vehicles has recently received a lot of attention. Since the motor is housed in the limited space within the wheel rim, it must have a high torque density and efficiency, and survive the rigours of being in-wheel in terms of environmental cycling, ingress, shock and vibration and driver abuse. Finally, to ensure adequate levels of functional safety are met it is essential that failures do not lead to loss of control of the vehicle. This paper presents studies of a fault tolerant concept for the design of in-wheel motors. The study focused on achieving a high torque density and the ability to sustain an adequate level of performance following a failure. A series of failures are simulated and then compared with experimental tests on a demonstrator motor.