Design procedure for low cost, low mass, direct drive, in-wheel motor drivetrains for electric and hybrid vehicles

Direct drive, in-wheel motors are ideal for electric and hybrid vehicles because the packaging of the drivetrain is so simple, because drivetrain losses are eliminated, and because individual wheel control improves handling and safety. In applications where cost is not a constraint, e.g. solar car racing, direct drive, in-wheel motors are the norm. In-wheel motors are also regularly demonstrated in concept vehicles. However, in-wheel motors are not used for production vehicles because of their high cost and high-unsprung mass. This paper describes a project that addresses these issues through the use of a novel, multiple-airgap, axial-flux, switched-reluctance motor with optimized packaging and low cost electronics. The emphasis of the paper is on how to design the system as a whole.