Design of an in-wheel motor for a solar-powered electric vehicle

The design of an in-wheel electric motor for the solar-powered vehicle ‘Aurora’, entered in the 1996, 3010km Darwin ~ Adelaide World Solar Challenge solar car race is described. Compared to other entrants in the race, the brushless DC motor is more efficient (97.5% compared to 92-95%) and lighter (8.3kg compared to 12-16kg) than all other direct-drive motors, and more efficient than all motodgear combinations. This is achieved by the use of high flux-density rare-earth magnets, and computer aided optimisation of an axial-flux configuration consisting of a Halbach magnet array and an ironless air-gap winding.