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, 3010 km, Darwin-Adelaide World Solar Challenge solar car race, is described. The brushless DC motor was more efficient (97.5% compared to 92-95%) and lighter (8.3 kg compared to 12-16 kg) than all other direct-drive motors, and more efficient than all motor/gear combinations, in the race. This was 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.