High-performance electric machines for renewable energy generation and efficient drives

Advances in permanent magnets, electronics and design techniques over the past thirty years have lead to the development of a new generation of electric machines. Sintered rare-earth neodymium-iron-boron magnets have a magnetic energy product up to an order of magnitude larger than those of alnico and ferrite magnets, with high remanence and coercive force. Coupled with new smart power electronics and the use of advanced computer aided design optimisation, the new machines are of high efficiency and and/or compact size. Some state of the art developments of high-performance machines are reviewed with particular examples drawn from a number of novel designs developed by UTS and CSIRO. These designs include a 4 kW solar car in-wheel motor; a 1.5 kW solar-powered, water-filled, submersible, borehole pump motor using a surface magnet rotor; a 75 kW high-speed compressor drive with 2-pole cylindrical magnet rotor; a 20 kW direct-drive generator for wind turbines with very low starting torque using an outer rotor with surface magnets; and a very low cost efficient variable speed AC drive for induction machines.