Electronically Commutated dc Motors for Electric Vehicles

A motor development program to explore the feasibility of electronically commutated dc motors (also known as brushless) for electric cars is described. Two different design concepts and a number of design variations based on these concepts are discussed. One design concept is based on a permanent magnet, medium-speed, machine rated at 7000-9000 rpm and powered via a transistor-inverter power conditioner. The other concept is based on a permanent magnet, high-speed, machine rated at 22,000-26,000 rpm and powered via a transistor-inverter power conditioner. Test results are presented for a medium-speed motor and for a high-speed motor each of which have been fabricated using samarium-cobalt permanent magnet material.