Scaling and design of miniature high-speed bearingless slice motors

Abstract

Recent years have shown a development of electrical drive systems toward high rotational speeds to increase the power density. Applications such as optical systems benefit from rotational speeds at which conventional ball bearings suffer from high losses, excessive wear, and decreased reliability. In such cases, magnetic bearings offer an interesting alternative. This work presents a universally applicable design procedure for miniature bearingless slice motors intended for rotational speeds of several hundred thousand revolutions per minute. Design trade-offs are illustrated and facilitate the selection of Pareto-optimal implementations. An exemplary motor prototype for rotational speeds of up to 760 000 rpm with a rotor diameter of 4 mm and a suitable inverter featuring an FPGA-based controller are demonstrated briefly.