Performance simulation of a high-speed magnetic bearing two-phase drive for special applications

There are a number of special applications which require high-speed high-power motor drives. A typical example is a spindle drive which often operates at speeds in excess of 30,000 r/min. The majority of these drives are supported by air bearings whist magnetic bearings are used for essentially highly specialised applications. Most spindle drives use three-phase induction motors which are supplied by three-phase inverters. This paper describes the performance simulation of a two-phase motor drive that has been developed recently for a spindle drive application. The motor is supported by magnetic bearings and rotates at 30,000 r/min, developing 1.0 kW of shaft power. The advantages of using a two-phase drive with magnetic bearings rather than a three-phase drive are discussed. A comparison is presented between the use of magnetic and air bearings.