Design of a slotless PM-motor for a screw compressor drive

This paper describes the design of a slotless permanent magnet (PM) machine. The application is a motor for screw compressor drives. The screw compressor is a high speed apparatus and runs generally at speeds of 6000 rpm and above. The screw compressor intended for this machine runs at 12000 rpm with an output power of 80 kW. Conventional drives use a standard motor and a gear box. The removal of the gear box enables a higher total system efficiency. The use of a PM enables a high motor efficiency