Efficiency Improvement in High Speed Operation using Slot-less Configuration for Permanent Magnet Synchronous Motor

High power and high efficiency in high-speed operation (e.g. 50,000 r/min) is required for motors used for vacuum cleaners. The permanent magnet synchronous motor (PMSM) is a high efficiency motor in the usual operation region. Large iron losses are generated in conventional PMSMs during high speed operation; therefore, the motor efficiency decreases considerably. In this research, we examine the improvement of the iron loss in the high-speed operation of the PMSM. It is expected that the iron loss of the slot-less PMSM can be greatly decreased because there are no teeth in the area where the magnetic flux density is high. Comparative consideration of the slot-less PMSM and the conventional PMSM with the distributed winding is performed. The slot-less PMSM is suitable for use in vacuum cleaners, which do not demand a large starting torque.