Development and Loss Evaluation of High-Speed PM Synchronous Machine

This paper presents a performance evaluation for a 250 kW–20,000 min⁻¹ high-speed permanent magnet (PM) motor for high-speed applications such as industrial blowers and compressors. Active magnetic bearings used in the high-speed motor floats shaft without contact and realizes direct drive system. The utilization of a high-speed motor for a direct drive system can contribute to making the system size more compact when compared to a geared system. However, this could cause the motor loss density to be high due to the high-output power density in the high-speed motor. For realizing higher-output and higher-speed motor, to clarify loss-generating source in the motor is a very important issue. At this time, we evaluated the electrical characteristics and efficiency of the prototype 250 kW–20,000 min⁻¹ high-speed PM motor and measured the temperature increase by carrying out a heat run test. Furthermore, loss separation was performed. In addition, another fundamental evaluation of windage loss and iron loss that were dominant in the motor loss clarified by above results was performed to improve the efficiency and design accuracy.