Design of Bearingless Permanent Magnet Motors Using No Voltage CombinedWindings

Bearingless motors have zero mechanical loss and no-contact operation, making them a compelling technology for high speed, high reliability applications, such as industrial compressors. However, currently published demonstrations of bearingless motors have been limited to low power levels (≤30 kW). This paper investigates the use of a “no voltage” combined motor winding to overcome performance challenges and enable the development of a medium power, high speed bearingless permanent magnet synchronous motor (BPMSM). An optimization framework is developed and used to explore the design space for several designs with different slot and pole numbers. It is shown that candidate designs achieve > 95% efficiency while requiring < 5% of the slot space for suspension current.