Optimum Pole Number Combination of a Buried Permanent Magnet Bearingless Motor and Test Results at an Output of 60 kW With a Speed of 37000 r/min

An ideal pole number combination of motor and suspension windings is essential for bearingless motors. In this study, the performance of a high-speed, high-power buried permanent magnet bearingless motor using several pole combinations is compared. The torque, power factor, efficiency, suspension force amplitude and fluctuation, and eddy current loss are compared for a 37000 r/min bearingless motor with an output of 60 kW. The basic experimental results of the test bearingless motor with the optimum pole number combination are presented. The test machine has an output of 61.9 kW with an efficiency of 94.9% at a speed of 37000 r/min and a static radial force of 530 N. The radial force and torque density are as high as 1.01 kgf/cm
²
and 64 Nm/L, respectively. The output of 61.9 kW is the highest experimentally obtained for bearingless motors.