Inverter Voltage and Suspension Characteristics of a Bearingless Motor

A wide magnetic gap consequent-pole type bearingless motor has been developed. The wide magnetic gap makes it difficult to start up and suspend a shaft with reasonable suspension voltage and current. To provide high current, high voltage rating is demanded, although, high voltage causes bad influence on magnetic suspension. In this paper, the authors investigate the start-up and rotational characteristics of a prototype bearingless machine driven by voltage source inverters having the rated voltage of 200V and 100V. When the rated voltage is not suitable, significant problems are occurred. The effectiveness of proper selection in the rated voltage is discussed.