A Case Study of Suspension Characteristics of a Bearingless Motor Supplied by Inverters Having Different Voltage and Current Ratings

Abstract

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 have investigated 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. The result of this study shows that the 100V inverter is a better choice for the bearingless motor.