Weight-Reduction Design Based on Integrated Radial-Axial Magnetic Bearing of a Large-Scale MSCMG for Space Station Application

For space application weight and power consumption are the key parameters of an actuator for attitude control of spacecraft. In this paper, weight-reduction design based on a novel combined radial-axial magnetic bearing (CRAMB) in a large-scale magnetically suspended control moment gyro (MSCMG) for space station application is proposed. The CRAMB consists of a radial magnetic bearing (RMB) unit and an axial magnetic bearing (AMB) unit. Two CRAMBs can control the 5-degrees of freedom of the high-speed magnetically suspended rotor. According to the requirement of a large MSCMG for a space station, the CRAMB with permanent magnet bias is modeled (based on an equivalent magnetic circuit method), designed, and tested. Compared with the original magnetic bearings in MSCMG fabricated, the number of magnetic pole is reduced from eight to four for RMB unit based on the CRAMB, the weight of magnetic bearings can be reduced from 35.4 to 30.8 kg (reduced by 4.6 kg), and the volume is reduced from 0.00456 to 0.00394 m³ (reduced by 16.3%), when the MSCMG outputs the same angular momentum of 1200 N · m · s and the same torque of 209 N·m. The maximum power consumption of the proposed CRAMB system is decreased by 15.6%.