Suspension Performance and Fault-Tolerance Principle of High-Speed Permanent Magnet Synchronous Generator

The unbalanced magnetic pull (UMP) caused by inter-turn short circuit (ITSC) can cause serious damage to wrap-around high-speed permanent magnet synchronous generators (HSPMSG). In order to solve this problem and further improve the reliability of the generator operation, the new method that transform the UMP into suspension force in fault-tolerant operation by the correction winding is proposed, and a stable suspension force can be also provided by the method during generator normal operation. Firstly, based on the winding structure of the wrap-around HSPMSG, the UMP caused by ITSC fault is calculated, and the key factors affecting the UMP are determined. Secondly, a mathematical correction model for the UMP is established, the principle of the UMP being transformed into suspension force is revealed, and the relationship between the UMP and the suspension force is clarified. The effect of the suspension force on bearing life is further analyzed, the results show that the suspension force can offset 86.5% of the gravity of the rotor and significantly improve the bearing life. Finally, the ITSC fault experiment and the correction experiment of prototype are carried out, and the effectiveness of the correction winding in fault-tolerant operation is verified.