Analysis and Reduction of Unbalanced Magnetic Pull Fluctuation of Gram-Ring-Winding High-Speed Permanent Magnet Generator Based on Correction Winding

The fluctuation of unbalanced magnetic pull (UMP) caused by inter-turn short circuit (ITSC) can cause additional vibration for gramme-ring-winding high-speed permanent magnet synchronous generator (GHSPMSG). To solve this problem, a new magnetic field correction winding topology is proposed. When ITSC occurs, the fluctuation of UMP can be effectively suppressed by adjusting the current amplitude and phase of the correction winding, and the fluctuation of UMP can be reduced by 84.2%. Firstly, based on the Maxwell tensor method, the analytical model of the UMP is derived, and the fluctuation is attributed to the time-varying component of UMP caused by the short-circuit loop current. Secondly, a correction method for UMP is proposed, and its correction mechanism is revealed. Based on the analytical method and finite element method, the two correction parameters of current amplitude and phase are optimized. The results show that the magnetic field correction topology has a significant reduction effect on UMP fluctuations caused by ITSC faults. Finally, the ITSC fault experiment and correction experiment of prototype are carried out, and the effectiveness of correction winding is verified.