Effect of Demagnetization fault on Electromagnetic Field and Related Parameters in Permanent magnet Wind Generator

The irreversible demagnetization fault of permanent magnet in the rotor of large-capacity permanent magnet synchronous wind generator(PMSWG) would happen because of the high temperature and vibration. To analyze the demagnetization fault of permanent magnet, the 1.5MW PMSWG was researched in this paper. Firstly, the mathematical model of two-dimensional transient electromagnetic field was established. Based on time-stepping finite element method coupling with circuit, the electromagnetic field of a 400W PMSWG with similar structure to the 1.5MW PMSWG was simulated under the demagnetization fault. And the simulation results were compared with the experimental ones, by which the accuracy of the calculation method was verified. Secondly, the electromagnetic field distribution of 1.5MW PMSWG running at different positional demagnetization fault was analyzed by using the same calculation method, and the magnetic density variation at the stator yoke was calculated too. At last, the change rules of the air gap magnetic flux density, magnetic leakage coefficient, polar arc coefficient, voltage distortion, no-load counter electromotive force and branch current were compared under different positional demagnetization fault of the 1.5MW PMSWG. And the results in this paper provided a theoretical basis for the research of the demagnetization fault of PMSWG.