Excitation loss fault detection and protection method of permanent magnet synchronous motor for high-power permanent magnet direct-drive electric locomotive

The invention relates to a field loss on-line monitoring method and a field loss protection strategy of a permanent magnet synchronous motor, in particular to a field loss fault detection and protection method of a permanent magnet synchronous motor for a high-power permanent magnet direct-drive electric locomotive. The method is explained from three aspects of a permanent magnet synchronous motor field loss fault detection method, permanent magnet synchronous motor field loss degree judgment and a permanent magnet synchronous motor field loss fault protection strategy. According to the invention, the excitation loss fault of the permanent magnet of the permanent magnet motor is accurately judged, and the loss caused by the excitation loss of the motor is avoided, so that the maintenance cost is reduced; moreover, the method is simple in algorithm, small in controller resource occupancy and high in robustness, excitation loss faults of different degrees can be distinguished, and the transport capacity is exer