With the rapid growth in the installed capacity of large permanent magnet wind turbines in China

a substantial number of turbines will enter the decommissioning and recycling stage in the near future. Conventional recycling methods for permanent magnet generators suffer from high energy consumption

significant environmental pollution

and an extremely high scrap rate of magnetic steel. Additionally

for permanent magnet motors that have lost magnetization due to faults

demagnetization and disassembly of the magnetic steel are required before supplementary magnetization

which entails considerable labor and material resources. Based on the post assembly magnetization technology for large permanent magnet motors

this paper proposes an in-situ demagnetization and supplementary magnetization method for large permanent magnet motors. First

the demagnetization and supplementary magnetization characteristics of NdFeB permanent magnets are investigated. Then

for the Dongfang Electric 26 MW permanent magnet wind turbine

the pulsed coil structure is optimized

and the mechanical stability under extreme conditions of high magnetic field and strong current is verified. Finally

taking the Dongfang Electric 18 MW and 26 MW permanent magnet wind turbines as examples

a set of integrated megawatt-level permanent magnet wind turbine magnetization and demagnetization equipment is developed. This equipment enables in-situ demagnetization and supplementary magnetization of partially demagnetized magnetic poles for megawatt-scale large permanent magnet motors

providing a technical pathway for the decommissioning

recycling

and operational maintenance of permanent magnet wind turbines.