Wind turbine generator and maintenance method thereof

A wind turbine generator, comprising:

• a main shaft which supports a wind turbine rotor;
• a main bearing which rotatably supports said main shaft;
• a generator provided with a generator rotor and a stator;
• and
• a sleeve coupled to said generator rotor and inserted onto said main shaft,
• wherein said stator includes:
• stator magnetic poles arrayed in a circumferential direction of said main shaft;
• and
• first and second stator plates coupled to said main shaft relatively rotatably thereto to support said stator magnetic poles and arranged in an axial direction of said main shaft,
• wherein said generator rotor includes:
• rotor magnetic poles arrayed in said circumferential direction;
• and at least one magnetic pole supporting structure coupled to said main shaft to support said rotor magnetic poles and provided between said first and second stator plates,
• wherein said first and second stator plates and said rotor magnetic pole supporting structure are configured such that said rotor magnetic poles and said stator magnetic poles are detachable from said sleeve, and
• wherein, with respect to said first and second stator plates and said rotor magnetic pole supporting structure, positions at which said rotor magnetic poles and said stator magnetic poles are detached from said sleeve are closer to said main shaft as the distance from said positions to a closer end of said main shaft of said generator diminishes.