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This article investigates the magnetic force phenomenon in permanent magnet (PM) wind turbine generators. Due to the presence of PMs, the inherent and ever-existing magnetic force between the stator and rotor becomes one of the most critical phenomena in these generators. Whether it is during the assembly process, throughout the manufacturing stages, or when the generator is in operation, it is essential to calculate these forces and their distributions. The unbalanced resultant force due to the manufacturing tolerances, rotor eccentricity, or bearing displacement under high wind loads can be calculated with the force distribution function, which is derived from the air gap flux density using two-dimensional (2-D) magnetostatic finite-element analysis (FEA). The obtained results show good agreement with the figures based on the time-stepping FE approach. The effective force distribution derived can be sufficiently employed with three-dimensional (3-D) FEA to study the overall mechanical structure and integrity of the wind generator design.
Date of Publication: July-Aug. 2013