Cancellation of noise and vibration in modular permanent-magnet wind turbine generators

The mechanisms of vibration and acoustic noise emission from modular permanent magnet induction generators differ from those of conventional machines. The structure is treated as a series of independent elastic members subject to several excitation forces at twice supply frequency. With appropriate design, the excitations caused by stator modules can mutually cancel leaving a very small residual vibration. Experimental results from laboratory tests verify the existence of the cancellation effect