A Novel Partial Slot Unwounded Method for Electromagnetic Vibration Reduction of Large Electric Machines

A novel winding modification method to reduce the electromagnetic vibration noise for large electric machines is proposed in this paper. First, detailed analytical model is provided for the distribution of air-gap flux density and the radial force density. The main source of electromagnetic vibration is identified through the analytical model and the experimental data. Then, a method based on multi-objective optimization of partial slot unwounded (PSU) is proposed to reduce this electromagnetic force that causes the main vibration. The method is more flexible and provides better vibration reduction than the traditional method of changing the winding coils out of regular belt distribution. Finally, the effectivity of the proposed method is verified by FEM results. The electromagnetic force that causes the main vibration is reduced from 7.6 kN/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 2.7 kN/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the amplitude of total vibration is expected to reduced from 21.2mm/s to 8.3mm/s.