Winding Method to Reduce Vibration and Loss Caused by Fractional Slot of Synchronous Machine

Abstract

Fractional-slot windings are widely used in rotating machines in order to improve the output voltage waveform, increase the design flexibility, and gain many other advantages. However, fractional-slot windings are known to produce different harmonic components such as an even order and/or fractional number of space flux harmonics compared to integral-slot windings. These harmonics may increase stray losses and cause stator core vibration.  This paper describes an analysis of space flux harmonics and proposes new winding methods such as “novel interspersed windings” to reduce these harmonic components. The proposed winding methods were verified by numerical analysis and model tests.