Modeling and Experimental Verification of Multilayer Winding Method for the Vibration Improvement of Electric Motor With Sub-Harmonics

Fractional slot concentrated winding synchronous motor has great electrical properties such as high torque density, low cogging torque, and low torque ripple. However severe vibration is caused by sub-harmonics which are below the fundamental harmonic order in magnetomotive force (MMF). In this paper, four-layer winding is proposed to the motor design for sub-harmonics reduction instead of two-layer winding because sub-harmonics are affected by the ratio of armature winding and magnet field. To prevent the four-layer winding from lowering electromagnetic characteristics, a discrete design optimization is performed. Finally, to verify the proposed method, two motors of 12 -slot/10pole with four-layer winding and two-layer winding are manufactured and their performances are compared.