Optimal Design of Magnetizing Fixture to Reduce Cogging Torque in Brushless DC Motor

Abstract

Several researchers have studied design techniques to reduce cogging torque in brushless PM motors [1]. Arcshaping PM or arc-shaping stator teeth was used for making a sinusoidal air-gap magnetic flux density (MFD). However, this increases manufacturing cost and effort [2]. To overcome this problem, research activities on a conventional winding arrangement method have been conducted [2]. However, with this method, it is difficult to obtain free space for winding arrangements with increasing pole number. Also it cannot take into account the precise environmental conditions of PM. For optimal sinusoidal air-gap MFD distribution in surroundings of PM, the pole shape design on the magnetizing fixture is required. In this paper, a design method for magnetizing fixture based on [3] is proposed to create a sinusoidal air-gap MFD distribution in the brushless DC motor. Additionally, to optimize the rotor pole shape, we utilize the sequential RSM and FEM.