Reduction of cogging torque of surface mounted axial flux permanent magnet brushless DC motor with slot shifting technique

Abstract

Cogging torque of axial flux permanent magnet brushless dc motor is detrimental to performance hence it is vital to reduce it. Reduction of cogging torque of axial flux permanent magnet brushless dc (PMBLDC) motor is crucial issue during design. This article presents slot shifting technique to reduce cogging torque of low speed high torque axial flux PMBLDC motor designed for electric vehicle application. Reference axial flux PMBLDC motor of 250 W, 150 rpm is designed with 48 stator slots and 16 rotor poles without incorporating any slot shifting. Three dimensional finite element modeling and analysis is performed to obtain cogging torque profile of initially designed reference machine. Design modification is performed with shifting of stator slots. Stator slots on one side are shifted with respect to stator slots of other side in step of 2° and its influence on cogging torque is analyzed with 3-D finite element modeling and analysis. It is analyzed that cogging torque of axial flux PMBLDC motor is reduced. Slot shifting technique is effective technique to reduce cogging torque of axial flux PMBLDC motor.