Reduction of Cogging Torque and Torque Ripple in Exterior Rotor Type BLDC Motor for EV/HEV Battery Cooling System

Abstract

In this study, reduction of cogging torque and torque ripple for an exterior rotor type brushless dc (BLDC) motor for an automotive cooling device were proposed and a design concept for a fan motor for use in a battery pack mounted in an electric vehicle/hybrid electric vehicle (EV/HEV) was presented. Various pole/slot combinations and permanent magnet (PM) pole arc ratios were compared using finite element analysis (FEA), and the PM overhang ratio necessary to sufficiently increase the magnetic flux that enabled coil linkage was determined through 3D FEA. Based on the analysis results, an actual model was produced, experimentally verified, and used to validate the proposed design model.