Torque ripple reduction using magnet pole shaping in a surface mounted Permanent Magnet BLDC motor

Abstract

This paper presents torque ripple reduction of a surface mounted Permanent Magnet Brushless DC (PM BLDC) motor using magnet pole shaping technique. Two-dimensional (2D) Finite Element (FE) analysis was carried out on an 18 stator slots and 12 rotor poles PM BLDC motor for various magnet pole shapes by varying the permanent magnet (PM) offset. The results from the analysis are computed and analyzed for various performance parameters like cogging torque, back EMF, developed torque, torque ripple and efficiency. It is observed that there is a considerable reduction in torque ripple by increasing the PM offset from 0mm to 30mm without significant reduction in back EMF and motor efficiency. The study also shows that there is considerable reduction in total harmonic distortion (THD) and harmonic content in the developed torque profile.