ELECTRIC MOTOR DESIGNS WITH SKEWING STRUCTURE TO MINIMIZE TORQUE RIPPLE

Abstract

A permanent magnet brushless DC motor can be designed with different rotor configurations
based on the arrangement of the permanent magnets. Rotor configurations strongly influence the
performance of permanent magnet electrical motors. The aim of this paper is to compare and
evaluate different rotor configurations for permanent magnet brushless DC motor with or without
skewed stator slots. Nowadays, most of the DC motors are used with surface mounted permanent
magnet rotors, because it is very easy to install and maintain. A finite element method has been
applied to analyze and compare the different geometry parameters and configurations of motors.
This paper focuses on the analysis of electromagnetic structure of two brushless DC motors
with the same rated powers and dimensions of stator and rotor, with different number pole pairs
and slots.
In this paper, the skewing slot is considered for the permanent surface mounted brushless DC
motor for eliminating torque ripples. In order to observe the skewing stator effect, the stator
lamination layers are skewed with different angles. With determined skewing angle, the cogging
torque will theoretically reduce and the harmonic components of the flux density space are
reduced, as well.