Overview on Various Techniques for Reduction of cogging torque and torque ripples of Permanent Magnet motors of different rotor configurations

Abstract

Different types of PM motors are finding applications substituting squirrel cage induction motors for its smooth control, energy efficient operations and high power density. Even though these motors are energy efficient, they are affected by ripples in the torque and cogging torque. Torque ripples are nothing but the oscillations leading to various mechanical issues like vibrations, rotor stress and noise. Factors like non sinusoidal distribution of flux, saturation, wrong selection of slots etc are creating ripples in developed torque. These ill effects are deteriorating PM motors performance in starting and steady state. Now a days reducing cogging torque and ripples in torque gained significance in the motor design. So in this work, various techniques to reduce ripples in torque and to reduce cogging torque of various PM motors has been investigated and reported.