Cogging Torque Reduction in Permanent Magnet Brushless DC Motor by using Various Design Modification Techniques

Abstract

Cogging torque is a problem for continuous motion applications like scanning, contouring and mainly positioning applications that requires smooth and accurate motion. It degrades the performance and the life of the motor. Cogging torque cannot be completely omitted but can be reduced drastically using various design modification techniques. This paper focuses on reducing cogging torque in BLDC using three different techniques like stator slot modification, rotor magnet modification and skewing of stator slots and rotor magnets. The result obtained by combining these three techniques has yielded a new model with reduced cogging torque and trapezoidal Back Electromotive Force as compared to the conventional BLDC motor. Also, the cogging torque values for different rotor magnets and stator slots shapes are calculated and studied using Finite Element Analysis (FEA). A detailed thermal analysis of the same model presents the temperature and heat flow plots using Computer Aided Design (CAD).