Analysis of cogging torque reduction techniques of a slotless PMBLDC motor

The reduction of cogging torque in Permanent Magnet Brushless DC (PMBLC) Motor is very essential for high performance applications. This paper investigates on the development of a design which reduces the cogging torque to an optimum level. For this purpose, a comparative analysis on the conventional cogging torque reduction techniques as well as that of relatively new design techniques is analyzed. It has been found that cogging torque obtained with parallel magnetization is smaller than that obtained with radial magnetization. Three novel design models has been investigated and the result obtained for a model having one bifurcation on stator tooth with different magnet width on rotor poles offered least cogging torque both in terms of peak and average value of cogging torque. The result obtained from the combination of conventional as well as the relatively new methods to reduce cogging torque are found to reduce cogging torque up to 88% and hence can be applicable in high precision applications.