Novel of Cogging Torque Reduction Technique for Permanent Magnet Generator by Compounding of Magnet Edge Shaping and Dummy Slotting in Stator Core

Abstract

This paper dealt with the investigation and implementation of the cogging torque reduction technique in permanent magnet generators with a fractional slot stator/rotor combination of 24 slot/18 pole structure. A novel of cogging torque technique in a permanent magnet generator was developed and proposed in the paper. In the study, the cogging torque reduction technique was based on the compounding of two cogging torque reduction techniques, i.e., the magnet edge shaping with dummy slotting in the stator core of the fractional slot number. By employing the CT reduction technique proposed, effects on the decreasing of tangential flux density in the air gap of the permanent magnet generator, while the normal flux density almost remained constant. The tangential flux density is one important parameter regarding the peak of cogging torque in permanent magnet generator or other electrical machine structure. The normal and tangential flux have been analyzed. The cogging torque of the permanent magnet generator was analyzed and presented in the paper. By compounding both cogging torque reduction techniques, i.e., magnet edge shaping and dummy slotting in stator teeth have been expected to achieve the cogging torque reduction. The electromagnetic performance of the permanent magnet generator was performed using a finite element analysis of FEMM 4.2. It has been proved that by combining of magnet edge shaping and dummy slotting in stator teeth can reduce the cogging torque of permanent magnet generator significantly. It has been found that the cogging torque reduction for the proposed structure around 98.08 % compared with the initial structure.