Effect of Combination Fractional Slot Number and Slotting Technique on the Cogging Torque in Permanent Magnet Machines

The purpose of this study is to find out the effect of the integration of both fractional slot number technique and the slotting by one step in the magnet edge on the cogging torque mitigation in a permanent magnet generator. The powerfulness of the method was approved using numerical analysis and analytically. To compare the performance result of the permanent magnet generator, three distinct structures of permanent magnet generators have been investigated and analyzed. In our study, the original structure of the permanent magnet machines has assumed as the base of permanent magnet generator performance. The magnet rotor was fully cover without any slotting, while the stator core is also without any slotting. Since the magnet was a full cover, the height of the magnet in all parts was the same. The magnet height in the edge is the same as the center of the magnet. At the beginning of the analysis, the structure of fractional slot numbers with 24 slots and 14 poles was selected. The result of both two cogging torque decrement techniques was investigated and the cogging torque subtraction result was contrasted with the initial cogging torque peak value. For the detailed examination of this study, it has been applied FEMM 4.2. It is obtained the cogging torque value of the proposed machine structure of 97.27 % contrasted with the original machine model.