Fractional slot winding design method of Permanent-Magnet Synchronous Machines using Slot Star Diagram

In recent years, Permanent-Magnet-Type Synchronous Machine is used in many applications for industrial drive for the improved performance. Especially, for the armature winding, the fractional slot winding is known about the improved efficiency performance and torque ripple performance. In this paper, we proposed the irregular pitch winding on the fractional slot winding to improve torque ripple characteristics, used the rectangle shape magnet. At the case of the conventional regular pitch winding, we can calculate the winding factor K_w by the typical formula. But at this irregular pitch, it is too difficult to seek K_w from the formula. So, we propose the solution to seek K_w used “Slot Star Diagram” on the irregular pitch, and we seek the optimum the irregular pitch angle to decrease the harmonic component in EMF considered with the field magnet shape. For it, we explain how to derive by using “Slot Star Diagram” for the winding arrangement to be simply. And in the case of the odd and even slot, it has given the examples for each, which describes the procedure of derivation of the winding factor K_w.