Two-Steps Slotting Method in Magnet Edge of PMG for Wind Energy Harvesting

Abstract

This paper focuses on the study of how to decrease the value of the cogging torque in an Inset Permanen Magnet Generator. The permanent-magnet generator of an integral slot number with 24 slots and 8 poles was selected and investigated for the purposes of this study. The cogging torque of the permanent-magnet generator can be minimized by combining two slottings in the magnet edge with a gradually inclined surface end. The electromagnetic simulations and analysis of the permanent-magnet generator studied were performed using numerical analysis by means of FEMM 4.2. To obtain a faster computation, FEMM 4.2 was combined with LUA 4.0 programming. Using FEMM 4.2, it was found that by applying two-step slotting in the magnet edge combined with a gradually inclined surface end, the cogging torque of the permanent-magnet generator selected can effectively reduce the cogging torque of the machine by approximately 98.14% compared against the initial magnet model. It can be concluded that the integration of the two-step slotting in the magnet edge and the gradually inclined surface end can effectively reduce the cogging torque of the permanent-magnet generator machine. Furthermore, decreases in the density of the magnetic flux in the core of the permanent-magnet generator can also be found.