Calculation and study on cogging torque of small wind turbine PMSG

Cogging torque is inherent characteristic of PMSG, it affects significantly the cut-in speed of the turbine of wind energy PMSG generation systems. FEM has proved to be the most powerful tool to calculate cogging torque and other important performance of PMSG. In this paper, an improved Maxwell stress tensor method, which can take into account the detailed variation of flux density in the triangular elements within the interested area, is presented to precisely calculate cogging torque. Cogging torque under different design considerations, such as different air gap length, magnet width, stator slot opening, etc, is calculated and studied. Valuable design guidelines which can significantly reduce cogging torque are proposed and verified by the developed PMSGs.