A Study on the Shape of a Small Wind Turbine with Fractional Slot Concentrated Winding to Realize Zero Cogging Level

A typical wind turbine has a slot structure. This structure causes a permeance difference in airgap. And this permeance difference creates cogging torque, which acts as a brake when driving the wind turbine. Therefore, the size of cogging torque should be small in order to operate even in breeze. In this paper, in order to reduce cogging torque, first, a comparison of pole slot combinations was performed. In addition, a pole slot combination with a small cogging torque was selected, and a study on the pole arc ratio of a turbine having a FSCW (fractional slot concentrated winding) was conducted. Next, the pole arc ratio and the output characteristics according to the stator and rotor tapering models were examined for the FSCW model. Then, the output characteristics such as cogging torque and efficiency were analyzed by changing the variable of a turbine. Finally, a model that can realize the level of 'zero cogging' was designed and the output characteristics of each model were compared through FEA.