Research On The Cogging Torque Reduction Of Flux-Modulated Generator For Wave Energy Conversion

The topology of the flux-modulated generator is optimized in this paper,which belongs to the field of generator topology optimization.Due to the effect of magnet gear,the flux-modulated generator has the characteristics of low-speed direct drive and high torque density.The characteristics make the flux-modulated generator can be applied to the wave power generation system properly.However,the flux-modulated generator has two air gaps,which are inner and outer air gaps,and there are cogging torques in both the air gaps.Thus,the total cogging torque of the generator is huge,so that the performance and accuracy of the power generation system are affected.In this paper,the flux-modulated generator for wave energy conversion is used as the research object,in order to effectively reduce the cogging torque of the inner and outer air gaps,the unequal tooth width structure,eccentric structure and magnet segmentation structure are applied to the flux-modulated generator.Based on these structures,the segmentation structure with unequal tooth width is proposed to reduce the cogging torque of the generator.The method of finite element analysis is used to build the simulation model of the generator,in order to verify the reduction effect.The paper mainly researches in the following aspects:(1)Research on the principle and performance of the flux-modulated generator for wave energy conversion.Firstly,the basic structure and principle of the flux-modulated generator are introduced.Then the finite element simulation model is established to analyze the working principle and the performance of the flux-modulated generator.(2)Principle analysis of the cogging torque reduction methods.Firstly,the cogging torque expression is derived,combining the principle of the flux-modulated generator.Then the reduction principle of unequal tooth width structure is analyzed based on the energy method and Fourier series.The reduction principle analysis of the eccentric structure is carried out.The theoretical optimal eccentricity is derived.The reduction principle of the segmentation structure is analyzed.The simulation model of the generator is established,and the finite element method is applied to the three reduction methods.The cogging torque before and after reduction is compared to verify the reduction effect.(3)The reduction method achieved by the segmentation structure with unequal tooth width is proposed.The reduction principle of the segmentation structure with unequal tooth width is derived.The finite element analysis software is used to establish the generator simulation model.The cogging torque is compared to verify the reduction effect of the reduction method.