Optimization Design And Cogging Torque Analysis Of Small Permanent Magnet Wind Generator

With the development and utilization of renewable energy in the world, wind power generation is becoming more and more people’s attention.In the wind power generation, the proportion of permanent magnet synchronous generator becomes larger and larger. The interaction between the permanent magnet and slotted core will produce cogging torque, resulting torque ripple, vibration and noise, thus affecting the performance of the motor. The cogging torque is one of the most important issues in the design of permanent magnet wind power generator and its system.This thesis aims to outer rotor permanent magnet wind generator which is widely used in wind solar hybrid system, study on the optimization design and the cogging torque reduce method.The main works are as follows.1. Based on the operation principle of synchronous generator, armature reaction of permanent magnet wind generator was analyzed. Permanent magnet wind generator was designed according to the traditional motor design method, and, the winding magnetic potential harmonic of fractional slot permanent magnet synchronous generator was analysised on the basis of winding theory.2. The finite element method was adopted to establish the 3D electromagnetic model of permanent wind generator. The electromagnetic performance and operating characteristics were analyzed. The optimization technique of permanent magnet wind generation was researched based on chaos optimization algorithm, and the reliable of optimization result was verified by three-dimensional finite element method.3. Based on energy method and Fourier decomposition, the expression of the permanent magnet motor cogging torque was deduced. The influence factors on the cogging torque were analyzed. They include the skew, auxiliary slot, slot widths, permanent magnet pole arc coefficient, segmented magnetic poles and the pole offset cogging torque.4. A stator structure of permanent magnet wind generator with auxiliary teeth was proposed in this thesis. Derivation the Fourier decomposition coefficients analytical expressions of each i slot with an auxiliary tooth, the influence of auxiliary teeth on cogging torque was researched. According to the model and parameters of small permanent magnet wind generator, the influence of auxiliary teeth’s width on the cogging torque was quantitative studied, and the optimal width of the auxiliary teeth was carried out. The coefficient k was introduced, which is equal to the ratio of auxiliary teeth height and stator teeth height, the curve of Fourier decomposition coefficient changing with k is obtained also.5. The model permanent magnet wind generator with auxiliary teeth was carried out. Based on the lever, the dynamic and static measurement method, the corresponding experimental scheme was constitude to test the cogging torque of the model mechine. The experiment results show that the structure of proposed permanent magnet wind generator can restrain cogging torque effectively. It has the value of practical application.