Research On The Design Methods And Corresponding Electromagnetic Characteristics For The Asymmetric-paths Windings In AC Machines

The asymmetric-paths winding is a novel type of ac windings with the fractional ratio of the pole number to the path number.It is a good solution to solve the choose contradiction between the number of poles and the number of parallel paths in the design of large synchronous generators,and presents a better balance on the efficiency and economy.However,in practice,considering the asymmetrical distributions of path windings,there could be some novel design and evaluation problems,owing to many connection combinations and the circulating current between path windings.Aimed at the problems above,in this dissertation,some studies are carried out,including the evaluation criterion of the asymmetric degree,the optimization design of the connection and arrangement,the calculation of the circulating current between parallel paths,the electromagnetic force of slotconductors,the synchronous parameters,and corresponding change rules.Firstly,an improved criterion of the asymmetric degree for the asymmetric-paths winding is proposed,to evaluate the actual harmonic content of the circulating current between parallel paths.In addition,according to the basis arrangement principles,the mathematical model for the arrangement optimization is built,and a solving method based on the improved discrete particle swarm algorithm is provided.Besides,based on the distribution feature of the asymmetric-paths windings,the distribution indices of the connections and corresponding calculation method are proposed.In addition,according to the basis connection principles,the mathematical model based on the directed graph for the connection optimization is built,as well as corresponding searching and matching methods are provided.Moreover,by comparing the corresponding performances among some arrangement and connection schemes,the proposed optimization design method can be validated.The rules with the coil-pitch change can also be concluded.The above studies provide a new direction for the design of similar windings.Secondly,the equivalent circuit model for the asymmetric-paths winding is built.Then,a novel frequency-domain method is provided to calculate the reactance parameters between slot-conductors,and a novel solving method based on the improved genetic algorithm is proposed.Besides,by analyzing the results for the electromagnetic force of typical slots,the distribution feature of the electromagnetic force are concluded.In addition,the novel criteria to evaluate the above force characteristic are given,which include the evaluation and distribution criteria of the total electromagnetic force,and corresponding calculation methods.Moreover,by comparing the results of circulating current and electromagnetic force,the proposed calculation methods,distribution features and evaluation criterions can be validated.In addition,the change rules of the circulating current and electromagnetic force are concluded.The above studies provide the theoretical basis for the similar designs.Finally,an improved calculation method of the transient parameters for the asymmetric-paths winding is proposed,and a novel fitting method based on the improved ant colony algorithm is provided.Then,the research on the calculation method of the steady parameters is carried out.In addition,the theoretical derivations for the calculation method of the zero-and negative-sequence parameters are provided.Besides,by comparing the corresponding results of schemes,the change rules for the steady and transient,zero-and negative-sequence parameters are concluded.The above studies provide the technical support for the similar problems.