Polyphase Synchronous Generator Electromagnetic Field Analysis

The design and application of multiphase synchronous generator is the front task of motor field. Multiphase synchronous generator commutate system is broadly used in most sites which need high quality DC power supply. Based on the electromagnetics theory, the paper makes an electromagnetic analysis of a six-phase synchronous generator with double-Y30°-deflected winding using finite element method.Firstly this paper introduces the background the of the task and study status at home and abroad. The article introduces the winding distribution of six-phase synchronous generator with double-Y30°-deflected winding and the composed first-harmonic magnetic motive force of the six phase winding. Synchronously, it indicates the advantages of the six-phase synchronous generator with double-Y30°-deflected winding compared with the traditional three phase synchronous generator.Secondly this paper introduces the basic theory of the electromagnetic and characteristics of the finite element method. According to the parameter of the six phase motor, the2D simplified model is established. The no-load field current and short circuit field current of the six phase synchronous generator are calculated using Ansys and Ansoft software, the results are verified using different methods. Using Ansys software, the field current under rated load is gotten by terminal voltage iteration and power factor iteration.By performing electromagnetic analysis, the six phase motor’s parameter such as the direct-axis reactance of armature reaction, the direct-axis transient reactance and the direct-axis sub-transient reactance are obtained. The coupled field-circuit method is used to calculate the direct-axis transient reactance and the direct-axis sub-transient reactance. The end winding leakage reactance of the field-winding is taken into consideration.The time stepping finite element method with coupled field-circuit analysis is carried out to emulate the short circuit of the six phase generator commutate system under no-load circumstance. The short circuit current peak value of the DC site and AC site is obtained when the rectifier bridge is connected in line and in parallel. The results provides reasons for protection selecting.The work of this paper is of great value in multiphase synchronous generator design and optimization.