Rectifier Synchronous Generator Electromagnetic Analysis

Rectified synchronous generator has been applied more and more widely in many fields. The research of the rectified synchronous generator has gradually been deeper.In this paper, based on the finite element theory and the finite element software Ansys, electromagnetic analysis and parameter calculation has been given to the rectified synchronous generator.This paper firstly introduces the research background and the research status at home and abroad. And then introduces the basic theory of the electromagnetic field, the principle and the implementation steps of the finite element method. Considering the condition of this research, the application of coupling and constraint equation is highlighted when Ansys software is introduced.The bridge rectifier circuit is implemented in Ansys software. In the nonlinear calculation caused by diode, a series of factors for convergence such as the load step, the iteration number and unit characteristics are analysed. Reasonable load step or number of iterations would help convergence. Parameters of diode have an important influence on the convergence. This situation is more obvious in the polyphase circuit.Coupling in Ansys can be divided into two kinds:direct coupling and indirect coupling. The two ways have their own advantages and applicable occasions. In the process of modeling rectified motor, to consider the effect of nonlinear component diode to the motor system electromagnetic field, direct coupling method is chosen for modeling. In the coupling process, different unit is used and unit characteristics are selected flexibly to simulate various parts of the motor.Time stepping finite element method is used to analyse the motor transient behavior. The deputy of the time stepping finite element method-moving boundary method and virtual node displacement method are then analysed. In the calculation of rectified motor by direct coupling method, nonlinear diode affects the linear matrix of circuit unit. At this time constraint equations should be imposed between nodes and units, and moving boundary method should be chosen for transient analysis.Loss calculation is an important part of motor parameters calculation. In the calculation of loss of the rectified motor, to avoid air gap node to be meshed too dense, sequential coupling method is used for solving. The circuit part directly coupled is removed, the winding current is interpolated and imposed to the finite element model as "face load". In the process of solving, time step finite element method is also needed. Because nolinear diode is removed at this time, virtual node displacement method is a more convenient and practical choice.