Transfer Function Model of a Brushless Exciter

Brushless exciters are widely used in power stations to furnish the excitation current for the main alternators. These exciters are maintenance free and possess high gain and forcing margin. Transfer function models available for such exciters are somewhat complicated and deal with few variables. The objective of this paper is to develop a detailed transfer function model relating all the important exciter variables and covering the operation in a wide range of frequency. Starting with a state space mathematical model based upon a direct-phase circuit model for the exciter, various frequency responses are obtained. These are used to derive the transfer function model.