DIRECT-PHASE MODELING OF ISOLATED BRUSHLESS EXCITER-ALTERNATOR UNIT INCLUDING THE MAGNETIC NONLINEARITIES

Detailed accurate models for brushless alternator units are important for practice and design engineers. The paper presents a state space ma thematical model for a standalone unit based on a circuit model in the direct-phase reference frame. Also, a state space mathematical model for an automatic voltage regulator is integrated with the machine mode l. Due to the existence of the rotating bridge rectifier of the excite r, the topology of the circuit is variable. Therefore, Kron's tenser t echnique is applied using a variable connection matrix to develop the mathematical model. The model is complete in the sense that it covers all modes of operation of the bridge rectifier. Consequently, it is ca pable of simulating any loading conditions. To enhance the model accur acy, electromagnetic nonlinearity effects are introduced through devel oped saturation factors which consider the mutual saturation effects b etween the main and leakage fluxes. Also, a new saturation concept usi ng dynamic and static inductances is applied. Various transient respon ses are computed and compared with test results to verify the validity of the presented model.