Analysis of self-excitation and performance characteristics of a single-phase self-excited induction generator by field-circuit method

Abstract

Purpose – The purpose of this paper is to present analysis of an influence of rotor slots opening on self-excitation process, terminal voltage and performance characteristics of the single-phase self-excited induction generator (SPSEIG). Design/methodology/approach – The paper presents field analysis of the self-excitation problem in the SPSEIG and performance characteristics on the base of two-dimensional field-circuit model of the generator. Findings – The carried out field computations of the tested SPSEIG with closed rotor slots showed that only an initial voltage across the excitation capacitor of about nominal value (230 V) causes successful self-excitation of the generator. It was also proved that the suitable opening of the rotor slots, beside remnant flux density in the rotor core, facilitates self-excitation in the generator. Since in working applications initially charging of the capacitor to almost nominal voltage may cause a problem, therefore employment of semi-closed rotor slots in the SPSEIG would be proper solution. Originality/value – The conducted simulations, validated by laboratory tests showed that not only suitable excitation capacitor capacitance and rotor speed are needed to obtain desired terminal voltage of the generator, but also suitable initial voltage across the capacitor in auxiliary stator winding is very important and necessary for reliable self-excitation of the single-phase induction generator with closed rotor slots. The employment of semi-closed rotor slots in the SPSEIG makes the self-excitation more effective.