Analysis and control of self-excited induction generator-converter systems for battery charging applications

A method has been developed for the analysis of operation of self-excited induction generators (SEIGs) supplying battery charging loads through three-phase semi-converters by representing the battery circuit as equivalent resistance and reactance in the equivalent circuit of these generators. Such equivalent values are functions of the dc charging voltage and current and the control angle set in the converter. The solution for this circuit has been carried out using the genetic algorithm technique instead of using higher-order polynomials for the loop or nodal equations of the circuit. Apart from the conventional phase angle control, other firing control schemes namely negative firing angle control, extinction angle control and symmetrical angle control have been considered for the operation of the converter. The relative performance of these control schemes, for the various modes of operation of SEIG-converter systems such as constant and variable speed, has been brought out. Experimental results obtained on a three-phase SEIG charging suitable batteries through an IGBT-based semi-converter, controlled with all these schemes, confirm the usefulness of the proposed system and the validity of its analysis.