Study of voltage build up in a self-excited, variable speed induction generator/static inverter system with DC side capacitor

The paper gives a mathematical analysis of the voltage build up of an induction generator, self-excited by a DC side capacitor connected through a modulated inverter. The load is assumed to be connected across the capacitor. The effect of variables like load resistance, capacitor value, slip and modulation index on the process of build up is studied. It is shown that the value of the capacitor affects the rate of build up and the steady-state ripple voltage across the load. Also a minimum value of the capacitance is needed for self-excitation. The results of the analysis clearly indicate that it is possible to maintain constant DC voltage over a wide range of prime-mover speeds and loads by controlling the inverter frequency and the modulation index without changing the capacitor value.