Low switching loss transistor regulated DC power supply - uses shunt transistor to establish current in inductor in series with output capacitor leaving no transistor current during switching

摘要

Direct current is obtained by rectifying an AC voltage. A positive DC rectifier terminal is connected, through a charging inductor, to a diode supplying an accumulator inductor in series with the accumulator capacitor, and also to a shunt transistor connected across the supply. The transistor provides a path for DC to flow from the rectifier through the charging inductor when switched on. The voltage developed over a resistor in the accumulator circuit drives a controller via a delay circuit. The control circuit drives the base of the transistor which, when it switches off, forces the charging inductor current to be directed to the accumulator capacitor. The controller prevents the switching of the transistor until the charging inductor current has fallen to zero. In this way the transistor carries no current during switching and the switching losses are minimal.