Abstract: A multi-voltage switching power supply having a first pair of switches connected in series with each other across a pair of incoming power lines. The switches are alternately closed at a fifty percent duty cycle. A plurality of pairs of series-connected switches are also connected between the incoming power lines and operated in a pulse-width modulated mode. Power supply circuits are connected between the junction of the pulse-width modulated switches of each pair and the junction of the fifty percent duty cycle switches. The peak value of the current applied to the power supply circuit, which determines the power supply output voltage, is controlled by adjusting the closure time of the pulse-width modulated switches.

Abstract: A boost power supply having a full-wave rectifier driving an inductor, diode, and the parallel combination of a filter capacitor and load. A shunting switch connected between the inductor and diode is periodically closed to draw current through the inductor, thereby charging the inductor. The switch is then opened so that the inductor, while discharging, generates a relatively high voltage which is applied to the load and filter capacitor through the diode. The shunting switch is opened and closed in a manner which causes the input current to follow a sinusoidal waveform in phase with the input voltage with an amplitude that maintains the output voltage of the power supply constant. Specifically, a harmonically pure sinusoidal waveform is multiplied by a voltage inversely proportional to the output voltage.