Switching power supply system and process

A control process for controlling a switching power supply system comprising a semiconductor switching device for periodically opening and closing a circuit for supplying power from a dc power source to a load, an inductive component connected in series with the switching device, a capacitive component connected across the switching device, a series combination of a first diode and a voltage clamp which are connected in series with each other, the series combination being connected in parallel to one of the switching device and the inductive component, and a control circuit for controlling the switching device, the control process comprising:

• a first step for transferring energy stored in the inductive component during an on period of the semiconductor switching device, to the voltage clamp during an off period of the switching device by utilizing forward conduction of the first diode;
• a second step for returning most of the energy stored in the voltage clamp through the inductive component to the dc power source by reverse conduction of the first diode;
• and
• a third step for turning on the semiconductor switching device after the second step, a switching period of the semiconductor switching device being shorter than a carrier lifetime of the first diode.