An energy-feedback clamping circuit of a power converter is proposed. The converter includes a transformer coupled to a full-wave rectifier circuit. The clamping circuit includes: two clamping diodes having two anodes coupled to each other at a common-anode terminal and two cathodes coupled to two terminals of a secondary winding of the transformer, a first clamping capacitor having a first terminal coupled to a cathode of a first rectifying diode of the rectifier circuit and a second terminal coupled to the common-anode terminal, a second clamping capacitor having a first terminal coupled to a connecting node of the output filtering inductor and capacitor of the rectifier circuit and a second terminal coupled to the common-anode terminal, and a converter circuit having an input terminal coupled to the second clamping capacitor and an output terminal for offering a power source.
Provided is a flyback DC/DC converter for a power supply. In the flyback DC/DC converter, a flyback driver unit provides a primary current. A transformer includes a plurality of secondary coils for inducing energy from the primary coil receiving the primary current. A rectifier unit includes a plurality of rectifier diodes for rectifying secondary currents of the corresponding secondary coils of the transformer. A plurality of clamp diodes are connected in series to the corresponding rectifier diodes of the rectifier unit in a forward direction to clamp ringing voltage across the corresponding rectifier diodes when the power switch is turned off. Accordingly, the voltage across the rectifier diode on the secondary side can be reduced such that it is lower than the output voltage. Also, it is possible to remove the ringing voltage of the rectifier diode and to enhance the efficiency of the flyback DC/DC converter.
