Actuation apparatus and actuation method for an active snubber circuit for a DC-DC converter

A DC-DC converter comprising:

• a first output and a second output;
• a transformer having a primary-side winding and a secondary-side winding with a center tap and end taps;
• a storage choke coupled between the center tap and the first output;
• a rectifier circuit connected to each of the end taps of the secondary-side winding and designed to generate a rectified output voltage at the second output;
• a snubber circuit switched via the rectifier circuit and designed to store resonant oscillation energy occurring in the rectifier circuit;
• and
• an actuation apparatus including
• a switching time determining device designed to determine a time interval as a function of the rectified output voltage, the charge stored in the snubber circuit and the current fluctuations of the current through the storage choke occurring as a result of the rectification;
• and
• a control signal generator designed to generate an actuation signal for discharging the snubber circuit as a function of the determined time interval,
• wherein the snubber circuit includes a charge collection device designed to store the resonant oscillation energy occurring in the rectifier circuit as charge, and a discharge circuit, which is designed to selectively discharge the charge stored in the charge collection device,
• wherein the charge collection device includes
• two diodes, each coupled to the taps at the ends of the secondary-side winding of the transformer;
• and
• a snubber capacitor coupled to the two diodes and designed to store the oscillation energy as charge, and
• wherein the discharge circuit is a buck converter, which includes
• an inductor designed to feed the charge stored in the snubber capacitor back into the first output of the DC-DC converter;
• and
• a discharge switch coupled between the snubber capacitor and the inductor and designed to selectively connect said snubber capacitor to said inductor as a function of the actuation signal.