Abstract: A low dissipation snubber for switching power transistors uses the energy stored in a snubber capacitor to provide all the base boost power required for switching the power transistors on. The snubber consists of a diode and a snubber capacitor connected in series between the collector and emitter of the switching transistors with a resistor connected at one end to the junction of the diode and the snubber capacitor. The other end of the resistor is connected to the base turn-on circuit for the switching power transistors so as to provide a discharge path for the snubber capacitor. By using the discharge of the snubber capacitor, power which is normally dissipated as heat is reclaimed so that the drive power requirements for the switching power transistors are reduced.

Abstract: A saturable reactor snubber to improve the recovery characteristics of a clamp diode used in a power switching circuit is provided with a secondary winding to permit saturating the reactor via a secondary current pulse in order to improve the turn-on speed of the clamp diode. The current pulse for saturating the reactor at turn-on is preferably derived from a shunt snubber charging pulse or from an external generator synchronized to the turn-off time of a power switching device in the switching circuit.