Non-dissipative LC snubber circuit

Claim 1

In a non-dissipative snubber circuit adapted for use in a power switching circuit of the type including a source of D.C. voltage, at least one controlled switch, a main inductance connected directly to said switch adapted to protect said switch during closure thereof, a load having a free wheel diode associated therewith, said switch, main inductance and load being connected in series across said source, and a capacitor adapted to protect said switch during opening thereof, the improvement comprising a branch circuit including said capacitor, a first diode and an auxiliary inductance in series, mounted in parallel across said switch, with a first terminal of said capacitor connected directly to the junction of said controlled switch and said main inductance; a second diode connected between the second terminal of said capacitor and a point of substantially fixed potential provided by means associated with said voltage source, said fixed potential being higher or lower than the potential applied to the end of said controlled switch opposite said main inductance, according to whether said latter potential is negative or positive respectively; said first and second diodes being poled to be blocking with respect to the D.C. voltage applied by said source to the branch circuit including said diodes and said auxiliary inductance in series.