Passive snubber energy recovery for a GTO thyristor inverter bridge leg

This paper presents a turn-on and turn-off passive energy recovery snubber circuit suitable for high-voltage high-power gateturn-off thyristor inverter bridge configurations. The circuit recovers not only inductive turn-on and capacitive turn-off snubber energies, but also energies associated with freewheel diode reverse recovery. Energy is transferred back to the DC supply via a high-frequency transformer, that is fully reset. A method for reducing the transformer secondary diode voltage stress is presented. The performance of the circuit is supported by PSpice simulation, mathematical analysis, and practical results.