A multiple switch high-voltage DC-DC converter

A high-voltage DC-DC power converter with multiple series-connected devices is proposed. Series connection of power devices has evolved into a mature technique and is widely applied in HVDC systems. Static and dynamic voltage balance is ensured by shunting individual devices with (dissipative) snubbers. The snubber losses become pronounced for increased operating frequencies and adversely affect power density. Capacitive snubbers do not exhibit these disadvantages but they prerequisite zero-voltage switching mode. Super-resonant power converters facilitate the principle of zero-voltage switching. Furthermore they allow the application of nondissipating snubbers to assist the voltage sharing between the multiple series-connected devices and to lower turn-off losses. Simulation results obtained with a circuit simulator are validated in an experimental converter. The behaviour of the series connection will be examined for MOSFETs and IGBTs by both experimental work with a 1 kW prototype and computer simulation.