A novel low-loss commutation circuit for bridge-type power converters is presented and analyzed. Experimental measurement results are given. With relatively low effort, soft switching (zero voltage, zero current switching) is achieved from no load to full load. Low RMS current stress, no voltage stress beyond the DC link voltage and very low switching stress of the additional circuit devices are present. The two auxiliary switches only have to turn on and off a low magnetizing current. No additional limiting and damping circuits, voltage sources and energy return switch mode power supplies are necessary. The design is extremely simple using half-bridge modules. The circuit has been developed for a DC-DC power converter, consisting of two IGBT half-bridge modules but moreover it is suited as snubber for IGBTs and GTOs in high power, high frequency converters, UPS and electric drives application.
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