Soft-Switching Single-Phase Grid-Connecting Converter Using DCM Operation and a Turn-Off Snubber Capacitor

This paper proposes a new single-phase dc/ac converter topology with soft-switching operation. The proposed converter achieves soft-switching by using DCM (discontinuous current mode) operation and a common turn-off snubber capacitor connected to the dc terminals of a full-bridge configuration. One additional semiconductor switch is used to disconnect the snubber capacitor from the dc side, and allows the snubber capacitor to be discharged. The DCM operation realizes zero-current turn-on and the snubber capacitor achieves zero-voltage turn-off. The proposed converter can be applied to a grid-connected converter for domestic renewable energy and energy storage, including Photovoltaic and battery energy storage devices. This paper describes operation principles, control and modulation techniques as a grid-connecting converter. Experimental verification including loss analysis with a 1-kW pilot device is provided.