An Uni-Directional Single-Phase Soft-Switched Resonant High Frequency Link Inverter

Renewable and alternate energy grid integration is an area of interest in the recent years due to the advancements made in Solar and Fuel Cells. This paper considers a single stage single phase uni-directional High-Frequency Transformer (HFT) link DC-AC converter for grid integration of Distributed Energy Resources (DER). The HFT helps by providing galvanic isolation to protect DER from single faults at significantly low cost and size in comparison with Low Frequency Transformer (LET). Resonant based power conversion in relatively high voltage DC-DC converters results in higher efficiency and power density. Soft switching due to device capacitances and HFT parasitic leakage inductances enables high frequency of operation. This paper presents a novel Parallel Resonant Converter (PRC) based control strategy that results in high quality adjustable frequency and amplitude AC and soft switching of all devices in the entire range of operation. A well-known single stage isolated inverter topology is slightly modified to incorporate PRC based operation. Simulation results are presented to validate the topology and proposed modulation scheme.