A SEPIC-Ćuk derived hybrid converter with single-input inductor and dual DC/AC outputs for microgrid applications

Abstract

As load profiles continue to shift toward a hybrid mix of AC and DC, microgrids increasingly require cost-effective converters capable of powering both AC and DC loads simultaneously. However, existing converter topologies often exhibit limitations including inadequate voltage gain, high switching stress, complex control schemes, and reliability challenges. To address these challenges, this paper proposes a novel SEPIC-Ćuk Derived Hybrid Converter (SCDHC), integrating SEPIC and Ćuk converters utilizing a single, shared input inductor and replacing the conventional control switch with a single-phase voltage-source inverter (VSI). This design achieves double the DC voltage gain compared to conventional SEPIC, Ćuk, or SEPIC/Ćuk-based hybrid converters, while exhibiting lower switching stress, and inherently provides shoot-through protection for the AC output, significantly enhancing reliability while reducing the required number of control switches. A modified unipolar sinusoidal pulse width modulation (SPWM) strategy is adopted to regulate power flow, while a memory-efficient switching scheme, implemented by Verilog HDL on an FPGA, ensures precise gate pulse generation. The converter’s steady-state behavior, cross-regulation performance, and dynamic response under step load changes are thoroughly analyzed. Experimental validation using an 80 W laboratory prototype substantiates the SCDHC’s ability to maintain stable and regulated DC and AC outputs under varying load conditions. Comparative evaluations demonstrate the proposed converter’s superiority over existing topologies in terms of voltage gain, efficiency, component count, reliability, switching stress, and control complexity, highlighting its suitability for residential microgrid applications requiring simultaneous DC and AC power delivery from a single DC source.