Comparative Study Between the Ćuk and the LLC Converter in Photovoltaic Applications

This paper presents a power electronic circuit topology comparison enabling the optimization of photovoltaic power conversion systems. It considers the trend of differential power processing (DPP), which is one solution to mitigate aging-related mismatches limiting photovoltaic-based energy systems. In order to balance currents in these advanced DPP architectures, included DC-DC converters must bidirectionally transfer power and have unity conversion ratios with input-output isolation. This paper focuses on Ćuk and the resonant LLC circuit topologies, which fulfill these requirements. In this report, these two circuit topologies have been comparatively studied considering key variables such as cost, efficiency, simplicity of control, reliability, and practical realization. Finally, in a 15 W case study, simulation and experimental results indicate that the LLC converter can provide efficiency above 90% at very low power while the Ćuk converter can provide better efficiency at higher power levels.