The Feasibility Study of Single-Stage LLC Resonant Converter for Photovoltaic DC Microgrids

In conventional photovoltaic (PV) DC boost systems, a dual-stage DC-DC configuration is typically employed. This paper introduces a single-stage DC-DC architecture that combines the photovoltaic module with an LLC resonant converter. Addressing the issue of the wide variation in the output voltage of the photovoltaic module, which results in a large input voltage range for the LLC converter and hinders the transmission of the maximum output power, this paper introduces a method for verifying work characteristic matching. Through theoretical derivation, the P-V characteristic curve of the LLC converter is obtained when the photovoltaic module is used as the input. At different switching frequencies, the P-V characteristic curve of the LLC converter covers various power ranges. The method verifies whether the range of the characteristic curve, adjusted by changing the switching frequency, can encompass the maximum power point of the photovoltaic module. Based on the results of the simulation, the proposed work characteristic matching method effectively validates the feasibility of transferring the maximum power from the photovoltaic module under varying output voltage conditions, with the photovoltaic module integrated with the LLC resonant converter.