Composite control strategy for wide-gain LLC resonant converters with photovoltaic energy storage inputs

Taking the photovoltaic-battery dual-input LLC resonant converter as the focal point of research, a mode-switching switch is incorporated to address the narrow range of voltage regulation in frequency conversion control. A wide-gain composite control strategy, with combined frequency conversion control and variable-mode control, is proposed. The variable mode control facilitates switching between the different operational modes of the converter, allowing for the regulation of the output power of the load while expanding the voltage regulation range. However, variable mode control can result in significant ripple in the output voltage. As an auxiliary voltage regulation method, variable frequency control is used with variable mode control to reduce ripple. Based on the wide gain composite control strategy, the implementation conditions of soft switching in wide gain LLC resonant converters are analyzed in detail to improve converter efficiency. Finally, the feasibility and effectiveness of the proposed composite control strategy are validated through rigorous experiments.