High-efficiency Maximum Power Tracking Method for Parallel PV Generation System Based on Push-Pull Converter

Introduction: This study addresses voltage mismatch issues in Parallel Photovoltaic (PV) modules, a critical concern in low-power PV generation systems. A voltage matching method is proposed to optimize power output and enhance overall system efficiency. Method: The research introduces a voltage matching principle, leveraging the transformer winding turns ratio within a push-pull converter. This approach, based on a constant voltage tracking algorithm combined with output voltage fluctuation compensation, ensures each PV module operates near its maximum power point. The proposed scheme was modeled and simulated using PLECS software. Results: Simulation results indicate that the proposed scheme achieves rapid maximum power point tracking for each parallel PV module, with an average overall system efficiency of up to 97.43%. Discussion: Comparative analysis reveals that while a buck converter with a perturbation and observation algorithm offers effective tracking, it fails to resolve voltage mismatch issues. Specifically, the system efficiency was only 58.65% when four PV modules were connected in parallel. The voltage matching principle improved efficiency to 96.36% by connecting two low-voltage PV modules in series and then connecting them in parallel with the other two PV modules, but the series connection of two PV modules has the problem of exceeding the safe operating voltage. Conclusion: The proposed multi-input push-pull converter scheme, incorporating a constant voltage tracking algorithm and voltage fluctuation compensation, effectively matches the maximum operating voltage of parallel PV modules. This approach enables maximum power point tracking under various irradiance conditions and improves the overall average efficiency of the PV generation system.