A Synchronous-Buck Converter with an MPPT Application for Photovoltaic Battery Charging Systems

A synchronous-Buck converter is proposed as part of a maximum power point tracking (MPPT) controller for charging a 12 V battery from a photovoltaic (PV) solar panel. This design incorporates a control module that manages energy flow from the solar panel to the battery. The novel module sequentially integrates MPPT, active current limiting (constant current, CC), and voltage regulation (constant voltage, CV), along with protection mechanisms and low-computational-complexity control. It also incorporates a synchronous-Buck converter with a current PI control loop; this differs from the strategy used in a traditional Buck converter in terms of how much switching losses are reduced. The proposal integrates these two stages and establishes a robust control scheme that enables the battery charging process in photovoltaic systems to adapt to variations in both input and output conditions. Additionally, an irradiance detection logic has been incorporated to ensure that the system operates only when there is sufficient solar radiation is available, thereby extending the system’s lifetime and improving overall energy utilization. This work focuses on the practical integration and experimental validation of a comprehensive maximum-power-point-tracking (MPPT)-based charging system. The main contributions of this study can be summarized as follows: (1) practical integration; (2) experimental validation; (3) hardware-based protection strategy and low-computational-complexity control. To validate the designed system, a 70 W prototype with 90% efficiency was implemented and tested. The experimental results verify that the implemented protection mechanism prevents the battery from discharging unnecessarily during low-irradiance or nighttime conditions. This improves the overall efficiency of the system and extends the battery’s lifetime.