A photovoltaic (PV)-based generator is a crucial component of modern electricity grids. Most PV systems utilize various maximum power point tracking (MPPT) algorithms to inject the maximum available power into the utility. However, on sunny days, consistently obtaining maximum power can lead to increased thermal stress and a reduced reliability of the power electronic-based DC-DC converter. This paper presents a thermal model for the DC-DC converter that evaluates the accumulated temperature based on power losses and ambient temperature sensed by the thermal sensor. A thermal control strategy is suggested to maintain the temperature of the converter's main components within allowable limits. The thermal control includes two stages: a primary stage that adjusts the switching frequency of the IGBT switches to decrease the accumulated temperature and a secondary stage that adjusts the current-based MPPT algorithm to reduce the maximum current through the main switch. This approach aims to extend the lifespan of the utilized DC-DC converter and lower its operational cost. Furthermore, the allowable range for switching frequency variation is determined through a stability analysis of the frequency response, which is evaluated using a Bode plot for the closed-loop system. The proposed thermal control was implemented in a MATLAB/Simulink environment. The associated results demonstrate the effectiveness of the proposed control in maintaining temperature within acceptable limits and thereby improving the reliability of the system.

Li-ion batteries can be charged with different techniques according to the charging time and required capacity usage. Most charging techniques face difficulties when implemented in PV systems due to the intermittent and unpredictable nature of the power supply. This paper addresses the issue of determining the appropriate charging technique for Li-ion batteries in a PV system. We have developed a mode-selective control approach that determines the optimal charging mode according to the given SOC and solar irradiation, aiming to maximize the utilization of the generated PV power. The developed control approach has been implemented using a dual-switched buck converter in the MATLAB/Simulink environment. The key control algorithm focused on regulating current, with different references being used based on the selected charging mode. Three references for charging current were set: the maximum current, the required current assigned based on the given SOC, and the pulsed current. The pulsed current reference was employed during a stage of the charging process to accelerate charging and prevent dissipation of PV power. Furthermore, a gain-scheduled controller with carefully picked control parameters was used to ensure stable operation across different modes. The results proved the effectiveness of the proposed control in reducing charging time and minimizing PV power dissipation without resorting to the use of harmful charging currents.