Design and Analysis of Multi-Input SEPIC DC-DC Converter for UAVs Charging Applications

The Single Ended Primary Inductor Converter (SEPIC) is a DC-DC converter capable of providing two operation modes (buck and boost) while keeping the polarity of the output voltage same. The buck and boost modes of operation are achieved by changing the duty ratio below and over 0.5. Due to its advantage of having a wide input voltage range, these converters will be beneficial to use for solar charger applications. However, the power from solar source is variable as it depends on weather conditions, but for charging applications power demand should be fulfilled to retain proper charging operation. In order to tackle the problem addressed, a multi-input SEPIC (MISEPIC) converter is proposed in this paper to overcome the constraints of traditional single-input SEPIC converters. The proposed converter improves power efficiency and operational flexibility, making it a viable solution for renewable energy-based charging applications. The proposed converter consists of two switches, as seen in Fig. 1. The first switch is responsible for harnessing the maximum power from PV panels by tracking the maximum power point (MPP). The second switch is used to regulate the desired output power, by harnessing power from the second power source, whenever the power from solar is not sufficient. The mathematical modeling, modes of operation and proposal of control logic for the proposed converter have been carried out in this paper. The effectiveness of the proposed converter and its control strategy is assessed through simulation performed in MATLAB R2023b. The results indicate that the MI-SEPIC converter offers superior efficiency, improved load regulation, and increased adaptability compared to conventional SEPIC designs. These advancements contribute to the development of charging applications for UAVs, EVs, etc.