College - Author 1
College of Engineering
Department - Author 1
Electrical Engineering Department
Degree Name - Author 1
BS in Electrical Engineering
College - Author 2
College of Engineering
Department - Author 2
Electrical Engineering Department
Degree - Author 2
BS in Electrical Engineering
College - Author 3
College of Engineering
Department - Author 3
Electrical Engineering Department
Degree - Author 3
BS in Electrical Engineering
College - Author 4
College of Engineering
Department - Author 4
Electrical Engineering Department
Degree - Author 4
BS in Electrical Engineering
Date
6-2026
Primary Advisor
Taufik, College of Engineering, Electrical Engineering Department
Abstract/Summary
This project presents the design, simulation, implementation, and testing of a bidirectional buck–boost DC–DC battery charging system intended for an electric vehicle (EV) wind energy harvesting application. The objective was to develop a power conversion stage capable of efficiently charging a lithium-ion battery pack from the variable voltage output of a wind turbine generator while supporting a broader effort to extend EV driving range through renewable energy capture. The system consists of a load-dump protection circuit, a bidirectional buck–boost converter based on the Texas Instruments BQ25756 controller, and a 42 V 10-series-cell lithium-ion battery pack with an integrated battery management system (BMS). Design requirements included operation over an input voltage range of 25–55 V and delivery of up to 42 V and 4.1 A to the battery.
Circuit simulations verified the functionality of the load-dump protection and converter designs prior to hardware implementation. Experimental testing demonstrated successful converter operation in boost mode with efficiencies ranging from approximately 95% to 96.7%. Battery charge and discharge testing confirmed stable operation, effective battery management, and consistent cell balancing across all operating conditions. However, hardware limitations in the selected MOSFETs prevented reliable buck-mode operation, and testing revealed weaknesses in the load-dump gate-drive design. Despite these challenges, the project successfully demonstrated the feasibility of charging a lithium-ion battery from a variable-voltage renewable energy source and identified key design improvements for future iterations. The results provide a foundation for integrating renewable energy harvesting and battery charging technologies into future electric vehicle systems.
URL: https://digitalcommons.calpoly.edu/eesp/716