Master of Science in Engineering, University of Akron, 2014, Electrical Engineering

An investigation into battery management for lithium-based battery packs was performed. Out of the investigation of the various management/balancing methodologies came a proposed management methodology that is integrated with a charging system and utilizes cost-effective, lossy, bypass resistors for cell balancing. This integration allows the management system to cater the charging current to the needs of the battery pack and overcome the limitations of the lossy bypass on its own. To first investigate this concept, a LiFePO4 cell model was obtained. This was done using a cell discharging procedure and characterization process that provides a mathematical first-principles cell model. The obtained model was then used to simulate various pack configurations, battery management configurations, including the proposed management method. The results from these simulations demonstrated that the proposed management methodology balanced cell voltages within a battery pack in as little as a single charge cycle. To confirm this concept a manually hand-controlled experiment, consisting of voltmeter monitoring cell voltages, manual activation of lossy bypass resistors, and manual adjustments of charging current, was performed. The results from this experiment confirmed the ability to balance the cell voltages within a single cycle. Hardware and software was developed to automate the proposed management methodology. Data collected from the automated implementation was in agreement with the performed simulations and successfully demonstrated a functional automated version of the proposed integrated battery management system and charger.

Committee: Tom T. Hartley Dr. (Advisor); Seungdeog Choi Dr. (Committee Member); Yilmaz Sozer Dr. (Committee Member) Subjects: Electrical Engineering