A hardware efficient lithium-ion cell balancing technique utilizing low-volume hybrid DC-DC converter

This paper introduces a novel battery cell balancing technique for portable applications, where multiple series connected lithium-ion battery cells are utilized. The equal discharge of the battery cells are achieved through a simple modification of a hybrid step-down dc-dc converter, where only an additional resonant inductor is required. Hybrid converters, combining switched-capacitor and inductor based topologies, are gaining popularity in battery powered portable applications due to their attractive features, such as improvement in efficiency and reduction in passive output filter components, compared to a conventional step-down buck converter. By inserting a resonant inductance between the stacked battery cells, equal discharge of multiple cells are provided. The experimental results show the effectiveness of the introduced cell balancing technique in a 98.1 % Efficiency 5W (@5V, 1A Output) hybrid step-down dc-dc converter.