Double-Tiered Cell Balancing System With Switched-Capacitor and Switched-Inductor

By considering the impact of parasitic resistance of inductors and capacitors employed in buck-boost and switched-capacitor types of cell balancing systems, a double-tiered cell equalizer is developed in this work. The first tier of this system is derived from buck-boost cell equalizer and the second tier is implemented by a switched-capacitor equalizer which has fast equalizing speed. The two tiers share a common switch array controlled by one pair of complementary square wave signals. The number of switches is therefore reduced significantly and there is no voltage nor current signals needing to be sensed for complex close-loop control. Circuit configuration, modeling and design considerations are illustrated in detail. Both simulation and experimental results are provided to demonstrate the feasibility of the proposed cell balancing system.