Abstract
Most series battery active equalization circuits implement the equalization first within the series and then between the series, which restricts the equilibrium speed. A hierarchical equalization circuit topology based on the Buck-Boost module is applied in this paper. The equalization is divided into two different equalization processes according to the equilibrium energy flow. The two equalization processes can be performed simultaneously, and the currents in the different hierarchical circuits do not affect each other, thus achieving simultaneous equalizations within the series and between the series. An equalization condition of the terminal voltage is applied and simulations and experiments on charge, discharge, and static equalizations in the four series-connected ternary lithium-ion batteries are performed.
Highlights
Lithium-ion batteries have been widely used in electric vehicle energy storage systems owing to their high energy density, no memory effect, and long cycle life [1]
In an energy storage system in which the multi-cell battery is connected in series, the battery may overcharge and over-discharge during the charging and discharging processes of the series power battery pack owing to the inconsistency of the cells
An active hierarchical equalization circuit topology was used in a series battery pack
Summary
Lithium-ion batteries have been widely used in electric vehicle energy storage systems owing to their high energy density, no memory effect, and long cycle life [1]. A discrete time quasi-sliding mode-based strategy utilizing the saturated equalization current was proposed, which enabled the converters to operate together effectively to achieve single SOC equalization. Several researches have been performed on equalization control algorithm and adequate equalization effect has been achieved, it often fails to meet the requirements for the equilibrium speed in engineering applications. To this end, this paper implements a converter-based equalization method for active equalization. Based on the buck-boost active stratified equalization circuit, a control strategy for simultaneous equalizations within and between the packs is proposed, which realizes the charging, discharging, and static operations of the battery pack. The energy equalizations in the three states are set to achieve continuous and controllable energy of the series battery pack, thereby accelerating the equilibrium speed of the battery pack
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
