Research And Development On Layered Active Equalization Technology Of Battery Pack Based On Inductor

Each battery in the new energy vehicle battery pack may have differences in battery capacity,internal resistance,and self-discharge rate.This difference is called battery inconsistency and may be detrimental to the available capacity and service life of the battery pack.In order to effectively reduce the adverse effects of battery inconsistency on the battery pack,it is necessary to study the equalization technique.In the active equalization topology of the battery pack,the equalization speed and the number of energy storage components are two key indicators that affect its performance.Based on the improvement and optimization of the inductor-based active equalization topology,this paper proposes two active equalization topologies for the above two key indicators.Firstly,in order to solve the problem that slow equalization speed of the traditional inductor-based equalization topology,an inductor-based layered equalization topology(IBLE)is proposed to.This topology is divided into upper and lower layers.Each equalization circuit includes multiple equalizers to form equalization sub-circuit,and different equalizers do not affect each other.Therefore,the topology has multiple equalization paths.Through the quantitative analysis of the equalization principle,the quantitative relationship between the value of the inductor and the switching frequency and the equalization current is obtained,and the maximum duty ratio of each equalizer is given.The simulation results show that this topology has a faster and more stable equalization speed compared to the traditional inductorbased equalization topology,and the equalization time is reduced by 14% compared to the Parallel Architecture Equalization topology(PAE).Then,in view of the problem that a large number of energy storage components of the traditional inductor-based equalization topology,an inductor-based novel layered equalization topology(IBNLE)is proposed.This topology is divided into upper and lower layers.Each equalization circuit adopts the structure that an equalizer corresponding to two battery units,in order to replace the conventional structure that an equalizer corresponding to one battery unit,so the topology has less number of the energy storage components.Through the quantitative analysis of the equalization principle,the quantitative relationship between the value of the inductor and the switching frequency and the equalization current is obtained,and the maximum duty ratio of each equalizer is given.The simulation results show that compared with the traditional inductive equalization topology,the topology can reduce the number of energy storage components while ensuring faster equalization speed,and the advantage of the number of energy storage components is more obvious when the number of series batteries is more.Finally,the battery pack active equalization experimental platform is built,and the equalization experiments were performed on the IBLE and the IBNLE,respectively.The experimental results show that both the IBLE and the IBNLE can effectively complete the active balancing of the battery pack,and the balance accuracy is high.The IBLE can achieve a large equalization current,and the equalization can be completed in a short time;the IBNLE has fewer energy storage components and can ensure a faster equalization speed.