A New Cell Balancing Architecture for Li-ion Battery Packs Based on Cell Redundancy

Abstract

Li-ion batteries are promoting the development of more and more performing electric vehicles (EVs) and hybrid EVs (HEVs). Thanks to their high energy density and increased current capabilitieswhich permit to use a relative light and space saving battery pack-these batteries are replacing almost all older battery chemistries in vehicle applications. Despite the advantages these cells provide, before use them in a new design, several drawbacks about safety aspects have to be considered. In fact, Li-ion battery packs require, more than other chemistry base packs, special control systems to maintain the operative conditions in a safe area and to guarantee the best performances in terms of efficiency and pack life time. One of the most challenging problems that have to be tackled by the mentioned control system is the voltage unbalance. This problem arises when more cells are connected in series with the purpose to increase the battery pack voltage. In this paper a new cell balancing architecture based on cell redundancy is proposed. This solution is especially suited to be implemented in vehicle battery management system (BMS) where cost and space reduction are the main requirements.

Semi-Empirical Capacity Fading Model for SoH Estimation of Li-Ion Batteries

“…An interesting observation from our experiments is that batteries tested for a similar number of cycles under the same stress conditions show a difference in SoH drop, which signifies variation among the batteries. This could be due to the different imbalance in the internal state for an individual battery [25]. This renders it difficult to estimate single battery life, but users need to know the degradation of each of their batteries, instead of the entire population of batteries.…”

Development of a New Battery Management System for Maximizing Battery Performance

“…Most common method of passive balancing is charge shuttling in which additional load (Resistor) is connected in parallel across each cell. Extra charge is dissipated in the form of heat through the shunt resistor connected in the parallel to the battery cell [24]. It cannot be used for lithium-based batteries as there is a high risk of explosion [25].…”

A comprehensive review on inconsistency and equalization technology of lithium‐ion battery for electric vehicles

“…TBBCs have high equalization current and high efficiency, but the manufacture of transformers with symmetrical windings is quite difficult. PBBCs such as buck‐boost converters and Cuk converters have attracted much attention due to their high balancing efficiency and easy integration, but the cost and the complex control strategy are their shortcomings 119 . New topologies such as hierarchical structure can reduce equalization loss and balancing times, but still require more verification.…”