Analysis of Cell Balancing to improve Performance and Life Expectancy for Lithium Ion Energy Storage Systems

摘要

Lithium-ion batteries are more and more gaining importance in automotive industry. Battery packs for hybrid electric vehicles (HEV) consist of more than 100 cells in series. Lithium-ion batteries in particular require cell voltages to be strictly kept in boundaries to ensure safe operation. Therefore power performance is always limited by the first cell which goes beyond the boundaries. Production deviations from cell to cell and inhomogeneous ageing and temperature within the pack result in imbalances. States of charge (SOC), capacities and internal resistances will deviate.