Active and passive equalisation topologies for lithium-type batteries

This Ph.D. focuses on the battery management system for small to medium electric vehicles. In electric vehicles, batteries might be more than 50% of the total cost, and hence the lifetime is important. The idea is to increase the lifetime of the battery as well as possibly the BMS itself. Mainly inductive battery management system variants are proposed. In general, manufacturing tolerances result in variations of the battery capacitance and internal resistance from cell to cell. These unavoidable differences are due to the chemical and electrical characteristics, such as asymmetrical degradation with aging, production tolerance, internal impedance. During past decades, many battery equalizers have been proposed in the literature. In this thesis, different types of active balancing techniques are investigated. The main objective of this dissertation is to focus on diverse inductive converter balancing techniques using inductors, transformers and coupled inductors. The first chapter, a smart passive balancing method is proposed, while the other chapters focus on the active inductive balancing methods. Topologies are investigated such as forward, fly-back, two times less windings than cells, Cuk and resonant types. To verify the validity of balancing systems, experimental and simulation results are performed