Lithium-Ion Cell Balancing Using Auxiliary Battery and DC/DC Unidirectional Converter

The lithium-ion battery became commercially popular and used due to its salient characteristics such as high terminal voltage, energy density and power density of a single cell. However, if there is no proper power regulation during the process of both charging and discharging. In that case, the life span of the batteries will significantly decrease and leads to undesirable results such as fire or explosion at times. Proper power regulation is essentials, and battery management systems (BMS) are employed to circumvent these problems. SOC estimation, cell balancing, and thermal management are the common subsystems of the battery management system (BMS). This paper focuses on the cell balancing subsystem, where it is a crucial subsystem of the BMS that will efficiently prolong the battery life span. The active balancing topology used in this paper is a Single Switch Capacitor to performed module balancing and cell balancing within internal modules. The BMS is based on the pack modularization architecture, where a single capacitor is being installed for module-tomodule balancing. As for internal module balancing, cells are balanced using a single capacitor with applications of Auxiliary Battery and DC/DC Unidirectional Converter for boost charging purposes. Finally, the simulation of the BMS is being modelled with MATLAB Simulink to validate the results of the implementation system.