An Enhanced Active Balancing Circuit with Reconfigurable Battery for Electric Vehicles

Abstract

Batteries play a vital role in Electrical Vehicles (EV). In a battery pack, voltage differences always exist due to charging and discharging cycles. It leads to an imbalance in the State of Charge (SoC) of Li-Ion battery packs. State of charge is the level of charge of an electric battery relative to its capacity. The voltage imbalances lead to the degradation of the cells by reducing their life span and usage time. Thus, a balancing circuit is necessary to maintain the same voltage level in all the cells. Also, a reconfiguration of the battery cells depending on their SoC levels and the requirement of the load can increase the usage time and life span of a battery pack. In this paper, a circuit for reconfiguration and active equalization is proposed based on a coupled inductor and switch network which can dynamically transfer charge from the cells with higher voltage to the ones with lower voltage while simultaneously delivering the load. Thus, the SoC of the cells can be balanced with an advantage of the coupled inductor ensuring faster equalization time than other balancing techniques.