Passive balancing in battery management system for electrical vehicles

Due to the peak energy and power density, the battery is a leading energy source for electric vehicles. Among various battery chemistries, Li-ion batteries have emerged as serious competitors in the field of electric vehicles. The battery cells are connected in series or parallel to increase voltage and current in a battery pack for electric vehicle applications. The heart of a battery-operated electric vehicle is the battery control system. The series-connected cells in a battery pack must preserve each cell's original potential under ideal charging and discharging conditions. If the potential of connected cells is not balanced, the charging and discharging of cells in the pack will be affected, bringing up the issue of cells that are out of balance due to inherent and extrinsic factors. Using active and passive cell balancing techniques can solve this issue. The right cell balancing technique can shorten the battery pack's equalization time and enhance its ageing. This paper explains the parameters of a battery, the function of the BMS, and different cell balancing techniques for use in electric vehicle applications.