I. Introduction
High voltage (HV) BMS is widely needed in many applications, e.g., EV and HEV, where many battery modules are assembled and integrated. These modules are composed of many series of batteries to generate a high supply voltage. If the battery module is made of series batteries, they will be unavoidably unbalanced among battery cells in voltage and capacity after a few times of charging and discharging cycles. Notably, the above hazard is always happened no matter when the battery module is charging and discharging. If either over-charge or over-discharge occurs to any battery cell, the efficiency and health of the battery will be degraded. What even worse is that the Li-lon battery might be burned out and exploded. Therefore, BMS with charge equalization is critically required in battery-operated applications.