Comparative study of cell balancing techniques for battery module performance optimization

Imbalance can be caused by anything that can make one's cells so different from others and the reason behind this imbalance are different coulomb efficiency, self-discharge rates, thermal runaway, cell degradation, and incomplete charging of cell pack. These problems may affect overall performance of the pack and hindrance to safety. This paper includes information related to different cell balancing techniques which are further classified into two categories passive and active based on the elements used. The passive technique makes use of a resistor to dissipate extra energy in the form of heat loss while the active one uses inductors, capacitors, and power electronic converters to transfer energy among cells. A comparison is also made on active vs passive in the form of a table as a result it comes to know active cell balancing has an upper edge in various aspects such as fast operating speed, higher efficiency, less balancing time, high safety level, and better performance even though it also has one disadvantage of a complex algorithm, high cost and we cannot transfer energy from lower cell to higher charged cell. As per the applications point of view, this is clear now passive technique can only be used in lower power applications and in portable tools while on the other hand active can be used in higher power applications such as electric vehicles with the battery management system (BMS). This paper includes a theoretical review of various topologies of cell balancing including their advantages and disadvantages which will guide us to select the proper technique or method as per our requirements for energy storage applications.