Model Based Design of Balancing Systems for Electric Vehicle Battery Packs

Abstract

Original citation:Bruen, Thomas, Marco, James and Gama, Miguel (2015) Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement: A note on versions:The version presented in WRAP is the published version or, version of record, and may be cited as it appears here. Abstract: Battery packs containing multiple cells in series require a balancing system in order to ensure energy and power requirements for the battery pack are maintained throughout its life. Based on the equivalent circuit model (ECM) of a cell, a new framework is proposed which can accommodate a controloriented model of a balancing system while maintaining the same measured input and output as an ECM. This allows for model-based design of the balancing control system and other battery management system functions such as state estimation. Three examples of balancing system models are presented to show how balancing systems can be designed and analyzed. A model-based controller is then designed for one balancing system to show how the framework can be used to generate less heat while removing imbalance at the same rate.

A comprehensive review on inconsistency and equalization technology of lithium‐ion battery for electric vehicles

“…This approach provides a basis for the trade‐off between efficiency and speed when choosing the appropriate balance topology. Bruen et al 79 studied passive equalization mode, C2C mode, and C2M mode respectively and simulated the dynamics current and voltage caused by balancing. The model is versatile and can be used for the auxiliary design of the equalization control system.…”

Review of Battery Cell Balancing Methodologies for Optimizing Battery Pack Performance in Electric Vehicles

“…In this method, the cells with excess energy are discharged through dissipative bypass route as heat until the charge matches those of the lower cells in the pack or charge reference [21], [40], [43], [63] and this will impact the battery run time. The dissipative nature of passive balancing means that there is no distribution of energy between cells since cell energy is wasted as heat [64], a task accomplished by the use of resistors. Therefore, the charge is lost or discharged through a resistor to the air rendering this method to be less efficient and generates a lot of heat.…”

“…Cell imbalance in battery systems is an important matter in the system life of the battery because, without the balancing system, the individual cell voltages will drift apart over time [64], [42], [104], [105], which will result to low efficiency and even hazards. There are various benefits of cell balancing namely:…”

Analysis of a Battery Management System (BMS) Control Strategy for Vibration Aged Nickel Manganese Cobalt Oxide (NMC) Lithium-Ion 18650 Battery Cells

“…However, As discussed in [37] there is no guarantee that the cells will remain similar over their life, and a single effective cell will not account for variations in current and SOC which can occur. Individual ECMs can also be used to implement model-based balancing strategies for cells in series [38].…”