Double-Tiered Switched-Capacitor Battery Charge Equalization Technique


The automobile industry is progressing toward hybrid, plug-in hybrid, and fully electric vehicles in their future car models. The energy storage unit is one of the most important blocks in the power train of future electric-drive vehicles. Batteries and/or ultracapacitors are the most prominent storage systems utilized so far. Hence, their reliability during the lifetime of the vehicle is of great importance. Charge equalization of series-connected batteries or ultracapacitors is essential due to the capacity imbalances stemming from manufacturing, ensuing driving environment, and operational usage. Double-tiered capacitive charge shuttling technique is introduced and applied to a battery system in order to balance the battery-cell voltages. Parameters in the system are varied, and their effects on the performance of the system are determined. Results are compared to a single-tiered approach. MATLAB simulation shows a substantial improvement in charge transport using the new topology. Experimental results verifying simulation are presented.


Electrical and Computer Engineering


National Science Foundation (U.S.)


This work was supported by the National Science Foundation under Grant 0640636.

Keywords and Phrases

Automobile Industries; Batteries; Battery Systems; Car Models; Cell Voltages; Charge Equalization; Charge Transports; Driving Environments; Electric-Drive Vehicles; Energy Storage Units; Matlab Simulations; Operational Usages; Plug-In; Power Trains; Storage Systems; Switched Capacitors; Ultracapacitors; Automobile Drivers; Electric Automobiles; Engineering Exhibitions; Land Vehicle Propulsion; MATLAB; Model Automobiles; Capacitors

International Standard Serial Number (ISSN)

0278-0046; 1557-9948

Document Type

Article - Journal

Document Version


File Type





© 2008 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Jun 2008