Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


akron1190318540.pdf (3.32 MB)

ETD Abstract Container

Abstract Header

A FAILURE ACCOMMODATING BATTERY MANAGEMENT SYSTEM WITH INDIVIDUAL CELL EQUALIZERS AND STATE OF CHARGE OBSERVERS

Annavajjula, Vamsi Krishna
http://rave.ohiolink.edu/etdc/view?acc_num=akron1190318540

Abstract Details

2007, Master of Science, University of Akron, Electrical Engineering.
Lithium-ion batteries are the most commonly chosen power source for many portable applications. Advantages like high energy density, high nominal voltage, less maintenance, and low self discharge rate are the driving force behind this choice. Although they have many advantages, lithium-ion batteries have not been used in various applications because of the difficulty of using them well and keeping the individual cells balanced in a series-connected battery pack. This provides our motivation to develop a Battery Management System (BMS) with individual cell equalizers and state of charge (SOC) observers. The main purpose of a BMS is to monitor the cells in a battery pack to ensure proper operation and balance the voltage and charge in the cells in a battery pack in order to maximize the available energy. A BMS was developed for a lithium-ion battery pack with six cells connected in series. The BMS monitors individual cell parameters like voltage, temperature, and current to ensure proper operating conditions and logs this information in an external memory for further processing. Battery model equations are derived, which serve as an SOC observer, to predict and correct the charge stored in the cell. A novel dissipative equalization scheme was proposed to achieve cell equalization among the series-connected cells in terms of both voltage and charge. In contrast to the already published equalization schemes, the proposed scheme achieves equalization among cells in the battery pack in terms of both voltage and stored charge during charging and discharge. Also the proposed battery management system was implemented in hardware to demonstrate its operation. In the event that a cell in the series-connected battery pack fails, the proposed BMS with minor modifications can isolate the failed cell from the battery pack without disturbing the rest of the operation of the pack; this makes the proposed system failure accommodating. Experiments conducted using the implemented BMS show that a charging strategy that includes cell equalization in terms of voltage allows 31% more energy to be stored in the pack than does a simpler strategy that stops charging once the strongest cell in the battery pack reaches the maximum allowable cell voltage. A charging strategy that includes cell equalization in terms of both voltage and stored charge allows 39.33% more energy. The proposed cell equalization scheme during discharge results in an extraction of 82.87% more energy from the battery pack than does a simpler strategy that stops discharging once the weakest cell in the battery pack reaches the minimum allowable voltage.
Joan Carletta (Advisor)
168 p.
Cell Equalization; Battery Management System; Lithium-ion cells; Lithium-ion batteries

Recommended Citations

Citations

  • Annavajjula, V. K. (2007). A FAILURE ACCOMMODATING BATTERY MANAGEMENT SYSTEM WITH INDIVIDUAL CELL EQUALIZERS AND STATE OF CHARGE OBSERVERS [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1190318540

    APA Style (7th edition)

  • Annavajjula, Vamsi. A FAILURE ACCOMMODATING BATTERY MANAGEMENT SYSTEM WITH INDIVIDUAL CELL EQUALIZERS AND STATE OF CHARGE OBSERVERS. 2007. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1190318540.

    MLA Style (8th edition)

  • Annavajjula, Vamsi. "A FAILURE ACCOMMODATING BATTERY MANAGEMENT SYSTEM WITH INDIVIDUAL CELL EQUALIZERS AND STATE OF CHARGE OBSERVERS." Master's thesis, University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1190318540

    Chicago Manual of Style (17th edition)

akron1190318540
6,704
© 2007, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.