Sorry, you need to enable JavaScript to visit this website.

Dynamic Cell-Level Control for Battery Packs

Utah State University (USU)

Robust Cell-level Modeling and Control of Large Battery Packs

Image of USU's technology
Program: 
ARPA-E Award: 
$3,628,136
Location: 
Logan, UT
Project Term: 
01/01/2013 to 04/06/2017
Project Status: 
ALUMNI
Technical Categories: 
Critical Need: 

Today's electric vehicle batteries are expensive and prone to unexpected failure. Batteries are complex systems, and developing techniques to cost-effectively monitor and manage important performance measures while predicting battery cell degradation and failure remains a key technological challenge. There is a critical need for breakthrough technologies that can be practically deployed for superior management of both electric vehicle batteries and renewable energy storage systems.

Project Innovation + Advantages: 

USU is developing electronic hardware and control software to create an advanced battery management system that actively maximizes the performance of each cell in a battery pack. No two battery cells are alike--they differ over their life-times in terms of charge and discharge rates, capacity, and temperature characteristics, among other things. Traditionally, these issues have been managed by matching similarly performing cells at the factory level and conservative design and operation of battery packs, but this is an incomplete solution, leading to costly batching of cells and overdesign of battery packs. USU's flexible, modular, cost-effective design would represent a dramatic departure from today's systems, offering dynamic control at the cell-level to their physical limits and side stepping existing issues regarding the mismatch and uncertainty of battery cells throughout their useful life.

Potential Impact: 

If successful, USU's dynamic, cell-level control system would substantially reduce electric vehicle battery pack cost by increasing the system-level tolerance to mismatched cells, which could facilitate greater electric, hybrid-electric, and plug-in hybrid-electric vehicle adoption by consumers.

Security: 

Advances in energy storage management could reduce the cost and increase the adoption of electric vehicles and renewable energy storage technologies, which in turn would reduce our nation's dependence on foreign sources of energy.

Environment: 

Improving the reliability and safety of electric vehicles and renewable energy storage facilities would enable more widespread use of these technologies, resulting in a substantial reduction in carbon dioxide emissions.

Economy: 

Enabling alternatives to conventional sources of energy could insulate consumers, businesses, and utilities from unexpected price swings.

Innovation Update: 

(As of December 2016) 

The USU team and its partners have developed an advanced cell-level Battery Management System (BMS) that actively maximizes the performance of each individual cell within a battery pack. The new architecture reduces cell imbalance and increases the pack’s lifetime. Based on industry feedback, the team will next demonstrate a new, cost-constrained power architecture that manages power among small groupings of cells. An internal development program funded by a major automotive manufacturer has launched a demonstration effort, which, if successful, could put the team’s technology on a path for large-scale deployment on a U.S.-manufactured vehicle in the next decade. The team is also exploring other application areas. For example, the Office of Navy Research has contracted the team to apply their BMS technology to an energy storage demonstration on a tactical microgrid, which would enable “plug-and-play” operation of different energy storage assets on the same electrical bus. 

Utilizing a bypass DC-DC converter circuit for each cell in the pack, the circuit topology creates a parallel pathway for current to flow and allows cell-level information to be utilized to optimally deploy each cell’s stored energy. The team developed and incorporated “active life balancing” that biases stronger cells to carry more of the electrical load, thus enabling more of the pack’s capacity to be used over a greater number of cycles. When applied on a 7.5kWh Ford Plug-In Hybrid Electric Vehicle demonstration pack for more than a year of accelerated dynamic cycling, cell imbalance was reduced to half of that presented by the standard passive balancing system and the end-of-life target was exceeded. The team projects to yield a 25% increased pack lifetime.  

For a detailed assessment of the USU project and impact, please click here.

 

Contacts
ARPA-E Program Director: 
Dr. Patrick McGrath
Project Contact: 
Prof. Regan Zane
Partners
Ford Motor Company
National Renewable Energy Laboratory
University of Colorado, Boulder
University of Colorado, Colorado Springs
Release Date: 
8/12/2012