SBIR Phase I: Platform for Impedance Diagnostics and Power Management for Electric Vehicle Battery Systems

The broader impact/commercial potential of this project centers on furthering scientific understanding of degradation in electrochemical energy storage. The project will explore technology that will enable the large-scale transfer of a key laboratory-proven diagnostic tool from the lab to the field. This tool, called electrochemical impedance spectroscopy (EIS), is a noninvasive assessment of the internal state of a battery. In contrast to current interest-group-initiated, crowd-sourced qualitative research efforts, EIS would enable the collection and analysis of an unprecedented amount of real-time quantitative data to further scientific understanding of electrochemical lifetime and degradation factors of in applications ranging from electric vehicles to grid and building storage. Highly publicized battery pack failures have increased skepticism of electrochemical energy storage in the public eye, and large-scale scientific studies could aid in faster technological improvements to increase widespread adoption of electrochemical energy storage as the U.S. seeks to improve energy independence, efficiency, and security. This Small Business Innovation Research (SBIR) Phase I project addresses the need to innovate on current battery management methods that force battery system overdesign and power/energy underutilization by introducing a platform to enable diagnosis and correction of inherent cell-to-cell imbalances in electric vehicles to improve battery pack performance, reliability, and safety. Specifically, this work deploys electrochemical impedance spectroscopy in a distributed power electronics platform to provide a new toolset for real-time diagnostics and the improved extraction of important information to aid in the determination of battery cell state of charge and state of health. The goal of Phase I Research is to demonstrate efficient and cost-effective scalability of this power-electronics-based EIS. A proof-of-concept prototype has been verified on small-capacity cells, but a commercial solution will need to manage large-capacity cells with much lower impedance which presents control system and EIS accuracy technical challenges. A power converter and accompanying control system will first be developed to meet target specifications, followed by a demonstration board to demonstrate EIS and power management for a number of series-connected cells.