Winter 2-1-2010 Battery System Modeling and User Study for Emerging Green-Energy Transportation ; CU-CS-1061-10

Battery technology is the key bottleneck in many cyberphysical systems (CPS). For green-energy CPS transportation applications, such as hybrid electrical vehicles (HEVs) and plug-in HEVs (PHEVs), the battery system design is mostly based on lithium-ion rechargeable electrochemical battery technology, which is bulky, expensive, unreliable, and is the primary roadblock for PHEV adoption and market penetration. For PHEVs, the battery system performance and lifetime reliability are further affected by various user-dependent effects. Battery system modeling and user study are thus essential for battery system design and optimization. This paper presents detailed investigation on battery system modeling and user study for emerging PHEVs. The proposed modeling solution can accurately characterize battery system run-time charge-cycle efficiency, and long-term cycle life. In particular, it models battery system capacity variation and fading due to fabrication and run-time aging effects. An embedded monitoring system is designed and deployed in a number of HEVs and PHEVs, which can monitor users’ driving behavior and battery usage at real time. Using the proposed modeling and monitoring solutions, we conduct user study to investigate battery system run-time usage, characterize user driving behavior, and study the impact of user driving patterns on battery system run-time charge-cycle efficiency, capacity variation and reliability, and life-cycle economy. This work is the first step in battery system design and optimization for emerging green-energy CPS transportation applications.