Ahmad Pesaran

Battery thermal models for hybrid vehicle simulations

Abstract This paper summarizes battery thermal modeling capabilities for: (1) an advanced vehicle simulator (ADVISOR); and (2) battery module and pack thermal design. The National Renewable Energy Laboratory’s (NREL’s) ADVISOR is developed in the Matlab/Simulink environment. There are several battery models in ADVISOR for various chemistry types. Each one of these models requires a thermal model to predict the temperature change that could affect battery performance parameters, such as resistance, capacity and state of charges. A lumped capacitance battery thermal model in the Matlab/Simulink environment was developed that included the ADVISOR battery performance models. For thermal evaluation and design of battery modules and packs, NREL has been using various computer aided engineering tools including commercial finite element analysis software. This paper will discuss the thermal ADVISOR battery model and its results, along with the results of finite element modeling that were presented at the workshop on “Development of Advanced Battery Engineering Models” in August 2001.

Comparison of Plug-In Hybrid Electric Vehicle Battery Life Across Geographies and Drive Cycles

In a laboratory environment, it is cost prohibitive to run automotive battery aging experiments across a wide range of possible ambient environment, drive cycle and charging scenarios. Since worst-case scenarios drive the conservative sizing of electric-drive vehicle batteries, it is useful to understand how and why those scenarios arise and what design or control actions might be taken to mitigate them. In an effort to explore this problem, this paper applies a semi-empirical life model of the graphite/nickel-cobalt-aluminum lithium-ion chemistry to investigate impacts of geographic environments under storage and simplified cycling conditions. The model is then applied to analyze complex cycling conditions, using battery charge/discharge profiles generated from simulations of PHEV10 and PHEV40 vehicles across 782 single-day driving cycles taken from Texas travel survey data.

Thermal Evaluation of Toyota Prius Battery Pack

As part of a U.S. Department of Energy supported study, the National Renewable Energy Laboratory has benchmarked a Toyota Prius hybrid electric vehicle from three aspects: system analysis, auxiliary loads, and battery pack thermal performance. This paper focuses on the testing of the battery back out of the vehicle. More recent in-vehicle dynamometer tests have confirmed these out-of-vehicle tests. Our purpose was to understand how the batteries were packaged and performed from a thermal perspective. The Prius NiMH battery pack was tested at various temperatures (0°C, 25°C, and 40°C) and under driving cycles (HWFET, FTP, and US06). The airflow through the pack was also analyzed. Overall, we found that the U.S. Prius battery pack thermal management system incorporates interesting features and performs well under tested conditions.

Thermal characteristics of selected EV and HEV batteries

Battery management is essential for achieving desired performance and life cycle from a particular battery pack in electric and hybrid electric vehicles (EV and HEV). The batteries must be thermally managed in addition to the electrical control. In order to design battery pack management systems, the designers need to know the thermal characteristics of modules and batteries. Thermal characteristics that are needed include heat capacity of modules, temperature distribution and heat generation from modules under various charge/discharge profiles. In the last few years, the authors have been investigating thermal management of batteries and conducting tests to obtain thermal characteristics of various EV and HEV batteries. They used a calorimeter to measure heat capacity and heat generation from batteries and infrared equipment to obtain thermal images of battery modules under load. In this paper, they present their approach for thermal characterization of batteries (heat generation, heat capacity, and thermal images) by providing selected data on valve regulated lead acid, lithium ion, and nickel zinc battery modules/cells. For each battery type, the heat generation rate depends on the initial state of charge, initial temperature, and charge/discharge profile. Thermal imaging indicated that the temperature distribution in modules/cells depends on their design.

A Techno-Economic Analysis of PEV Battery Second Use: Repurposed-Battery Selling Price and Commercial and Industrial End-User Value

Accelerated market penetration of plug-in electric vehicles and deployment of grid-connected energy storage are restricted by the high cost of lithium-ion batteries. Research, development, and manufacturing are underway to lower material costs, enhance process efficiencies, and increase production volumes. A fraction of the battery cost may be recovered after vehicular service by reusing the battery where it may have sufficient performance for other energy-storage applications. By extracting post-vehicle additional services and revenue from the battery, the total lifetime value of the battery is increased. The overall cost of energy-storage solutions for both primary (automotive) and secondary (grid) customer could be decreased. This techno-economic analysis of battery second use considers effects of battery degradation in both automotive and grid service, repurposing costs, balance-of-system costs, the value of aggregated energy-storage to commercial and industrial end users, and competitive technology. Batteries from plug-in electric vehicles can economically be used to serve the power quality and reliability needs of commercial and industrial end users. However, the value to the automotive battery owner is small (e.g.,

A Modular Battery Management System for HEVs

20-

Search for an optimized cyclic charging algorithm for valve-regulated lead–acid batteries

100/kWh) as declining future battery costs and other factors strongly affect salvage value. Repurposed automotive battery prices may range from

Use of unglazed transpired solar collectors for desiccant cooling

38/kWh to

A Second Life for Electric Vehicle Batteries: Answering Questions on Battery Degradation and Value

132/kWh.

Energy Efficient Battery Heating in Cold Climates

Proper electric and thermal management of an HEV battery pack, consisting of many modules of cells, is imperative. During operation, voltage and temperature differences in the modules/cells can lead to electrical imbalances from module to module and decrease pack performance by as much as 25%. An active battery management system (BMS) is a must to monitor, control, and balance the pack. The University of Toledo, with funding from the U.S. Department of Energy and in collaboration with DaimlerChrysler and the National Renewable Energy Laboratory has developed a modular battery management system for HEVs. This modular unit is a 2 nd generation system, as compared to a previous 1 st