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Representing GHG Reduction Technologies in the Future Fleet with Full Vehicle Simulation

SAE International Journal of Fuels and Lubricants

US Environmental Protection Agency-Andrew Moskalik, Kevin Bolon, Kevin Newman, Jeff Cherry
  • Journal Article
  • 2018-01-1273
Published 2018-04-03 by SAE International in United States
As part of an ongoing assessment of the potential for reducing greenhouse gas (GHG) emissions of light-duty vehicles, the U.S. Environmental Protection Agency (EPA) has implemented an updated methodology for applying the results of full vehicle simulations to the range of vehicles across the entire fleet. The key elements of the updated methodology explored for this article, responsive to stakeholder input on the EPA’s fleet compliance modeling, include (1) greater transparency in the process used to determine technology effectiveness and (2) a more direct incorporation of full vehicle simulation results.This article begins with a summary of the methodology for representing existing technology implementations in the baseline fleet using EPA’s Advanced Light-duty Powertrain and Hybrid Analysis (ALPHA) full vehicle simulation. To characterize future technologies, a full factorial ALPHA simulation of every conventional technology combination to be considered was conducted. The vehicle simulation results were used to automatically generate response surface equations (RSEs), enabling the use of a quick and easily implemented set of specific equations to estimate fleet-wide emissions in place of running time-consuming full vehicle…
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Modeling and Controls Development of 48 V Mild Hybrid Electric Vehicles

U.S. Environmental Protection Agency-SoDuk Lee, Jeff Cherry, Michael Safoutin, Anthony Neam, Joseph McDonald, Kevin Newman
Published 2018-04-03 by SAE International in United States
The Advanced Light-Duty Powertrain and Hybrid Analysis tool (ALPHA) was created by EPA to evaluate the Greenhouse Gas (GHG) emissions of Light-Duty (LD) vehicles. ALPHA is a physics-based, forward-looking, full vehicle computer simulator capable of analyzing various vehicle types combined with different powertrain technologies. The ALPHA desktop application was developed using MATLAB/Simulink. The ALPHA tool was used to evaluate technology effectiveness and off-cycle technologies such as air-conditioning, electrical load reduction technology and road load reduction technologies of conventional, non-hybrid vehicles for the Midterm Evaluation of the 2017-2025 LD GHG rule by the U.S. Environmental Protection Agency (EPA) Office of Transportation and Air Quality (OTAQ). This paper presents controls development, modeling results, and model validation for simulations of a vehicle with a 48 V Belt Integrated Starter Generator (BISG) mild hybrid electric vehicle and an initial model design for a 48 V inline on-axis P2-configuration mild hybrid electric vehicle. Both configurations were modeled with a MATLAB/Simulink/Stateflow tool, which has been integrated into EPA’s ALPHA vehicle model and was also used to model components within Gamma Technology GT-DRIVE simulations.…
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Modeling and Validation of 48V Mild Hybrid Lithium-Ion Battery Pack

SAE International Journal of Alternative Powertrains

U.S. Environmental Protection Agency-SoDuk Lee, Jeff Cherry, Michael Safoutin, Joseph McDonald, Michael Olechiw
  • Journal Article
  • 2018-01-0433
Published 2018-04-03 by SAE International in United States
As part of the midterm evaluation of the 2022-2025 Light-Duty Vehicle Greenhouse Gas (GHG) Standards, the U.S. Environmental Protection Agency (EPA) developed simulation models for studying the effectiveness of 48V mild hybrid electric vehicle (MHEV) technology for reducing CO2 emissions from light-duty vehicles. Simulation and modeling of this technology requires a suitable model of the battery. This article presents the development and validation of a 48V lithium-ion battery model that will be integrated into EPA’s Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) vehicle simulation model and that can also be used within Gamma Technologies, LLC (Westmont, IL) GT-DRIVE™ vehicle simulations. The battery model is a standard equivalent circuit model with the two-time constant resistance-capacitance (RC) blocks. Resistances and capacitances were calculated using test data from an 8 Ah, 0.4 kWh, 48V (nominal) lithium-ion battery obtained from a Tier 1 automotive supplier, A123 Systems, and developed specifically for 48V mild hybrid vehicle applications. The A123 Systems battery has 14 pouch-type lithium-ion cells arranged in a 14 series and 1 parallel (14S1P) configuration. The RC battery model…
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Modeling and Validation of 12V Lead-Acid Battery for Stop-Start Technology

US EPA-SoDuk Lee, Joseph McDonald
US Environmental Protection Agency-Jeff Cherry, Michael Safoutin
Published 2017-03-28 by SAE International in United States
As part of the Midterm Evaluation of the 2017-2025 Light-duty Vehicle Greenhouse Gas Standards, the U.S. Environmental Protection Agency (EPA) developed simulation models for studying the effectiveness of stop-start technology for reducing CO2 emissions from light-duty vehicles.Stop-start technology is widespread in Europe due to high fuel prices and due to stringent EU CO2 emissions standards beginning in 2012. Stop-start has recently appeared as a standard equipment option on high-volume vehicles like the Chevrolet Malibu, Ford Fusion, Chrysler 200, Jeep Cherokee, and Ram 1500 truck. EPA has included stop-start technology in its assessment of CO2-reducing technologies available for compliance with the standards. Simulation and modeling of this technology requires a suitable model of the battery.The introduction of stop-start has stimulated development of 12-volt battery systems capable of providing the enhanced performance and cycle life durability that it requires. Much of this activity has involved advanced lithium-ion chemistries, variations of lead-acid chemistries, such as absorbed-glass-mat (AGM) designs, and lead-carbon formulations.EPA tested several AGM batteries that are used in OEM start-stop systems. The purpose of this testing was…
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Effect of Current and SOC on Round-Trip Energy Efficiency of a Lithium-Iron Phosphate (LiFePO4) Battery Pack

US Environmental Protection Agency-Michael Safoutin, Jeff Cherry, Joseph McDonald, SoDuk Lee
Published 2015-04-14 by SAE International in United States
While equivalent circuit modeling is an effective way to model the performance of automotive Li-ion batteries, in some applications it is more convenient to refer to round-trip energy efficiency. Energy efficiency of either cells or full packs is seldom documented by manufacturers in enough detail to provide an accurate impression of this metric over a range of operating conditions. The energy efficiency of a full battery pack may also be subject to more variables than would be represented by extrapolating results obtained from a single cell, and can be more demanding to measure in an accurate and consistent manner. Roundtrip energy efficiency of a 22.8-kWh A123 Li-ion (Lithium Iron Phosphate, LiFePO4) battery pack was measured by applying a fixed quantity of charge and discharge current between 0.2C and 2C rates and at SOCs between 10% and 90% at an average temperature of 23°C.
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HIL Development and Validation of Lithium-Ion Battery Packs

US Environmental Protection Agency-SoDuk Lee, Jeff Cherry, Byungho Lee, Joseph McDonald, Michael Safoutin
Published 2014-04-01 by SAE International in United States
A Battery Test Facility (BTF) has been constructed at United States Environmental Protection Agency (EPA) to test various automotive battery packs for HEV, PHEV, and EV vehicles. Battery pack tests were performed in the BTF using a battery cycler, testing controllers, battery pack cooler, and a temperature controlled chamber. For e-machine testing and HEV power pack component testing, a variety of different battery packs are needed to power these devices to simulate in-vehicle conditions. For in-house e-machine testing and development, it is cost prohibitive to purchase a variety of battery packs, and also very time-consuming to interpret the battery management systems, CAN signals, and other interfaces for different vehicle manufacturers. Therefore, there is a need to accurately emulate battery pack voltage, power, current, State of Charge (SOC), etc. for testing e-machines as well as performing real-time HIL (Hardware-In-Loop) vehicle simulations by having the ability to instantly select a cell chemistry along with battery pack configuration such as cell capacity, number of cells in series/parallel, coolant type, etc.This paper presents lithium-ion battery pack HIL development and…
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Maneuver-Based Battery-in-the-Loop Testing - Bringing Reality to Lab

SAE International Journal of Alternative Powertrains

AVL France SAS-Nicolas Pereira
AVL Powertrain Engineering Inc.-Oguz H. Dagci
  • Journal Article
  • 2013-01-0157
Published 2013-04-08 by SAE International in United States
The increasing numbers of hybrid electric and full electric vehicle models currently in the market or in the pipeline of automotive OEMs require creative testing mechanisms to drive down development costs and optimize the efficiency of these vehicles. In this paper, such a testing mechanism that has been successfully implemented at the US Environmental Protection Agency National Vehicle and Fuel Emissions Laboratory (EPA NVFEL) is described. In this testing scheme, the units-under-test consist of a battery pack and its associated battery management system (BMS). The remaining subsystems, components, and environment of the vehicle are virtual and modeled in high fidelity. The complete testing system includes the battery pack, battery management system, battery cycler, battery test automation system, and hardware-in-the-loop (HIL) simulation platform that includes powertrain simulation software, vehicle dynamics simulation software, and various electronic systems for real-time model execution and communication. In the HIL simulation platform, first the roads and maneuvers which the vehicle will follow are defined with related traffic conditions. The intelligent driver in the vehicle dynamics simulation software sends control commands to…
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Development of Advanced Light-Duty Powertrain and Hybrid Analysis Tool

US Environmental Protection Agency-Byungho Lee, SoDuk Lee, Jeff Cherry, Anthony Neam, James Sanchez, Ed Nam
Published 2013-04-08 by SAE International in United States
The Advanced Light-Duty Powertrain and Hybrid Analysis tool was created by Environmental Protection Agency to evaluate the greenhouse gas emissions and fuel efficiency of light-duty vehicles. It is a physics-based, forward-looking, full vehicle computer simulator that is capable of analyzing various vehicle types equipped with different powertrain technologies. The software is built on MATLAB/Simulink. This first version release of the simulation tool models conventional vehicles and is capable of evaluating effects of off-cycle technologies on greenhouse gas emissions, such as air conditioning, electrical load reduction, road load reduction by active aerodynamics, and engine start-stop.This paper introduces the simulation tool by describing its basic model architecture and presenting its underlying physics as well as model formulations. It describes the simulation capability along with its graphical user interface of the tool, designed for off-cycle technology analysis purposes. Model validation results are provided by comparing the simulation outputs with conventional production vehicle test data. The paper concludes with a description of the role this model played in determining the effects of off-cycle technologies on greenhouse gas emissions to…
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Complex Systems Method Applied to Identify Carbon Dioxide Emission Reductions for Light-Duty Vehicles for the 2020-2025 Timeframe

Ricardo Inc.-Anrico F. Casadei, Henry H. Huang, Felipe Brandao, John J. Kasab, Wayne A. Thelen
US Environmental Protection Agency-Matthew Brusstar, Jeff Cherry, Ann Chiu, Benjamin D. Ellies, Joseph McDonald
Published 2012-04-16 by SAE International in United States
The U.S. Environmental Protection Agency, U.S. Department of Transportation's National Highway and Traffic Safety Administration, and the California Air Resources Board have recently released proposed new regulations for greenhouse gas emissions and fuel economy for light-duty vehicles and trucks in model years 2017-2025. These proposed regulations intend to significantly reduce greenhouse gas emissions and increase fleet fuel economy from current levels. At the fleet level, these rules the proposed regulations represent a 50% reduction in greenhouse gas emissions by new vehicles in 2025 compared to current fleet levels. At the same time, global growth, especially in developing economies, should continue to drive demand for crude oil and may lead to further fuel price increases. Both of these trends will therefore require light duty vehicles (LDV) to significantly improve their greenhouse gas emissions over the next 5-15 years to meet regulatory requirements and customer demand. In this paper, technology pathways leading to improved light-duty vehicle fuel consumption are described as well as the complex systems methodology used to assess future technology combinations.The complex systems methodology described…
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Teardown-Based Cost Assessment for Use in Setting Greenhouse Gas Emissions Standards

SAE International Journal of Passenger Cars - Mechanical Systems

EPA-Antonio Fernandez
FEV Inc-Thomas Casciani
  • Journal Article
  • 2012-01-1343
Published 2012-04-16 by SAE International in United States
The U.S. Environmental Protection Agency (EPA) contracted with FEV, Inc. to estimate the per-vehicle cost of employing selected advanced efficiency-improving technologies in light-duty motor vehicles. The development of transparent, reliable cost analyses that are accessible to all interested stakeholders has played a crucial role in establishing feasible and cost effective standards to improve fuel economy and reduce greenhouse gas (GHG) emissions.The FEV team, together with engineering staff from EPA's National Vehicle and Fuel Emissions Laboratory, and FEV's subcontractor, Munro & Associates, developed a robust costing methodology based on tearing down, to the piece part level, relevant systems, sub-systems, and assemblies from vehicles “with and without” the technologies being evaluated. The parts found to be redesigned, added, or deleted to implement the new technologies were then examined by the team's manufacturing experts to assess their material composition and sequence of fabrication steps. Finally, using information from comprehensive costing databases for raw materials, labor rates, manufacturing overhead, and mark-up costs, each technology's direct manufacturing cost was determined. Where appropriate, these results were scaled to other vehicle sizes…
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