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2015-04-14
Technical Paper
2015-01-1191
Jiangong Zhu, Zechang Sun, Xuezhe Wei, Haifeng Dai
Abstract An electrochemical impedance spectroscopy battery model based on the porous electrode theory is used in the paper, which can comprehensively depict the internal state of the battery. The effect of battery key parameters (the radius of particle, electrochemical reaction rate constant, solid/electrolyte diffusion coefficient, conductivity) to the simulated impedance spectroscopy are discussed. Based on the EIS analysis, a lithium-ion battery optimized equivalent circuit model is built. The parameters in the equivalent circuit model have more clear physical meaning. The reliability of the optimized equivalent circuit model is verified by compared the model and experiments. The relationship between the external condition and internal resistance could be studied according to the optimized equivalent circuit model. Thus the internal process of the power battery is better understood.
2015-04-14
Technical Paper
2015-01-1196
Jeremy S. Neubauer, Eric Wood
Abstract Fast charging is attractive to battery electric vehicle (BEV) drivers for its ability to enable long-distance travel and to quickly recharge depleted batteries on short notice. However, such aggressive charging and the sustained vehicle operation that results could lead to excessive battery temperatures and degradation. Properly assessing the consequences of fast charging requires accounting for disparate cycling, heating, and aging of individual cells in large BEV packs when subjected to realistic travel patterns, usage of fast chargers, and climates over long durations (i.e., years). The U.S. Department of Energy's Vehicle Technologies Office has supported the National Renewable Energy Laboratory's development of BLAST-V-the Battery Lifetime Analysis and Simulation Tool for Vehicles-to create a tool capable of accounting for all of these factors. We present on the findings of applying this tool to realistic fast charge scenarios.
2015-04-14
Technical Paper
2015-01-1195
Kiyotaka Maeda, Masashi Takahashi
Abstract To verify the appropriateness of the vibration test conditions of ISO 12405, we performed tailoring to derive power spectrum densities and test durations as vibration test conditions. Vehicles used for tailoring included two electric vehicles and one plug-in hybrid electric vehicle. Those vehicles were equipped with accelerometers and were run on seven different road types at different speeds while data on the acceleration of the battery packs were recorded. The power spectrum densities for three axes that were derived from the obtained acceleration data were similar in form to the power spectrum densities of ISO 12405, and almost the same root mean square accelerations were obtained, confirming that they are appropriate. However, both experiments and theory suggest that the test duration for the Z-axis exceeds those of the X- and Y-axes.
2015-04-14
Technical Paper
2015-01-1183
Padmanaban Dheenadhayalan, Anush Nair, Mithun Manalikandy, Anurag Reghu, Jacob John, V S Rani
Abstract Hybrid and electric vehicles are becoming increasingly popular these days owing to concerns over exhaustion of conventional fuel sources, pollution from combustion, as well as high carbon foot print of these fuels. Lithium-ion batteries are widely preferred as the source of power for hybrid and electric vehicles because of their high monomer voltage and high energy density. Accurate estimation of the State of Charge (SoC) of battery is crucial in the electric vehicle. It provides the information on the range of operation of the vehicle. It also ensures the safety and reliability of the battery unit. Accurate State of Charge estimation also enables more optimized battery pack design for the electric vehicle. Conventional methods for State of Charge estimation such as Coulomb counting and Open Circuit Voltage (OCV) measurement suffer from inaccuracies and is affected by noise during the vehicle operation.
2015-04-14
Technical Paper
2015-01-1181
Zhihong Jin, Zhenli Zhang, Timur Aliyev, Anthony Rick, Brian Sisk
Abstract Power limit estimation of a lithium-ion battery pack can be employed by a battery management system (BMS) to balance a variety of operational considerations, including optimization of pulse capability while avoiding damage and minimizing aging. Consideration of cell-to-cell performance variability of lithium-ion batteries is critical to correct estimation of the battery pack power limit as well as proper sizing of the individual cells in the battery. Further, understanding of cell variability is necessary to protect the cell and other system components (e.g., fuse and contactor, from over-current damage). In this work, we present the use of an equivalent circuit model for estimation of the power limit of lithium-ion battery packs by considering the individual cell variability under current or voltage constraints. We compare the power limit estimation by using individual cell characteristics compared to the estimate found using only max/min values of cell characteristics.
2015-04-14
Technical Paper
2015-01-1182
Mehrdad Mastali Majdabadi Kohneh, Ehsan Samadani, Siamak Farhad, Roydon Fraser, Michael Fowler
Abstract Lithium-ion batteries (LIBs) are one of the best candidates as energy storage systems for automobile applications due to their high power and energy densities. However, durability in comparison to other battery chemistries continues to be key factor in prevention of wide scale adoption by the automotive industry. In order to design more-durable, longer-life, batteries, reliable and predictive battery models are required. In this paper, an effective model for simulating full-size LIBs is employed that can predict the operating voltage of the cell and the distribution of variables such as electrochemical current generation and battery state of charge (SOC). This predictive ability is used to examine the effect of parameters such as current collector thickness and tab location for the purpose of reducing non-uniform voltage and current distribution in the cell. It is identified that reducing the non-uniformities can reduce the ageing effects and increase the battery durability.
2015-04-14
Technical Paper
2015-01-1188
Seongjun Yun, SungJin Park, Daekwang Kim, Junyong Lee, Sejun Kim, Kwang-yeon Kim
Abstract The fuel economy of a vehicle can be improved by recuperating the kinetic energy when the vehicle is decelerated. However, if there is no electrical traction component, the recuperated energy can be used only by the other electrical systems of the vehicle. Thus, the fuel economy improvement can be maximized by balancing the recuperated energy and the consumed energy. Also, suitable alternator and battery management is required to maximize the fuel economy. This paper describes a design optimization process of the alternator and battery system equipped with recuperation control algorithms for a mid-sized sedan based on the fuel economy and system cost. A vehicle model using AVL Cruise is developed for cycle simulations and validated with experimental data. The validated model is used for the parametric study and design optimization of the alternator and battery systems with single and dual energy storage.
2015-04-14
Technical Paper
2015-01-1185
Brian Sisk, Timur Aliyev, Zhenli Zhang, Zhihong Jin, Negin Salami, Kem Obasih, Anthony Rick
Abstract Competitive engineering of battery packs for vehicle applications requires a careful alignment of function against vehicle manufacturer requirements. Traditional battery engineering practices focus on flow down of requirements from the top-level system requirements through to low-level components, meeting or exceeding each requirement at every level. This process can easily produce an over-engineered, cost-uncompetitive product. By integrating the key limiting factors of battery performance, we can directly compare battery capability to requirements. Here, we consider a power-oriented microhybrid battery system using coupled thermal and electrochemical modeling. We demonstrate that using dynamic resistance acquired from drive cycle characteristics can reduce the total size of the pack compared to typical static, fixed-duration resistance values.
2015-04-14
Technical Paper
2015-01-1186
Michael Safoutin, Jeff Cherry, Joseph McDonald, SoDuk Lee
Abstract 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.
2015-04-14
Technical Paper
2015-01-1180
Letao Zhu, Zechang Sun, Haifeng Dai, Xuezhe Wei
Abstract This paper aims at accurately modeling the nonlinear hysteretic relationship between open circuit voltage (OCV) and state of charge (SOC) for LiFePO4 batteries. The OCV-SOC hysteresis model is based on the discrete Preisach approach which divides the Preisach triangle into finite squares. To determine the weight of each square, a linear function system is constructed including a series of linear equations formulated at every sample time. This function system can be solved by computer offline. When applying this approach online, the calculated square weight vector is pre-stored in advance. Then through multiple operations with hysteresis state vector of squares updated online at every sampling time, the SOC considering the influence of OCV-SOC hysteresis is predicted.
2015-04-14
Technical Paper
2015-01-1179
Christopher J. Brooks, Eric Kreidler
Abstract Significant research has been underway for many years to develop technologies to electrochemically power vehicles with limited success. Unfortunately, most technologies fail to achieve theoretical performance and/or are prohibitively too expensive for mass marketed vehicles. Most of the issues with electrochemical technologies can ultimately be attributed to materials issues, whether it is cost, durability, or activity. A broad examination of potential electrochemical technologies is provided identifying key materials issues with each. Included are the results of recent research involving lithium-oxygen batteries. The observations from this research have identified the electrochemical product, lithium peroxide, and its properties to be the most pressing material issue for lithium-oxygen battery. A future research vision is proposed counter to the current research trend of electrocatalyst/electrolyte development.
2015-04-14
Technical Paper
2015-01-1154
Benjamin Black, Tomohiro Morita, Yusuke Minami, David Farnia
Abstract Test and validation of control systems for hybrid vehicle power trains provide a unique set of challenges. Not only does the electronic control unit (ECU), or pair of ECUs, need to smoothly coordinate power flow between two or more power plants, but it also must handle the power electronics' high-speed dynamics due to PWM signals frequently in the 10-20 kHz range. The trend in testing all-electric and hybrid-electric ECUs has moved toward using field-programmable gate arrays (FPGAs) as the processing node for simulating inverter and electric motor dynamics in real time. Acting as a purpose-built processor colocated with analog and digital input and output, the FPGA makes it possible for real-time simulation loop rates on the order of one microsecond.
2015-04-14
Journal Article
2015-01-1306
Jeremy S. Neubauer, Eric Wood, Ahmad Pesaran
Abstract Battery second use-putting used plug-in electric vehicle (PEV) batteries into secondary service following their automotive tenure-has been proposed as a means to decrease the cost of PEVs while providing low cost energy storage to other fields (e.g., electric utility markets). To understand the value of used automotive batteries, however, we must first answer several key questions related to battery degradation, including: How long will PEV batteries last in automotive service? How healthy will PEV batteries be when they leave automotive service? How long will retired PEV batteries last in second-use service? How well can we best predict the second-use lifetime of a used automotive battery? Under the support of the U.S. Department of Energy's Vehicle Technologies Office, the National Renewable Energy Laboratory has developed a methodology and the requisite tools to answer these questions, including the Battery Lifetime Simulation Tool (BLAST).
2015-04-14
Technical Paper
2015-01-0493
Ying Wang, Ye Wang, You Qu, Sumin Zhang, Weiwen Deng
Abstract Vision-based Advanced Driver Assistance Systems has achieved rapid growth in recent years. Since vehicle field testing under various driving scenarios can be costly, tedious, unrepeatable, and often dangerous, simulation has thus become an effective means that reduces or partially replaces the conventional field testing in the early development stage. However, most of the commercial tools are lack of elaborate lens/sensor models for the vehicle mounted cameras. This paper presents the system-based camera modeling method integrated virtual environment for vision-based ADAS design, development and testing. We present how to simulate two types of cameras with virtual 3D models and graphic render: Pinhole camera and Fisheye camera. We also give out an application named Envelope based on pinhole camera model which refers to the coverage of Field-of-Views (FOVs) of one or more cameras projected to a specific plane.
2015-04-14
Technical Paper
2015-01-0575
SongAn Zhang, Qing Zhou, Yong Xia
Abstract Small lightweight electric vehicle (SLEV) is an approach for compensating low energy density of the current battery. However, small lightweight vehicle presents technical challenges to crash safety design. One issue is that mass of battery pack and occupants is a significant portion of vehicle's total weight, and therefore, the mass distribution has great influence on crash response. This paper presents a parametric analysis using finite element modeling. We first build LS-DYNA model of a two-seater SLEV with curb weight of 600 kg. The model has no complex components and can provide reasonable crash pulses under full frontal rigid barrier crash loading and offset deformable barrier (ODB) crash loading.
2015-04-14
Technical Paper
2015-01-0618
Zhihong Dong, Ying Sun, Guitao Zhu, Shihu Wang, Jian Zeng, Yuliang Yang
Abstract Based on the modal frequency response theory and experiment, the installation layout evaluation and structural optimization method for SIS(side impact sensors) installation position is studied. Establish the finite element model including B-pillar, roof and floor with local constraint. Than study the key parameter's influence on the frequency response analysis results, and the simulation results are correlated by experiment. In view of the installation layout requirements of side impact sensors, the structure optimization method for installation position of side impact sensor is put forward. The optimal scheme is confirmed by the finite element analysis, and a final experimental verification was implemented by a real vehicle test.
2015-04-14
Technical Paper
2015-01-1382
Lisa Schei Blikeng, Siril Hegén Agerup
Abstract This paper is based on the bachelor thesis “Fire in electric cars” [1] 2013, written in Norwegian. The number of electric vehicles has increased significantly in recent years. Today, there are more than 35,000 electric cars in Norway, and the government's goal is 200,000 cars by 2020. [3] The main question investigated was: What happens when the lithium-ion battery pack ignites? The major part of this assignment was to perform a full-scale fire experiment with a modern and drivable electric car. This experiment took place in February 2013, when a Peugeot iOn 2012 model was set on fire. The car burned out without any attempt being made to extinguish the fire. We had to supply much heat from the external heat source to achieve thermal runaway in the cells. Observations and results from the experiment indicated that fire in the lithium-ion battery cells consists of two phases.
2015-04-14
Journal Article
2015-01-1379
Hideki Matsumura, Shinichiro Itoh, Kenichi Ando
Abstract Lithium-ion cells are being used in an increasing number of electric and hybrid vehicles. Both of these vehicle types contain many cells. Despite various safety measures, however, there are still reports of accidents involving abnormal heat, smoke, and fire caused by thermal runaway in the cells. If thermal runaway in one cell triggers that of another and thus causes thermal runaway propagation, this can lead to rupture of the battery pack, car fire, or other serious accidents. This study is aimed to ensure the safety of vehicles with lithium-ion cells by clarifying such accident risks, and so we investigated the process of thermal runaway propagation. In the experiment, we created a battery module made of seven laminate-type cells tightly stacked one on another. Then, we induced thermal runaway in one of the cells, measured the surface temperatures of the cells, and collected video data as the process developed. As a result, all of the seven cells underwent thermal runaway.
2015-04-14
Technical Paper
2015-01-1375
James Price
Abstract Compressed development cycles drive increased focus on virtual development, including both functional verification and quantitative simulation of electrical system designs. However, one hurdle often cited is the effort needed to develop behavioral models of electrical components such as wires, fuses, and ECUs and time required to run simulation. This presentation shows that it is fully possible to obtain reliable and “good enough” results to aid product development using simpler models and rule based verifications. By placing these models in a re-usable library and providing a simple, visual interaction environment, early design debugging using a computer becomes possible for every electrical engineer.
2015-04-14
Technical Paper
2015-01-1223
Masood Shahverdi, Michael S. Mazzola
Abstract An approach is being pursued for a series hybrid electric vehicle (SHEV). The twin goals of maximizing Fuel Economy (FE) and improving consumer acceptance has led to a SHEV powertrain using energy storage as a means for filtering drive cycle power demands on the engine, rather than an energy source for supplying all-electric mode. The concept is intended to minimize, if not eliminate, the battery in the SHEV without resorting to full range proportional control of the engine and generator. An initial optimization study reported for a mid-size SHEV showed a 4.5 kWh Li-ion battery pack was still required. In a new research, a sports car class SHEV was studied, which inspires this manuscript. The challenge with this vehicle is to reduce the ESS size even more because the available space allocation is only one fourth of the battery size in the mid-size. In this manuscript, a controller is developed that allows a hybridized SHEV to be realized with a light ESS.
2015-04-14
Technical Paper
2015-01-1224
Ipek Sarac, Andreas Wagner, Uta Fischer, Rainer Schnurr
Abstract As the percentage of Hybrid Electric Vehicles (HEV) is increasing, On-Board Diagnosis (OBD) faces new challenges such as limited combustion engine runtime. Moreover, predictive driving strategies for HEV assure that more vehicles are equipped with navigation systems. These systems can provide information about the road conditions such as limit speed, curvature and slope. In this study, navigation road information is used to predict monitoring conditions of OBD functions so that the available OBD time can be used effectively. As an example, catalyst monitoring is considered and a simple vehicle model is proposed which takes velocity and slope prediction from the navigation system to predict torque and exhaust mass flow. The model is composed of a combination of longitudinal motion and a power train torque transition model. Results of this effort are presented for different velocity profiles.
2015-04-14
Technical Paper
2015-01-1226
Michael Bassett, Bruno Brods, Jonathan Hall, Stephen Borman, Matthew Grove, Simon Reader
Abstract In 2012 MAHLE Powertrain developed a range-extended electric vehicle (REEV) demonstrator, based on a series hybrid configuration, and uses a battery to store electrical energy from the grid. Once the battery state of charge (SOC) is depleted a gasoline engine (range extender) is activated to provide the energy required to propel the vehicle. As part of the continuing development of this vehicle, MAHLE Powertrain has developed control software which can intelligently manage the use of the battery energy through the combined use of GPS and road topographical data. Advanced knowledge of the route prior to the start of a journey enables the software to calculate the SOC throughout the journey and pre-determine the optimum operating strategy for the range extender to enable best charging efficiency and minimize NVH. The software can also operate without a pre-determined route being selected.
2015-04-14
Technical Paper
2015-01-1230
Ahmed Imtiaz Uddin, Jerry Ku
Abstract It is well known that thermal management is a key factor in design and performance analysis of Lithium-ion (Li-ion) battery, which is widely adopted for hybrid and electric vehicles. In this paper, an air cooled battery thermal management system design has been proposed and analyzed for mild hybrid vehicle application. Computational Fluid Dynamics (CFD) analysis was performed using CD-adapco's STAR-CCM+ solver and Battery Simulation Module (BMS) application to predict the temperature distribution within a module comprised of twelve 40Ah Superior Lithium Polymer Battery (SLPB) cells connected in series. The cells are cooled by air through aluminum cooling plate sandwiched in-between every pair of cells. The cooling plate has extended the cooling surface area exposed to cooling air flow. Cell level electrical and thermal simulation results were validated against experimental measurements.
2015-04-14
Technical Paper
2015-01-1217
Changhong Liu, Lin Liu
Abstract Many problems are associated with the large battery operation current, such as battery overheating, lithium plating, and mechanical structural instability of battery materials. All these problems may cause battery safety issues in fuel cell hybrid vehicles (FCHVs), e.g., battery explosions and thermal runaway have been reported and may cause public anxiety about FCHVs. Previous researches on FCHV power management strategy have focused on minimizing fuel consumption. But more attention needs to put on the battery current constraint for analysis of battery state of charge (SOC) and battery state of health (SOH). This research targets optimizing the FCHV battery pack operation within a safe current range through power management strategy to increase the safety of the battery pack while improving battery usage via SOC control. Battery SOH is also evaluated in the study.
2015-04-14
Technical Paper
2015-01-1390
Venk Kandadai, Helen Loeb, Guyrandy Jean-Gilles, Catherine McDonald, Andrew Winston, Thomas Seacrist, Flaura Winston
Abstract Driving simulators offer a safe alternative to on-road driving for the evaluation of driving performance. Standardized procedures for providing individualized feedback on driving performance are not readily available. The aim of this paper is to describe a methodology for developing standardized procedures that provide individualized feedback (“LiveMetrics”) from a simulated driving assessment used to measure driving performance. A preliminary evaluation is presented to test the performance of the LiveMetrics methodology. Three key performance indicators are used to evaluate the performance and utility of the method in the context of the preliminary evaluation. The results from the preliminary evaluation suggest abilities to customize reporting features for feedback and integrate these into existing driver training and education programs.
2015-04-14
Technical Paper
2015-01-1399
Dee Kivett, Victor Gallas Cervo, Aparna Mantha, John Smith
Abstract A common result of aging is a decline in peripheral vision. This study provides a preliminary feasibility analysis of an improved method for alerting drivers of oncoming traffic in blind-spots. Luminescence with an intuitive color-scheme is used as the primary stimulus to permeate a wider field of useful vision than that of existing technology in use today. This method was developed based on concepts of affordance-based design through its adaptation to address specific cognitive and visual acuity challenges of the elderly. The result is an improved, intuitive technique for hazard alert that shows significant improvement over existing technology for all age groups, not just the elderly.
2015-04-14
Technical Paper
2015-01-1401
Pawel Skruch, Rafal Dlugosz, Krzysztof Kogut, Pawel Markiewicz, Dominik Sasin, Maciej Różewicz
Abstract Active Safety (AS) and Advanced Driver Assistance Systems (ADAS) can nowadays be considered as distributed embedded software systems where independent microprocessor systems communicate together using different communication protocols. Typical AS or ADAS functionality is then realized by several microprocessors communicating with each other. AS and ADAS systems interact with other Electronic Control Units in a vehicle via communication networks and gather vehicle's surroundings via camera, radar or laser sensors. Quality assurance and safety standards combined with increasing complexity and reliability demands related to vision sensing, radar sensing and data fusion, often together with a short time to market, make the development of such systems challenging.
2015-04-14
Technical Paper
2015-01-1211
Zhuoping Yu, Caitao Jian, Songyun Xu, Lu Xiong
Abstract To research the dynamic response of active power source of electronic hydraulic brake system, the paper proposes a restricted distribution control strategy. Building control strategy model and active power source model to simulation with Matlab/Simulink and AMEsim, and bench test is conducted on different driving cycles, which proves that the dynamic response of active power source is fit and controllable by adjusting PID parameters.
2015-04-14
Journal Article
2015-01-1400
Umashankar Nagarajan, Ambarish Goswami
Abstract The number of seniors is rising worldwide. Exoskeleton devices can help seniors regain their lost power, balance, and agility, thus improving their quality of life. Exoskeleton devices and control strategies assist human gait. A common strategy is to use oscillator-based controllers, which “lock in” with the gait and help the subject walk faster using a phase lead characteristic. Such strategies are limited to gait assist only and are less effective in more general movements. These controllers can be detrimental in critical cases such as when the leg needs to execute a fast reactive stepping to stop a fall. We present a control strategy for a hip exoskeleton, which assists human leg motion by providing motion amplification at the hip joint. The controller is “neutral” because it assists any leg motion, not only a gait, and can help avoid falls by assisting reactive stepping.
2015-04-14
Journal Article
2015-01-1403
Yi lu Murphey, Dev S. Kochhar, Paul Watta, Xipeng Wang, Tianyu Wang
Abstract Side swipe accidents occur primarily when drivers attempt an improper lane change, drift out of lane, or the vehicle loses lateral traction. Past studies of lane change detection have relied on vehicular data, such as steering angle, velocity, and acceleration. In this paper, we use three physiological signals from the driver to detect lane changes before the event actually occurs. These are the electrocardiogram (ECG), galvanic skin response (GSR), and respiration rate (RR) and were determined, in prior studies, to best reflect a driver's response to the driving environment. A novel system is proposed which uses a Granger causality test for feature selection and a neural network for classification. Test results showed that for 30 lane change events and 60 non lane change events in on-the-road driving, a true positive rate of 70% and a false positive rate of 10% was obtained.
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