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Viewing 61 to 90 of 21633
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
Journal Article
2015-01-1187
Nils Lohmann, Peter Haussmann, Patrick Wesskamp, Joachim Melbert, Thomas Musch
Abstract Battery aging is a main concern within hybrid and electrical cars. Determining the current state-of-health (SOH) of the battery on board of a vehicle is still a challenging task. Electrochemical Impedance Spectroscopy (EIS) is an established laboratory method for the characterization of electrochemical energy storages such as Lithium-Ion (Li-Ion) cells. EIS provides a lot of information about electrochemical processes and their change due to aging. Therefore it can be used to estimate the current SOH of a cell. Standard EIS methods require the excitation of the cell with a certain waveform for obtaining the impedance spectrum. This waveform can be a series of monofrequent sinusoidal signals or a time-domain current pulse with a dedicated Fourier spectrum. However, any form of dedicated perturbation is not generally applicable on board of an electric vehicle.
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
2015-01-1188
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
2015-01-1182
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
2015-01-1183
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
Journal Article
2015-01-1184
Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
Abstract The performance, life cycle cost, and safety of electric and hybrid electric vehicles (EVs and HEVs) depend strongly on their energy storage system. Advanced batteries such as lithium-ion (Li-ion) polymer batteries are quite viable options for storing energy in EVs and HEVs. In addition, thermal management is essential for achieving the desired performance and life cycle from a particular battery. Therefore, to design a thermal management system, a designer must study the thermal characteristics of batteries. The thermal characteristics that are needed include the surface temperature distribution, heat flux, and the heat generation from batteries under various charge/discharge profiles. Therefore, in the first part of the research, surface temperature distribution from a lithium-ion pouch cell (20Ah capacity) is studied under different discharge rates of 1C, 2C, 3C, and 4C.
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
Journal Article
2015-01-1160
Namdoo Kim, Ayman Moawad, Neeraj Shidore, Aymeric Rousseau
Abstract Plug-in Hybrid Electric Vehicles (PHEVs) have demonstrated the potential to provide significant reduction in fuel use across a wide range of dynamometer test driving cycles. Companies and research organizations are involved in numerous research activities related to PHEVs. One of the current unknowns is the impact of driving behavior and standard test procedure on the true benefits of PHEVs from a worldwide perspective. To address this issue, five different PHEV powertrain configurations (input split, parallel, series, series-output split and series-parallel), implemented on vehicles with different all-electric ranges (AERs), were analyzed on three different standard cycles (i.e., Urban Dynamometer Driving Schedule, Highway Fuel Economy Test, and New European Driving Cycle). Component sizes, manufacturing cost, and fuel consumption were analyzed for a midsize car in model year 2020 through the use of vehicle system simulations.
2015-04-14
Technical Paper
2015-01-1158
Justin Wilbanks, Fabrizio Favaretto, Franco Cimatti, Michael Leamy
Abstract This paper presents a detailed design study and associated considerations supporting the development of high-performance plug-in hybrid electric vehicles (PHEVs). Due to increasingly strict governmental regulations and increased consumer demand, automotive manufacturers have been tasked with the reduction of fuel consumption and greenhouse gas (GHG) emissions. PHEV powertrains can provide a needed balance in terms of fuel economy and vehicle performance by exploiting regenerative braking, pure electric vehicle operation, engine load-point shifting, and power-enhancing hybrid traction modes. Thus, properly designed PHEV powertrains can reduce fuel consumption while increasing vehicle utility and performance.
2015-04-14
Technical Paper
2015-01-1155
Robert Steffan, Peter Hofmann, Bernhard Geringer
Abstract This paper focuses on the potentials of a Belt-Starter-Generator (BSG) in the context of an ultra-light vehicle prototype with a target curb weight of only 600 kg. Therefore, two hybrid approaches with a voltage level below 60 V are described and their potentials regarding electrical driving and CO2 reduction are analysed in detail. Introducing the ‘Cars Ultra-Light Technology’ (CULT) project, the holistic lightweight approach is described as a main requirement for the further hybrid investigations. In addition, a P2-hybrid structure with a 12 V BSG on the transmission input shaft enabled unique features despite the low voltage level and limited electrical power resources. The CO2 reduction for this powertrain combination is described and compared to a conventional stop start configuration. The validation process on a dynamic test rig is presented as well.
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
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
2015-01-1223
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
2015-01-1230
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
Journal Article
2015-01-1209
Zhengyu Liu, Thomas Winter, Michael Schier
Abstract This paper presents the development of a novel direct coil cooling approach which can enable high performance for electric traction motor, and in further significantly reduce motor losses. The proposed approach focuses on bypassing critical thermal resistances in motor by cooling coils directly in stator slots with oil flow. Firstly, the basic configuration and features are shown: sealed stator slots to air gap, pressure reservoirs on both side of the slots and slot channels for oil flow. The key to enhance thermal performance of the motor here is based on introducing fluid guiding structure in the slot channels. Next, heat transfer in the channel with guiding structure is investigated by CFD and compared with bare slot channel without guiding structure. For studying the effectiveness of proposed cooling concept, numerical analysis is conducted to compare it with HEV favored oil impingement cooling.
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
2015-01-1201
Mohammad Anwar, Monty Hayes, Anthony Tata, Mehrdad Teimorzadeh, Thomas Achatz
Abstract The Chevrolet Volt is an electric vehicle with extended-range that is capable of operation on battery power alone, and on engine power after depletion of the battery charge. First generation Chevrolet Volts were driven over half a billion miles in North America from October 2013 through September 2014, 74% of which were all-electric [1, 12]. For 2016, GM has developed the second-generation of the Volt vehicle and “Voltec” propulsion system. By significantly re-engineering the traction power inverter module (TPIM) for the second-generation Chevrolet Volt extended-range electric vehicle (EREV), we were able to meet all performance targets while maintaining extremely high reliability and environmental robustness. The power switch was re-designed to achieve efficiency targets and meet thermal challenges. A novel cooling approach enables high power density while maintaining a very high overall conversion efficiency.
2015-04-14
Technical Paper
2015-01-1198
Ming Cheng, Lei Feng, Bo Chen
This paper investigates the aging performance of the lithium ion cobalt oxide battery pack of a single shaft parallel hybrid electric vehicle (HEV) under different ambient temperatures. Varying ambient temperature of HEVs results in different battery temperature and then leads to different aging performance of the battery pack. Battery aging is reflected in the increasing of battery internal resistance and the decreasing of battery capacity. In this paper, a single shaft parallel hybrid electric vehicle model is built by integrating Automotive Simulation Model (ASM) from dSPACE and AutoLion-ST battery model from ECPower to realize the co-simulation of HEV powertrain in the common MATLAB/Simulink platform. The battery model is a physics-based and thermally-coupled battery (TCB) model, which enables the investigation of battery capacity degradation and aging. Standard driving cycle with differing ambient temperatures is tested using developed HEV model.
2015-04-14
Technical Paper
2015-01-1199
Zhenli Zhang, Anthony Rick, Brian Sisk
Abstract The microhybrid electric vehicle (MHEV) has increasingly received attention since it holds promise for significant increases in fuel economy vs. traditional gasoline vehicles at a lower price point than hybrid vehicles. Passive parallel connection of the traditional 12V lead acid battery and a high power lithium ion battery has been identified as a potential architecture that will facilitate fuel economy improvements with minimal changes to the electrical network. Enabling a passive dual-battery connection requires a design match between the two batteries, including characteristics such as battery size and resistance, so that the performance can be optimized. In this work we have developed a hybrid model that couples electrochemical model of lithium ion battery (NMC-Graphite as an example) and an equivalent circuit model of lead acid battery in order to study the behavior of 12V dual-battery microhybrid architectures.
2015-04-14
Technical Paper
2015-01-1197
Chao Chen, Franz Diwoky, Zoran Pavlovic, Johann Wurzenberger
This paper presents a system-level thermal model of a fluid-cooled Li-Ion battery module. The model is a reduced order model (ROM) identified by results from finite element analysis (FEA)/computational fluid dynamic (CFD) coupling simulation using the linear and time-invariant (LTI) method. The ROM consists of two LTI sub-systems: one of which describes the battery temperature response to a transient battery current, and the other of which takes into account of the battery temperature variation due to a heat flux induced by a varied inlet temperature of the battery cooling circuit. The thermal LTI model can be coupled to an electrical model to build a complete system-level battery ROM. Test examples show that the ROM is able to provide as accurate results as those from FEA/CFD coupling simulations.
2015-04-14
Technical Paper
2015-01-1204
Ji Zhang, Zhi Liao, Zechang Sun
Abstract Electromagnetic interference (EMI) is a common problem in power electronics systems. Pulse-width modulation (PWM) control of semiconductor devices in a power converter circuit creates discontinuity in voltage and current with rich harmonics over a broad frequency range, creating both conducted and radiated noise. The increase in switching speed enabled by new power semiconductor devices helps to reduce converter size and reduce switching losses, but further exacerbates the EMI problem. Complying with regulatory EMI emission limits requires the use of EMI filters in almost all power converter designs, and EMI filters are often the dominant elements for system volume, weight, and cost. Electromagnetic interference (EMI) filtering is a critical driver for volume and weight for many applications, particularly in airborne and other mobile platforms.
2015-04-14
Technical Paper
2015-01-1203
Subhashree Rajagopal, Sebastien Desharnais, Balamurugan Rathinam, Upendra Naithani
Abstract Electromagnetic brakes are found in a variety of applications. They offer tremendous advantages including: absence of fading, high braking torque and controllability. However they suffer from decreasing torque at low and high speeds. In this study, a novel concept of permanent magnet eddy-current brake is proposed that maintains a flat braking torque profile over a broad speed range. The principle is analytically investigated and numerically validated through finite element simulations using MAXWELL. It is demonstrated that a usably flat braking torque profile can be achieved by altering the path of eddy-currents by magnetic field orientation, thereby affecting the apparent rotor resistance.
2015-04-14
Technical Paper
2015-01-1202
Weimin Zhang, Saeed Anwar, Daniel J. Costinett, Fred Wang
Abstract A cost-effective SiC based hybrid switch and an improved inductor design procedure for boost converter in electric vehicles (EVs) and hybrid electric vehicles (HEVs) are presented in this paper. The feasibility of a hybrid switch using low power SiC MOSFET and high power Si IGBT is investigated to provide a cost-effective and failure-resistant method to employ the fast switching characteristics of SiC devices. The operation of the hybrid switch is tested in double pulse test experiment and compared with the single IGBT. Additionally, the boost inductor design is discussed, which allows the optimization of weight and power loss across different core materials. An improved powder core inductor design procedure is presented to avoid the iterative design procedure provided by the manufacture. Both the powder material and nanocrystalline material are considered in the inductor design procedure.
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
Journal Article
2015-01-1389
Yu Zhang, Linda Angell, Silviu Pala, Ifushi Shimonomoto
Abstract Objective tools that can assess the demands associated with in-vehicle human machine interfaces (HMIs) could assist automotive engineers designing safer interaction. This paper presents empirical evidence supporting one objective assessment approach, which compares the demand associated with in-vehicle tasks to the demand associated with “benchmarking” or “comparison tasks”. In the presented study, there were two types of benchmarking tasks-a modified surrogate reference task (SuRT) and a delayed digit recall task (n-back task) - representing different levels of visual demand and cognitive demand respectively. Twenty-four participants performed these two types of benchmarking tasks as well as two radio tasks while driving a vehicle on a closed-loop test track. Response measures included physiological (heart rate), glance metrics, driving performance (steering entropy) and subjective workload ratings.
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