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SAE International Journal of Alternative Powertrains
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Design of an Eddy Current Torque Bypass Clutch for Seamless Automated Manual Transmissions of Electric and Hybrid Vehicles

SAE International Journal of Alternative Powertrains

Université de Sherbrooke-Gabriel Pouliot, Marc-Olivier Lacerte, Jean-Sebastien Plante, Philippe Micheau
  • Journal Article
  • 2015-01-9143
Published 2015-07-01 by SAE International in United States
This paper presents the design and experimental validation of an eddy current torque transfer clutch for use inside Automated Manual Transmissions (AMTs) to perform seamless gear upshifts. Electric vehicles (EVs) with a single-ratio gearbox may provide high levels of smoothness, but using a multi-speed gearbox provides significant benefits in terms of vehicle acceleration, top speed, powertrain cost, mass, and energy consumption. AMTs can provide smooth shifts without torque interruption when coupled to a normally-open torque bypass clutch. However, conventional dry friction clutches are not best suited for such torque bypass due to wear and controllability concerns, while wet clutches would decrease powertrain efficiency due to viscous losses. An eddy current clutch would be highly controllable, simple to manufacture, low-cost, robust, and do not wear compared to friction clutches. The potential of eddy current clutches is assessed from a representative case study consisting of a ∼190 Nm clutch for a seamless two-speed AMT. The clutch design is based upon Wouterse's model, which is further refined using a Finite Element Analysis (FEA) on the clutch magnetic circuit.…
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Consequences of Deep Cycling 24 Volt Battery Strings

SAE International Journal of Alternative Powertrains

Exide Technologies-Fred Feres
Oakland University-Henry A. Catherino
  • Journal Article
  • 2015-01-9142
Published 2015-07-01 by SAE International in United States
Deep charge and discharge cycling of 24 Volt battery strings composed of two 12 Volt VRLA batteries wired in series affects reliability and life expectancy. This is a matter of interest in vehicle power source applications. These cycles include those specific operational cases requiring the delivery of the full storage capacity during discharge. The concern here is related to applications where batteries serve as a primary power source and the energy content is an issue. It is a common practice for deep cycling a 24 volt battery string to simply add the specified limit voltages during charge and discharge for the individual 12 Volt batteries. In reality, the 12 Volt batteries have an inherent capacity variability and are not identical in their performance characteristics. The actual voltages of the individual 12 Volt batteries are not identical. The experimental measurements reveal that one of the two individual batteries in the series configuration is driven to voltages exceeding the acceptable operational limits for a single 12 Volt battery. This condition results in a loss of battery capacity…
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Analysis of Motor Vibration Isolation System with Focus on Mount Resonances for Application to Electric Vehicles

SAE International Journal of Alternative Powertrains

Ohio State University-Xianpai Zeng, Jared Liette, Scott Noll, Rajendra Singh
  • Journal Article
  • 2015-01-2364
Published 2015-06-15 by SAE International in United States
The vibration isolation effectiveness of powertrain mount configurations is examined for electric vehicle application by considering the effect introduced by internal mount resonances. Unlike internal combustion engines where mounts are typically designed only for static support and low frequency dynamics, electric motors have higher excitation frequencies in a range where mount resonances often occur. The problem is first analytically formulated by considering a simple 3-dimensional powertrain system, and the vibration isolation effectiveness significantly deteriorates at the mount resonance(s). It is shown that by modifying the mount shape, the mount resonance(s) can be shifted while maintaining the same static rate, tuning the frequency away from any engine excitation or natural frequencies. Further, internal mount resonances are utilized to improve vibration isolation over a narrow frequency range, using non-identical mounts to split mount resonance peaks. Then a computational model for a realistic drive unit (containing electric motor, power invertor, and gearbox) is considered. The mount resonance phenomenon is replicated in the computational model, and the effect on non-identical mounts is again examined. Finally, 3 and 4-point mounting…
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Methods for Measuring, Analyzing and Predicting the Dynamic Torque of an Electric Drive Used in an Automotive Drivetrain

SAE International Journal of Alternative Powertrains

Daimler AG-Dirk Lieske
IPEK-Albert Albers, Jan Fischer, Matthias Behrendt
  • Journal Article
  • 2015-01-2363
Published 2015-06-15 by SAE International in United States
The driving comfort is an important factor for buying decisions. For the interior noise of battery electric vehicles (BEV) high frequency tonal orders are characteristic. They can for example be caused by the gearbox or the electric drive and strongly influence the perception and rating of the interior noise by the customer.In this contribution methods for measuring, analyzing and predicting the excitation by the dynamic torque of the electric drive are presented. The dynamic torque of the electric drive up to 3.5 kHz is measured on a component test bench with the help of high frequency, high precision torque transducer. The analysis of the results for the order of interest shows a good correlation with the acoustic measurements inside the corresponding vehicle. In addition an experimental and numerical modal analysis of the rotor of the electric drive are performed. The torsional resonance modes are put into context of the elevation of the dynamic torque with regard to the frequency. In a further analysis the phase shifts of the torsional excitation of the different rotor segments,…
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Next Generation Voltec Electric Machines; Design and Optimization for Performance and Rare-Earth Mitigation

SAE International Journal of Alternative Powertrains

General Motors Co-Sinisa Jurkovic, Khwaja Rahman, Nitin Patel, Peter Savagian
  • Journal Article
  • 2015-01-1208
Published 2015-04-14 by SAE International in United States
This paper presents the design and performance details of electric propulsion system for GM's second generation Extended Range Electric Vehicle (EREV). First generation Chevrolet Volts have been driven over half a billion miles in North America from October 2013 through September 2014, 74% of which were all-electric. The second generation of Volt brings a significant mass reduction and increased performance, EV driving range and fuel economy while simultaneously reducing rare earth content in its traction electric motors.The electric propulsion system is built on two electric machines; both PMAC topology. While hybrid-electric vehicles are gaining in popularity in hopes of addressing cleaner, energy sustainable technology in transportation, materials sustainability and rare earth dependence mitigation has not been the first priority in the hybrids available on the market today. Design robustness to material cost volatility is crucial in automotive industry success and therefore designing electric propulsion to minimize or eliminate rare earth usage plays a major role in HEVs success. The objective of this paper is to present the newly redesigned propulsion system for added performance while…
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A Study of Potential Fuel Economy Technologies to Achieve CAFE 2025 Regulations using Fleet Simulation Modeling Software

SAE International Journal of Alternative Powertrains

MAHLE Powertrain LLC-Bernie Porter, Hugh Blaxill, Noor Jariri
  • Journal Article
  • 2015-01-1683
Published 2015-04-14 by SAE International in United States
The 2025 Corporate Average Fleet Economy (CAFE) fuel economy regulations are a significant challenge to the automotive industry. These regulations require dramatic increases in vehicle fleet fuel economy. This paper will identify and analyze a portfolio of technologies that have the potential to achieve the 2025 CAFE fuel economy targets, focusing on powertrain enhancements. The study uses a MAHLE Powertrain developed fleet modeling tool and a range of vehicle technologies and powertrain data taken from MAHLE's global research and development activities. Powertrain technologies considered include extreme engine downsizing, dilute combustion, friction reduction, hybridization, diesel and alternative fuels. The vehicle technologies analyzed include vehicle light weighting, reduced rolling resistance, advanced transmissions and improved aerodynamics.The results of this study suggest that in order to meet CAFE 2025 fleet fuel economy regulations, a combination of advanced powertrain, drivetrain and vehicle technology changes will be required.
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Thermal Management of Lithium-Ion Pouch Cell with Indirect Liquid Cooling using Dual Cold Plates Approach

SAE International Journal of Alternative Powertrains

University of Waterloo-Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
  • Journal Article
  • 2015-01-1184
Published 2015-04-14 by SAE International in United States
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. In the second part of the research, the total heat generation from a particular battery is obtained under different discharge rates (1C, 2C, 3C, and 4C) and different boundary conditions (cooling bath temperature of 5°C, 15°C, 25°C, and 35°C). In the third part of the research,…
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Degradation Analysis of Pouch Cell Using High-Energy Cathode Material for Advanced Lithium-ion Battery

SAE International Journal of Alternative Powertrains

Honda R&D Co., Ltd.-Hiroto Maeyama, Toru Sukigara
  • Journal Article
  • 2015-01-1193
Published 2015-04-14 by SAE International in United States
Lithium-rich layered oxide, expressed as xLi2MnO3-(1-x) LiMO2 (M = Ni, Co, Mn, etc.), exhibits a high discharge capacity of 200 mAh/g or more and a high discharge voltage at a charge of 4.5 V or more. Some existing reports on cathode materials state that lithium-rich layered oxide is currently the most promising candidate as an active material for high-energy-density lithium-ion cells, but there are few reports on the degradation mechanism. Therefore, this study created a prototype cell using a lithium-rich layered cathode and a graphite anode, and analyzed the degradation mechanism due to charge and discharge. In order to investigate the causes of degradation, changes in the bulk structure and surface structure of the active material were analyzed using high-resolution X-ray diffraction (HRXRD), a transmission electron microscope (TEM), X-ray absorption fine structure (XAFS), and scanning electron microscope/energy dispersive X-ray spectroscopy (SEM-EDX). The results showed that dissolution of transition metals from the cathode active material is the main factor producing degradation of the full cell capacity, and that this is promoted by excessive reductive decomposition of…
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Control Analysis and Thermal Model Development for Plug-In Hybrid Electric Vehicles

SAE International Journal of Alternative Powertrains

Argonne National Laboratory-Namwook Kim, Aymeric Rousseau, Henning Lohse-Busch
Seoul National University-Jongryeol Jeong
  • Journal Article
  • 2015-01-1157
Published 2015-04-14 by SAE International in United States
For electrified vehicles, understanding the impact of temperature on vehicle control and performances becomes more important than before because the vehicle might consume more energy than conventional vehicles due to lack of the engine waste heat. Argonne has tested many advanced vehicles and analyzed the vehicle level control based on the test data. As part of its ongoing effort, Toyota Prius Plug-in Hybrid was tested in thermal environmental chamber, and the vehicle level control and performances are analyzed by observing the test results. The analysis results show that the control of the Plug-in Hybrid Electric Vehicle (PHEV) is similar with Prius Hybrid Electric Vehicle (HEV) when the vehicle is under a charge sustaining mode, and the vehicle tries to consume the electric energy first under a charge depleting mode. This study provides information about the operating mode and the control behaviors including the change of the control and performances under cold or hot ambient temperature. In order to validate the analysis results, a vehicle model for the PHEV is developed, and the results show that…
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Model-Based Parameter Identification of Healthy and Aged Li-ion Batteries for Electric Vehicle Applications

SAE International Journal of Alternative Powertrains

Clemson Univ.-Simona Onori
Ford Motor Co.-Jimi Tjong
  • Journal Article
  • 2015-01-0252
Published 2015-04-14 by SAE International in United States
Electric vehicles are receiving considerable attention because they offer a more efficient and sustainable transportation alternative compared to conventional fossil-fuel powered vehicles. Since the battery pack represents the primary energy storage component in an electric vehicle powertrain, it requires accurate monitoring and control. In order to effectively estimate the battery pack critical parameters such as the battery state of charge (SOC), state of health (SOH), and remaining capacity, a high-fidelity battery model is needed as part of a robust SOC estimation strategy. As the battery degrades, model parameters significantly change, and this model needs to account for all operating conditions throughout the battery's lifespan. For effective battery management system design, it is critical that the physical model adapts to parameter changes due to aging.In this paper, we present an effective method for offline battery model parameter estimation at various battery states of health. An equivalent circuit with one voltage source, one resistance in series, and several RC pairs modeled the battery charging and discharging dynamics throughout the lifespan of the battery. Accelerated aging tests using…
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