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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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Regenerative Braking Control for High Level Deceleration on Low Mu Surface

SAE International Journal of Alternative Powertrains

Auto & Vehicle Mfg Tech-Witold Grzegozek
Coventry University-Keith Burnham, Navneesh Phillip
  • Journal Article
  • 2015-01-9141
Published 2015-05-01 by SAE International in United States
Hybrid and electric vehicle (H/EV) technology is already well established in the automotive industry and a great majority of car manufacturers offer vehicles with alternative propulsion systems (hybrid or electric - H/E). This advancement, however, does not mean that all technical aspects of H/E propulsion systems have already been encapsulated or even fully understood. This statement is specifically valid for regenerative braking technology. In order to regenerate the maximum possible energy, which may be limited in real applications (e.g. by the charging ratio of the energy storage device(s)), the interaction of regenerative braking and the active driving safety systems (ADSSs) such as the anti-lock braking system (ABS) needs to be taken in to account. For maximum recaptured energy via electric motor (E-Motor) braking, the use of regenerative braking, which generates decelerations greater than 0.1g, should be deployed. This however, creates the possibility of ADSS intervention which limits the extensive use of regenerative braking for the full breath of the braking period.In this paper, simulation results making use of a vehicle mathematical model are presented to…
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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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Air Compressors for Fuel Cell Vehicles: An Systematic Review

SAE International Journal of Alternative Powertrains

Shanghai Fuel Cell Vehicle Powertrain Co.-HuaiSheng Ni
Tongji Univ.-Wan Yu, Xu Sichuan
  • Journal Article
  • 2015-01-1172
Published 2015-04-14 by SAE International in United States
Even though air compressors for traditional vehicles and fuel cell vehicles (FCVs) share many similarities, a fuel cell vehicle cannot directly employ the effective and mass-produced traditional vehicles' air compressors. This is because the fuel cell vehicles have special requirements, such as oil free, low flow rate with high pressure ratio, high efficiency, and low weight and volume.In order to find suitable air compressors to match the fuel cell system (FCS)'s requirements, different air compressors' performance and physical characteristics are compared. These air compressors include screw compressor with expander, roots compressor with expander, turbocompressor, and scroll compressor with expander. The comparison and analysis is both theoretical and practical.Results show that the turbocompressor and the roots compressor/expander have higher performance compared to the others in the aspects of input power, system efficiency, weight, and volume. However, the two of them also show some defects. The turbocompressor has a limited turndown ratio due to the surge. And the roots compressor has a limited pressure ratio and pulsation characteristics.The application of air compressors in FCVs is also studied.…
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Vibration Reduction in Motors for the SPORT HYBRID SH-AWD

SAE International Journal of Alternative Powertrains

Honda R&D Co., Ltd.-Manabu Yazaki
  • Journal Article
  • 2015-01-1206
Published 2015-04-14 by SAE International in United States
A new motor has been developed that combines the goals of greater compactness, increased power and a quiet drive. This motor is an interior permanent magnet synchronous motor (IPM motor) that combines an interior permanent magnet rotor and a stator with concentrated windings.In addition, development of the motor focused on the slot combination, the shape of the magnetic circuits and the control method all designed to reduce motor noise and vibration.An 8-pole rotor, 12-slot stator combination was employed, and a gradually enlarged air gap configuration was used in the magnetic circuits. The gradually enlarged air gap brings the centers of the rotor and the stator out of alignment, changing the curvature, and continually changing the amount of air gap as the rotor rotates. The use of the gradually enlarged air gap brings torque degradation to a minimum, and significantly reduces torque fluctuation and iron loss of rotor and stator.A superposed harmonic current is used as the control method for the motor. This control method reduces torque fluctuation by adding a harmonic current component on the…
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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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