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SAE International Journal of Alternative Powertrains
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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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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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Power Dense and Robust Traction Power Inverter for the Second-Generation Chevrolet Volt Extended-Range EV

SAE International Journal of Alternative Powertrains

Delphi Electronics & Safety-Monty Hayes
General Motors Corporation-Mohammad Anwar, Anthony Tata, Mehrdad Teimorzadeh, Thomas Achatz
  • Journal Article
  • 2015-01-1201
Published 2015-04-14 by SAE International in United States
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.
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Direct Coil Cooling of a High Performance Switched Reluctance Machine (SRM) for EV/HEV Applications

SAE International Journal of Alternative Powertrains

German Aerospace Center DLR-Michael Schier
Robert Bosch GmbH-Thomas Winter
  • Journal Article
  • 2015-01-1209
Published 2015-04-14 by SAE International in United States
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. Finally, thermal performance of the proposed cooling approach is verified and compared with water/glycol jacket cooling on a switched reluctance machine prototype for EV application inside a public funded project ODIN.
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Development of Compact and High-Performance Fuel Cell Stack

SAE International Journal of Alternative Powertrains

Nippon Soken Inc.-Yuji Ishikawa
Toyota Motor Corporation-Norishige Konno, Seiji Mizuno, Hiroya Nakaji
  • Journal Article
  • 2015-01-1175
Published 2015-04-14 by SAE International in United States
Toyota Motor Corporation (TMC) has been developing fuel cell (FC) technology since 1992, and finally “MIRAI” was launched in 15th Dec. 2014. An important step was achieved with the release of the “FCHV-adv” in 2008. It established major improvements in efficiency, driving range, durability, and cold start capability. However, enhancing performance and further reductions in size and cost are required to facilitate the commercial widespread adoption of fuel cell vehicles (FCVs). TMC met these challenges by developing the world's first FC stack without a humidifying system. This was achieved by the development of an innovative cell flow field structure and membrane electrode assembly (MEA), enabling a compact and high-performance FC stack. Other cost reduction measures incorporated by the FC stack include reducing the amount of platinum in the catalyst by two-thirds and adopting a carbon nano-coating for the separator surface treatment.In the newly developed humidifier-less system, water management in each cell plays a key role in enhancing the performance. This requires measures to ensure proton conductivity and restrict the inhibition of gas diffusion.The new FC…
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A Mechanical Regenerative Brake and Launch Assist using an Open Differential and Elastic Energy Storage

SAE International Journal of Alternative Powertrains

Stress Engineering Services Inc-Christoph Gillum
University of Dayton-David H. Myszka, Andrew Murray, Kevin Giaier, Vijay Krishna Jayaprakash
  • Journal Article
  • 2015-01-1680
Published 2015-04-14 by SAE International in United States
Regenerative brake and launch assist (RBLA) systems are used to capture kinetic energy while a vehicle decelerates and subsequently use that stored energy to assist propulsion. Commercially available hybrid vehicles use generators, batteries and motors to electrically implement RBLA systems. Substantial increases in vehicle efficiency have been widely cited. This paper presents the development of a mechanical RBLA that stores energy in an elastic medium. An open differential is coupled with a variable transmission to store and release energy to an axle that principally rotates in a single direction. The concept applies regenerative braking technology to conventional automobiles equipped with only an internal combustion engine where the electrical systems of hybrid vehicles are not available. Governing performance equations are formulated and design parameters are selected based on an optimization of the vehicle operation over a simulated urban driving cycle. The functionality of this elastically-based regenerative brake device has been demonstrated on a physical prototype.
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Quantification of Drive Cycle's Rapid Speed Fluctuations Using Fourier Analysis

SAE International Journal of Alternative Powertrains

Clemson-ICAR-Zifan Liu, Andrej Ivanco, Zoran Filipi
  • Journal Article
  • 2015-01-1213
Published 2015-04-14 by SAE International in United States
This paper presents a new way to evaluate vehicle speed profile aggressiveness, quantify it from the perspective of the rapid speed fluctuations, and assess its impact on vehicle fuel economy. The speed fluctuation can be divided into two portions: the large-scale low frequency speed trace which follows the ongoing traffic and road characteristics, and the small-scale rapid speed fluctuations normally related to the driver's experience, style and ability to anticipate future events. The latter represent to some extent the driver aggressiveness and it is well known to affect the vehicle energy consumption and component duty cycles. Therefore, the rapid speed fluctuations are the focus of this paper. Driving data collected with the GPS devices are widely adopted for study of real-world fuel economy, or the impact on electrified vehicle range and component duty cycles. However, the accompanying signal noise poses a challenge, and needs to be separated from realistic rapid speed fluctuations. Filtering is commonly used, but aggressive smoothing technique can lead to loss of useful driving information. In contrast, mild smoothing technique can lead…
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Synthesis of a Hybrid-Observer-Based Active Controller for Compensating Powetrain Backlash Nonlinearity of an Electric Vehicle during Regenerative Braking

SAE International Journal of Alternative Powertrains

State Key Lab of ASE, Tsinghua Univ.-Chen Lv, Junzhi Zhang, Yutong Li, Ye Yuan
  • Journal Article
  • 2015-01-1225
Published 2015-04-14 by SAE International in United States
Regenerative braking provided by an electric powertrain is far different from conventional friction braking with respect to the system dynamics. During regenerative decelerations, the nonlinear powertrain backlash would excite driveline oscillations, deteriorating vehicle drivability and blended brake performance. Therefore, backlash compensation is worthwhile researching for an advanced powertrain control of electrified vehicles during regenerative deceleration.In this study, a nonlinear powertrain of an electric passenger car equipped with a central motor is modeled using hybrid system approach. The effect of powertrain backlash gap on vehicle drivability during regenerative deceleration is analyzed. To further improve an electric vehicle's drivability and blended braking performance, an active control algorithm with a hierarchical architecture is studied for powertrain backlash compensation. Since the backlash in driveline is unable to be measured by a sensor, a high-level hybrid observer for backlash identification is designed at first. Then, based on the observation of the backlash traverse, a low-level switching-based active controller for powertrain backlash compensation is synthesized.The proposed control algorithm is simulated and compared with a non-active baseline strategy under regeneration deceleration. The…
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Fuel Consumption and Cost Potential of Different Plug-In Hybrid Vehicle Architectures

SAE International Journal of Alternative Powertrains

Argonne National Laboratory-Namdoo Kim, Ayman Moawad, Neeraj Shidore, Aymeric Rousseau
  • Journal Article
  • 2015-01-1160
Published 2015-04-14 by SAE International in United States
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. These configurations represent typical mass-production vehicles, including the Toyota Prius PHEV, Chevrolet Volt, and Honda Accord PHEV.In addition, this study examined the impact of the transmission mechanical losses, and especially the planetary gear losses, modeled using power split ratio analysis. The powertrain…
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