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SAE International Journal of Alternative Powertrains
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Compression Ratio Control of Free Piston Linear Generator with In-Cylinder Pressure Feedforward

SAE International Journal of Alternative Powertrains

Tongji University-Lianlian Lin, Zhe Wang, Pengfei Zang
  • Journal Article
  • 08-07-02-0008
Published 2018-06-28 by SAE International in United States
The free piston linear generator (FPLG) is a novel machine that functions as an Auxiliary Power Unit (APU) for hybrid electric vehicles, which contains two opposed free piston engines and one linear generator between them. FPLG has attracted extensive interest for its potential advantages in terms of high power density and multi-fuel flexibility. The guarantee of FPLG generating electricity steadily and efficiently is the high controllability of compression ratio. In this article, a control-oriented discrete-time model was established based on Otto cycle. Since the fluctuation of in-cylinder pressure caused by instable fuel injection mass and combustion process is the main disturbance, a composite controller is designed to precisely control the compression ratio of FPLG. The composite controller is made up of a feedforward controller and a feedback tracking controller. Finally, the control performance of the composite controller and a general proportional-integral (PI) controller was compared by simulation. The simulation results indicate that the composite controller shows better performance in transient process when fuel injection mass or reference compression ratio changes suddenly. Furthermore, the standard deviation…
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Electric Vehicle with Multi-Speed Transmission: A Review on Performances and Complexities

SAE International Journal of Alternative Powertrains

Swinburne University of Technology, Australia-Md Ragib Ahssan, Mehran Motamed Ektesabi, Saman Asghari Gorji
  • Journal Article
  • 08-07-02-0011
Published 2018-12-04 by SAE International in United States
Electric vehicles (EVs) with multi-speed transmission offer improved performances compared to those with single speed transmission system in terms of top speed, fast acceleration, or gradeability along with driving range. In this study, relevant literature is extensively analyzed to explore the performances and associated complexities with multi-speed automatic manual/mechanical transmission (AMT) system in EVs. In EV powertrain, the only torque generator component is electric motor, which is not equally efficient throughout wider speed range. To the other end, vehicles need to run at different speeds in diverse driving conditions. The study shows that multi-speed transmission system enables efficient operation of electric motor by choosing an appropriate gear at different driving torque-speed demands and thus contributes to achieve desired vehicle performances at minimum energy consumption. To demonstrate the differences, both dynamic and economic performances with multi-gear system and single speed system are compared, and the results of various techniques are presented in the form of tables and bar charts. A quantitative analysis is also conducted to show the performance improvement achievable by employing multi-speed transmission concept…
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Combined Battery Design Optimization and Energy Management of a Series Hybrid Military Truck

SAE International Journal of Alternative Powertrains

Clemson University, USA-Zifan Liu, Abdullah-Al Mamun Mamun
Stanford University, USA-Simona Onori
  • Journal Article
  • 08-07-02-0010
Published 2018-10-31 by SAE International in United States
This article investigates the fuel savings potential of a series hybrid military truck using a simultaneous battery pack design and powertrain supervisory control optimization algorithm. The design optimization refers to the sizing of the lithium-ion battery pack in the hybrid configuration. The powertrain supervisory control optimization determines the most efficient way to split the power demand between the battery pack and the engine. Despite the available design and control optimization techniques, a generalized mathematical formulation and solution approach for combined design and control optimization is still missing in the literature. This article intends to fill that void by proposing a unified framework to simultaneously optimize both the battery pack size and power split control sequence. This is achieved through a combination of genetic algorithm (GA) and Pontryagin’s minimum principle (PMP) where the design parameters are integrated into the Hamiltonian function. As GA and PMP are global optimization methodologies under suitable conditions, the solution can be considered as a benchmark for the application under study. Five military drive cycles are used to evaluate the proposed approach.…
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Development of a Catalytic Converter Cool-Down Model to Investigate Intermittent Engine Operation in HEVs

SAE International Journal of Alternative Powertrains

The University of Alabama, USA-Karissa Young, Ryan Jones, A.J. Hamley, Josh Stoddard, Travis Foust, Paul Puzinauskas, Hwan-Sik Yoon
  • Journal Article
  • 08-07-02-0009
Published 2018-10-29 by SAE International in United States
Catalytic converters, a primary component in most automotive emissions control systems, do not function well until they are heated substantially above ambient temperature. As the primary energy for catalyst heating comes from engine exhaust gases, plug-in hybrid electric vehicles (PHEVs) that have the potential for short and infrequent use of their onboard engine may have limited energy available for catalytic converter heating. This article presents a comparison of multiple hybrid supervisory control strategies to determine the ability to avoid engine cold starts during a blended charge-depleting propulsion mode. Full vehicle and catalytic converter simulations are performed in parallel with engine dynamometer testing in order to examine catalyst temperature variations during the course of the US06 City drive cycle. Emissions and energy consumption (E&EC) calculations are also performed to determine the effective number of engine starts during the drive cycle.
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Multi-Attribute, System-Level Design Process for Automotive Powertrain Electric Drives: An Integrated Approach

SAE International Journal of Alternative Powertrains

Siemens Industry Software-Cassio T. Faria
Technical University of Cluj-Napoca (TUCN)-Sebastian Ciceo, Claudia Martis
  • Journal Article
  • 08-07-02-0007
Published 2018-06-05 by SAE International in United States
This article presents an electric drive powertrain design and virtual integration methodology in the context of electric vehicle systems. In the first stage, using the Model-Based System Engineering paradigm, the electric vehicle performance requirements are translated into electric drive target specifications using a system-level vehicle model. Subsequently, a functional electric drive subsystem-level model is developed based on magnetic co-energy and iron losses data obtained from a reference electric machine design. The functional electric drive model is scaled in order to meet the requested specifications, and it is coupled with different 1D (i.e. lumped-parameter) multi-physics sub-models that are later integrated into the electric vehicle system-level model. At the electric drive level the torque ripple and Noise, Vibration and Harshness characteristics are analyzed. At the vehicle level the energy consumption, thermal behavior, and mechanical performances are determined with reduced computational time. The proposed approach allows for early assessment of multiple attributes and enables designers to make decisions supported by accurate system-level simulations.
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Investigation of a Six-Phase Interior Permanent Magnet Synchronous Machine for Integrated Charging and Propulsion in EVs

SAE International Journal of Alternative Powertrains

Indian Institute of Engineering Science and Technology-Kaushik Mukherjee
University of Windsor-Lakshmi Varaha Iyer, Chunyan Lai, Himavarsha Dhulipati, Shruthi Mukundan, Narayan Kar
  • Journal Article
  • 08-07-02-0006
Published 2018-04-17 by SAE International in United States
Merits such as reduced weight, overall and operational costs of the electric vehicle (EV) while providing level 3 charging capability, are propelling research on integrated charging (IC) technology for EVs. Since the same interior permanent magnet synchronous machine (IPMSM) is used during IC and traction conditions, it is important to understand the behavior of the machine during these conditions and optimally design the machine. Hence, firstly, this paper presents a case study on performance of a laboratory 3-phase IPMSM under IC and traction conditions. Thereafter, understanding the challenges such as low magnet operating point, losses and torque oscillation in 3-phase IPMSM during IC, a 6-phase IPMSM with an unconventional configuration is investigated to yield traction characteristics like that of the 3-phase IPMSM and mitigate challenges during IC. In the process, mathematical model of the 6-phase IPMSM is developed employing the dq-axis theory. The developed model is then employed to exclusively derive the relation between various per-unitized machine parameters to obtain optimal performance under IC and traction conditions. Thereafter, a novel bottom-up machine design methodology based…
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