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SAE International Journal of Alternative Powertrains
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Methods of Measuring Regenerative Braking Efficiency in a Test Cycle

SAE International Journal of Alternative Powertrains

Ford Motor Company-Zheng Liu, Walter J. Ortmann, Bernard Nefcy, Dan Colvin, Francis Connolly
  • Journal Article
  • 2017-01-1168
Published 2017-03-28 by SAE International in United States
In Hybrid Electric Vehicles, Regenerative Braking is an essential function to convert vehicle kinetic energy into electrical energy, which charges the battery during a braking event to make a portion of captured kinetic energy available for use later. In comparison, conventional vehicles use friction brakes only and kinetic energy is dissipated as heat and not made available for later use. This paper introduces methods of evaluating Regenerative Braking Efficiency, including multiple efficiency definitions that lead to different attributes. The paper proposes regenerative brake event definitions during the FTP cycle and how they are used for control strategy and calibration updates. Also, we apply the efficiency metrics to four different vehicles from four automotive manufacturers for comparison. The paper presents a sample comparison result. Finally, we compare our efficiency metrics with the Environmental Protection Agency (U.S.EPA) official Brake Energy Recovery efficiency evaluation process.
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Development of Multi Stage Hybrid System for New Lexus Coupe

SAE International Journal of Alternative Powertrains

AISIN AW CO., LTD.-Hideki Furuta, Yuma Mori
Toyota Motor Corporation-Shunya Kato, Ikuo Ando, Koji Ohshima, Tooru Matsubara, Yasuhiro Hiasa
  • Journal Article
  • 2017-01-1173
Published 2017-03-28 by SAE International in United States
Lexus launched the new hybrid luxury coupe LC500h in 2017 to help enhance its brand image and competitiveness for the new generation of Lexus. During the development of the LC500h, major improvements were made to the hybrid system by adopting the newly-developed Multi Stage Hybrid System, which combines a multi stage shift device with the transmission from the previous hybrid system to maximize the potential of the electrically-controlled continuously variable transmission. Optimum engine and electrical component specifications were designed for the new vehicle and transmission. As a result, the LC500h achieves a 0-to-60 mph acceleration time of 4.7 seconds, with a combined fuel economy of 30.0 mpg while satisfying SULEV emissions requirements. Two controls were constructed to help resolve the issues that arose due to adding the shift device. A model-based shift control that calculates the torque for the electrical components during shifts was established using an optimal control method. The power management control, which ensures the input and output power of the lithium-ion battery in the LC500h, was modified by applying compensators to reduce…
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Study of Oxide Supports for PEFC Catalyst

SAE International Journal of Alternative Powertrains

Toyota Motor Corporation-Tatsuya Arai, Ozaki Takashi, Kazuki Amemiya, Tsuyoshi Takahashi
  • Journal Article
  • 2017-01-1179
Published 2017-03-28 by SAE International in United States
Polymer electrolyte membrane fuel cell (PEFC) systems for fuel cell vehicles (FCVs) require both performance and durability. Carbon is the typical support material used for PEFC catalysts. However, hydrogen starvation at the anode causes high electrode potential states (e.g., 1.3 V with respect to the reversible hydrogen electrode) that result in severe carbon support corrosion. Serious damage to the carbon support due to hydrogen starvation can lead to irreversible performance loss in PEFC systems. To avoid such high electrode potentials, FCV PEFC systems often utilize cell voltage monitor systems (CVMs) that are expensive to use and install. Simplifying PEFC systems by removing these CVMs would help reduce costs, which is a vital part of popularizing FCVs. However, one precondition for removing CVMs is the adoption of a durable support material to replace carbon. For this reason, tin oxide and titanium oxide were examined as cathode and anode support materials, respectively, since these materials are more stable under high potentials than carbon. Membrane electrode assemblies (MEAs) with titanium oxide- and tin oxide-supported platinum (Pt) catalysts were…
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Development of New Plug-In Hybrid System for Compact-Class Vehicle

SAE International Journal of Alternative Powertrains

Toyota Motor Corporation-Shinji Ichikawa, Hiroaki Takeuchi, Shigeru Fukuda, Shigeki Kinomura, Yoshiki Tomita, Yosuke Suzuki, Takahiko Hirasawa
  • Journal Article
  • 2017-01-1163
Published 2017-03-28 by SAE International in United States
A next-generation plug-in hybrid system has been developed for the new Prius Prime. The objective of this development was to maximize the performance of the Toyota Hybrid System II (THS II) developed for the new fourth generation Prius HV, while achieving even better dynamic performance in electric vehicle (EV) mode. These objectives were accomplished by the adoption of new components and systems, as well as refinements to existing hybrid vehicle (HV) components. This paper describes the development of this new plug-in hybrid system.
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Brake Clutch Assisted Mode Transition Control for Compound Power-Split Vehicle

SAE International Journal of Alternative Powertrains

Corun CHS Tech. Co., Ltd.-Tong Zhang, Wentai Zhou, Huijun Cheng, Haisheng Yu
Corun CHS Tech. Co., Ltd.; Tongji University-Chen Wang
  • Journal Article
  • 2017-01-1170
Published 2017-03-28 by SAE International in United States
Because a compound power-split transmission is directly connected to the engine, dramatic fluctuations in engine output torque result in strong jerks and torque losses when the hybrid vehicle is in mode transition from electric drive mode to hybrid drive mode. In order to enhance ride comfort and reduce the output torque gap during mode transition process, a brake clutch assisted coordinated control strategy was developed. Firstly, the dynamic plant model of the power-split vehicle including driveline model, engine ripple torque and brake clutch torque was deduced. Secondly, the brake clutch assisted mode transition process was analyzed, and the output torque capability was compared between cases of both brake clutch assisted and unassisted mode transition process. Thirdly, a coordinated control strategy was designed to determine the desired motor torque, brake clutch torque, engine torque, and the moment of fuel injection. Finally, the effectiveness of coordinated control strategy was verified by vehicle test. The experimental results indicate that the proposed strategy was effective to suppress driveline speed oscillations during engine cranking phase, and reduce the engine cranking…
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Seasonality Effect on Electric Vehicle Miles Traveled in Electrified Vehicles

SAE International Journal of Alternative Powertrains

Ford Motor Company-N. Khalid Ahmed, Jimmy Kapadia
  • Journal Article
  • 2017-01-1146
Published 2017-03-28 by SAE International in United States
The efficiency of an electrified powertrain is sensitive to fluctuations in temperature. This impacts the Electric Vehicle Miles Traveled (eVMT), or the miles travelled by Plug-In Hybrid Electric Vehicles (PHEVs) using electrical grid power. In this paper, we discuss various methods used to calculate eVMT for PHEVs and propose an alternate method to calculate eVMT with higher accuracy using real world customer data. Real world customer data is obtained through telematics modems on Ford Energi products powered by the “MyFord Mobile” web and phone applications. Customer and season specific data from pure charge depleting and pure charge sustaining trips are used in this method to generate a customer and season specific conversion factor. As a result, this real world data based method helps track the effect of seasonality on eVMT obtained by customers in a combination of all charge depleting and charge sustaining trips.
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Powersplit or Parallel - Selecting the Right Hybrid Architecture

SAE International Journal of Alternative Powertrains

Ford Motor Company-Jimmy Kapadia, Daniel Kok, Mark Jennings, Ming Kuang, Brandon Masterson, Richard Isaacs, Alan Dona, Chuck Wagner, Thomas Gee
  • Journal Article
  • 2017-01-1154
Published 2017-03-28 by SAE International in United States
The automotive industry is rapidly expanding its Hybrid, Plug-in Hybrid and Battery Electric Vehicle product offerings in response to meet customer wants and regulatory requirements. One way for electrified vehicles to have an increasing impact on fleet-level CO2 emissions is for their sales volumes to go up. This means that electrified vehicles need to deliver a complete set of vehicle level attributes like performance, Fuel Economy and range that is attractive to a wide customer base at an affordable cost of ownership.As part of “democratizing” the Hybrid and plug-In Hybrid technology, automotive manufacturers aim to deliver these vehicle level attributes with a powertrain architecture at lowest cost and complexity, recognizing that customer wants may vary considerably between different classes of vehicles. For example, a medium duty truck application may have to support good trailer tow whereas a C-sized sedan customer may prefer superior city Fuel Economy. This difference in attribute wants can drive the need for different electrified architectures. Here, two commonly used Hybrid and Plug-in Hybrid Electric Vehicle architectures can be distinguished: Powersplit and…
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Development of Multi Stage Hybrid Transmission

SAE International Journal of Alternative Powertrains

AISIN AW Co.,LTD.-Tomoo Atarashi, Ryuta Horie
Toyota Motor Corporation-Koichi Okuda, Yuji Yasuda, Masatoshi Adachi, Atsushi Tabata, Haruhisa Suzuki, Kiyonori Takagi
  • Journal Article
  • 2017-01-1156
Published 2017-03-28 by SAE International in United States
Toyota Motor Corporation developed the Multi Stage Hybrid System for the Lexus flagship LC500h coupe with the aim of achieving an excellent balance between fuel economy and acceleration performance. The Multi Stage Hybrid Transmission used in this new hybrid system includes a shift device located immediately after the power split device and motor.Compared with previous hybrid systems, acceleration performance is improved by increasing the driving force at low and medium vehicle speeds in lower gears, fuel economy and heat management performance are improved by reducing electrical loss by selecting the optimal gear depending on the driving state. The Multi Stage Hybrid Transmission uses a shift device with a wide gear ratio range to maximize both fuel economy and acceleration performance.The transmission was designed to achieve the appropriate size to be mounted in a new platform, as well as class-leading low noise levels for adoption in luxury vehicles. It also includes a quickly responsive and accurate hydraulic control system that achieves excellent shift performance.This paper describes the hardware of the Multi Stage Hybrid Transmission.
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Generation of Replacement Vehicle Speed Cycles Based on Extensive Customer Data by Means of Markov Models and Threshold Accepting

SAE International Journal of Alternative Powertrains

Daimler AG-Klaus Lüpkes
TU Dresden-Roman Liessner, Ansgar Dietermann, Bernard Bäker
  • Journal Article
  • 2017-26-0256
Published 2017-01-10 by SAE International in United States
The reduction of fuel consumption as well as the rising demands of customers regarding a vehicle’s driving dynamic and the legislator’s continually rising demands are a current issue in vehicle development. Hybrid vehicles offer a possibility to rise to this challenge. Realistic driving cycles are of utmost importance for the calibration of a hybrid vehicle’s operational strategy. Deriving replacement speed cycles from extensive customer data sets seems to be an approach for solving these problems. The contribution at hand describes the derivation of replacement cycles by using stochastic models, probabilistic (weighted) drawings and a combinatorial optimisation. The novelty value is that the characteristic influences of all drivers are being considered in the generation due to the stochastic modelling. The newly developed algorithm extracts frequently reoccurring patterns from the stochastic model and then assembles several generated velocity progressions to one replacement cycle which combines characteristics which are important for consumption and are also customer-oriented. The contained combinatorial optimisation is based on an optimisation algorithm called "threshold accepting" and is an innovation for this usage scenario. Studies…
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Electric Vehicles Energy Efficient Routing Using Ant Colony Optimization

SAE International Journal of Alternative Powertrains

Amazon Web Services, Palo Alto, CA-Romi Boimer
Gotion, Inc., Fremont, CA-Rami Abousleiman
  • Journal Article
  • 2017-01-9075
Published 2017-04-11 by SAE International in United States
Growing concerns about the environment, energy dependency, and the unstable fuel prices have increased the sales of electric vehicles. Energy-efficient routing for electric vehicles requires novel algorithmic challenges because traditional routing algorithms are designed for fossil-fueled vehicles. Negative edge costs, battery power and capacity limits, vehicle parameters that are only available at query time, alongside the uncertainty make the task of electric vehicle routing a challenging problem. In this paper, we present a solution to the energy-efficient routing problem for electric vehicles using ant colony optimization. Simulation and real-world test results demonstrate savings in the energy consumption of electric vehicles when driven on the generated routes. Real-world test results revealed more than 9% improvements in the energy consumption of the electric vehicle when driven on the recommended route rather than the routes proposed by Google Maps and MapQuest.
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