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SAE International Journal of Alternative Powertrains
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Torque Ripple Description and Its Suppression through Flux Linkage Reconstruction

SAE International Journal of Alternative Powertrains

School of Automotive Studies, Tongji-Zaimin Zhong, Junjie Li, Shuihua Zhou, Yingkun Zhou, Shang Jiang
  • Journal Article
  • 2017-01-9077
Published 2017-06-17 by SAE International in United States
Description of PMSM torque in high accuracy is critical and previous work for its further research. However, the traditional linear torque model fails to describe its non-ideal characteristics of practical working. This paper presents a generalized torque model of PMSM based on flux linkage reconstruction. In synchronous rotating space coordinates, flux linkage were reconstructed through Fourier series expansion and bivariate polynomial. Based on this model, a precise PMSM torque ripple description and corresponding suppression method were developed. Current feed-forward compensation and the rotor field oriented control were applied in torque ripple suppression. Simulation and experimental results both show that the model not only accurately describes the nonlinear variation of PMSM torque in different working conditions, but also can be used to suppress PMSM torque ripple effectively.
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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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A Smart Gate Driver with Active Switching Speed Control for Traction Inverters

SAE International Journal of Alternative Powertrains

Ford Motor Company-Yan Zhou, Lihua Chen, Shuitao Yang, Fan Xu, Mohammed Khorshed Alam
  • Journal Article
  • 2017-01-1243
Published 2017-03-28 by SAE International in United States
The IGBTs are dominantly used in traction inverters for automotive applications. Because the Si-based device technology is being pushed to its theoretical performance limit in such applications during recent years, the gate driver design is playing a more prominent role to further improve the traction inverter loss performance. The conventional gate driver design in traction inverter application needs to consider worst case scenarios which adversely limit the semiconductor devices' switching speed in its most frequent operation regions. Specifically, when selecting the gate resistors, the IGBT peak surge voltage induced by fast di/dt and stray inductance must be limited below the device rated voltage rating under any conditions. The worst cases considered include both highest dc bus voltage and maximum load current. However, the traction inverter operates mainly in low current regions and at bus voltage much lower than the worst case voltage. This paper proposes a low-cost and simple gate driver circuit that can actively adjust the turn-off switching speed based on IGBT current levels. The proposed circuit utilizes the current sensing pin which is…
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Self-Excited Wound-Field Synchronous Motors for xEV

SAE International Journal of Alternative Powertrains

DENSO Corporation-Masahiro Seguchi
  • Journal Article
  • 2017-01-1249
Published 2017-03-28 by SAE International in United States
Compact, high efficiency and high reliability are required for an xEV motor generator. IPM rotors with neodymium magnets are widely applied for xEV motors to achieve these requirements. However, neodymium magnet material has a big impact on motor cost and there is supply chain risk due to increased usage of these rare earth materials for future automotive xEV’s. On the other hand, a wound-field rotor does not need magnets and can achieve equivalent performance to an IPM rotor. However, brushes are required in order to supply current to the winding coil of the rotor. This may cause insulation issues on xEV motors which utilize high voltage and high currents. Therefore, it is suggested to develop a system which supplies electric energy to the rotor field winding coil from the stator without brushes by applying a transformer between stator coil and rotor field winding. Specifically, add auxiliary magnetic poles between each field winding pole and wind sub-coils to these poles. The magnetic flux generated from the stator induces a field current in the sub-coils. Rectifying the…
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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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More Efficient Inductive Electric Vehicle Charger: Using Autonomy to Improve Energy Efficiency

SAE International Journal of Alternative Powertrains

GE Critical Power-Edward C. Fontana, Rick Barnett, Robert Catalano, James Harvey, Jiacheng He, George Ottinger, John Steel
  • Journal Article
  • 2017-01-1216
Published 2017-03-28 by SAE International in United States
Electric cars can help cities solve air quality problems, but drivers who live in apartments have no convenient way to charge daily, absent the well-controlled private garages where most electric vehicles (EVs) are currently charged each night. Environmentally robust, hands-free, inductive chargers would be ideal, but energy efficiency suffers. We asked whether the precise parking alignment provided by self-driving cars could be used to provide convenient inductive charging with improved charging efficiencies.To answer this question, we split an inductor-inductor-capacitor (LLC) battery charger at the middle of the isolation transformer. The power factor correction, tank elements, and transformer primary windings are stationary, while the transformer secondary, rectifiers, and battery control logic are on the vehicle. The transformer is assembled each time the EV parks. A variety of transformers were tested for efficient energy transfer coincident with spacing to accommodate insulation on both the charger and vehicle side of the interface. Testing with different transformer parameters demonstrate a wall to battery energy efficiency of 95%, comparable to an onboard charger.A hands-free, inductive, battery charger can deliver charging…
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CAE Method for Evaluating Mechanical Performance of Battery Packs under Mechanical Shock Testing

SAE International Journal of Alternative Powertrains

Ford Motor Company-Yongcai Wang, Rajaram Subramanian, Sarav Paramasivam, George Garfinkel
  • Journal Article
  • 2017-01-1193
Published 2017-03-28 by SAE International in United States
Mechanical shock tests for lithium metal and lithium-ion batteries often require that each cell or battery pack be subjected to multiple shocks in the positive and negative directions, of three mutually perpendicular orientations. This paper focuses on the no-disassembly requirement of those testing conditions and on the CAE methodology specifically developed to perform this assessment.Ford Motor Company developed a CAE analysis method to simulate this type of test and assess the possibility of cell dislodging. This CAE method helps identify and diagnose potential failure modes, thus guiding the Design Team in developing a strategy to meet the required performance under shock test loads. The final CAE-driven design focuses on the structural requirement and optimization, and leads to cost savings without compromising cell or pack mechanical performance. As an example, this method is applied to Ford Motor Company’s current generation of air-cooled, prismatic cell lithium-ion Plug-in Hybrid Electric Vehicles (PHEVs). Physical testing performed on the final optimized design correlated well with the CAE results thus providing validity to the simulation methodology.
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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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Electrochemical Modeling of Lithium Plating of Lithium Ion Battery for Hybrid Application

SAE International Journal of Alternative Powertrains

Johnson Controls-Zhenli Zhang
Johnson Controls Inc-Perry Wyatt
  • Journal Article
  • 2017-01-1201
Published 2017-03-28 by SAE International in United States
Lithium plating is an important failure factor for lithium ion battery with carbon-based anodes and therefore preventing lithium plating has been a critical consideration in designs of lithium ion battery and battery management system. The challenges are: How to determine the charging current limits which may vary with temperature, state of charge, state of health, and battery operations? Where are the optimization rooms in battery design and management system without raising plating risks? Due to the complex nature of lithium plating dynamics it is hard to detect and measure the plating by any of experimental means.In this work we developed an electrochemical model that explicitly includes lithium plating reaction. It enables both determination of plating onset and quantification of plated lithium. We have studied the effects of charging pulses on homogenous plating in order to provide guidance for lithium ion battery design in hybrid applications. By simulation a quantitative analysis of influencing factors on plating and a quantitative map of current limits to prevent lithium plating are provided. Our simulation suggests that a method that…
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