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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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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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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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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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Reduction of Cranking Noise from High Voltage Starter for One-Motor Two-Clutch Hybrid Systems

SAE International Journal of Alternative Powertrains

DENSO Corporation-Kousuke Baba, Yuuki Kubo, Toyoji Yagi, Akihiro Imura
  • Journal Article
  • 2017-01-1167
Published 2017-03-28 by SAE International in United States
In this paper, we propose a high voltage brushless AC starter that contributes to improved fuel efficiency and a reduction in the cost of the one-motor two-clutch hybrid system, which we call a 1MG2CL system. We have named it the HV starter, and it is composed of an AC motor, inverter and pinion with a shift mechanism. One of the issues with the 1MG2CL system is the high electrical energy when starting an ICE as it switches over from EV drive to HEV drive. While the ICE is starting, the main motor has to crank the ICE via the clutch; the clutch slips to absorb the main motor power, so the main motor has to output a high power to overcome the loss. Therefore, to contribute to reducing the electrical power by eliminating clutch slip losses, we developed an HV starter as a dedicated ICE starting device. Thanks to the reduction in electrical power, the HV starter is able to improve fuel efficiency and reduce system costs.However, the major issue is the cranking noise generated…
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Development of New IGBT to Reduce Electrical Power Losses and Size of Power Control Unit for Hybrid Vehicles

SAE International Journal of Alternative Powertrains

Toyota Central R&D Labs Inc-Sachiko Kawaji, Satoru Machida
Toyota Motor Corporation-Keisuke Kimura, Tasbir Rahman, Tadashi Misumi, Takeshi Fukami, Masafumi Hara
  • Journal Article
  • 2017-01-1244
Published 2017-03-28 by SAE International in United States
One way to improve the fuel efficiency of HVs is to reduce the losses and size of the Power Control Unit (PCU). To achieve this, it is important to reduce the losses of power devices (such as IGBTs and FWDs) used in the PCU since their losses account for about 20% of the total loss of an HV. Furthermore, another issue when reducing the size of power devices is ensuring the thermal feasibility of the downsized devices. To achieve the objectives of the 4th generation PCU, the following development targets were set for the IGBTs: reduce power losses by 19.8% and size by 30% compared to the 3rd generation. Power losses were reduced by the development of a new Super Body Layer (SBL) structure, which improved the trade-off relationship between switching and steady-state loss. This trade-off relationship was improved by optimizing the key SBL concentration parameter. Size was reduced by adopting a new environment-friendly IGBT surface electrode structural design that enabled double-sided solder packaging. This approach ensured thermal feasibility caused by the higher current density…
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Design of a Calorimeter for Measurement of Heat Generation Rate of Lithium Ion Battery Using Thermoelectric Device

SAE International Journal of Alternative Powertrains

Auburn Univ.-Song-Yul Choe
Auburn University-Yilin Yin, Zhong Zheng
  • Journal Article
  • 2017-01-1213
Published 2017-03-28 by SAE International in United States
Analysis of thermal behavior of Lithium ion battery is one of crucial issues to ensure a safe and durable operation. Temperature is the physical quantity that is widely used for analysis, but limited for accurate investigations of behavior of heat generation of battery because of sensitivities affected by heat transfer in experiments. Calorimeter available commercially is widely used to measure the heat generation of battery, but does not follow required dynamics because of a relatively large thermal time constant given by cavity and a limited heat transfer capability. In this paper, we proposed a highly dynamic calorimeter that was constructed using two thermoelectric devices (TEMs). For the design of the calorimeter and its calibration, a printed circuit board (PCB) with the same size as the battery was used as a dummy load to generate controlled heat. Dynamics were improved using a lead-lag compensator for temperature control and heat generation was estimated using Kalman filter based on a thermal model of the calorimeter. All parameters were optimized using the PCB. Finally, heat generation rate of a…
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Internal Cell Temperature Measurement and Thermal Modeling of Lithium Ion Cells for Automotive Applications by Means of Electrochemical Impedance Spectroscopy

SAE International Journal of Alternative Powertrains

Ruhr-University Bochum-Peter Haussmann, Joachim Melbert
  • Journal Article
  • 2017-01-1215
Published 2017-03-28 by SAE International in United States
Battery safety is the most critical requirement for the energy storage systems in hybrid and electric vehicles. The allowable battery temperature is limited with respect to the battery chemistry in order to avoid the risk of thermal runaway. Battery temperature monitoring is already implemented in electric vehicles, however only cell surface temperature can be measured at reasonable cost using conventional sensors. The internal cell temperature may exceed the surface temperature significantly at high current due to the finite internal electrical and thermal cell resistance. In this work, a novel approach for internal cell temperature measurement is proposed applying on board impedance spectroscopy. The method considers the temperature coefficient of the complex internal cell impedance. It can be observed by current and voltage measurements as usually performed by standard battery management systems. The relevant frequency range considered for temperature measurements is chosen for high sensitivity and robust behavior and takes state of charge variations as well as aging effects into account. Transient temperature variations caused by various load profiles are analyzed in order to characterize the…
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