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A Theoretical and Experimental Analysis of the Coulomb Counting Method and Estimation of the Electrified-Vehicles Electricity Balance Over the WLTP

European Commission Joint Research-Alessandro Tansini, Georgios Fontaras
Politecnico di Torino-Federico Millo
  • Technical Paper
  • 2020-37-0020
To be published on 2020-06-23 by SAE International in United States
The energy storage devices of electrified vehicles (Hybrid Electric Vehicles and Battery Electric Vehicles) are required to operate with highly dynamic current and power outputs, both for charging and discharging operation. When calculating the vehicle CO2 emissions and electrical energy consumption from a trip, the change in electrical energy content at vehicle-level has to be accounted for. This quantity, referred to as the electricity balance in the WLTP regulation, is normally obtained through a time-integration of the current or power supplied by the vehicle batteries during operation and the efficiency factor is often assumed to be unitary (as in the official type-approval procedure). The Joint Research Centre has collected experimental data from different electrified vehicles with regards to electrical energy use and battery State Of Charge (SOC) profile; the latter was used as a reference to quantify the actual vehicle electricity balance from a trip or driving cycle. In this work, the approach of using a simple Coulomb counting method with unitary efficiency for charging and discharging for the quantification of the vehicle electricity balance…
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Bench-marking Computational Performance of Dynamic Programming For Speed Profiling and Fuel Efficiency of Autonomous-capable HEV

Ohio State University-Wilson Perez, Amit Ruhela, Punit Tulpule
  • Technical Paper
  • 2020-01-0968
To be published on 2020-04-14 by SAE International in United States
Dynamic programming has been used for optimal control of hybrid powertrain and vehicle speed optimization particularly in design phase for over a couple of decades. With the advent of autonomous and connected vehicle technologies, automotive industry is getting closer to implementing predictive optimal control strategies in real time applications. The biggest challenge in implementation of optimal controls is the limitation on hardware which includes processor speed, IO speed, and random access memory. Due to the use of autonomous features, modern vehicles are equipped with better onboard computational resources. In this paper we present a comparison between multiple hardware options for dynamic programming. The optimal control problem considered, is the optimization of travel time and fuel economy by tuning the torque split ratio and vehicle speed while maintaining charge sustaining operation. The system has two states - battery state of charge and vehicle speed, and two inputs namely, total torque and torque split ratio. First, we develop a Matlab® based program to solve the optimal control problem. The Matlab® code is optimized for performance and memory…
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Vehicle Design Considerations Enabling High-Performance Charging

Magna Steyr Fahrzeugtechnik AG & Co. KG-Christian Josef Paar, Helmut Martin Waser, Heimo Kreimaier, Inés Cuenca-Jaen, Florian Eibler
  • Technical Paper
  • 2020-01-1440
To be published on 2020-04-14 by SAE International in United States
Customer requirements such as range anxiety and charging time are the driver for increasing the charging power of battery-electric vehicles (BEV). High-performance charging (HPC) theoretically enables time targets of faster than 30 kilometers (19 miles) recharging per minute. Due to physical limitations (i.e., current limits of the components) a charging power of more than 200 kilowatt arises the question of the voltage level required to fulfill the power demand. One possible approach to achieve a high charging power is increasing the battery voltage, i.e., increase the voltage level from 400 V to 800 V. This publication discusses the main aspects of charging by incorporating all high-voltage components in the vehicle. An increase of the voltage level and charging power affect all high-voltage components. The thermal management of the battery has to be considered. High-voltage vehicle architecture design considerations are discussed including thermal-management and battery-design aspects. Different charging characteristics from electric vehicles (EVs) available, are compared with an estimated fast charging profile which is based on theoretical background of available cells including consideration of physical and…
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A New Approach of Generating Travel Demands for Smart Transportation Systems Modeling

Ford Motor Company-Zhen Jiang, Chen Liang, Cassandra Telenko, Bo Wang, Yan Fu
Purdue University-Ruoxi Wen, Hua Cai
  • Technical Paper
  • 2020-01-1047
To be published on 2020-04-14 by SAE International in United States
The transportation sector is facing three revolutions: shared mobility, electrification, and autonomous driving. To inform decision making and guide smart transportation system development at the city-level, it is critical to model and evaluate how travelers will behave in these systems. Two key components in such models are (1) individual travel demands with high spatial and temporal resolutions, and (2) travelers’ sociodemographic information and trip purposes. These components impact one’s acceptance of autonomous vehicles, adoption of electric vehicles, and participation in shared mobility. Existing methods of travel demand generation either lack travelers’ demographic information and trip purposes, or only generate trips at a zonal level. Higher resolution demand and sociodemographic data can enable analysis of trips’ shareability for car sharing and ride pooling and evaluation of electric vehicles’ charging needs. To address this data gap, we propose a new approach of travel demand generation based on households. Census data provide the demographic information for each household (e.g., the number of adults and kids, income and education level, vehicle ownership etc.). The travel demands of each individual…
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Starting Process Control of a 2-Cylinder PFI Gasoline Engine for Range Extender

Tongji University-Minglong Li, Ran Zhang, Xingyu Zeng, Weiqi Ding, Weiang Mao, Shaoye Jin, Rufeng Xu, Dengke Yuan, Zongjie Hu, Zaimin Zhong, Liguang Li
  • Technical Paper
  • 2020-01-0315
To be published on 2020-04-14 by SAE International in United States
With the increasing worldwide concern on environmental pollution, battery electrical vehicles (BEV) have attracted a lot attention. However, it still couldn’t satisfy the market requirements because of the low battery power density, high cost and long charging time. The range-extended electrical vehicle (REEV) got more attention because it could avoid the mileage anxiety of the BEVs with lower cost and potentially higher efficiency. When internal combustion engine (ICE) works as the power source of range extender (RE) for REEV, its NVH, emissions in starting process need to be optimized.In this paper, a 2-cylinder PFI gasoline engine and a permanent magnet synchronous motor (PMSM) are coaxially connected. Meanwhile, batteries and load systems were equipped. The RE co-control system was developed based on Compact RIO (Compact Reconfigurable IO), Labview and motor control unit (MCU). Focused on the starting process, the effects of first firing speeds, throttle control strategies and coolant temperatures were tested.The results show that the higher first firing speed is preferred without obvious torque fluctuation, and longer throttle switching duration to high load results in…
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Development of the Rig and Hardware-in-the-Loop Test Bench for Evaluating Steering Performance

Hyundai Motor Company-Changsu Kim, Byungrim Lee, Youngdae Park
  • Technical Paper
  • 2020-01-0647
To be published on 2020-04-14 by SAE International in United States
The development of vehicles faces changes in many future flows. The vehicle’s power transfer systems are being changed from conventional types to Hybrid, Electric and Hydrogen vehicles. At this moment, the technology of EPS (Electric Power Steering) system has been expanding from a simple torque assist system to LKAS(Lane Keeping Assist System), PAP(Park Assist Pilot), ALCAS(Active Lane Change System), ADAS(Advanced Driver Assistance System). A good test bench is necessary for the evaluation of both hardware and control logics of EPS in these complexities of development process. Simultaneous Rig and HILS tests can be performed to check that the steering hardware system can perform to the concept of the development vehicle and develop EPS control logic performances. The hardware performance of the steering system might be evaluated based on measured friction and stiffness, taking into account various driving conditions. And the control logic of the EPS can be evaluated based on the response capability and steering torque measured through the appropriate vehicle model which could represent virtual driving conditions.
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Parameter Determination for the Battery Equivalent Circuit Model Using a Numerical Integro-Differential Method

AVL GmbH-Chao Chen
  • Technical Paper
  • 2020-01-1179
To be published on 2020-04-14 by SAE International in United States
The battery equivalent circuit model consisting of an open circuit voltage (OCV) source and a resistor in series with parallel resistor-capacitor (RC) elements is widely used in system-level simulation. The accuracy of the transient I-V characteristics of the battery model strongly relies on the values of the RC parameters prescribed in the circuit. One of the solutions for determining RC parameters is curve-fitting the measurement data of the battery voltage in the relaxation period obtained from a charge or discharge current pulse test. Since the equation used for curve-fitting can be expressed as the sum of multiple exponential functions which are nonlinear with respect to the RC parameters, the nonlinear least-square (LS) algorithm shows poor performance or even fails due to its sensitiveness to initial guesses of the solutions.One approach that makes use of the unique feature of the sum of two exponentials reformulates the nonlinear voltage equation to a linear one and calculates out the RC parameters using the linear LS algorithm. However, the approach cannot be applied to the model with more than…
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A Method of the Improvement of Wireless Power Transfer (WPT) System Efficiency, Compatibility, EMI Reduction, and Foreign Object Detection (FOD) for EV Applications

Hyundai Motor Co.-JaeEun Cha, Woo Young Lee, Gyu-Yeong Choe, Young Jin Kim, Jung Hong Joo, Jin Hwan Jung
  • Technical Paper
  • 2020-01-0530
To be published on 2020-04-14 by SAE International in United States
During the charging Electric Vehicle (EV), power transfer occurs in the power electronics of an EV powertrain. Understanding how the Wireless Power Transfer (WPT) occurs would be beneficial for achieving convenient charging method. This paper focuses on improving WPT system pad compatibility, power transfer efficiency, EMI reduction, and Foreign Object Detection (FOD). The choice of convertible WPT pad for circular and DD type coil, improvement of pad compatibility is analyzed in this paper. In addition, several control methods of increasing WPT system efficiency are proposed. Firstly, the effect of Full Bridge - Half Bridge (FB-HB) is introduced, and the influence of a Bridgeless control scheme is discussed. A new, ferrite pad structure is applied to WPT system in order to achieve EMI reduction. Lastly, a new strategy of Foreign Object Detection (FOD) is suggested for WPT system using phase difference and frequency variation detection.
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Optimal Management of Charge and Discharge of Electric Vehicles Based on CAN Bus Communication

Suizhou-WUT Industry Research Institute-Gangfeng Tan
Wuhan University of Technology-Haoyu Wang, Donghua Guo, Zhenyu Wang, Hanyu Zhang, Zhicheng Hu
  • Technical Paper
  • 2020-01-1297
To be published on 2020-04-14 by SAE International in United States
With the shortage of energy and the continuous development of automotive technology, electric vehicles are gradually gaining popularity. However, during the running of the electric vehicle, there is a risk of exhaustion of the electric power, and the position of the charging pile is fixed, which is likely to cause anxiety and worry of the owner. At present, there is a lack of an effective energy consumption prediction system, which is convenient for the driver to make reasonable driving planning guidance. As a standard serial communication protocol of ISO, CAN bus has a simple structure, short development cycle, stability and reliability. In this paper, the CAN bus is used to extract the dynamic parameter information of the speed, engine speed and throttle opening of the traveling vehicle in real time. At the same time, based on the GPS and cloud database, the road condition information of the expected driving section is comprehensively considered, and the real-time energy consumption prediction model of the electric vehicle is established. The predicted value is compared with the remaining electricity,…
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Comparison of EVSE Charge Management Systems for Limited Electrical Infrastructure

Sacramento Municipal Utility District-Dwight MacCurdy, Carol D. Kay, Karun Kumar, Deepak J. Aswani
  • Technical Paper
  • 2020-01-0532
To be published on 2020-04-14 by SAE International in United States
The installed cost of EV charging stations can vary widely depending on site specific conditions and the number and type of EV charging stations (EVSE) to be installed. The cost can exceed $10,000 per EVSE if panel or switch gear upgrades are needed or if trenching is required. These infrastructure costs can pose a significant barrier to EV adoption for fleet operators or for employers who wish to provide EV charging for employees. Smart EVSE can play a role in managing the infrastructure and installation cost of EVSE. Such products can enable charging when there are limitations in electrical capacity. Three types of smart EVSE are tested and compared: 1) fully autonomous/local control, 2) networked/cloud managed control, and 3) a hybrid of local and cloud managed control.