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Research on Factors to Influence Coasting Resistance for Electric Vehicles

Changan Mazda Auto Company-Yong Ren
Chongqing Changan New Energy Auto Co., Ltd.-Guan Gong, Chen Zhao, Xiaohang Zhou, Chenghao Deng, Cheng Yu, Fuyong Yu, Anjian Zhou
  • Technical Paper
  • 2020-01-1068
To be published on 2020-04-14 by SAE International in United States
The research on coasting resistance is vital to electric vehicles, since the smaller the coasting resistance, the longer the coast-down distance. Vehicle resistance consists of rolling resistance, vehicle inner resistance and the aerodynamic drag. The vehicle inner resistance is mainly caused by driveline’s friction loss and oil splash loss. The rolling resistance is decided by tire resistance coefficient, which is influenced by tires and road conditions. And the aerodynamic drag is affected by vehicle’s shape and air. In this paper, four factors that are tire pressure, road surface condition, air circulating mode, and atmosphere temperature are examined. Experimental tests have been conducted on three different vehicles: one subcompact sedan, one compact sedan and one compact SUV. The outcome shows that, when the tire pressure is 20% less, the average coasting resistance is increased by 1% to 3% depending on vehicle types, which indicates an increase in energy consumption by 0.9% to 2.4%. On wet road surface, the average coasting resistance is increased by 10% - 20%, which could decrease the NEDC range by 6% to…
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Comparison of Different Methods for Panel Dent Resistance using Numerical Assessment and Influence of Materials used in Automotive Industry

Tata Technologies Ltd.-Ashish Sathaye, Deepak Srivastava, Manivasagam Shanmugam
  • Technical Paper
  • 2020-01-0483
To be published on 2020-04-14 by SAE International in United States
Traditionally, the automotive outer panels, giving vehicle its shape, have been manufactured from steel sheets. The outer panels are subjected to loads due to wind loading, palm-prints, person leaning on the vehicle, cart hits, and hail stones for example. Consumer awareness about these two panel characteristics: Oilcanning and Dent resistance, has been increased through recent marketing studies. Apart from perceptive quality, another factor depending on the dent performance is insurance and respective cost implications. Dents can occur due to several reasons such as object hits, parking misjudgment, hail stones etc. Phenomenon can be divided in two types, static and dynamic denting. Static dent case covers scenario wherein interaction with outer panel is mostly quasi-static. Hail stones presents dynamic case where object hits a panel with certain kinetic energy. Automotive companies usually perform static dent assessment to cover all the cases. In this paper, scope is to discuss the comparison between two methods and its results using Finite Element Analysis. Influence of panel stiffness on dent resistance is also studied. Panel dent resistance depends on different…
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A Method for Simultaneous State of Charge, Maximum Capacity and Resistance Estimation of a Li-Ion Cell Based on Equivalent Circuit Model

Auburn University-Saurabh Gairola, Yang Hu
  • Technical Paper
  • 2020-01-1182
To be published on 2020-04-14 by SAE International in United States
Accurate estimation of the State of Charge (SOC), maximum capacity (Qmax) and internal resistance are critical for battery monitoring, i.e., determining the status, health, and performance figures of a battery. SOC is a key indicator of the instant status for battery systems, while Qmax and internal resistance are related to the capacity fade (SOHQ) and power fade (SOHP) respectively, which represent the abilities of a battery to store energy, retain charge over extended periods and provide the required power for acceleration, etc. Traditional methods using complex models and look-up tables have high computation requirements which makes them unsuitable for online applications. In this paper, we propose a simple method for simultaneous SOC, Qmax and internal resistance estimation based on a second-order equivalent circuit model (ECM). A Variable Model framework based Adaptive Extended Kalman filter (VM-AEKF) is implemented for joint SOC and model parameter estimation where the VM framework is designed specifically to improve the stability and accuracy of parameter estimation under conditions when the system is not sufficiently excited by the input signal. Simultaneously, a…
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Combustion Enhancement in a Gas Engine Using Low Temperature Plasma

Chiba University-Yasuo Moriyoshi, Tatsuya Kuboyama
Oita University-Kimitoshi Tanoue
  • Technical Paper
  • 2020-01-0823
To be published on 2020-04-14 by SAE International in United States
Low temperature plasma ignition has been proposed as a new ignition technique as it has features of good wear resistance, low energy release and combustion enhancement. In the authors’ previous study, lean burn limit could be extended by low temperature plasma ignition while a voltage drop during discharge, leading to the transition to arc discharge, was found. In this study, the structure of plug and power supply’s performance with steep voltage rising with time, dV/dt, are examined to investigate the effects on combustion performance. As a result, the following conclusions were deduced. (1) The lean combustion limit was extended when a four-pole plug with IES power source was used due to volumetric ignition. (2) A modified one-pole plug to improve the electric insulation, leading to prevent the voltage drop, could not extend the lean limit due to less volumetric ignitability. The specifications of plug must be improved to expand the ignition volume. (3) Using a variable dV/dt power source, the effect of dV/dt was tested. The combustion characteristics were not affected by dV/dt in this…
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Sensitivity Analysis of Aerodynamic Drag Coefficient to EPA Coastdown Ambient Condition Variation

FCA US LLC-Todd Lounsberry, John Tripp, Gregory Fadler
  • Technical Paper
  • 2020-01-0666
To be published on 2020-04-14 by SAE International in United States
The test cycle average drag coefficient is examined for the variation of allowable EPA coastdown ambient conditions. Coastdown tests are ideally performed with zero wind and at SAE standard conditions. However, often there is some variability in actual ambient weather conditions during testing, and the range of acceptable conditions is further examined in detail as it pertains to the effect on aerodynamic drag derived from the coastdown data. In order to “box” the conditions acceptable during a coastdown test, a sensitivity analysis was performed for wind averaged drag ((CDW ) ̅) as well as test cycle averaged drag coefficients (CDWC) for the fuel economy test cycles. Test cycle average drag for average wind speeds up to 16 km/h and temperatures ranging from 5C to 35C, along with variation of barometric pressure and relative humidity are calculated. The significant effect of ambient cross winds on coastdown determined drag coefficient is demonstrated.
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Optimization of the Aerodynamic Lift and Drag of LYNK&CO 03+ with Simulation and Wind Tunnel Test

Dassault Systemes(Shanghai) Information Technology Co.-Weiliang Xie, Bo Li, Xiaowei Zhao
Geely Automobile Research Institute-Qian Feng, Biaoneng Luo, Huixiang Zhang, Hong Peng, Zhenying Zhu, Zhi Ding, Ling Zhu
  • Technical Paper
  • 2020-01-0672
To be published on 2020-04-14 by SAE International in United States
Based on the first sedan of the LYNK&CO brand from Geely, a high performance configuration with the additional aerodynamic package was developed. The aerodynamic package including the front wheel deflector, the front lip, the side skirt, the rear spoiler and the rear diffuser, were upgraded to generate enough aerodynamic downforce for better handing stability, without too much compromising of the aerodynamic drag of the vehicle to keep a low fuel consumption. Simulation approach with PowerFLOW, combined with the design space exploration method were used to optimize both of the aerodynamic lift and drag. Wind tunnel test was also used to firstly calibrate the simulation results and finally to validate the optimized design. The results turn out to be appropriate trade-off between the lift and the drag to meet the aerodynamics requirement, and a consistently good matching between the simulation and test.
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Characterization of Seat Lateral Support as a Mechanical Behavior

General Motors LLC-Bonita Thomas
OBannon Technologies-Terry O'Bannon
  • Technical Paper
  • 2020-01-0870
To be published on 2020-04-14 by SAE International in United States
Seat lateral support is often talked about as a design parameter, but usually in terms of psychological perception. There are many difficulties in quantifying lateral support mechanically to the engineering teams: Anthropometric variation causes different people to interact with the seat in different places and at different angles, BPD studies are usually planar and don’t distinguish between horizontal support and vertical resistance to sinking in, most mechanical test systems are typically single-DOF and can’t apply vertical and horizontal loads concurrently, and there is scant literature describing the actual lateral loads occupants. In this study, we characterize the actual lateral loading on example seating (both driver and passenger, as passenger experience will become more important as autonomous vehicles evolve) from various sized/ shaped occupants according to dynamic pressure distribution. From this information, a six-DOF load and position control test robot (KUKA OccuBot) is used to replicate that pressure distribution. The effect of various sizes and shapes of indenters is explored. In the spirit of the appendix of SAE standard J2896, we suggest some standard mechanical test…
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Analysis of Various Vehicle Dynamic Simulations Software Packages Using Design of Experiments (DOE)

Engineering Systems Inc.-R. Matthew Brach, Emmanuel Jay Manuel, Robert Bailey, Joshua Rogers, Shawn P. Capser
  • Technical Paper
  • 2020-01-0639
To be published on 2020-04-14 by SAE International in United States
A previous paper on this topic presented the use of design of experiments (DOE) to evaluate the sensitivity of vehicle dynamics simulation of the postimpact motion of a vehicle that included high initial rotational rates. That investigation involved only one software package and thus was confined to one simulation model for the purposes of developing and refining the analysis method rather than including a variety of simulation models for broader application. This paper expands the application of the method to investigate the comparative behavior and sensitivity of several other vehicle dynamic simulation models commonly used in the field of crash reconstruction. The software packages included in the studies presented in this paper are HVE (Simon and EDSMAC4), PC-Crash and VCRware. This paper will present the results of the study, conducted using DOE, using these models. The eleven factors selected for the study presented here were chosen based largely on the results of the prior study. The experimental design was expanded from 16 trials to 32 trials to provide additional insight into the interactions between the…
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Scenario Analysis and Control Comparison for a High Speed Autonomous Vehicle

University of California, Irvine-Vatche Donikian, Joseph Bell, Gregory Washington
  • Technical Paper
  • 2020-01-0710
To be published on 2020-04-14 by SAE International in United States
This paper studies the simulation and control of an autonomous dragster. Four scenarios are provided that are critical to vehicle and driver safety in drag racing. Equations are then created to model the behavior during these safety scenarios. The use of a kinematic bicycle model and a Newtonian wheel stand model are discussed for plane-of-motion and out-of-plane vehicle movement, respectively. A separate controller is designed for each model by comparing different control methods. Proportional-Integral-Derivative (PID) control, optimal control, and model predictive control (MPC) are presented and applied to the models. The models are simulated from a speed of 75 m/s, being the estimated top speed of the research vehicle, up to a top speed of 150.5 m/s which is in alignment with the highest recorded speed of a dragster. The comparison of the control techniques yields MPC as superior for the bicycle model and PID as sufficient for the wheel stand model. Latency of the system is also discussed and accounted for in the system.
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Volume of Fluid vs. Cavitation CFD-Models to Calculate Drag Torque in Multi-Plate Clutches

SIMERICS GmbH-Rudi Niedenthal
Technical University of Munich-Daniel Groetsch, Katharina Voelkel, Hermann Pflaum, Karsten Stahl
  • Technical Paper
  • 2020-01-0495
To be published on 2020-04-14 by SAE International in United States
Wet running multi-plate clutches and brakes are important components of modern powershift gearboxes and industrial powertrains. In the open stage, drag losses occur due to fluid shear. Identification of drag losses is possible by experiment or CFD-simulation. For calculation of the complex fluid flow of an open clutch CFD-approaches such as the Volume of Fluid (VoF) method or the Singhal cavitation model are applicable. Every method has its own specific characteristics. This contribution sets up CFD-calculation models for different clutches with diverse groove designs. We present results of calculations in various operating conditions obtained from the Singhal cavitation model and the VoF-method. Despite the high spatial resolution of the calculation models the usage of a modern commercial CFD-solver and mesher (Simerics MP+) results in very short calculation times. The developed CFD-models consider the geometry of a complete clearance consisting of the friction plate, the gap between the plates, the steel plate and the flow conditions arising from the design of the inner and outer plate carrier. The full 360-degree modeling makes it possible to take…