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Analysis of a Coordinated Engine-Start Control Strategy for P2 Hybrid Electric Vehicle

Tianjin University-Chen Zhao, Bingfeng Zu, Yuliang Xu, Zhen Wang, Lina Liu, Jianwei Zhou
Weichai Power Co Ltd-Guangxing Zhao
Published 2019-11-04 by SAE International in United States
P2 hybrid electric vehicle is the single-motor parallel configuration integrating with an engine disconnect clutch (EDC) between the engine and the motor. The key point with P2 hybrid electric vehicle is to start the engine utilizing the single driving motor while still propelling the vehicle, which requires an appropriate engine-start control strategy and a high mechanical performance of EDC. Since the space for EDC is limited, EDC torque response is difficult to follow the torque command, which complicates the issue of precisely controlling the clutch. Consequently, methods proposed in massive papers are inappropriate for current EDC of target vehicle. Considering that slip control of shifting clutch also contributes to reducing impact of engine start assisted by EDC, a detailed engine-start control strategy was proposed to simplify the control of EDC for being applied to actual target vehicle. Furthermore, the control strategy proposed in this paper was utilized to realize driving mode transformation from motor-only to engine-only. In this paper, a detailed hybrid electric vehicle simulation model was established with the consideration of dynamic characteristics of…
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Security Mechanism and Verification of Vehicle Network Based on Message Authentication

Nanjing University of Science and Technology-Benxiong Wang, Dawei Pi, Boyuan Xie, Hongliang Wang, Xianhui Wang
Published 2019-11-04 by SAE International in United States
In view of the relatively bare network environment of the current car controller area network (CAN) and the high-performance requirements of most existing security mechanisms for electronic control units (ECUs), based on a new and faster network transmission protocol, a lightweight car bus authentication method using Message Authentication Code (MAC) is proposed. In this case, the vehicle network is modularized in dependence on the different functional requirements of each part of the bus, calculation tasks are processed by the gateway of the corresponding network segment, the confidentiality and correctness of the vehicle network can be guaranteed by synchronizing the message authentication tables in all nodes, and the transmission rate gets obvious improvement under CAN FD (flexible data-rate) protocol as well. In this paper, the security and real-time performance of the vehicle network are verified by hardware experiments, and the impact of the encryption method on the performance in the network is verified by software simulation. The CAN FD bus is formally designed in the MATLAB environment with finite state machine. The state machine model can…
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Proton Exchange Membrane Fuel Cell Fault Rapid Diagnosis Method Based on Electrochemical Impedance Spectroscopy and Fuzzy C-Means Algorithm

Tongji University-Su Zhou, Shoujian Zheng, Zhe Hu
Published 2019-11-04 by SAE International in United States
Water management is a key research direction for the performance and lifetime of proton exchange membrane fuel cell (PEMFC) stacks. The paper is aimed to develop an online fault diagnosis method that distinguishes different degrees of flooding and drying within a fuel cell stack by unobservable variables. In our research, the equivalent circuit model is established and electrochemical impedance spectroscopy (EIS) is utilized. The mathematical methods are used to extract the fault features. Fuzzy C-means is used to classify the selected features and the diagnostic rules are automatically extracted from the data. Through verification, the interpretability and computational efficiency of the proposed method are achieved.
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Axle Torque Distribution to Improve Vehicle Handling and Stability

First Automobile Works Group Corporation Research and Develo-Aibin Wu, Chao Li, Yongqiang Zhao, Jinlong Cui
Published 2019-11-04 by SAE International in United States
The majority of the fully electric vehicles currently on the market have a basic drivetrain configuration, consisting of multiple electric motors, which promise considerable performance enhancements in terms of vehicle behavior and active safety. A significant advantage was achieving measurable benefits in terms of vehicle cornering response through controlling the individual drivetrains. This paper presents an axle torque distribution method to improve a 4WD vehicle steering performance. The method can automatically adjust the output drive torque of the front and rear motors of the vehicle to change the vehicle yaw rate before ESP intervention, and at the same time remain the driver torque demand unchanged. In this paper we present a feedback yaw rate controller. When the estimated yaw rate differs from the actual yaw rate with a pre-defined small threshold, a yaw rate control is active, the purpose of the controller is to reduce the vehicle understeer characteristic. The simulation and experimental test results shows that this proposed method can reduce the vehicle understeer characteristic and improve the vehicle handling and stability performance.
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Cooperative Distribution Strategy of Regenerative Braking and Pneumatic Braking of an Electric Commercial Vehicle

Nanjing University of Science and Technology-Qing Cheng, Dawei Pi, Boyuan Xie, Hongliang Wang, Xianhui Wang
Published 2019-11-04 by SAE International in United States
This paper mainly proposes one type control strategy of the regenerative braking system of an electric commercial vehicle under normal braking condition. With the main goal of recovering as much energy as possible, the braking force distribution strategy based on maximum regenerative braking optimization is studied under the restriction of ECE regulation and state of charge (SOC) of battery. Firstly, the related models of the regenerative braking system and the target vehicle are separately established in MATLAB/Simulink. Then, the distribution strategy of braking force is developed and optimized considering the influence of SOC and vehicle speed respectively. Finally, the braking effects of this control strategy in the typical deceleration process are numerical simulated and analyzed. Simulation results depict that this control strategy can recover more braking energy under the premise of ensuring braking safety and great braking performance compared with the common braking strategies with traditional strategy and without regenerative braking.
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Parameter Identification for One-Dimension Fuel Cell Model Using GA-PSO Algorithm

Tongji University-Mingzhi Shao, Huili Wei, Sichuan Xu
Published 2019-11-04 by SAE International in United States
When studying on how to identify the proton exchange membrane fuel cell model parameters accurately and quickly, the model frequently used is a lumped parameter model. Compared to this kind of model, one-dimensional dynamic proton exchange membrane fuel cell model can correlate the physical parameters with output characteristics of fuel cell to predict the effects of design parameters, materials and environmental conditions, thus reducing the need for experimentation. However, there is little literature about parameter identification for one-dimensional dynamic models currently. In this paper, a one-dimension dynamic proton exchange membrane fuel cell model with many assumptions for reducing the complexity of calculation is realized in Matlab-Simulink environment. The model consists of five interacting subsystems. The GA-PSO hybrid optimization algorithm is used to identify the parameters of fuel cell model to emulate the output characteristics of different proton exchange membrane fuel cells. This hybrid algorithm is an improved Particle Swarm Optimization Algorithm relying on Genetic Algorithm's strong global search ability, with the aim of maintaining the population diversity and avoiding premature convergence. The result shows that…
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Research on the EMF Impact of Vehicles on Human Health

CATARC-Li Jiang, Xu Zhang, Shurong Cai, Kaiyi Sun, Chen Guo
Published 2019-11-04 by SAE International in United States
In recent years, with the rapid development of new energy vehicles, the impact of electromagnetic field (EMF) from vehicles to human body has become a growing concern of consumers. The national standard GB/T 37130-2018 "Measurement methods for electromagnetic field of vehicle with regard to human exposure" was officially released at the end of 2018, which was attracted extensive attention of vehicle manufacturers, testing structures and consumers. GB/T 37130-2018 specifies the test methods for low frequency EMF of vehicles. In this paper, a comparison of the main technical contents between GB/T 37130-2018 standard and International electro technical commission (IEC) standard, Japanese automotive standard organization (JASO) and other relevant standards is present; and then a general survey based on the test method specified in GB/T 37130 standard is carried out by comparing the test results of multiple vehicle models, which can give the reader an intuitive understanding of the EMF level of vehicle.
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Study on Comprehensive Evaluation Index of Front Collision Hazard of Intelligent Vehicle

Beihang University-Deng Weiwen
Jilin Normal University-Sumin Zhang
Published 2019-11-04 by SAE International in United States
Collision avoidance technology is one of the key areas in the longitudinal safety research of intelligent vehicles. For the research of collision avoidance system, the existing methods usually use the evaluation index based on time interval or braking process to carry out risk assessment. In order to overcome the shortcomings of the formulas for describing the longitudinal hazard degree established in most studies, such as great differences, inconsistent standards and weak normalization, a comprehensive evaluation method for the longitudinal hazard in front-impact scenarios is established. This method takes into account both the analysis of time interval and braking process, and considers the non-linear variation of the longitudinal hazard degree with the real-time distance and speed of two vehicles. It can describe the longitudinal hazard degree of vehicles in dangerous traffic scenarios. Compared with the existing longitudinal hazard assessment methods, the effectiveness and universality of the pre-collision hazard assessment method proposed in this paper are demonstrated.
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In-Depth Analysis of Pedestrian-Vehicle Accidents Based on Chi-Square Test and Logistic Regression

CATARC-Xiaowei Lian, Xudong Li
Chang'an University-Jia Deng, Fujun Cui
Published 2019-11-04 by SAE International in United States
Taking the pedestrian-vehicle accidents in the China in-Depth Accident Study (CIDAS) database as a sample case, 13 accidents morphological parameters were selected from three aspects: human, vehicle and environmental factors, and their depth analysis was carried out to obtain their distribution law through the card. The chi-square test and logistic regression method are used to analyze the correlation between the injury severity of pedestrians and other accidental morphological parameters in pedestrian-vehicle accidents. The results show that there is no significant correlation between gender/season and injury severity of pedestrians. The age of pedestrians and the collision speed is the strongest correlation with injury severity of pedestrians. When a pedestrian is over 65 years old, the pedestrian height is in the range of 160-170cm, the collision speed is greater than 60 kilometers per hour, and the pedestrian speed is greater than 8 kilometers per hour, the probability of pedestrian injury is significantly increased.
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Composite Steering Strategy for 4WS-4WD EV Based on Low-Speed Steering Maneuverability

Tongji University-Yang Yang Wang, Zhi Guang Liu, Yuan Xing Jiang
Published 2019-11-04 by SAE International in United States
A composite steering control strategy, which combines four-wheel steering (4WS) and differential steering, is proposed in this paper, to optimize steering maneuverability in the conditions where the vehicle speed is below 15 Km/h, mainly for U-turning and parking conditions. A dynamic model is developed for the steering system and the tire system. Taking different steering wheel inputs into consideration, a 4WS control strategy proportional to the front wheel steering angle is quoted to improve the steering maneuverability in the low speed conditions and guarantee the manipulability by controlling the side slip of the vehicle. Based on the 4WS system, this paper explores the possibility of further improving the low-speed maneuverability of the vehicle through differential steering. And the differential steering control strategy is developed, including four hub-motor output modes. A composite steering controller is designed based on the 4WS-4WD electric vehicle platform. Through the real vehicle calibration tests, the output torque distribution coefficient of the hub motor in the differential steering control strategy is obtained, and the composite steering control strategy optimal for maneuverability is…
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