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The journal Automotive Innovation is sponsored by China SAE, published through Springer, distributed around the world, and reflects the top-level research and technical advance of automotive engineering. Automotive Innovation newsletter in July includes the following contents： 1. Article Recommendation——Three papers on electric vehicles 2. China SAE News: · ISC 2021 was successfully held in Changchun |
  
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State of Charge Estimation for Lithium-Ion Battery Based on Improved Cubature Kalman Filter Algorithm Guochun Li, Chang Liu, Enlong Wang & Limei Wang |
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| An improved cubature Kalman filter (CKF) algorithm for estimating the state of charge of lithium-ion batteries is proposed. This improved algorithm implements the diagonalization decomposition of the covariance matrix and a strong tracking filter. First, a first-order RC equivalent circuit model is first established and verified, whose voltage estimation error is within 1.5%; this confirms that the model can be used to describe the characteristics of a battery. Then the calculation processes of the traditional and proposed CKF algorithms are compared. Subsequently, the improved CKF algorithm is applied to the state of charge estimation under the constant-current discharge and dynamic stress test conditions. The average errors for these two conditions are 0.76% and 1.2%, respectively, and the maximum absolute error is only 3.25%. The results indicate that the proposed method has higher filter stability and estimation accuracy than the extended Kalman filter (EKF), unscented Kalman filter (UKF) and traditional CKF algorithms. Finally, the convergence rates of the above four algorithms are compared, among which the proposed algorithm track the referenced values at the highest speed. | |||
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Keywords: Lithium-ion battery · State of charge · Cubature Kalman filter · Strong tracking filter · Covariance matrix diagonalization decomposition Li, G., Liu, C., Wang, E. et al.: State of charge estimation for lithium-ion battery based on improved cubature Kalman Filter Algorithm. Automotive Innovation (2021) |
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Critical Speeds of Electric Vehicles for Regenerative Braking Xianxu Bai, Gen Chen, Weihan Li, Rui Jia, Liang Xuan, Anding Zhu & Jingchang Wang |
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| Efficient regenerative braking of electric vehicles (EVs) can enhance the efficiency of an energy storage system (ESS) and reduce the system cost. To ensure swift braking energy recovery, it is paramount to know the upper limit of the regenerative energy during braking. Therefore, this paper, based on 14 typical urban driving cycles, proposes the concept and principle of confidence interval of “probability event” and “likelihood energy” proportion of braking. The critical speeds of EVs for braking energy recovery are defined and studied through case studies. First, high-probability critical braking speed and high-energy critical braking speed are obtained, compared, and analyzed, according to statistical analysis and calculations of the braking randomness and likelihood energy in the urban driving cycles of EVs. Subsequently, a new optimized ESS concept is proposed under the frame of a battery/ultra-capacitor (UC) hybrid energy storage system (HESS) combined with two critical speeds. The battery/UC HESS with 9 UCs can achieve better regenerative braking performances and discharging performances, which indicates that a minimal amount of UCs can be used as auxiliary power source to optimize the ESS. After that, the efficiency regenerative braking model, including the longitudinal dynamics, motor, drivetrain, tire, and wheel slip models, is established. Finally, parameters optimization and performance verification of the optimized HESS are implemented and analyzed using a specific EV. Research results emphasize the significance of the critical speeds of EVs for regenerative braking. | |||
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Keywords: Electric vehicle · Regenerative braking · Critical speed · Hybrid energy storage system
Driving cycle · Confidence interval
Bai, X. X., Chen, G., Li, W. H., et al.: Critical speeds of electric vehicles for regenerative braking. Automotive Innovation (2021) |
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Study of longitudinal–vertical dynamics for in-wheel motor-driven electric vehicles Yechen Qin, Ze Zhao, Zhenfeng Wang & Guofa Li |
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| The in-wheel motor (IWM)-driven electric vehicles (EVs) attract increasing attention due to their advantages in dimensions and controllability. The majority of the current studies on IWM are carried out with the assumption of an ideal actuator, in which the coupling effects between the non-ideal IWM and vehicle are ignored. This paper uses the braking process as an example to investigate the longitudinal–vertical dynamics of IWM-driven EVs while considering the mechanical–electrical coupling effect. First, a nonlinear switched reluctance motor model is developed, and the unbalanced electric magnetic force (UEMF) induced by static and dynamic mixed eccentricity is analyzed. Then, the UEMF is decomposed into longitudinal and vertical directions and included in the longitudinal–vertical vehicle dynamics. The coupling dynamics are demonstrated under different vehicle braking scenarios; numerical simulations are carried out for various road grades, road friction, and vehicle velocities. A novel dynamics vibration absorbing system is adopted to improve the vehicle dynamics. Finally, the simulation results show that vehicle vertical dynamic performance is enhanced. | |||
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Keywords: Mechanical–electrical coupling · Longitudinal–vertical dynamics · In-wheel motor · Suspension system Qin, Y., Zhao, Z., Wang, Z. et al.: Study of longitudinal–vertical dynamics for in-wheel motor-driven electric vehicles. Automotive Innovation (2021) |
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| ISC 2021 was successfully held in Changchun | |||
 The 3rd annual FISITA Intelligent Safety Conference (ISC 2021) took place on 16 July 2021 in Changchun, China, organized by China SAE and FISITA. This event delivered a high-quality, international speaker line-up, which considers and discusses the important topics of the safety of future mobility, including SOTIF, Cybersecurity, Impacts of Human Factors on Safety. There were over 600 physical attendees and over 40,000 online views. The conference invited distinguished experts to present state-of-the-art technologies, please click here for further information. |
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| WNEVC 2021 will be held on Sept. 15- 17 at Haikou | |||
 The 3rd World New Vehicle Congress (WNEVC 2021) will be held on Sept. 15-17, 2021 at Haikou. WNEVC is hosted by China Association for Science and Technology (CAST), the People's Government of Hainan Province, and state ministries of China, and organized by China SAE. This year's event will continue to share insights, discuss cutting-edge trends, and build a high-end international exchange platform in the field of global new energy vehicles. There will be 100+ speakers, 2000+ delegates, and 10000 ㎡ exhibition. The preliminary agenda is now available, please click here for further information. |
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| SAECCE will be held on Oct. 19-21 at Shanghai | |||
 SAECCE 2021 will be held at Shanghai Automotive Convention and Exhibition Center on October 19-21. With the theme of "Automobile Plus, Collaborative Innovation", SAECCE 2021 will focus on Electrification, Intelligence, Connected and Sharing, deeply discuss on how to quickly promote technological innovation and reshape the new industrial structure. There will be 500+ technical reports, 3000+ delegates and 100+ exhibitors. For more information, please click here. |
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Automotive Innovation Sponsored by China SAE and published globally via Springer Nature, Automotive Innovation aims to be a world-class journal that provides abundant sources of innovative findings for automotive engineers and scientists. The journal is published quarterly, ensuring high-quality papers satisfying international standards. With the editorial board consisting of world-renowned experts, it has attracted readers from 72 countries and regions. The highest download of a single article wins more than 17,000. The journal provides a forum for the research of principles, methodologies, designs, theoretical background, and cutting-edge technologies in connection with the development of vehicle and mobility. The main topics cover: energy-saving, electrification, intelligent and connected, safety, and emerging vehicle technologies. Editors-in-Chief Jun Li, Academician of CAE, President of China SAE, Professor of Tsinghua University Frank Zhao, President (2018-2020) of FISITA, President of Tsinghua Automotive Strategy Research Institute Executive Editor-in-Chief Prof. Mike Ma，Executive Chief Editor of Automotive Innovation, Professor of Jilin University, VP Technical FISITA |
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Paper submission and browse www.ChinaSAEJournal.com.cn www.springer.com/42154 Contacts: Ms. Lily Lu Tel: +86-10-50950101 Email: jai@sae-china.org |
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