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• 2011, Vol. 2 No. 1
  Published on:15 January 2011 Previous issue    Next issue

  High pressure die casting process of magnesium alloys and its modeling and simulation for automobile industry (in Chinese)

  LIU Bai-Cheng, XIONG Shou-Mei

  2011, 2(1):  1-11.  doi:10.3969/j.issn.1674-8484.2011.01.001

  Abstract ( 2482 )   PDF (2834KB) ( 2349 )  

  Magnesium alloy is widely used in aerospace, automobile, and electronic industries and is referred to as the most promising green engineering material for the 21 century due to its lightweight, high specific strength and stiffness, good dumping performance and recyclability. Using magnesium alloy instead of steel or aluminum alloy in automobile industry is one of the effective ways to realize light weighting of automobiles to reduce fuel consumption and exhaust gas emission. High-pressure die casting process is the dominant manufacturing process for magnesium structural applications. The experimental study and modeling and simulation on high-pressure die casting process of magnesium alloys as well as development of vacuum die casting technology are important research directions for magnesium alloys. This paper highlights the research progress in experimental study on magnesium die casting process, development of vacuum die casting technology for magnesium alloys, modeling and simulation technologies for high pressure die casting process and their applications for process optimization.

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  Outlook of electric, hybrid and fuel cell vehicles

  CHEN Qing-Quan

  2011, 2(1):  12-24.  doi:10.3969/j.issn.1674-8484.2011.01.002

  Abstract ( 4829 )   PDF (1881KB) ( 2369 )  

  With the more stringent regulations on emissions and fuel economy the electric, hybrid and fuel cell vehicles have attracted more and more attentions by automakers, governments and customers. This paper reviews the state of the art of electric, hybrid and fuel cell vehicles with focus on their technical features and commercial road map. The fundamental features of electric, hybrid and fuel fell vehicles are summarized. The importance of using engineering philosophy as overall guidance for research & development is emphasized. The architecture and functionality of powertrains is distinctly analyzed. The challenge of energy management is explored, the function and interaction of global control and local is discussed, and the possible types of appropriate control model are suggested. As electric vehicle industry is a disruptive industry, a novel approach for commercialization is discussed. A comprehensive system approach should be adopted to achieve three goodness factors, namely good product, good infrastructure and good business model.

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  Trend of vehicle power technical development in China

  SU Wan-Hua

  2011, 2(1):  25-33.  doi:10.3969/j.issn.1674-8484.2011.01.003

  Abstract ( 2609 )   PDF (2331KB) ( 1987 )  

  Only the healfhy development of vehicle enterprises can realize the transition from manufacturing mode to innovative mode of China vehicle industry. Therefore, it is very important for China vehicle enterprises to struggle for the maximization of market value and scale, which requires the development of new technologies to meet the requirement both from customers and the vehicle-related legislations issued by the government. The development of vehicle technology must be acclimatized to the two requirements. In addition, the petroleum supply, the environment-friendship and the climate change are the important factors influencing vehicle technologies. A proposal for future development of vehicle technologies in China is put forward based on a review of advanced technologies worldwide.

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  Active stability control strategy based on maximum transmissible torque estimation

  YIN De-Jun, DA Qian-Xue, QING Shui-Hao, KU Yang-Yi

  2011, 2(1):  34-38.  doi:10.3969/j.issn.1674-8484.2011.01.004

  Abstract ( 3042 )   PDF (2807KB) ( 1549 )  

  The Direct Yaw Moment Control (DYC) is an effective way to enhance the two-dimensional motion stability of vehicles. A two-wheel vehicle model as a reference model was built to improve the performance and the practicality of two-dimensional motion control for electric vehicle in-wheel motors. The traction control was based on Maximum Transmissible Torque Estimation (MTTE) for constraining the slip effectively to increase the longitudinal friction force and lateral friction force, but also could provide some additional information on tire-road conditions. A new DYC topology was proposed based on MTTE for electric vehicles. The comparative numerical simulation of the whole control system between the normal DYC and the DYC enhanced by MTTE demonstrated the advantages of the proposed control strategy.

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  Supervisory control algorithm using GPS information for the parallel hybrid bus system

  Daeheung LEE, Jongyeo JEONG, Changwoo SHIN, Yeongil PARK, Wonsik LIM, Sukwon CHA

  2011, 2(1):  39-44.  doi:10.3969/j.issn.1674-8484.2011.01.005

  Abstract ( 2461 )   PDF (1380KB) ( 1384 )  

  A supervisory control strategy was developed to control the power distribution between an engine and an electric motor to make a bus transporting system more efficiently. The supervisory controller used the information like altitude, vehicle speed and set routes recorded from a GPS (global positioning system) receiver to optimize the fuel economy. The supervisory controller used Power Split Ratio (PSR) between two power sources. A PSR line derived from the Dynamic Programming theory can derive one of the optimal control concepts. The results show that the parallel hybrid bus can save its fuel consumption about 15%~40% compared with the conventional bus system.

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  Online fuel cell monitoring and operating conditions identification including life time measurement

  Erich Ramschak, Nicolas Fouquet, Harald Brandstaetter, Viktor Hacker

  2011, 2(1):  45-52.  doi:10.3969/j.issn.1674-8484.2011.01.006

  Abstract ( 2382 )   PDF (2984KB) ( 1623 )  

  An advanced version, AVL THDA, was developed to monitor the proton exchange membrane fuel cell (PEMFC) without using single cell voltage measurement (CVM) fault diagnosis and evaluate State of Health (SOH). The AVL THDA detects critical voltage drifts on cell level to ensure reliable operating conditions using harmonic distortion and electrical impedance spectroscopy. Detected critical operating conditions are assessed online and classified into membrane dry-out, liquid water droplets and low media supply issues. Thus, a system controller can immediately initiate counter measures preventing stack degradation. Taking into account long term effects in the fuel cell, also life time estimation is considered. The technology is capable of being fully integrated into existing fuel cell system components, therefore, has potential of cost efficient application.

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  Tests on electrical characteristics of polymer lithium-ion batteries

  ZHANG Yan-Qin, HU Bo, FENG Neng-Lian, ZHOU Da-Sen

  2011, 2(1):  53-57.  doi:10.3969/j.issn.1674-8484.2011.01.007

  Abstract ( 3029 )   PDF (1652KB) ( 1503 )  

  The electrical characteristics were analyzed using three experimental methods with a commercial 20-Ah polymer lithium-ion battery. The first method is a conventional test, in which the voltages are measured as the steady open-circuit voltages after 12-h rest at different state of charge. The second is the rapid test for measurement of open circuit voltages during the charge and discharge pulse with 1-min rest, with the third being the constant-current pulse test with 30-min rest for parameter identification based on the equivalent circuit model. The measurement results show that the constant-current pulse method with 30-minutes relaxation is effective to derive both the open-circuit voltage (OCV) curve and the electrical parameters.

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  Performance characteristics of LiFePO₄/graphite batteries for electric vehicles

  Cao-Hui, CHEN Xiao-Yu, HOU Min, ZHAO Wen-Peng, ZHANG Jian-Wen, WANG Dong

  2011, 2(1):  58-61.  doi:10.3969/j.issn.1674-8484.2011.01.008

  Abstract ( 2346 )   PDF (1997KB) ( 1344 )  

  Cells of 25 Ah with mass of 850 g were designed and tested with LiFePO4 (LFPO) as cathode material according to electrical vehicle demands. Discharges of different rates , cycles tests and abuse tests were adopted to certify that the cells have a discharge capacity of 26 Ah at 1 C rate and a high-rate capacity retention of 98% even at 6 C rate (150 A). The voltage at 50% SOC (state of charge) is about 3.0 V when discharged at 6 C rate. The capacity retention of 25-Ah cells is about 90% after 1 700 cycles. All the abuse tests on 25-Ah cells were carried out based on “Electrical Energy Storage System Abuse Test Manual for Electric and Hybrid Electric Vehicle Applications” suggested by U.S. Department of Energy FreedomCAR & Vehicle Technologies Program with satisfactory results. The 16-kWh EV battery units each assembled by 2 parallel, 102 series connections using these batteries have been delivered to Shanghai Automotive Industry Corporations.

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  Technologies to relief un-uniformity of power batteries used in electrical vehicles

  DAI Hai-Feng, SUN Ze-Chang, WEI Xue-Zhe, WANG Jia-Yuan

  2011, 2(1):  62-67.  doi:10.3969/j.issn.1674-8484.2011.01.009

  Abstract ( 3641 )   PDF (1312KB) ( 1846 )  

  The un-uniformity of power batteries used in electrical vehicles (EVs) shorten battery service life,reduce battery system performance,and limit battery packs application. To relief the growth of un-uniformity during battery application, the authors structured a battery management system (BMS) for designing single cell protection circuit,and proposed battery pack state estimation. The technologies to resolve the problem could be as a good thermal management in design stage, an efficient electric protection with cell voltage monitoring and cell balancing typically in using stage, and an appropriate cell classification in assembling stage.

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  Manufacture and performance tests of lithium iron phosphate batteries used as electric vehicle power

  ZHANG Guo-Qing, ZHANG Lei, RAO Zhong-Hao, LI Yong

  2011, 2(1):  68-71.  doi:10.3969/j.issn.1674-8484.2011.01.010

  Abstract ( 3418 )   PDF (2857KB) ( 2260 )  

  Owing to the outstanding electrochemical performance, the LiFePO4 power batteries could be used on electric vehicles and hybrid electric vehicles. A kind of LiFePO4 power batteries, Cylindrical 26650, was manufactured from commercialized LiFePO4, graphite and electrolyte. To get batteries with good high-current performance, the optimal content of conductive agent was studied and determined at 8% of mass fraction. The electrochemical properties of the batteries were investigated. The batteries had high discharging voltage platform and capacity even at high discharge current. When discharged at 30 C current, they could give out 91.1% of rated capacity. Moreover, they could be fast charged to 80% of rated capacity in ten minutes. The capacity retention rate after 2 000 cycles at 1 C current was 79.9%. Discharge tests at -20 ℃ and 45 ℃ also showed impressive performance. The battery voltage, resistance and capacity varied little after vibration test. Through the safety tests of nail, no inflammation or explosion occurred.

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  Development of a two-speed automatic transmission for pure electric vehicle

  HUANG Wei, WANG Yao, FENG Kun

  2011, 2(1):  72-76.  doi:10.3969/j.issn.1674-8484.2011.01.011

  Abstract ( 2458 )   PDF (2155KB) ( 3625 )  

  A two-speed automatic transmission used in electric sport utility vehicle was developed to improve the performance of the propulsion system of the vehicle. The motor active synchronization were researched using gear ratio choice principle and shift change control algorithm. Simulation results show that the two-speed automatic transmission reduces the maximum torque demand, the motor running speed and mechanical noise, and improves driveline efficiency. The bench tests show that the motor active synchronization control reduces the power interruption time, and helps the transmission achieve a high shifting quality.

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  Application of vibration signals in HCCI engines’ ignition timings identification (in Chinese)

  CHENG Yong, TANG Juan, HUANG Min-Li

  2011, 2(1):  77-84.  doi:10.3969/j.issn.1674-8484.2011.01.012

  Abstract ( 2097 )   PDF (2753KB) ( 2190 )  

  Engine ignition-timing is a basic combustion control feedback parameter, and is important for developing the homogeneous charge compression ignition (HCCI) combustion conditions. An ignition-timing identify method was proposed based on measuring vibration velocities and accelerations of the cylinder head using an engine block cylinder head’s finite element model and a vibration transmission system model. The vibration velocities and accelerations were measured on a 295 HCCI engine. The results show that there is a lag angle between the ignition timings determined by the vibration responses and determined by the rate of pressure rise and the second derivative of in-cylinder pressure in different conditions with the lag angle average value within system deviation. Therefore, the method based on vibration responses can be used to identify combustion timings.

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  Effect of group-hole nozzle to diesel combustion and engine performance   (in Chinese)      

  XU Cang-Su, ZHANG Le-Chao, LOU Guo-Qiang, ZHU Min-Jing, QI Fang

  2011, 2(1):  85-90.  doi:10.3969/j.issn.1674-8484.2011.01.013

  Abstract ( 2777 )   PDF (2503KB) ( 2654 )  

  Diesel combustion and emission are directly influenced by the fuel injection, atomization and mixing with air, which also influences the engine performance. Bassed on the conception and spray characteristics of a group-hole nozzle, including spray penetration, spray cone angle and atomization, the effect of a group-hole on the ignition delay, the effect of a group-hole on fuel economy, combustion noise and nitrogen oxides emission were high-lighted and analized. The research results are valuable for the design of the high-performance nozzle.

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