2015, 4(1):1-7. DOI: 10.12146/j.issn.2095-3135.201501001
Abstract:On demand of a sustainable, green, and low-carbon economy development, there is a worldwide stimulation on the progress of Electric Vehicle (EV) industry. The wireless charging technique, embodying advantages of convenience, safety and low-maintenance, has been gaining interests from both the academia and industrial community. It is promising to be the future trend for the EV charging technology. And the magnetic coupler which enables wireless charging is the most essential part in a wireless charging system. In this paper, the latest research progress in the development of EV oriented wireless charging system, especially the magnetic coupler, which is the most important unit, was reviewed internationally. Besides, the pioneering deployments and commercializing trial of the wireless charging system using EV was highlighted as well. At last, challenges to be addressed and perfections to be made in the near future on the magnetic coupler were summarized.
2015, 4(1):8-15. DOI: 10.12146/j.issn.2095-3135.201501002
Abstract:Electric vehicle is an effective solution to the fossil fuel energy resource crisis and environmental pollution, but there is a wide gap between current market conditions and the anticipated products. However, low-speed electric vehicles have been commercially successful in the low-end performance electric vehicle market in China. In this paper, the ride characteristics, dynamic performance, battery performance, and power efficiency of a low-speed electric vehicle were examined. The vehicle characteristics were measured through dynamometer and road tests. The overload performance was also tested under the drive power more than 4 times the rated value. The effects of different batteries on the cost performance of low-speed electric vehicles were also analysed. Although the lithium-ion polymer battery is currently more costly than the lead-acid battery, the increased efficiency of this battery provides a more economical full-cycle lifetime driving distance for practical applications. The low power efficiency of the DC drive motor and its control system limit the general power efficiency of the low-speed electric vehicle and determine its economical speed. Some optimisation methods for improving low-speed electric vehicle performances were suggested.
2015, 4(1):16-24. DOI: 10.12146/j.issn.2095-3135.201501003
Abstract:Increasingly serious environmental problems have prompted the city traffic to the clean, efficient and sustainable directions, and have also accelerated the popularization and applications of the new energy transport technology. With the development of the battery and motor drive technology, battery electric buses have drawn extensive concerns. Starting acceleration performance and regenerative braking capability are two advantages of battery electric bus compared to traditional vehicles. Because of quick responses of the accelerator pedal signal and drive motor, the acceleration performance of battery electric bus is superior to the traditional diesel bus theoretically. The regenerative braking is an important technique to save energy consumption and extend the drive range. In this paper, based on the fuzzy logic algorithm, we designed a driving torque control strategy for decreasing the starting acceleration time. Meanwhile, the regenerative braking control strategy is reported. The results show that, the driving torque control strategy can decrease acceleration time and the regenerative braking strategy can save energy consumption by 11% during the Chinese city bus driving cycles.
2015, 4(1):25-36. DOI: 10.12146/j.issn.2095-3135.201501004
Abstract:The high-fidelity numerical simulation of unsteady flows around cars are a very challenging computational problem because of the huge computation caused by high Reynolds number and complex geometry. In this paper, we presented a scalable parallel Newton-Krylov-Schwarz based fully implicit algorithm for the full unsteady incompressible flows around cars and compared our results with results obtained from commercial CFD software. Our algorithm shows very good parallel scalability on a supercomputer with over two thousand processors.
2015, 4(1):37-43. DOI: 10.12146/j.issn.2095-3135.201501005
Abstract:The state of the researches on automated mechanical transmission (AMT) technologies conducted in China in recent years were briefly reviewed in this article. The progress made on some of the key technologies, especially in such areas as shift control, launch control, and shift schedule was summarized. The development of technologies in clutchless shifting and shifting without disengaging the clutch was also elaborated.
2015, 4(1):44-50. DOI: 10.12146/j.issn.2095-3135.201501006
Abstract:Hydrate salt is an attractive solid-liquid phase change material because of its high energy storage density. However, its applications have been limited owing to the supercooling and phase segregation. In order to solve these problems, we propose to make the silica gel in the saturated solution of sodium sulfate by means of in-situ polymerization. According to our experiments, the latent heat of saturated solution of sodium sulfate in silica gel is about 238.1 J/g and the phase change temperature is 30℃. With some surfactant, it can endure more than five months of heating-cooling cycles stably in subtropical spring and summer. Using scanning electron microscope and Fourier transformation infrared spectroscopy, we found that the microstructure of silica gel was mainly amorphous with some small crystals distributed in it. We believe that adding the silica gel produces a porous structure, which helps the crystal growth of sodium sulfate hydrate and hence, suppresses the supercooling and phase segregation.
2015, 4(1):51-59. DOI: 10.12146/j.issn.2095-3135.201501007
Abstract:In this work the thermal behavior of the LiNi1/3Co1/3Mn1/3O2 cathode material for soft packed lithium-ion power batteries during charging and discharging at different C-rate were conducted using the ARC (accelerating rate calorimeter) to provide an adiabatic environment. The overall heat generated by the lithium-ion battery during use, is partly reversible and partly irreversible, due to entropy change and joule heating, respectively. It indicates that the heating generation of lithium-ion cell is decided by the C-rate of charge and discharge. The heat is smaller at low C-rate of charge and discharge. For example, the heating generation of battery increases 7.16℃ at 0.2C-rate and the entropy change heat is clearly embodied. The joule heating is more remarkable than the entropy change during charging and discharging at high C-rate. For instance, the heating generation of cell increased 25.63℃ at 1C-rate. The heat generation of charge is less than discharge at the same C-rate. The DC inter insistence of cell at the SOC (State of Charge) of 0 to 10% increases suddenly, so the heating generation power will reach its maximum in this period during discharge. It is valuable for the design of heat dissipation in lithium-ion battery thermal management.
2015, 4(1):60-66. DOI: 10.12146/j.issn.2095-3135.201501008
Abstract:The emission experiments of LNG (Liquefied Natural Gas) bus and Hybrid bus on urban roads were carried out with high-precision mobile emission tester. Then the vehicles’ emission characteristics were analyzed. Experimental results show that the CO emission of the LNG vehicle is less than that of the hybrid vehicle, and NOx emissions are relatively close to each other, while the HC emission of the LNG bus is far higher than that of the hybrid bus. Three emission factors of LNG vehicle decrease with the increase of speed, but the emission rates are different with the change of speed and acceleration. Due to the mode of pure electric start and motor auxiliary accelerating of the hybrid bus, the emissions of the three pollutants achieve the least at the speed of 15-20 km/h, and CO and HC emissions reach their maximums at the acceleration of 0 while the NOx emission reach its maximum at the acceleration of around 0.5 m/s2.
2015, 4(1):67-73. DOI: 10.12146/j.issn.2095-3135.201501009
Abstract:The performance of automotive under specific drive cycles can provide a reference for the development and improvement of vehicle systems. At present, there is no representative typical driving cycle in Shenzhen. In this paper, the development of M347 bus route driving cycle in Shenzhen was reported, combining principal component analysis and clustering analysis methods, and the rationality and the validity of the driving cycle were tested and verified. The original micro-trips are divided into two series by the clustering analysis method, which may explain traffic jam and smooth traffic driving conditions of M347 bus route. The M347 route multiple driving cycle constructed at last can reflect the real-world road conditions.
2015, 4(1):74-82. DOI: 10.12146/j.issn.2095-3135.201501010
Abstract:With the characteristic of low coefficient of thermal expansion, high heat resistance, high wet resistance and low dielectric constants, silica could effectively reduce the coefficient of thermal expansion, water absorption, contraction ratio and inner stress of epoxy resin. So, silica has been widely used in the field of electronic packaging. The Sol-Gel methods developed in recent years for preparation of silica spheres, the process factors, and the study of being filled with epoxy resin were reviewed in this article. And the problems and development direction of silica applied in the field of electronic packaging were pointed out as well.
2015, 4(1):83-91. DOI: 10.12146/j.issn.2095-3135.201501011
Abstract:To develop electric vehicles is a way to reduce fossil fuel and alleviate air pollution. But a large scale of electric vehicles will bring a serious impact on the stability of grid, such as the peak widening, voltage deviations and the increase of energy losses. It is well known that it will cost much for the extension and renovation of the grid while smart charging can efficiently solve this problem without radical transformation of the grid. Smart charging of electric vehicles can not only bring economic benefits to the power company, but also benefit customers of electric vehicles. In this paper, the two main control architectures of smart charging, the centralized control and the decentralized control were reviewed. The research of centralized control is based on various targets, such as minimizing operating costs, minimizing energy loss or minimizing load variance. And the decentralized control mainly depends on the price mechanism to motivate users to change their charging behaviours. Finally, the integration of electric vehicles and renewable energy were introduced and the constructions of network communication devices were described.