Papers by Keyword: Electric Field

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Authors: Akio Shima, Haruka Shimizu, Yuki Mori, Masakazu Sagawa, Kumiko Konishi, Ryusei Fujita, Takashi Ishigaki, Naoki Tega, Keisuke Kobayashi, Shintaroh Sato, Yasuhiro Shimamoto
Abstract: We investigated improvement ways of to overcome these reliability issues in a 3.3 kV 4H-SiC DMOSFET. JFET doping with (i) narrow width and (ii) deeper depth than that of the p-well region successfully reduced the electric field in the gate insulator and the on-voltage simultaneously. We achieved a low Ron of 26 mΩcm2 at a Vg of +15 V and 150 °C. And highly reliable chips of 0.1 Fit were also achieved both at a positive and negative gate bias of +15 V/ -8 V with MTTF of intrinsic lifetime over 20 years at 3 MV/cm. BTI characterstics both in positive and negative biases also proved reliability over 20 years. The body diode showed stable behavior under forward current operation which is suitable for an external diode-less power module.
Authors: Mahdi Hassani, Seyed Siavash Karimi Madahi, Hassan Feshki Farahani, Hossein Sarabadani
Abstract: Capacitor bushings are one of the key components in power transformers. Although their price is a negligible part of the total price of the power transformer, their quality has a significant effect on performance and reliability of power transformers. In high voltage capacitor bushings, the intensity of voltage and electric field on bushing abacus is very high. This high intensity is also observed in flange parts. The amount of multi layer insulator among the electrodes or floating plates in capacitor bushing make equi-potential surfaces and reduction of electric field in these areas can greatly improve the capacitor bushing performance. In this paper, we investigate the reduction of field intensity and electrical tension and also improvement in voltage control by displacing floating plates which are in the form of aluminum foils stick to impregnated paper. To calculate the field intensity, we used the MAXWELL software using FEM (Finite element method). Using this new method of placing capacitor core its effect on voltage profile reduction and field electrical tension is shown. Over voltage and pollution effects are also investigate on power transformer bushings.
Authors: Bo Tao Sun, Li Xin Wang, Yan Fei Zhang, Li Mei Song, Wei Xiong
Abstract: In this work, a new charge-coupling structure of RSO MOSFET with slope field plate is proposed. The design method is developed by theoretical analysis. In addition, a fabrication method using multi-plate to fit slope method is introduced. Then, a 250V structure was simulated to verify the theoretical analysis by TCAD. It is demonstrated that the structure overcomes the non-uniformity of electric field in drift region in traditional RSO MOSFET. The trade-off between the Ron and BV— “silicon limit” has been broken, for the Rdson=116 mΩ/mm2 in this structure.
Authors: Hua Bin Wen, Yong Duan Song, Rui Li
Abstract: The optimal design of vacuum switch is becoming an important research topic with the extensive application and increasing demands of vacuum switches. This paper analyzes the main elements of the vacuum switch design, and gives the design process of the vacuum switch. An optimal design method is proposed for the vacuum switch based on the concept and characteristics of virtual prototyping (VP) technology. By using computer aided design and the related software, we propose a method for vacuum switch modeling VP, the stress field VP of parts, the thermal field VP of electric heat, the electric field VP of insulation parts and the mechanical dynamic VP of kinematics system, which are integrated for optimization design for vacuum switches. This work is expected to provide a new idea for optimal and rapid design of vacuum switches.
Authors: I. Ostrovskii, O.A. Korotchenkov
Authors: Ji Le Jiang, Yu Tian, Yong Gang Meng
Abstract: A preliminary study of active friction control method based on electrorheological (ER) effect is experimentally investigated. The friction coefficient can be changed from 0.07 to 0.9 continuously with the applied voltage in the range of 0 to 2000 V. Results show that by using proper ER fluids and structure design, active friction control based on ER effect has good potential in real industrial applications.
Authors: Xian Qin, Qing Yuan Meng, Yu Fei Gao
Abstract: The adsorption of H2S molecule on Si-doped and Ag supported Si-doped graphene is studied by first-principles calculations. We find that the H2S floats on the Si-doped graphene sheet, indicating a weak physisorption. The calculated net charge transfer, charge density difference and density of states give evidence that the adsorption of H2S on Ag supported Si-doped graphene is by chemisorption. Moreover, the desorption and dissociation of H2S adsorbed on Ag supported Si-doped graphene occur at the external electric field of 1.4 and -0.8 V/Å, respectively. Therefore, the Ag supported Si-doped graphene can be expected to be a novel sensor for the detection of H2S gas.
Authors: Yan Xu, Wei Chen, Kai Leung Yung
Abstract: The most apparent advantages of thermoplastics are the recyclability and processibility. To obtain recyclable and injectable conductive polymer, this paper studied the filling of carbon nanotubes (CNT) in polystyrene(PS) and the aligning of CNT in PS under high frequency electric field and ultrasonic vibration using an experimental set up developed in our laboratory. Results of these studies would be very useful to the development of a new generation of micro fabrication method for producing integrated micro electronic products using micro injection molding that is the most cost effective way to produce micro products massively.
Authors: Zhi Guang Dong, Zhi Hui Dong
Abstract: The effects of an ununiform electric field on bubble behaviours such as bubble growth ,deformation and detachment are investigated experimentally.Experimental results show that the bubble elongated along the direction of the electric field.The bubble’s aspect ratio is increased with the increasing of electric field intensity and the ellipse sphere shape is more evident than without electric field,while its departure volume is decreased with that.The case is the bubble comes under the electric stress.The electric stress compressed the bubble in the equatorial direction and extened the bubble along the axial direction.The bubble behaviours influenced in the ununiform electric field is more evident than the uniform electric field.
Authors: Yuan Yuan Ge, Fu Yuan Wang, Ai Mei Zhang, Su Tao Zhuang
Abstract: In this paper, in order to make the simulation of the whole process of electrochemical machining(ECM), the characteristic of electric field and flow field is made detailed analysis in the gap of ECM. Mathematical-physical models of ECM simulation is set up based on the basic theories of electrochemistry, electric field and flow field. And the method of model solution is discussed and researched. So the theoretical base is established of the full process of ECM simulation.
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