Papers by Keyword: High Voltage

Abstract: This work shows thermal simulations of a package of 48/96 high-voltage (6.5 kV/1 kA) PiN diodes. A temperature dependent heat generation for a forward voltage of 3.6 V with a realistic heat generating volume in the diode of (2.7x2.7x0.01) mm3 was used. The thermal coupling of two diodes was determined to be less than 1 % for a distance between the diodes of 10 mm. The temperature distribution for the entire module has been studied for two different ceramic insulating materials, AlN and Al₂O₃, as well as for two numbers of diodes, 48 and 96. This led to a maximum temperature of 106 °C/118 °C (AlN, 48/96 diodes) and 123 °C/144 °C (Al₂O₃, 48/96 diodes). Assuming a constant applied voltage, a variance of ±0.5 V of the characteristic curve (forward voltage versus current) due to variations in the production process was considered fork single diodes. For a shift of +0.5 V for a single diode, the maximum temperature difference to the cooler temperature becomes approximately twice the original difference. Additionally, the operation under constant current (7.1 A, 10.2 A, 14.2 A) was studied including single diode failure. For single diode failure, the resulting change of the maximum temperature would be less than 3 %.

Abstract: High gain photoconductive switching using Si and GaAs was studied previously for pulsed high voltage switching. A laser is used to generate charge carriers within the material to render the bulk conductive. We have begun the study of photoconductive switching using wide bandgap materials. These materials appear to operate in a non-high gain mode and the on resistance can be directly controlled with the laser intensity over many decades. It is presently believed that the conduction mechanism may be due to (a) excitation of deep states or (b) multi-photon pumping of carriers from the valance band. We present the study of the physics processes and development of a device operating at >20-kV.

Abstract: This paper summarizes the application situation of the ultra-high frequency (UHF) method in gas insulated switchgear (GIS) partial discharge detection, as well as the differences between internal and external UHF sensors. The performance indicators of internal sensors are introduced, and five main types of internal sensors are discussed and evaluated. In addition, several problems to be solved are posed for researchers.

Abstract: TGZ10A-40.5 wall bushing of high voltage switch cabinet from one company was taken as applied research object. Reference the development process of high voltage cable shielding technology, three samples were designed and produced depending on different sets of the shield system. The result show that: surfaces processed by the way that the inner (aluminum cylinder) and the outer (metal mesh ring) shielding components were coated with a semi-conductive material, made little sense to improve the withstand voltage level and reduce the partial discharge; surface processed by the way that inner shield component (aluminum cylinder) was coated with semi-conductive material, the outer shield component (metal mesh ring) was not coated with semi-conductive material, was obviously influenced the improvement of the withstand voltage level and reduction of the partial discharge, compared with traditional technology, the average start voltage of corona increased 23.8%, the average value of partial discharge dropped 27.7%.

Abstract: AlF₃ and MgF₂ were applied to modify the surface of the LiNi_1/3Co_1/3Mn_1/3O₂ cathode material. The structural and electrochemical properties of the materials were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), charge–discharge tests and electrochemical impedance spectra (EIS). The results show that the 1 wt.% AlF₃ and 1 wt.% MgF₂ coated LiNi_1/3Co_1/3Mn_1/3O₂ (NCM333) cathode material exhibits an optimized electrochemical performance. It presents an initial capacity of 207.2mAh/g and 169.1mAh/g at 0.2C between 2.8V and 4.7V after charge-discharge 65 cycles. The rate performance is also enhanced because the coating decreases the interface charge transfer impedance.

Abstract: 3.3kV and 4.5kV 4H-SiC junction barrier Schottky (JBS) diodes with floating guard rings edge termination have been fabricated. The 3.3kV device with 33μm 2.7E15 cm^-3 epilayer and 5.5Х5.5mm² schottky contact area has a blocking voltage (V_b ) of 3.9 kV and a specificon-resistance (Ron) of 10.5 mΩ.cm², with a forward current measured up to 50A at V_F=3.0V. The 4.5kV device with 50 um 1.2E15 cm^-3 epilayer and 5.5Х5.5mm² schottky contact area has a blocking voltage (V_b ) of 5.1 kV and a specificon-resistance (Ron) of 22.9 mΩ.cm², with a forward current of 30A at V_F=3.7V.

Abstract: In general, transformer is one of the most important equipment in the power system, the reliability of a transformer is commonly determined by its insulation condition. The insulation liquid that has been used for decades is petroleum based mineral oil which has a very good cooling performance. However, it is insidious to the environment. Hence, vegetable oils such as coconut oil and palm oil are used as the alternative to replace the mineral oil. In this paper, it presents the comparative studies from previous experiments on dielectric strength, moisture content, viscosity, pour point and flash point of both vegetable oils.

Abstract: The theoretical analysis and numerical simulation of electron beam generation in foil-less diode are presented. The theories of OAL, CL, and equilibrium beam model are briefly compared. All the theoretical models can give a relatively accurate solution of electron gun, and the equilibrium beam model is more appreciated. A PIC simulation tool UNIPIC is introduced and is used to analyze the behaviors of a foil-less diode. Under the conditions of 180 kV incident voltage wave and 2.5 T axial magnetic fields, we obtained the 250 kV, 1.5 kA output beam current which can be used in high power microwave generators.

Abstract: Aiming at the application requirements of miniaturization and energy saving in the field of high voltage power supply, a high voltage switching power supply with soft switching technology was designed. The soft switch technology which makes the loss of switch power supply decrease obviously,and the dual voltage rectifier technology can effectively reduce the volume of switching power supply. Circuit parameters of switching power supply are optimized in order to further improve the efficiency of power supply. From the experiment results, the high voltage switching power supply meets the design requirements, and suitable for the strict requirements of environment on the volume and efficiency.

Abstract: A numerical simulation of electric and hydrodynamic field’s distribution in an electrohydrodynamic pump is made, with the mean to simulate and to determine numerically the liquid pressure and velocity. Different parameters of the pump are analyzed.