A new snubber circuit for high efficiency and overvoltage limitation in three-level GTO inverters

1997 ◽  
Vol 44 (2) ◽  
pp. 145-156 ◽  
Author(s):  
Jae-Hyeong Suh ◽  
Bum-Seok Suh ◽  
Dong-Seok Hyun
Keyword(s):  
High Efficiency ◽  
Snubber Circuit

Simulation of Modified Flyback Snubber Circuit for Isolated Bidirectional DC-DC Converter

2018 ◽  
Vol 19 (5) ◽  
Author(s):  
Kunalkumar Prakashbhai Bhatt ◽  
Ram Avtar Gupta ◽  
Nitin Gupta
Keyword(s):  
High Efficiency ◽  
Semiconductor Devices ◽  
Soft Switching ◽  
Leakage Inductance ◽  
Snubber Circuit ◽  
Mode Of Operation ◽  
Active Clamp ◽  
Semiconductor Switch ◽  
Effective Performance ◽  
Current Difference

Abstract Abstract: In this paper, a modified flyback snubber circuit for isolated bidirectional DC-DC converter has been introduced. The soft switching isolated snubber circuit provides an alternative path for the current difference created due to source inductance and leakage inductance. The auxiliary snubber circuit operates during the step-up conversion, and it only persists of the two semiconductor switch, two inductors one diode and two capacitors. Both semiconductor devices (G1, G2) of flyback snubber circuit achieve soft switching during turn ON and turn OFF condition. The PWM technique has been used to control the semiconductor devices. The different mode of operation has been discussed in detail. The effective performance of proposed converter system has been validated with the PSIM simulation tool. The proposed converter is compared with the active clamp converter based on efficiency. The loss comparison proves that flyback snubber circuit has high efficiency compared to active clamp converter.

scholarly journals Non-Dissipative Snubber Circuit Based SEPIC Converter for High Static Gain Applications

2020 ◽  
Vol 8 (6) ◽  
pp. 754-757
Keyword(s):  
High Efficiency ◽  
Semiconductor Device ◽  
Semiconductor Devices ◽  
Sudden Change ◽  
The Other ◽  
Efficient Operation ◽  
Power Semiconductor ◽  
Turn On ◽  
Power Semiconductor Devices ◽  
Snubber Circuit

In this paper different non-dissipative snubber circuits in which RCD snubber circuit, CD snubber circuit, LCD snubber circuit and proposed LCD snubber circuit are implemented in SEPIC converter to obtain high static gain. The snubber circuit is used for the protection of the power semiconductor devices. The requirement of high static gain is necessary in different applications of dc-dc converters, so that efficient operation of the system can be obtained. The basic idea of the snubber circuit used in this paper is to reduce the turn-on and turn-off losses at the time of switching processes. For this purpose, inductor and capacitor combination is required so that during turn-on process, sudden change in current through semiconductor device which is used as a switch, can be reduced. Similarly, during turn-off process, sudden change in voltage across switch can be minimized. Here, different snubber circuit based SEPIC converters are analyzed with the help of MATLAB simulink and results of output voltages and currents are obtained. The results are summarized which clearly shows that the proposed SEPIC converter has high static gain in comparison of the others topologies. Hence non-dissipative snubber circuit based SEPIC converter provides high efficiency than the other modifications in SEPIC converter.

High Efficiency DC-DC Buck Converter with a Passive Snubber Circuit

2019 ◽  
Author(s):  
Jung-Ha Kim ◽  
Sang-Won Lee ◽  
Hyeon-Seok Lee ◽  
Sang-Hoon Lee ◽  
Yoon-Geol Choi ◽  
...  
Keyword(s):  
High Efficiency ◽  
Buck Converter ◽  
Snubber Circuit

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

The use of high-resolution FESEM to study solid-state phase transformations and reactions

1994 ◽  
Vol 52 ◽  
pp. 1028-1029
Author(s):  
P. G. Kotula ◽  
D. D. Erickson ◽  
C. B. Carter
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Phase Transformations ◽  
High Efficiency ◽  
Sol Gel ◽  
Quantitative Information ◽  
Solid State Reactions ◽  
Critical Dimensions ◽  
Backscattered Electrons ◽  
Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

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