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Proceedings ArticleDOI: 10.1109/ICCPEIC.2016.7557298

High gain, naturally clamped Dc to Dc converter for X-ray application

20 Apr 2016-pp 587-592
Abstract: The paper presents a novel converter for a medical X-ray machine application. A resonant, current fed inverter is proposed. The high voltage transformer step up ratio is kept very low to reduce the effects of its leakage inductance and other non-idealities. Moreover this leakage inductance and the parasitic capacitance of HV transformer and switches are used as resonating components for attaining a soft switched conversion. The switches are soft switched with ZCS, which works over a wide load range. A set of Cockroft Walton multiplier is employed on the secondary side of the transformer accomplishes the final output. The converter operates at 100 kHz frequency with overlap time switching to achieve 100kV and 2.5 mA required by the X-ray machine. A very systematically elaborated analysis for selection of every discrete component in this particular topology is discussed in this paper. more

Topics: Forward converter (66%), Leakage inductance (65%), Flyback converter (64%) more

Proceedings ArticleDOI: 10.1109/COBEP.2017.8257407
01 Nov 2017-
Abstract: This paper presents the steady state and resonant current analysis of a Forward-Flyback Voltage Multiplier operating in discontinuous conduction mode. The operation stages are approached, taking into account the resonant current. The static gain and the conditions for the operations modes are obtained. A sinusoidal approximation is proposed to represent the resonant current with respect to the number of stages, voltage multiplier capacitors and leakage inductance. The characteristics of voltage sharing among capacitors, that allows the use of small voltage components, and the high-gain with reduced turns of the transformer are verified. Bench tests were made for a 200 V/2000 V prototype, from one to five stages, highlighting the overall circuit effects for a 200 W output power. Obtained waveforms for different number of voltage multiplier stages validate the theoretical and simulated results, making this converter an alternative to isolated DC/DC systems where the output voltage must be higher than the input voltage. more

Topics: Voltage multiplier (69%), Flyback converter (65%), Buck converter (60%) more

4 Citations

Proceedings ArticleDOI: 10.1109/IMITEL.2018.8370479
18 Apr 2018-
Abstract: The article describes the phenomena occurring in the Half-Wave Cockcroft-Walton voltage multiplier when it is supplied through a transformer by an inverter with a rectangular shape of output voltage. The frequency of the inverter output voltage was selected so that a series resonant phenomena occurs in the system. They are caused by the presence of voltage multiplier capacitors and transformer leakage inductances. In the article the characteristics and waveforms of voltages and currents obtained by simulations are presented. The results of simulations were used to build two prototypes with maximum powers of about 60 W and 160 W and a 40 kV output voltage. more

Topics: Voltage multiplier (65%), Transformer (53%), Capacitor (53%) more

2 Citations


Journal ArticleDOI: 10.1109/28.536876
02 Oct 1994-
Abstract: Many industrial and military applications are arising that require high power DC-DC conversion. These applications include shipboard, spaceborne, and transportation power systems. By employing new high voltage, high power IGBTs, along with modern soft-switching techniques, the switching frequency can be significantly higher than obtained using GTO devices, which in turn can lead to smaller, lighter weight, and potentially more cost effective equipment. The purpose of this paper is to compare the properties of several soft-switching converter topologies when used to achieve DC-DC conversion at high power and high voltage levels. As an example, a 100 kW transformer isolated converter with 700-1400 V DC input is designed with an estimated weight in the 200 pound range and an energy efficiency of 95%. > more

Topics: Boost converter (64%), Switched-mode power supply (64%), Electric power system (57%) more

222 Citations

Journal ArticleDOI: 10.1109/TPEL.2005.857525
Sang-Kyoo Han1, Hyun-Ki Yoon1, Gun-Woo Moon1, Myung-Joong Youn1  +2 moreInstitutions (2)
Abstract: A new active clamping zero-voltage switching (ZVS) pulse-width modulation (PWM) current-fed half-bridge converter (CFHB) is proposed in this paper. Its active clamping snubber (ACS) can not only absorb the voltage surge across the turned-off switch, but also achieve the ZVS of all power switches. Moreover, it can be applied to all current-fed power conversion topologies and its operation as well as structure is very simple. Since auxiliary switches in the snubber circuit are switched in a complementary way to main switches, an additional PWM IC is not necessary. In addition, it does not need any clamp winding and auxiliary circuit besides additional two power switches and one capacitor while the conventional current-fed half bridge converter has to be equipped with two clamp windings, two ZVS circuits, and two snubbers. Therefore, it can ensure the higher operating frequency, smaller-sized reactive components, lower cost of production, easier implementation, and higher efficiency. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200-W, 24-200Vdc prototype are presented. more

Topics: Switched-mode power supply (58%), Snubber (58%), Pulse-width modulation (53%) more

196 Citations

Journal ArticleDOI: 10.1109/63.558774
Kevin M. Smith1, Keyue Smedley1Institutions (1)
Abstract: A comparison study was conducted to characterize the loss mechanisms, component stresses, and overall efficiencies of a group of voltage-mode soft-switching pulse width modulation (PWM) methods, including two methods developed by the authors. All soft-switching methods in the selected group allow zero voltage turn-on and turn-off of the main switch and utilize a single auxiliary switch with some resonant components. Advantages and disadvantages are identified for each method. Experimental verification for each soft-switching method is provided. It was found that only those methods that softly switch the auxiliary switch, minimize redirection current, and recover the auxiliary circuit energy improve efficiency over most of the load range. more

165 Citations

Journal ArticleDOI: 10.1109/TEC.2006.874208
Abstract: In this paper, a new active clamping current-fed half-bridge converter is proposed, which is suitable for fuel cell power generation systems. The proposed converter is superior to conventional dc-dc converters in terms of efficiency and component utilization. The overall efficiency is estimated to be 94% at full load. more

Topics: Buck–boost converter (63%), Ćuk converter (63%), Boost converter (62%) more

164 Citations

Journal ArticleDOI: 10.1109/TIE.2012.2188255
Chung-Ming Young1, Ming-Hui Chen1, Tsun-An Chang1, Chun-Cho Ko1  +1 moreInstitutions (2)
Abstract: This paper proposes a high step-up dc-dc converter based on the Cockcroft-Walton (CW) voltage multiplier without a step-up transformer. Providing continuous input current with low ripple, high voltage ratio, and low voltage stress on the switches, diodes, and capacitors, the proposed converter is quite suitable for applying to low-input-level dc generation systems. Moreover, based on the n-stage CW voltage multiplier, the proposed converter can provide a suitable dc source for an n + 1-level multilevel inverter. In this paper, the proposed control strategy employs two independent frequencies, one of which operates at high frequency to minimize the size of the inductor while the other one operates at relatively low frequency according to the desired output voltage ripple. A 200-W laboratory prototype is built for test, and both simulation and experimental results demonstrate the validity of the proposed converter. more

Topics: Forward converter (71%), Flyback converter (70%), Boost converter (69%) more

159 Citations

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