• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.341-345
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• 2004

A high efficiency and low device stress voltage and current clamping BVS PWM asymmetrical half bridge converter is proposed in this paper. To achieve the ZVS of power switches along the wide load range, the transformer leakage inductor $L_{Ikg}$ is increased. Then, to solve the problem related to ringing in the secondary rectifier caused by the resonance between $L_{Ikg}$ and rectifier junction capacitors, the proposed converter employs a voltage and current clamping cell, which helps voltages and currents of rectifier diodes to be clamped at the output voltage and output current, respectively. Therefore, no RC-snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. In addition, since all energy stored in $L_{Ikg}$ is transferred to the output side, the circulating energy problem can be effectively solved and duty loss does net exist. 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 425W, 385-170Vdc prototype are presented.

• Journal of Power Electronics
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• v.19 no.2
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• pp.353-362
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• 2019

To address the problem of circulating current loss in the traditional zero-current switching (ZCS) full-bridge (FB) DC/DC converter, a ZCS FB DC/DC converter topology and modulation strategy is proposed in this paper. The strategy can achieve ZCS turn on and zero-voltage and zero-current switching (ZVZCS) turn off for the primary switches and realize ZVZCS turn on and zero-voltage switching (ZVS) turn off for the auxiliary switches. Moreover, its resonant circuit power is small. Compared with the traditional phase shift full-bridge converter, the new converter decreases circulating current loss and does not increase the current stress of the primary switches and the voltage stress of the rectifier diodes. The diodes turn off naturally when the current decreases to zero. Thus, neither reverse recovery current nor loss on diodes occurs. In this paper, we analyzed the operating principle, steady-state characteristics and soft-switching conditions and range of the converter in detail. A 740 V/1 kW, 100 kHz experimental prototype was established, verifying the effectiveness of the converter through experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.10
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• pp.581-586
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• 2002

To improve the current waveform of diode rectifiers, we propose a new operating principle for the voltage-doubler diode rectifiers. In the conventional voltage-doubler rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses smaller ones and a small reactor not to boost the output voltage but improve the input current waveform. A circuit design method is shown by experimentation and confirmed simulation. The experimental results of the proposed diode rectifier satisfies the harmonic guide lines. A high input power factor of 97(%) and an efficiency of 98[%] are also obtained. The new rectifier with no controlled switches meet the harmonic guide lines, resulting in a simple, reliable and low-cost at-to dc converters in comparison with the boost-type current-improving circuits. This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. And this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit is constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduction and the power factor improvement. Half pulse-width modulated (HPWM) inverter was explained compared with conventional pulse width modulated(PWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.2
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• pp.112-120
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• 1997

The clamp mode (CM) forward zero voltage switching multi resonant converter (ZVS-MPC) with self-driven synchronous rectifier is studied. The loss at the synchronous rectification stage of the converter is analyzed using MOSFET piecewise linear model and is compared with the loss at the conventional schottky diode rectification stage of th econverter. From the results of the analysis, it is known that the use fo MOSFETs as a synchronous rectifier reduces the loss at the rectification stage overthe whole load range comparing the use of schottky diodes as a conventional rectifier in the converter. In order to verify the validit of the analysis, we have built a 33W(3.3V/10A) CM forward ZVS-MRC with self-driven synchronous rectifier, in which switching frequency is 1MHz, and tested. FRom the experimental results, it is known that the synchronous rectification achieved about 1W improvement in the loss at the rectification stage and about 3% in the efficiency at the converter as compared with the conventional schottky diode rectification.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.343-352
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• 1998

Higher frequency of energy transfer or at least energy conversion has to be used in order to reduce the size of inductors and capacitors required in the power supplies. Conventional PWM switching-mode power supplies have a limitation of operating frequency due to switching losses in the switching transistors and rectifier diodes. Means of reducing switching losses have been developed for high-frequency resonant amplifiers or more exactly dc/ac inverters. Because of smooth current and voltage waveforms resonant convertesrs havelower device switching losses and stresses lower electromagnetic interference(EMI) and lower noise than PWM converters. Therefore in this paper design equations of Classs E resonant low dv/dt rectifier with a series resonant capacitor drived using Fourier series techniques. The theory is compared with simulation results obtained for the rectifier operating at 10[MHz] ac input and 5[V] coutput.

• Journal of Power Electronics
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• v.5 no.1
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• pp.67-75
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• 2005

A high efficiency ZVS PWM asymmetrical half bridge converter for a plasma display panel (PDP) sustaining power modules is proposed in this paper. To achieve the ZVS of power switches for the wide load range, a small additional inductor L/sub 1kg/, which also acts as an output filter inductor, is serially inserted into the transformer's primary side. At that point, to solve the problem of ringing in the secondary rectifier caused by L/sub 1kg/, the proposed circuit employs a structure without the output filter inductor, which helps the voltages across rectifier diodes to be clamped at the output voltage. Therefore, no dissipative RC (resistor capacitor) snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. In addition, since it has no large output inductor filter, the asymmetrical half bridge converter features a simpler structure, lower cost, less mass, and lighter weight. In addition, since all energy stored in L/sub 1kg/ is transferred to the output side, the circulating energy problem can be effectively solved. 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 425W, 385Vdc/170Vdc prototype are presented.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.537-541
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• 2004

A high efficiency ZVS PWM asymmetrical half bridge converter for a plasma display panel (PDP) sustaining power module is proposed in this paper. To achieve the ZVS of power switches for the wide fond range, n small additional inductor $L_{lkg}$, which also acts as an output filter inductor, is serially inserted to the transformer primary side. Then, to solve the problem related to ringing in the secondary rectifier caused by $L_{lkg}$, the proposed circuit employs a structure without the output filter inductor, which helps the voltages across rectifier diodes to be clamped at the output voltage. Therefore, no dissipative RC (resistor capacitor) snubber for rectifier diodes is needed and n high efficiency as well as low noise output voltage can be realized. In addition, since it has no large output inductor filter, it features a simpler structure, lower cost, less mass, and lighter weight. Moreover, since all energy stored in $L_{lkg}$ is transferred to the output side, the circulating energy problem can be effectively solved. 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 425W, 385Vdc/170Vdc prototype are presented.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.255-260
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• 2016

In this paper, a full-wave rectifier (FWR) with a simple vibration detector suitable for use with vibrational energy harvesting systems is presented. Conventional active FWRs where active diodes are used to reduce the diode voltage drop and increase the system efficiency are usually powered from the output. Output-powered FWRs exhibit relatively high efficiencies because the comparators used in active diodes are powered from the stable output voltage. Nevertheless, a major drawback is that these FWRs consume power from the output storage capacitor even when the system is not harvesting any energy. To overcome the problem, a technique using a simple vibration detector consisting of a peak detector and a level converter is proposed. The vibration detector detects whether vibrational energy exists or not in the input terminal and disables the comparators when there is no vibrational energy. The proposed FWR with the vibration detector is designed using a $0.35-{\mu}m$ CMOS process. Simulation results have verified the effectiveness of the proposed scheme. By using the proposed vibration detector, a decrease in leakage current by approximately 67,000 times can be achieved after the vibration disappears.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.391-393
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• 2008

A modified boost converter with magnetic coupling is presented to reduce the reverse recovery loss while maintaining low conduction loss of the rectifiers. By utilizing a coupled inductor and a set of diodes, the current passing the boost rectifier is transferred to an auxiliary loop before turn-off, allowing low di/dt for reduced recovery loss. Moreover, the boost inductor is brought inside the bridge rectifier to reduce conduction loss by decreasing the number of conducting diodes during switch turn-off. Experimental results of a 500W prototype are provided to verify the increase in efficiency and validity of the proposed converter.

• Journal of Power Electronics
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• v.12 no.5
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• pp.723-730
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• 2012

This paper presents a new ZVS single phase bridgeless (Power Factor Correction) PFC, using an active clamp to achieve zero-voltage-switching for all main switches and diodes. Since the presented PFC uses a bridgeless rectifier, most of the time, only two semiconductor components are in the main current path, instead of three in conventional single-switch configurations. This property significantly reduces the conduction losses,. Moreover, zero voltage switching removes switching loss of all main switches and diodes. Also, auxiliary switch turns on zero current condition. The presented converter needs just a simple non-isolated gate drive circuitry to drive all switches. The eight stages of each switching period and the design considerations and a control strategy are explained. Finally, the converter operation is verified by simulation and experimental results.