• Journal of Power Electronics
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• v.1 no.2
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• pp.107-116
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• 2001

Two AC-DC PWM full-bridge converters that can input current to improve input power factor while performing dc-dc conversion are investigated in this paper. Both converters are simple in that they are similar to the standard PWM full-bridge converter with a diode rectifier/LC low-pass filter input, and both can operate with a simple method of PWM control. In the paper, the operation of the converters is explained and their steady-state characteristics are discussed. The feasibility of the converters and their ability to meet EN61000-3-2 Class D Standards for electrical equipment are shown with results obtained from experimental prototypes. The performance of both converters in terms of dc bus voltage level, input power factor and efficiency is compared and discussed.

• Transactions on Electrical and Electronic Materials
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• v.7 no.3
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• pp.103-107
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• 2006

In this paper, a CMOS complementary bridge rectifier for driving RFID transponder chips is presented. The proposed RFID CMOS complementary bridge rectifier is designed with two NMOSs at the input, which are configured by cross-connected gate structures, and two PMOSs and two NMOSs at the output, which are configured by diode-connected MOS structures. Output characteristics of the proposed rectifier are analyzed with the high frequency small-signal equivalent circuit and verified with SPICE for RFID operating frequencies of 13.56 MHz HF for ISO 18000-3, 915MHz UHF for ISO 18000-6, and 2.45 GHz microwave for ISO 18000-4. Simulation results show well-rectified and high enough DC output voltages for driving the low power microchip in the RFID transponder for the frequency range from HF to microwave. DC output voltages are dropped by only around 0.7 V from the input peak-to-peak voltages.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.425-432
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• 2020

The phase-shifted, full-bridge (PSFB) DC-DC converter is widely used in electric vehicles (EVs) to charge a low-voltage (12 V) battery from a high-voltage battery. A Photovoltaic (PV) module-integrated PSFB converter is proposed for the EV power conversion system. The converter is useful because solar energy can be utilized to extend the driving range. The buck converter circuit is simply realized by adding one switch to the conventional PSFB converter's secondary side. For the inductor and diode, the existing components in the PSFB converter are shared. The proposed converter can charge a low-voltage battery from the PV module with maximum power point tracking. In addition, the two power sources can be used simultaneously, and efficiency is increased by reducing the circulating current, which is a problem for the conventional PSFB converter.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.619-623
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• 2004

We proposed the bridge type superconducting fault current limiter(SFCL) using switching operation of high-Tc superconducting(HTSC) thin film. The proposed bridge type SFCL consists of HTSC thin film, a diode bridge and a dc reactor. The controller for the operation of an interrupter is required in the conventional bridge type SFCL to prevent the continuous increase of fault current after a fault happens. On the other hand, the proposed bridge type SFCL can limit the fault current without the interrupter and the controller for its operation by the resistance generated when the gradually increased fault current exceeds HTSC thin film's critical current. We calculated the time when the gradually increased fault current started to be limited by the resistance generated in HTSC thin film after a fault happened and confirmed that it could be dependent on the amplitude of source voltage. The experimental results well agreed with the calculated ones from simulation.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.277-279
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• 2005

Generally, It was used to use a unit of a Large regularity in developing Large Capacity Converter System of the electric power. Lager a capacity of a unit of regularity, more expensive cost of it. So, normally, We overcome the limit of a proper form of an electricity semiconductor which be used in application field of Large capacity electricity conversion system through the Composition of Multi-level Circuit or Dual-Mode or parallel switch. but some problem is discussed. Using parallel RC-diode circuit instead of Large Capacity diode, We implemented a circuit that it overcome the limit of a regularity with dealing current distributed by parallel RC-diode circuit.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2109-2111
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• 1998

This paper proposes a new lossless snubber circuit on power supply for welding machine's output rectification diode. To improve the common inverter control type power supplies' problems that energy loss and heating in the snubber circuit because the output capacity makes too big heat energy in the circuit when the output current of the inverter is rectified by the diode bridge circuit, which includes the snubber circuit. This paper suggested new snubber circuit have increased power factor and confidence of output by being regenerate thus lost energy to input node.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.451-462
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• 2016

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.351-355
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• 2016

Welding machines are high-capacity systems used in a low-frequency range using IGBT. As their system is similar to a large transformer, most welding machines suffer a great loss because of hard switching and vast leakage inductance. A voltage-balancing circuit is designed to overcome these shortcomings. This circuit can reduce the transformer size by making it into a high frequency and reducing the input voltage by half and by adopting a serial structure that connects two full-bridges in a series to use a MOSFET with a good property at high frequency. In addition, a Schottky diode is used in the primary rectifier to overcome the low efficiency of most welding machines. To use the Schottky diode with a reliably relatively low withstanding voltage, an active snubber is adopted to effectively limit the ringing voltage of the diode cut-off voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.82-82
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• 2009

현재 국내에는 많은 가구들이 전기를 사용하고 있다. 아파트, 주택에 들어가는 전기 시스템들이 많이 발전하였지만 뜻하지 않은 사고로 인해 정전이 되는 경우가 있다. 정전시에는 아파트 같은 경우는 비상등, 엘리베이터 등 최소한의 장치만이 작동하도록 되어있다. 그러므로 각 세대에는 전기가 들어가지 않는다. 우리나라 경우에는 태풍이나 여름 같은 경우에는 전기를 많이 사용하기 때문에 발전기가 과부화 걸리는 현상이 생기기도 한다. 장기간 정전시에 가장 문제가 되는 기기는 냉장고, 전등이 될 것이다. 냉장고 같은 경우는 음식들이 상하게 되고, 전등 같은 경우에는 밤에 활동하는데 지장을 주게 된다. 따라서 본 논문에서는 정전시에는 자동적으로 비상발전기의 전원을 사용하고, 상시에는 다시 한전의 전원을 사용하게 하는 초소형 자동 스위칭 전원 모듈을 설계 제작한 논문이다. 설계된 스위칭 모듈에 대해서 시뮬레이션한 결과 예상한대로 비상시에 자동적으로 스위칭되는 결과를 알 수 있었다.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1706-1715
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• 2016

In this paper, a single phase modified switched-diode topology for both symmetrical and asymmetrical cascaded multilevel inverters is presented. It consists of a Modified Switched-Diode Unit (MSDU) and a Twin Source Two Switch Unit (TSTSU) to produce distinct positive voltage levels according to the operating modes. An additional H-bridge synthesizes a voltage waveform, where the voltage levels of either polarity have less Total Harmonic Distortion (THD). Higher-level inverters can be built by cascading MSDUs. A comparative analysis is done with other topologies. The proposed topology results in reductions in the number of power switches, losses, installation area, voltage stress and converter cost. The Nearest Level Control (NLC) technique is employed to generate the gating signals for the power switches. To verify the performance of the proposed structure, simulation results are carried out by a PSIM under both steady state and dynamic conditions. Experimental results are presented to validate the simulation results.