• 한국철도학회논문집
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• 제15권2호
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• pp.116-121
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• 2012

DC/DC스위칭 전력 컨버터는 임의의 직류전원을 부하가 요구하는 형태의 직류전원으로 변환시킨다. DC/DC 컨버터는 PWM-IC를 이용하여 주기적으로 입력측에서 출력측으로 전달되는 에너지를 제어하는 기능을 수행하는데, PWM-IC(펄스폭 변조-집적회로), MOSFET(산화물-반도체 전계 효과 트랜지스터), 인덕터, 콘덴서, 저항 등으로 구성되어 있다. 방사선의 영향으로 DC/DC 컨버터의 PWM-IC 를 구성하는 비교기(comparator)와 연산증폭기(OP-Amp.) 등 전자소자의 열화 효과(radiation effects)가 발생되는데, PWM-IC 동작에서 SPICE 시뮬레이션과 실험을 통해 펄스의 상실, 펄스폭의 변화, 그리고 출력파형의 변화를 연구하는데 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.946-949
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• 2001

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of dc to dc PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of dc to dc PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype boost converter operating at 40kHz.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.169-173
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• 2001

In this paper, dc link ripple currents for three-phase ac/dc/ac PWM converters are ana lysed in a frequency domain. The expression of the harmonic currents is developed by using switching functions and exponential Fourier series expansion. The dc link ripple currents with regard to power factor and modulation index are investigated. In addition, the effect of the displacement angle between the switching periods of line-side converters and load-side inverters on the dc link ripple current is studied. The result of the dc link current analysis is helpful in specifying the dc link capacitor size and its lifetime estimation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.366-373
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• 2005

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.

• Journal of Power Electronics
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• 제1권2호
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• pp.71-77
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• 2001

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of DC to DC PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of DC to DB PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype converter operating at 40 kHz.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.384-390
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• 2012

This paper proposes a fault diagnosis method of the line-to-line voltage sensors in 3-phase AC/DC pulse width modulation (PWM) converters. The line-to-line voltage sensors are an essential device to obtain the information of the grid voltages for controlling the 3-phase AC/DC PWM converters. If the line-to-line voltage sensors are mismeasured by various faults, the voltage sensors can obtain wrong information of the grid voltage. It has an adverse effect on the control of the converter. Therefore, the converter causes the unbalance input AC current and the DC-link voltage ripple in the 3-phase AC/DC PWM converter. Hence, fast fault detection and fault tolerant control are needed. In this paper, the fault diagnosis method is proposed and verified through simulations and experiments.

• 전력전자학회논문지
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• 제21권6호
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• pp.530-537
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• 2016

This work deals with a switching method for minimizing overcurrent in a three-phase interleaved bidirectional DC-DC converter with frequency modulation. Generally, a three-phase interleaved DC-DC converter is used to reduce a current ripple component. The combined operation of three-phase and two-phase converters can significantly reduce the ripple component. However, the conventional PWM method cannot solve severe overcurrent during phase transfer or frequency variation for power control. To overcome this problem, this work proposes a new PWM switching method. A 3 kW DC-DC power converter is designed and implemented, and the converter is operated in discontinuous current mode with varying switching frequencies for power control. Simulation and experimental results show the validity of the proposed switching method. The proposed switching method can be widely used in the field of current ripple reduction for three-phase interleaved bidirectional DC-DC converters.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 연구회 합동 학술발표회 논문집
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• pp.28-32
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• 1998

This paper presents novel ZVZCS PWM DC-DC converters. The proposed soft-switching technique achieves ZVS and ZCS simultaneously at both turn-on and turn-off of the main switch and diode by using only one auxiliary switch. Also, the proposed soft-switching technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary circuit of the proposed topology is placed out the main power path and therefore, there are no voltage/current stresses on the main switch and diode. The operating principle of the proposed circuit is illustrated by a detailed study with the boost converter as an example. The validity of the proposed converter is verified by theoretical analysis, simulation and experiment results.

• Journal of Power Electronics
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• 제18권6호
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• pp.1634-1641
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• 2018

This study focuses on a high-performance direct active and reactive power controller design that is successfully applicable to three-phase pulse width modulation (PWM) AC/DC converters used in renewable distributed energy generation systems. The proposed controller can overcome the sluggish transient dynamic response of conventional controllers to rapid power command changes. Desired active and reactive powers can be thoroughly obtained at the end of each PWM period through a deadbeat solution. The proposed controller achieves an exact nonlinear cross-coupling decoupling of system power without using a predefined switching table or bang/bang hysteresis control. A graphical and analytical analysis that naturally leads to a control voltage vector selection is provided to confirm the finding. The proposed control strategy is evaluated on a 3 kW PWM AC/DC converter in the simulation and experiment.

• Journal of Power Electronics
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• 제9권2호
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• pp.156-163
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• 2009

In this paper a family of zero current transition PWM converters which employs a simple auxiliary circuit is introduced. This soft switched auxiliary circuit is only composed of a switch and a capacitor. The proposed converters are analyzed and various operating modes of the ZCT flyback converter are discussed. Design considerations are presented and the experimental results of the ZCT flyback converter laboratory prototype are illustrated. The experimental results confirm the validity of theoretical analysis.