• 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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권6호
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• pp.336-341
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• 1999

In this paper a control method to compensate the fluctuation in source voltage by using reactive current is presented. When the source voltage is changed within $\pm$10[%] range, the unit power factor is carried out. Otherwise, the converter is controlled by variable power factor. By using above control, the converter input voltage is maintained constantly. And then it was certified by simulation with the ACSL and several experiments.

• Journal of Power Electronics
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• 제16권6호
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• pp.2005-2015
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• 2016

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.

• 전력전자학회논문지
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• 제13권5호
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• pp.352-359
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• 2008

본 논문에서는 왜곡된 전원전압 하에서 삼상 PWM 컨버터의 전류 보상 기법을 제안하였다. PWM 컨버터의 제어에 있어서 전원단 전압의 정확한 위상각 정보는 필수적이다. 동기좌표계 PLL 기법을 이용하여 고조파 전압이 포함되어 있는 전원단의 위상각을 검출하는 경우 전원 전압의 고조파로 인해 왜곡된 위상각을 얻게 된다. 이러한 왜곡된 위상각으로 컨버터를 제어하는 경우 입력 전류는 순수 정현파가 되지 않고 고조파가 포함된다. 본 논문에서는 왜곡된 전원단 전압 조건에 대해서도 입력 전류의 고조파를 IEEE Std. 519 규정인 5% 이내로 제한할 수 있도록 하는 전류 보상기법을 제안하였다. 시뮬레이션과 실험을 통하여 제안된 기법의 타당성을 검증하였다.

• Journal of Power Electronics
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• 제15권1호
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• pp.1-9
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• 2015

This study presents a novel transformer isolated parallel connected quasi Z-source (qZ-source) full-bridge DC-DC converter that uses a coupled inductor in both the qZ-source network and output filter inductor. Unlike traditional voltage-fed or current-fed converters, the proposed converter can be open- and short-circuited without damaging switching devices. Therefore, the desired buck and boost functions can be achieved and converter reliability can be significantly improved. All the bulky inductors in the qZ-source network and output filter can also be minimized with the proposed inductor structures. A 4 kW prototype DC-DC converter is built and tested to verify the performance of the proposed converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.428-430
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• 2007

Converter that is dc source equipment source's phase by reference control function that detect source's phase because should be done compulsorily use. Source's phase detect method there be method that use source's ac voltage directly by signal, and use methods that voltage detects status by PLL method and so on via point that '0' becomes usually. All above methods to detect phase are using, wrong action of phase detector converter's ailment or converter of burn can. Ths paper compares and examined usable phase detection method in source's frequency fluctuation presuming source's frequency using observer.

• 전기학회논문지
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• 제64권2호
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• pp.232-239
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• 2015

Faced with unbalanced grid operation mode, the high voltage direct current (HVDC) based on voltage source converter (VSC) can be properly controlled by a dual current control scheme. For the modular multilevel converter (MMC) controlling the AC side current is able to limit the arm current which flows along the IGBT of submodule (SM) to rated current. However the limitation of the arm current results in leaving the control range of active power at MMC confined to below the rated capacity. As a result, limiting the arm current causes the problem that the DC side voltage of the HVDC can not be controlled to the reference value since MMC HVDC adjusts the DC side voltage through the active power. In this paper, we propose the algorithm adjusting the active powers of both MMCs to resolve the problem. The back-to-back MMC HVDC applying the algorithm is modeled by PSCAD/EMTDC to verify the algorithm.

• 전기학회논문지
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• 제63권11호
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• pp.1588-1593
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• 2014

The scott transformer changes three-phase power to two single-phase power. However, this method causes unbalance and fluctuation of voltage by the change of electric railload. Recently, the AC railway system based on $3{\Phi}/1{\Phi}$ back-to-back (BTB) voltage source converter (VSC) has been proposed to solve these problems. Meanwhile, battery energy storage system (BESS) is used to compensate voltage instantaneously in power system. In this paper, BESS application to the AC railway system based on $3{\Phi}/1{\Phi}$ BTB VSC is suggested to compensate voltage instantaneously. The application effect is shown through simulation using MATLAB/SIMULINK.

• 전기의세계
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• 제23권4호
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• pp.60-65
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• 1974

This paper is to study on the pilot work of bi-directional S.C.R. power converter adopted by the method of diode-bridge type circuit. This apparatus acts as a converter when it is used in convering 3-phase a.c source to d.c output, and it can be used as an inverter which recovering surplus d.c power to a.c source when d.c load become active to cause the induced voltage higher than the presetted point of d.c output voltage. At the same time, its d.c voltage varies continuously in the presetted range of positive and/or negative polarity. As a result of test, the AC/DC bi-directional power converter represents maximum converting efficiency of 91% and power factor of 0.98. Furthermore, this converter also can be applied as a cycleconverter by varying the period of gate triggering signal.

• Journal of Power Electronics
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• 제9권6호
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• pp.835-844
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• 2009

In this paper a new buck-boost type DC-DC converter is presented. Its voltage gain is positive, all active elements operate under soft-switching condition independent of loading, magnetic isolation and self output short-circuit protection exist, and very fast dynamic operation is achievable by a simple bang-bang controller. This converter also exhibits appropriate PFC characteristics since its input current is inherently proportional to the source voltage. When the voltage source is off-line, it is sufficient to add an inductor after the rectifier, then near unity power factor is achievable. All essential guidelines to design the converter as a DC-DC and a PFC regulator are presented. Simulation and experimental results verify the developed theoretical analysis.