• Title, Summary, Keyword: DC-DC power conversion

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Dual Utility AC Line Voltage Operated Voltage Source and Soft Switching PWM DC-DC Converter with High Frequency Transformer Link for Arc Welding Equipment

  • Morimoto Keiki;Ahmed NabilA.;Lee Hyun-Woo;Nakaoka Mutsuo
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.4
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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.

A Study on a Performance Analysis of Direct-Conversion Receiver In Additive White Gaussian Noise Channel (AWGN 채널환경에서 Direct-Conversion 수신기의 성능분석에 관한 연구)

  • 조형래;김철성;박성진
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.668-675
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    • 2001
  • Recently, the performance of the commercial PCS(Personal Communication Service) system has been improved to the uppermost limit and ultimately the next generation mobile communication is to be realized by IMT-2000 (International Mobile Communication-2000) to provide multimedia services. Therefore, the new type receiving system is researched actively and one of the most important part in a receiver is direct conversion method. The direct conversion method is suitable for low power consumption, small size, MMIC, and low price, which is to be adopted to the next generation mobile communication systems. In this case, however, several problems occur due to DC-offset. The DC-offset suppresses amplification of the required signal because of the leakage signal of frequency synthesizer in the system. In this thesis, the removing method of DC-offset was considered. There are four removing techniques of DC-offset, which are AC-coupling, large capacitor, DC-feedback loop, and DC-free coding. Among these, the AC-coupling method is the most simplest method and the DC-feedback loop method has the best performance. Then, the performance of the AC-coupling method and DC-feedback loop method are evaluated by HP's ADS simulation tool. As a result, the AC-coupling method cannot be used to the digital communication systems due to data loss. On the other hand, it was confirmed that the DC-feedback loop method is suitable for the direct conversion receiver.

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The Economic Evaluation of Renewable Energy Penetration Based on Grid Parity According to the Ratio of DC Power Supply (Grid Parity를 고려한 DC 전원 공급율에 따른 신재생에너지 계통 연계의 경제성 평가)

  • Kim, Sung-Yul;Lee, Sung-Hun;Kim, Jin-O
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.1
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    • pp.16-21
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    • 2012
  • The growth in IT industry has brought a corresponding rise in the number of connected digital devices in the distribution network. These digital loads lead to AC to DC conversion losses in order to supply power to them. The more the renewable energies and plug-in electrical vehicles penetrated our lives, the more the electrical losses are caused by AC to DC conversion process. Hence, this paper suggests the methodology for evaluating the amount of power supplied according to the ratio of DC power supply and performs an economic analysis of DC distribution system considering grid parity. In here, the cost of carbon emission reduced by renewable energy is also concerned.

DC Link Switch Loss Analyses according to Circuit Structures of the Boost Converter for Photovoltaic Generation System (태양광 발전 시스템을 위한 부스트 컨버터의 회로 구성에 따른 직류측 스위치 손실 분석)

  • Lee, Seung-Yo
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.4
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    • pp.192-198
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    • 2012
  • Switch losses directly affect the efficiency of power conversion systems and those have big differences according to the power consumed by load systems and the structures of power conversion circuits. In this paper, analyses for switch losses in DC link converter are performed based on the circuit structures of the DC/DC converter in photovoltaic generation system whose output power is varied according to the amount of solar radiation, temperature and partial shade on the solar modules. Boost converter is adopted as a DC link converter topology of the photovoltaic generation system and the loss analyses for the switches used in the boost converters are performed according to the circuit structures. Analyses like the things performed in this paper will be a prerequisite to designing the photovoltaic generation system whose output power is changed according to the environmental variations.

Three-Phase PWM Inverter and Rectifier with Two-Switch Auxiliary Resonant DC Link Snubber-Assisted

  • Nagai Shinichiro;Sato Shinji;Matsumoto Takayuki
    • Journal of Power Electronics
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    • v.5 no.3
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    • pp.233-239
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    • 2005
  • In this paper, a new conceptual circuit configuration of a 3-phase voltage source, soft switching AC-DC-AC converter using an IGBT module, which has one ARCPL circuit and one ARDCL circuit, is presented. In actuality, the ARCPL circuit is applied in the 3-phase voltage source rectifier side, and the ARDCL circuit is in the inverter side. And more, each power semiconductor device has a novel clamp snubber circuit, which can save the power semiconductor device from voltage and current across each power device. The proposed soft switching circuits have only two active power semiconductor devices. These ARCPL and ARDCL circuits consist of fewer parts than the conventional soft switching circuit. Furthermore, the proposed 3-phase voltage source soft switching AC-DC-AC power conversion system needs no additional sensor for complete soft switching as compared with the conventional 3-phase voltage source AC-DC-AC power conversion system. In addition to this, these soft switching circuits operate only once in one sampling term. Therefore, the power conversion efficiency of the proposed AC-DC-AC converter system will get higher than a conventional soft switching converter system because of the reduced ARCPL and ARDCL circuit losses. The operation timing and terms for ARDCL and ARCPL circuits are calculated and controlled by the smoothing DC capacitor voltage and the output AC current. Using this control, the loss of the soft switching circuits are reduced owing to reduced resonant inductor current in ARCPL and ARDCL circuits as compared with the conventional controlled soft switching power conversion system. The operating performances of proposed soft switching AC-DC-AC converter treated here are evaluated on the basis of experimental results in a 50kVA setup in this paper. As a result of experiment on the 50kVA system, it was confirmed that the proposed circuit could reduce conduction noise below 10 MHz and improve the conversion efficiency from 88. 5% to 90.5%, when compared with the hard switching circuit.

Two-Switch Auxiliary Resonant DC Link Snubber-Assisted Three-Phase Soft Switching PWM Sinewave Power Conversion System with Minimized Commutation Power Losses

  • Nagai, Shinichiro;Sato, Shinji;Ahmed, Tarek;Nakaoka, Mutsuo
    • Journal of Power Electronics
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    • v.3 no.4
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    • pp.249-258
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    • 2003
  • This paper presents a high-efficient and cost effective three-phase AC/DC-DC/AC power conversion system with a single two-switch type active Auxiliary Resonant DC Link (ARDCL) snubber circuit, which can minimize the total power dissipation. The active ARDCL snubber circuit is proposed in this paper and its unique features are described. Its operation principle in steady-state is discussed for the three phase AC/DC-DC/AC converter, which is composed of PWM rectifier as power factor correction (PFC) converter, sinewave PWM inverter. In the presented power converter system not only three-phase AC/DC PWM rectifier but also three-phase DC/AC inverter can achieve the stable ZVS commutation for all the power semiconductor devices. It is proved that the proposed three-phase AC/DC-DC/AC converter system is more effective and acceptable than the previous from the cost viewpoint and high efficient consideration. In addition, the proposed two-switch type active auxiliary ARDCL snubber circuit can reduce the peak value of the resonant inductor injection current in order to maximize total system actual efficiency by using the improved DSP based control scheme. Moreover the proposed active auxiliary two-switch ARDCL snubber circuit has the merit so that there is no need to use any sensing devices to detect the voltage and current in the ARDCL sunbber circuit for realizing soft-switching operation. This three-phase AC/DC-DC/AC converter system developed for UPS can achieve the 1.8% higher efficiency and 20dB lower conduction noise than those of the conventional three-phase hard-switching PWM AC/DC-DC/AC converter system. It is proved that actual efficiency of the proposed three-phase AC/DC-DC/AC converter system operating under a condition of soft switching is 88.7% under 10kw output power.

Design and Fabrication of Rectenna for Microwave Wireless Power Transmission (마이크로파 무선전력전송을 위한 렉테나 설계와 구현)

  • Park, Jeong-Heum
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.6
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    • pp.43-48
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    • 2006
  • In this paper, the rectenna converting 2.45[GHz] microwave into DC power is designed and fabricated for wireless power transmission using microwave and the methode for impedance matching and tuning are proposed in order to maximize RF-DC conversion efficiency. The fabricated rectenna can be easily tuned by using a broad open stub and has the RF-DC conversion efficiency up to 59[%] when the 5[dBm] input power is applied. The 2.2[V], 1.5[mW] DC level, in the 1[m] distance between the transmitter and the receiver can be obtained and this value is avaliable in the small power digital system.

A high efficient PV system using series connection of DC-DC converter's output with photovoltaic panel (광전지 패널과 DC-DC 컨버터 출력의 직렬 접속을 이용한 고효율 PV 시스템)

  • Kim, Ho-Sung;Kim, Jong-Hyun;Min, Byung-Duk;Yoo, Dong-Wook;Hong, Ji-Tae;Lee, Dong-Gil;Kim, Hee-Je
    • Proceedings of the KIEE Conference
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    • pp.1146-1147
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    • 2008
  • PV Power Conditioning System (PCS) must have high conversion and low cost. Generally, PV PCS uses either a single converter or multilevel module integrated converter (MIC). Each of these approaches has both advantage and disadvantage. For a high conversion efficiency and low cost of PV module, this paper proposes series connection of module integrated DC-DC converter's output with PV panel. Output voltage of PV panel is connected to the output capacitor of flyback converter. Thus, converter's output voltage is added to the output voltage of PV panel. Isolated DC-DC converter generates only the difference voltage between the PV panel voltage and the required total output voltage. This method reduces power level of DC-DC converter and enhances the energy conversion efficiency compared with conventional DC-DC converter.

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A Study of the Three Port NPC based DAB Converter for the Bipolar DC Grid (양극성 직류 배전망에 적용 가능한 3포트 NPC 기반의 DAB 컨버터에 대한 연구)

  • Yun, Hyeok-Jin;Kim, Myoungho;Baek, Ju-Won;Kim, Ju-Yong;Kim, Hee-Je
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.4
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    • pp.336-344
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    • 2017
  • This paper presents the three-port DC-DC converter modeling and controller design procedure, which is part of the solid-state transformer (SST) to interface medium voltage AC grid to bipolar DC distribution network. Due to the high primary side DC link voltage, the proposed converter employs the three-level neutral point clamped (NPC) topology at the primary side and 2-two level half bridge circuits for each DC distribution network. For the proposed converter particular structure, this paper conducts modeling the three winding transformer and the power transfer between each port. A decoupling method is adopted to simplify the power transfer model. The voltage controller design procedure is presented. In addition, the output current sharing controller is employed for current balancing between the parallel-connected secondary output ports. The proposed circuit and controller performance are verified by experimental results using a 30 kW prototype SST system.

Active-Clamp AC-DC Converter with Direct Power Conversion (직접전력변환 방식을 이용한 능동 클램프 AC-DC 컨버터)

  • Cho, Yong-Won;Kwon, Bong-Hwan
    • The Transactions of the Korean Institute of Power Electronics
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    • v.17 no.3
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    • pp.230-237
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    • 2012
  • This paper proposes an active-clamp ac-dc converter with direct power conversion that has a simple structure and achieves high efficiency. The proposed converter is derived by integrating the step-down ac chopper and the output-voltage doubler. The proposed converter provides direct ac-dc conversion and dc output voltage without using any full-bridge diode rectifier. The step-down ac chopper using an active-clamp mechanism serves to clamp the voltage spike across the main switches and provides zero-voltage turn-on switching. The resonant-current path formed by the leakage inductance of the transformer and the resonant capacitor of the output-voltage doubler achieves the zero-current turn-off switching of the output diodes. The operation principle of the converter is analyzed and verified. A 500W prototype is implemented to show the performance of the proposed converter. The prototype provides maximum efficiency of 95.1% at the full load.