• Journal of Power Electronics
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• 제14권2호
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• pp.203-216
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• 2014

In the conventional dc-dc converter, a pair of additional diode and the adjacent passive component capacitor/inductor can be added to the circuit with an X-shape connection, which generates a family of new topologies. The novel circuits, also called diode-assisted dc-dc converter, enhance the voltage boost/buck capability and have a great potential for high step-up/step-down power conversions. This paper mainly investigates and compares conventional dc-dc converter and diode-assisted dc-dc converter in wide range power conversion from the aspects of silicon devices, passive components requirements, electro-magnetic interference (EMI) and efficiency. Then, a comprehensive comparison example of a high step-up power conversion system was carried out. The two kinds of boost dc-dc converters operate under the same operation conditions. Mathematical analysis and experiment results verify that diode-assisted dc-dc converters are very promising for simultaneous high efficiency and high step-up/step-down power conversion in distributed power supply systems.

• 한국태양에너지학회 논문집
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• 제36권5호
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• pp.63-71
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• 2016

Installed PV module in field is affected by shading caused by various field environmental factors. Bypass diodes are installed in PV module for preventing a power loss and degradation of PV module by shading. But, Bypass diode is easily damaged by surge voltage and has often initial a defect. This paper propose the electric characteristic variation and the power prediction of PV module with damaged bypass diode. Firstly, the resistance for normal bypass diode and damaged bypass diode of resistance was measured by changing the current. When the current increases, the resistance of normal bypass diode is almost constant but the resistance of damaged bypass diode increases. Next, To estimate power of PV module by damaged bypass diode, the equation for the current is derived using solar cell equivalent circuit. Finally, the derived equation was simulated by using MatLab tools, was verified by comparing experimental data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.424.2-424.2
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• 2016

Solar cell converts light energy to electric energy. But a solar cell generates low power, PV module is fabricated by connected in series with dozens of solar cell. Owing to solar cell connected in series, power of PV module is influenced by shading or mismatch power of solar cells. To prevent power loss of PV module by shading or mismatch current, Bypass diodes are installed in PV module. Bypass diode operating reverse voltage by shading or mismatch power of solar cells bypass mismatch current. However, bypass diode in module exposed outdoor is easily damaged by surge voltage. In this paper, we confirm characteristics variation of PV module with damaged bypass diode. As a result, power of PV module with damaged bypass diode is reduced and Temperature of that is increased.

• 전기학회논문지P
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• 제63권4호
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• pp.361-367
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• 2014

This paper is related to a new solar power conditioner for a built-in step-up chopper function. In the first step-up chopper proposed solar PV power conditioner for mutually connected in series with the input voltage of the bypass diodes are respectively connected to the positive terminal should install the mutual boosting chopper diode connected in series with the boost chopper switching element between the two power supply and at the same time the first and the second was connected to a second diode and a resonance inductor and a snubber capacitor in series with each other. And the common connection point between the bypass diode and the step-up chopper and the step-up chopper diode common connection point of the switching elements of the input voltage was set to the boost inductor for storing energy. In addition, between the step-up chopper and the step-up chopper diode and a switching element of a joint connection point of the first auxiliary diode and the second common connection point of the auxiliary diode was provided, the resonance capacitor. Between the step-up chopper and the step-up chopper diode and a switching element of a joint connection point and the common connection point of the resonance inductor snubber capacitor and connecting the third secondary diode, between two power supply lines is characterized by configuring the DC link capacitor bus lines in parallel. Therefore, it is possible to suppress the switching loss through, DC link bus lines, as well as there could seek miniaturization and weight reduction of the power conditioner itself by using a common capacitor of the non-polar non-polar electrolytic capacitor having a capacitor, the service life of the circuit can be extended and it is possible to greatly reduce the loss can be greatly improve the reliability of the product and the operation of the product itself.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.192-195
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• 2001

In this report, we firstly have investigated the electrical characteristics of silicon carbide (SiC) schottky barrier diode and compared the characteristics to those of conventional Si diode through simulation and experiment. Secondly we have investigated the influence of two kinds of diodes to the power conversion circuit of the systems. From the investigation results it is verified that SiC schottky barrier diode is more superior to Si diode in thermal and reverse recovery, characteristics, which are the important factors in the size reduction and higher reliability of the systems. Finally though the experiment applied to PFC(Power Factor Correction) circuits, we precisely verified excellency to thermal characteristic of SiC schottky barrier diode any other diode.

• 한국전자파학회논문지
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• 제14권6호
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• pp.625-629
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• 2003

GaAs PIN 다이오드를 이용하여 저손실 고출력 MMIC 리미터를 설계하고 제작하였다. 고전력 수용 능력을 증가시키기 위하여 새로운 GaAs PIN 다이오드 에피구조를 제안하였다. 2종류의 리미터 회로를 설계하고 그리미팅 전력을 측정하였다. 측정결과에서 리미팅 전력은 설계회로 토폴로지에 따라 달라졌다. 제작된 2단 리미터의 리미팅 전력은 14 ㎓에서 각각 17 ㏈m과 23 ㏈m으로 측정되었다.

• 전기전자학회논문지
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• 제19권1호
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• pp.94-100
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• 2015

본 논문에서는 U-MOSFET 내부의 기생 body 다이오드(PN diode)를 쇼트키 body 다이오드(Schottky body diode)로 대체한 50V급 전력 U-MOSFET을 제안하였다. 쇼트키 다이오드는 PN 다이오드와 비교 시, 역 회복 손실(reverse recovery loss)을 감소시킬 수 있는 장점을 가지고 있다. 따라서 전력 MOSFET의 기생 body 다이오드를 쇼트키 body 다이오드를 대신함으로써 역 회복 손실을 최소화 할 수 있다. 제안된 쇼트키 body 다이오드(Schottky body diode) U-MOSFET(SU-MOS)를 conventional U-MOSFET(CU-MOS)와 전기적 특성을 비교한 결과, 전달(transfer) 및 출력(output)특성, 항복(breakdown)전압 등 정적(static) 특성의 변화 없이 감소된 역 회복 손실을 얻을 수 있었다. 즉, 쇼트키 다이오드의 폭(width)이 $0.2{\mu}m$, 쇼트키 장벽 높이(Schottky barrier height)가 0.8eV일 때 첨두 역전류(peak reverse current)는 21.09%, 역 회복 시간(reverse recovery time)은 7.68% 감소하였고, 성능지수(figure of merit(FOM))는 35% 향상되었다. 제안된 소자의 특성은 Synopsys사의 Sentaurus TCAD를 사용하여 분석되었다.

• 한국태양에너지학회 논문집
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• 제35권4호
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• pp.67-75
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• 2015

PV module is conventionally connected in series with some solar cell to adjust the output of module. Some bypass diodes in module are installed to prevent module from hot spot and mismatch power loss. However, bypass diode in module exposed outdoor is easily damaged by surge voltage. In this paper, we study the thermal and electrical characteristics change of module with damaged bypass diode to easily find module with damaged bypass diode in photovoltaic system consisting of many modules. Firstly, the temperature change of bypass diode is measured according to forward and reverse bias current flowing through bypass diode. The maximum surface temperature of damaged bypass diode applied reverse bias is higher than that of normal bypass diode despite flowing equal current. Also, the output change of module with and without damaged bypass diode is observed. The output of module with damaged bypass diode is proportionally reduced by the total number of connected solar cells per one bypass diode. Lastly, the distribution temperature of module with damaged bypass diode is confirmed by IR camera. Temperature of all solar cells connected with damaged bypass diode rises and even hot spot of some solar cells is observed. We confirm that damaged bypass diodes in module lead to power drop of module, temperature rise of module and temperature rise of bypass diode. Those results are used to find module with a damaged bypass diode in system.

• 한국광학회지
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• 제21권6호
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• pp.254-258
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• 2010

타원형 모양의 모드 형태를 갖는 펄스형 레이저 다이오드 (laser diode)의 펄스 형태를 유지하면서 단일 모드 및 Gaussian 형태로 광 모드 변환을 유도하고 광출력을 증폭할 수 있는 기술에 대해서 연구하였다. 실험에서 사용한 펼스형 레이저 다이오드의 구경이 가로는 $300{\mu}m$이며, 세로는 $2{\mu}m$이고 출력은 $1.1mW/cm^2$이다. 렌즈형 광섬유를 사용하여 광결합을 유도하여 단일 모드 및 Gaussian 형태의 출력으로 변환시켰다. 그러나, 다중모드의 펄스형 레이저 다이오드의 출력을 단일모드 렌즈형 광섬유에 결합시키면 출력이 급격하게 감소한다. 따라서 master oscillator power amplifier (MOPA) 기반의 광증폭 기술을 이용하여 레이저 다이오드의 광출력을 증폭시켰다. 증폭 후에도 펄스 성질은 그대로 유지되었고, MOPA구조를 지나 증폭된 광 출력은 $29mW/cm^2$로 측정되었다.

• 한국군사과학기술학회지
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• 제10권4호
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• pp.152-159
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• 2007

In this paper, a new design technique on the LRF which is useful for low power laser and a CBDA(Cummulative Binary Detection Algorithm) is proposed. The LD(Laser Diode) and Si-APD(Silicon Avalanche Photo Diode) are used for saving a power. In order to prove the detection range, the Si-APD binary data are accumulated before the range computation and the range finding algorithm. A prototype of the proposed DLRF(Diode Laser Range Finder) system was made and tested. An experimental result shows that the DLRF system have the same detection range using a less power(almost 1/32) than an usual military LRF. The proposed DLRF can be applied to the Unmanned Vehicles, Robot and Future Combat System of a tiny size and a low power LRF.