• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.673-676
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• 2001

In this paper, the improved zero-voltage transition(ZVT) PWM boost converter using an inductor feedback technique is proposed. The improved circuit uses a low-voltage zener diode to reduce the turn-off witching loss of the auxiliary witch and EMI noise. Using this technique, soft-witching for the auxiliary switch is guaranted at wide line and load ranges and some of the energy circulating in the auxiliary circuit is fed to the load Since the active switches are turned on and off softly, the witching losses and EMI noise are reduced significantly and the higher efficiency of the system is achieved. In this paper, the modes of converter operation are explained and analyzed, design guidelines are given, and experimental results of 1kW, 100kHz prototype system are presented.

• Journal of Power Electronics
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• 제16권5호
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• pp.1689-1697
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• 2016

Continuous conduction mode (CCM) boost converters are commonly used in home appliances and various industries because of their simple topology and low input current ripples. However, these converters suffer from several disadvantages, such as hard switching of the active switch and reverse recovery problems of the output diode. These disadvantages increase voltage stresses across the switch and output diode and thus contribute to switching losses and electromagnetic interference. A new topology is presented in this work to improve the switching characteristics of CCM boost converters. Zero-current turn-on and zero-voltage turn-off are achieved for the active switches. The reverse-recovery current is reduced by soft turning-off the output diode. In addition, an input current sensorless control is applied to the proposed topology by pre-calculating the duty cycles of the active switches. Power factor correction is thus achieved with less effort than that required in the traditional method. Simulation and experimental results verify the soft-switching characteristics of the proposed topology and the effectiveness of the proposed input current sensorless control.

• 전력전자학회논문지
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• 제19권1호
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• pp.57-63
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• 2014

In this paper a bidirectional DC-DC converter is proposed for renewable energy systems, eco-friendly vehicles, energy storage systems, uninterruptible power supply(UPS) systems and battery test equipments. The two-stage bidirectional converter employing a fixed-frequency series loaded resonant converter is designed to be capable of operating under zero-current-switching turn on and turn off regardless of voltage and load variation, and hence its magnetic components and EMI filters can be optimized. And efficiencies and volumes of the two-stage bidirectional converters are compared according to configuration of isolated and non-isolated parts and a two-stage topology suitable for low voltage and high current applications is proposed. A 12kW(12V, 1000A) prototype of the proposed converter has been built and tested to verify the validity of the proposed operation.

• 전기전자학회논문지
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• 제12권2호
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• pp.110-117
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• 2008

본 연구는 전력용 스위칭 소자로 널리 활용되고 있는 IGBT(Insulated Gate Bipolar Transistor)소자로서 NPT(Non Punch Through) IGBT 구조에 기반 한 새로운 구조의 IGBT를 제안하였다. 제안된 구조는 기존 IGBT 구조의 P-베이스 영역 우측 부분에 N+를 도입함으로 N-드리프트 영역의 정공분포를 N+영역으로 밀집시켜 턴-오프 시 정공의 흐름을 개선, 기존 구조보다 더 빠른 턴-오프 시간과 더 낮은 순방향 전압강하를 갖는 구조이다. 또한 P+를 게이트 우측 하단에 형성함으로써 순방향 전압 강하 특성을 개선시키기 위해 도입한 캐리어 축적 층인 N+에 의해 발생하는 낮은 래치-업 특성과 낮은 항복 전압 특성을 개선시킨 구조이다. 시뮬레이션 결과 제한된 구조의 턴-오프와 순방향 전압강하는 기존 구조대비 각각 0.3us, 0.5V 향상된 특성을 보였다.

• 전기전자학회논문지
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• 제12권4호
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• pp.255-262
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• 2008

본 논문에서는 기존 IGBT의 구조적 한계로 인한 순방향 전압강하와 스위칭 손실간의 트레이드-오프 관계를 극복하고, 좀 더 우수한 전기적 특성을 갖는 새로운 구조의 nMOS 삽입형 IGBT를 제안하였다. 제안된 구조는 IGBT소자의 셀(Cell)과 셀 사이에 존재하는 폴리(poly) 게이트 영역에 nMOS를 형성시킨 구조로 N-드리프트 층으로의 전자, 정공의 주입효율을 증가시켜 기존 구조보다 더 낮은 온-저항과 빠른 스위칭 손실을 얻도록 설계된 구조이다. 시뮬레이션 결과 제안된 구조의 단일 소자인 경우 순방향 전압강하와 스위칭 특성은 각각 2.65V와 4.5us로, 기존 구조가 갖는 3.33V와 5us비해 약 26%의 감소된 순방향 전압강하와 10%의 낮은 스위칭 특성을 보였으며 래치-업 특성은 773A/$cm^2$로 기존 520A/$cm^2$보다 33%의 상승된 특성을 보였다.

• 전기전자학회논문지
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• 제14권1호
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• pp.55-64
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• 2010

본 논문에서는 기존 TIGBT의 구조적 한계로 인한 순방향 전압강하와 스위칭 손실간의 트레이드-오프 관계를 극복하고, 좀 더 우수한 전기적 특성을 갖는 새로운 구조의 pMOS 삽입형 트렌치 TIGBT를 제안하였다. 제안된 구조는 TIGBT소자의 셀(Cell)과 셀 사이에 존재하는 폴리(poly) 게이트 영역에 pMOS를 형성시킨 구조로 n-드리프트 층으로의 전자, 정공의 주입효율을 증가시켜 기존 구조보다 더 낮은 온-저항과 빠른 스위칭 손실을 얻도록 설계된 구조이다. 시뮬레이션 결과 제안된 구조의 단일 소자인 경우 순방향 전압강하와 스위칭 특성은 각각 1.67V와 3.1us로, 기존 구조가 갖는 2.25V와 3.4us비해 각각 약 25%의 감소된 순방향 전압강하와 약 9% 감소된 스위칭 특성을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.351-354
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• 2006

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system It needs both a DC-DC step-up converter and DC-AC inverter to be used in fuel cell generation system Therefor, this paper, consists of an isolated DC -DC converter to boost the fuel cell voltage 380[$V_{DC}$] and a PWM inverter with LC filter to convent the DC voltage to single phase 220[$V_{AC}$]. Expressly, a tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed high frequency isolated ZVZCS PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena Besides the efficiency of 93-97[%]is obtained over the wide output voltage regulation ranges and load variations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1207-1208
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• 2006

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system. It needs both a DC-DC step-up converter and DC-AC inverter to be used in fuel cell generation system. Therefor, this paper, consists of an isolated DC-DC converter to boost the fuel cell voltage 380[VDC] and a PWM inverter with LC filter to convent the DC voltage to single-phase 220[VAC]. Expressly, a tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed high frequency isolated ZVZCS PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of 93-97[%] is obtained over the wide output voltage regulation ranges and load variations.

• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.943-949
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• 2000

In this paper, the single and double heterostructure organic light-emitting devices(OLEDs) were fabricated. The single heterostructure OLED(TYPE 1) is consisted of TPD as a HTL(hole transfer layer) and Alq$_3$as an EML(emitting layer). The double heterostructure OLED(TYPE 2) is consisted of TPD as a HTL, Alq$_3$as an EML and PBD as an ETL(electron transfer layer). The another double heterostructure OLED(TYPE 3) is consisted of TPD as a HTL, PBD as an EML and Alq$_3$as an ETL. We obtained a strong green emission device with maximum EL emission wavelength 500nm in TYPE 3. When the applied voltage was 12V, the emission luminescence was 120.9cd/㎡. The chromaticity index of TYPE 3 was x=0.29, y=0.50. In the characteristic plot of current-voltage, TYPE 3 device was turned on at 6.9V. This voltage was a fairly low turn-on voltage. TYPE 1 and 2 device were turned on at 10V and 8.9V respectively. These types showed no good properties over that of TYPE 3.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.76-79
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• 1999

Low-hydrogenated DLC films were coated on the Mo-tip FEAs by 'layer-by-layer' process based on the plasma-enhanced CVD method. The hydrogen content in the DLC film deposited by the 'layer-by-layer' process was appeared to be remarkably lowered through SIMS analysis. Also, the low-hydrogenated DLC-coated Mo-tip FEA showed good potentiality for FED applications in terms of turn-on voltage, emission current, emission stability and light emitting uniformity.