• 전기전자학회논문지
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• 제14권3호
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• pp.250-255
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• 2010

본 논문에서는 DTMOS(Dynamic Threshold voltage MOSFET) 스위칭 소자를 사용한 인터리브 방식의 전원제어 장치(PMIC)를 제안하였다. 휴대기기에 필요한 높은 출력 전압과 낮은 출력 전압을 제공하기 위하여 벅-부스트 컨버터를 사용하였다. 또한, 높은 출력 전류에서 고 전력 효율을 얻기 위하여 PWM(Pulse Width Modulation) 제어 방식을 사용하였다. 낮은 온-저항을 갖는 DTMOS를 사용하여 도통 손실을 감소시켰으며 인터리브 방식을 사용하여 출력 리플을 감소시켰다. 1mA 이하의 대기모드에서도 높은 효율을 구현하기 위하여 LDO를 설계하였다.

• 조명전기설비학회논문지
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• 제18권6호
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• pp.128-135
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• 2004

본 논문은 자기부상열차용 전원의 문제점을 개선시키기 위해서 다중루프 제어기를 제시하였다. 제시된 제어기는 3개의 부분으로 구성되어 있다. 첫 번째는 입력전압의 변동에 대하여 보상할 수 있는 Feed Forward제어기이며 두 번째는 리액터 전류와 출력 전류의 차를 보상하며, 세 번째는 비례적분제어기를 사용하여 출력전압에 포함된 리플을 감소시키므로써, 안정화된 시스템을 구현하였다. 이 시스템의 특성을 확인하기 위해서 Matlab Simulink와 고성능 DSP소자인 TMS320F240을 이용하여 비교 분석하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제41권1호
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• pp.76-82
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• 2017

최근 전자제어엔진 및 전기추진선박이 도입된 이래, 배터리를 사용하는 비상 전력공급시스템에서 무정전 전원공급장치의 중요성이 강조되어왔다. 비상 전력공급시스템에서 양방향 컨버터는 중요한 구성요소이다. 본 연구에서는 개선된 DC-DC 양방향 컨버터의 토폴로지를 제시한다. 이것은 기존의 컨버터에 비해 전압변환율은 증가되고 스위치에 인가되는 전압 스트레스는 감소되는 장점을 지닌다. 제안된 컨버터의 성능을 확인하기 위해 소프트웨어 PSIM을 사용하여 시뮬레이션을 수행하였다. 이 컨버터의 변환율은 기존의 컨버터에 비해 승압모드에서 4배, 강압모드에서 1/4배 이었고 스위치에 걸리는 전압은 고압 측의 1/4배 이었다. 또한 블로킹 커패시터가 전하를 균등하게 분배하기 때문에 다른 추가 제어회로 없이 인터리브 모듈 사이에서 전하가 균등하게 분담된다는 것을 확인하였다.

• 한국전기전자재료학회논문지
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• 제13권9호
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• pp.729-734
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• 2000

Recently, Very Large Scale Integrated (VLSI) circuit & deep-submicron bulk Complementary Metal Oxide Semiconductor(CMOS) devices require gate electrode materials such as metal-silicide, Titanium-silicide for gate oxides. Many previous authors have researched the improvement sub-micron gate oxide quality. However, few have reported on the electrical quality and reliability on the ultra thin gate oxide. In this paper, at first, I recommand a novel shallow trench isolation structure to suppress the corner metal-oxide semiconductor field-effect transistor(MOSFET) inherent to shallow trench isolation for sub 0.1${\mu}{\textrm}{m}$ gate oxide. Different from using normal LOCOS technology deep-submicron CMOS devices using novel Shallow Trench Isolation(STI) technology have a unique"inverse narrow-channel effects"-when the channel width of the devices is scaled down, their threshold voltage is shrunk instead of increased as for the contribution of the channel edge current to the total channel current as the channel width is reduced. Secondly, Titanium silicide process clarified that fluorine contamination caused by the gate sidewall etching inhibits the silicidation reaction and accelerates agglomeration. To overcome these problems, a novel Two-step Deposited silicide(TDS) process has been developed. The key point of this process is the deposition and subsequent removal of titanium before silicidation. Based on the research, It is found that novel STI structure by the SEM, in addition to thermally stable silicide process was achieved. We also obtained the decrease threshold voltage value of the channel edge. resulting in the better improvement of the narrow channel effect. low sheet resistance and stress, and high threshold voltage. Besides, sheet resistance and stress value, rms(root mean square) by AFM were observed. On the electrical characteristics, low leakage current and trap density at the Si/SiO$_2$were confirmed by the high threshold voltage sub 0.1${\mu}{\textrm}{m}$ gate oxide.

• Journal of Power Electronics
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• 제16권6호
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• pp.2035-2044
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• 2016

In order to match the voltages between high voltage battery stacks and low voltage super-capacitors with a high conversion efficiency in hybrid energy sources electric vehicles (HESEVs), a high ratio bidirectional DC-DC converter with a synchronous rectification H-Bridge is proposed in this paper. The principles of high ratio step-down and step-up operations are analyzed. In terms of the bidirectional characteristic of the H-Bridge, the bidirectional synchronous rectification (SR) operation is presented without any extra hardware. Then the SR power switches can achieve zero voltage switching (ZVS) turn-on and turn-off during dead time, and the power conversion efficiency is improved compared to that of the diode rectification (DR) operation, as well as the utilization of power switches. Experimental results show that the proposed converter can operate bidirectionally in the wide ratio range of 3~10, when the low voltage continuously varies between 15V and 50V. The maximum efficiencies are 94.1% in the Buck mode, and 93.6% in the Boost mode. In addition, the corresponding largest efficiency variations between SR and DR operations are 4.8% and 3.4%. This converter is suitable for use as a power interface between the battery stacks and super-capacitors in HESEVs.

• 전기전자학회논문지
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• 제13권4호
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• pp.63-68
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• 2009

본 논문에서는 CCD 이미지 센서용 PMIC를 제안한다. CCD 이미지 센서는 온도에 민감하다. 일반적으로 낮은 효율을 갖는 PMIC에 의해 열이 발생된다. 발생된 열은 CCD 이미지 센서의 성능에 영향을 미치므로 높은 효율을 갖는 PMIC를 사용함으로써 최소화 시켜야 한다. 고효율의 PMIC개발을 위해 입력단은 동기식 step down DC-DC컨버터로 설계하였다. 제안한 PMIC의 입력범위는 5V~15V이고 PWM 제어방식을 사용하였다. PWM 제어회로는 삼각파 발생기, 밴드갭 기준 전압회로, 오차 증폭기, 비교기로 구성된다. 삼각파 발생기는 1.2MHz의 발진 주파수를 가지며, 비교기는 2단 연산 증폭기로 설계되었다. 오차 증폭기는 40dB의 DC gain과 $77^{\circ}$ 위상 여유를 갖도록 설계하였다. step down DC-DC 컨버터의 출력은 Charge pump의 입력으로 연결된다. Charge pump의 출력은 PMIC의 출력단인 LDO의 입력으로 연결된다. PWM 제어회로와 Charge pump 그리고 LDO로 구성된 PMIC는 15V, -7.5V, 5V, 3.3V의 출력전압을 갖는다. 제안한 PMIC는 0.35um 공정으로 설계하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.967_968
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• 2009

For lighting application, high-power LED nowadays is driven at 350mA and a sensing resistor is used to provide feedback for LED-current regulation. This method adds an IR drop at the output branch, and limits power efficiency as LED current is large and keeps increasing. In this paper, a power efficient LED-current sensing circuit is proposed. The circuit does not use any sensing resistor but extracts LED-current information from the output capacitor of the driver. Controlling the brightness of LEDs requires a driver that provides a constant, regulated current. In one case, the converter may need to step down the input voltage, and, in another, it may need to boost up the output voltage. These situations often arise in applications with wide-ranging ""dirty"" input power sources, such as automotive systems. And, the driver topology must be able to generate a large enough output voltage to forward bias the LEDs. So, to provide this requirements, 13W prototype Buck-Boost Converter is used.

• Journal of Power Electronics
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• 제14권6호
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• pp.1166-1177
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• 2014

A new type of topology with medium-frequency-transformer (MFT) isolation for medium voltage wind power generation systems is proposed in this paper. This type of converter is a high density power conversion system, with high performance features suitable for next generation wind power systems in either on-shore or off-shore applications. The proposed topology employs single-phase cascaded multi-level AC-AC converters on the grid side and three phase matrix converters on the generator side, which are interfaced by medium frequency transformers. This avoids DC-Link electrolytic capacitors and/or resonant L-C components in the power flow path thereby improving the power density and system reliability. Several configurations are given to fit different applications. The modulation and control strategy has been detailed. As two important part of the whole system, a novel single phase AC-AC converter topology with its reliable six-step switching technique and a novel symmetrical 11-segment modulation strategy for two stage matrix converter (TSMC) is proposed at the special situation of medium frequency chopping. The validity of the proposed concept has been verified by simulation results and experiment waveforms from a scaled down laboratory prototype.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권1호
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• pp.10-14
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• 2003

The occurrence of partial discharge (PD) in solid dielectrics is very harmful because it leads to the deterioration of insulation by electrical, chemical, and thermal reactions as a combined action of the discharged ions bombarding the surface and by the action of chemical compounds that are formed by the discharge. Consequently, if any defects are present in the solid insulation system, performance decreases until the system breaks down. Therefore, removing or suppressing the defect is very important. Voids are a typical defect in the solid insulation system and are very harmful because they deteriorate insulation. As a basic step, studying the properties of PD in voids is important because an accurate knowledge of these properties is required to estimate the deterioration of voids. In this paper, the correlation between the size of voids and internal PD is discussed as a function of the time of the applied voltage and its magnitude. Magnitude, repetition rate, average discharge power, and average discharge current of PD in specimens with large voids were found to be larger than the others in this experiment. The smaller specimens had voids when the magnitude and number of PDs were reduced.

• Journal of Power Electronics
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• 제17권3호
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• pp.601-609
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• 2017

Gallium nitride (GaN) power switching devices are promising candidates for high switching frequency and high efficiency power conversion due to their fast switching, low on-state resistance, and high-temperature operation capability. In order to facilitate the use of these new devices better, it is required to investigate the device characteristics and performance in detail preferably by comparing with various conventional silicon (Si) devices. This paper presents a comprehensive study of GaN high electron mobility transistor (HEMT) based non-isolated point-of-load (POL) synchronous buck converter operating at 2.7 MHz with a high step-down ratio (24 V to 3.3 V). The characteristics and performance of GaN HEMT and three different Si devices are analytically investigated and the optimal operating point for GaN HEMT is discussed. Zero-voltage switching (ZVS) is implemented to minimize switching loss in high switching frequency operation. The prototype circuit and experimental data support the validity of analytical and simulation results.