• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.196-197
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• 2006

In this study, low temperature sintering multilayer piezoelectric transformer for DC-DC converter were manufactured using (PbCaSr)Ti(MnSb)$O_3$ ceramics and thin their electrical properties were investigated according to the vanation of frequency and load resistance. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value m the vicinity of 1.3MHz and increased according to the increase of load resistance. When the output impedance coincided with the load resistance, the piezoelectric transformer showed the temperature rise of about $21^{\circ}C$ under the output power of 6W.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.677-681
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• 2005

This Paper presents a 6 pulse shift operation control mode of current-source-inverter to make improvement of efficiency and to reduce the frequency of inverter switching for photovoltaic generation system using PWM current-source-inverter. This system is connected solar cell energy directly without using a storage cell. The proposed circuit can maintain maximum voltage of photovoltaic generation of take advantage of six Buck-Boost converter and a full-bridge inverter determines the polarity of AC output. That is controlled by using digital signal processor TMS320F2812 for operation about a 6 pulse shift operation control of current-source-inverter, and it is verified through the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1239-1241
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• 2004

In this paper, electronic ballast with Interleaved Boost Cell is presented. The proposed topology is based on a single-stage ballast which combines a boost converter and a half-bridge series resonant inverter High power factor and low THD(reduction of current ripple) are achieved by using the boost semi-stage operating in discontinuous conduction mode, and inverter semi-stage operated above resonant frequency to provide zero voltage switching is employed to ballast the fluorescent lamp. The experimental results from the ballast system with fluorescent lamps have demonstrated the feasibility of the proposed electronic ballast.

• Transactions on Electrical and Electronic Materials
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• 제1권3호
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• pp.1-5
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• 2000

This paper presents a new sort of multilayer piezoelectric ceramic transformer for switching regulation power supplies. This piezoelectric transformer operate in the second thickness resonant vibration mode. Accordingly its resonant frequency is higher than 1 NHz, Because output power is low if input and output part of transformer are consisted of single layer, this research suggests a new method, which is consisted of both input and output part of transformer have 2-layered piezoelectric ceramics, The size of transformer is 20 mm in width and length, and 1.4 mm in thickness, respectively, To design a high efficient switching circuit of the transformer, internal circuit parameters were measured and then weve calculated a parameter of inductor nd capacitor to design a driving circuit, Weve used a MISFET and its driver circuit modified a calp oscillator circuit as the primary switching circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.781-783
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• 1993

The GTO model is based on the Ebers-Moll equation extened to include the three-junction devices and a detailed description of the implementation of the model equation as well as defferent tests are discussed. Problems to be considered for the snubber design, such as voltage spike reduction, maximum GTO anode current, and switching power, were discussed using the calculation model. The macro model is very useful for simulation of GTO circuit and high power circuit switch in high frequency and complex structure.

• 전력전자학회논문지
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• 제27권1호
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• pp.26-32
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• 2022

This paper proposes a power system that includes a 120k W fuel cell DC-DC converter (FDC) and 30 kW bidirectional DC-DC converter (BHDC) for a 150 kW fuel-cell vehicle. With a high DC link voltage of 800 V, the efficiency and power density of the power electronic components are improved. Through the modular design of FDC and BHDC, electric components are shared, resulting in reduced mass production costs. The switching frequency of 30 kHz of full SiC devices and optimal design of coupled inductor reduce the volume, achieving a power density of 8.3 kW/L. Furthermore, a synergetic operation strategy using variable limiter control of FDC and BHDC was proposed to efficiently operate the fuel cell vehicle considering the fuel cell stack efficiency according to the load. Finally, the performance of the prototype was verified by Highway Fuel Economy Driving Schedule testing, EMI test, and the linked operation between FDC and BHDC. The full load efficiencies of the FDC and BHDC prototypes are 98.47% and 98.74%, respectively.

• 한국정보전자통신기술학회논문지
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• 제15권5호
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• pp.335-342
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• 2022

본 논문에서는 오디오 애플리케이션을 위한 단일 비트 3차 피드포워드 델타 시그마 변조기를 제안한다. 제안된 변조기는 저전압 및 저전력 애플리케이션을 위한 클래스-C 인버터를 기반으로 한다. 고정밀 요구 사항을 위해 레귤레이티드 캐스코드 구조의 클래스-C 인버터는 DC 이득을 증가시키고 저전압 서브쓰레스홀드 증폭기 역할을 한다. 제안된 클래스-C 인버터 기반 변조기는 180nm CMOS 공정으로 설계 및 시뮬레이션되었다. 성능 손실이 없으면서 낮은 공급 전압 호환성을 가지도록 제안된 클래스-C 인버터 기반 스위치드 커패시터 변조기는 높은 전력 효율을 달성하였다. 본 설계는 20kHz의 신호 대역폭 및 4MHz의 샘플링 주파수에서 동작시켜 93.9dB의 SNDR, 108dB의 SNR, 102dB의 SFDR 및 102dB의 DR를 달성하면서 0.8V 전원 전압에서 280μW의 전력 소비만 사용한다.

• International Journal of Contents
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• 제2권1호
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• pp.29-33
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• 2006

The common-source low noise amplifier(LNA) with inductive degeneration using a genetic algorithm is designed and tested for a down converter in an industrial, scientific and medical (ISM) band application and a wireless broadband internet service (WiBro). The genetic algorithm optimizes the reflection coefficients to be well matched the input and output ports between multistage transistor amplifiers, and it generates low voltage standing wave ratio as well as gain flatness of the amplifier. The stability and the gain flatness of the LNA have been improved by combining the matching circuits and the series feedback microstrip lines with inductive degeneration at common-source port. In the frequency range of ISM band and WiBro application operating at $2.3GHz{\sim}2.5GHz$, the measured power gain and maximum voltage standing wave ratio (VSWR) of the LNA are $41{\pm}0.5dB$ and 1.3, and the noise figure of the LNA is lower than 0.85dB. The above results are agreed well with the theoretical values of the amplifiers.

• 한국정보통신학회논문지
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• 제18권9호
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• pp.2176-2182
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• 2014

이 논문에서는 기존의 위상고정루프에 전원 잡음 제거 회로를 추가한 위상고정 루프 회로를 제안한다. 제안한 구조는 주파수 전압 변환기를 변형한 전원 잡음 제거 회로를 사용하여 임의의 전원 잡음에 대해 보상하여 동작한다. 전원 잡음 제거 회로를 사용하여 전원 잡음에 의해 발생하는 지터의 크기를 1/3로 줄였다. 제안한 위상 고정 루프는 0.18um CMOS 공정을 사용 하여 HSPICE 시뮬레이션을 통해 예측되는 결과를 검증하였다.

• Journal of Power Electronics
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• 제14권6호
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• pp.1100-1108
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• 2014

Modular multilevel converters (MMCs) have emerged as the most promising topology for high and medium voltage applications for the coming years. However, one particular negative characteristic of MMCs is the existence of circulating current, which contains a dc component and a series of low-frequency even-order ac harmonics. If not suppressed, these ac harmonics will distort the arm currents, increase the power loses, and cause higher current stresses on the semiconductor devices. Repetitive control (RC) is well known due to its distinctive capabilities in tracking periodic signals and eliminating periodic errors. In this paper, a novel circulating current control scheme base on RC is proposed to effectively track the dc component and to restrain the low-frequency ac harmonics. The integrating function is inherently embedded in the RC controller. Therefore, the proposed circulating current control only parallels the RC controller with a proportional controller. Thus, conflicts between the RC controller and the traditional proportional integral (PI) controller can be avoided. The design methodologies of the RC controller and a stability analysis are also introduced. The validity of the proposed circulating current control approach has been verified by simulation and experimental results based on a three-phase MMC downscaled prototype.