• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.376-378
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• 2008

A new family of single-phase Z-source ac-ac converter(SZAC) based on single-phase matrix converter (SPMC) is proposed in this paper. Compared to conventional Z-source ac-ac converter, the proposed SZAC has unique feature: providing a wide range of output ac voltage with buck/boost in-phase (maintaining phase angle) and buck/boost out-of-phase (reversing phase angle) operation. A new commutation strategy is used to eliminate voltage spikes on switches. The operating principle of the proposed SZAC is presented. Analysis and experimental results are also presented.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.98-104
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• 2012

This paper presents a novel transformer isolated parallel connected full-bridge dc-dc converter using recently developed trans-Z-source network. Unlike the traditional voltage -fed or current-fed converters, the proposed converter can be open- and short-circuited without damaging switching devices. Therefore, the desired buck and boost function can be achieved and the converter reliability can be greatly improved. A 6 kW prototype dc-dc converter is built and tested to verify performances of the proposed converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.275-276
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• 2013

In this paper, we proposed the Z-source four-switch three-phase rectifier. As we know, the conventional Four-Switch Three-Phase Rectifier(FSTPR) has advantages of the lower cost and less complex switching control. However, The conventional FSTPR can only either perform buck or boost operation, it can only attain the buck-boost operation by adding another DC-DC converter. In addition, besides its narrow output voltage region, distortion of the input current is serious either. Thus, we proposed the Z-source FSTPR which has buck-boost function and better input current waveform by applying the Z-impedance network to the conventional FSTPR. The validity of the proposed system was confirmed by experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.350-352
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• 1996

A Hight Efficiency Quasi-Parallel Resonant DC-Link Inverter which shows highly improved PWM capability, low loss characteristic and low voltage stress is presented. A method to minimize freewheeling interval, which is able to largely decrease DC-link operation losses and to steadily guarantee soft switching in the wide operation region is proposed. Analysis and simple experiments were performed to verify validity of the proposed inverter topology.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.694-700
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• 1998

A novel zero-voltage-transition (ZVT) isolated PWM boost converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[8]. A simple auxiliary circuit which includes only one active switch provides zero-voltage-switching (ZVS) condition to all semiconductor devices. (Two active switches are required for the previous ZVT converter) This leads to reduced cost and simplified control circuit comparing to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 kW, 100 KHz laboratory prototype.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.855-860
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• 1998

This paper presents a new structure for a piezoelectric transformer, operating in thickness extensional vibration mode. Modified $PbTiO_3$ family ceramics were used for the piezoelectric transformer, because it was a material with large anisotropy between elecromechanical coupling factors $K_t$ and $K_p$ . The size of piezoelectric transformer was 20mn long, 20mm wide and 3.1mm thick. The second harmonic resonant frequency of thickness extensional vibration mode was 0.72MHz at loading resistance 100[$\omega$], And Voltage gin of piezoelectric ceramics showed 0.53 at resonant frequency of sencond thickness extensional vibration mode.

• 대한전자공학회논문지SD
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• 제45권8호
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• pp.44-47
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• 2008

본 논문에서는 UWB PLL charge pump 의 충/방전 전류오차를 최소화하기 위한 회로를 제안하였다. Common-gate 와 Common-source 증폭기를 추가한 피드백 전압 조정기를 구성하여 높은 응답성을 가지는 charge pump를 설계하였다. 제안한 회로는 넓은 동작 영역을 갖으며, 낮은 전원 전압으로도 뛰어난 성능을 보인다. 본 회로는 1.2V 공급 전압과 IBM 0.13um CMOS 공정으로 집적되었다. 설계의 효율성을 평가하기 위해 참고 논문의 다른 회로와 성능을 대조하였다.

• 전기학회논문지
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• 제65권1호
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• pp.88-96
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• 2016

In this paper, the GaN FET based phase-shift full-bridge dc-dc converter design is implemented. Switch characteristics of GaN FET were analyzed in detail by comparing state-of-the-art Si MOSFET. Owing to the low conduction resistance and parasitic capacitance, it is expected to GaN FET based power conversion system has improved performance. However, GaN FET is vulnerable to electric interference due to the relatively low threshold voltage and fast switching transient. Therefore, it is necessary to consider PCB layout to design GaN FET based power system because PCB layout is the main reason of stray inductance. To reduce the electric noise, gate voltage of GaN FET is analyzed according to operation mode of phase-shift full-bridge dc-dc converter. Two 600W phase-shifted full-bridge dc-dc converter are designed based on the result to evaluate effects of stray inductance.

• 센서학회지
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• 제26권4호
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• pp.223-227
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• 2017

Conventional CMOS image sensors (CISs) have a trade-off relationship between dynamic range and sensitivity. In addition, their sensitivity is determined by the photodiode capacitance. In this paper, CISs that consist of dual-sensitivity photodiodes in a unit pixel are proposed for achieving wide dynamic ranges. In the proposed CIS, signal charges are generated in the dual photodiodes during integration, and these generated signal charges are accumulated in the floating-diffusion node. The signal charges generated in the high-sensitivity photodiodes are transferred to the input of the comparator through an additional source follower, and the signal voltages converted by the source follower are compared with a reference voltage in the comparator. The output voltage of the comparator determines which photodiode is selected. Therefore, the proposed CIS composed of dual-sensitivity photodiodes extends the dynamic range according to the intensity of light. A $94{\times}150$ pixel array image sensor was designed using a conventional $0.18{\mu}m$ CMOS process and its performance was simulated.

• 전력전자학회논문지
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• 제27권6호
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• pp.515-525
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• 2022

The wireless power transfer (WPT) charging system for AGV depends highly on the coupling conditions due to air gap variation. To attain stable output power with high transfer efficiency under various coupling conditions, a single-stage, DC-DC converter that operates with robustness to changes in air gaps is proposed for the WPT system. The proposed converter is capable of soft switching under the set input voltage (V_in: 380 V_DC), load conditions (0-1 kW), and air gap changes (30-70 mm). In addition, a wide output voltage range (Vo: 39-54 V_DC) can be controlled by varying the link voltage due to the phase control at a fixed switching frequency. Experimental results are verified using a prototype of a 1 kW wireless power charging system.