• Journal of Power Electronics
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• 제16권6호
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• pp.1991-2004
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• 2016

An LC filter is required to reduce the output current ripple in the auxiliary resonant snubber inverter (ARSI) for high-performance applications. However, if the traditional control method is used in the ARSI with LC filter, then unnecessary current flows in the auxiliary circuit. In addressing this problem, a novel load-adaptive control that fully uses the filter inductor current ripple to realize the soft-switching of the main switches is proposed. Compared with the traditional control implemented in the ARSI with LC filter, the proposed control can reduce the required auxiliary current, contributing to higher efficiency and DC-link voltage utilization. In this study, the detailed circuit operation in the light load mode (LLM) and the heavy load mode (HLM) considering the inductor current ripple is described. The characteristics of the improved ARSI are expressed mathematically. A prototype with 200 kHz switching frequency, 80 V DC voltage, and 8 A maximum output current was developed to verify the effectiveness of the improved ARSI. The proposed ARSI was found to successfully operate in the LLM and HLM, achieving zero-voltage switching (ZVS) of the main switches and zero-current switching (ZCS) of the auxiliary switches from zero load to full load. The DC-link voltage utilization of the proposed control is 0.758, which is 0.022 higher than that of the traditional control. The peak efficiency is 91.75% at 8 A output current for the proposed control, higher than 89.73% for the traditional control. Meanwhile, the carrier harmonics is reduced from -44 dB to -66 dB through the addition of the LC filter.

• 조명전기설비학회논문지
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• 제13권1호
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• pp.46-52
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• 1999

본 논문은 NPC 인버터의 구조를 위한 유도전동기 구동 시스템의 새로운 히스테리시스 전휴 제어기법을 제안하였다. 이러한 NPC 구조를 가지는 히스테리시스 전류제어 인버터의 구조는 각상의 인버터 출력전압을 제어하는 주 스위칭 소자와 주 스위치 OFF시에 출력전압을 0전위로 유지시키기 위한 보조 스위칭 소자로 구성된다. 이와 같이 제안된 HNPC (Hysteresis current controlled Neutral Point Clamped) 스위칭 기법은 1차, 2차 전류밴드를 가지며, 전압스위칭 신호는 1차 밴드와 실제전류의 비교 결과로서 발생하고, 2차 밴드와 실제전류의 비교 결과는 전압 스위칭 신호의 상위와 하위를 스위치의 동작을 결정하는 신호로서 동작한다. 이러한 스위칭의 결과로서 제안된 인버터 시스템의 출력 파형은 기존의 전류제어 방식과 비교하여 적은 고조파 성분의 함유특성을 가지고, 동일한 전류밴드 범위에서 낮은 스위칭 주파수를 가진다. 본 연구에서는 제안된 기법을 유도 전동기 구동 시스템에 적용하므로 이들 특성을 시뮬레이션을 통하여 고찰하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1920-1923
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• 1991

An online RF power measurement is needed for the full-bridged MOS-FET RF power inverter because the output current and/or voltage waveform is other than sinusoidal. In order to satisfy the requirement, the online measurement of the output power of this type of RF power inverter by the use of the PC-98 personal computer has been presented. The current and voltage waveforms are sensed by the digital oscilloscope probes so as to obtain the instantaeous power and they are entered into the PC98 personal computer so as to average the instantaneous powers. The RF power of up to 1 kw at 1 MHz measured for the power inverter at the output transformer. This method was confirmed to be applied to evaluate the load resistance change with temperature.

• 조명전기설비학회논문지
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• 제29권9호
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• pp.42-50
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• 2015

The Buck-Boost converter consisted of two switches is more expensive than the conventional Buck converter, because of the increase of the components. However, it can control the DC voltage depending on the requested load voltage without additional circuits, because it can control the voltage under the relatively wide range of the load. Additionally, it can control the output voltage constantly under the variation of the input voltage. In the paper two control loops consisted of current and voltage control are designed. When two controllers are operated at the same time the problem of the output voltage is occurred. Therefore, the solution of the output voltage problem is proposed. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype system rated at 1kVA.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1108-1113
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• 1992

In this paper, the high frequency twin resonant inverter using MOSFET is presented. The output control is excellent and the EMI noise is reduced, because the output appear as the vector sum of current in each unit inverter. The output voltage and the output current of the inverter are controlled by PLL. In this paper, the principle of the twin resonant method is described. And computer simulations and experimental results are shown.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.281-284
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• 1997

In this paper, the eddy current flow meter with 4-coil group is designed and made on the basis of theory, and its characteristics is considered through dry test flow experiments. The biggest output signal varied with wave form and frequency, and 900Hz in rectangular wave, 27.12kHz in sine wave. The conductivity is bigger, the output signal is bigger and has a linearity between both relation, and also The Magnetic Reynolds Number and output characteristics. The flow faster and the output singnal is bigger.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.389-392
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• 2001

In this paper, we have explained electrical characteristics of a step-down Rosen type piezoelectric transformer for AC-adapter. When the electric voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, then output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformer were measured under the various conditions of loads and frequencies. We measured resonant frequency from impedance curve. It was shown from experiments that output voltage has increased and resonant frequency has changed according to various resistor loads. Output current has changed inversely proportional to resistances.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1032-1034
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• 2001

As well known, a solar cell has an optimal operating point to be able to get the maximum power $P_{max}$. So, many $P_{max}$ tracking controllers using the line voltage of a solar cell have been popularly used. But it may vary depending on the miss match between the solar cell output and the load. In this paper, we investigate the possibilities of $P_{max}$ control using the current tracking controller and the output voltage and the output current instead of the solar cell output power. And we also examine about the optimal power converter using ZVCS step up and down chopper circuit to operate the solar cell at an optimal voltage using these variables. And then, we show some experimental results to confirm the successful operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.312-315
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• 1995

The base/gate drive suppression method proposed by Joshi and Bose is that which detects the output current polarity of the leg and, according to the polarity, suppresses the base/gate drive of one of the ore switching devices of the leg. This method has the merit that it does not have the conventional dead time problem, reduces the power loss of the driving circuit and others. But this method has difficulty in implementation. In this paper, a new base/gate drive suppression method by detecting not the output current polarity but the output voltage polarity is proposed. The proposed method is easier to implement than Joshi and Bose's method.

• Journal of Power Electronics
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• 제6권3호
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• pp.271-278
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• 2006

A new high efficiency zero-voltage and zero-current switching (ZVZCS) bidirectional DC/DC converter is proposed in this paper. The proposed converter consists of two symmetric half-bridge cells as the input and output stages. MOSFETs of input stage are turned-on in ZVS condition, and those of output stage are turned-off in ZCS condition. In addition, MOSFETs of input and output stages have low voltage stresses clamped to input and output voltage, respectively. Therefore, the proposed converter has high efficiency and high power density. The operational principles are analyzed and the advantages of the proposed converter are described. The 300W prototype of the proposed converter is implemented for 42V hybrid electric vehicle (HEV) application in order to verify the operational principles and advantages.