• 대한전기학회논문지
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• 제45권1호
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• pp.54-59
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• 1996

As the current shape of SRM is of pulse type and changed by the motor parameters and drive conditions, the influences on the drive efficiency by control method are more than other types of motors. In this paper, a proper excitation condition to drive a SRM with high efficiency is proposed and tested. It is derived from the conditions that the phase current of a SRM is to be flat-topped at various drive. The saturation effect of magnetic circuit is accounted for more accurate analysis. Experimental tests are executed to verify the proposed excitation method. This drive system is easy to commutate and also advantageous in reducing torque ripple. (author). 6 refs., 10 figs., 1 tab.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.393-398
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• 2006

This paper classifies driving technologies for AMOLEDs by the driving TFT conditions in pixels. A saturation region operation type driving TFT circuit provides good stability of OLED because of constant current drive. However, complicated compensation circuits are necessary to avoid effect of the TFT characteristics deviation. On the other hand, a linear region operation type driving TFT circuit provides better uniformity of the display image and lower power consumption. However, the stability of OLED is critical because of constant voltage drive.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.644-652
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• 2016

This paper presents an improved single-stage ac-dc LED-drive flyback converter using the transformer-coupled lossless (TCL) snubber. The proposed converter is derived from the integration of a full-bridge diode rectifier and a conventional flyback converter with a simple TCL snubber. The TCL snubber circuit is composed of only two diodes, a capacitor, and a transformer-coupled auxiliary winding. The TCL snubber limits the surge voltage of the switch and regenerates the energy stored in the leakage inductance of the transformer. Also, the switch of the proposed converter is turned on at a minimum voltage using a formed resonant circuit. Thus, the proposed converter achieves high efficiency. The proposed converter utilizes only one general power factor correction (PFC) control IC as its controller and performs both PFC and output power regulation, simultaneously. Therefore, the proposed converter provides a simple structure and an economic implementation and achieves a high power factor without the need for any separate PFC circuit. In this paper, the operational principle of the proposed converter is explained in detail and the design guideline of the proposed converter is briefly shown. Experimental results for a 40-W prototype are shown to validate the performance of the proposed converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.231-233
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• 1991

This paper discribes a study on the switching character of MOS-GTO and the design of gate drive circuit. Chopping power supply converter, synchronious and asyncronious motor speed adjustment, inverter, etc., needs low drive energy "high frequency" switches. To fulfill these need, switches must have rapid switching time and insulated gate control. MOS-GTO structure is well suited to these constraints. The power switch is serial installation of a GTO thyrister and a MOS Transistor. The gate of the GTO is linked to positive pole of the cascode structure via a MOS high voltage transistor and ground via a transient absorber diode. This high performance MOS-GTO assembly considerably increases the strength which facilitate the drive of GTO thyristers.

• 전력전자학회논문지
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• 제3권3호
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• pp.222-230
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• 1998

본 논문에서는 스너버 회로를 사용하지 않고 턴-온시 역회복 전류의 영향과 턴-오프 시 구동되는 IGBT에 발생하는 과전압을 제한할 수 있는 새로운 IGBT 게이트 구동회로를 제안한다. 제안하는 턴-온 게이트 구동기법은 턴-온 지연 시간을 증가시키지 않고 게이트-에이터 전압이 문턱전압 이상이 되면 IGBT의 입력 커패시턴스를 증가시킴으로써 게이트-에이터 전압의 증가율을 감소시키는 특징을 갖는다. 제안하는 턴-오프 게이트 구동기법은 전류의 크기에 따라 과전압을 제한하여 단락사고와 같은 대전류가 흐르는 경우 더욱 효과적으로 과전압을 제한하는 특징을 가진다. 또한, 여러 가지 조건에서 실험을 수행하여 제안한 IGBT 게이트 구동회로의 타당성을 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.346-349
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• 1996

In application of high power IGBT PWM inverters, the treatable power range is considerably limited due to the overvoltage caused by the stray inductance components within the power circuit. This paper proposes a new gate drive circuit for IGBTs which can actively suppress the overvoltage across the driven IGBT at turn-off and the overvoltage across the opposite IGBT at turn-on while preserving the most simple and reliable power circuit. The turn-off driving scheme has adaptive feature to the amplitude of collector current, so that the overvoltage is limited much effectively at the larger collector current. The turn-on scheme is to decrease the rising rate of the collector current by increasing input capacitance during turn-on transient when the gate-emitter voltage is greater than threshold voltage. The experimental results under various normal and fault conditions prove the effectiveness of the proposed circuit.

• 전기학회논문지
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• 제62권8호
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• pp.1095-1100
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• 2013

Piezo devices have large power density and simple structure compared with conventional electrical motors. Thus they can generate larger forces than the conventional actuators with small size. Their resopnses to commands are also very fast and thus the bandwidths are very wide. Thus the piezo devices are expected to be used widely in the future for actuating devices requiring fast response and large actuating force with small size. However, the piezo actuators need high voltage with high driving current due to their large capacitive property. In this paper, proposed is a simple method to drive piezo devices using voltage inversion circuit with coli inductance. The coil inductance carries the charges in the piezo device to the opposite side, inverting the polarity of the applied voltage, thus saving the power to drive the device with AC voltages. Experiments with real circuit demonstrates that the proposed scheme can improve the energy efficiency very much.

• Journal of Power Electronics
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• 제18권1호
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• pp.300-308
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• 2018

An online estimation method for wireless power transfer (WPT) systems is presented without using any measurement of the secondary side or the load. This parameter estimation method can be applied with a controlling strategy that removes both the receiving terminal controller and the wireless communication. This improves the reliability of the system while reducing its costs and size. In a wireless power transfer system with an LCCL impedance matching circuit under a rectifier load, the actual load value, voltage/current and mutual inductance can be reflected through reflected impedance measuring at the primary side. The proposed method can calculate the phase angle tangent value of the secondary loop circuit impedance via the reflected impedance, which is unrelated to the mutual inductance. Then the load value can be determined based on the relationships between the load value and the secondary loop impedance. After that, the mutual inductance and transfer efficiency can be computed. According to the primary side voltage and current, the load voltage and current can also be detected in real-time. Experiments have verified that high estimation accuracy can be achieved with the proposed method. A single-controller based on the proposed parameter estimation method is established to achieve constant current control over a WPT system.

• 대한전자공학회논문지SD
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• 제46권12호
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• pp.58-65
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• 2009

본 논문에서는 캐패시터로 상승 시간과 하강 시간을 조절하고 슈미트 트리거의 스위칭 전압을 이용한 데드 타임 회로를 갖는 고전압 구동 IC (High Voltage Gate Driver IC)를 설계하였다. 설계된 고전압 구동 IC는 기존 회로와 비교하여 온도에 따 른 데드 타임 변동을 약 52% 줄여 하프브리지 컨버터의 효율을 증대시켰으며 캐패시터 값에 따라 가변적인 데드 타임을 가진다. 또한 숏-펄스 (short-pulse) 생성회로를 추가하여 상단 레벨 쉬프트 (High side part Level shifter)에서 발생하는 전력소모를 기존의 회로에 비해 52% 감소 시켰고, UVLO를 추가하여 시스템의 오동작을 방지하여 시스템의 안정도를 향상시켰다. 제안한 회로를 검증하기 위해 Cadence의 Spectre을 이용하여 시뮬레이션 하였고 1.0um 공정을 이용하였다.

• Journal of Power Electronics
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• 제14권2호
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• pp.217-225
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• 2014

This paper deals with the optimization of the driving techniques for the ZVT synchronous buck converter proposed in [1]. Two new gate drive circuits are proposed to allow this converter to operate by only one control signal as a 12V voltage regulator module (VRM). Voltage-driven method is applied for the synchronous rectifier. In addition, the control signal drives the main and auxiliary switches by one driving circuit. Both of the circuits are supplied by the input voltage. As a result, no supply voltage is required. This approach decreases both the complexity and cost in converter hardware implementation and is suitable for practical applications. In addition, the proposed SR driving scheme can also be used for many high frequency resonant converters and some high frequency discontinuous current mode PWM circuits. The ZVT synchronous buck converter with new gate drive circuits is analyzed and the presented experimental results confirm the theoretical analysis.