• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.89-96
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• 2004

High-linearity voltage-controlled current sources (VCCSs) circuits for wide voltage-controlled oscillator and automatic gain control are proposed. The VCCS consists of emitter follower for voltage input, two common-base amplifier which their emitter connected for current output, and current mirror which connected the two amplifier for large output current. The VCCS used only five transistors and a resistor without an extra bias circuit. Simulation results show that the VCCS has current output range from 0㎃ to 300㎃ over the control voltage range from 1V to 4.8V at supply voltage 5V. The linearity error of output current has less than 1.4% over the current range from 0A to 300㎃.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.16-28
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• 2012

This paper proposes a quasi Z-source converter(QZSC) with a diode-capacitor output filter to improve the output DC voltage boost ability. The proposed converter has the same quasi Z-source network topology compared with the conventional converter. But the proposed method is adopted a diode-capacitor filter as its output filter, since the conventional method is used an inductor-capacitor as its output filter. Under the condition of the same input-output DC voltage, the proposed method has more lower shoot-through duty ratio than the conventional method. Also, because the proposed converter has same voltage boost factor under lower shoot-through duty ratio compared with the conventional converter, the proposed converter can be operated with the lower capacitor voltage of Z-source network and the lower input current. To confirm the validity of the proposed method, PSIM simulation and a DSP based experiment were performed to acquire the output DC voltage 120[V] under the input DC voltage 80[V]. And the capacitor voltage and inductor current in Z-source network, the output voltage of each converter were compared and discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.6
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• pp.1596-1603
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• 1996

A single body type of fiber-optic current and voltae sensor using a rare earth doped YIG and a bismuth silicon oxide single crystsl is proposed, which is used for simultaneous measurement of the AC electric current and AC electric voltage over the trasmission lines. Experimental results showed that the fiber-optic current sensor has the maximum 7.5% error within the current range of 0A to 400A, and the fiber-optic voltage sensor has the maximum 0.87% error within the current range of 0V to 400V. The output waveforms of proposed fiber-optic sensor system has a good agreement with output waveforms of conductor current and voltage. Experimental results proved that the output of fiber-optic current sensor is not affected by the electric voltage applied to the fiber-optic voltage sensor, and also, that the output of fiber-optic voltage sensor is not affected by the electric current applied to the fiber-optic current sensor.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1436-1439
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• 2005

A novel current-type data driver for active matrix organic light emitting diode (AMOLED) is proposed for current uniformity enhancement among its output channels. New architecture is composed of shadow DACs that precharge output stages, a single-real DAC that correct the output level to a real target current level and output stages that operate in 3 states of sampling, correcting and driving. Simulation results show that the proposed driving method and circuits improve the current uniformity among output channels of a current-type driver IC.

• Journal of Power Electronics
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• v.13 no.1
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• pp.20-30
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• 2013

This paper presents a soft switching DC/DC converter for high voltage application. The interleaved pulse-width modulation (PWM) scheme is used to reduce the ripple current at the output capacitor and the size of output inductors. Two converter cells are connected in series at the high voltage side to reduce the voltage stresses of the active switches. Thus, the voltage stress of each switch is clamped at one half of the input voltage. On the other hand, the output sides of two converter cells are connected in parallel to achieve the load current sharing and reduce the current stress of output inductors. In each converter cell, a half-bridge converter with the asymmetrical PWM scheme is adopted to control power switches and to regulate the output voltage at a desired voltage level. Based on the resonant behavior by the output capacitance of power switches and the transformer leakage inductance, active switches can be turned on at zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. The current doubler rectifier is used at the secondary side to partially cancel ripple current. Therefore, the root-mean-square (rms) current at output capacitor is reduced. The proposed converter can be applied for high input voltage applications such as a three-phase 380V utility system. Finally, experiments based on a laboratory prototype with 960W (24V/40A) rated power are provided to demonstrate the performance of proposed converter.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.11
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• pp.48-56
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• 2011

Novel class-A bipolar current conveyor($CCII{\pm}$) with differential current output and its application to output current controllable CCII+ for electronic tuning systems are designed. The $CCII{\pm}$ is consists of conventional CCII+ and complementary cross current sources. The CCII+ with controllable the output current consists of the $CCII{\pm}$ and a current gain amplifier with single-ended current output. The simulation result shows that the $CCII{\pm}$ has current input impedance of $1.9{\Omega}$ and a good linearity for voltage and current follower. The proposed CCII+ has 3-dB cutoff frequency of 10MHz for the range over bias control current $100{\mu}A$ to 10mA. The range of output current control is four decade. The power dissipation of the CCII+ is 4.5mW at supply voltage of ${\pm}2.5V$.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.215-218
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• 2001

In conventional three-phase rectifiers, it was necessary to use a transformer to obtain low output voltage. In this paper, we propose a new three-phase rectifiers circuit that achieves low voltage by using a very simple circuit configuration that does not have a transformer and does not need any complex control. We also describe the operation principle of the proposed circuit, and derive a theoretical formula for its current waveform. On the basis of this formula it also explores the theoretical input/output current characteristics, theoretical current amplification factor, and theoretical output voltage characteristics of these theoretical values with experimentally obtained input/output current characteristics, current amplification factor, and output voltage characteristics, allowed us to confirm the soundness of our theoretical analyses.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.30-41
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• 1996

Current Source(CS) PWM converter is appropriate for the magnet power supply system which requests high power and high precision current control. Input and output filters should be installed to eliminate the current or voltage harmonics caused by the PWM switching for the CS PWM converter. But the input/output filters limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicated. In this paper, systematic and simple filter design method which considers not only the harmonic attenuation but also the total system good transfer function characteristics in the dc filter. The simulated and experimental results verify the proposed theory. (author). refs., figs., tabs.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.242-243
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• 2012

In this paper, 200 W power supply for LED driver has been designed, analyzed, simulated and tested. Input AC voltage of 100VAC-240VAC was converted to DC voltage by high power factor converter. Output voltage was controlled, and output current was controlled by constant current when output current was reached to LED maximum rated current. By simulation and experimental test, voltage and current control and high power factor characteristics are verified.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.208-216
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• 2018

In this paper, an LLC resonant converter employing two coupled inductors on the secondary side of the converter is proposed. The conventional LLC converter exhibits serious power loss during secondary winding of the transformer because of generation of tremendous output current ripples. To overcome this problem, an LLC resonant converter with a current doubler as a rectifying circuit was recently proposed. However, the current-doubler rectifying circuit requires coupled inductors with a high coupling ratio to retain the designed resonance characteristics. Therefore, an additional hardware filter is required at the output stage to address large output current ripples. Additional design procedures are also necessary because the inductance component of the added filter affects the designed resonant network. To solve this issue, an LLC resonant converter employing two coupled inductors is proposed in this paper. Mathematical analysis shows that the proposed secondary-side current-doubler circuit does not affect the designed resonance characteristics. The operating principles and theoretical analyses are proven through a simulation and experiments with a 54 V/28 A prototype.