• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.114-115
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• 2004

인버터는 주로 커패시터 입력형 정류기를 사용하고 있다. 이로인해 인버터는 역률이 나쁘고 고조파가 발생하며 화학적, 열적 특성의 열화로 인버터 고장율을 증가시킨다. 따라서 평활용 커패시터를 제거하면 불완전한 특성을 갖는 커패시터로 인한 문제점을 해결할 수 있다. 그러나 다시 이로 인하여 발생되는 리플전압으로 인한 문제가 박생하게 된다. 본 연구에서는 이러한 리플을 순시추종 보상형 PWM 제어기를 사용하여 해결하므로 우수한 특성을 갖는 인버터 시스템을 설계할 수 있었다.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.23-25
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• 2009

전력용 커패시터는 전압 보상 및 부하에 필요한 무효전력을 전원측을 대신하여 공급함으로서 역률을 향상시킬 수 있으며, 리액터와 직렬로 연결할 경우 비선형 부하에서 발생하는 고조파 성분을 흡수하여 전압 고조파 왜형을 줄이고 전류고조파를 흡수하는 필터로도 사용이 가능하다. 그러나 수용가 부하가 일정하지 않고 변동하거나 선형부하와 비선형 부하가 존재할 경우 커패시터가 고조파의 홉수 등으로 인해 고장이 나는 경우가 많은 편이다. 그래서 본 연구에서는 현장에서 각 부하기기에 고조파를 줄이는 장치의 부착과 부착 전후 커패시터에 미치는 영향을 측정 분석하여 커패시터 규정과의 비교도 실시하였다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1422-1424
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• 2005

본 논문에서는 전원회로의 박형화에 장애가 되는 자기소자(인덕터/변압기)를 박형의 자기코어와 PCB 권선을 이용하여 박형으로 설계/제작하고 이를 역률보상회로와 서스테인 전원회로로 구성된 AC-PDP 전원회로에 적용한다. 이러한 역률보상회로와 서스테인 전원회로로 구성된 AC-PDP 전원회로를 박형자기소자, 박형커패시터 SMD소자를 이용하여 두께 30mm이하로 설계/제작하여 AC-PDP TV 시스템의 박형화 가능성을 제시한다. 또한 입력전압 90-260$V_{rms}$의 범위에서 역률개선 여부를 검증하고, 서스테인 전원회로의 부하변동에 따른 전체 AC-PDP 전원회로의 효율을 측정, 검증한다. 전원회로 각각의 구성요소에서 발생하는 전력손실을 분석하여 안정적인 AC-PDP 전원회로의 설계 가능성을 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.197-204
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• 2010

This paper proposes a new body-effect compensated switch configuration for low voltage and low distortion switched-capacitor (SC) applications. The proposed circuit allows rail-to-rail switching operation for low voltage SC circuits and has better total harmonic distortion than the conventional bootstrapped circuit by 19 dB. A 2-1 cascaded sigma-delta modulator is provided for performing the high-resolution analog-to-digital conversion on audio codec in a communication transceiver. An experimental prototype for a single-stage folded-cascode operational amplifier (opamp) and a 2-1 cascaded sigma-delta modulator has been implemented m a 0.25 micron double-poly, triple-metal standard CMOS process with 2.7 V of supply voltage. The 1% settling time of the opamp is measured to be 560 ns with load capacitance of 16 pF. The experimental testing of the sigma-delta modulator with bit-stream inspection and analog spectrum analyzing plot is performed. The die size is $1.9{\times}1.5\;mm$.

• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.35-45
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• 2022

In this paper, we modeled the devices used easily in PV system circuits. In addition, for full operation of the photovoltaic system, a complete operation system for the DC-DC buck-boost converter and the MPPT control system was modeled and simulated to confirm good operation. we were constructed an actual system with the same conditions in the simulation and experimented. The purpose is to confirm the stable power supply through the load leveling by presenting the PCS considering ESS of photovoltaic power generation. we will do study to apply hybrid capacitors that have high energy density to the same size compared to the EDLC to DVR. As a result, we proposed a single-phase 3 kW grid-connected solar power converter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.995-998
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• 2005

This paper proposes a new SoC (System-on-Chip)-based automatic compensation circuit (ACC) for 5GHz low noise amplifier (LNA). This circuit is extremely useful for today's RF IC (Radio Frequency Integrated Circuit) devices in a complete RF transceiver environment. The circuit contains RF BIST (Built-ln Self-Test) circuit, Capacitor Mirror Banks (CMB) and digital processing unit (DPU). The ACC automatically adjusts performance of 5GHz LNA by the processor in the SoC transceiver when the LNA goes out of the normal range of operation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.25-31
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• 2008

The field of induction motor is magnetized and demagnetized for each reversal of the current. This field component of the motor accounts for most of the reactive component of inductive load. Reactive power needs to sustain the electromagnetic field required for the induction motor to operate. Power factor of induction motor is usually low and power factor correction needs. Power factor becomes low by the effect of the reduction operation of load capacity. In most cases, Capacitor capacity for the power factor correction should be complied with the recommendation by the motor capacity. But Capacitor value for power factor correction can't change during the normal operation. In this paper, we analyzed characteristics of power and power factor changing by load fluctuation of low-voltage small size induction motor and show that lower power factor correction's parameter of existing recommendation should be revised by new value.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.335-342
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• 2000

A new control method for a single-phase active power filter, based on a load current estimation using a DC capacitor voltage of active power filter without sensing nonlinear load current, is proposed in this paper. Because the method proposed can remove the load current sensor in comparison with a conventional method sensing the load current and DC capacitor voltage together, it can make the active power filter easy installation, low cost, small size with no performance detriment. In addition, sample-hold technique and proportional control method is adopted to control the DC capacitor voltage and as no delay element such as LPF or PI control in the conventional method is used, the transient response is fast and good. Operation of a single-phase active power filter which consist of eight mode is explained according to utility voltage, compensation current and switch state, and compensation characteristics of active power filter using proposed method is verified by experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.205-212
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• 2004

In this paper the design of a 1-[KVA] fuel cell powered line-interactive UPS system employing modular (fuel cell & DC/DC converter) blocks is proposed. The proposed system employs the two fuel cell modules along with suitable DC/DC converters and these modules share the DC-Link of the DC/AC inverter. A supercapacitor module is also employed to compensate for the instantaneous power fluctuations and to overcome the slow dynamics of the fuel processor. The energy stored in the supercapacitor can also be utilized to handle the overload conditions for a short time period. Due to the absence of batteries, the system satisfies the demand for an environmentally friendly and dean source of the energy. A complete design example illustrating the amount of hydrogen storage required for 1hr power outage, and sizing of supercacpacitor for transient load demand is presented for a 1-[KVA] UPS.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.544-552
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• 2004

This paper deals with the hybrid active filter which can reduce the 11th/13th harmonics in AC network by using the single tuned filter. Since the proposed algorithm uses the detuning compensation capability of the filter, the output voltage of the proposed active power filter is changed according to the capacitance of capacitors, magnitude of harmonic current, resonance frequency and control mode. In this paper, the control characteristics and the design of hybrid active filter is investigated. A new hybrid active filter with new algorithm, which is an active filter with single tuned filter instead of double tuned filter, is proposed.