• 전력전자학회논문지
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• 제26권3호
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• pp.176-182
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• 2021

This research proposes a high-frequency circuit that can accurately predict the differential mode noise of single-phase inverters at the circuit design stage. Proposed single-phase inverter high frequency circuit in the work is a form in which harmonic impedance components are added to the basic single-phase inverter circuit configuration. For accurate noise prediction, parasitic components present in each part of the differential noise path were extracted. Impedance was extracted using a network analyzer and Q3D in the measurement range of 150 kHz to 30 MHz. A high-frequency circuit model was completed by applying the measured values. Simulations and experiments were conducted to confirm the validity of the high-frequency circuit. As a result, we were able to predict the resonance point of the differential mode voltage extracted as an experimental value with a high-frequency circuit model within an approximately 10% error. Through this outcome, we could verify that differential mode noise can be accurately predicted using the proposed model of the high-frequency circuit without a separate test bench for noise measurement.

• 한국자기학회지
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• 제26권4호
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• pp.137-141
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• 2016

전력의 효율적인 사용과 에너지 절감을 위한 비접촉 전류측정에 대한 요구가 커지고 있다. 본 연구에서는 무선 비접촉 측정을 가능하게 하는 2개의 결합코일과 전류의 인가에 의해서 인덕턴스가 변화하는 센서코일을 이용한 공진회로를 구성함으로써, 인가되는 전류의 크기에 따라 공진주파수가 변화하는 것을 이용한 비접촉 전류센서를 제안한다. 센서코일의 인덕턴스는 외부에 자석을 부착함으로써 부여되는 바이어스 자계에 의해서 자계(전류)의 크기뿐 아니라 방향을 판단할 수 있었다. 본 연구에서 구성한 비접촉 전류측정장치를 이용하여서 -3~+3 A의 전류를 측정하였을 때 18 V의 출력전압변화를 얻을 수 있었으나, 전류에 대한 출력특성은 선형적이지 않았다. 본 연구에서 제안하는 비접촉 전류측정방법(장치)를 보다 현실화시키기 위해서, 향후 출력신호의 선형화와 분해능의 엄밀한 검토가 필요하다.

• 한국전자파학회논문지
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• 제25권12호
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• pp.1300-1305
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• 2014

근접장 마이크로파 현미경의 핵심 부품인 H-형태 소형 개구를 가진 도파관 탐침에 대해 등가회로를 표현하고 해석하였다. 파장에 비해 작은 사각형 또는 원형의 소형 개구는 유도성 성분인데, 여기에 리지 구조를 부착하는 것은 용량성 성분을 연결하여 이로 인해 투과 공진을 일으키는 것으로 볼 수 있다. 이러한 해석을 입증하기 위해 리지가 있는 소형 개구에서 용량 성분에 해당되는 리지 부분을 분리하여 대략 반파장 떨어진 지점에 세워 두고 구한 등가회로적 표현에 의한 계산 결과와 전자파 해석에 의한 계산 결과와 비교하여 거의 일치된 모습을 확인하였다. 또한, 도파관 탐침을 제작하여 반사손실을 측정하고, 계산 결과의 정확성을 확인하여 이론의 타당성을 검증하였다.

• 조명전기설비학회논문지
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• 제23권11호
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• pp.22-27
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• 2009

This paper presents a two-paralleled four quadrant DC chopper type PWM power conversion circuit in order to generate a gradient magnetic field in the Magnetic Resonance Imaging (MRI) system. This circuit has 8-IGBTs at their inputs/outputs to realize further high-power density, high speed current tracking control, and to get a low switching ripple amplitude in a controlled current in the Gradient Coils (GCs). Moreover, the power conversion circuit has to realize quick rise/fall response characteristics in proportion to various target currents in GCs. It is proposed in this paper that a unique control scheme can achieve the above objective DSP-based control system realize a high control facility and accuracy. It is proved that the new control system will greatly enlarge the diagnostic target and improve the image quality of MRI.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1324-1326
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• 2000

This paper proposes a Current-Fed Push Pull type DC-DC converter using LCCC Resonant circuit and Zero Voltage Switching function to reduce turn on and off loss at the switching instants. This paper have the advantage which is able to operating safely in load short, because of DC reactor is connected with resonance reactor in order to supply a fixed current with low ripple from DC Power supply. The capacitor ($C_1$, $C_2$) connected in switch are common using as resonance capacitor and ZVS capacitor. The analysis of the proposed Current-Fed Push Pull type DC-DC converter is generally described by using normalized parameter, and we have evaluated characteristic values which is needed to design a circuit. We confirm a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment using MOSFET as switching devices.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.127-132
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• 2001

In this paper, transmitted sound reduction performance of smart panels is studied according to different piezoelectric materials with piezoelectric shunt damping. Peizo-damping is implemented by using a newly proposed tuning method. This method is based on electrical impedance model and maximizing the dissipated energy at the shunt circuit. By measuring the electrical impedance at the piezoelectric patch bonded on a structure, an equivalent electrical model is constructed near the system resonance frequency. After shunting elements are connected to the equivalent circuit, the shunt parameters are optimally searched based on the criterion of maximizing the dissipated energy at the shunt circuit. Transmitted sound reduction performance is compared according to different piezoelectric materials with peizo-damping. Two piezoelectric materials are selected: PZT-5 and QuickPack IDE actuator. When resonant shunt circuit is considered, the use of PZT-5 exhibited the good sound reduction performance.

• 한국초전도ㆍ저온공학회논문지
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• 제18권2호
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• pp.37-41
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• 2016

This paper presents the developed quench analysis code and protection circuit design for a superconducting magnet system of 28GHz electron cyclotron resonance (ECR) ion source. The superconducting magnet is composed of a hexapole magnet and four solenoid magnets located outside of the hexapole one. All magnets are wound with NbTi composite wire and impregnated by epoxy. By using the developed characteristic analysis code, the normal zone resistance, decaying current and temperature rising can be estimated during quench. Also, the stored magnetic energy is successfully consumed from the series resistor of the designed protection circuit. The analytical results are compared with the experimental results to verify the developed quench analysis code and protection circuit.

• 전자공학회논문지A
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• 제33A권4호
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• pp.78-83
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• 1996

A timing recovery circuit of 10 Gbit/s optical receiver is described. The circuit consists of a passive NRZ-to-PRZ circuit, a dielectric resonator filter (DRF) and a narrow band amplifier, which for the first time adopted a temperature compensation technique using the tempareature characteristics of DR. The experimental results showed an output clock phase variation of less than ${\pm}$6 degree over the operating temperature range form 0$^{\circ}C$ to 75$^{\circ}C$ and measured maximum rms jitters of less than 2 phs with the resonance detunings of up to ${\pm}$10 MHz. These experimental results show that the circuit is a suitable for 10 Gbit/s lightwave transmission system.

• Journal of Information Display
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• 제2권4호
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• pp.63-67
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• 2001

The switching power loss due to the panel capacitance during sustain period in AC PDP driving system can be minimized by using the energy recovery circuits. We proposed a new energy recovery circuit, SER1 (Seoul national univ. Energy Recovery circuit 1st). The experimental results of its application to a 42-inch surface discharge type AC PDP showed superior performance of SER1 in energy recovery efficiency and low distortion voltage waveform. Energy recovery efficiency of SER1 was measured up to 92.3 %, and the power dissipation during the sustain period was reduced by 15.2 W in 2000 pulse/frame compared with serial LC resonance energy recovery circuit.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.470-477
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• 2002

Possibility of passive piezoelectric damping based on a new shunting parameter estimation method is studied using finite element analysis. The adopted tuning method is based electrical impedance that is found at piezoelectric device and the optimal criterion for maximizing dissipated energy at the shunt circuit. Full three dimensional finite element model is used for piezoelectric devices with cantilever plate structure and shunt electronic circuit is taken into account in the model. Electrical impedance is calculated at the piezoelectric device, which represents the structural behavior in terms of electrical field, and equivalent electrical circuit parameters for the first mode are extracted using PRAP (Piezoelectric Resonance Analysis Program). After the shunt circuit is connected to the equivalent circuit for the first mode, the shunt parameters are optimally decided based on the maximizing dissipated energy criterion. Since this tuning method is based on electrical impedance calculated at piezoelectric device, multi-mode passive piezoelectric damping can be implemented for arbitrary shaped structures.