• Journal of Power Electronics
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• 제15권3호
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• pp.741-752
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• 2015

This study proposes a new solution for the parallel operation of microgrid inverters in terms of circuit topology and control structure. A combined three-phase four-wire inverter composed of three single-phase full-bridge circuits is adopted. Moreover, the control structure is based on adaptive three-order sliding-mode control and wireless load-sharing control. The significant contributions are as follows. 1) Adaptive sliding-mode control performance in inner voltage loop can effectively reject both voltage and load disturbances. 2) Virtual resistive-output-impedance loop is applied in intermediate loop to achieve excellent power-sharing accuracy, and load power can be shared proportionally to the power rating of the inverter when loads are unbalanced or nonlinear. 3) Transient droop terms are added to the conventional power outer loop to improve dynamic response and disturbance rejection performance. Finally, theoretical analysis and test results are presented to validate the effectiveness of the proposed control scheme.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.143-148
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• 2014

Conventional wireless power transfer methods based on coupled magnetic fields need a complex winding structure on the surface of the energy transfer and shows poor efficiency near metal objects due to the eddy current effect. In this study, to mitigate these problems, we investigate an electric field-coupled power transmission system, which is less prone to metal object problems and EMI. Because of the fundamental physical limit in the size of link capacitances, a half-bridge converter with an impedance matching transformer is proposed and the design procedure is derived to provide a soft-switching scheme. Hardware implementation shows that the proposed scheme with a pair of 10cm by 10cm copper plate can power a 1.4W USB FAN in a separation of 0.2mm by using insulating paper when driven by 227 kHz gate pulse.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5409-5415
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• 2012

압전 세라믹 액추에이터는 스프레이, 디스펜서, 밸브제어와 같은 다양한 산업제품들에 응용된다. 압전 세라믹 소자의 기계적인 변위의 크기는 인가 전압의 크기에 의해 정해지므로, 압전 세라믹 액추에이터 구동을 위해서는 고전압 전원장치와 함께 전력증폭기가 필요하다. 본 논문에서는 간단하고 크기가 작은 H-브리지 형태의 전력증폭기와 플라이백 고전압 스위칭 모드 전원장치를 개발하였다. H-브리지 형태의 전력증폭기는 펄스폭 변조를 이용하여 압전 세라믹 액추에이터에 대한 에너지 입력의 크기를 쉽게 조절할 수 있다는 장점이 있다.

• Journal of Power Electronics
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• 제15권5호
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• pp.1286-1294
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• 2015

Capacitor current feedback active damping is extensively used in grid-connected converters with an LCL filter. However, systems tends to become unstable when the digital control delay is taken into account, especially in low switching frequencies. This paper discusses this issue by deriving a discrete model with a digital control delay and by presenting the stable region of an active damping loop from high to low switching frequencies. In order to overcome the disadvantage of capacitor current feedback active damping, this paper proposes a modified approach using grid current and converter current for feedback. This can expand the stable region and provide sufficient active damping whether in high or low switching frequencies. By applying the modified approach, the active damping loop can be simplified from fourth-order into second-order, and the design of the grid current loop can be simplified. The modified approach can work well when the grid impedance varies. Both the active damping performance and the dynamic performance of the current loop are verified by simulations and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.220-221
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• 2006

This paper presents a single-phase parallel active power filter with an analog control circuit to eliminate for harmonic source currents generated by nonlinear loads. The proposed system removes the harmonic source currents by injecting a compensation current that is 180' out of phase with the load harmonic current. The detection of the load harmonics is realized by a simple new structure, referred to the Notch Filter with GIC (Generalized Impedance Converter), which has higher Q than existing harmonic detecters and a simpler structure. The compensation current is obtained using the proposed harmonic detection circuit, DC-Link voltage, and output current of the full-bridge inverter controlled current mode PWM controller. The operation of the proposed system is verified experimentally.

• 한국정보통신학회논문지
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• 제14권6호
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• pp.1505-1510
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• 2010

본 논문은 근육의 기능을 조절하는 신경말단에 전기적인 자극을 가하여 신경의 반응 정도를 측정하는 플랫폼 구현에 관한 연구로써, 전기 자극에 대한 신경반응이 가해지는 전류량, 가해지는 전류지속시간, 전극위치에 따른 반응을 측정하였다. 신격자극의 전극 위치는 표면말달 운동신경이면 어느 신경이든지 가능하고, 신격자극 양식에는 단순연축자극(Single Twitch Stimulation), 사연속자극(Train-of-four, TOF), 두 집단 발사자극(Double Burst Stimulation, DBS)이 있다. 임베디드 시스템기반으로 가기위한 저전력 MCU를 선정하고, 기본적인 신경자극반응 측정 센서의 민감도를 알아보기 위해 센서 인터페이스를 구성하여 반응정도를 측정해야 한다. 그리고 측정된 Data의 정확도를 높이기 위해 고성능의 AD Convertor 선정하여 플랫폼을 구현하였다.

• 센서학회지
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• 제13권6호
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• pp.417-423
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• 2004

In order to obtain wide-beam characteristics and variable resonant frequency of a ultrasonic transducer for the array source, an electrode of transverse mode piezoelectric vibrator is divided, and an electronic inductance is connected to the divided electrodes. The electronic inductance is made by GIC (General Impedance Converter) circuit. Because the GIC circuit is made of OP-Amps and other passive elements, the value of the inductance can be selected easily. As the results, the electronic inductance is variable in the range from 0.2 mH to 1.2 mH. Using the inductance, the resonance frequency of the transducer can be changed in the range from 73 kHz to 86 kHz. In the directivity of the transducer, it is confirmed that the beam width of the transducer is wider than $80^{\circ}$ at -3 dB in water.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.875-880
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• 2018

This paper proposes a novel combined compensation structure in the infrared receiver chip. For the infrared communication chip, the current-voltage (I-V) convert circuit is crucial and important. The circuit is composed by the transimpedance amplifier (TIA) and the combined compensation structures. The TIA converts the incited photons into photocurrent. In order to amplify the photocurrent and avoid the saturation, the TIA uses the combined compensation circuit. This novel compensation structure has the low frequency compensation and high frequency compensation circuit. The low frequency compensation circuit rejects the low frequency photocurrent in the ambient light preventing the saturation. The high frequency compensation circuit raises the high frequency input impedance preserving the sensitivity to the signal of interest. This circuit was implemented in a $0.6{\mu}m$ BiCMOS process. Simulation of the proposed circuit is carried out in the Cadence software, with the 3V power supply, it achieves a low frequency photocurrent rejection and the gain keeps 109dB ranging from 10nA to $300{\mu}A$. The test result fits the simulation and all the results exploit the validity of the circuit.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.589-599
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• 2014

On the basis of the traditional ZSI (Z-source inverter), this paper presents a ESL-${\Gamma}$-ZSI, which uses a unique ${\Gamma}$-shaped impedance network and an extended SL network for boosting its output voltage in addition to their usual voltage-buck behavior. The inverter can increase the boost factor through adjusting shoot-through duty ratio and increasing the number of inductors. Capacitor voltage stress of ESL-${\Gamma}$-ZSI is a constant when 1>D>0, and ESL-${\Gamma}$-ZSI has small inductor current stress. The working principle of ESL-${\Gamma}$-ZSI and comparison with the classical ZSI and SL- ZSI are analyzed in detail. The power loss comparison between ESL-${\Gamma}$-ZSI and Cuk converter is analyzed detailedly. Simulation and experimental results are given to demonstrate the operation features of the inverter.

• 전력전자학회논문지
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• 제19권4호
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• pp.357-363
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• 2014

A programmable smart charger compatible to various load conditions is proposed in this paper. Since the proposed smart charger is compatible to various mobile devices having different rated voltage and power, it is convenient for carrying and easy to standardize many kinds of battery chargers. Moreover, since it uses the input impedance and built-in PMIC (Power management IC) of the load system to recognize the connection state and specifications of load system, hardware changes of load system is not only hardly necessary but it also features no addition communication cable and easy implementation. To confirm the validity of the proposed charger, the theoretical analysis and experiment results from a prototype compatible to three load conditions 5V/1A, 5V/2A and 12V/1A are provided.