• 전력전자학회논문지
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• 제19권2호
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• pp.133-138
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• 2014

This paper proposes a low power-loss averaging current mode control using a resistor and bypass switch. Generally, current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. An analog-circuited bypass driver is implemented and used along with an average-circuit mode controller. The bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 50[W] prototype average current mode boost converter has been implemented for the experimental verification.

• Korean Chemical Engineering Research
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• 제52권2호
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• pp.182-186
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• 2014

두 종류의 집전체(BP, bipolar plate)를 사용하여 바나듐 레독스-흐름 전지(V-RFB, vanadium redox-flow battery)의 성능을 평가하였다. V-RFB의 성능평가는 $60mA/cm^2$의 전류밀도에서 진행하였다. A 집전체를 사용한 V-RFB의 기전력(SOC 100%에서의 OVC)은 1.47V, B 집전체를 사용한 V-RFB의 기전력은 1.54V를 나타냈다. A 집전체를 사용한 V-RFB의 셀 저항은 충전시에 $4.44{\sim}5.00{\Omega}{\cdot}cm^2$을, 방전시에 $3.28{\sim}3.75{\Omega}{\cdot}cm^2$를 보였으며, B 집전체를 사용한 V-RFB의 셀 저항은 충전시에 $4.19{\sim}4.42{\Omega}{\cdot}cm^2$, 방전시에 $4.71{\sim}5.49{\Omega}{\cdot}cm^2$를 나타냈다. 각 집전체를 사용한 V-RFB의 성능은 5회 충방전 실험을 진행하여 평가하였다. A 집전체를 사용한 V-RFB는 평균 전류효율 93.1%, 평균 전압효율 76.8%, 평균 에너지효율 71.4%를 나타냈으며, B 집전체를 사용한 V-RFB는 평균 전류효율 96.4%, 평균 전압효율 73.6%, 평균 에너지효율 71.0%를 나타냈다.

• Journal of Power Electronics
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• 제14권1호
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• pp.40-47
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• 2014

An average current mode control scheme that consistently offers good dynamic performance for LLC series resonant DC-to-DC converters irrespective of the changes in the operational conditions is presented in this paper. The proposed control scheme employs current feedback from the resonant tank circuit through an integrator-type compensation amplifier to improve the dynamic performance and enhance the noise immunity and reliability of the feedback controller. Design guidelines are provided for both current feedback and voltage feedback compensation. The performance of the new control scheme is demonstrated through an experimental 150 W converter operating with 340 V to 390 V input voltage to provide a 24 V output voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.539-541
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• 1994

The average current mode control of zero current switched series resonant converter is proposed. The conventional current controllers such as bang bang current controller and predictive current cantroller have some demerits like current offset and complexity. In this paper, the proposed current control technique are conventional current control techniques are comparatively studied. By the proposed control technique. the current cantroller can be simplely implemented without current offset.

• Journal of Power Electronics
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• 제9권6호
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• pp.903-910
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• 2009

In this paper, a digital average current mode control using diode current sensing technique is proposed. Although the conventional inductor current sensing technique is widely used, the sensed signal of the current is negative. As a result, it requires an additional circuit to be applied to general digital controller ICs. The proposed diode current sensing method not only minimizes the peripheral circuit around the digital IC but also consumes less power to sense current information than the inductor current sensing method. The feasibility of the proposed technique is verified by experiments using a 500W power factor correction (PFC) boost rectifier.

• 전기학회논문지
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• 제65권4호
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• pp.576-585
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• 2016

The current control methods of Y-connected 7 Phase BLDC motor are sine wave current control and square wave control. The sine wave current control method needs dq axis transformation of $7{\times}7$ matrix for current control and very complex. Also this method is not suitable for multi Phase BLDC motor of trapezoidal back emf wave. Therefore, in Y connected multi phase BLDC motor, the square wave current control methods are required. Generally, in the 3Phase BLDC system, Average current control method is used for current control. The average current is obtained that the summation of absolute value of each phase current magnitude is divided by the number of conduction phase. However, if average current control method is applied to multi-phase system, there is a problem that each phase currents are different. This problem affects unbalance of each phase torque and fluctuation of total torque. This paper proposed each phase current control method of Y connected 7Phase BLDC system. Proposed method is used for PI controller of each phase for each phase current control. This method can perfect square wave current control. Also, configuration of the method is easier than DQ axis transformation. Proposed method is verified through simulation and experiments.

• 전력전자학회논문지
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• 제3권3호
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• pp.191-198
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• 1998

본 논문에서는 브러시리스 직류 전동기의 상 전류 제어를 위해 유니폴라 PWM 방식이 적용될 때 상 전환에 의한 토크 맥동을 저감시키기 위한 새로운 전류 제어 방식을 제안한다. 상 전환은 통전된 상의 평균 전압의 순간적인 변동을 야기시켜 전류에 맥동을 발생시키고, 이 맥동 전류는 토크 맥동을 발생시킨다. 본 논문에서는 PWM 패턴에 따를 전환 구간에서의 통전된 상의 평균 전압 변화를 분석하고 평균 전압 변동을 보상하기 위한 전류 제어기를 설계한다. 그리고 실험 결과를 통하여 제안된 방식의 효용성을 입증한다.

• 한국안전학회지
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• 제15권1호
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• pp.100-105
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• 2000

Correlation between propagation of bush-type electrical tree and internal partial discharges(PD) was discussed. We used specimens with needle-plane electrode system made of LDPE(Low Density Polyethylene), observed inception and propagation of electrical tree by optical microscope interfaced with computer and investigated characteristics of phase resolved PD pulses accompanying with propagation of electrical tree. Electrical tree generally growed bush-type tree. PD data detected and analyzed were average discharge current and statistical operator of q-n, $\psi$- $q_{avg}$, $\psi$-n, ${\psi}-q_{max}$ distribution. Parameters used were skewness, kurtosis, average discharge phase, cross-correlation factor, asymmetry and etc. In generally, average discharge current had good linear relationship with propagation of bush type electrical tree on this experiment. Peak discharge magnitude and repetition rate were increased, but they had not good linear relationship.p.

• 한국안전학회지
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• 제28권4호
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• pp.38-42
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• 2013

This study performed the quantitative distribution analysis of created voids to an insulator when applying general flame and DC short-circuit current to 2.5 $mm^2$ HIV (600 V Grade Heat-Resistant Polyvinyl Chloride Insulated Wires). The diameter of cross-section of HIV normal product and the radius of conductor were measured to be 3.3 mm and 1.8 mm. The exterior of HIV exposed to general flame showed severe carbonization and its interior exhibited voids created by dechlorination reaction. This study observed the characteristics that, when the shortcircuit current applied for 2 seconds from a DC 12 V lead battery, the conductor and neighboring insulator were melted, causing the insulator adhering to the conductor. On average, 87 voids were created on 10 mm of the HIV. The average diameter of voids was 0.25 mm. In addition, it was found that, when the short-circuit current applied for 4 seconds, the interior of insulator in contact with conductor severely carbonized and showed exfoliation phenomenon. On average, 47 voids were created, with more voids at the bottom. The average diameter of voids was 0.20 mm. When the short-circuit current for 6 seconds, most parts of upper part of conductor was carbonized, 20 voids were created. The average diameter of voids was measured to be 0.24 mm. It could be seen that the created voids received little influence by the type of energy source and the number of created voids was reduced as the energy supply time increased.

• 한국해양공학회지
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• 제19권2호
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• pp.53-59
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• 2005

The effect of pH on the corrosion characteristics in the dissimilar friction welded zone of IN713LC-SCM440 in the loaded torsional stress was studied. The corrosion experiment was performed for 120 hours on the specimens with five steps of pH. The surface corrosion pattern of the SCM440 area showed global corrosion and narrow pitting, which was caused by galvanic corrosion between friction welded IN713LC and SCM440, but corrosion did not proceeded from the IN713LC area. The average relative electrode potential gradually tends to decrease with the elapse of the immersion time in the acidity area. The average corrosion current also gradually tend to decrease The corrosion rate showed a larger value when the average relative electrode potential was higher and the average relative current was lower. The corrosion rate showed a larger value when the average relative electrode potential was higher in the acidity area, and it showed large when the average relative electrode potential was lower in the alkalinity area.