• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.1
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• pp.55-65
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• 2016

This paper proposed a new control method which is capable of controlling circulating current considering current capacity of switching device. In the unbalanced voltage conditions, active power and reactive power have double line frequency. Thus, in order to provide active power without ripple, it is necessary to inject the negative sequence current components. However, when the negative current components is injected, it increases the total current flowing in the Arm, and in the Sub-module(SM) the current more than rated is impressed, which leads to destroy the system. Also, in impressing the circulating current reference of each arm, conventional control method impressed applicable $i_{dck}/3$ in the case of balanced voltage conditions. In the case of unbalanced conditions, as arm circulating current of three phase show difference due to the power impressed to each arm, reference of each arm is not identical. In this study, in the case of unbalanced voltage, within permitted current, the control method to decrease the ripple of active power is proposed, through circulating current control and current limitations. This control method has the advantage that calculates the maximum active power possible to generate capacity and impressed the current reference for that much. Also, in impressing circulating current reference, a new control method proposes to impress the reference from calculating active power of each phase. The proposed control method is verified through the simulation results, using the PSCAD/EMTDC.

• Journal of Power Electronics
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• v.18 no.1
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• pp.171-184
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• 2018

Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current $2^{nd}$ order fluctuations, and 3) elimination of the DC-current $2^{nd}$ and $6^{th}$ order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

• 전기의세계
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• v.29 no.12
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• pp.791-797
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• 1980

This paper is concerned with the study of improving the faults of phase control scheme and suggesting a new approach to the control of load circuit with AC source. AC current control can restrict the magnitude of current within the given upper and lower current and make current continuous during every cycle. Also the harmonic contents of current can be greatly reduced using this control scheme. Analog computer and digital computer simulations reveal that the current control scheme is superior to the phase control scheme in controlling the power supply to the load R-L. Experimintal results demonstrate the feasibility and verify the operation of current controlled system.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.399-402
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• 1999

The single sensor technique reconstructing phase currents from the dc-link current without phase current sensors in proposed. When the duration of active vector is too short for the snubber current to reduce, the dc-link current including the snubber current gives large detection error. The solution is presented by analyzing the snubber current and modifying the switching sequences. This scheme is simple, requires only one sampling a period and has good results for detecting the phase currents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.379-382
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• 2002

GaAs has wide band gap, Therefore that malarial can used high Temperature application. in this paper explain to current-voltage characteristics of thermal effect. we experiment on thermal test of current-voltage characteristics and gate leakage current with real device. As a result, we propose a current-volatage characteristics model. that model base on gate leakage current, and gate leakage current influence gate source voltage.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.807-814
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• 1999

In this paper, it is shown that high frequency current can be controlled to concentrate near the desired path in a conducting plate. A conducting plate is modelled to examine current distribution. And current distribution is analyzed in view of the frequency and geometric characteristics of current path. The high frequency current behavior from the analysis is compared with the experiments. The results, obtained by the experiments of test specimens, are in good agreement with the analytical results.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.289-292
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• 2001

A Novel fully-differential bipolar current-controlled current amplifier(CCCA) for electrically tunable circuit design at current-mode signal processing were designed. The CCCA was consisted of fully-differential subtracter and fully-differential current gain amplifier. The simulation result shows that the CCCA has current input impedance of 0.5 Ω and a good linearity. The CCCA has 3-dB cutoff frequency of 20 MHz for the range over bias current 100$mutextrm{A}$ to 20 ㎃. The power dissipation is 3 mW.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.335-340
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• 1996

The item and structure of current detector depends on the current in conductors. The Hall current detector of these detectors is to use the variation of Hall voltage to conductor's current and it is very difficult for the conventional type to detect small current. In this paper we study experimented-method that detect AC current by using the magnetic modulation method the current, 0[mA]~100[mA]. The experiments results in 5 percent against the conventional, 20 percent in linear error, 0.12[.DELTA.mV/.DELTA.mA] to conventional type, 50[.DELTA.mV/.DELTA.mA] in sensitivity. (author). 7 refs., 15 figs.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.3
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• pp.166-172
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• 2004

Arc Fault Current is an electric discharge which is occurred in two opposite electrode. In this Paper, arc current control algorithm is designed for the interruption of arc fault current which is occurred in the low voltage network. This arc Is one of the main causes of electric fire. Arc fault in electrical network has the characteristics of low current, high impedance and high frequency. Conventional control algorithm does not have the arc current interrupt function. Hence, Control algorithm of arc current is designed for the interruption of arc fault current which has the modified arc characteristics.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.25-36
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• 1994

The inward tail current after a short depolarizing pulse has been known as Na-Ca exchange current activated by intracellular calcium which forms late plateau of the action potential in rabbit atrial myocytes. Chloride conductance which is also dependent upon calcium concentration has been reported as a possible tail current in many other excitable tissues. Thus, in order to investigate the exsitance of the calcium activated chloride current and its contribution to tail current, whole cell voltage clamp measurement has been made in single atrial cells of the rabbit. The current was recorded during repolarization following a brief 2 ms depolarizing pulse to +40mV from a holding potential of -70mV. When voltage-sensitive transient outward current was blocked by 2 mM 4-aminopyridine or replacement potassium with cesium, the tail current were abolished by ryanodine$(1{\mu}M)$ or diltiazem$(10{\mu}M)$ and turned out to be calcium dependent. The magnitudes of the tail currents were increased when intracellular chloride concentration was increased to 131 mM from 21 mM. The current was decreased by extracellular sodium reduction when intracellular chloride concentration was low(21 mM), but it was little affected by extracellular sodium reduction when intracellual chloride concentration was high(131 mM). The current-voltage relationship of the difference current before and after extracellular sodium reduction, shows an exponential voltage dependence with the largest magnitude of the current occurring at negative potentials, with is similar to current-voltage relationship at negative potentials, which is similar to current-voltage relationship of Na-Ca exchange current. The current was also decreased by $10{\mu}M$ niflumic acid and 1 mM bumetanide, which is well known anion channel blockers. The reversal potentials shifted according to changes in chloride concentration. The current-voltage relationships of the niflumic acid-sensitive currents in high and low concentration of chloride were well fitted to those predicted as chloride current. From the above results, it is concluded that calcium activated chloride component exists in the tail current with Na-Ca exchange current and it shows the reversal of tail current. Therefore it is thought that in the physiologic condition it leads to rapid end of action potential which inhibits calcium influx and it contributes to maintain the low intracellular calcium concentration with Na-Ca exchange mechanism.