• Journal of Power Electronics
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• 제16권5호
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• pp.1650-1660
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• 2016

This paper proposes a compensator to eliminate the DC bias of inductor current. This method utilizes an average-current sensing technique to detect the DC bias of inductor current. A small signal model of the DC bias compensation loop is derived. It is shown that the DC bias has a one-pole relationship with the duty cycle of the left side leading lag. By considering the pole produced by the dual active bridge (DAB) converter and the pole produced by the average-current sensing module, a one-pole-one-zero digital compensation method is given. By using this method, the DC bias is eliminated, and the stability of the compensation loop is ensured. The performance of the proposed compensator is verified with a 1.2-kW DAB converter prototype.

• 한국자기학회지
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• 제23권3호
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• pp.94-97
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• 2013

본 연구에서는 원통형 페라이트 코어와 페라이트코어를 관통하는 구리선, 그리고 검출 코일을 이용하여서 직교형 플럭스게이트 센서를 제작하고, 직류 바이어스 전류가 출력 감도에 미치는 영향에 대해서 조사하였다. 제작한 직교형 플럭스게이트 센서의 출력 및 감도는 구동주파수에 의존하였으며, 이는 검출코일 임피던스의 주파수특성이 나타내는 경향과 유사하였다. 직류 바이어스 전류가 교류 구동전류의 크기에 비해서 대략 50% 이상일 때 출력감도가 최대가 되었으며, 그 보다 큰 직류 바이어스 전류에 의해서는 출력감도가 포화되는 경향을 나타내었다.

• Transactions on Electrical and Electronic Materials
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• 제12권5호
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• pp.197-199
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• 2011

In this paper, the bottom-gate thin-film transistors (TFTs) were fabricated with an amorphous/microcrystalline Si double layer (DL) as an active layer and the variations of the electrical characteristics were investigated according to the DC bias stresses. Since the fabrication process of DL TFTs was identical to that of the conventional amorphous Si (a-Si) TFTs, it creates no additional manufacturing cost. Moreover, the amorphous/microcrystalline Si DL could possibly improve stability and mass production efficiency. Although the field effect mobility of the typical DL TFTs is similar to that of a-Si TFTs, the DL TFTs had a higher reliability with respect to the direct current (DC) bias stresses.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.699-702
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• 2002

A DC current sensor is disclosed in which two pairs of saturable cores are provided so as enclose a conductor carrying a direct current to be measured. On each of the saturable cores, a bias winding, a feedback winding and an output winding are wound. Circuit for detection of an asymmetry in the magnetization current, generated by a reference alternating voltage, in a signal-conditioner. The reference alternating voltage is fed to the respective series circuits such that no resultant induction current is induced in the modulating current. The voltages over the resistor form input signals for two peak value detectors, the strength of the output signal of which represents the degree of asymmetry of magnetization current. This paper describes the development a DC current sensor and its signal-conditioner.

• 전기학회논문지
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• 제60권4호
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• pp.789-795
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• 2011

It is necessary to accurately predict converter losses for optimized design of a high-power DC-DC converter. The losses of switching devices and inductor among the elements of the converter take significantly greater proportion. The current ripple will be determined by the size of the inductance and this inductance value varies depending on the DC amount of inductor current. As the inductance changes according to load current, the change influences not only the inductor loss itself but also the total converter loss. In this paper, for more accurate design of a bi-directional DC-DC converter for 30kW-class energy storage system, more accurate computational model is proposed considering inductance variation according to the load current change. The inductance changes using variable magnetic cores are verified and converter efficiency is tested through simulations and experiments.

• 한국표면공학회지
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• 제50권5호
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• pp.398-404
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• 2017

In order to study the AC driving mechanism for OLED lighting, the fluorescent OLEDs were fabricated and the electroluminescent characteristics of the OLEDs by AC forward bias were analyzed. In the case of the driving method of OLED by AC forward bias under the same voltage and the same current density, degradation of luminescent characteristics for elapsed time progressed faster than in the case of the driving method by DC bias. These phenomena were caused by the peak voltage of AC forward bias which is ${\sqrt{2}}$ times higher than the DC voltage. In addition, the degradation of the OLED was accelerated because the AC forward bias had come close to the upper limit of the allowable voltage range even though the peak voltage didn't exceed the allowable range of the OLED. However, the fabricated fluorescent OLED showed little degradation of OLED characteristics due to AC forward bias from 0 V to 6.04 V. Therefore, OLED lighting by AC driving will become commercialized if sufficient luminance is realized at a voltage at which the characteristics of the OLED are not degradation by the AC driving method.

• 한국전기전자재료학회논문지
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• 제29권4호
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• pp.247-249
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• 2016

In this study, we investigated the color change of the normal light gray granite as the high value color granite. By coating the metal catalyst liquid on the surface of granite stone, the metal particles were penetrated into the granite and the color of granite was changed permanently through the annealing treatment. To increase penetration depth into the granite, we used DC (direct current) bias. Two kinds of bias were used such as DC bias and pulse DC bias. And the penetration time was changed as 30 and 60 min. In all cases, the color granite were successfully obtained. Regardless of the catalyst reaction time, the penetration depth was increased by using the bias treatment. We obtained a penetration depth of 21 mm with the DC pulse bias during 60 min.

• 전기학회논문지
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• 제65권3호
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• pp.439-444
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• 2016

The method for extracting the SPICE model parameter of Schottky diode under DC forward bias is proposed. A method for improving the accuracy of the SPICE model parameter at various temperatures is proposed. Three analysis steps according to the magnitude of the current is used in order to extract the parameters effectively. At each analysis step, initial parameters are calculated by using the current-voltage equations and the Levenberg-Marquardt analysis is proceeded. To verify the validity of the proposed method, the SPICE model parameters for the BAT45 and FSV1045 under DC forward bias is extracted. Schottky diode currents obtained from the proposed method shows the average relative error of 6.1% and 9% compared with the measured data for the BAT45 and FSV1045 sample at various temperatures.

• 한국초전도ㆍ저온공학회논문지
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• 제6권2호
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• pp.29-34
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• 2004

The linear type flux pump aims to compensate a little bit decremental persistent current of the HTS magnet in NMR and MRI spectrometers. The flux pump mainly consists of DC bias coil, 3-phase AC coil and Nb foil. The persistent current in closed superconductive circuit can be easily adjusted by the 3-phase AC current, its frequency and the DC bias current. In the experiment, it has been investigated that the flux pump can effectively charge the current in the load coil of 543 mH for various frequencies in 18 minutes under the DC bias of 10 A and the AC of 5 $A_{rms}$. The maximum magnitudes of pumping current and load magnet voltage are 0.72 A/min and 20 ㎷, respectively. Based on simulation results by the FEM are proved to nearly agree with experimental ones.

• 한국결정성장학회지
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• 제15권5호
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• pp.198-201
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• 2005

Carbon nanofibers were formed on silicon substrate which was applied by negative direct current (DC) bias voltage using microwave plasma-enhanced chemical vapor deposition method. Formation of carbon nanofibers were varied according to the variation of the applied bias voltage. At -250 V, we found that the growth direction of carbon nanofibers followed the applied direction of the bias voltage. Based on these results, we suggest one of the possible techniques to control the growth direction of the carbon nanofibers.