• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.76-83
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• 2014

During PEMFC(Proton Exchange Membrane Fuel Cell) operation monitoring and diagnosis are important issues for reliability and durability. Stack defect can be followed by a critical cell voltage drop in the stack. One method for monitoring the cell voltage is CVM(Cell Voltage Monitoring), where all cells in the stack are electrically connected to a voltage measuring system and monitored these voltages. The other methods are based on the EIS(Electrochemical Impedance Spectroscopy) and on nonlinear frequency response. In this paper, intermodulation(IM) method for diagnosis PEMFC stack is introduced. To detect one or more critical PEMFC cell voltage PEMFC stack is excited by two or more test sinusoid current, and the frequency response of the stack voltage is analyzed. If one or more critical cell voltage exists, higher harmonics on the voltage frequency spectrum will appear. For the proposed IM method, stack simulation and experiments are conducted.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.90.1-90.1
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• 2011

This technology is applicable to Electrical vehicle that using Energy from Hydrogen Fueled Cell. Electricity & water is got from chemical reaction between H2 & O2 in stack. This technology is used when fault diagnosis of Fuel cell is needed. It is General method that measure each cell's voltage of stack for fault diagnosis. but, this technology is method of measuring entire voltage of stack. For this reason, fault diagnosis system is simplified and cost of system is lower than previous one. In normal stack condition, characteristic graph of voltage-current has linearity. In fault stack condition, it has non-linearity. we use this characteristic to diagnosis of stack fault. In this technology, Specific frequency current is injected into stack & Stack voltage is measured in response. After that, stack voltage difference is analyzed to diagnosis of stack fault. Presently, Development of current injection module & basic program of THDA is finished. in future we will develop the technology of precise measurement technology about entire stack voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.396-401
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• 2000

In order to accurately measure the high voltage of 22.9[kV] power distribution lines we investigated the temperature dependence of measuring voltage on the number of stack layers in the voltage measurement system made from single and stack voltage divider capacitors (22, 44, 66 layers, respectively). Temperature coefficient of dielectric constant(TC$\varepsilon_{{\gamma}}$/)of voltage divider capacitors which were fabricated by BaTi $O_3$system ceramics showed the variations from -2.28% to +1.69% in the range of -25[$^{\circ}C$] ~50[$^{\circ}C$]) was decreased with increasing of stack number and the stack element of 66 layers showed the least error of $\pm$0.87%or of $\pm$0.87%.

• Journal of IKEEE
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• v.23 no.3
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• pp.1015-1019
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• 2019

In this paper, a new ESD protection device is proposed to improve the trigger voltage and robustness. The HHVSCR and the proposed device were compared to verify the trigger voltage, the holding voltage and the robustness. The gate length was modified to verify the electrical characteristics. The trigger voltage, the holding voltage and the robustness were certified by comparing the proposed device and the stacking structure.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.286-286
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• 2009

A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of $5cm^2$. The passive stack has 12cells with an active area of $16cm^2$. When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.319-322
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• 1999

In order to accurately measure the high voltage of 22.9[kV] power distribution lines, we investigated the temperature dependence of measuring voltage for single element and stack elements(22, 44, 66 layers, respectively). When one line voltage is 13, 20O[V], the error of measuring voltage with temperature(-25[$^{\circ}C$]~50[$^{\circ}C$]) was decreased with increasing of stack number and stack element with 66 layers was the least error of ${\pm}0.87%$.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.881-890
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• 2011

Analyses of performance and behavior of the individual PEM fuel cells (PEMFC) under different operating conditions are of importance optimally to design and efficiently to operate the stack. The paper focuses on experimental analyses of a two-cell stack under different operating conditions, which performance and behavior are measured by the voltage of a cell as well as the stack. Experimental parameters include stoichiometric ratio, temperature of the air supplied under different working stack temperatures and loads. Results showed that the cell voltages are dominantly influenced by the temperature of the air supplied among others. In addition, an inherent difference between the first and the second cell voltage exists because of the tolerances of the cell components and the resulting different over-potentials at different equilibrium states. Furthermore, it is shown that the proton conductivity in the membranes conditioned by the humidity in the cathode channel highly affects the voltage differences of the two cells.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.134-138
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• 2004

The discrepancies between theoretical values and measured data of PEFC(Proton Exchange Fuel Cell) is carried out for the machine tool power generation. Rudimental approach of theoretical fuel cell open circuit potential using Gibbs free energy is employed for the examination of PEFC module. The stack temperature, stack voltage and stack current are measured during the operation of PEFC module. It is found that stack voltage and current values show the pronounced discrepancy with the results calculated by Gibbs free energy approach. It is analysed that the discrepancy is due to activation polarization, concentration overvoltage and ohmic overvoltage.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.569-572
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• 2007

In this paper, research about SVM(stack voltage monitoring) module is written, which studied to detect the failure mode of stack and stop stack driving. It is important role for SVM module to monitor the cell voltage and also, transfer those data to Supervisor controller. SVM module needs accurate measurement to detect failure mode, because the cell voltage is very small value under a few [V]. For improving these cost and technical efficiency, the electric characteristic experiment is made with the measurement circuit designed by using precision resistor.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.376-379
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• 2006

In this paper, stack voltage monitoring module is developed which monitor cell voltage of the fuel cell stack and transfer it to the main controller for monitoring fault and stopping drive when the trouble is happened in the fuel cell stack. Especially, the circuit, for monitoring each cell voltage of several hundreds cells in stack, is designed and analyzed. The connector is also developed for making wire harness simple and low cost because wire harness is complicated when the cells are connect each monitoring circuit.