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

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1571-1573
• /
• 1994

In order to substitute for the conventional measuring system which could bring about technical inconveiences, measuring techniques for the fast transient high voltage upto 100 kV and small signals less than 1 V are developed by use of Laser Source with Packets cell. for the former, capacitive voltage divider was specially designed for reducing the impulse voltage less than the half-wave voltage of pockets cell. For the tatter, interferometer type was employed as a mean to removing the fluctuation of Laser output intensity. And also the main beam through the Pockels cell and the reference beam from the Laser source are seperated before being detected respectively by photo diodes. And then, these two signals are amplified and compared for detecting only the small signals applied across the Pockels cell. Throughout this work, Laser-based measuring system is likely to enable us, at this moment, to detect correctly lightning impulse voltage upto 100 kV and the small signals less than 1 V upto the 2 MHz. Such a system could be employed as a possible diagnostic measuring system at the substation.

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

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.7
• /
• pp.530-533
• /
• 2010

The proton exchange membrane fuel cell (PEMFC) holds great promise of clean power. However, in practical applications which use the PEMFC as the power source, the output voltage from the fuel cell undergoes a transient response especially during acceleration and deceleration. This paper presents the relationships between the charge curves of the internal voltage rise, discharge curves of the internal voltage drop, the voltage with a time constant $V_{\tau}$ and finally, the load and time constant $\tau$ of $FC_1$ and $FC_2$, connected both in series and in parallel.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.2
• /
• pp.160-166
• /
• 2015

This study proposes an improved cell balancing circuit for fast equalization among lithium-ion (Li-ion) batteries. A simple voltage sensorless charge balancing circuit has been proposed in the past. This cell balancing circuit automatically transfers energy from high-to low-voltage battery cells. However, the circuit requires a switch with low on-resistance because the balancing speed is limited by the on-resistance of the switch. Balancing speed decreases as the voltage difference among the battery cells decrease. In this study, the balancing speed of the cell balancing circuit is enhanced by using the auxiliary circuit, which boosts the balancing current. The charging current is determined by the nominal battery cell voltage and thus, the balancing speed is almost constant despite the very small voltage differences among the batteries. Simulation results are provided to verify the validity of the proposed cell balancing circuit.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.1
• /
• pp.135-140
• /
• 2022

In addition to the stack that directly generates electricity by the reaction of hydrogen and oxygen, the fuel cell power generation system has a reformer that generates hydrogen from various fuels such as methanol and natural gas. It also consists of a power converter that converts the DC voltage generated in the stack into a stable AC voltage. The fuel cell output of such a system is direct current, and in order to be used at home, an inverter device that converts it into alternating current through a power converter is required. In addition, a DC-DC step-up converter is used to boost the fuel cell voltage to about 30~70V, which is the inverter operating voltage, to about 380V. The DC-DC step-up converter is a DC voltage variable device that exists between the fuel cell output and the inverter. Accordingly, since a constant output voltage of the converter is generated in response to a change in the output voltage of the fuel cell, the inverter can receive constant power regardless of the voltage change of the fuel cell. Therefore, in this paper, we discuss the detailed hardware design of the full-bridge converter, which is the main power source of the inverter that receives the fuel cell output voltage (30~70V) as an input and is applied to the grid among the members of the fuel cell power generation system.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.54 no.5
• /
• pp.245-252
• /
• 2005

The fuel cell systems are one of very useful energy sources. The systems have advantages as renewable and environmental sources. To obtain AC components from fuel cells, it needs inverters. A multilevel converter is used as a power conversion system for a high power fuel cell system. Through harmonic analysis, it is shown that the harmonic components and THD increase while a fundamental component of output decreases as voltage droop increases. To solve the voltage disturbance problems, three different approaches are investigated in this paper; installation of a boost converter at the fuel cell output, control of pulse widths, and use of ultracapacitors. The proposed three approaches are analyzed and compared through simulation and experimental results.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.867-869
• /
• 1993

In generally Boost Converter is used for Fuel Cell System. Because the output voltage of fuel cell is too small and greatly depends on the load condition, Boost Converter are required to boost and regulate the Fuel Cell voltage for per conversion efficiency. In this Paper, 6-phase Boost Converter is used to boost the Fuel Cell Voltage and regulate the output voltage. Multi phase converter hag some advantages such as low ripple and filter sine. About the Peak Current Control and compare of the Ripple Current of Boost Converter, we have studied.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.2
• /
• pp.113-118
• /
• 2005

This paper shows a satellite battery cell voltage monitor system to make differential voltage measurements when one or both measurement points are beyond voltage range allowed by a conventional differential amplifier. This system is particularly useful for monitoring the individual cell voltage of series-connected cells that constitute a rechargeable satellite battery in which some cell voltages must be measured in the presence of high common mode voltage.

• Transactions of the Korean hydrogen and new energy society
• /
• v.21 no.3
• /
• pp.149-157
• /
• 2010

The electromagnetic characteristics of FCEVs (fuel cell electric vehicles) are much different from the existing combustion engine cars as well as hybrid, plug-in-hybrid, and pure electric vehicles due to the high voltage/current generated by a fuel cell stack which uses a compressed hydrogen gas reacted with oxygen. To operate fuel cell stack efficiently, BOP (Balance of Plant) is essential. BOP systems are used many not only for motors in water pump, air blower, and hydrogen recycling pump but also inverters for these motors. Since these systems or components are connected by high voltage cables, EMC (Electromagnetic compatibility) analysis for high voltage/current cable is the most important element to prevent the possible electric functional safety errors. In this paper, electromagnetic fields of high current/voltage cable for FCEVs is studied. From numerical analysis results, time harmonic magnetic field strength of high current/voltage cable have difference of 20～28 dB according to phase. EMI result considered ground effect of FECV at 10 m shows difference of 14.5 dB at 30 MHz and 2.8 dB at 230 MHz compared with general cable.