• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.3081-3083
• /
• 2000

Fuel cell/battery hybrid power systems were studied to develop high efficient zero-emission fuel cell electric vehicles, Fuel cells were used as an auxiliary energy source and batteries were used as a transient power source. The fuel cell system is used to supply the average power demand. Dynamic response of the hybrid systems was simulated using PSPICE program and also tested experimentally, The results can be used to design the interface module and to determine the power requirement between the fuel cell unit and the battery pack.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.2
• /
• pp.187-195
• /
• 2023

Data centers not only consume significant electricity to operate IT equipment, but also use a lot of electricity to cool the heat generated by IT equipment. The waste heat of a high-temperature polymer electrolyte fuel cell (HT-PEFC) is capable of producing cooling , so it can be effectively applied to data centers that require cooling throughout the year. The energy-saving effects of the proposed combined cooling, heat and power (CCHP) system using HT-PEFC. That was analyzed based on the annual energy consumption data of a specific data center. When the system was running at 100% of the year, It was shown that the installation of 1 MW of the proposed system can save 3,407 MWh of electrical energy per year. In addition, compared to the existing system, the annual power usage effectiveness can be improved from 2.0 to 1.57 and 6,293 MWh of extra heat energy per year can be produced to sell. Furthermore, sensitivity analysis was performed on the fuel cell operating temperature and current density to guide the appropriate installation capacity of the proposed system.

• Proceedings of the KIPE Conference
• /
• 2003.07b
• /
• pp.701-706
• /
• 2003

Fuel cell is remarkable for one of the clean energy recently. But in the fuel cell case, it has characteristics with low voltage and high current. Therefore, for using domestic power, it should be changed to the power source with commercial voltage and frequency. In this paper fuel cell simulator having electrical characteristics is designed and constructed instead of fuel cell stack. Voltage generated from fuel cell is from 39V to 72V dc and should be boosted to 400v do for home appliances. A stand alone system including the inverter and DC/DC converter for the fuel cell is then proposed. Experimental result is used to support the analysis.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.2
• /
• pp.211-217
• /
• 2016

The fuel cell based auxiliary power unit (APU) is promising for power source of armed vehicles due to its silence and high efficiency. Especially, the on board hydrogen generation and fed to fuel cell system was core technology of this power system. In this study, we analyzed the performance of the Auto thermal reactor (ATR) that produce the hydrogen from the fuel, integrated High temperature polymer electrolyte fuel cell (HT-PEFC) by Aspen plus software. The fuel was designed as a n-dodecane for analysis of military fuel (JP-8).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.9
• /
• pp.62-70
• /
• 2010

Fuel cell system which can solve the environmental problem is receiving attention. To use utility power necessary power conversion system from low voltage that is generated by fuel cell system. because fuel cell has special characteristic of low voltage high current. To improve PCS's efficiency the paralleling method is used. Available the method could reduce the switching loss. But the existing research could not be found optimal result and accompanying several effects. In this study analysis several effects causing the parallel method. The effects have been demonstrated through simulations and experiments.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.326-328
• /
• 2005

In order to reduce the capital and overall operating cost of a fuel-cell system, a high-efficiency fuel-cell power inverter with a simple framework is required. The high-order two-inductance two-capacitance (LLCC) resonant technique is adopted in this study to implement a low-frequency 60-Hz sine wave voltage inverter utilized in the proton exchange membrane fuel-cell (PEMFC) system. The methodology for inverting dc voltage into low-frequency ac boltage is usually generated by the pulse-width-modulation (PWM) technique. However, the PWM-type inverter output has high-frequency harmonic components. Although an adequately designed filter could be utilized to overcome this problem, there are still some undesirable effects introduced by the high-frequency switching loss, electromagnetic-interference, harmonic current, and load variation. A novel power inverter via the LLCC resonant technique is designed for inverting dc voltage into 60-Hz ac sine wave voltage in the PEMFC system. This circuit scheme has the merits of low harmonic components, soft switching, high efficiency, and simplified implementation. The effectiveness of the proposed resonant inverter used for the PEMFC system is verified by numerical simulations and experimental results.

• Transactions of the Korean hydrogen and new energy society
• /
• v.32 no.6
• /
• pp.470-476
• /
• 2021

In the near future, with the urgent requirement of environmental protection, hydrogen based energy system is essential. However, at the present time, most of the hydrogen is produced by reforming, which still produces carbon dioxide. This study proposes a high-power electrolytic hydrogen production system based on solid oxide electrolysis cell with no harmful emissions to the environment. Besides that, the parametric study and optimization are also carried to examine the effect of individual parameter and their combination on system efficiency. The result shows that the increase in steam conversion rate and hydrogen molar fraction in incoming stream reduces system efficiency because of the fuel heater power increase. Besides, the higher Faraday efficiency does not always result a higher system efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.6
• /
• pp.618-624
• /
• 2020

A portable power supply system for soldiers must be able to supply electric energy corresponding to the power consumption of combat support troops, and have a carrying load in a range that does not impair the combatant's ability to execute operations. In particular, as the total required power of combat equipment increases with the advances in the future soldier system, a portable, lightweight power supply system with high efficiency is essential. A fuel cell has a high energy-to-weight density compared to lithium batteries, which are used mainly as a military power source system. Therefore, it is capable of miniaturization and lightweight, making active R&D to a portable power supply system. In this paper, the characteristics of the fuel cell applied as a portable power supply system, and the R&D trends of domestic and foreign military portable fuel cell systems were investigated. The current status of domestic technology compared to the level of foreign development was analyzed. In addition, future technology development plans are presented based on the consideration factors when developing a portable fuel cell (power supply stability, portability, and cost reduction) so that it can be used when establishing a plan on the development of a portable fuel cell system for the future soldier system.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.5
• /
• pp.1891-1901
• /
• 2017

In this paper, optimal control of the fuel cell and design of a high-efficiency power converter is implemented to build a high-priced fuel cell system with minimum capacity. Conventional power converter devices use a non-isolated boost converter for high efficiency while the battery is charged, and reduce its conduction loss by using MOSFETs instead of diodes. However, the efficiency of the boost converter decreases, since overshoot occurs because there is a moment when the body diode of the MOSFET is conducted during the dead time and huge loss occurs when the dead time for the maximum-power-flowing state is used in the low-power-flowing state. The method proposed in this paper is to adjust the dead time of boost and rectifier switches by predicting the power flow to meet the maximum efficiency in every load condition. After analyzing parasite components, the stability and efficiency of the high-efficiency boost converter is improved by predictive compensation of the delay component of each part, and it is proven by simulation and experience. The variation in switching delay times of each switch of the full-bridge converter is compensated by falling time compensation, a control method of PWM, and it is also proven by simulation and experience.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.4
• /
• pp.61-72
• /
• 2007

This study proposed a high efficiency DC-DC converter with a new current doubler rectifier for fuel-cell systems for use with the Nexa(310-0027) PEMFC from the Ballard Co. The proposed high efficiency DC-DC converter for the fuel-cell system generated ZVS by applying partial resonance and using a phase shift PWM control method. Constantly switching frequency, loss of switching, peak current, and peak voltage were reduced by this system. In addition to this system, two inductors were attached to a rectifier circuit allowing it to be able to provide the direct current(DC) and DC voltage safely to a load with reduced ripple components. Also, by using the newly proposed current doubler rectifier, the high frequency DC-DC converter for the fuel cell system was capable of reaching a highest efficiency of 92[%] as compared to 88.3[%] efficiency in previous results, which means that efficiency increased 3.7[%]. The overall results were confirmed by a simulation and laboratory experiment.