• Journal of Hydrogen and New Energy
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• v.24 no.5
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• pp.393-400
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• 2013

The air supply system has a significant effect on the efficiency of polymer electrolyte membrane fuel cell (PEMFC) systems. The performance and efficiency of automotive PEMFC systems are greatly influenced by their air supply system configurations. This study deals with the system simulation of automotive PEMFC systems using MATLAB/Simulink framework. In this study, a low-pressure operating PEMFC system adopting blower sub-module (turbo-blower) is modeled to investigate the effects of stack operating temperature and air stoichiometry on the parasitic power and efficiency of automotive PEMFC systems. In addition, the PEMFC net system efficiency and parasitic power of air supply system are mainly compared for the two types (low-pressure operating and high-pressure operating) of automotive PEMFC systems under the same net power conditions. It is suggested that the obtained results from this system approach can be applied for establishing the novel operating strategies for FC vehicles.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.990-991
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• 2015

To drive a magnetron injection gun, thsi paper decribes a design, fabrication and analysis results of proposed compact capacitor charging power supply (CCPS) formed resonant full-bridge inverter for electron gun power supply (EGPS). EGPS needs the -40 kV output voltage and 280 kW output power for few seconds continuously and have to be designed for the rise and fall time to be less than 1 ms with the ripple stability of output voltage of lower than 1%. In order to meet the requirements, we used eight resonant full-bridge modules operated in parallel. Each resonant full-bridge module can supply the current of 0.9 A and the voltage of 40 kV, and is operated by N-phase shift switching pattern. In this paper, we present the design, simulation and test results of interleaved CCPS.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.26-36
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.4
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• pp.41-49
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• 2016

Smart Grid is a next generation of new power growth electrical grid which provide high quality of electrical service by using Information Technologies to increase intelligence and performance. By using Smart Grid system, it can support energy management such as increase quality of electrical power, decrease energy and decrease emissions. However, Smart Grid uses information of energy consumption and when Smart Grid collects information, it will create private information. In this thesis, it will address issues of security private information which caused by Smart Grid for administrative measure and efficiency of Smart Grid in domestic. Also, cryptographic module algorithm, latest security solutions and strong wireless security policy for network environment such as wireless communication Iinternet are require for Smart Grid perform successfully and protect national power network equipment from cyber-attack and can stop leakage of user's personal information. Finally, it is urgent to prepare protection measures of National industrial facilities and power grid which can prepare for a cyber terrorism and penetration attacks and build emergency countermeasure management team for Smart Grid are require for safe Smart Grid environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.175-179
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• 2005

The main objective of this paper is to module design and pressure relief test a new type of polymer gapless surge arrester for power distribution line. Metal oxide surge arrester for most electric power system applications, power distribution line and electric train are now being used extensively to protect overvoltage due to lightning. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. When breakdown of gapless elements in a surge arrester occurs due to flashover, fault short current flows through the arrester and internal pressure of the arrester rises. The pressure rise can usually be limited by fitting a pressure relief diaphragm and transferring the arc from the inside to the outside of the housing. However, there is possibility of porcelain fragmentation caused by the thermal shock, pressure rise, etc. Non-fragmenting of the housing is the most desired way to prevent damage to other equipment. The pressure change which is occurred by flashover become discharge energy. This discharge energy raises to damage arrester housing and arrester housing is dispersed as small fragment. Therefore, the pressure relief design is requested to obstruct housing dispersion.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.971-976
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• 2012

A 150 kJ compact capacitive pulsed power system (CCPPS) capable of delivering electrical energy into an electrothermal chemical (ETC) gun on a vehicle has been studied. The CCPPS provides pulsed electrical energy into a capillary plasma injector which generates plasma of tens of thousands $^{\circ}K$ in temperature and has a nonlinear resistance depending on the current. The design requirements of the CCPPS are as follows: the maximum power of 250 MW, the pulse width of about 0.6 ms, the volume of no more than 0.5 cubic meter, the efficiency of energy transfer over 80 % and the repetition rate of 4~5 times per minute. The constructed CCPPS is composed of four 37.5 kJ capacitor bank modules in parallel to make a trapezoid pulse shape and to satisfy the design requirements. Each module is designed to achieve high reliability, safety, efficiency and energy density to endure severe operating conditions. The results of the performance test on the CCPPS using a 120 mm ETC gun are described.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.7-14
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• 2014

Inverter module, which feeds the converted power to the traction motor for EMU. Consists of the power semiconductors with their gate drive unit(GDU)s and the control computer for driving, voltage, current and speed controls. Electrolytic condenser, connected to the gate drive unit and a core component to drive the power semiconductor, has problems such as reduction in lifetime and malfunction caused by electrical and mechanical characteristic changes from heat generation during high speed switching for generation of stable power. In this study, To check the service life of electrolytic condenser, the test was carried out in two ways. First, In the case of accelerated life testing of condenser, the Arrhenius model is a way of life testing. Another way is to analyze the reliability of the failure data by the method of parametric data analysis. Eventually, life time by accelerated life test than a method of failure data analysis(Weibull distribution) was found to be slightly larger output.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.921-930
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• 2016

This paper proposes a design and control method for a high-voltage direction current modular multilevel converter (HVDC-MMC) considering the capacitor voltage ripple of the submodule (SM). The capacitor voltage ripple consists of the line frequency and double-line-frequency components. The double line- frequency component does not fluctuate according to the active power, whereas the line-frequency component is highly influenced by the grid-side voltage and current. If the grid voltage drops, a conventional converter increases the current to maintain the active power. A grid voltage drops, current increment, or both occur with a capacitor voltage ripple higher than the limit value. In order to reliably control an MMC within a limit value, the SM capacitor should be designed on the basis of the capacitor voltage ripple. In this paper, the capacitor voltage ripple according to the grid voltage and current are analyzed, and the proposed control method includes a current limitation method considering the capacitor voltage ripple. The proposed design and control method are verified through simulation using PSCAD/EMTDC.

• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.1
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• pp.1-6
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• 2021

In this paper, to expand the use of standalone street lights, an algorithm for controlling LED energy consumption was proposed. The proposed method uses an LED module of a standalone street light divided into n zones. This is a method of reducing total power consumption by preventing the increase in power consumption due to high heat generation by weakly operating the entire LED according to the illuminance. When the amount of sunlight decreases, the whole LED operates weakly and then brightens, and unlike streetlight that act as streetlight, a method of dividing LEDs by area and limiting the number of LEDs operating according to illumination intensity was proposed. This is a way to use a lot of time with limited battery capacity by reducing the generation of heat that consumes the most power in streetlight. It is also a method of continuously changing the initial usage area to improve the total usage time of the LED substrate. As a result of the experiment, it was found that the proposed method extends the service time because it generates less heat than the conventional stand-alone streetlight.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.505-508
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• 2016

In city, tracing of power transmission lines is difficult due to compound installation of overhead and underground lines, transposition, bad view caused by trees or big buildings. It is hard problem for electrical technician on site to trace power transformers or power lines to serve customers in 3 phase -4 wires power distribution systems. It is necessary that the correct and fast tracing method is required for load balancing among distribution lines. Old technology use to trace lines with high power impulse injection. Our proposed method uses to trace lines with very small power high frequency signal injection. Simulation models for 3-phase power transformers, 3-phase wire lines, and customer loads are described to investigate the transmission characteristics of high frequency power line carrier. Distribution lines have only a limited ability to carry higher frequencies. Typically power transformers in the distribution system prevent propagating the higher frequency carrier signal. The proposed method uses the limited propagation ability to identify the power transformer to serve customers. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building. Also some simulations are done to help and understand the concepts by using MATLAB Simulink simulator.