• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.10
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• pp.29-34
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• 2007

The fault current limiting characteristics of a flux-lock type superconducting fault current limiter(SFCL) according to fault angles were investigated. From the electrical equivalent circuit with the magnetization branch, the inner magnetic flux of this SFCL due to fault angles was induced and its effect on the limited fault current was analyzed. From the fault current limiting experiments, the exciting current, which described the saturation of the iron core, was calculated and its dependence on the fault angle was analyzed. Before the fault happened, the exciting current did not happen, that it kept zero value. However, after the fault happened, the exciting current flowed and, the exciting current in case of the additive polarity winding showed higher value than for the case of the subtractive polarity winding. The analysis results were compared with the experimental ones, and experimental results agreed with the analysis ones.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.81-86
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• 2005

Proposed induction-heated system is innovative system which applied special high-frequency power circuit technique for thermal converse technique and IH(Induction-Heating) magnetic induction heating generated from induction-heated metallic package that is for distillation unit. In this occurs not burning, so that the working environment can be improved. This electromagnetic induction heating technique is used high frequency inverter. By using high frequency inverter high frequency alternative current (HFAC) in the range of [kHz] can be made with conventional alternative current In this contribution IGBT module is used for high frequency inverter. In this paper are discussed action analysis and characteristics analysis of 1.5[kW]-Class half-bridge resonant inverter system and resonant metallic packaged. In addition, by using this system,t how two step heating superheated steam generator is developed and application of system are also discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.5
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• pp.481-487
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• 2005

Proposed induction-heated system is innovative system which applied special high-frequency power circuit technique for thermal converse technique and IH(Induction-Heating) magnetic induction heating generated from induction-heated metallic package that is for distillation unit. In this occurs not burning, so that the working environment can be improved. This electromagnetic induction heating technique is used high frequency inverter, By using high frequency inverter high frequency alternative current in the range of [kHz] can be made with conventional alternative current. In this contribution IGBT module is used for high frequency inverter. This paper proposes new fluid heating method. Which is operated as follows. Working coil, which is wrapped outside of pipeline, makes the eddy current. Inside of heating vessel in isolated pipeline the specially designed stainless metallic package is inserted, which can be heated by eddy current losses. And then In this paper are discussed action analysis and characteristics analysis of 5[kW] class full-bridge resonant inverter system and resonant metallic package. In addition, by using this system, how high-efficiency heater is developed and application of system are also discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.1
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• pp.95-103
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• 2008

Proposed induction-heated system is innovative system which applied special high-frequency power circuit technique for thermal converse technique and IH(Induction-Heating) magnetic induction heating generated from induction-heated metallic package that is for distillation unit. In this occurs not burning, so that the working environment can be improved. This electromagnetic induction heating technique is used high frequency inverter. By using high frequency inverter high frequency alternative current (HFAC) in the range of [kHz] can be made with conventional alternative current. In this contribution IGBT module is used for high frequency inverter. In this paper are discussed action analysis and characteristics analysis of 1.5[kW]-Class half-bridge resonant inverter system and resonant metallic package. In addition, by using this system, how two step heating superheated steam generator is developed and application of system are also discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.717-722
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• 2016

In this paper, in order to support the peak current limiting function depending on the intensity of the fault current at the early stage of failure, a two magnetically coupled type superconducting fault current limiter (SFCL) is proposed, which includes high-Tc superconducting (HTSC) element 1, where the existing primary and secondary coils are connected to one iron core in parallel, and HTSC element 2, which is connected to the tertiary winding using an additional iron core. The results of the experiments in this study confirmed that the two magnetic coupling type SFCL having coil 1 and coil 2 connected in parallel using dual iron cores is capable of having only HTSC element 1 support the burden of the peak current when a failure occurs. The reason for this is that although HTSC element 1 was quenched and malfunctioned because the instantaneous factor of the initial fault current was large, the current flowing to coil 3 did not exceed the critical current, which would otherwise cause HTSC element 2 to be quenched and not function. In order to limit the peak current upon fault through the sequential HTSC elements, the design should allow it to have the same value as the low value of coil 1 while having coil 3 possess a higher self-inductance value than coil 2. In addition, a short-circuit simulation experiment was conducted to examine and validate the current limiting and recovery characteristics of the SFCL when the winding ratio between coil 1 and coil 2 was 0.25. Through the analysis of the short-circuit tests, the current limiting and recovery characteristics in the case of the additive polarity winding was confirmed to be superior to that of the subtractive polarity winding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.5
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• pp.359-365
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• 2018

Herein, electromagnetic shielding structures to reduce the external noise coupling to printed spiral coils (PSCs) and a design method for improving the bandwidth of shielded PSCs have been proposed. It has been demonstrated that the bandwidth of shielded PSCs is limited due to the parasitic capacitance between the coils and the shielding structures and is confirmed by the transfer function simulation of the shielded PSCs with a transmission line as the radio-frequency interference noise source. A design method for the bandwidth improvement of the shielded PSCs has been proposed based on the equivalent circuit model analysis and the case studies depending on PSC designs with a three-dimensional field simulation. With the design method, an optimized shielded PSC design has been presented and successfully confirmed by experimental verification in that the optimized design results in a significant bandwidth improvement.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2219_2220
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• 2009

The characteristics of the Superconducting Magnetic Energy Storage (SMES) system are faster response, longer life time, more economical, and environment friendly than other Uninterruptible Power Supply (UPS) using battery. Fast charge and discharge time of SMES system can provide powerful performance of improving power quality in the grid. In order to demonstrate the effectiveness of SMES, the authors make a 10kJ SMES system for connection with RTDS (Real Time Digital Simulator). Because the characteristics of superconducting magnet are very important in SMES system, the necessary items such as thermal characteristic, mechanical stress and protection circuit should be considered. In this paper, the authors experimented thermal characteristics of the 10kJ SMES system. The experiment was accomplished using a simulation coils made of aluminium. It has same dimension of the 10kJ class HTS SMES coil. The coil was cooled with GM (Gifford -McMahon) cryocooler through the OFHC (Oxgen Free High thermal Conductivity) conduction bar. The test results of cool down and heat loads characteristics of the simulation coils are described in detail.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.391-400
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• 2008

Multi-pulse topology of converters using elementary six-pulse GTO - VSC (gate turn off based voltage source converter) operated under fundamental frequency switching (FFS) control is widely adopted in high power rating static synchronous compensators (STATCOM). Practically, a 48-pulse ($6{\times}8$ pulse) configuration is used with the phase angle control algorithm employing proportional and integral (PI) control methodology. These kinds of controllers, for example the ${\pm}80MVAR$ compensator at Inuyama switching station, KEPCO, Japan, employs two stages of magnetics viz. intermediate transformers (as many as VSCs) and a main coupling transformer to minimize harmonics distortion in the line and to achieve a desired operational efficiency. The magnetic circuit needs altogether nine transformers of which eight are phase shifting transformers (PST) used in the intermediate stage, each rating equal to or more than one eighth of the compensator rating, and the other one is the main coupling transformer having a power rating equal to that of the compensator. In this paper, a two-level 48-pulse ${\pm}100MVAR$ STATCOM is proposed where eight, six-pulse GTO-VSC are employed and magnetics is simplified to single-stage using four transformers of which three are PSTs and the other is a normal transformer. Thus, it reduces the magnetics to half of the value needed in the commercially available compensator. By adopting the simple PI-controllers, the model is simulated in a MATLAB environment by SimPowerSystems toolbox for voltage regulation in the transmission system. The simulation results show that the THD levels in line voltage and current are well below the limiting values specified in the IEEE Std 519-1992 for harmonic control in electrical power systems. The controller performance is observed reasonably well during capacitive and inductive modes of operation.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.4
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• pp.351-358
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• 2003

This paper describes distribution characteristics of switching surge voltage in stator windings of induction motor driven by IGBT PWM inverter. To analyze the voltage distribution between the turns and coils of stator winding, equivalent circuit model of induction motor including cable was proposed and high frequency parameter is computed by using finite-element method (FEM). From the electro-magnetic transient program (EMTP) simulation of the whole system for induction motor, feeder cable, and PWM inverter, the variable effect on rising time of the inverter, cable length, and switching frequency on the voltage distribution is also presented. In order to experiment, an induction motor, 380[V], 50[HP], with taps from one phase are built to consider the voltage distribution so that these results can be helpful when filter was designed to remove high dv/dt.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.2
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• pp.137-150
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• 1997

The problem of electromagnetic coupling into a thin conducting wire through a slot in an infinite conducting is analyzed by use of MPIE(mixed potential integral equation) and two- dimensional moment method using subsectional(rooftop) basis functions. The equivalent circuit is derived using a center-repesentation method which is valid in a narrow slot case. The equi- valent magnetic currents on the slot and the induced currents on the wire are caculated respec- tively, for the TM wave is incident upon the slot with arbitrary angle of incidence. The theoretical transmission coefficients of transmission line which is composed of thin-wire and infinite conducting plate with a narrow slot are compared and found to be in good agreement with experimental results.