• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.13-18
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• 2011

More and all-electric aircraft (AEA) carry many loads with varied functions. In particular, there may be large pulsed loads with short duty ratios which can affect the normal operation of other loads. In this paper, a converter with spilt capacitors and an improved adaptive controller is used as the Voltage Bus Conditioner (VBC) with the reduced capacitive storage to mitigate the voltage transients on the bus. The proposed converter allows the smaller capacitive storage. Also, the proposed controller has the advantage of requiring only one sensor and performing both the functions of mitigating the voltage bus transients and maintaining the level of energy stored. Experimental results are presented which verify the control principles and demonstrate the practicality of the approach.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1154-1161
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• 2015

This paper presents a semi-lumped balun transformer using conventional PCB process and its design theory and geometry for the maximally flat response and wide bandwidth using magnetically coupled LC resonators. The proposed balun is comprised of two pairs of coupled resonators which share one among three LC resonators. It provides an identical magnitude and phase difference of 180° between two balanced ports with DC isolation and an impedance transformation characteristic. Theoretical design and analysis were performed to optimize the inductance and capacitance values of proposed balun device for obtaining the wide bandwidth and maximally flat response in its pass-band. Three balun transformers with a center frequency of 500 MHz were demonstrated for proving the concept of design proposed. They were fabricated by using lumped chip capacitors and planar inductors embedded into a conventional 4-layered PCB substrate. They exhibited a maximum magnitude difference of 0.8 dB and phase difference within 2.4 degrees.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1156-1157
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• 2008

The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about 205 $C/m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}$ = 2.5 V, while the positively charged density became the maximum, about 61.1 $C/m^3$ at the region where it was located around the cathode layer. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1382-1390
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• 2017

This paper presents a power supply for gate drivers, which uses a magnetic resonance wireless power transfer system. Unlike other methods where multiple antennas are used to supply power for the gate drivers, the proposed method uses a single antenna in an insulated receiver to make multiple mutually isolated power supplies. The power transmitted via single antenna is distributed to multiple power supplies for gate drivers through resonant capacitors connected in parallel that also block DC bias. This approach has many advantages over other methods, where each gate driver needs to be supplied with power using multiple receiver antennas. The proposed method will therefore lead to a reduction in production costs and circuit area. Because the proposed circuit uses a high resonance frequency of 6.78 MHz, it is possible to implement a transmitter and a receiver using a small-sized spiral printed-circuit-board-type antenna. This paper used a single phase-leg circuit configuration to experimentally verify the performance characteristics of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.7
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• pp.323-331
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• 2000

Recently Advanced Static Var Compensators(ASVC) or STATic Synchronous COMpesator(STATCOM) has been considered as a next generation reactive power controller. The STATCOM is a voltage source inverter(VSI) based on the static VAr compensator with only small capacitors on the dc side. The main function of the STATCOM is to keep the bus voltage magnitude at the desired value. This paper compared the PAM STATCOM with the PWM STATCOM. The characteristics and the control method of each model is analyzed. And the simulation of STATCOMs based on the above two methods is presented.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.1
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• pp.3-8
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• 1987

The conventional autosequentially commutated current-fed inverter (ASCI) is widely employed with the induction motor drives for speed control. Howener, this inverter has a limit of high power and high frequency indution motor drives. One of the limitations is to be found in the commutation capacitors in the main circuit of this inverter. A new current-fed gate turn-off thyristor (GTO) inverter is developed. This inverter is composed of the main GTO bridge configuration and the improved energy rebound circuit (ERC)without the commutation capacitor. This inverter works stable at high frequency from light load to heavy one. The improved ERC is used not only to rebound the load reactive power to the dc link, but also to return the power in the load to the ac source. The new GTO inverter circuit and the characteristics of the inverter induction motor drives are explained and analyzed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.5
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• pp.231-237
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• 2005

Many conventional multi-level inverters have detected switching faults by using the over voltage and current. However, fault detection of the switching elements is very difficult because the voltage and current due to each switching fault decrease more than the normal operation. Moreover, the dc-link unbalancing voltage causes a serious problem in the safety and reliability of system when the 3-level inverter faults occur Therefore, this paper proposes the simple fault diagnose method and the neutral-point-voltage control method that can protect the 3-level inverter system from the unbalancing voltage of the do-link capacitors when the faults of switching elements occur in the 3-level inverter that is very efficient in ac motor drives of the high voltage and high power applications. Through experiment results, the validity of the proposed method is demonstrated.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.201-204
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• 2008

The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about 205 C/$m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}$ = 2.5 V, while the positively charged density became the maximum, about 61.1 C/$m^3$ at the region where it was located around the cathode layer. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.1-2
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• 2013

In this paper, we inject input currents having $3^{rd}$ harmonic to reduce the capacitance of DC link capacitors in single-phase converters. If the input current with third harmonic is injected, the required capacitance can be reduced by minimizing the difference between the input and output power. To control the input current, instead of PI control done in rotating frame, PR controller is used with the proposed separate current control method for fundamental and $3^{rd}$ harmonic components. The validity of the proposed method has been demonstrated by simulation results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.286-291
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• 2003

(Pb,Sr)TiO$_3$(PST) thin films have attracted great interest as new dielectric materials of capacitors for Gbit dynamic random access memories. In this study, inductively coupled CF$_4$/Ar plasma was used to etch PST thin films. The maximum etch rate of PST thin films was 740 $\AA$/min at a CF$_4$(20 %)/Ar(80 %) 9as mixing ratio, an RF power of 800 W, a DC bias voltage of -200 V, a total gas flow of 20 sccm, and a chamber pressure of 15 mTorr. To clarify the etching mechanism, the residue on the surface of the etched PST thin films was investigated by X-ray photoelectron spectroscopy. It was found that Pb was mainly removed by physically assisted chemical etching. Sputter etching was effective in the etching of Sr than the chemical reaction of F with Sr, while Ti can almost removed by chemical reaction.