• 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.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.275-282
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• 1999

This paper presents the current-fed inverter of a TGV-K traction system with thyristor switches using phase control and commutation techniques. The current-fed inverters have two modes of operation which consist of forced commutation and natural commutation. In forced commutation mode, at speed of less than 120km/h, commutation is forced by means of the commutation capacitors and the thyristors. Above 120km/h, the thyristors operate in natural commutation mode, according to the voltages between phases of the motors. In this paper, the power conversion theory of the TGV-K traction system and the control principle of the converter and current-fed inverter are discussed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.4
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• pp.41-46
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• 1983

The current-fed DC-DC converter has only one energy storage reactor in series with the input for any number of outputs and is insensitive to transformer volt-second unbalance. It is considered that these properties of the converter are considerable advantages over other maltiple-output circuits. The steady-state and dynamic characteristic and stability for the current-fed DC-DC con-verter are analyzed in detail. The analysis is carried out by the state-space averaging method for the operation with the duty ratio less than 50% and is confirmed by the experiment. From the evaluation of stability it is identified that the stability of this converter is excellent as compared with that of the conventional buck type converter.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.6
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• pp.451-457
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• 1989

The current-fed DC-DC converter, which is known as the most stable DC-DC converter, has a two-winding reactor in series with the input. In this paper a new double-output DC-DC converter circuit, in which the 2nd winding of the reactor is creating the 2nd output, while the 2nd winding is feeding the energy to the input in the current-fed converter, is propose. The steady state characteristics of the new circuit are clarified and it is found that the maximum value exists in the 2nd output. Furthermore, regulation characteristic is analysed by 'Slope method' and the result shows good agreement with experimental value. The 2nd output voltage regulation is performed by using regulation IC. As a result, we have achieved good regulation characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.261-268
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• 2020

Transformer saturation in full bridge (FB) isolated DC-DC converters is caused by uneven switching speeds and voltage drops in semiconductor devices and mismatched gate signals. In order to prevent transformer saturation, most popular and widely used approach is to insert a capacitor in series with the transformer windings. This study conducts extensive analyses on transformer saturation and the effect of DC blocking capacitors when they are placed in the primary or secondary windings of a transformer. The effect of the DC blocking capacitors is verified in voltage-fed and current-fed FB converters.

• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.3
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• pp.12-23
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• 1969

In this paper, the current distribution on a 6 points fed linear antenna is theoretically introduced. The antenna that we call the 6 points fed linear antenna is an antenna which are fed by emf E1 at the first two points, emf E2 at the second two points, and emf E3 at the third two points. symmetrical with respect to the center. In this analysis, Hallens theory has been extended with the approximation in the same order.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.66-73
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• 1999

In this paper, the design of one-chip FED system integrated with driving circuits in reported on the basis of MOSFET controlled FEA (MCFEA). To integrate a MOSFET with a FEA efficiently, a new fabrication process is proposed. It is confirmed that the MOSFET with threshold voltage of about 2volts controls the FEA emission current up to 20 ${\mu}$A by applying driving voltage of 15 volts, which is enough current level to utilize the MCFEA as a pixel for FED. The drain breakdown voltage of the MOSFET is measured to be 70 volts, which is also high enough for 60 volt operation of FED. The circuits for row and column driver are designed stressing on saving area, reducing malfunction probability and consuming low power to maximize the merit of on-chip driving circuits. Dynamic logic concept and bootstrap capacitors are used to meet these requirements. By integrating the driving circuit with FEA, the number of external I/O lines can be less than 20, irrespectively of the number of pixels.

• Journal of Power Electronics
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• v.14 no.5
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• pp.989-999
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• 2014

High-performance Current Source Inverter (CSI)-fed, variable speed alternating current drives are prepared for various industrial applications. CSI-fed Induction Motor (IM) drives are managed by using different control methods. Noteworthy methods include scalar Control (V/f), Input-Output Linearization (IOL) control, Field-Oriented Control (FOC), and Direct Torque Control (DTC). The objective of this work is to compare the dynamic performance of the aforementioned drive control methods for CSI-fed IM drives. The dynamic performance results of the proposed drives are individually analyzed through sensitivity tests. The tests selected for the comparison are step changes in the reference speed and torque of the motor drive. The operation and performance of different vector control methods are verified through simulations with MATLAB/Simulink and experimental results.

• Journal of Power Electronics
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• v.4 no.4
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• pp.246-255
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• 2004

Ac-dc PWM single-stage converters that integrate the PFC and dc-dc conversion functions in a single switching converter have been proposed to try to minimize the cost and complexity associated with implementing two separate and independent switch-mode converters. In this paper, two simple ac-dc single-stage PWM full-bridge converters are considered - one current-fed, the other voltage-fed. The operation of both converters is explained and their properties are noted. Experimental results obtained from simple lab prototypes of both converters are presented, then compared and discussed.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.755-760
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• 2003

A novel current-fed energy-recovery sustaining driver (CFERSD) for a PDP is proposed in this paper. Its main idea is to recover the energy stored in the PDP or to inject the input source energy to the PDP by using the current source built-up in the energy recovery inductor. This method provides zero-voltage-switching (ZVS) of all main power switches, the reduction of EMI, and more improved operational voltage margins with the aid of the discharge current compensation. In addition, since the current flowing through the energy recovery inductor can compensate the plasma discharge current flowing through the conducting power switches, the current stress through all main power switches can be considerably reduced. Furthermore, it features a low conduction loss and fast transient time. Operations, features and design considerations are presented and verified experimentally on a 1020X106mm sized PDP, 50kHz-switching frequency, and sustaining voltage 140V based prototype.