• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.73-80
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• 2016

The preliminary test for the dual mode plasma torch system was carried out to explore the operation properties in advance. The dual mode plasma torch system that is able to operate in transferred, non-transferred, or dual mode is very adequate for melting the mixed wastes including nonconductive materials such as concrete, asbestos, etc. since it exploits both the high efficiency of heat transfer to the melt in transferred mode and stable operation in non-transferred mode. Also, system operation including restarting is reliable and very easy. A stationary melter with a refractory structure was designed and manufactured considering the melting behavior of slags to minimize the refractory erosion. The power supply for the dual mode plasma torch system built with high power insulated gate bipolar transistor (IGBT) modules has functions for both current control and voltage control and is sufficient to suppress the harmonics during the operation of the plasma torch. The power supply provides two different voltages for transferred operation and non-transferred. It is confirmed that the operation voltage in transferred is always higher than non-transferred. The dual mode plasma torch system was successfully developed and is under operation for a melting experiment to optimize operation data.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.9
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• pp.118-125
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• 1997

This paper proposed a new partial resonant 3.PHI. AC-DC boost converter of high efficiency using lossless snubber. The proposed converter, DCM (Discontinuous Current Mode) has a merit of simple controlled circuit because the input current control discontinuously. But turned off switching loss and stress of the switching device increase when the switch turned off at the peak of current. Therefore, the paper improves efficiency by adopting the PRS$^{2}$(Partial Resonant Soft Switching) in 3.PHI. AC-DC boost converter and makes the unity power factor. The PRS$^{2}$ is reduced a current/voltage stresses of switching devices. Also, a DCMPRS$^{2}$M(Discontinuous Conduction Mode Partial Resonant Soft Switching Method) appear the current and voltage equation of this circuit. The paepr examine in a 3.PHI. AC-DC boost converter and show the result of that.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.226-233
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• 2003

The discharge characteristics of a prototype ion source was investigated, which was developed and upgraded for the NBI (Neutral Beam Injection) heating system of KSTAR (Korea Superconducting Tokamak Advanced Research). The ion source was designed for the arc discharge of magnetic bucket chamber with multi-pole cusp fields. The ion source was discharged by the emission-limited mode with the control of filament heating voltage. The maximum ion density was 4 times larger than the previous discharge controlled by a space-charge-limited mode with fully heated filament. The plasma (ion) density and arc current were proportional to the filament voltage, but the discharge efficiency was inversely proportional to the operating pressure of hydrogen gas. The maximum ion density and arc current were obtained with constant arc voltage ($80{\sim}100V$), as $8{\times}10^{11}cm^{-3}$ and 1200 A, respectively. The estimated maximum beam current was about 35 A, extracted by the accelerating voltage of 80kV.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.797-800
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• 1987

A new current control scheme is suggest.ed which is suitable for ac servo inverter drives. The scheme uses a simple block diagram to produce the reference stator voltage vector, and the vector nearest to it is chosen for switching. With the same arrangment three kinds of operation modes are possible : (1) constant rate sampling, (2) constant current deviation, (3) adaptive current deviation. In mode (1) current deviation after one period is minimized, while in mode (2) and (3) intervals between switchings are maximized.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.9
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• pp.1597-1604
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• 2016

The speed at which the SRM (Switched Reluctance Motor) makes a transition from chopping control to single pulse operation. (i.e., low speed to high speed operation). It is unsatisfied with performance at all operational regimes. In this paper, the operational performance of SRM can be improved by using current hysteresis control method. This method maintains a generally flat current waveform. At the high speed, the current chopping capability is lost due to the development of the back-EMF. Therefore SRM operates in single pulse mode. By using zero-current switching and zero-voltage switching technique, the stress of power switches can be reduce in chopping mode. When the commutation from one phase winding to another phase winding, the current can be zero as fast as possible in this period because several times negative voltage of DC-source voltage produce in phase winding. This paper is compared to performance based on energy efficient C-dump converter topology and the proposed resonant C-dump converter topology. Simulation and experimental results are presented to verify the effectiveness of the proposed circuit.

• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.30-38
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• 2023

In this paper, a constant current(CC) and constant voltage(CV) control method using a primary-side regulated(PSR) fly-buck converter is proposed. Because the primary-side structure of the fly-buck converter is the same as that of the synchronous buck converter, it always operates in continuous conduction mode(CCM). Therefore, in the proposed method, the load information on the secondary side can always be easily estimated by measuring the primary inductor current at the midpoint of the switch-on period. An accurate CC/CV control can be achieved through simple calculations based on this estimated information. Consequently, the proposed method is advantageous for optimizing the control performance of the PSR converter. The validity of the proposed control was verified using a 5 W prototype of a PSR fly-buck converter. The experimental results confirmed that the current reference of 500 mA was followed within the error range of 1.2%, and that the voltage reference of 12 V was followed within the error range of 1.8% despite the indirect control of the load current and output voltage from the primary side.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.373-377
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• 1996

Recently, active power factor control for AC/DC converter has been required to replace for a conventional diode rectifier. A voltage type AC/DC converter is widely used to obtain higher regulated DC voltage than input voltage with a unity power factor and a sinusoidal line current. This paper describes several active power factor control method for AC/DC converter. The analysis of several active power factor control is given. The simulations for hysteresis control, peak current control. constant frequency control and average current mode control are represented and compared.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.182-192
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• 2015

This study develops a digital control scheme with power factor correction for a front-end converter in an electric vehicle battery charger. The front-end converter acts as the boost-type switching-mode rectifier. The converter assumes the two roles of the battery charger, which include power factor control and robust charging performance. The proposed control scheme consists of a charging control algorithm and a grid current control algorithm. The scheme aims to obtain unity input power factor and robust performance. Based on the linear average model of the converter, a constant-current constant-voltage charging control algorithm that passes through only one proportional-integral controller and a current feed-forward path is proposed. In the current control algorithm, we utilized a second band pass filter, a single-phase phase-locked loop technique, and a duty-ratio feed-forward term to control the grid current to be in phase with the grid voltage and achieve pure sinusoidal waveform. Simulations and experiments were conducted to verify the effectiveness of the proposed control scheme, both simulations and experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.505-514
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• 1994

Koreasat spacecraft requires accurate and reliable attitude control to provide beam pointing for tenyear long communication and direction broadcasting services. This paper describes the detailed design and performance of an on-orbit normal mode attitude control subsystem for the spacecraft. Koreasat used a momentum wheel which has nominal momentum 475in-1b sec(547.6cm-kg sec) aligned with the pitch axis to control pitch attitude and provide gyroscopic stiffness in roll/yaw plane and used a 300 atm magnetic torquer to control the roll and yaw attitudes. An Earth Sensor Assembly (ESA) is used to provide pitch and roll information for the on-board micropocessor. The roll/yaw control used bang-off-bang control and while pitch axis control used proportional and integral control law. Control system errors during the operational normal mode are 0.03 deg, 0.1 deg and 0.01 deg in roll, yaw and pitch axes, respectively. Current attitude control system provides adequate control performances to capture initial attitude errors and spacecraft nutation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.108.6-108
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• 2001

The basic circuit block diagram of CMOS current mode sum and subtract circuit is present in this paper. The purpose circuit consists of the invert current circuit and the basic current mirror. The outputs of the circuit are the summing of the both input current [lx+ly] and also the subtract of the both input current [lx+(-ly)]. The SPICE simulation results of the electrical characteristics with level 7 (BSIM3 model version 3.1) MOSFET transistor model of the circuit such as the input dynamic range, the frequency response and some system application have been shown and analyzed.