• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.10
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• pp.571-578
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• 1999

Current waveform control of pulse MAG welding power source is studied so that welding of thin plates may obtain high speed and improved performance. In this paper, waveform control method is proposed, digital controller using DSP is able to control the current waveform precisely. High speed welding of thin plates using pulse MAG welding method is made possible. Performance test for 1.2mm thin plates is carried out, output waveform and welding performance is analyzed.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.120-126
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• 2013

The main aim of this paper is to expound high-efficiency operation of Switched Reluctance Generator (SRG) based on the current waveform. For this purpose, theoretical analysis of the copper loss and iron loss of the system is done first. Then, necessary simulation is done to find the variation trend of the copper loss and iron loss with the variation of the current waveform at the same output power. Finally, the best current waveform which can make the system operate with high efficiency is obtained by considering the influence of these two kinds of loss. In order to verity the simulation results, the experimental platform of DC motor-SRG is built and the modified angle position control (APC) method which can specify the current shape optionally is presented. By comparing the system efficiency at the three kinds of typical current waveform, the correctness and feasibility of the theory is verified. The proposed method is simple, reliable, and easy to achieve.

• Journal of Welding and Joining
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• v.32 no.2
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• pp.70-75
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• 2014

In automotive industry, applying of Mg alloy to autobody has been issued recently as a light metal. But poor resistance spot weldability of Mg alloy is blocking commercialization. So studies on improving resistance spot weldability of Mg alloy is increasing continuously. For reduce loss of heat input during welding, inverter DC power source is considered because of short rise time to target welding current. But rapid rising of welding current can increase temperature rapidly in nugget and oxide film between electrode and base metal, and that causes generating expulsion on low welding current range. In this study, for increase optimum welding current range and prevent generating expulsion, applicate various types of welding current waveform controls during resistance spot welding. For analysis effects of each current waveform control, acceptable welding current regions according to electrode force and welding time is determined and lobe diagram is derived. In result, pre heat is proposed as optimum type of welding current waveform control.

• Journal of Welding and Joining
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• v.19 no.6
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• pp.643-651
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• 2001

A new waveform control technique has been developed for suppressing the spatter generation in the repelled transfer mode of high current $CO_2$ welding. Based on the spatters in repelled transfer, a waveform concept of concept was established in a way to drop the welding current to lower level right before the pendant weld drop detatchment so that the explosion force associating with drop detatchment was decreased. There were several variables to be controlled such as the moment of current drop, the base current and the time of retention at the base current. Either at lower base current or at longer retention time, the more instantaneous shot circuits were int개duced and thus the spatter generation rates were increased. With optimizing the control variables, the amount of spatter generated was decreased by about 30%.

• Journal of Welding and Joining
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• v.34 no.3
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• pp.40-46
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• 2016

The digital controlled SMA welding power source having the hot start current and short circuit waveform control was developed. The inverter power controller was used an analog circuit and the short circuit waveform controller was developed using a 8-bit MCU. For the evaluation of the developed SMA welding power source it were compared with a domestic welding power sources. Using the high titanium oxide type and low hydrogen type electrodes, the characteristics of hot start and short circuit was evaluated. Developed SMA welding power source shows good start performance. Also, arc stability and low current weldability were improved by the short circuit waveform control.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.259-266
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• 1987

In order to drive motor control system precisely, the motor is to be controlled by mmfs and current with sinusoidal waveforms. In this paper the Delta Modulation (DM) Technique is used for generating PWM pulse with sinusoidal waveform. However the motor currents yet contain odd harmonics due to leakage inductances, speed and exitation. To reduce harmonics, the parameter adaptive control method is introduced. That is, Req.C parameter of Delta Modulator is controlled adaptively by parameter adaptor. The adaptive signal is achieved by the difference between motor current and reference waveform, and this signal is converted to the voltage commend signal by adaptive mechanism. The test reslts show that this system is operated smoothly over a wide range of motor speed and motor current is controlled to be sinusoidal waveform adaptively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.15-26
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• 2008

This paper proposes a new sinusoidal rectifier which improves input factor and input current waveform without complicated switching modulation such as pulse width or a complicated feed back control. The proposed rectifier consists of a pair of capacitors connected in series, a full bridge diode rectifier, a pair of inductors, and a pair of switching devices connected in series. While the configuration of the sinusoidal rectifier is simple in itself, it effectively reduces the reactive power and harmonics involved(IEC555-2 SC77A90 Class C) in input line current. The excellent properties of the new sinusoidal rectifier are verified by theoretical analysis and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.257-263
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• 1999

Recently the performance of CO2 arc welding machine has been advanced significantly through the adoption of inverter circuit topology which made it possible to control the waveform of welding current and thus to suppress the spatter generation. However, the optimum waveform is still uncertain. As a first step for figuring out the promising waveforms, this study was performed to set-up the experimental system for studying the effect of waveform variables, The system designed in this study is a digital controller using single chip microprocessor of 80C196KC. As a result of performance test of this system, it was demonstrated all of the waveform variables could be set individually and the resultant waveforms appeared to be pretty much the same as the intended one.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.51-57
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• 2003

The metal transfer in $CO_2$ welding shows the transition of transfer mode from short-circuiting to repelled transfer will the increase of welding current. While the short-circuiting mode in $CO_2$ welding has been studied very extensively relating with droplet formation and spatter generation, the repelled transfer has little been understood. In this study, high current $CO_2$ welding has been performed with bead-on-plate welds along with the waveform analyzer and high speed camera. The image of high speed camera was synchronized with its waveform so that the moment of spatter generation could be realized during drop detachment. As a results of this study, it was found that welding arc changes its location either once or three times and thus single or double pulse signals were developed in the voltage waveform. Whenever the arc moved its location, new arc was developed in a explosive way and thus it caused spatter generation. Specially severe spattering took place when the waveform showed a double-peak pattern. As a consequence of these results, new waveform control techniques could be suggested for suppressing the spatter generation in the high-current $CO_2$ welding.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.581-586
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• 2000

Gas metal arc welding(GMAW) uses a continuously fed electrode as a filler metal. The arc is shielded from atmospheric contamination by an inert gas active or inert/active gas mixture delivered through the welding gun and cable assembly. The recent research topics on $CO_2$ are welding machines are focused mainly on the reduction method of generated spatter by using new type consumable electrode metal or inverter control method. The various current waveform control methods have been researched for welding performance improvement. Until now current waveform control methods reduce to spatter occurred by instantaneous short circuiting,. but these methods is drawback that no reduce spatter occurred by arc reignition. In this paper the previous arc reignition current control method for welding performance improvement of inverter arc welding machine is studied and compared the various current control methods with the previous arc reignition current control method.