• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.154-157
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• 1998

In this paper, the inverter TIG(Tungsten Inert Gas) welding system with high power efficiency by means of pulse current control of welding process is presented. In TIG welding, pulse current control is utilized in order to attain less apatter and high welding performance. The four factors which determine the welding performance of the pulse current are frequency, base current, peak current, and peak current duty current, and peak current duty ratio. In this paper, we analyze these factors should be controlled to achieve minimum power input. To demonstrate the practical significance of our results, we present some experimental results as well as simulation results.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.558-562
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• 1999

In this paper, the inverter spot welding system with high efficiency via an instantaneous power control is presented. In spot welding, instantaneous power control is utilized in order to attain less spatter and high welding performance. Also we proposed a PI controller for spot welder system using Evolution Strategy(ES) with varying search space. ES with varying search space which depends on fitness values at each generation is used to tune PI control parameters

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.376-379
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• 1993

GoldStar Industrial Systems Co. R & D center successfully developed the inverter for welding under the support of GoldStar Electric Machinery Co. Now, we are currently working on the mechanical part of articulated robot and a high-performance general purpose motion controller. By combining the above three items, we will be able to constitute the complete welding robot system on our own. In this article. the welding robot system currently under developing is introduced. The main focus will be placed on the development of general purpose motion controller with welding control module. Therefore, the architecture of welding robot controller where the general purpose motion controller is combined with the welding controller module will be explained. Here, the software system will be explained with regard to the hardware system.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.102-107
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• 2014

SCR(Thyristor) type $CO_2$ welders have widely used for the welding process of heavy industries such as shipbuilding and plant. Since the industrial fields of shipbuilding and plant are usually exposed to severe welding condition with lots of dust, extreme temperature, high humidity and vibration, it is not recommended to use inverter type welder despite its state-of-the-art technology. Many sophisticated functions in the inverter welder may not work due to malfunction of its sensitive components. Hence this study focused on digitalization of SCR $CO_2$ welder by making use of microprocessor for SCR phase control. By this application, fine control of output of the $CO_2$ welding systems is achieved. Also pulse output mode of operation is realized and its verification is carried out with aluminum sample welding. The experimental results showed sound weld bead. The front operation panel provide user with numerical parameter settings and monitors. It will help precise weld process monitoring and control with digital value.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.481-490
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• 2021

In the ultrasonic welding machine, when the load fluctuates, the L and C of the piezo element in the oscillation part change. As a result, the resonant frequency is changed, so it is necessary to match the operating frequency of the ultrasonic welding machine to the new resonant frequency. That is, in order to maximize the output of the oscillation unit of the ultrasonic welding machine, it is inevitable to follow the resonance frequency. Accordingly, many methods for following the resonant frequency are being actively studied. In addition, in order to check the effect of external inductance on the operation of the ultrasonic welding machine, The equivalent circuit of the piezo element was analyzed by including the external inductance for resonance in the equivalent circuit of the piezo element, and the method of selecting an appropriate inductance was described. In this paper, we propose a new system that allows the switching frequency of the inverter to tracking the resonance frequency even if the resonance frequency is changed due to the load of the ultrasonic welding machine.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.7
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• pp.103-108
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• 1998

In this paper, we atempt to control the nonlinear power system for resistance spot welders to be a fully linearizesd system by applying the recently developed nonlinear feedback linearization techniques. the controller proposed in this paper is computationally simple. In addition, the easy gain tuning as well as the high dynamic performance of resistance spot welding systems can be obained simulaneously. To illustrate the dynamic performance of our controller further, we present some simulation results.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.563-568
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• 1999

Generally the control method of wire feeding motor in welding machine has been used full-wave phase control method. The fire-angle control generates low frequency speed ripple, and it causes the output current ripple. So it results in the variation of welding condition and low welding performances such as spatter generation and bead state. For the purpose of welding performances improvement by speed controller in wire feeding motor, in this paper the constant speed control method for welding machine is proposed. The proposed system is composed of speed control loop and current control loop. As a result of experiment by using proposed constant wire feed experiment by using proposed constant wire feed speed controller, the output voltage and current waveform and metal transfer are maintained stably. And moreover the number of instantaneous short circuit occurrence is reduced remarkably.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.260-264
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• 1998

Three phase Boost/Buck converter which have economical merits and simple control scheme, are analyzed and evaluated through comparative methods and digital simulation for equivalent load. Those play a part of voltage boost/buck as well as power factor correction with single switch. Controller operating in constant and variable frequency is used for rapid output response and stable system condition respectively. Moreover low THD property of single switched converters is available for inverter arc welding machine known as high power and low power factor. So, in this paper a comparison of the characteristics in boost and buck converter is described and then simulation results conforms the merits from point of view of power factor and voltage regulator.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.384-394
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• 2002

In this paper, a new control strategy is proposed to improve the quality of the welding products. The conventional nonlinear power control system of spot welders is linearized using nonlinear feedback linearization technique based on differential geometry theory. An evolution strategy(ES) geometry is used to find optimal gain of PI controllers. It tries to find out the optimal control parameters by imitating the natural evolution. Some Simulation and experimental results show that the proposed variable power control system using ES algorithm has better dynamic performances than the conventional one.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.69-74
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• 2001

In this Paper are described the indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter which can operate in the frequency range from 20kHz to 50kHz. A specially designed induction heater, which is composed of laminated stainless assembly with many tiny holes and interconnected spot welding points between stainless plates, is inserted into the ceramic type vessel with external working coil. This working coil is connected to the inverter and turbulence fluid through this induction heater to moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.