• Journal of Welding and Joining
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• v.28 no.5
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• pp.99-105
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• 2010

Inverter DC resistance spot welding process has been very widely used for joining such as automotive body sheet metal. Because the lobe area of DC welding is larger than AC welding and DC welding has low electrode wear. So the use of Inverter DC resistance spot welding process has been further increased. And the application of high tensile steel is growing for light weight vehicle. To improve the weldability of high strength steel, the development of Inverter DC resistance spot welding system is more conducted. However, Inverter DC resistance spot welding system has a few problems. Current waveform is unstable and the expulsion has been occurred by characteristics of steel. In this study, inverter DC resistance spot welding system was made. And Fuzzy control algorithm was applied for constant current. The genetic algorithm was applied to optimize the fuzzy scaling factors, in order to optimize the fuzzy control.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.45-53
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• 2003

For the improvement of welding performance, high-efficiency inverter system was designed and applied that system to the conventional large scale Flashbutt welder. The inverter systems are consists of full bridge PWM power control system and DSP controller. This inverter system has increased switching frequency of power control system of Flashbutt welder. For the test of application effects, we compared an our inverter control system with a conventional thyristor control system. In the results, we confirmed that our system has decreased the welding spatter amouts and improved welding performance.

• Journal of Power Electronics
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• v.2 no.2
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• pp.124-129
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• 2002

Invertigation electromagnetic emissione of inverter power sources resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, sunbber circuits and constructional aspect exert a great influence on the conducted emission welding inverters.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.172-174
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• 2006

Nowadays, a Spot Welding system has been widely used in all kinds of industries and the common control method of the systeme is a simple current control using SCR. But, that kind of system is less effective than a current control method using inverter. So, it is constantly proposed that an improvement of hard ware and control method of spot welding system in compliance with technological advancement in power electronics. This paper deals with spot welding system using inverter. Especially, it deals with hard ware structure, features and output characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.12-17
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• 2000

IN induction heating system the high frequency operation allows a rapid response to current fluctuation in the inverter and result in improved welding quality. To work induction heating of nonferrous metals, a welding power supply is need high working frequency and high power. This paper is shown design technique for increasing working frequency in induction heating for welding coppers. A series-parallel resonate inverter consists of H-type bridges, each of whose arms is composed of a combination of two parallel IGBTs. Inverter operating with the fixed frequency is controlled by pulse width modulation (PWM). As switching adapted the Zero-Voltage Switching technique to reduce switching losses the system is high efficiency. The propose inverter has feature which is high efficiency for very wide load variations with a narrow range of duty cycle ratio control and load short circuit capability. Detailed experimental results obtained from a 48[V] output, 500[W] experimental inverter are presented to verify the concept.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.4
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• pp.103-110
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• 1995

Fuzzy theory is recently finding wide popularity in various applications that include management, economics, medicine and process control system. This paper describes application of fuzzy logic in a current control system that use a inverter welding machine. The Fuzzy control is then extended to the current loop control, replacing the conventional proportional-integral(PI) control methods. The fuzzy control algorithms have been developed in detail and verified by experiments of a inverter welding system. The experimentation study indicates the superiority of fuzzy control over the I control methods. Fuzzy control seems to have a lot of promise in the applications of welding process control system.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.76-83
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• 2010

The purpose of this study is to propose a method to decide near-optimal settings of the constant current fuzzy control parameters using a controlled random search. This method tries to find the near-optimal settings of the constant current fuzzy control parameters through experiments. It has an advantage of being able to carry out searches in the search domain which includes some irregular points. The method suggested in this study was used to determine the fuzzy control parameters by which the desired welding current were formed during inverter DC resistance spot welding. The output variable was the ITAE (integral of time multiplied by the absolute error). This output variable was determined according to the input variables, which are the GE, GDE, and GDU. This study described how to obtained near-optimal welding current condition over a wide search space conducting a relatively small number of experiments.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.180-184
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• 1998

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 overal system is controlled 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 generated spatter is reduced compare to conventional inverter arc welding machine.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1012-1016
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• 1998

According to the adoption of inverter circuit topology for welding machine area, the improvement of welding performance can be achieved. However conventional CO2 inverter arc welding machine uses the constant voltage characteristics. So the metal transfer is performed under unoptimum condition in the sence of spatter generation. In this paper the new control algorithm is proposed for welding machine, which is the instantaneous output current control method using single chip microprocessor. But the optimum waveform of welding current is still uncertain, as a first step for figuring out the optimized waveforms, this study was performed. And as a result of performance test of the proposed system, it was demonstrated that all of the waveform variation parameter could be set individually and the generated spatter is reduced compared to conventional inverter arc welding machine.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.5
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• pp.397-406
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• 2003

Resistance spot welding is widely employed in a manufacturing process. In recent years, the requirement for more sophisticated quality control procedures has been in mass production industries. The requirements for high productivity and better weld qualities have lead to the development of more widely available microcomputer-based control. In this study, the inverter type power source and welding servo gun are developed. As the results, we have some advantages over the previous methods such as pneumatic gun. One of them is that the precise pressure control can be attained during the welding process. In addition, production time and cost can be decreased.