| To build an efficient carbon dioxide (CO2) welding power resource with excellent property, the inversion technology is applied to design the main circuit, the control circuit and the driver circuit. The full bridge structure is used in main circuit in order to reinforce the power provided by the CO2 welder. The parameters of the power components including IGBT and transformer are carefully calculated, and the means of protection of IGBT (Insulted Gate Bipolar Transistor) is specially analyzed. Both the control of PWM (Pulse Width Modulation) generated by chip SG3526 and the closed-loop circuit with the negative feedback by voltage is applied to create strong static feature of the CO2 welder, which make its voltage stable when its load is changing. The block diagram and mathematical model of the system are built for the simulation by the software MATLAB, and the result of the simulation aids the designing of an electrical inductor, which can control the dynamic feature of the CO2 welder. The idea of controlling the current waveform by means of switching the current closed-loop or the voltage close-loop in different circuit state is brought out. The hardware and software of the microcomputer system are designed in order to control the welding process automatically. The driver circuit with pulse transformer has trouble to be made or adjusted, so the driver circuit used of photoelectric coupler is designed and made. By analyzing the current and voltage waveforms from the IGBT and the output of the CO2 welder in the tests, the conclusions have been drawn that the structure of the main circuit is valid and the components used in the main circuit are credible. In the end, the circuit of feeding wire of consistent velocity based on the technology of PWM is designed and tested in the experiment. The results of the experiment meet the standard of JB/T9533-1999.
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