Study On DSP-based Soft-switch Welding Power Control System

The development of welding process research, welding automation and flexible welding manufacture system has raised an ever-increasing requirement for precision and the flexible control of the welding power source. According to the characteristics of digital signal processing, the digitalization of welding inverter and its future development on the basis of DSP's basic characteristics are introduced. Firstly, the development, control principle, characteristics and chip selection of DSP are introduced in the paper. The paper focuses on component part of digital pulse MIG welding inverter power. Main circuit, control circuit, pulse width modulation (PWM) circuit, drive circuit and wire feeding circuit are respectively analyzed. Furthermore, the software and hardware aspects are also addressed.This paper researches the main circuit of the full bridge high power soft-switching. Nowadays, welding machines usually use the hard-switching, which causes the problems of higher energy loss and lower efficiency. The problem is much more critical when the inverter frequency is high. In a welding machine, the main circuit with the technology of the soft-switching is much more ideal than the hard-switching. By the theory of the soft-switching, with the help of the simulation software MATLAB/SIMULINK, this paper analyzes the main circuit of the full bridge shift-phased zero voltage zero current(ZVZCS) soft-switching. Then, the paper gives the on and off theory of the soft-switching, the model of the main circuit, key point and the parameters of the design.The circumstance of simulation is necessary for designing DSP system. The paper illuminates DSP develop circumstance CCS2.0. The System software is coded with assemble language and designed by Modular approach. This paper introduces the main program, interrupt service procedures and routines of the function and structure in detail.Besides, a variety of anti-interference designs about both hardware and software are accomplished, so reliability of system is increased prominently.Finally, simulations are done for the PI control method. Comparing the change of response speed with dynamic parameters through increasing PI regulator and without it .That shows the technology of intelligent control plays a key role in the full bridge soft-switching power, and the system has good control efficiency.