Study On Digital Soft-switch Fuzzy Adaptive Arc Welding Power Source

Inverter arc welding power source becomes a hotspot in welding industry withadvantages of small, light weight, fast dynamic response, easy to implement real-timecontrol of welding process and good flexibility. However, the traditional inverter arcwelding power source has two prominent shortcomings:1) Arc welding power sourceusing analog PWM control method has temperature drift and zero drift, which limitscontrol accuracy;2) Main switch device of converter is hard-switching, which resultsin large switch losses. To solve these problems, soft-switch technology is introducedinto converter to reduce the switch loss, and fuzzy adaptive inverter arc weldingpower source combining phase-shift full bridge DC-DC soft-switch converter withdigital control is developed through using DSP and EPLD.Firstly, we review the soft-switch technology, DSP digital control technology,intelligent control theory, and their applications in inverter arc welding power source.Secondly, the principle of traditional phase-shift full bridge DC-DC soft-switchconverter is analyzed. Thirdly, a novel phase-shift full bridge DC-DC soft-switchconverter is developed to design main circuit. The MATLAB simulations of maincircuit demonstrate that the switch losses of the soft-switch converter are significantlyreduced. Through using dsPIC30F6010A+EPM7128as the core of control system,double-loop control taking the voltage feedback loop as the outer loop, and thecurrent feedback loop as the inner loop is used to keep output voltage of inverter arcwelding power source constant. Compared with traditional inverter arc welding powersource double-loop control system, the MATLAB simulations demonstrate thesuperiority of our system in terms of various performance metrics of step response.This paper mainly researches on LCL soft-switch full bridge inverter arc weldingpower source based on fuzzy PI self-correction controller. A new self-correctionsystem using voltage fuzzy PI control is developed and successfully applied tovoltage control of inverter arc welding power source. To decrease the current of maincomponent of converter, the P regulator with current peak limitation is used in thecurrent inner loop of control system. This system has good dynamic and stateperformance of voltage control and improves the welding quality.In this paper, we design sample circuit, dsPIC30F6010A control unit, drive andprotect circuit, human machine interface. After designing hardware circuit, software including control system software and human machine interface software is designedthrough mixing C language and assembly language. The experiments over theprototype of digital inverter arc welding power source verify that digital inverter arcwelding power source based on full bridge phase shift DC-DC soft-switch converterovercomes low control accuracy of analog control system and large switch losses ofhard-switch converter in traditional inverter arc welding power source. Therefore,digital inverter arc welding power source based on full bridge phase shift DC-DCsoft-switch converter can significantly improve weld quality and reduce energy losses,and has good application prospects.