Study On MIG400 Digital Inverter Welding Machine

The development of inverter welding power plays an important role in reducing the weight and volume of the welding equipment.There are lots of problems in the traditional analog control mode,such as low precision,slow response,poor anti-interference performance,and single function.The design of digital inverter pulse MIG welding power which took the MIG welding as its core,based on the study of the development status and trend of the digital welding power source domestic and abroad,and the characteristics of the digital signal processing technology.The first part of this article is the design scheme of the welding power,which including the comparison of several commonly used in the main circuit topology,selects the IGBT full bridge soft switching inverter topology,consisting of input rectifier filter circuit,inverter circuit,frequency transformer,output rectifier circuit and output,reactor.The discussion is focus on the design of soft switch,analyzed the principle and characteristics of phase shift resonant soft switching,calculated the parameters of meeting the working state of the capacitor and inductor and resonant components.Then,the other part components of the main circuit the were calculated and selected.The control circuit is designed with digital signal processor TMS320F28335 as the core.The article elaborated the function,the working principle and specific the circuits of the DPS minimum system,the ADC circuit,the serial communication circuit and the protection circuit.The IGBT driving circuit was designed with transformer isolation mode.The control circuit IGBT was controlled by control circle through of using the pulse width modulation(PWM)mode.The F28335 generated two groups of dead zone PWM pulse waveform whose phase difference is 180°.Control the IGBT turn-on or turn off after of power amplification and isolation by the drive circuit.The design of the control system program of DSP includes main program,welding subroutines,condition control program of the PI algorithm,and the arc voltage feedback loop control procedure etc.Finally,the experiments of the main circuit of the full bridge inverter soft switch were carried out.The main power switch and transformer waveform were gathered and analyzed under the conditions of no-load,light load and heavy load.Through the experiment of the control system based on DSP,the different duty of driving waveform ratio were obtained.The welding technology experiments on the MIG400 were carried out,and the results were analyzed.The test result shows that,the main circuit of the welder has a fast response speed,the hardware circuit is simple and reliable,the system software is highly efficient and strong anti-interference ability.The results achieved the original design concept and requirements basically.