Study On The Inverter MIG Welding Machine And Its Controlled System

The pulse MIG welding is a welding technology with the rapid development and widerange of applications. Its main features: welding line beautiful, low spatter, a wide range ofcurrent adjustment, good welding joint performance, achieve the all position welding. Witha pules and a drop droplet transition process at the crafts, high quality welding, the droplettransfer is very stable. The equipment of the pulse MIG welding is developing very rapidlytoo, it gradually developed from analog arc welding power source to the arc welding powersource of the microcomputer controlling,what was more, the diticized arc welding powersource.In this paper, the controlled system of pulse MIG welding machine includes: the thearc welding power source electricity converter system, the controlling system, the wirefeeder driving system. The inverter circuit of the arc welding power source has tworectifiers from AC to DC and one inverter link from DC to AC, the inverter link uses thefull bridge IGBT inverter circuit. In the controlled system, it has the system of themicrocomputer controlled、IGBT drive circuit、protection circuit and the PWM pulse widthmodulation circuit. The IGBT drive circuit is consisted of EXB841, The PWM pulse widthmodulation circuit is consisted of SG3525, and designing the current voltage conversioncircuit, the welding parameters and conditions setting and display circuit. The wire feederdriving controlled system uses a MOS control circuit and speed semi closed loop control,has braking rapidly function. The effect of the microcomputer controlled system is thecontrol of the welding parameters and welding procedures.In order to optimize the design of the system and verify the correctness of the systemdesigning, use the MATLAB software to the Welding machine control system modelingand system simulation. According to the configuration of the arc welding power source,making an assay of the transfer function of constituting link, creating the configurationdiagram of the control system. The current loop uses proportional-integral control, Theanalysis by simulation shows that The system has good performance of adaptation parameter changed, current loop has a high performance of dynamic response, its input andoutput response performance meet the requirements of the pulses controlling the pulsewelding current. The voltage loop uses proportional-integral control, The analysis bysimulation shows that voltage loop step response performance is good and meet therequirements of the welding control process.In the welding experiments, do the Aluminum welding. Through the observation ofthe weld and high-speed camera show, the droplet transition process of one droplet perpulse is stable, the welding process is stable, the welding quality is high. The process ofDC pulse MIG welding arc starting, welding, arc closing is reliable.