Development Of Portable SMAW Inverter Welding Machine

The traditional arc welding equipment is large in volume and low in efficiency,which results in a great waste of energy and environmental pollution.Inverter arc welding power supply has become the trend of arc welding power supply because of its small size,light weight,high efficiency and energy saving.Shielded metal arc welding machine has the advantages of flexible operation,strong applicability,suitable for all-position welding and no need for protective gas.It is especially suitable for home maintenance,decoration and field construction.It is of great significance to make the welding machine as light and portable as possible.It can make the welding machine step by step into the family,promote the export of the welding machine and the development of the whole welding machine industry.In this paper,a lightweight and portable SMAW inverter welding machine is designed.The design of welding machine is composed of main circuit,control circuit and control power supply circuit.The main circuit design includes input rectifier filter circuit,half bridge inverter,main transformer design and output rectifier circuit design.Through detailed analysis and simulation experiments,the rectifier bridge,input filter capacitor,power switch and output rectifier are reasonably selected.The snubber circuit is designed reasonably,and the high frequency interference of high frequency switching devices is absorbed,so the electromagnetic compatibility performance of the whole machine is improved.The design of the main transformer is the most important.This paper analyses and designs the transformer from the selection of the core material,the shape of the core and the design of the coil winding.The main transformer is designed optimally with low cost,low height,high efficiency,high reliability and high density.The welding machine designed in this paper adopts the PWM control mode of voltage mode,and the control IC is SG3525.The power switch can work safely and reliably at high frequencies by using transformer isolation driving mode in the driving circuit.The external characteristic required by SMAW welding machine is constant current external trailer characteristic.In this paper,the proportional-integral control circuit and the thrust current circuit are used to ensure that the welding machine has good workability.In order to ensure the safe and reliable operation of the welding machine,overheating and overcurrent protection circuits are designed.The control power supply circuit adopts a single-ended flyback topology with rated output power of 13 W.The transformer and buffer circuit of the control power supply are optimized.In the part of mechanical structure and heat dissipation design,a reasonable radiator is equipped for power switching devices and horizontal duct design is adopted.After structural optimization,the actual size of the prototype is 220 mm long,105 mm wide and 120 mm high.The rated output power of the prototype is 3.5 kW,the inverter frequency is up to 45 kHz,the weight is only 2 kg,and the power density is high.The no-load voltage and external characteristics of the prototype are tested and analyzed.Finally,electrical parameters and welding experiments are carried out on the prototype.The welding machine designed in this paper fully meets the requirements of electrical parameters and shielded metal arc welding technology.