Research On Digital Control Strategy Of Arc Welding Inverter Power Supply Based On DSP

As a core part of welder, arc welding power source provides power for the weldingarc, that’s why it’s the key to the development of welding technology. In recent years, thearc welding inverter control system based on DSP as the core control has attracted wideattention of researchers due to its high flexibility.This paper makes an overall design for4.2kVA half-bridge inverter arc weldingcontrol system. It uses a control structure combining DSP and FPGA to realize the closedloop feedback control of arc welding inverter. This design is mainly to do the controldesign section with DSP as the core part. The research on arc welding inverter can bemainly divided into main circuit and control circuit parts. For the main circuit design, thefocus is to calculate basic parameters of every part in AC-DC-AC-DC conversion,including the selection of rectifier bridge, IGBT selection and design of transformer. Onthe basis of calculating the main circuit parameters, this paper uses state space averagemethod to set up small signal switch model of main circuit. According to the outputcharacteristic requirements of the arc welding inverter power source, the parameters ofthe inverter output filter and its PI controller are designed. In addition, the use ofMATLAB simulation is to compare bode plots before and after the compensation. It’sobvious that the system’s stability has been improved. For the control circuit design,firstly, internal resources of TMS320LF2407DSP are introduced briefly. Then, it designssignal sampling circuit and conditioning circuit. For the software design, this papermainly uses DSP chip programming to complete A/D conversion of welding current,digital filter, PI control algorithm and other functions. It also outputs the PI output valueto FPGA through the digital input/output ports.Finally, the machine test is completed in the arc welding inverter experimentalplatform, whose power supply is about4.2kVA. The experimental results and simulationresults are basically consistent. The correctness of the theoretical analysis has beenverified.