Simulation And Experimental Study Of The Inverter Dc Arc Welding Power Supply

Inverter arc welding power supply develops accompanying with the reliability, stability,efficiency and electromagnetic compatibility problems and so on.Performance optimization of arc welding power supply is an eternal topic.Therefore,a systematic modeling,simulation and experimental study on the inverter arc welding power supply have been accomplished focuses on the above problems.The contents of the paper is listed as follows:(1) This paper systematically introduces the principle of main circuit,control circuit, arc properties and requirements for arc welding power supply.Then using Matlab/Simulink and SimPowerSystems,the simulation model based both on devices and mathematics has been established for main circuit,control circuit and arc load.Based on these models, systematic and comprehensive simulation study for the entire system can be conducted.(2) Simulation and experimental study on dynamic characteristics of inverter arc welding power supply has been completed.The output inductor is closely related to the dynamic characteristics of inverter arc welding power supply,so firstly the frequency-domain analysis based on transfer functions theory has been done.Effects of inductor on dynamic characteristics have been analized.And simulation results show that the selected inductor parameter is reasonable.At the same time,other circuit parameters have been determined according to simulation results.Finally,experiments test have been carried out under the conditions of open load,welding practices,open load to short circuit, load to short circuit and short circuit to load,and experimental waveforms have been obtained.Experiment results show that the system has good weld ability and favorable dynamic characteristics which meet the need of welding technology.Moreover,the experimental waveforms are consistent well with the simulation results,which further verify the exactness of the parameters obtained from simulation and theory.So the model we established and the research method we used prove reasonable.(3) Improvements for main circuit of inverter welding power supply has been proposed and verified through experiments.The conventional half-bridge circuit in inverter welding power supply contains two large electrolytic capacitors and soft-start circuit for restraining inrush current,so the circuit is much bulky.It's known that the electrolytic capacitor is not suitable for high frequency converter,so it prohibits the inverter welding power supply from high-frequency applications.For this reason,we have improved the main circuit.The proposed main circuit remarkably reduces the capacitance of capacitors,adopts input EMI filter,removes soft-start circuit,thus the volume and the cost of the system is further reduced.Comparative analysis and experiments have been carried out,and the research results show that the proposed circuit has many other improvements in increasing the power factor and efficiency,restraining inrush current and the harmonic distortion.(4) Preliminary simulation study on nonlinear phenomena in inverter welding power supply has been done.Firstly,the equivalent Buck circuit topology of half-bridge circuit has been derived,which very cleverly simplifies the modeling of half-bridge circuit.So the existing study method can be used in this research.Simulation results show that at the operating point 24V/100A,when value of input voltage,filter inductor and equivalent welding capacitor varied,simulations have been done and the change of system dynamic behaviors is obtained and prove the existence of chaotic phenomena.After analyzing the simulation results,the following conclusion can be drown:the wide fluctuation of input voltage,the improper transformer ratio,and the large variation of welding equivalent capacitor and unfit filter inductor parameters can bring the converter into chaotic operation extent.The research conclusions have important directive to the selection of circuit parameters.The research in this paper affords benefit for increasing the reliability of the inverter arc welding power supply.This study conforms to the development trend of "high frequency and green welding machine",and provides the potential for the further improvement of the dynamic performance of welding machine.