Research On ISOP-FB High Frequency Welding Power Supply

With the continuous maturity of the existing welding process,modern industrial production has put forward higher requirements for the welding process,and it has also brought greater challenge to the design of welding power supply at the same time.The welding power supply is developing in the direction of high frequency,light weight and digitalization.How to reduce the IGBT loss of the welding power supply,reduce the temperature rise of the IGBT,and ensure the efficiency and reliability of the power supply under the development trend of high frequency,has become the research focus of the welding power supply.IGBT is the core component of high-frequency welding power supply,and its power loss is an important part of the welding power loss.The over-temperature failure caused by the excessive loss of IGBT and power diodes is the most common and susceptible form of failure.The junction temperature problem caused by IGBT power loss directly determines the reliability of the switching tube,which affects the reliability of the welding power supply.The accurate calculation and measurement of IGBT loss is one of the difficulties in the design of switching power supply.Based on the highly equivalent IGBT model,more accurate loss simulation data can be obtained through professional electrothermal simulation tools.In addition,the temperature rise experiment is a common way to indirectly measure IGBT loss.Through the IPOSIM simulation tool,IGBTs with different capacities and IGBTs with different input voltage and current are subjected to simulation and temperature rise experiment to obtain the relationship between IGBT capacity and loss,and the relationship between voltage,current and IGBT loss.And the positive correlation is analyzed between stray inductance and IGBT loss.It provides a reference basis for the selection of welding power supply IGBT.In order to expand the output power of the welding power supply,the ISOP and IPOP topologies are used.The IGBT loss comparison results of the two topologies are obtained by performing loss simulation and temperature rise experiments on the two topological circuits,and a lower loss topology is selected as the welding power supply to expand the power according to the loss result.The control objects of the two control methods are compared and analyzed from the perspective of the mathematical model through mathematical modeling of the welding power supply in voltage mode and current mode,and found that the current mode control has the inherent characteristics of one less low-frequency poles,so its dynamic performance is better.A closed-loop model is built by MATLAB/SIMULINK software and PI parameters are designed suitable.An ISOP prototype is built based on current mode control to verify the dynamic performance advantages of current mode control.