Study On Soft-switching Circuit Of Half-bridge Arc Welding Inverter

The arc-welding inverter power supply has the advantages of well controllability, fast dynamic response and facility in realizing real-time control, which has great potential in performance. So it has been used more and more widely in the welding area. In the long term, arc-welding inverter power supply is the trend of welding power supply. But there are many problems in the tradition methods of hard-switching inverter arc-welding power supply, such as high switching losses, low efficiency and high electromagnetic interference (EMI) and radio frequency interference (RFI), which reduce its reliability and restrict the further development. Soft-switching is the main method to solve the problems above at present. However, the research in this area is keen on introducing the new circuit structure and control mode to achieve the soft-switching, which are difficult to be used in the hard-switching arc-welding inverter power supply having been put into used. The research in the following are made in order to apply soft-switching to the hard-switching arc-welding inverter power supply having been put into used.Firstly, the operating principle of consumable-electrode gas shielded arc-welding and the basic requirements for arc-welding inverter are introduced. The operation mode of a half-bridge arc-welding inverter already on the market has been analyzed, and then a small-signal model is built.Secondly, a soft-switching circuit which does not change the operation mode of half-bridge is proposed, of which operation principle is analyzed. When the circuit work correctly, the circuits of sixteen switching states are given, the theoretical waveforms of the main electrical variables are drawn, and the design principle of a few important parameters is also given.Thirdly, when the loading is invariable,the simulation study of this soft-switching circuit which does not change the work way of half-bridge is made, the simulation results verify the correctness of the theoretical analysis above. the simulation study of this soft-switching circuit which does not change the operation mode of half-bridge is also made when the loading is simulated as arc-welding, and simulation waveforms indicate that this soft-switching circuit can achieve zero-current turn-on and zero-voltage turn-off whether in short circuit state or in arcing state, while does not changing the operation mode of original circuit. Fourthly, experiment study of this soft-switching circuit which does not change the operation mode of half-bridge is made based on theoretical and simulation analysis above, and the design principle of main circuit, auxiliary circuit, control circuit and driving circuit is given. The experiment results verify the correctness of theoretical and simulation study above.