Research Of SMAW Inverter Power Supply Based On WBG Semiconductor Power Device

Research of inverter welding power sources in our country started in the early 1980 s,forming three generations, the first generation is the inverter for arc welding using the thyristor tube as switching devices, which is noisy; the second generation is the inverter for arc welding using GTR or MOSFET as switching device, GTR poor thermal stability, the MOSFET current capacity. The third generation is the high inverter for arc welding using IGBT as switching devices with higher power, while the inverter frequency is lower than GTR, MOSFET. With the Si semiconductor power switch device performance approaches the theoretical limits, further development of inverter welding power supply is limited.Therefore, it is necessary to find a new frequency higher capacity greater switching devices to replace the traditional Si semiconductor switching device in inverter welding power supply. In this paper, we studied a kind of shielded metal arc welding(hereinafter referred to as the SMAW) inverter power source based on WBG semiconductor power devices with50 KHz switching frequency, which has smaller volume, lighter, and is energy saving,material saving, etc. compared with the traditional SMAW inverter power supply, and its control performance is superior, dynamic response more quickly, to real-time control of welding process.Pass characteristics, shutdown characteristics and the thermal characteristics of Si C MOSFET and Si IGBT were studied, and conduction resistance of SiC MOSFET is lower when the voltage of the device is low. What's more, SiC MOSFETs turn off faster and have better heat resistance when SiC MOSFETs and Si IGBTs are of same specifications. Full bridge inverter topology is designed according to the overall design objectives and programs.Main transformer, input rectifier filter circuit, an output rectifying circuit of the power conversion circuit were designed and calculated. SCH2080 KE of Rohm was chosen as the inverter switch and protection circuit for power semiconductor devices was designed.Inversion process of power converter circuit was analysed to prove its rationality. Constant current with the drag of external characteristic control circuit is designed according to the SMAW external characteristic requirement ncluding the current given circuit, current sampling circuit, thrust current circuit, proportional integral circuit and protection circuit of thermal flow. Driving circuit based on IR2110 with suitable driving power chip and driving chip is designed according to the driving voltage and current of SCH2080 KE.Inverter power supply designed was assembled and debugged, PWM output driver waveform of the UC3846 and driving waveform of the IR2110 were tested and analysed. In addition, external characteristic of the inverter power supply designed was collected. The tests proved that the driving waveform meets the design requirements, and the power switch device works normally, and the external characteristic control circuit meets the design requirements.