Fast frequency-variable polarity TIG welding power source and system based on SiC module

Abstract

The invention provides a fast frequency variable polarity TIG welding power source and system based on a SiC module. The welding power source comprises a double-path parallel power main circuit, a control circuit and a man-machine interaction system. The double-path parallel power main circuit comprises a three-phase rectification filter circuit, a fast frequency pulse current main circuit and a variable polarity current main circuit; each of the fast frequency pulse current main circuit and the variable polarity current main circuit comprises a primary inverter circuit, a high-frequency transformer and an ultrafast recovery rectification smoothing circuit which are connected in sequence; the fast-frequency pulse current main circuit further comprises a filter inductor and a high-frequency switching circuit which are sequentially connected behind the ultra-fast recovery rectifying and smoothing circuit. The variable polarity current main circuit further comprises a coupling inductor and a secondary inverse current conversion circuit which are sequentially connected behind the ultrafast recovery rectification smoothing circuit. The welding power source can reduce the size, is high in dynamic response speed, low in switching loss, high in energy efficiency and stable and distortionless in output waveform, and can improve the welding quality.

Description

technical field [0001] The invention relates to the technical field of welding equipment, and more particularly, to a fast-frequency variable-polarity TIG welding power source and system based on a SiC module. Background technique [0002] The variable polarity welding power source plays an important role in the welding process of magnesium and aluminum alloys. Due to the high thermal conductivity and high thermal expansion coefficient of magnesium alloy, aluminum alloy and other alloys, and the surface layer is prone to oxidation to form an oxide film, DCEN (direct current connection) or DCEP (direct current reverse connection) DC tungsten inert gas shielded welding (Tungsten Inert Gas , TIG) are prone to defects such as coarse grains, slag inclusions, tungsten electrode burning, and thermal cracks. The variable polarity tungsten inert gas welding (Variable Polarity TIG, VPTIG) process has the function of cathode cleaning, which can break and clean the oxide film on the me...

AI Technical Summary

Problems solved by technology

At present, the VPTIG welding power sources on the market still have problems such as low control accuracy, slow response speed, irregular output current waveform, excessive heat input, slow zero-crossing speed of polarity change, and easy arc breakage. For example, the Chinese invention patent " Welding power supply and AC-DC argon arc welding machine" (public number: CN105817740A) and "short-circuit type AC welding control circuit and welding power supply" (public number: CN111001901A) still use Si-based IGBT modules as switching power tubes in the inverter main circuit, Its inverter frequency usually cannot exceed 20kHz, so its response speed and control accuracy are difficult to be greatly improved

[0003] On the other hand, since the performance parameters of Si-based power devices are close to the theoretical limit determined by their material characteristics and manufacturing process, it is also very difficult to rely on Si-based power devices to improve the overall performance of welding power sources.

Si IGBT has a tailing effect and a long tailing off time, which will cause a large switching loss, and it is difficult to further improve the commutation efficiency and commutation speed of the welding power source

Although Si MOSFET has slightly improved turn-off delay time and turn-off loss, its withstand voltage and current flow capacity are generally low, and it is not suitable for high-power applications

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