Adaptive variable polarity plasma arc welding power supply

Abstract

The invention discloses a variable polarity plasma arc welding power supply which can adapt to different voltage requirements of a direct current straight polarity arc and a direct current reverse polarity arc, and belongs to the field of material processing. Three-phase alternating current is input to a dual-output direct-current constant current power supply part; an output end of the dual-output direct-current constant current power supply part passes through a current transformer used for acquiring a current signal; an output end, subjected to sampling, of the current transformer is connected to a control unit; the control unit outputs a control signal to the dual-output direct-current constant current power supply part; an output end of the dual-output direct-current constant current power supply part is connected to a secondary inversion unit through coupling inductance; output of voltage, current and a temperature acquisition circuit in the secondary inversion unit is connected to the control unit, the control unit outputs a control signal, and the control signal is modulated through a secondary drive circuit to be conveyed to the secondary inversion unit. The variable polarity plasma arc welding power supply can be in operation in various modes, adapts to the different voltage requirements of the direct current straight polarity arc and the direct current reverse polarity arc, and meets the different welding process requirements.

Description

technical field [0001] The invention relates to a polarity-changing plasma arc welding power supply capable of adapting to different voltage requirements of DC positive connection (DCEN) and DC reverse connection (DCEP) arcs, belonging to the field of material processing. Background technique [0002] Variable polarity plasma arc welding (VPPAW) is asymmetric square wave AC plasma arc welding, which is a new type of high-efficiency welding process developed for aluminum and its alloys. It combines the advantages of variable polarity TIG welding and plasma welding. The characteristic parameters can be flexibly and independently adjusted according to the process requirements. One side of the plate is welded at one time and two sides are freely formed; due to the small welding deformation and high productivity, compared with other high-energy beam welding processes (electron beam welding and laser welding), the equipment is simple, the cost is low, and there are few defects suc...

AI Technical Summary

Problems solved by technology

For example, when the polarity-changing plasma welding power source is used for polarity-changing (AC) welding, the welding process requires a lower voltage when working with DC positive connection (DCEN), and the welding process requires higher voltage when working with DC reverse connection (DCEP). , if the traditional single power supply method is used, when the secondary inverter of the power supply switches between DC reverse connection (DCEP) and DC positive connection (DCEN) states, the duty cycle of the trigger pulse of the front-end power supply needs to be greatly adjusted , which requires the pre-stage power supply to have a large voltage adjustment rate. However, generally in the design of the power supply, the working voltage requirements for DC positive connection (DCEN) and DC reverse connection (DCEP) are often not compatible. If DC positive connection ( The required voltage design when working in DCEN), the power supply voltage will be too small to meet the requirements when working in DC reverse connection (DCEP), if the required voltage design is in accordance with DC reverse connection (DCEP), work in DC positive connection (DCEN) At this time, the trigger pulse of the pre-stage power supply will be very narrow, which may lead to unstable performance of the power supply

[0004] To solve the above problems, the most traditional method is to use two DC constant current power supplies with different performances as the power supply for DC positive connection (DCEN) and DC reverse connection (DCEP). The circuit diagram is as follows: figure 1 As shown, although this design can solve the above problems, the front stage needs two DC constant current power supplies with different performances, and the secondary inverter uses a full-bridge inverter circuit, which is costly

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