PFC voltage-regulating resonant MIG welding power supply system and control method

Abstract

The invention discloses a PFC voltage-regulating resonant MIG welding power supply system and a control method. The system comprises a single-phase alternating current input power grid, a PFC circuit, a current sampling circuit, a digital control circuit, an analog control circuit, an LLC resonant converter and an arc load. The digital control circuit interacts with the PFC circuit through the resistance adjusting circuit so as to control the feedback resistor and the LLC resonant converter to work at the optimal resonance point all the time, and high working efficiency is obtained. According to the main control strategy, the welding current is detected and processed through the digital control circuit, and then feedback resistance of the front-stage PFC circuit is adjusted, so that the output voltage of the front-stage PFC circuit is adjusted, then the output voltage of the rear-stage LLC resonant converter is adjusted, it is guaranteed that when the arc load changes, the welding current is kept constant, and therefore the welding quality of MIG welding is improved.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a PFC voltage-regulated resonant MIG welding power supply system and a control method. Background technique [0002] Welding technology is an important part of manufacturing technology and is widely used in the manufacturing process of railways, aerospace, ships, mining machinery and automobile industries. Among them, MIG welding is one of the most efficient welding techniques. However, among the existing MIG welding power sources, the most widely used topology of the main circuit of the power source is the traditional hard switching or phase-shifting full bridge. In traditional hard switching, the power switching device will be in the state of being forced to turn off (non-zero current) and forced to turn on (non-zero voltage), which will bring serious switching loss, and the loss will become more serious with the increase of frequency, resulting in high efficiency. Low, and ...

AI Technical Summary

Problems solved by technology

However, the change of output voltage will cause the LLC resonant converter to deviate from the optimal resonance point, resulting in a decrease in efficiency

Therefore, the application of LLC resonant converter in welding field is limited

[0004] There are a large number of high-order harmonics at the input end of the single-stage LLC resonant converter, and the problem of polluting the power grid still exists

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