SiC IGBT Variable-Polarity Welding Power Source for Stable Arc Re-Ignition
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Solution Overview
Problem
Existing variable-polarity welding power sources face challenges in maintaining arc stability during polarity changes, particularly due to excessive high-voltage pulse voltages that can damage IGBTs and result in inefficient arc re-ignition.
Innovation Solution
A digital variable-polarity welding power source based on SiC IGBTs, featuring a main circuit with a three-phase rectifying and filtering circuit, SiC IGBT primary and secondary inverter circuits, and a high-voltage arc stabilization circuit, along with a control circuit that includes a controller, power supply control module, and drive modules for precise control and arc stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-bridge structure circuit topology stabilization strategy is used to provide high-voltage pulse to the arc at the moment of current commutation, then arc re-ignition is achieved, but IGBT breakdown and damage occurs in high current welding
Solution Approach 1:
The patent changes the voltage parameter of the arc stabilization circuit by using a voltage transformation circuit to step down the high-voltage pulse from the original full-bridge structure to a lower, safer voltage level that prevents IGBT breakdown while still enabling reliable arc re-ignition during polarity switching
2Reliability
If full-bridge structure circuit topology is used for arc stabilization, then arc re-ignition is achieved, but system complexity and cost increase
Solution Approach 1:
The patent extracts and removes the complex full-bridge structure from the system, replacing it with a simplified voltage transformation circuit that retains the essential arc stabilization function while eliminating unnecessary complexity and reducing system cost
3Device complexity
If half-bridge structure circuit topology stabilization strategy is used, then system complexity is reduced, but arc stability deteriorates due to slow current direction switching
Solution Approach 1:
The patent changes the voltage parameter through a voltage transformation circuit that actively controls the voltage applied to the arc during polarity switching, enabling fast current direction switching and maintaining arc stability without requiring the complex full-bridge structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high conversion efficiency of up to 93%, reduces system complexity and cost, ensures reliable and stable arc re-ignition, and produces high-quality welds with minimal spatter, while being energy-efficient and environmentally friendly.
Implementation Method 1
a three-phase rectifying and filtering circuit, a SiC IGBT primary inverter circuit
Implementation Method 2
three-phase rectifying and filtering circuit
Implementation Method 3
SiC IGBT primary inverter circuit is used to modulate the DC into a high-voltage, low-current high-frequency AC square wave
Implementation Method 4
a high-frequency transformer is used to isolate the circuits before and after the transformer and modulate a low-voltage, high-current high-frequency AC square wave
Implementation Method 5
a SiC ultra-high-frequency rectifying and filtering output circuit
Implementation Method 6
SiC ultra-high-frequency rectifying and filtering output circuit is used to rectify and filter high-frequency AC square waves into DC
Implementation Method 7
a SiC IGBT secondary inverter circuit is used to convert the polarity of the DC output by the SiC ultra-high-frequency rectifying and filtering output circuit to form a variable-polarity current required for welding
Implementation Method 8
a high-voltage arc stabilization circuit is used to provide a reverse high voltage for the arc space when the welding current changes polarity to ensure reliable re-ignition after the arc is extinguished at the instant of the current zero crossing
Data Source
AI summary
A digitized variable-polarity welding power source based on SiC IGBT, comprising a main circuit and a control circuit. The main circuit comprises a three-phase rectifying filter circuit, a SiC IGBT primary inverter circuit, a high-frequency transformer, a SiC ultrahigh-frequency rectifying filter output circuit, a SiC IGBT secondary inverter circuit and a high-voltage arc stabilizing circuit which are sequentially connected. The control circuit comprises a controller and a power supply control module, and a digitizing tablet, a SiC primary inverter driving module and a SiC secondary inverter driving module which are in connection with the controller via signals.