De-Coupled Control of Energy-Efficient High-Power CC/CV Power Source for Arc Welding

Abstract

In industry, for superior utilization of large capital equipment, a single large-current high-power converter is desired to convert electrical energy to a controlled high-intensity heat source to cater to the dynamic requirement of several welding methods (e.g., welding, hard-facing, gouging, weld overlay, etc.). The dynamic process behavior of multi-input minimally semiautomatic or single-input manual processes could follow either constant voltage (CV) or constant current (CC) arc type. Due to completely different type of arc or load characteristics, this article proposes a de-coupled control approach to guide the power source to independently take care of each arc type. It proposes feedforward control for CV arc type and robust second order sliding mode control (SOSMC) approach for dynamically uncertain CC arc type for manual welding. It further highlights that low-loss resonant or soft-switching topologies are less compatible for decoupled control of high-power loads with wide range impedance characteristics. For desired energy efficiency of a full-bridge DC-DC converter for arc welding, this article details that robustness features of SOSMC could be used for superior component engineering that incur low power loss. Finally, this article completely validates the proposed idea in a 1000A power converter for both CC and CV arc types.