Secondary Time-frequency Analysis for Arc Energy Characteristics of AC Square Wave Submerged Arc Welding

In process of AC square wave submerged arc welding, electric signal waveform determines the arc energy characteristics in the time and frequency domain, which also reflects the arc stability of welding process and quality indirectly. Using Wigner-Ville distribution (WVD), time frequency analysis is conducted to the current signal of AC square wave submerged arc welding. The Pseudo Wigner-Ville and smoothed Wigner-Ville distribution are discussed separately to suppress the cross-term interference. The numerical results indicate that the Choi-Williams kernel function has much superiority for time frequency analysis of the submerged arc welding electric signal. It can effectively suppress cross-term and eliminate noise in the Wigner-Ville distribution of welding electric signal, as well as owing the ability to portray the local feature of arc energy in AC square wave submerged arc welding.