Open-circuit fault diagnosis of rectifiers fed GMAW process under different transfer modes

This study proposed a GMAW process modeling with a topology that includes two two-level rectifiers connected in parallel to operate under different transfer modes such as short circuit, mixed, spherical, and spray. The tests of the arc stability studied and compared to the experimental GMAW process of the PipeWorx 400 in order to know the effectiveness of the proposed model. The welding current and voltage, droplet diameter, and length of the weld wire can be easily extracted from the proposed model. This paper examined the dynamic behavior of the GMAW process under the healthy and faulty switch of the rectifiers, and proposed a new diagnostic technique based on the variations of the Boolean Mean Value (BMV) of the six currents of rectifiers. To estimate the droplet detachment frequency DDF, the technique of Single-Sided Amplitude Spectrum (SSAS) is applied to the welding current of the simulation model and experimental process. The obtained results showed a high similarity in performance between the proposed simulation model and the experimental process. The SSAS technique is capable of estimating the accurate DDF value in both healthy and faulty cases of the IGBT switch. The proposed BMV diagnostic technique proved the exact location of the open circuit switch of the rectifiers in a very short time up to 7 ms.