Design, analysis, fabrication and practical testing of a lab developed power converter prototype in electric arc welding

This paper presents design, parameter evaluation, fabrication and testing of an input power factor corrected phase modulated resonant transition converter(PMRTC) for electric arc welding. A power factor correcting boost (PFC-boost) converter is connected at the front end of PMRTC to improve its input power factor closer to unity. PMRTC is a full bridge isolated DC-DC resonant converter whose output voltage is controlled by using phase shift PWM technique. The switching devices of the PMRTC are turned-ON with zero voltage across it. This minimizes total switching loss and improves efficiency. The switching frequency of the PMRTC is kept high (μ 50kHz) so that the size of the isolation transformer is reduced. Both the converters are designed, analysed, fabricated and tested separately and thereafter connected in cascade. Practical welding operation at 2.5 kW, 100 A is carried out with the cascaded converter and the experimental results are presented. The effect of sudden loading on output voltage of PFC-boost is also practically observed. The experimentally obtained results are found to be in excellent agreement with the simulated results. This upholds the accuracy of the work.