Input-series common transformer connected PS-FB DC-DC converters for pulsed MIG welding

A pulsed Metal Inert Gas (PMIG) welding system is built based on the input-series common transformer connected phase-shifted full-bridge (PS-FB) DC/DC converters. Because the input-series connected converters share the same transformer magnetic core, equal sharing of input voltage can be achieved automatically without special voltage sharing control. To enhance the reliability of the system, a hybrid peak current control strategy consisting of arc length loop, average current loop and peak current loop is adopted. The system stability is analyzed based on the small signal model. The effectiveness of the proposed topology and its control strategy are verified by experimental results of a 15kW-50kHz welding machine.