Race-Control Algorithm for the Full-Bridge PRCP Converter Using Cost-Effective FPGAs

In this paper, the unedited race-control algorithm (RCA) for the full-bridge passive resonant commutated poles (FB-PRCP) converter is presented and implemented with a field-programmable gate-array technique. It compensates the drawbacks of that topology that are related to the slow dynamics of the auxiliary poles which are necessary to obtain zero-voltage transitions both at turn-on and turn-off conditions and makes possible its use in more general welding applications, such as manual metal arc welding, in which very fast responses are required. The proposed RCA is a simple variation of the traditional phase-shift technique, which leads to significant efficiency improvements. The guiding idea is to apply the phase-shift technique to both legs of the converter, contrarily to what has been done to date. Leg B is delayed when phase shift must be increased, whereas leg A is delayed when a phase-shift reduction is needed, contrarily to the traditional phase-shift technique, where Leg B is delayed or anticipated and Leg A is held at a fixed phase. In this way, the limitation in dynamics of the converter is completely eliminated and it gains much more readiness. The effectiveness of the RCA has been experimentally tested on a true converter.