Mechanism of magnetic bias exists in power transformer of the single-stage full bridge PFC converter

A single-stage full bridge soft-switching power factor correction circuit that adopts phase-shifted control mode is designed, which can realize functions such as power factor correction, soft-switching, output voltage regulation and electrical isolation. However, besides those existing in common full bridge converters, there are new factors because of the special control model and the required power factor correction function. Which lead to magnetic bias occur in the main circuit. Through analysis of the topology of the converter and the mechanism of the magnetic bias, various factors that affect the magnitude of the magnetic bias are pointed out. A solution is then given to restrain the bias effectively and the computer simulation and experimental results prove the validity of the theoretical analysis.