Single-stage full-bridge PFC technique based on clamp circuit

Because of the leak inductance of transformer, the power switch on-off operation of single-stage full-bridge PFC (Power Factor Corrector) generates high over - voltage, which increases the voltage stress of power switch and lowers the stability of corrector. The PFC based on clamp technique is presented, which realizes the power factor correction and DC/DC conversion with single stage structure. The over-voltage is absorbed by the clamp circuit and the voltage stress is lowered. Its working principle is explained. Based on the structure of PFC, the mechanism of magnetic bias generation in the high frequency transformer is analyzed and the countermeasures are presented. Experimental results show that, the proposed PFC achieves higher power factor and DC/DC conversion efficiency, which verifies the validity of the theoretical analysis.