Analysis of Flux Density Bias and Digital Suppression Strategy for Single-Stage Power Factor Corrector Converter

Single-stage power factor corrector (PFC) ac/dc converter with galvanic isolation is preferable in some industrial applications due to its characteristic of cost-effective and high-power density. However, the transformer used for isolation in such topologies can be easily saturated. In this paper, the generation principle of flux density bias for the transformer involved in the single-stage (SS)-type full-bridge (FB) power factor corrector (PFC) converter is analyzed in detail. The maximum flux density bias during every line period is obtained by recursion. Conventional suppressing strategies of flux density bias are analyzed, and a digital suppressing approach is proposed. A 5 kW SS-FB PFC prototype is built and tested, and the proposed control strategy is implemented by means of a digital signal processor (DSP) board based on the TMS320LF2407A. The feasibility of the proposed approach is well verified through the experimental results.