Comparison Research of Digital and Analog Control For Single-Stage Power Factor Correction AC/DC Converter

Single-stage power factor correction converter is preferable in some industrial application due to its characteristic of cost-effective and high power density. Generating principle of flux density bias for transformer involved in single-stage(SS) type full-bridge(FB) PFC converter is detailed analyzed, maximum flux density bias during every line period of input voltage is obtained by recursion. Mathematic model of ferrite loss increment for core resulted by flux density bias is quantitively built and analyzed, moreover the demonstration model is obtained by MATLAB. Suppressing effect of flux density bias(magnetizing density bias) by adopting fully digital control strategy is analyzed, further two digital suppression strategies are presented, and the feasibility and validity of preferable strategy is verified by experimental results. Finally, a prototype, whose maximum output power is about 300 W and PFC frequency is 55 kHz, is built to verify the validation of presented preferable suppression strategy, experimental result of conventional analog control implementation is also given for comparison. Further, conversion efficiency is greatly increased and operating performance is excellent, PF value and efficiency of full load are respectively 0.99 and more than 92%. In addition, conversion efficiency curves of different operating frequency are given for comparison by experiment.