Study On DCM Boost PFC Converter Modeling And Analysis Considering Parasitic Parameters

The parasitic parameters of a boost power factor correction(PFC)converter lead to input current distortion when the converter operates in discontinuous conduction mode(DCM),and using an RCD snubber is a simple and effective way to suppress the parasitic oscillation.In this dissertation,the influence of RCD snubber circuit on DCM boost PFC converter and the selection principle of RCD optimal parameters are studied.Firstly,the background of PFC technology,the working mode and the control strategy of boost PFC converter are introduced.And the research status of parasitic parameter oscillation in DCM boost PFC converter are presented.The working principle of DCM boost PFC converter and the main parasitic parameters of each component in the circuit are given.Secondly,the boost PFC converter with RCD snubber circuit is theoretically analyzed,and the equivalent circuit of each oscillation stage is established.According to the root locus of the differential equation of inductance current,the distribution of the characteristic root is revealed,the distribution diagram of the characteristic root under different RC parameters is obtained,and the expression of inductance current in several cases is deduced in detail.The influence of RC parameters in different characteristic root forms on the parasitic oscillation is analyzed.Then,according to the inductance current average model,the relationship between the RC parameters and the total harmonic distortion rate of the input current is established,and the expression of the optimal parameters and the parasitic parameters is obtained.According to the different rated load power,the converter parameters are designed and the power devices are selected according to the common mainstream device manufacturers.The proposed method is used to calculate and select the RC parameters,and the generality of the proposed principle is verified.Finally,a prototype of a boost PFC converter with rated power of 1kw is built and tested under different input voltages and loads.The experimental results show that the RCD absorption circuit can suppress parasitic oscillation better,and the experimental results are consistent with the theoretical analysis.