The Research Of Single-Phase Two-Stage Power Factor Correction

With the high efficiency, low power consumption, light weight, and the wide voltage range, the switching power supply dominates the field of power. However, because of its nonlinear characteristics, the switching power supply resulting input current contains a large number of odd harmonics, which cause serious harmonic pollution for the grid. Active power factor correction (APFC) technology is the most effective way.Firstly, this paper described the research condition and the hotspot of APFC technology, analyzed and compared the passive PFC, single-stage PFC and two-stage PFC techology. Towards to the bulk DC-link capacitor is one of the largest components in two-stage PFC convert, this article take the Leading/Trailing Edge Modulation (LEM/TEM) method, which is employing Leading Edge Modulation for the first PFC stage and Trailing Edge Modulation for the second DC/DC converter stage can significantly reduce the ripple current and ripple voltage of the DC-link capacitor. Thus, a smaller DC-link capacitance can be used. Detailed mathematical analyses are given to the calculation of the DC-link capacitor ripple current reduction with LEM/TEM strategies and TEM/TEM respectively. By deduction, confirmed LEM/TEM capacitor ripple current is less than the TEM/TEM, and the simulation is verified the theory properly.Two-stage PFC converter belongs to cascaded system, usually each module is independent designed based on its own stand-alone operation, and there could be potential interaction in such systems when the modules are integrated together. In this paper by using average modeling method to small signal analysis, the model of PFC converter and DC/DC converter are obtained, then, base on the Impedance Ratio Criterion, the stability of the two-stage PFC converter is detailed analyzed.Finally, Boost PFC in first-stage and Double Forward DC/DC converter in second-stage are used in designing a 240W two-stage PFC circuit, given the main circuit and close loop parameters of the calculation, experimental results prove the validity of design.