Reserch Of Single-Stage Single-Switch Flyback PFC Converter

According to the rectifier circuit is composed of diodes and filter capacitor, it is used in the front-end power as electric equipments widespread. But this kind of circuit exists in the nonlinear, so the input current isn't sinusoidal. It contains many harmonic components and at the same time the factor is lower. The Power Factor Correction AC-DC converter is a power inverter circuit, it has the function of realizing factor correction, isolating output voltage isolated, stabilizing, maximizing the absorbed active power. Due to there are no harmonic components, the mutual interferences between PFC circuit and the other apparatus of using the same power supply will be reduced. Now the Europe electric appliance must be coincident with the Europe criterion EN61000-3-2 that is applicable for 75 W or upward input receiving power of most electrical appliance.In small and medium situation, the demand of the single stage power factor correction converter becomes more and more urgent. Because such converter has some merits of simple circuit topology, easy control, small volume, low cost and so on. In this paper a new single stage power factor correction converter has been introduced and researched profoundly.First and foremost, the paper raises a single stage, single switch and high efficiency PFC converter topology. It combines with PFC circuit and the Flyback converter which owes center tap transformer. The forestage PFC circuit has three operational modes: non-conduction mode, flyback operational mode, Boost operational mode. The backstage DC to DC circuit operates in the flyback mode. When the forestage circuit operates in the Boost operational mode, it can supply energy for the backstage supply capacitor. The energy from the Boost operational mode transfers directly through forestage flyback can improve efficiency of converter. Secondly, making use of the passive and no-destructive clamping circuit can increase the conductive angle, absorb the leakage energy and reuse, improve the efficiency of converter and at the same time the clamper can limit the drain-source voltage of switch. This paper analyzes detailedly the operational principle and steady-state characteristic, then designs the capacitor parameter, tests the practicability through simulation and experiment.In the end, according to the theoretical research of the PFC circuit topology. Two 90 W/19 V prototypes have been made for experiment. The key circuit waves have been measured and the measured results are the same with theory. The experiment verifies the correct theory analysis. At last this paper analyses the shortages of the PFC circuit and makes further analysis according to the necessary improvement.