Research On Single Phase Two Stage PFC Power Supply

With the rapid development of power electronic technology, the performance of switching power supply is rising, switching power supply with its excellent performance and relatively low price applied in agriculture, industry, national defense and other fields of daily life. Switching power supply in the use of the process will produce harmonics, and a large number of its use will produce serious harmonic pollution of the power system. In recent years, the harmonic pollution caused by power electronic equipment has been paid more and more attention.In order to improve the power quality, power factor correction (PFC)technology is usually used in power electronic equipment. The power factor correction technology mainly concentrated in the research of improving power density and efficiency of power equipment, Boundry conduction mode PFC (BCM)mainly be used in the small and medium power applications, can realize the diode current zero crossing off, and reduce the volume of the magnetic core inductor compared to the continuous conduction mode (CCM).This paper analyzes the development situation of power factor correction circuit and two switch forward circuits, aims to the characteristics of the two stage type power factor correction circuit, combining the power factor correction circuit and critical mode two switch forward converter. The first stage uses a constant turn-on time interleaved critical conduction mode power factor circuit to reduce the input current ripple and output capacitor ripple. In this paper,the principle of Boost mode power factor correction circuit is presented,and the parameter design of the circuit is given. The UCC28063 and TL494 are used to make the two switch forward converter with PFC pre modulation.The switching frequency and the peak current of the PFC inductor are different in different time periods. In this paper, the power loss of the PFC inductor is obtained by using the method of subsection integration. According to the change of PFC switching frequency,the small signal modeling is difficult. In this paper,the principle of charge conservation is used to simplify the modeling process.