Research On Interleaved Two Transistor Forward Converter

High power density as well as high reliability has always been the goal to pursue in the field of moden electric power converters, Power Factor Correction(PFC) and two transistor forward provide an effective way. So, this paper presents a interleaved two transistor forward with PFC ahead.This paper introduces the bad effect of harmonic, then put forward several restraining method and illustrate the principle of PFC, finally presents the designing processing of the main circuits and the control system with the average current mode control using chip UC3854BN.This paper compares the few basic DC/DC converter, illustrating four kinds of PWM feedback control method, analyzing the principle of interleaved two transistor forward and the performance of its transformer, comparing the average current control and the peak current control, emphasizing the advantages and the disadvantages of the peak current. Furthermore, it introduce the chip UC2846 which uses peak current control method, deduce the signal model of the Buck circuit using peak current mode control with slope compensation in detail, then make frequency domain simulation to the model, at last carry out the design process of the system.The experimental results indicate that the interleaved two transistor forward with PFC ahead can not only make the input current follow the input voltage, reduce the distortion of the input current, restrain the pollution to the power system, but also can increase the output equivalent frequency, reduce the output ripple. The circuit is stable and highly reliable, thus, it is usable.