Research On Three-Level Three-Phase Single-Stage Power Factor Correction Technology

The rectifying-type AC/DC power converter, whose input power factor is very low, is now becoming the most primary source of harmonic contamination. With the wide application of this type of convert, its harmfulness is more and more recognized. Since the issue and implementation of the standard of limitation on harmonic (such as IEC555-2) in 1990s, the technology of active power factor correction (PFC) has been paid more and more attention to and developed quickly.This paper introduces the basic principles and methods of the power factor correction technology first, analyzes and compares the present status of three-phase power factor correction technology. In compliance with developing trend and with the requirement of simplifying circuit structure and improving the efficiency of electric energy conversion, a single-stage isolated AC/DC converter with simple structure, high efficiency and high power factor is proposed ,which can achieves power factor correction, AC/DC power conversion and obtains lower output voltage directly meanwhile resolves the problems in electric isolation between AC side and DC side, voltage rating of power switches. Although increasing switching frequency is the effective way of decreasing the size and weight of power converter, the loss of device and distortion of harmonic should not be ignored with the increment of switching frequency. By using the technology of soft-switching, the loss of device can be reduced even eliminated, so soft-switching is inducted to the single-stage power factor correction converter to increase the switching frequency and the efficiency.This paper proposes a circuit which can achieve the PFC function must be working at discontinuous mode of inductance current. So it is a very important work to obtain the boundary mode condition of continuous conduction mode and discontinuous conduction mode in PFC circuit which is obtained by analyzing the principle of power factor correction and using some simplify condition. It is also can be called discontinuous mode of inductance current when the converter is used of power factor correction.To prove the correctness of theoretical analyses the PSPICE simulation software is used to simulate the circuit and the experiment circuit is designed. Both the result of the simulation and the experiment of the circuit indicate that the circuit achieves a better result of the power factor correction and realization of soft-switching which shows the good prospect of the application of this converter system.