Research On Single-phsae High-power PFC Techniques For Airborne System

Power Factor Correction(PFC) technology can improve the power factor and reduce the pollution to the power grid of the non-sinusoidal current harmonics in the rectifier circuit effectively and significantly reduce the harmonic distortion. The Boost Active PFC technology has become the mainstream of PFC technology because of its general advantages. However, in the input condition of airborne system(115V/400Hz), the input current would distort at the zero-crossing of the input voltage and the current harmonics increase so it is difficult to satisfy the limits specified in RTCA DO-160 D,which becomes a barrier to the development of PFC technology in airborne system. The purpose of this thesis is to reduce the zero-crossing distortion at high input frequency application.The research of this paper is based on the average current control of single phase PFC Boost converter in CCM mode. Firstly this paper models the Boost PFC converter and presents the mathematical model of the power transfer function and the control circuit of the converter, derive the input admittance function, thereby analyze the generation process of zero-crossing distortion and points out that the major three causes are the phase displacement between the input current and input voltage 、 the time of the converter working in DCM process and the inductor. In view of these three causes, this paper puts forward the detailed solution which are improving current loop crossover frequency(correspondingly increasing switching frequency) and reducing inductance. Finally the methods are verified by simulation.This paper adopts the two-phase interleaved technology as the Boost PFC topologies to improve the zero-crossing distortion. The advantages of interleaved converter to traditional single-phase converter in reducing inductance and increasing the equivalent switching frequency and its effect to solving the zero-crossing distortion phenomenon areanalyzed.Finally extended it to N-phase interleaved converters, which provides a new method to solving the worse zero-crossing distortion for the high input frequency(360~800Hz) PFC application in airborne system.A 1000 W two-phase interleaved Boost PFC converter is designed with UCC28070 as the control chip, the design process of the main circuit and control circuit is described in detail.Besides the surge current suppression circuit is added then it’s compared with another traditional PFC prototype.The experimental results show that the interleaved Boost PFC converter can effectivly improve zero-crossing distortion and has lower input current harmonics than the traditional Boost PFC converter and it can satisfy the limits specified in RTCA DO-160 D. Besides the work effect of the surge current suppression circuit is obvious and the maximum value of the surge current is suppressed to the 1/4 of the original.