平均电流型Boost PFC变换器中过零畸变

有源功率因数校正变换器中,通常会使用滤波电容来吸收开关纹波和噪声。在中频(360～800Hz)应用场合,流入滤波电容的电流会变得很大。滤波电容的电流超前输入电压90°,这样功率因数就会变得很差。同时电流环在中频情况下会产生超前相位。电流环和直流滤波电容造成的超前相位致使输入电流在输入电压过零附近产生严重的畸变。通过分析输入滤波电容和电流环的影响,指出直流滤波电容是引起输入电流发生过零畸变的重要原因之一。在此基础上,采用了相位补偿的方法来补偿直流滤波电容和电流环造成的超前相位,降低了输入电流的总谐波含量,使功率因数接近为1。

Zero-Crossing Distortion in Single-Phase Boost PFC Converters Using Average Current Control

Active power factor corrected converters usually use an input filter capacitor to absorb the switching ripples and noises.The input filter capacitor current is very significant at the medium frequency(360～800Hz).The current of the input filter capacitor leads the input voltage by 90°,so that the power factor is very poor.At the same time the current loop introduces a leading phase at the medium frequency.This paper analyzes the effects of the DC input filter capacitor and the current loop and points out that the DC input filter capacitor is a very important cause of zero crossing distortion.On this base,the paper proposes a method to cancel the leading phase of the capacitor and the current loop,and to reduce the total harmonics distortion and make unity power factor approximately.