一种功率因数校正电路的分析与实现

Analysis and Realizion of a Power Factor Correction Circuit

介绍了一种用普通开关电源专用集成电路控制块作为控制电路，以升压式变换器作为功率电路的功率因数校正电路。该电路的输出直流电压经采样、误差放大作为电流基准，将Ｂｏｏｓｔ功率开关电流与电流基准比较，当功率开关电流瞬时值小于电流基准时，用专用ＩＣ发出的给定宽度脉冲驱动功率开关；反之，将提前关断功率开关。当负载变化时，电流基准也变化，从而保证了输入电流波形跟踪输入电压波形和输出电压的稳定。本文提出了该电路输入电流的计算方法，编制了分析程序，分析了输入电流的谐波含量，并计算了电路的输入功率因数。得出了在占空度为０．５时获得最大功率因数的条件，提出了获得最大功率因数时电路参数选择的一般原则。同时指出了该电路符合ＩＥＣ５５５－２标准的功率范围。

Describes a power factor correction (PFC) circuit,in which the power circuit is a boost converter controlled general switch mode controller IC. In the PFC circuit the current to follow through the power switch of Boost is compared with reference current which is the output of error amplifier in output voltage regulation loop. When the current in power switch is less than the reference value, the power switch is driven with the pulse given width from controller IC; Otherwise, power switch is driven with a shorter width pulse. The current reference changes with the variation of the load.In the result, the iuput current waveform tracks the input voltage waveform and the output voltage regulation is obtained. The author has pressented a computation method of the input current, and compiled a analysis program, and analyzed the harmonic companent in the input current, and calculated the input power factor and obtained the conditions of the maximum power factor for duty cycle equal to 0.5. The general rule selecting circuit parameter for maximum power factor and power range fitting IEC 555 2 are shown.