一种单级高频AC-AC变换器的低通输入滤波器的参数设计

单级高频AC-AC变换器将工频电网电压转换为高频(一般大于100k Hz)正弦交流电压,并实现功率因数校正的功能。由于其功率因数校正单元工作于电流断续模式(DCM),使得输入电流含有大量高次谐波,需采用低通输入滤波器予以滤除。上述低通输入滤波器的滤波参数不仅影响其滤波性能,还会影响到输入功率因数等诸多方面,因此滤波参数的确定十分重要。首先,根据叠加定理分别建立变换器交流侧等效电路模型,即工频分量和开关频率分量单独作用下的等效电路;进而,根据滤波器输入、输出要求合理设置相关预设参数,使加入滤波器后电网输入侧满足能量之星关于功率因数的要求。在此基础上以LC低通输入滤波器为例,对输入滤波器参数的定量设计过程进行详细阐述,并归纳出一种程序化的设计方法;最后,进行仿真及实验验证设计方法的正确性,该方法也可用于单级有源功率校正器的输入滤波器设计,而且对设计其他类型的低通输入滤波器有借鉴价值。

Parameter Design of the Low-Pass Input Filter for a Single-StageHigh-Frequency AC-AC Converter

Single-stage high-frequency AC-AC converter transforms line voltage into high frequency (generally larger than 100kHz) sinusoidal ac voltage. Since the power factor correction cell operates in DCM, a large number of high-order harmonic currents appear. Therefore, low-pass input filter is needed to reduce harmonic currents. The parameters of an input filter not only determine its filtering performance but also have effects on its input power factor. Thus how to determine these parameters above is very important. In this paper, the equivalent circuits of utility frequency component and switching frequency component are presented respectively. And then some related preset parameters are set adaptively according to the input and output conditions of the filter, meeting the demand of Energy Star on power factor. Ultimately, taken LC low pass filter as an example, the parameters design procedure of the low-pass input filter is presented in detail and a programmed design method is concluded. The simulations and experiments are conducted. The results have verified the correction of the theoretical analysis. The proposed design method for low-pass input filter is also applicable for the single-stage active power factor corrector. Moreover, it provides an important reference to design other type of low-pass input filter.