一种低输入纹波电流的反激变换器

A Flyback Converter with Low Input Ripple Current

针对开关变换器输入侧固有的断续纹波电流带来的电磁干扰、缩短输入源寿命等问题,以反激变换器为对象,提出了一种无源纹波补偿电路。该电路由变压器、二极管、电解电容组成,在所设计的纹波抑制条件下,其工作在类似反激状态,产生补偿电流,有效地抑制了输入侧固有的断续纹波电流。在阐其工作原理的基础上,运用公式推导了系统增益、纹波电流抑制条件以及相关变量的参数计算方法,搭建了一台60~80 V输入、额定输出电压30 V、额定功率65 W的实验样机,实验结果验证了所提无源纹波补偿电路的可行性及理论分析的正确性。

Aiming at the problems of electromagnetic interference and shortened service life of input source caused by inherent intermittent ripple current on the input side of switching converter, a passive ripple compensation circuit for flyback converters is proposed. The circuit is composed of transformer, diode and electrolytic capacitor. Under the designed ripple suppression condition, it works in a similar flyback state and generates compensation current, which effectively suppresses the inherent intermittent ripple current on the input side. On the basis of explaining its working principle, the parameter calculation methods of system gain, suppression conditions of ripple current and related variables are deduced by using the formula. An experimental prototype with60 ~80 V input, 30 V rated output voltage and 65 W rated power is built. The experimental results verify the feasibility of the proposed passive ripple compensation circuit and the correctness of theoretical analysis.