全桥整流LC滤波电路电感电流连续性判断方法

Estimation Methods of the Continuity of the Inductor Current in Full-bridge Rectifier with LC Filter

二极管全桥整流并经LC滤波是从交流电中获得低纹波直流电压的简便方法。滤波器和负载参数可能使电感电流工作在连续或非连续(导数不连续)状态。在非连续状态下,整流器的输出不再是标准的全桥整流电压,更严重的是它使得负载电压强烈地依赖于负载电阻,给设计和应用带来不便。将整流电压理想化,即用理想电压源代替整流电路,建立了判断电感电流连续性等效电路。通过分析该电路电感电流的变化规律,分别针对稳态和暂态情况,提出了判断电感电流连续性的工程近似方法,可用于校验滤波器设计。实验和仿真证实了判断方法的有效性。

Diode full-bridge rectifier with LC filter is a simple way to obtain the smooth DC voltage from AC system. However,the filter and the load may lead the inductor current to be continuous or discontinuous conditions. Under the discontinuous condition the output voltage of the rectifier will not be a standard full-bridge rectifier waveform anymore. But more important thing is that the load voltage will depend strongly on the load resistance. So it must become more inconvenient to design and apply this kind of circuit. An equiva- lent circuit used to estimate the continuity of the inductor current was built by substituting the rectifier with an ideal voltage source. Several approximate rules for estimating the continuity of the inductor current in both the steady state and the transit state were proposed by analyzing the inductor current of the equivalent circuit, which may be applied to verify the design of the filters. The validities of these estimation rules are demonstra- ted by the experiments and the simulations.