脉冲序列控制CCM Buck变换器低频波动现象分析

Analysis of low-frequency oscillation phenomenon in the pulse train controlled buck converter

报道了脉冲序列(pulsetrain,PT)控制电感电流连续导电模式(continuous conduction mode,CCM)Buck变换器中存在的低频波动现象,研究了其产生机理和抑制方法.时域仿真结果和输出电压与电感电流的相空间轨迹图表明,输出滤波电容等效串联电阻(equivalent series resistance,ESR)是影响PT控制CCMBuck变换器控制性能的重要因素.当ESR值为零或很小时,PT控制CCMBuck变换器将出现由于输出电压调整不及时而呈现的低频波动现象;随着ESR的增大,PT控制CCMBuck变换器工作在混沌状态,控制器能够及时调整输出电压,低频波动现象得到有效抑制.实验结果验证了理论分析和仿真结果的正确性.

In this paper,the low-frequency oscillation phenomenon in a pulse train（PT） controlled buck converter operating in continuous conduction mode（CCM） is found and studied.The mechanism of this low-frequency oscillation phenomenon and the way to suppress it are studied.The time-domain simulation results and their corresponding phase portraits indicate that the equivalent series resistance（ESR） of the output filter capacitor has a critical effect on this low-frequency oscillation phenomenon.When the ESR is zero or small enough,such a low-frequency oscillation phenomenon appears in the PT controlled CCM buck converter because the output voltage can not be regulated timely.With the increase of ESR,the PT controlled CCM buck converter operates chaotically.The output voltage can be regulated timely and such a lowfrequency oscillation phenomenon can be suppressed effectively.Experimental results are provided to verify the theoretical analyses and the simulations.