Buck DC/DC变换器的输出纹波电压分析及其应用

Analysis of Output Ripple Voltage of Buck DC/DC Converter and Its Application

为使Buck变换器以较小的电感达到期望的输出纹波电压指标并满足本质安全要求,在输入电压?负载构成的平面上,按电感的取值将Buck变换器划分成四个工作区域,求出其在各个区域的输出纹波电压极大值;指出在变换器输出电流最大的情况下,如果电感的取值使得变换器在输入电压最低时处于连续导电模式(CCM),而在输入电压最高时处于不连续导电模式(DCM),则输出纹波电压极大值最高;最小负载电阻和最高输入电压所对应的CCM和DCM的临界电感,即为整个工作范围内使输出纹波电压极大值最低的最小电感。实验结果验证了理论分析的正确性。

To reach the desired output ripple voltages （ORV） of a Buck DC/DC converter with a rather small inductance and especially to meet the requirements of the intrinsic safety, the operating region of the converter is divided into four parts on the input-voltage versus load plane according to the inductance of its inductor. As a function of inductance, the maximum ORV （MORV） in each operating region is deduced respectively. It is pointed out that the MORV reaches the largest when the inductance is designed to make the converter operate in continuous conduction mode （CCM） under the lowest input voltage and in discontinuous conduction mode （DCM） under the highest input voltage with the heaviest load. It is also concluded that the minimum inductance to guarantee the lowest ORV is the critical inductance of CCM and DCM under the highest input voltage with the heaviest load. The experimental results are in positive to the analysis showing the feasibility of the proposed methods.