峰值电流模式控制的非理想Buck变换器的建模

Modeling of Non-Ideal Buck Converter with Peak Current-Mode Control

在Ridley峰值电流模式控制的Buck变换器模型的基础上,提出一个包含传导损耗的修正模型。运用平均开关建模法,建立非理想PWM开关的非线性大信号平均模型,包含全部寄生电阻和二极管的正向压降。围绕某一稳态工作点,扰动并线性化平均模型,导出非理想Buck变换器的功率级在连续工作模式下的直流模型和线性小信号模型。在此基础上,修正峰值电流模式控制部分的小信号模型参数。最终建立整个峰值电流模式控制的非理想Buck变换器的线性小信号模型。推导小信号动态的解析结果,给出修正的补偿斜坡信号斜率。在Simetrix/Simplis开关电源软件包中进行了仿真分析,结果显示新模型能更准确地预测系统性能。

Based on Ridley＇s buck converter model with peak current-mode control. A updated model which includes all conduction losses is established. Using the averaged switch modeling approach, a non-linear large-signal averaged model of non-ideal PWM switch is derived, taking into account all parasitic resistances and threshold voltage of diode. Perturb and linearize it about a quiescent operating point,DC and small-signal model of power stage for non-ideal Buck converter in continuous conduction mode （CCM） is derived. Based on these, small-signal model parameters are modified for the stage of peak current mode control. At the end,a updated small-signal model with peak current-mode eontrol is extended for non-ideal Buck. The analytical results of small-signal dynamics and updated slope of compensation ramp are derived. Simulation is implemented in Simetrix/Simplis circuit analysis package. The results showed that the new model could predict system performance more accuratelv.