Cascaded Buck Converter: A Reexamination

Cascaded buck converter has been widely reported in the power electronics literature. The main features are a high voltage step-down ratio and large regulation range. Modeling of this converter has been also reported for a two and $n$ stage cases. Continuous conduction mode (CCM), same switching commutation instant $(\mathbf{D}_{1}= \mathbf{D}_{2})$, and similar behavior than a single buck stage have been considered to size its parameters. In addition, it has been reported that once a duty cycle is close to 0 or 1, a degradation of the output voltage and inductor current take place. However, a little effort has been done to correctly size its parameters when they commutate at the same or different switching rates $(\mathbf{D}_{1}=\ \mathbf{D}_{2},\ \mathbf{D}_{1} < \ \mathbf{D}_{2},\ \mathbf{D}_{1} > \ \mathbf{D}_{2})$, and it maintains a final voltage step-down ratio. Therefore, this paper reports the design stages to size its parameters in CCM for the overall cases $(\text{D}_{1}=D2, \mathbf{D}_{1} \text{D}_{2})$. Numerical simulations for a two stage $100\text{W}$ buck converter are reported.