Non-inverting Cuk Buck Converter

Is this not a thing? Is it merely because it's equivalent to a regular buck that has with fewer parts?

Consider the standard inverting nonisolated Cuk configuration:

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Consider the junction of the switch and diode: Is + Id is continuous (give or take inductor ripple and switching transients), and positive. (Which, by the way, is fantastic for a ground referenced shunt resistor, for an average current mode converter.) Suppose we ground the output instead (R = 0), and disconnect these from ground, so that Is + Id feeds a new load node (and R_L).

Is this not better, because it has continuous current flow on all three ports (input, positive output, and negative output)?

The key is that C sees full ripple, just as the input cap on a buck, or the output of a boost. It's still not perfectly equivalent, though: C acts against leakage inductance, whereas in the vanilla configuration, you must add an extra inductor for that purpose (say to get a 2nd or 3rd order lowpass response).

Tim

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Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
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Tim Williams
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