If you throw in the inverting cuk converter, other 4th order topologies should also be included - SEPIC and Zeta. Both are non-inverting boost and buck.

Want to add isolated topologies to the conversation?

Is this a race to name every topology ever used?

 

Thank you for the clarification, Ron. I have been following Dr. Cuk since the early 1980's.

 

Hi Dick,
I did use Dr. Cuk's inverting supply like in post #20. I needed a negative supply and there was none. (neck of a CRT monitor) I could not have ripple current on the input or output side. With a well designed transformer the ripple current was very small. The thing I had not seen coming was the current in the MOSFET was much larger than I thought. Center capacitor had huge ripple current.

Cuk is a interesting "cat" with hard math and (for me) not much real world applications. I have spent a number of evenings with a calculator and a Cuk white paper. Good exercise for the head.

 

Agreed that he is a truly amazing and inventive engineer. I was intrigued with the concept of ripple cancellation actually working. Many of his formulas were not intuitive to me.

 

I wonder if the Cuk converter would have been more popular had he not patented it. After all, it's a circuit that we can manage without and it seems that is exactly what everyone did. Low ripple is its only real advantage, it's probably even slightly less efficient that the alternatives.

I managed to understand the ripple cancellation, but the concept of winding both the AC and DC magnetics on the same core I didn't quite get. And as it needed a weird-shaped core, I never tried it.