sci.electronics.design

Read a little about isolated Cuk converters. Why are they not used instead of Buck, boost, Buck-boost converters? They work best with CCM but can of cause also use DCM. The original patents are expired:

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The 1:1 transformer is gapless. The input/output-transformer must have a gap:

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Cuk topology is current loading/dumping, which means both input and output ripple is a lot easier to tame. Hey there is an inductor for "free" in series with the input and output.

( Here only the basic unisolated Cuk is described:

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I have only found one (non-isolated) Cuk chip:

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It is even possible couple the input/output inductor to (almost) zero input ripple.

The "worst"/"impossible" Cuk to design seems to be the Integrated Magnetics Cuk Converter (IMCC, "DC transformer") because of "the two RHP zeros". Why is that a problem? Can the control be some AI? In DCM a each cycle can be done separately so you have full control? Note: The IMCC is the 1:1 transformer and input/output-transformer integrated.

It is called a DC transformer because of (almost) zero input and output ripple".

boostbuck.com: Easy Design of the Boostbuck Family of Converters: Beef:

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Quote: "...Gus: I visited Dr. Cuk at his Irvine laboratories not long ago--he is an old mentor and friend of mine. He told me himself that the original patents on his converter had expired. His company has patents on further mods to the topology still in effect, but the original topology is no longer patented. It is this original that I deal with on my site...Gus: Nothing on my website is patented..."

home.netvigator.com: Cuk converter:

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Citat: "...The Cuk converter is a new SMPS topology at this moment. It include higher efficiency, low input and output current ripple, minimal RFI, small size and weight..."

T.S. Finnegan (January, 1991). "Cúk: the best SMPS" (på English). Electronics World & Wireless World ISSN: 0959-8332 Discontinued in 1995. Continued by Electronics World (ISSN: 1365-4675).: pp.69--72. Look at table at page 71. Quote: "... The table below gives the effective primary and secondary copper losses, and the transistor and diode stress levels for the three types of converter, operating under identical conditions, for three different output voltages. The Cúk converter is more efficient and has lower stress levels in almost every respect ..."

Terrence Finnegan (July, 1991). "Design brief: 60W Cuk converter". Electronics World & Wireless World ISSN: 0959-8332 Continued by Electronics World (ISSN: 1365-4675).: pp.596--600.

?uk, Slobodan; Middlebrook, R. D. (June 8, 1976). "A General Unified Approach to Modelling Switching-Converter Power Stages" (PDF). Proceedings of the IEEE Power Electronics Specialists Conference (Cleveland, OH.): pp.73-86:

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Glenn

I saw someting very similar used to generate/regulate the Vs source in a pl asma TV. Then main advantage I see in such a circuit is much lower peak cur rents. Within its limitations I think it is useful for quite a few things, but I doubt it would be the best choic for something with wildly changind c urrent demands when you want the voltage to e regulated rock solid.

Of course that closely describes just what is needed for the Vs in a plasma TV and they made it work. I think part of the reason they chose it is beca use they are dealing with so much EMI in those things it is ridiculous. I m ean, when you look at a flat panel TV and it has a metal back cover, it is a plasma, not an LCD. They would not use one ounce of metal if they could a void it but they have no choice. There is even a conductive glass screen in front with grounding fingers all the way around it. I'm pretty sure it is also a UV filter. Don't break them things, they look expensive.