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SMPS Cuk converters

Discussion in 'Electronic Design' started by Glenn, Jul 24, 2013.

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  1. Glenn

    Glenn Guest

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

    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:Ćuk_converter )

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


    It is even possible to couple the input/output inductor for (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, 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

    - Easy Design of the Boostbuck Family of Converters: Beef:
    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..." Cuk converter:
    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.

    Ćuk, 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:

  2. Glenn

    Glenn Guest

    Two important note:


    The (incl. isolated) Cuk converter can "easily" be modified to be
    bidirectional - just exchanged the diode for a power MOSFET - and some
    more control circuit.

    The second power MOSFET can also be used for


    It is even possible to make AC Cuk converters - and the patents are
    still active:

    Feb 1, 2008 Bridgeless PFC Boosts Low-Line Efficiency:

    Dr. Slobodan Cuk:

    Part 1:
    Jul 1, 2010, True Bridgeless PFC Converter Achieves Over 98% Efficiency,
    0.999 Power Factor:

    Part 2:
    Aug 1, 2010, True Bridgeless PFC Converter Achieves Over 98% Efficiency,
    0.999 Power Factor: Part 2:

    With schematic:
    Part 3:
    Oct 1, 2010, Single-Stage Isolated Bridgeless PFC Converter Achieves
    Over 98% Efficiency, 0.999 Power Factor:


    Application Characteristics of an Experimental RB-IGBT (Reverse Blocking
    IGBT) Module:

    A High Efficiency Indirect Matrix Converter Utilizing RB-IGBTs:

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