How to account for different "ground" in LTspice?

Discussion in 'General Electronics Chat' started by Obanion, Dec 9, 2010.

  1. Obanion

    Thread Starter New Member

    Nov 26, 2009
    24
    0
    Hi guys,

    I'm in the process of trying to simulate an interleaved boost converter in LTspice but I'm having trouble with the simulations.

    As an example, in this picture they have the AC line input with a different ground:

    http://powerelectronics.com/images/feat5-0709-bridgeless-interleaved-fig02.jpg

    If I go to a really simple case and simplify it to a single boost, I get:

    http://img195.imageshack.us/img195/8659/boostc.jpg

    It seems like I am unable to boost the input voltage at all (it's actually a few voltage less on the output than on the input). Is there any way to compensate for this to make the simulation accurate? Please pardon my lack of knowledge, but is this referred to as a floating ground?



    Any suggestions?

    Thanks!


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  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You don't show the parameters used for V1.
    M4 is limited to 33 Watts - did you know that?

    V4's negative side should be below M4's drain. As it is now, you have infinite current through L1, as L1 is a short across V4.

    D1 is simply a default diode. You should use a model.

    Rload is only 50 Ohms. You'll need more than 2A current through D1 to see more than 100v across Rload.
     
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