Parameterizing SMPS's-choosing the right L,C, and switching frequency for Boost converter

Discussion in 'Power Electronics' started by Electronics117, Nov 3, 2018.

  1. Electronics117

    Thread Starter New Member

    Sep 9, 2017
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    I'm trying to find resources for designing my own boost converter, I have a super high level understanding of boost, buck, push pull and fly back DC-DC topologies but have no idea how to select the inductor and cap and frequency for a boost converter. If anyone has a suggested resource or would like to go back an forth with me that would be much appreciated. My school has plenty of caps, but only has a drawer that says "chokes" on it for inductors. I was planning on using a function generator for the pwm and boost like 7 volts to like 10 or 14. I have built a Pspice of what I have to work with but can't seem to manipulate it to what I want to happen, and I could simulate all of this but I want to use it as a prop for a presentation I'm working on (plus I don't think its good that I don't know this). Thanks!
    Ill attach a picture of my set up and a pspice I've used too.
    (I would upload actual pspice but it keeps glitching and I think its too big)
     
  2. Papabravo

    Expert

    Feb 24, 2006
    11,709
    2,468
    I would start with a boost converter IC. Get the datasheet, study it in detail, and follow the recommendations for component selection. Then I would lay out a PCB. You can breadboard this stuff, but that sometimes leads to unpredictable results. Use the PCB(s) to experiment with other component selections. Now you have a foundation for doing the second and successive iterations. Don't expect to hit a home run on your first at bat.
     
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  3. Electronics117

    Thread Starter New Member

    Sep 9, 2017
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    I still haven't studied parameterization but I did get the circuit to work open loop so I definitely wanted to share that. Even with the inductor I had.
     
  4. Sensacell

    Moderator

    Jun 19, 2012
    1,989
    618
    I second the warning about bread boarding.

    When working with switching regulator chips- throw away your solderless breadboard.

    Many modern high performance converter chips will go haywire if you try to test them on a sketchy breadboard.
    Due to the high frequencies and currents involved, the layout is critical.

    The part data sheets usually have a section called "PCB layout considerations" - ignore this at your own peril.
     
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  5. Electronics117

    Thread Starter New Member

    Sep 9, 2017
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    Nvm

    "what thing is not like the other!???" xDD
     
  6. Electronics117

    Thread Starter New Member

    Sep 9, 2017
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    0
    Got it xDD
     
  7. MrAl

    AAC Fanatic!

    Jun 17, 2014
    5,283
    1,136
    Hello,

    If you have no other constraints then you would go with the highest frequency you can get away with because the higher the frequency the smaller the inductor and cap physical sizes. If you are stuck with a certain set of inductors though then you have to figure out what frequencies those inductors will work well at. You also have to realize that could limit your design severely because for one thing the inductor ESR plays a big role in efficiency and in the case of the boost converter even the highest output voltage that can be achieved for a given load.
     
    Last edited: Nov 10, 2018
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