DC-DC Buck-Boost Converter Design Requirements

Discussion in 'Power Electronics' started by fadh9l, Oct 1, 2016.

  1. fadh9l

    Thread Starter New Member

    Oct 1, 2016
    25
    0
    I have a project to design a buck-boost convener, the input will be a solar cell with using Ultra-Capacitor as an energy storage system, and the output will be an LED lamp. What are the given requirements that i should to have from Solar Cell, Ultra-Capacitor, and LED in order to do the design, for example Vin, Vout, Iin, Iout, F, Voltage and Current Ripple, and etc? Also how to start designing? Give me an example if you have to design this.

    Give me the best solar type, LED type, ultra-capacitor type with their specifications in order to do the best design.
    How to calculate capacitor and inductor values?
    Can i choose any frequency i want or i have to calculate it?
    Can i choose any Voltage and Current Ripple or i have to calculate them?

    Thank U,
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    Why do you want to design one? That's like designing your own lightbulb or fuse. You can buy one ready-made far cheaper than you can make one.
     
  3. fadh9l

    Thread Starter New Member

    Oct 1, 2016
    25
    0
    This is my Senior Design Project.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    One specification I would shoot for is efficiency, to keep the LED lit as much as possible for the given solar panel. Since there is no battery to stabilize voltage, this means you will want to accept a broad range of voltages – down as low as possible – while still lighting the LED.

    Of course, I'm not your professor. All that matters is what they want.

    Personally, I would choose a solar panel with a higher voltage output, as opposed to lower voltage and higher current. My reasoning is that the converter is going to need some minimum voltage to operate. If that is minimum is small relative to the available voltage, the converter will operate more of the time, in marginal lighting. If your converter needs 2V and your panel can only make 3V in full sun, you'll have little room.

    I don't see much point to the capacitor, since it will only provide a small amount of run time once the light is gone, and will delay the light coming on until it charges to a sufficient voltage. If you're not required to use it, I'd consider dropping it or using only a modest size if it helps operation of the converter.
     
  5. fadh9l

    Thread Starter New Member

    Oct 1, 2016
    25
    0
    I will use Ultra-Capacitor as an energy storage system.
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    It won't buy you much. Do the math. If you really want to store energy, a battery is far better.

    I should add that you are effectively designing one of those landscape solar lights. Are you sure that is worthy of a senior project?
     
  7. fadh9l

    Thread Starter New Member

    Oct 1, 2016
    25
    0
    Yes for sure, because it is the first time that will be using Ultra-Capacitor as an energy storage system in like this project.
     
  8. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,791
    There is a reason that nobody is doing that. It makes no earthly sense to use an ultra capacitor in this way.
     
  9. fadh9l

    Thread Starter New Member

    Oct 1, 2016
    25
    0
    I will try it, and see if it works or not. But in my opinion it will work because ultra-capacitor is an energy storage system.
     
  10. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,791
    You are of course free to ignore the advice you asked for, but you might want to consider the grade you're going to get from pursuing this dead end project.
     
  11. 64C113M Abe.

    New Member

    Sep 13, 2016
    14
    0
  12. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    It will work, as long as your definition of "work" includes a very low amount of storage, at a varying voltage, for a high cost. @Papabravo is correct that these are good reasons that NO one is doing this, despite these devices being manufactured by hundreds of companies.
     
  13. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,290
    1,255
    This is your most important question. The specification.
    You need to decide things like how bright, how long must it shine without sun, etc.
    You need to know input voltage output voltage and current as well as frequency.
    You can choose it. Higher frequencies (within reason) result in smaller (cheaper) parts.
    You can choose, but it must make your LED happy.
     
  14. fadh9l

    Thread Starter New Member

    Oct 1, 2016
    25
    0
    Thank you.
     
Loading...