PIC16F877A Based MPPT Project (Help)

Discussion in 'Embedded Systems and Microcontrollers' started by Hakimos, May 23, 2015.

  1. Hakimos

    Thread Starter New Member

    Oct 14, 2014
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    Hello guys, i'm building a solar mppt charge controller (I'll implement Perturb and Observe algorithme on PIC16F877A). I've joined the schematic on PDF, can you tell me if my schematic is correct ? Thank you.
    I've tested the buck alone, it worked, i've added a pwm from pic to my buck (controlled with pot) and it worked too. Current sensor worked too but sometimes I get some weird values.
    I've never tested the whole circuit and that's why I'm here, I want to put all together on a PCB but i want to be sure that there is no mistake in my schematics.
    thank you and have a good day
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Hmmm!
    Wondering where the schema ended up !!!
     
  3. Hakimos

    Thread Starter New Member

    Oct 14, 2014
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    Lol sorry i just uploaded it.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Starting at IC1: A capacitor (C9) makes a very bad choice to power a linear regulator.

    If you add some connections to this part keep in mind you can't take power out of a part you need that same power to turn it on in the first place.
     
  5. Hakimos

    Thread Starter New Member

    Oct 14, 2014
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    C9 is just the ouput capacitor of the buck converter, it's used to reduce the voltage ripple.
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Not the way you drew it. You omitted the junction.
     
  7. Hakimos

    Thread Starter New Member

    Oct 14, 2014
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    Thank you ErnieM, is this the only mistake you can see in my schematic ? All others parts are good ? Thank you.
     
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Only? I highly doubt that.

    A typical PCB goes thru an average of between 2 and 3 respins before it works well enough for production. And that is after an initial breadboard.

    You have a good start at a first cut here. You don't have a package ready to go to PCB layout as you still lack a complete bill of materials defining the specific part you will use. Example: the LM358 comes in about 9 different packages; the exact part number will indicate that.

    I did note one other missing connection. To eliminate these stop using 4 way junctions in all cases. Make junctions at a T intersection and you will never miss a junction (or make one your design rules checker will miss).
     
  9. Hakimos

    Thread Starter New Member

    Oct 14, 2014
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    Hello ErnieM. Thank you again for answering me.
    I've already printed (at home with toner transfer method) a PCB containing this LM358 package and it perfectly fits.
    For the junction, i use the "eye" (on top left near the "i") button and i check connection, it seems to be okay.
    Thank you again.
     
  10. Hakimos

    Thread Starter New Member

    Oct 14, 2014
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    Do I have to add resistor to the Mosfet's gates ? (Between driver and mosfet) ?
     
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