Solar Boost Converter

Discussion in 'The Projects Forum' started by snakub, Sep 29, 2013.

  1. snakub

    Thread Starter New Member

    Sep 29, 2013
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    Hi I have two solar panels on the back of my electric truck that put out 36 volts at 8 amps each and I need to step up that voltage to my pack voltage of 120 volts. Do they make a dc to dc converter possibly with mppt for this application?
     
  2. #12

    Expert

    Nov 30, 2010
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    ...not likely. These are 2 very different jobs. Just from curiosity, are you wanting a MMPT for a moving truck? That would be very special!
     
  3. snakub

    Thread Starter New Member

    Sep 29, 2013
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    Yes they are already mounted and hinged on the back of the truck all that is missing is the electronics to step the voltage up. I have a tl494 chip but I don't know everything about it and I tried messing with a toroid and an arduino last night to find the appropriate frequency for the toroid but the mosfet kept getting hot.
     
  4. #12

    Expert

    Nov 30, 2010
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    Probably need to polish the drive signal to the mosfet. Post your circuit.
    Meanwhile, I'm asking a Moderator to move this to, "Projects" so more people are likely to know what to expect about what you need.
     
    Bernard likes this.
  5. ronv

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  6. snakub

    Thread Starter New Member

    Sep 29, 2013
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    I was just switching a toroid on and off with a mosfet with this code with an arduino
    Code ( (Unknown Language)):
    1. void setup () { pinMode (2, OUTPUT);} void loop() { digitalWrite(2,HIGH); delayMicroseconds(50); digitalWrite (2,LOW); delayMicroseconds (15); }
    The mosfet kept getting hot even when I put a fet driver to it the fet actually drew so much current that the arduino shut down my usb and turned my computer off. How do I know when I am at the right frequency and how do I keep from blowing fets? The toroid is about 2 1/2 inches and the primary is 12 windings and the secondary is 48 windings. I can't believe in this day and age there's not something I could just buy....
     
  7. ronv

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    Nov 12, 2008
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    It's a little more complicated than that. Have Google for boost converter.
    Can you program your micro for MPPT?
    You didn't like Post 5?
     
  8. snakub

    Thread Starter New Member

    Sep 29, 2013
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    Ah I didn't see post 5! How do you know it would be 300 dollars? No I wouldn't know what sensor to use for voltage feedback to the micro. I haven't been able to find a boost converter in my voltage range but I have found some in the wattage range, Mppt is nice but its not absolutely critical. If you could find one in my voltage range that would be great but I have not been able to.:(
     
  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    36v at 8A x2 (16A) is about 600W.

    A 600W boost SMPS is not a trivial project! For any decent efficiency you need a push-pull driver and SMPS transformer good for >600W.

    This is not the type of project for someone "messing with a toroid and an arduino". :eek:
     
  10. snakub

    Thread Starter New Member

    Sep 29, 2013
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    I know that's why I kept asking if there was something I could just buy. If not though I wouldn't use an arduino I would try to use a dedicated chip like the tl494 with very oversized components.
     
  11. ronv

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    It was in some other literature, but it is also in the drop down box for pricing.
     
  12. snakub

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    Sep 29, 2013
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  13. #12

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    Kind of like this:
     
  14. snakub

    Thread Starter New Member

    Sep 29, 2013
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    How exactly does that circuit with the 7812's work? I thought the 7812 stepped the voltage down linearly and there was a lot of inefficiency with it.
     
  15. ronv

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    You probably need some kind of charge controller as well. What kind of batteries?
     
  16. snakub

    Thread Starter New Member

    Sep 29, 2013
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    Just lead acid for now but what kind of a charge controller would I have to have if I'm going to go with a different chemistry? What about just a state of charge shut off switch that turns a relay off when the batteries are "full"?
     
  17. #12

    Expert

    Nov 30, 2010
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    First you have to find out how much current the DC to DC converter needs, then design a switching converter for that much current.
     
  18. snakub

    Thread Starter New Member

    Sep 29, 2013
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    So does anyone know how to correctly use the tl494 for this application? Like if the secondary on the toroid absolutely needs a center tap just like the primary for voltage sensing p.p.t.? Or can I just go off of one of the leads of the secondary? I need details total newb here!:confused:
     
  19. #12

    Expert

    Nov 30, 2010
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    You couldn't possibly understand how much you are asking for.

    "Total newb" to "state of the art", with all the bells and whistles you can think of, and every wasted milliwatt minimized, where even the length and width of the traces on the circuit board have to be optimized, is asking an unpaid volunteer to spend weeks walking you through every millimeter of this job, when you could buy most of it "off the shelf", and the retail version would work better, cost less, and be more reliable than anything you could assemble.

    That said, I eagerly await the next person that wants to step up to this challenge.
     
  20. snakub

    Thread Starter New Member

    Sep 29, 2013
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    I have asked for something off the shelf already ( the simplest solution) and no one has ponied up. I haven't been able to find it. I am not asking for every detail of the tl494 just a basic overview and a few headsups and gotchas and I'll just try and take it from there. Even if there is an off the shelf solution and that solar place never got back to me I left multiple messages and called no answers.
     
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