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150v DC-DC buck converter

Discussion in 'General Electronics Discussion' started by pellepuffin, Feb 15, 2016.

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  1. pellepuffin

    pellepuffin

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    Feb 15, 2016
    Ive looked on ebay for what seems like an eternity for a high voltage input, dc-dc buck regulator, finding nothing over 60V.
    Do anyone have an idea where I can find a buck regulator with max voltage input around 150V >50 watts
    If it can't be bought, what parts would be required in order for me to make one?


    It will be used with my 50 watt homemade mini wind turbine. I'm fairly new to this and well aware that building one would push my limits.
     
  2. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Hello
    Why does it need to be a buck convertor? What are you using this for. It concerns me that you are asking what parts would be needed to build one. What experience in high voltage electronics do you have?
    Thanks
    Adam
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    If you're planning to get power from your turbine (to charge a battery for example) then you want an MPPT regulator.

    This may have a similar topology to a buck converter but the control is different.

    If you use the battery under charge as the power source for the controller then only the pass device and the diode need to be rated for the higher input voltage.
     
  4. AnalogKid

    AnalogKid

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  5. pellepuffin

    pellepuffin

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    Feb 15, 2016
    I have no experiance of higher voltages. The converter would convert the peak 150v my generator is rated for. Since its only rated for around 50 watts the current is really small. After the regulator i will probably connect a solar charge controller, since they accept the lower voltages.
     
  6. pellepuffin

    pellepuffin

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    Feb 15, 2016
    The reason to why im not going for an mppt turbine charger is the rediculous prizetag.This is a small project with no real value. My idea was to use a converter and then feed it through a much cheaper pwm solar charger to benefit from overcharge protection etc.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Without MPPT a switch mode converter can drag down the voltage of your generator and reduce the available power to almost nothing.

    You'd likely be better off with a high power shunt regulator.
     
  8. pellepuffin

    pellepuffin

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    Feb 15, 2016
    Okay how does that work, what should i get? Don't know much about that kind of regulators
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    A simple shunt regulator is a zener diode.

    if you wanted 50V you could put a 50V 50W zener across the output of the turbine.

    Another alternative is a linear regulator. Both waste power.

    The zener has the advantage of keeping a load on the turbine so it will be far less likely to overspeed in high wind.

    In practice you wouldn't use a zener diode but a circuit employing a transistor which can dissipate more easily (and probably more cheaply).
     
    Arouse1973 likes this.
  10. pellepuffin

    pellepuffin

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    Feb 15, 2016
    So if I want to charge a 12V battery (using the shunt regulator) I will basically waste all the power that is generated at a higher voltage?

    If this is the case, then i've really gone and bought the wrong motor, since i will only be able to store about 10% of the power of which it is rated for.
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The problem is that with a simple buck regulator, it will attempt to draw more current as the input voltage falls in order to maintain the same output power.

    This works fine as long as the power demand is less than that available from the turbine.

    However the turbine tends to operate like a constant current source. Once you attempt to draw more power than is available the voltage falls much faster than the current increases.

    With a buck regulator a momentary reduction in input voltage causes an increase in current demand. If the turbine cannot supply this current the voltage falls. This in turn increases the demanded current which causes the voltage to fall further. The end result is that the input voltage (and with it the available power) collapses.

    This results in a stable state where the voltage remains low. It remains low until the power demand falls not just below the potentially available power, but below the power available at the lower output voltage.

    This is why MPPT regulators exist.

    An MPPT regulator is not too difficult to make yourself, and will effectively modulate the output power available to match the input power available.
     
  12. cjdelphi

    cjdelphi

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    Oct 26, 2011
    Simple switchers should allow slow startup, gradually soft startup (although a capacitor on it's reference pin should give that)

    The motor produces 110v low current DC? (Not AC)
     
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