DC Voltage Regulation with High current

Discussion in 'The Projects Forum' started by Jonnap2000, Oct 7, 2009.

  1. Jonnap2000

    Thread Starter New Member

    Oct 7, 2009
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    Hi all,

    I have a project where i need to regulate the voltage from a non regulated Power Conditioning Unit from 35 V down to 28 V.

    The input to the PCU is 435 V AC, 3 phase with a 50 A circuit breaker from the wall out put.

    The output from the PCU is aprox 35 V 300 Amps. This is connected to a military vehicle slave socket (NATO).

    We would like to regulate the output to 28 V, 300 Amps with as little tolerance as possible and a surge of 600 A. The PCU will be used to run the military vehicle when the main engine and alternators are not running.

    Thanks for your help.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Sounds like a supply for one of the Transformers, or your personal tank.

    A 300 amp regulator is not easy to come up with, especially when it's regulating a regulator. Do you have a schematic of the PCU? The circuitry can handle the current, so altering it to output a lower voltage might be a better approach.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    You should be looking for a commercial 3 phase AC powered supply that puts out a regulated DC voltage directly. At these power levels, this task is beyond a homebrew solution.
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    35V-28V = 7V @ 300A. The series regulator will have to dissipate 2.1KW.
    I donno what can handle that power, but the latest trench FET's or IGBT's.

    Still 2.1 Kilo watts as heat is still unthinkable for series regulator, you need to go for switch modes.

    Beenthere suggested the best method.

    Rifaa
     
  5. Jonnap2000

    Thread Starter New Member

    Oct 7, 2009
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    Hi Beenthere, i have a circuit diagram of the PCU if that is what you mean. The publications for the PCU are hard to come by as it is a one off "green box"

    Can you elaborate on the use of a switch mode power supply. I am a little rusty when it comes to power management.

    Cheers
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    Try posting the circuit diagram. If that can be altered to lower the voltage out, then life is much easier.

    Very briefly, a switching power supply operates with higher efficiency than a linear one. The linear supply uses pass elements that act like controlled resistances to maintain a constant output voltage. They have to dissipate a lot of heat. Switcher pass elements operate rapidly, and are on or off, minimizing losses.

    300 amps is still a lot to handle.
     
  7. aboamal

    Member

    May 29, 2008
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    you can use PMW circuit to regulate the DC voltage
     
  8. Jonnap2000

    Thread Starter New Member

    Oct 7, 2009
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    It seems that the vehicle has two alternators that produce 300 A. Would it be feasable to that the regulation circuitry of the alternators and use them to regulate the external PCU. I know it is AC/DC for the alternators but would not be a case of removing the rectification stage?

    Who hard would this be?

    Many thanks for all your help.
     
  9. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Curious what kind of vehicle is it? Which military?
     
  10. Jonnap2000

    Thread Starter New Member

    Oct 7, 2009
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    Sorry, i cant divulge that information. I know it would help if you knew but i may get into a lot of trouble.

    Sorry, but many thanks.
     
  11. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    No, because to control an alternator, you only have to control the field winding. The current in the field winding of an alternator is usually about 1/20 to 1/50 th of the output current, so the vehicle's VRs are rated at most for about 15A.
     
  12. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Ok, so your military has no technicians or mechanics? :rolleyes:
     
  13. Jonnap2000

    Thread Starter New Member

    Oct 7, 2009
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    They have but we dont have anyhere at the minute. I am only an vehicle electrician. Knowledge is power!!!

    Many Thanks
     
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