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AC-AC Voltage Regulator

Discussion in 'Electronic Design' started by PFITZ, Apr 30, 2008.

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  1. PFITZ

    PFITZ Guest

    Hi,

    Just wanted to bounce a quick question out there as I don't have much
    experience in this field, but Is there a device that exists that will
    regulate an AC supply to a certain Voltage? I'm looking at
    incorporating this stage in a design at present.

    What I'm looking at currently needs to be only step-down. But if there
    are Buck-Boost types that would do also.

    Ideally I'd like to build something discretely to do this job, I want
    to regulate 50Hz ~240VAC down to 50Hz 180VAC.

    A trasnformer won't work because the input will see variations and I
    don't want these present on the output.

    If anyone can point me in the right direction, I'd be much obliged.

    P
     
  2. PFITZ

    PFITZ Guest

    Just to also add, I would need it to be capable of supplying >50A.
     
  3. There are AC stabilisers that use a resonant system, I think 1% is achievable.
    Cannot remember what those were called.
    No electronics is those.
    Oh, found it again: ferroresonant transformer
    This wikipdia link explains some of it:
    http://en.wikipedia.org/wiki/Voltage_regulator
     
  4. http://www.watfordcontrol.co.uk/prod_rotavolt.asp


    martin
     
  5. Phil Allison

    Phil Allison Guest

    "PFITZ"

    ** So you want greater than 9,000 watts from a 240 volt power outlet.

    And regulated.

    Keep dreaming.



    ...... Phil
     
  6. PFITZ

    PFITZ Guest

    Not continuously, the proposed product would be installed at the meter
    point, ie entry point to a house or apartment for the power. Is this
    completely impossible?
     
  7. Glen Walpert

    Glen Walpert Guest

    At your 9 kW power requirements you could use a custom constant
    voltage transformer, if you can find someone who still makes them, or
    a custom automatic tap switching transformer if you can stand the
    steps, or a motor generator set, or an adapted motor inverter with the
    optional output filter if what you want is three phase, or a custom
    inverter designed for your application.

    But I suggest you start by determining how much line voltage and load
    current variation you need to deal with, how much output voltage
    variation you can stand (none is not a reasonable answer), and how
    faxt it needs to respond to line and load transients.
     
  8. Phil Allison

    Phil Allison Guest

    "PFITZ"...

    Not continuously, the proposed product would be installed at the meter
    point, ie entry point to a house or apartment for the power. Is this
    completely impossible?


    ** Yawn............. . ................... ......................

    **** off you pathetic bloody TROLL.

    Phutttttttttt.............



    ... .. Phil
     
  9. MooseFET

    MooseFET Guest

    If the variation is slow, there is an electromechanical solution.
    They make them but I'm not sure where you can buy them. I will
    attempt to explain how they work:

    Imagine a 2 phase induction motor with a wound rotor. Imagine that
    one phase of the stator windings is connected to the incoming mains
    supply. Imagine that the other stator winding is shorted.

    Now imagine that the rotor winding is in series with the power going
    to the load and that you have some sort of handle that lets you turn
    the rotor. When you point the rotor one way it will add to the mains
    voltage. When you point it the other it will subtract. As you turn
    it, the voltage will vary smoothly between the two extremes.

    Now imagine that there are spings forcing the rotor to point in the
    direction that reduces the voltage and a solenoid that would pull it
    the other way when energized. We also need to add an dashpot
    (mechanical drag) to slow the motion of the rotor. Now imagine a
    circuit that energizes the solenoid any time the output voltage falls
    too low.
     
  10. Not continuously, the proposed product would be installed at the meter
    point, ie entry point to a house or apartment for the power. Is this
    completely impossible?

    =========================================================================

    A motorized variac or Powerstat and a controller will do the job if slow
    response is OK. It is a good solution where waveform and efficiency are
    importsnt.

    You can use a buck transformer with a 60 volt secondary to drop the voltage
    to 180 VAC, and it would only need to be rated 60 * 50 = 3000 VA. Its
    primary could be driven by a 3 kVA Powerstat, 240 VAC at 15 amps. Superior
    246 or Staco 2520 would work. Look on eBay for surplus or some cheaper
    Chinese versions. You can rig a motor and limit switches to drive it. The
    motorized versions are expensive.

    Paul
     
  11. Not continuously, the proposed product would be installed at the meter
    point, ie entry point to a house or apartment for the power. Is this
    completely impossible?

    ============================================================================

    You might also be able to use a solid state motor controller. You would
    probably need to tweak the settings a bit to get 180 VAC at 50 Hz, but it
    will provide good regulation. If you build your own, you could synchronize
    the phase and frequency with the incoming line, if anything on the load
    side requires that (such as electric clocks). For 9 kVA, a 15 HP controller
    will do the job, but it's hard to find a single phase model at that power
    level. It would need a hefty capacitor bank. But you could add a battery
    pack, and your product would also provide brownout protection and would
    essentially be a UPS.

    Paul
     
  12. Rich Grise

    Rich Grise Guest

  13. Guest

    A constant voltage transformer would do it, snag is they are expensive
    and unlikely to be the voltage you need so you would need a second
    transformer. You could possibly use an industrial inverter with a
    filter but that wouldn't be cheap either and would raise other issues.
     
  14. PFITZ

    PFITZ Guest

    Thanks for all the suggestions guys, especially that glorious insight
    from Phil.

    I've done a bit of research and was wondering why something like the
    regulator described in "Lee, Y.S., Chen, D.K.W., and Cheng, Y.C.:
    ‘Design of a novel ac
    regulator’, IEEE Trans. Ind. Electron., 1991, 38, (2), pp. 89–94" has
    not made it into mainstream production.

    (maybe it has and I just haven't come accross one)

    I'm going to do a little playing around and try to simulate some
    circuits and see what I can come up with before progressing. I'll let
    you guys know how I fare. Thanks again,

    Rgds,

    P
     
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