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High voltage current and voltage sources

Discussion in 'Electronic Design' started by James Rollins, Apr 12, 2009.

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  1. How difficult is it to make a compact transformerless high voltage
    current and voltage source? Is it possible to adapt the current
    topology with properly rated components and achieve this affect or
    modify existing low voltage techniques with such components?

    For example, suppose I want a current source of around 1mA with a
    1000V compliance. Could I adapt an LM317(or variant) to drive a
    capable BJT for such loads?

    http://en.wikipedia.org/wiki/Current_source

    Shows many basic topologies for current sources and it is my belief
    that ideally they all work for any voltage and current. Is this
    correct? Is my problem dealing simply with component capabilities and
    isolation issues?

    Similarly, for switched mode topologies such as a buck-boost if I were
    to use capable components(high voltage ratings) and diligently deal
    with isolation issues could I expect to have success?

    Potentially my issues lay with finding the properly rated components
    or finding exotic methods to modify existing components for such
    capabilities?

    Alternatively, are there any high voltage IC voltage and current
    sources?

    James
     
  2. I failed to mention some of the specs: DC, continuous operation,
    maximum 1000V, maximum 10mA-1A. At this point I'm only worried about
    the low end current range of about 10mA but in the future I do believe
    I might need possibly a 1000W supply
     
  3. Guest

    The short answer is that it is possible, but it would take a
    complicated, bulky and expensive circuit. Anybody who took the job on
    would want to know a lot more about what you were actually trying to
    do, and why.

    If you don't want to publish the kind of detail in a public forum, you
    are welcome to e-mail me directly (the adress I post under here -
    bill.sloman at ieee.org - is real and works). It's unlikely that I
    would be able to do the job for you but I've got a couple of private e-
    mail adresses that might be able to help.
     
  4. MooseFET

    MooseFET Guest

    Why do you want it to be transformerless?

    How big is compact?

    At 1000W it likely has to be mains powered. What is the mains
    voltage?

    What does the load look like?

    Can the output terminals look capacitive?
     
  5. James Arthur

    James Arthur Guest

    Fairly large, if it includes surface and airflow for extracting
    1kW worth of heat.

    A transformer would be smaller.

    Cheers,
    James Arthur
     
  6. whit3rd

    whit3rd Guest

    Define 'transformerless'; a Model T spark coil generates high
    voltage, it's CALLED a coil but it's also an autotransformer.
    An LM317 requires several milliamps output current for normal bias,
    so it won't do the low current range. As for high voltage, you can
    get
    amplifiers (grounded-base transistor) that take current at low voltage
    as input (emitter current) and generate current at high voltage as
    output (collector current). That means you can potentially separate
    the 'current regulate' and 'high voltage' problems.
    There are (currently on the market) no good references for high
    voltage; the Zener diode, or bandgap reference, or integrated circuit
    regulator using them, will be a part of your low voltage section.
    There ARE some high voltage ICs, but unless you're manufacturing
    motor controls it's unlikely you can find ones that do what you want.
    Integration doesn't, in and of itself, constitute a virtue.

    I've used 4.5 GV systems, which qualify as 'exotic'. Most of the
    1kV-and-under electronic field seems ... domestic... to me.
     
  7. MooseFET

    MooseFET Guest

    MOSFETs as common gate stages work too.
     
  8. Sorry for not being clear and thanks for the replies.

    I want to create several power supply from mains(110V or 220V AC) to
    ~0-1000V DC @ 10-100mA. I need several *variable/programmable*
    voltage and current sources in the same housing. Weight is a big issue
    but temperature/heat is not if within reason. These sources need to
    operate continuously.

    The initial supply can actually be from DC by using a large
    transformer rather from mains if need be. Ripple is not a huge issue <
    1-3%. Size is important but secondary to weight. The loads is mainly
    resistive but with with some capacitance probably less all less than
    1nf.

    I believe that any standard topology used for for standard
    microelectronics projects, if adaptable to the higher voltage, would
    work fine. I am drifting towards using a simple switching topology.

    http://en.wikipedia.org/wiki/Split-pi Seems like it would work fine if
    using igbts and give me the variability/probability I desire and
    somewhat lower in weight than an equivalent transformer based system.

    Also, of course is the standard http://en.wikipedia.org/wiki/Flyback_converter
    ..

    Again, regulation is not necessarily an issue as I can do it before
    the power supply so a simple linear attenuation could work, at least
    for prototyping. Switchers seem to be the way to go though. My
    question is, would it be difficult to adapt such topologies to the
    voltages I require? As far as I can tell I would just have to find the
    rated components? Is this correct?

    Thanks,
    James
     
  9. Fred_Bartoli

    Fred_Bartoli Guest

    "whit3rd" <> a écrit dans le message de
    4.5GV ?

    With spice I can deal with that everyday, but is that really GV?
    I can think of MV, but GV...
    What was that?
     
  10. Fred_Bartoli

    Fred_Bartoli Guest

    Uh, how can this have been granted a patent?

    Is the next step patenting a two stages resistor divider?
    Well, no it can't now. I've just made it public domain...
     
  11. whit3rd

    whit3rd Guest

    It was an ultrarelativistic synchrotron, SPEAR by name.
    Basically a vacuum tube with a bunch of trapped electrons
    (positive electrons, usually) going in circles.

    Individual kinetic energy of the positrons was routinely set
    at 4.5 GeV, there weren't actually any static fields that
    were creating such a large potential difference.

    The power supply was a two-mile-long linear accelerator...
    strung out collections of megawatt power klystrons...
    like I say, exotic. The best part was the safety orientation,
    all about the various safety features (4 foot concrete for
    radiation shielding; alarms for: hydrogen leaks, earthquake,
    and radiation; interlocks that could shutdown the whole
    two-mile linear accelerator if your doors weren't shut).
     
  12. Fred_Bartoli

    Fred_Bartoli Guest

    "whit3rd" <> a écrit dans le message de
    OK, I surrender with my very modest 30keV accelerator (but I guess you
    couldn't display as beautiful images as I could with mine).
    But now that I've switched to LCD, kinetic energy is even more depressingly
    low...
     
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