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Discussion in 'Electronic Design' started by Nitin Skandan, Jan 6, 2004.

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  1. Dear friends,

    I am working on project to design IGBT based inverters for railway
    rolling stock. I need some help with reagrd to design of inverters.I
    have to make 3 inverters of following specs.
    1) 5KVA (single phase)
    2)25KVA (3 phase)

    I came across Intelligent power modules with IGBT packs and assciated
    circuitary ready to be used in inverters once you have a firing board.
    Is this the best and easiest way to do it? Any body know similar
    modules for single phase inverters.

    Thank you

  2. R.Legg

    R.Legg Guest

    There's a limit to the intelligence of IPMs, that you will have to
    supply to ensure their successfull application.

    Once you've determined what kind of power source, load and application
    is involved, you can look for a suitable controller and drive

    'Rolling stock' have converter requirements that may have nothing to
    do with actual direct traction drive. Both AC, DC and hybrid systems
    are used.

    There are interesting articles covering inverters at these and higher
    power levels, published by the University of Wisconsin (WEMPEC):

    and also in EPE and IAS conference records:

  3. Thank you Legg for helping me out.
    I have a few more doubts .
    I relatively new guy in feild of power electronics so doubts may seem fundamental.

    I have to make a 230 V Single phase50 HZ inverter with input 110VDC.
    so i am do somthg like this

    110V DC -> DC link ( to step up) ->IBGT module with Multiple PWM board

    output is monitered and width of pulse is changed to keep 230V at output.

    Are my intentions clear?

    IS DC link necessary to step ut DC so that output is 230V

    thank you
  4. R.Legg

    R.Legg Guest

    The use of the DC link has advantages if the source is finicky and the
    load absolutely must be driven by the higher voltage, but it is
    obviously not what you'd do if you were attempting to make a
    commercially competative machine to run on a 110DC distribution

    The 110DC system has the distinct advantage of already being there
    without a conversion step. It also interfaces nicely with such
    commercially cheap energy storage and smoothing elements as batteries
    and double-layer capacitors.

    Generating suitable AC voltages from this lower voltage, for suitably
    wound motors and loads, is practical at the power levels you are
    addressing, using no elaborate technology. Though it will not be
    competative with systems designed for higher voltage distribution
    systems, it will certainly outperform anything kludged together to
    make higher-voltage hardware run on the lower voltage system.

    If this is not your decision to make, then rest assured that most
    hare-brained ideas from above can be made to function, given
    sufficient resources and a captive market.

  5. Hi ...

    Thank u Legg ..

    after some discussiion and reading i have finally setteled for a
    systenm like this..

    I have to make 5KVA, 10KVA and 25KVA inverteres for use in railway
    rolling stock applications
    110VDC input and 230V/410V 50HZ ac output.

    we are plannin to go for 4pack and 6 pack IGBT modules with built in
    driver chips in the pack. We all ready have a power controler
    producing PWM outputs based on TMS320 DSP series .

    We are planning to use sinusoidal PWM . Output will be stepped up at
    the output of inverter using suitable transformer.

    Single phase we wioll use Full bridge setput
    and 3 phase we use 6 step inverter.

    is everythg okay


    Nitin S
  6. hello Legg

    I have one more doubt regarding generating 230VAC from 110VDC
    we are planning to step up the output of inverter using transformer
    for accomplishing this. The load draws almost 85 Amps . will this make
    the transfromer much bigger. Our inverter must as compact as it can
    get. How can this be attained. Is there a good way other than
    transformer method.


    Nitin S
  7. R.Legg

    R.Legg Guest

    Give me a break.

    100VDC systems should be addressed as such.

    If you insist on trying to make it look like something else, you are
    making that decision on your own. At this power level, conversion from
    100V to 400V will have cost and efficiency implications that will not
    be recoverable.

    The use of a transformer in this initial conversion is not an
    automatic assumption, unless a system 0V or neutral through-wire is
    intended to be preserved for safety or hardware configuration
    considerations. Auto-transformers or DC boost circuits could be
    cheaper and more efficient, if your loads can tolerate floating
    reference voltages.

    If a transformer IS used, you should make it do as much of the work as
    is possible, providing every single voltage required to enable
    downstream circuitry to be as simple and as cheap as is possible.

    If your aim is to allow conversion to a higher voltage system in the
    future, without major modifications, then you will not be able to do
    this. Instead you will have to include every single bell and whistle
    needed for the higher voltage application, and the transformer becomes
    simply dead weight.

    You shouldn't configure your entire development program to justify a
    single, possibly mistaken, preliminary hardware purchase (of a
    controller). I have no doubt, however, that this controller could be
    re-programmed to provide suitable performance in any hardware, at any
    voltage required of that hardware, including 110VDC.

    Though 110VDC traction has been only rarely used in the past, you
    might find that current developments in HEV technology make it
    increasingly attractive, if you take the time.

    Have you done ANY research into this issue?

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