High power DC to AC inverter without transformer

Discussion in 'General Electronics Chat' started by ContraSpec, Dec 7, 2014.

  1. ContraSpec

    Thread Starter New Member

    Dec 7, 2014

    Im not sure if this topic is still open but i would like to build a pure sinewave inverter using some old thyristor packs from some motor softstarters, semikron - SKKT 92B & INXS MCC 95.

    Im new to inverters, but i do come from a electrical background and i do understand the risks involved in working with high dc voltages.
    please could someone assist me with a circuit diagram for pure sinewave inverter making use of semiconductor thyristor packs instead of mosfets/transistors/igbt's if that is possible.

    the project is to go fully transformer-less, using dc battery supply to whatever voltage required to make this work well (about 380 vdc input)
    • use either the Semikron SKKT 92 Amp or INXS 95 Amp thyristor packs,
    • yes i know i could purchase a commercial product, but the reward of building it is so much greater.
    • cooling for the thyristors wont be a issue as i have the heatsinks with forced cooling.
    • any means to log the input/output voltages/currents etc (arduino mega 2560) or ATMEL microcontroller chip?
    • control the inverter via the arduino? or ATMEL microcontroller chip?
    • load approx 5Kw peak @ 230vac, avg current @ 10amps. we have load shedding on our powergrid daily spanning for 4hrs at a time.
    • later i plan to add a solar pv and charger circuit with monitoring.

    any help would be appreciated.
    thanx in advanced
    kind regards
  2. Wendy


    Mar 24, 2008
    This was split from

    Welcome to AAC!

    A thread belongs to the OP (original poster). Trying to take over someone elses thread is called hijacking, which is not allowed at All About Circuits. I have therefore given you a thread of your very own.

    In addition, you have practiced the arcane art of necromancy, the revival of a long dead thread. Likely the OP (Original Poster) has solved his problem in the years that has passed, or thrown it away, or something.
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
    I'm not sure what you plan to use the scrs for. They don't lend themselves to DC circuits. Maybe you have a schematic?
  4. ContraSpec

    Thread Starter New Member

    Dec 7, 2014

    and thank you bill
  5. ContraSpec

    Thread Starter New Member

    Dec 7, 2014
    Hi Ronv,

    im starting a fresh, i dont have a schematic.
    the scr's come from thyristor motor soft starters, and i assumed that the scr's could function. i am very new to this so any guidance with a starting point would be appreciated greatly.
    thanx in advanced.
  6. Ramussons

    Active Member

    May 3, 2013
    One needs to synthesize a Sinewave by PWM techniques for what you have in mind.
    The fundamental limitation in using SCR's or Thyristors for this is that there is No Control to turn them Off. I've heard about Gate Turn Off SCR's (GTOSCR) but don't know if they ever came to commercial use.

    In Invertors, Turn Off is forced by "Commutation" by another SCR, which in turn is Commuted by the first SCR. This cycle continues.