H Bridge shoot through protection

Discussion in 'The Projects Forum' started by davidhills, Dec 20, 2013.

  1. davidhills

    Thread Starter Member

    Sep 14, 2008
    Good Morning All

    I am building a +/- 63volt square wave invertor for AC Tig welding from a high current DC 63volt supply.

    I am using 4 x 100amp thyristor in an H Bridge, capacitively commutated by 4 mosfets.

    Driving a Purely restrictive load.(I think arc is Purely restrictive)

    I want to add some simple shoot through protection for the thyristors

    Any ideas or options?

    thanks David
  2. SgtWookie


    Jul 17, 2007
    I'm curious as to how you plan on getting the thyristors to turn OFF once you have them turned ON?

    Thyristors are really for use with switching AC, as they turn off automatically when the current flow through them drops below their threshold current. Since your supply is DC, you'll have to wait to switch polarities until the welder breaks the arc.
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
    I think (from being a tig weldor) that his out put is AC. It is just a square wave instead of a sine wave. Quote the OP, "I am building a +/- 63volt square wave invertor".

    Most tig welders use thyristors in them to do this.