/diy/ - Do It Yourself

>>1373206

Has anyone built a high current H bridge before? I am wanting to add AC functionality(literally switched polarity square wave) to my welder which is an DC inverter design. Would MOSFETs be suitable to use as a second stage inverter?

Obvious modifications would be:
>move HF igniter down the line and add protection diodes across input
>implement a simple circuit to switch the bridge at 100Hz for AC and toggle between polarities for DC+/- modes

What annoys me is i can't find any existing implementations, they either use insanely expensive IGBT modules(200A full bridge is $600+) or don't document how the second stage works at all.

My main concerns are:
>OCV being 80v is close to 100V breakdown voltage(would a spike wreck my shit?)
>surge current is likely to be ~1kA, and since the fets are right on the output they are going to get the full force every time welding starts
>heat dissipation is going to be significant if i want to save costs and use few devices