PWM chip that can drive an H bridge?

[Ignoramus30105]

Shoot-through connects the two power supply rails together, leading to
high currents in the switches and some rather dramatic behavior (wear
safety goggles).

Catch diodes would probably be more appropriate, and are routine in this
sort of application.

I think that my IGBT's already have catch diodes (formed like a bridge
also). Toshiba-MG200Q2YS40.

See file Toshiba-MG200Q2YS40_DAT-IGBT.pdf

i
--

 

[Spehro Pefhany]

Catch diodes would probably be more appropriate, and are routine in this
sort of application.

If I read the app note correctly, the input to the output inverter is
assumed to have significant series inductance. In this situation,
catch diodes are not necessarily helpful.


Best regards,
Spehro Pefhany

 

[Chris Jones]

Yes, because the supply is inductive. If the IGBT bridge were to
switch off altogether (as in any "normal" PWM design), there
would be IGBT bits all over the place.

robert

That will happen anyway when the electrode gets lifted too far from the
metal and the arc goes out. But the OP is going to put varistors across
the supply, I hope.
Chris

 

[Don Foreman]

Is there a PWM chip that can properly drive an H bridge? (with dead
time, fast on and off times etc)?

thanks

i

You might find something at
http://www.allegromicro.com/