On Sep 19, 11:57*am, Grumpy The Mule wrote:
This is one advantage of the flyback and asymmetrical forward
converters. *They will reset if there's enough dead time.
So in those cases your ROM circuit would do the trick.

Symmetrical topologies like push-pull, half-bridge and
full-bridge can saturate even if there is plenty of dead
time. * The core is always being driven by the control
circuit, so it has no time to relax, *If the drive isn't
equal and opposite for each half cycle there is an offset
which the core accumulates. *Eventually it will saturate.
unless there is some means to compensate for the imbalance
of the drive (like a coupling capacitor.)
So here the ROM circuit will not help.

wrote in news:8e344554-a8d0-4796-ae20-
:



I work with a couple of pieces of equipment that synthesises a
repetitive waveform by playing back the waeform from a ROM. I thought
I could do something like this to control the on-off timing of the
IGBT. This would set a minimum time between turn on and turn off and
the rest would be controlled by PWM.- Hide quoted text -

- Show quoted text -

I think I get it. Would this explain why in a push-pull topology after
the transistors have been replaced a couple of times the power supply
just keeps failing for no apparent reason?

Are you saying that in other topologies it doesnt saturate or that it
doesnt matter if it does?

Ordered Abe's book.

Jimmie