Re: SSTC dead times

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: sstaylor-at-uiuc.edu 

A good way to test the dead time is to run the bridge with a
resistive load, and put a resistor in series with the supply
to the bridge.  Use a relatively low voltage (~12V) supply for
these tests.

Use a scope and measure the voltage across the
supply resistor.  If there are spaces where the voltage drops,
but the drive signal is still high (or low, whichever side of
the half bridge you're looking at) the deadtime is too long
(current flow stops).

If, on the other hand, the voltage across the resistor spikes,
there is shoot through, and the dead time needs to be
increased.

This is a pretty good test, but because of the exponential
decay behavior of the turn on/off times, it will be hard to
get perfect waverforms.  As well, the waveforms will change
with applied input voltage, as the effective gate capacitance
will change, and the gate waveform will change.

Sean Taylor
Urbana, IL