longer dead time (interlock delay) between switching of T
must be observed in
order to avoid cross-currents between the transistors.
Push-pull converter in half-bridge configurationwith toroidal core
6.4.3 Under-voltage lock-out (UVLO)
The operation of an IGBT with insufficient gate voltage is to be avoided due to the
increased conduction losses of the power semiconductor. The lower the gate voltage,
the higher the collector-emitter voltage of the IGBT at a given current. Assuming a
constant current during the conducting phase of the IGBT then the following equation
canbe used for the resulting conduction losses:
This is also explained by the output characteristic of an IGBT.
IGBToutput characteristic (300A/1.2kV IGBT)
Once the current changes, the relationship is more complicated (chapter
, but in
principle still validand sufficient for further consideration.