The design of IGCT Gate-Unit equipped in the three-level NPC converter

IGCT Gate Unit for Zero-Voltage-Switching Resonant DC Transformer Applications

“…Note that in contrast to the typical gate unit operation [12], [13], [17] where the backporch current is reduced when the gate voltage becomes negative, the backporch current is increased to 9 A in the proposed gate unit in order to accelerate the build up of the retrigger pulse. This is possible because the excessive energy during this kind of operation is not dissipated but it is recuperated into the capacitor C off .…”

“…All gate units from the literature [12]- [17] provide the following basic functions, where each is typically implemented in its own dedicated hardware stage:…”

“…This effect has been considered and studied in e.g. [12], [13], [17]. In gate units, this occurrence is usually coped with by adding an additional stage that reduces the gate current by dissipating the energy in the gate unit [12], [17].…”

“…[12], [13], [17]. In gate units, this occurrence is usually coped with by adding an additional stage that reduces the gate current by dissipating the energy in the gate unit [12], [17]. After the current of the antiparallel diode becomes lower (its voltage drop becomes lower), the PN junction near anode starts blocking and the voltage becomes positive.…”

“…In the literature, the capacitor C off is typically implemented using electrolyte aluminum capacitors [14], [17], [19] or the ceramic chip capacitors [13], [16], [19]. While the electrolyte aluminum capacitors have clear cost advantages, they are rather bulky, have high stray inductance, and allow for only low rms currents, which leads to typical high number of parallel-connected capacitors that populate large area of the gate unit.…”