Turn-off analysis of PT and NPT IGBTs in zero-current switching

The lower turn-off losses in zero-current switching (ZCS) converters as compared to the conventional hard switching mode using insulated gate bipolar transistors (IGBT), depends on the intrinsic bipolar junction transistor structure. Whichever the IGBT type may be, a significant part of the stored charge is removed from the base of the intrinsic bipolar junction transistor in ZCS because of the spontaneous current decrease, and because of the antiparallel diode turn-on. The turn-off loss reduction is especially significant when the carrier lifetime is low