TURN-OFF ANALYSIS OF PT AND NPT IGBTS IN ZERO-CURRENT SWITCHING

The lower turn-off losses in zero-current switching (ZCS) converters a s compared to the conventional hard switching mode using insulated gat e bipolar transistors (IGBT). depends on the intrinsic bipolar Junctio n transistor structure. Whichever the IGBT type may be, a significant part of the stored charge is removed from the base of the intrinsic bi polar junction transistor in ZCS because of the spontaneous current de crease, and because of the antiparallel diode turn-on. The turn-off lo ss reduction is especially significant when the carrier lifetime is lo w.