IGBTs and Schottky diodes in high power frequency applications

This paper presents transistor measurements made on an inverter with series resonant load, where the switching frequency varies slightly above the resonant frequency (inductive mode) and below the resonant frequency (capacitive mode). The conditions under capacitive mode is of special interest because the reverse current prior to turn off may reduce the IGBT's stored charge and thereby reduce the switching losses. In this paper we investigate the effect this reverse current has on both the IGBT's stored charge and switching losses. In the test circuit, the free wheeling diodes are realized through series connections of Schottky diodes.