Investigation of gate voltage oscillations in an IGBT module under short circuit conditions

The gate voltage oscillations in IGBT modules under short circuit conditions were investigated. In IGBT modules containing two chips in parallel, the amplitudes of the gate voltage oscillations were considerably larger than those in modules with single chip configurations. To investigate the gate voltage oscillations, a small signal analysis was performed on parallel circuits containing two IGBT chips. The gate voltage oscillations in parallel chips configurations could be described by a feedback amplifier model. The results of this analysis showed that a high resistive impedance between the gates of the two chips in parallel and a low inductance between their emitters were effective in suppressing the gate voltage oscillations. These effects were confirmed by experiments.