A New Soft Self-Clamping Scheme for Improving the Self-Clamped Inductive Switching (SCIS) Capability of Automotive Ignition IGBT

The improvement of self-clamped inductive switching (SCIS) capability of ignition IGBT widely used in automotive coil driver ensures the protection of the ignition IGBT from a severe thermal stress under the abnormal switching condition such as the open secondary. We have proposed and verified a new self-clamping scheme for improving the self-clamped inductive switching (SCIS) capability of ignition IGBT by employing the collector coupled turn-on of IGBT. The proposed self-clamped IGBT has an additional power MOSFET connected between the gate and collector of main IGBT with a large gate resistance. The additional power MOSFET is turned-on temporarily at the beginning of the self-clamping mode, which increases the collector voltage of main IGBT gradually so that the proposed self-clamped IGBT reduces the hard switching energy loss, which results in improvement of the SCIS capability of main IGBT.