Semiconductor protection device and power converting system

摘要

A semiconductor protection device is used to suppress a surge voltage to a preset value or less, the surge voltage being caused at each turn-OFF time of 50 Hz to 20 kHz of a main IGBT functioning as a switch of a power converting system. The semiconductor protection device includes a protection IGBT for forming a bypass connected in parallel with the main IGBT and an electric field sensing element connected in a reverse direction between the collector of the main IGBT and the gate of the protection IGBT. When the surge voltage exceeds a preset value which is a breakdown voltage of the electric field sensing element, the protection IGBT is turned ON so as to cause a current generated by energy of the surge voltage to be bypassed.