A unit comprises an IGBT (insulated gate bipolar transistor), a gate drive rand a short circuit protection circuit. The gate driver is used for providing a gate of the IGBT with power voltage. The short circuit protection circuit comprises a short circuit detector and a power voltage regulator; the short circuit detector is used for judging whether or not the IGBT short circuits; the power voltage regulator is used for regulating the power voltage when the short circuit detector determines that the IGBT short circuits.