The invention discloses an IGBT drive protection circuit, which comprises positive and
negative power supplies, a
signal and feedback
optical coupler, a
signal amplification circuit, an undervoltage detection and indication circuit, an IGBT
overcurrent detection and reset circuit, a soft turn-off circuit, a fault latch and retaining circuit and the like. The undervoltage detection circuit if the power supply at the receiving terminal of the
signal optical coupler and the positive /
negative power supply are undervoltage, and an LED is lighted if the power supply at the receiving terminal of thesignal
optical coupler and the positive /
negative power supply are not undervoltage to enable a drive circuit. The IGBT
overcurrent detection circuit can sample a collector-emitter
voltage drop duringthe period when the IGBT is turned on, detect time
delay according to high-low dynamic adjustment of the collector-emitter
voltage drop, start a soft turn-off process and perform
self locking to ensure soft turn off when the collector-emitter
voltage drop exceeds a preset threshold, retain the
overcurrent fault state, keep the IGBT turned off during the retaining period, transmit the state to a
control circuit and keep time set between
millisecond and second.