Active short circuit overcurrent detection

A method of operating a switching inverter circuit of an electric motor, the method comprising:

• activating, in a first operating mode, gate drive signals to insulated gate bipolar transistors (IGBTs) of the inverter circuit to provide electrical energy to the electric motor;
• activating, in an Active Short Circuit (ASC) mode, the gate drive signals to one of a top set of the IGBTs of the switching inverter circuit or a bottom set of the IGBTs of the switching inverter circuit when detecting a back electromotive force (back-EMF) failure of the electric motor;
• disabling the gate drive signals to the IGBTs of the switching inverter circuit in the first operating mode when detecting overcurrent using a first overcurrent detection threshold;
• and
• disabling the gate drive signals to the IGBTs of the switching inverter circuit in the ASC mode when detecting overcurrent using a second overcurrent detection threshold greater than the first overcurrent detection threshold.

A fault-detection circuit for a switching inverter circuit of an electric motor, the fault-detection circuit comprising:

• an overcurrent detection circuit;
• a back electromotive force (back-EMF) failure detection circuit;
• a control circuit configured to:
• disable gate drive signals produced by the switching inverter circuit in response to the overcurrent detection circuit detecting overcurrent that exceeds an overcurrent detection threshold of a first current value, wherein the gate drive signals drive insulated gate bipolar transistors (IGBTs) that provide power to the electric motor;
• and
• enable gate drive signals to activate one of a top set of IGBTs or a bottom set of IGBTs in an Active Short Circuit (ASC) mode in response to detection of a back electromotive force (back-EMF) failure and change the overcurrent detection threshold to a second overcurrent value greater than the first current value when in the ASC mode.