Active short circuit fault strategy with external controller

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

• monitoring for faults of the inverter circuit using an Active Short Circuit (ASC) Fault circuit;
• detecting an overvoltage fault using the ASC Fault circuit;
• determining whether a rotor speed of the electric motor is greater than a specified threshold speed using an external controller external to the inverter circuit;
• and
• activating a default set of one of top insulated gate bipolar transistor (IGBTs) or bottom IGBTs when the overvoltage fault is present and the rotor speed of the electric motor is less than the threshold speed.

A fault-detection circuit for an electric motor, the fault-detection circuit comprising:

• an external controller including a top insulated gate bipolar transistor (IGBT) control signal output and a bottom IGBT control signal output for IGBT devices of a switching inverter circuit, and configured to activate one of the top IGBT control signal output or the bottom IGBT control signal output in response to detecting rotor speed of the electric motor that exceeds a specified threshold speed;
• and
• an Active Short Circuit (ASC) Fault circuit configured to:
• determine an overvoltage fault for the switching inverter circuit;
• determine when rotor speed of the electric motor exceeds a specified threshold speed;
• and
• activate a default one of a set of top IGBTs or a set of bottom IGBTs when the overvoltage fault is present and the rotor speed is less than the specified threshold speed.