Bearing current mitigation for an electric machine embedded in a gas turbine engine

A method, comprising:

• operating a propulsor having a gas turbine engine equipped with an electric machine operatively coupled with a shaft of the gas turbine engine, the electric machine being electrically coupled with a power converter, and a rotor hub comprising a hub flange and being operatively coupled to the shaft;
• and
• wherein operating the propulsor comprises:
• i) interrupting, via an insulated joint that operatively couples a rotor assembly of the electric machine with the shaft, a common mode electric current driven by the power converter to the electric machine from flowing between the rotor assembly and the shaft, the insulated joint comprising a plurality of insulative layers, at least one of the plurality of insulative layers extending between the hub flange and a connection flange of the rotor assembly, wherein the plurality of insulative layers comprise hub-side insulative layers, wherein the hub-side insulative layers comprise an outer layer and an inner layer spaced apart along an axial direction;
• and
• ii) electrically grounding, by a grounding device, the shaft.

A propulsor, comprising:

• a gas turbine engine having a shaft and one or more bearings supporting the shaft;
• a rotor hub operatively coupled to the shaft and comprising a hub flange;
• an electric machine comprising a stator assembly and a rotor assembly;
• a rotor connection member operatively coupled to the rotor assembly of the electric machine and comprising a connection flange;
• and
• an insulated joint for operatively coupling the rotor assembly with the shaft, the insulating joint comprising:
• a plurality of insulative layers, at least one of the plurality of insulative layers extending between the hub flange and the connection flange to interrupt common mode electric current from flowing between the rotor assembly and the shaft, wherein the plurality of insulative layers comprise interface-side insulative layers, wherein the interface-side insulative layers comprise an outer layer and an inner layer spaced apart along an axial direction.