Rotary electric machine with stator assembly having stator slots lined with multiple molding materials

A method for insulating a stator assembly for a rotary electric machine, comprising:

• inserting a first molding tool into a stator slot of a stator core of the stator assembly to thereby define a first void volume between the first molding tool and tooth walls of an adjacent pair of stator teeth of the stator core;
• filling the first void volume with a dielectric molding compound;
• curing the dielectric molding compound to form a slot liner layer adjacent to the tooth walls;
• removing the first molding tool from the stator slot to form a second void volume within the stator slot;
• inserting conductive stator windings into the second void volume;
• filling the second void volume with a thermally-conductive molding compound;
• and
• curing the thermally-conductive molding compound to form a slot fill layer surrounding the conductive stator windings.

An electrical system comprising:

• a power inverter module connectable to a direct current (DC) voltage bus, and operable for outputting an alternating current (AC) output voltage in response to a DC input voltage;
• an AC voltage bus connected to the power inverter module;
• and
• a rotary electric machine connected to the AC voltage bus, the rotary electric machine having a rotor assembly surrounded by a stator assembly, the stator assembly comprising:
• a stator yoke defining a center opening, and having a longitudinal center axis, an outer diameter surface, and an inner diameter surface;
• a plurality of stator teeth connected to the stator yoke to form a stator core, the stator teeth projecting radially into the center opening toward the longitudinal center axis and collectively defining a plurality of stator slots, wherein the stator slots extend radially from the inner diameter surface toward the outer diameter surface of the stator yoke;
• conductive stator windings disposed within the stator slots;
• and
• a molding material disposed within and substantially filling the stator slots around the stator windings, and providing a predetermined thermoelectrical performance level at different regions of the stator slots, including two or more of electrical insulation level, a thermal conductivity level, or an electrostatic shielding level, wherein the molding material includes a slot liner layer adjacent to and in contact with a stator wall of the stator teeth, the slot liner layer being constructed of a dielectric molding compound having a dielectric strength of at least about 20 kV/mm, and a slot fill layer surrounding the stator windings, wherein the slot fill layer is constructed of a thermally-conductive molding compound having a thermal conductivity of at least about 1 W/mK.