# US 2023/0054794 A1 · Rotary electric machine with stator assembly having stator slots lined with multiple molding materials > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0054794 A1 - Document ID: US20230054794A1 - Status: Published application - Kind: A1 - Application number: 17/405,480 - Filed: 2021-08-18 - Published: 2023-02-23 - Earliest claimed: 2021-08-18 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: Alireza Fatemi; Anthony M. Coppola; Farzad Samie; Thomas W. Nehl - Web page: https://patentgrep.com/patent/US20230054794A1 ## CPC - H02K 3/24: with channels or ducts for cooling medium between the conductors - H02K 1/165: {Shape, form or location of the slots} - H02K 1/20: with channels or ducts for flow of cooling medium - H02K 3/12: arranged in slots - H02K 3/28: Layout of windings or of connections between windings (windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32) - H02K 3/30: Windings characterised by the insulating material - H02K 3/345: {between conductor and core, e.g. slot insulation} - H02K 15/105: {to the windings} - H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A stator assembly for an electric machine includes stator teeth connected to a stator yoke to form a stator core. Adjacent teeth define a stator slot. Stator windings are disposed within the slot. A molding material fills the slot around the windings, providing a desired thermoelectrical performance level at different slot regions, including electrical insulation, thermal conductivity, and/or electrostatic shielding levels. A method insulates the stator assembly by inserting a molding tool(s) into the slot to define a void volume, filling the void volume with the dielectric molding material, and curing the dielectric molding material to form a slot liner layer adjacent to the tooth walls. A slot opening between adjacent teeth is filled with an electrically-conductive resin to form an electrostatic shielding layer. An electrical system includes an AC voltage bus connected to a power inverter module and to the electric machine having the above-described stator assembly. ## Claims ### Claim 1 A 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 in conjunction therewith, 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 of the stator core yoke toward the outer diameter surface of the stator core yoke; conductive stator windings disposed within the stator slots; and a molding material disposed within and substantially filling a volume of the stator slots around the stator windings, and providing a predetermined thermoelectrical performance level in different regions of the stator slots, including two or more of an electrical insulation level, a thermal conductivity level, or an electrostatic shielding level. ### Claim 2 (depends on 1) The stator assembly of claim 1, wherein the molding material includes a slot liner layer and a slot fill layer, the slot liner layer being adjacent to and in contact with a stator wall of the stator teeth, and constructed of a dielectric molding compound, and the slot fill layer surrounding the stator windings and constructed of a thermally-conductive molding compound. ### Claim 3 (depends on 2) The stator assembly of claim 2, wherein the dielectric molding compound of the slot liner layer is constructed of a first thermosetting polymer material having a dielectric strength of at least about 20 kV/mm, and the thermally-conductive molding compound of the slot fill layer is constructed of a second thermosetting polymer material containing thermally-conductive particles and/or fiber fill materials. ### Claim 4 (depends on 3) The stator assembly of claim 3, wherein the dielectric molding compound of the slot liner layer has a thermal conductivity of about 0.75 W/mK to about 10 W/mK, and the slot fill layer has a thermal conductivity of at least about 1 W /mK. ### Claim 5 (depends on 2) The stator assembly of claim 2, wherein each adjacent pair of the stator teeth is separated by a respective slot opening, and the molding material includes an electrostatic shielding layer disposed within the respective slot opening and constructed of an electrically-conductive material. ### Claim 6 (depends on 2) The stator assembly of claim 2, wherein the stator assembly is characterized by an absence of stator slot openings between each adjacent pair of the stator teeth, such that the stator slots are closed. ### Claim 7 (depends on 1) The stator assembly of claim 1, wherein the stator assembly includes an electrically-insulating paper liner positioned adjacent to the stator teeth within each respective one of the stator slots. ### Claim 8 (depends on 1) The stator assembly of claim 1, further comprising dielectric spacers disposed between the stator windings and the stator yoke. ### Claim 9 (depends on 1) The stator assembly of claim 1, further comprising coolant channels disposed within one or more of the stator slots, wherein the coolant channels are configured to connect to a supply of a heat transfer fluid. ### Claim 10 (depends on 1) The stator assembly of claim 1, wherein the molding material includes a dielectric molding compound, a thermally-conductive molding compound, and an electrically-conductive resin material, the dielectric molding compound being arranged between tooth walls of the adjacent stator teeth and the thermally-conductive molding compound, the thermally-conductive molding compound being arranged between the dielectric molding compound and the stator windings, and the electrically-conductive resin material being arranged in a slot opening defined between an adjacent pairs of the stator teeth. ### Claim 11 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. ### Claim 12 (depends on 11) The method of claim 11, further comprising: filling a slot opening between the adjacent pair of stator teeth with an electrically-conductive resin; and curing the electrically-conductive resin to form an electrostatic shielding layer. ### Claim 13 (depends on 12) The method of claim 12, further comprising: inserting a second molding tool into the slot opening before filling the first void volume with the dielectric molding compound; and removing the second molding tool from the slot opening after curing the dielectric molding compound and before filling the slot opening with the electrically-conductive resin. ### Claim 14 (depends on 11) The method of claim 11, wherein the dielectric molding compound includes a thermosetting polymer material having a dielectric strength of at least about 20 kV/mm. ### Claim 15 (depends on 14) The method of claim 14, wherein the dielectric molding compound has a thermal conductivity of about 0.75 W/mK to about 10 W/mK. ### Claim 16 (depends on 11) The method of claim 11, wherein the thermally-conductive molding compound includes a thermosetting polymer material having a thermal conductivity of at least about 1/mK, and containing conductive particle and/or fiber fill materials. ### Claim 17 (depends on 11) The method of claim 11, further comprising forming at least one coolant channel within the stator slot, wherein the at least one coolant channel is configured to connect to a supply of a heat transfer fluid. ### Claim 18 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. ### Claim 19 (depends on 18) The electrical system of claim 18, wherein each adjacent pair of the stator teeth is separated by a slot opening, and the molding material includes an electrostatic shielding layer disposed within the slot opening and constructed of an electrically-conductive material. ### Claim 20 (depends on 18) The electrical system of claim 18, wherein the electrical system is part of an electrified vehicle, and wherein the rotary electric machine is a propulsion motor for the electrified vehicle.