Electric machine stator cooling systems and methods
An electromagnet for an electric machine having a stack of laminations defining a tooth and a yoke segment, and an insulating bobbin surrounding a portion of the tooth of each lamination, such that each lamination is held against adjacent laminations by the bobbin. The disclosed electromagnets also have electrically conductive windings surrounding a portion of the bobbin; and an encapsulant fully encapsulating the bobbin and windings, wherein the encapsulant comprises a dielectric material and an additive to increase the thermal conductivity of the encapsulant.
1. An electromagnet for an electric machine comprising:
a stack of laminations, with each lamination defining a tooth and a yoke segment;
an insulating bobbin surrounding a portion of the tooth of each lamination,
wherein each lamination is held against adjacent laminations by the bobbin;
electrically conductive windings surrounding a portion of the bobbin; and
an encapsulant fully encapsulating the bobbin and windings; and wherein the stack of individual laminations comprises;
a first lamination;
a second lamination adjacent to the first lamination;
a first heat transfer layer bonded to a first planar face of the first lamination; and
a second heat transfer layer bonded to a first planar face of the second lamination.
2. The electromagnet of claim 1 wherein the encapsulant comprises a dielectric material and an additive to increase the thermal conductivity of the encapsulant.
3. The electromagnet of claim 2 wherein the dielectric material comprises a polymer and the additive comprises one or more of boron nitride, silicon carbide, silicon; aluminum powder, copper powder, metal oxide, ceramic, and graphene.
4. The electromagnet of claim 1 wherein the first lamination and the second lamination each further comprises a dielectric layer in physical contact with a second planar face, opposite the heat transfer layer.
5. The electromagnet of claim 1 wherein the yoke segment defines a tongue structure at a first outside edge and wherein the yoke segment defines a groove structure at a second outside edge, opposite the first outside edge.
6. A method of fabricating an electromagnet for an electric machine comprising:
providing a stack of laminations defining a tooth and a yoke segment;
placing an insulating bobbin around a portion of the tooth of each lamination, to hold each lamination against adjacent laminations with the bobbin;
winding an electrically conductive winding around a portion of the bobbin;
fully encapsulating the bobbin and windings, wherein the encapsulant comprises a dielectric material and an additive to increase the thermal conductivity of the encapsulant;
providing first and second individual laminations that are adjacent to each other; and
bonding a heat transfer layer to a first planar face of each of the first and second individual laminations.
7. The method of claim 6 wherein the dielectric material comprises a polymer and the additive comprises one or more of boron nitride, silicon carbide, silicon; aluminum powder, copper powder, metal oxide, ceramic, and graphene.
8. The method of claim 6 further comprising providing each of the first and second laminations with a dielectric layer in physical contact with a second planar face, opposite the heat transfer layer.
9. The method of claim 6 further comprising providing the yoke segment with a tongue structure at a first outside edge.
10. The method of claim 9 further comprising providing the yoke segment with a groove structure at a second outside edge, opposite the first outside edge.