PERMANENT MAGNET (PM) ELECTRIC MACHINE INCLUDING PERMANENT MAGNETS PROVIDED WITH A THERMAL INTERFACE MATERIAL (TIM) BETWEEN ADJACENT PERMANENT MAGNETS

1 . A permanent magnet electric machine comprising:

a housing;

a stator mounted within the housing; and

a rotor assembly rotatably mounted within the housing relative to the stator, the rotor assembly including a rotor body having plurality of rotor laminations, a plurality of permanent magnets having axial end portions mounted to the rotor body, and an amount of thermal interface material (TIM) arranged between the axial end portions of adjacent ones of the plurality of permanent magnets.

2 . The permanent magnet electric machine according to claim 2 , wherein the rotor body extends from a first end portion to a second end portion, a heat sink ring is mounted to one of the first end portion and the second end portion.

3 . The permanent magnet electric machine according to claim 2 , wherein the heat sink ring includes an outer surface and a substantially planar inner surface arranged in thermal communication with an outer axial end portion of one of the plurality of permanent magnets.

4 . The permanent magnet electric machine according to claim 3 , further comprising: an amount of thermal interface material between the substantially planar inner surface of the heat sink ring and the outer axial end portion of the one of the plurality of permanent magnets.

5 . The permanent magnet electric machine according to claim 3 , wherein the outer surface of the heat sink ring includes a substantially planar profile.

6 . The permanent magnet electric machine according to claim 2 , wherein the heat sink ring is formed from a thermally conductive material.

7 . The permanent magnet electric machine according to claim 1 , wherein each of the plurality of laminations includes a plurality of slots, at least one of the plurality of permanent magnets being arranged in one of the plurality of slots of one or more of the plurality of laminations.

8 . A rotor assembly comprising:

a rotor body having plurality of rotor laminations;

a plurality of permanent magnets having axial end portions mounted relative to the rotor body; and

an amount of thermal interface material (TIM) arranged between the axial end portions of adjacent ones of the plurality of permanent magnets.

9 . The rotor assembly according to claim 8 , wherein the rotor body includes a first end portion and a second end portion, a heat sink ring is mounted to one of the first end portion and the second end portion.

10 . The rotor assembly according to claim 9 , wherein the heat sink ring includes an outer surface and a substantially planar inner surface arranged in thermal communication with an outer axial end portion of one of the plurality of permanent magnets.

11 . The rotor assembly according to claim 10 , further comprising: an amount of TIM between the substantially planar inner surface of the heat sink ring and the outer axial end portion of the one of the plurality of permanent magnets.

12 . The rotor assembly according to claim 10 , wherein the outer surface of the heat sink ring includes a substantially planar profile.

13 . The rotor assembly according to claim 9 , wherein the heat sink ring is formed from a thermally conductive material.

14 . The rotor assembly according to claim 9 , wherein each of the plurality of laminations includes a plurality of slots, at least one of the plurality of permanent magnets being arranged in one of the plurality of slots of one or more of the plurality of laminations.

15 . A method of forming a rotor assembly for an electric machine, the method comprising:

stacking a plurality of rotor laminations;

joining the plurality of rotor laminations to form a rotor body;

mounting a first permanent magnet having a first axial end portion to the rotor body;

positioning a thermal interface material (TIM) at the first axial end portion;

mounting a second permanent magnet having a second axial end portion to the rotor body; and

positioning the second axial end portion of the second permanent magnet into thermal contact with the first end portion of the first permanent magnet through the TIM.

16 . The method of claim 15 further comprising: positioning a heat sink ring on an end portion of the rotor body.

17 . The method of claim 16 , further comprising: positioning a TIM between an outer axial end portion of the first magnet and an inner surface of the heat sink ring.

18 . The method of claim 16 , further comprising: positioning another heat sink ring on another end portion of the rotor body.

19 . The method of claim 18 , further comprising: positioning another TIM between an outer axial end portion of the second permanent magnet and an inner surface of the another heat sink ring.

20 . The method of claim 15 , further comprising:

aligning a plurality of slots on each of the plurality of laminations; and

inserting the first and second permanent magnets into one of the plurality of slots of one or more of the plurality of laminations.