BI-DIRECTIONAL MOSFET COOLING FOR AN ELECTRIC MACHINE

• US 20160105080A1
• Filed: 10/07/2015
• Published: 04/14/2016
• Est. Priority Date: 10/08/2014
• Status: Active Grant

• Current Assignee: BorgWarner Incorporated
• Original Assignee: Remy Technologies LLC (BorgWarner Incorporated)
• Inventors: Bradfield, Michael D.
• Granted Patent: US 10,164,504 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 2213/12 Machines characterised by the modularity of some components
• CPC Class Codes: H02K 5/18 with ribs or fins for improving heat transfer
• CPC Class Codes: H02K 9/02 by ambient air flowing through the machine
• CPC Class Codes: H02K 9/06 with fans or impellers driven by the machine shaft
• CPC Class Codes: H02K 9/227 Heat sinks
• CPC Class Codes: H05K 7/20127 Natural convection
• CPC Class Codes: H05K 7/20409 Outer radiating structures on heat dissipating housings, e.g. fins integrated with the housing
• CPC Class Codes: H05K 7/209 Heat transfer by conduction from internal heat source to heat radiating structure H05K7/20909 takes precedence
• CPC Class Codes: H05K 7/20918 the components being isolated from air flow, e.g. hollow heat sinks, wind tunnels or funnels

Abstract

A power module for an electric machine. The power module includes a thermally conductive base having opposite first and second surfaces. The first surface is adapted for mounting the power module in conductive thermal communication with a heat sink. A MOSFET superposes the base second surface and is in conductive thermal communication with the base. A MOSFET driver superposes the base second surface and is operatively connected to the MOSFET. The transference from the power module of heat generated by the MOSFET and the MOSFET driver from the power module is directed along a primary cooling path to the heat sink through the base and a secondary cooling path to ambient air. The primary and secondary cooling paths are separate from each other. An electronics package and an electric machine including a power module are also disclosed.

Claims

1. A power module for an electric machine comprising:

a thermally conductive base having opposite first and second surfaces, the first surface adapted for mounting the power module in conductive thermal communication with a heat sink;

a MOSFET superposing the base second surface and in conductive thermal communication with the base; and

a MOSFET driver superposing the base second surface and operatively connected to the MOSFET;

wherein the transference from the power module of heat generated by the MOSFET and the MOSFET driver from the power module is directed along a primary cooling path to the heat sink through the base and a secondary cooling path to ambient air, and the primary and secondary cooling paths are separate from each other.

2. The power module of claim 1, wherein the MOSFET driver is in conductive thermal communication with the base second surface, and transference at least some of the heat generated by the MOSFET driver is directed along the primary cooling path.

3. The power module of claim 1, further comprising a thermally conductive cover plate having an interior surface superposing the base second surface and an exterior surface exposed to ambient air, wherein heat transference directed along the secondary path is through the cover plate.

4. The power module of claim 3, wherein the cover plate is provided with a thermally conductive boss extending from the cover plate interior surface into spaced proximity with the MOSFET driver, and heat transference along the secondary cooling path includes thermal conduction through the boss.

5. The power module of claim 3, wherein the cover plate is provided with a plurality of thermally conductive bosses extending from the cover plate interior surface into respective spaced proximity with one of the MOSFET and the MOSFET driver, and heat transference along the secondary cooling path includes thermal conduction through the plurality of bosses.

6. The power module of claim 3, wherein the cover plate exterior surface defines a plurality of fins, and heat transference along the secondary cooling path includes thermal convection from the fins to ambient air.

7. An electronic package adapted for connection to a rear frame member of an electric machine, the electronic package comprising:

a cooling tower having opposite first and second axial ends spaced along a package central axis, the cooling tower comprising a metallic wall extending about the package central axis to define a radially outer wall surface; and

a plurality of power modules according to claim 1 mounted in conductive thermal communication to the cooling tower at circumferentially distributed positions on the radially outer wall surface;

wherein the cooling tower defines a heat sink to which heat transference from each power module occurs along the respective primary cooling path.

8. The electronic package of claim 7, wherein heat transference from the plurality of power modules collectively occurs, relative to the package central axis, along the respective primary cooling paths and along the respective secondary cooling paths.

9. The electronic package of claim 7, wherein the metallic wall of the cooling tower defines a radially inner wall surface, the radially inner wall surface defining an axially extending air passage through the cooling tower, the air passage having an inlet proximate the first axial end, and the cooling tower comprises a plurality of spaced metallic ribs in conductive thermal communication with the radially inner wall surface, the ribs traversing the air passage.

10. The electronic package of claim 7, wherein each power module respectively comprises a thermally conductive cover plate having an interior surface superposing the base second surface and an exterior surface exposed to ambient air, wherein heat transference directed along the secondary path is through the cover plate.

11. The electronic package of claim 10, wherein respective to each power module the cover plate is provided with a thermally conductive boss extending from the cover plate interior surface into spaced proximity with the MOSFET driver, and heat transference along the secondary cooling path includes thermal conduction through the boss.

12. The electronic package of claim 10, wherein respective to each power module the cover plate is provided with a plurality of thermally conductive bosses extending from the cover plate interior surface into respective spaced proximity with one of the MOSFET and the MOSFET driver, and heat transference along the secondary cooling path includes thermal conduction through the plurality of bosses.

13. The electronic package of claim 10, wherein respective to each power module the cover plate exterior surface defines a plurality of fins, and heat transference along the secondary cooling path includes thermal convection from the fins to ambient air.

14. An electric machine comprising a stator defining a machine central axis, a rotor surrounded by and rotatable relative to the stator about the machine central axis, a rear frame member rotatably fixed relative to the stator and through which the machine central axis extends, and an electronic package according to claim 7,

wherein the machine central axis extends through the electronic package and the cooling tower is connected to the rear frame member.

15. The electric machine of claim 14, wherein the machine central axis and the package central axis coincide.

16. An electric machine comprising a stator defining a machine central axis, a rotor surrounded by and rotatable relative to the stator about the machine central axis, a rear frame member rotatably fixed relative to the stator and through which the machine central axis extends, and an electronic package according to claim 7;

wherein the metallic wall of the cooling tower defines a radially inner wall surface, the radially inner wall surface defining an axially extending air passage through the cooling tower, the air passage having an inlet proximate the first axial end, and the cooling tower comprises a plurality of spaced metallic ribs in conductive thermal communication with the radially inner wall surface, the ribs traversing the air passage; and

wherein the machine central axis extends through the electronic package and the cooling tower is connected to the rear frame member.

17. The electric machine of claim 16, wherein the machine central axis and the package central axis coincide.

18. The electric machine of claim 16, wherein the electric machine is air-cooled and the rear frame member has an aperture through which cooling air flow is drawn generally axially, in the direction of the rotor relative to the electronic package, for cooling the electric machine at locations downstream of the aperture,

wherein the air passage has an outlet proximate the second axial end, and the air passage outlet is in fluid communication with the rear frame member aperture, and

wherein cooling air flow is drawn into the air passage inlet and through the air passage, convective heat transfer along the primary cooling path occurs between the cooling tower wall and ribs and the cooling air flow along the air passage, and the cooling air flow proceeds through the air passage outlet and the rear frame member aperture for cooling the electric machine at locations downstream of the aperture.

19. The electric machine of claim 18, further comprising a fan rotatable with the rotor about the machine central axis, wherein the air flow through the aperture is induced by fan rotation.

20. The electric machine of claim 16,

wherein the electric machine is liquid-cooled and the rear frame member defines a metallic wall extending substantially perpendicularly relative to the machine central axis, the rear frame member wall having an inner axial side in contact with liquid coolant and an opposite outer axial side in conductive thermal communication with the cooling tower, and

wherein conductive heat transfer occurs between the cooling tower and the rear frame member wall, and convective heat transfer occurs between the rear frame member wall and the liquid coolant.

21. The electric machine of claim 14, wherein each power module respectively comprises a thermally conductive cover plate having an interior surface superposing the base second surface and an exterior surface exposed to ambient air, wherein heat transference directed along the secondary path is through the cover plate.

22. The electric machine of claim 21, wherein respective to each power module the cover plate is provided with a thermally conductive boss extending from the cover plate interior surface into spaced proximity with the MOSFET driver, and heat transference along the secondary cooling path includes thermal conduction through the boss.

23. The electric machine of claim 21, wherein respective to each power module the cover plate is provided with a plurality of thermally conductive bosses extending from the cover plate interior surface into respective spaced proximity with one of the MOSFET and the MOSFET driver, and heat transference along the secondary cooling path includes thermal conduction through the plurality of bosses.

24. The electric machine of claim 21, wherein respective to each power module the cover plate exterior surface defines a plurality of fins, and heat transference along the second cooling path includes thermal convection from the fins to ambient air.