INDUCTOR COOLING

Abstract

An inductor is proposed that comprises: a magnetic inner core, a coil wound around the inner core, and a heat conductor arranged within the inner core and accessible from outside the inner core and the coil for conducting heat from the inner core to outside the inner core. The inner core is of a first material having a first thermal conductivity and the heat conductor is of a second material having a second thermal conductivity that is greater than the first heat conductivity.

Claims

1. An inductor comprising: a magnetic inner core; a coil having an electrical conductor wound around the inner core, wherein the electrical conductor is embedded in a carrier structure; and a heat conductor arranged within the inner core and accessible from outside the inner core and the coil for conducting heat from the inner core to outside the inner core, wherein the inner core is of a first material having a first thermal conductivity, and the heat conductor is of a second material having a second thermal conductivity that is greater than the first thermal conductivity.

2. The inductor according to claim 1, wherein the first material is a solid metal-powder compound.

3. The inductor according to claim 1, wherein the thermal conductivity of the second material is at least three times greater than the thermal conductivity of the first material.

4. The inductor according to claim 1, wherein the heat conductor extends through the inner core and is accessible from outside the inner core on opposite sides of the inner core.

5. The inductor according to claim 1, wherein the inner core has a cylindrical geometry defining a central axis, and the heat conductor is located at the central axis.

6. The inductor according to claim 1, wherein the inductor further comprises: a magnetic outer core extending on the outside of the coil and connecting to the inner core, wherein the outer core is of the same material as the inner core, and the inner core and the outer core jointly form a monolithic structure.

7. The inductor according to claim 1, wherein the inductor further comprises: a heatsink coupled to the heat conductor and configured to receive heat from the heat conductor.

8. The inductor according to claim 7, wherein the heatsink comprises: a cover and a first heat-transfer plate coupled to the heat conductor and interconnecting the heat conductor and the cover for conducting heat from the heat conductor to the cover, and the cover comprises heat dissipating fins.

9. The inductor according to claim 8, wherein the cover encircles the outer core and form a cavity in which the outer core is positioned, the cover has a first opening to the cavity and the heat conductor is coupled to the first heat-transfer plate at the first opening.

10. The inductor according to claim 8, wherein the cover comprises: a side panel; wherein the first heat-transfer plate interconnects the heat conductor and the side panel for conducting heat from the heat conductor to the side panel.

11. The inductor according to claim 1, wherein the carrier structure is a cured epoxy resin.

12. A method for manufacturing an inductor comprising a coil and a heat conductor, the coil having an electrical conductor embedded in a carrier structure, wherein the method comprises: positioning the heat conductor within the coil, wherein the heat conductor is spaced apart from the coil; providing a fluid material between the heat conductor and the coil to form a precursor inner core; and solidifying the fluid material of the precursor inner core to form a magnetic inner core of a first material, wherein the first material has a first thermal conductivity, and the heat conductor is of a second material having a second thermal conductivity that is greater than the first thermal conductivity.

13. The method according to claim 12, wherein the fluid material is a fluid metal-powder compound.

14. The method according to claim 13, wherein the fluid material is also provided outside of the coil to form a precursor outer core connected to the precursor inner core.

15. The method according to claim 14, wherein the heat conductor and the coil are placed in a mold and the fluid material is provided between the coil and the mold to form the precursor outer core.

16. An inductor comprising: a magnetic inner core; a coil wound around the inner core; and a magnetic outer core extending on the outside of the coil and connecting to the inner core, wherein the inner core has a cylindrical geometry defining a central axis, and the outer core is located at the central axis, a heat conductor arranged within the inner core and the outer core and accessible from outside the outer core and the coil for conducting heat from the inner core to outside the inner core, wherein the inner core is of a first material having a first thermal conductivity, and the heat conductor is of a second material having a second thermal conductivity that is greater than the first thermal conductivity.

17. The inductor according to claim 16, wherein the first material is a solid metal-powder compound.

18. The inductor according to claim 16, wherein the thermal conductivity of the second material is at least three times greater than the thermal conductivity of the first material.

19. The inductor according to claim 16, wherein the heat conductor extends through the inner core and the outer core and is accessible from outside the outer core on opposite sides of the outer core.

20. The inductor according to claim 16, wherein the heat conductor is located at the central axis.

21. The inductor according to claim 16, wherein the outer core is of the same material as the inner core, and the inner core and the outer core jointly form a monolithic structure.

22. The inductor according to claim 16, wherein the inductor further comprises: a heatsink coupled to the heat conductor and configured to receive heat from the heat conductor.

23. The inductor according to claim 22, wherein the heatsink comprises: a cover and a first heat-transfer plate coupled to the heat conductor and interconnecting the heat conductor and the cover for conducting heat from the heat conductor to the cover, and the cover comprises heat dissipating fins.

24. The inductor according to claim 23, wherein the cover comprises: a side panel; wherein the first heat-transfer plate interconnects the heat conductor and the side panel for conducting heat from the heat conductor to the side panel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] A more complete understanding of the abovementioned and other features and advantages of the proposed technology will be apparent from the following detailed description in conjunction with the appended drawings, wherein:

[0073] FIGS. 1a-c schematically illustrate a side view, a longitudinal cross-sectional view, and a transverse cross-sectional view, respectively, of an embodiment of the proposed technology.

[0074] FIG. 2 schematically illustrates a longitudinal cross-sectional view of another embodiment of the proposed technology.

[0075] FIG. 3 schematically illustrates a longitudinal cross-sectional view of another embodiment of the proposed technology.

[0076] FIG. 4 schematically illustrates a longitudinal cross-sectional view of another embodiment of the proposed technology.

[0077] FIG. 5 schematically illustrates a longitudinal cross-sectional view of another embodiment of the proposed technology.

DETAILED DESCRIPTION

[0078] FIGS. 1a-c schematically illustrate an embodiment of an inductor 10. The inductor has a magnetic inner core 14 of a solid metal-powder compound. A coil 18 of an electrical conductor 22 in the form of insulated copper wire is wound around the inner core 14. A heat conductor 20 in the form of a single piece of solid aluminum alloy is arranged within the inner core 14. The heat conductor 20 is loosely fitted within the inner core 14. In an alternative embodiment it has been press fitted into the inner core 14.

[0079] As can be seen in FIGS. 1a-c, the inner core 14 has a cylindrical geometry defining a central axis 24. The inner core 14 forms a through-going central hole 26 aligned with, centered on, and extending along the central axis 24. The central hole 26 and the heat conductor 20 conform to one another by matching circular-cylindrical geometries, as can be seen in FIG. 1c. The central axis 24 of the inner core 14, the central hole 26, and the heat conductor are colinear. The transverse cross section of the inner core 14 has an area that is three times greater than the area of the transverse cross section of the heat conductor 20.

[0080] The inductor 10 has a magnetic outer core 16 extending on the outside of the coil 18. The outer core 16 and the inner core 14 jointly form a monolithic core structure 12 of the solid metal-powder compound. The two cores 14 and 16 are connected at the horizontal dashed lines indicated in FIG. 1b.

[0081] The heat conductor 20 is a monolithic rod that extends through the inner core 14. The heat conductor 20 extends from the inner core 14 into the outer core 16 and is accessible from outside the outer core 14 on opposite sides of the outer core 16. Thus, it is also accessible from outside the inner core 10 and the coil 18 on opposite sides of the inner core 14. This way, the heat conductor can conduct heat from the inner core 14 to outside the inner core 14. For example, the heat conductor 20 can be connected to a separate external heatsink (not shown).

[0082] The aluminum alloy of the heat conductor 20 has a thermal conductivity that is more than three times greater than the thermal conductivity of the solid metal-powder compound of the inner core 14.

[0083] The inductor 10 in FIGS. 1a-c is manufactured from a prefabricated core structure 12 by winding the electrical conductor 22 on the prefabricated core structure 12 to form the coil 18. The coil 18 then defines the inner core 14 and the outer core 16. The above-described central hole 26 has been formed in the manufacturing of the core structure 12. The heat conductor 20 is provided by loosely fitting the rod of aluminum alloy in the central hole 26.

[0084] FIG. 2 schematically illustrates another embodiment of an inductor 10. It has the features of the inductor described in relation to FIG. 1. Additionally, the coil 18 has a carrier structure 28 of cured epoxy resin that embeds and supports the electrical conductor 22. The outer core 16 surrounds the coil 18 completely and connects to the inner core 14 at opposite ends of the inner core 14, thus forming a closed loop with the inner core 14.

[0085] In the manufacturing of the inductor 10 in FIG. 2, the coil 18 and the core structure 12 are prefabricated with the central hole 26 formed together with the core structure 12. The heat conductor 20 is provided by press fitting a rod of aluminum alloy into the central hole 26. Alternatively, the coil 18 and the core structure 12 are prefabricated, and molten aluminum alloy is cast into the central hole 26 such that the molten aluminum alloy contacts the inner core 14. The molten aluminum alloy is cooled and solidifies to form a heat conductor 20 of solid aluminum alloy.

[0086] FIG. 3 schematically illustrates another embodiment of an inductor 10. It has the features of the inductor described in relation to FIG. 2. Additionally, the inductor 10 has a heatsink 30 that is external to the inner core 14, the coil 18, and the outer core 16. The heatsink 30 encloses the outer core 16 and the heat conductor 20 contacts the heatsink 30 such that heat is conducted away from the heat conductor 20. In alternative embodiments, the heat conductor 20 may be joined to the heatsink 30. For example, it may be connected by a screw fit or a weld. It is understood that the heatsink 30 is external to the inner core 14, the coil 18, and the outer core 16.

[0087] The heatsink 30 as such defines a cylinder with circular cross-section and a closed end, thus forming a mold 30 that can hold a liquid. The heat conductor 20 contacts the heatsink 30 at the closed end.

[0088] In an alternative embodiment, the inductor 10 is a gapped inductor with the inner core 14 forming an air gap 48. The air gap 48 is filled with a cured epoxy resin. The air gap 48 extends from the coil 18 to the heat conductor 20 transversely to the central axis 24 and divides the inner core 14 in two inner core portions 50 that are separated by the air gap 48. The inductor in FIG. 3 can be manufactured by placing the heat conductor 20 and the coil in the mold 30 formed by the heatsink 30. The heat conductor 20 is positioned within the coil 18 and contacts the mold 30. A fluid metal-powder compound composed of a thermosetting resin carrying metal powders is provided. In an alternative embodiment, an epoxy resin is used instead of the thermosetting resin. This fluid material is in liquid form and is cast into the mold 30 such that it is introduced between the heat conductor 20 and the coil 18 to form a precursor inner core and between the coil 18 and the mold 30 to form a precursor outer core that surrounds the coil 18. In an alternative embodiment, the fluid material is injected into the mold 30 under pressure.

[0089] The fluid material contacts the conductor 20, the coil 18, and the mold 30. The precursor inner core and the precursor outer core join seamlessly at opposite ends of the coil 18.

[0090] The fluid material is then heated, for example by placing the mold 30 in an oven, such that it cures and solidifies, thus forming the abovementioned solid metal-powder compound. If the fluid metal-powder compound instead is based on an epoxy resin, the fluid material is rested until it is fully cured. The precursor inner core forms the inner core 14, which adheres to the heat conductor 20 and the coil 18. The precursor outer core forms the outer core 16, which adheres to the coil 18 and the mold 30, which also forms the heatsink 30.

[0091] In the alternative embodiment in which the inductor 10 is a gapped inductor, the inductor is manufactured as described above with the fluid metal-powder compound being based on an epoxy resin. The casting of the fluid material is interrupted, and a thin layer of pure epoxy resin is cast between the coil 18 and the heat conductor 20, whereafter the casting of the fluid material is resumed. Once cured, the pure epoxy resin forms the airgap 48.

[0092] The inductor in FIG. 3 can alternatively be manufactured by placing the heat conductor 20 and the coil in the mold 30 formed by the heatsink 30. The heat conductor 20 is positioned within the coil 18 and contacts the mold 30. A fluid metal-powder compound in powder-form is provided. This fluid material is potted and compacted in the mold 30 such that it is introduced between the heat conductor 20 and the coil 18 to form a precursor inner core and between the coil 18 and the mold 30 to form a precursor outer core that surrounds the coil 18. The fluid material contacts the conductor 20, the coil 18, and the mold 30. The precursor inner core and the precursor outer core join seamlessly at opposite ends of the coil 18.

[0093] The fluid metal-powder compound includes a binder in powder form. The fluid material is heated such that the binder melts. After cooling, the binder holds the resulting solid metal-powder compound together. In an alternative embodiment, the fluid metal-powder compound is composed of metal powders that is sintered in the mold 30 to form the solid metal-powder compound.

[0094] The precursor inner core forms the inner core 14, which contacts the heat conductor and the coil 18. The precursor outer core forms the outer core 16, which contacts the coil 18 and the mold 30.

[0095] In the embodiment of FIG. 3, the mold 30 is an integral part and constitutes the heatsink 30 of the inductor 10. In an alternative embodiment, the outer core 16 together with the heat conductor 10, the inner core 14, and the coil 18 are removed from the mold 30, thus providing an inductor 10 having the features described in relation to FIG. 2. Instead of the heat connector being press fitted into the central hole 26, the inner core has now been formed around the heat conductor 20.

[0096] FIG. 4 schematically illustrate another embodiment of an inductor 10. The inductor 10 has the features described in relation to FIG. 2. Additionally, it has an external heatsink 30 with a cover 34 that forms heat dissipating fins 32. The cover 34 is a single piece of extruded aluminum alloy that encircle the outer core 16 and form a cavity 36 in which the outer core 16 is positioned. As described above, the heat conductor 20 has a cylindrical geometry defining a central axis 24 and the cavity 36 has a cylindrical geometry defining a colinear central axis 24.

[0097] The cover 34 conforms to and contacts the outer core 16 such that heat can be conducted to the cover 34. The cover 34 has a first opening 38 and a second opening 40 to the cavity 36. The outer core 16 together with the heat conductor 20, the inner core, and the coil 18 can be removed from or inserted into the cavity 36 via the first opening 38 or the second opening 40.

[0098] The heatsink 30 has a first heat-transfer plate 42 that is connected to the heat conductor 20 by a screw at the first opening 38. The heatsink 30 further has a second heat-transfer plate 44 that is connected to the heat conductor 20 by a screw at the second opening 40. This way, the heatsink 30 connected to the heat conductor 20 on opposite sides of the heat conductor 20. Each of the first heat-transfer plate 42 and the second heat-transfer plate 44 interconnects the heat conductor 20 and the cover 34 such that heat can be conducted from the heat conductor 20 to the cover 34. Each of the first heat-transfer plate 42 and the second heat-transfer plate 44 also contacts the outer core 16 such that they conduct heat from the outer core 16 to the cover 34. The first heat-transfer plate 42 covers the first opening 38 leading to the cavity 36, and second heat-transfer plate 44 covers the second opening 40 leading to the cavity 36.

[0099] The inductor 10 shown in FIG. 4 can be manufactured by inserting the inductor 10 described in relation to FIG. 2 into the cavity 36 formed by the cover 34. The first heat-transfer plate 42 and the second heat-transfer plate 44 are then attached to the heat conductor and connected to the cover 34 as described above.

[0100] FIG. 5 schematically illustrate another embodiment of an inductor 10. The inductor 10 has the features described in relation to FIG. 2. Additionally, it has an external heatsink 30 with a side panel 46 that forms heat dissipating fins 32. The side panel 46 is a single piece of extruded aluminum alloy.

[0101] The side panel conforms to and contacts the outer core 16 such that heat can be conducted to the side panel 46. The heatsink 30 has a first heat-transfer plate 42 that is connected to the heat conductor 20 by a screw at one end of the heat conductor 20. The heatsink 30 further has a second heat-transfer plate 44 that is connected to the heat conductor 20 by a screw at the opposite end of the heat conductor 20. Each of the first heat-transfer plate 42 and the second heat-transfer plate 44 interconnects the heat conductor 20 and the side panel 46 such that heat can be conducted from the heat conductor 20 to the side panel 46. Each of the first heat-transfer plate 42 and the second heat-transfer plate 44 also contacts the outer core 16 such that they conduct heat from the outer core 16 to the side panel 46.

[0102] In an alternative embodiment, the inductor has four side panels that jointly outline a cavity in which the outer core is positioned. The four side panels are arranged in pairs that are on opposite sides of the outer core 16. Each side panel is arranged and connected as the above-described side panel 46.

[0103] The inductor 10 shown in FIG. 5 can be manufactured from the inductor 10 described in relation to FIG. 2 by attaching the first heat-transfer plate 42 and the second heat-transfer plate 44 to the heat conductor 20 and connecting them to the side panel 46 as described above.

ITEM LIST

[0104] 10 inductor [0105] 12 core structure [0106] 14 inner core [0107] 16 outer core [0108] 18 coil [0109] 20 heat conductor [0110] 22 electric conductor [0111] 24 central axis of inner core, heat conductor, and cavity [0112] 26 central hole [0113] 28 carrier structure of coil [0114] 30 heatsink or mold [0115] 32 heat dissipating fins [0116] 34 cover [0117] 36 cavity [0118] 38 first opening [0119] 40 second opening [0120] 42 first heat-transfer plate [0121] 44 second heat-transfer plate [0122] 46 side panel [0123] 48 air gap [0124] 50 inner core portions

EMBODIMENTS

[0125] 1. An inductor (10) comprising: [0126] a magnetic inner core (14); [0127] a coil (18) wound around the inner core (14); and [0128] a heat conductor (20) arranged within the inner core (14) and accessible from outside the inner core (14) and the coil (18) for conducting heat from the inner core (14) to outside the inner core (14), wherein the inner core (14) is of a first material having a first thermal conductivity, and the heat conductor (20) is of a second material having a second thermal conductivity that is greater than the first thermal conductivity. [0129] 2. The inductor according to embodiment 1, wherein the first material is a solid metal-powder compound. [0130] 3. The inductor according to embodiment 2, wherein the thermal conductivity of the second material is at least three times, five times, or ten times greater than the thermal conductivity of the first material. [0131] 4. The inductor according to embodiment 2 or 3, wherein the heat conductor (20) extends through the inner core (14) and is accessible from outside the inner core (10) on opposite sides of the inner core (14). [0132] 5. The inductor according to any of the embodiments 2 to 4, wherein the inner core (14) has a cylindrical geometry defining a central axis (24), and the heat conductor (20) is located at the central axis (24). [0133] 6. The inductor according to any of the embodiments 2 to 5, wherein the inductor (10) further comprises: [0134] a magnetic outer core (16) extending on the outside of the coil (18) and connecting to the inner core (14), wherein the outer core (16) is of the same material as the inner core (14), and the inner core (14) and the outer core (16) jointly form a monolithic structure. [0135] 7. The inductor according to any of the embodiments 2 to 6, wherein the inductor (10) further comprises: [0136] a heatsink (30) coupled to the heat conductor (20) and configured to receive heat from the heat conductor (20). [0137] 8. The inductor according to embodiment 7, wherein the heatsink (30) comprises: a cover (34) and a first heat-transfer plate (42) coupled to the heat conductor (20) and interconnecting the heat conductor (20) and the cover (34) for conducting heat from the heat conductor (20) to the cover (34), and the cover comprises heat dissipating fins (32). [0138] 9. The inductor according to embodiment 8, wherein the cover (34) encircles the outer core (16) and form a cavity (36) in which the outer core (16) is positioned, the cover (34) has a first opening (38) to the cavity (36) and the heat conductor (20) is coupled to the first heat-transfer plate (42) at the first opening (38). [0139] 10. The inductor according to embodiment 8, wherein the cover (34) comprises: a side panel (46); wherein the first heat-transfer plate (42) interconnects the heat conductor (20) and the side panel (46) for conducting heat from the heat conductor (20) to the side panel (46). [0140] 11. A method for manufacturing an inductor (10) comprising a coil (18) and a heat conductor (20), wherein the method comprises: [0141] positioning the heat conductor (20) within the coil (18), wherein the heat conductor (20) is spaced apart from the coil (18); [0142] providing, a fluid material between the heat conductor (20) and the coil (18) to form a precursor inner core (14); and [0143] solidifying the fluid material of the precursor inner core to form a magnetic inner core (14) of a first material, [0144] wherein the first material has a first thermal conductivity, and the heat conductor (20) is of a second material having a second thermal conductivity that is greater than the first heat conductivity. [0145] 12. The method according to embodiment 11, wherein the fluid material is a fluid metal-powder compound. [0146] 13. The method according to embodiment 12, wherein the fluid material is also provided outside of the coil (18) to form a precursor outer core connected to the precursor inner core. [0147] 14. The method according to embodiment 13, wherein the heat conductor (20) and the coil are placed in a mold (30) and the fluid material is provided between the coil (18) and the mold (30) to form the precursor outer core.