Magnetic components featuring graphite laminate layers for enhanced heat transfer and dissipation

Abstract

An air gap is formed in the magnetic core of the inductor, and heat is prevented from being transferred from the upper magnetic core to the lower magnetic core through the air gap. The cross section of the magnetic core is E-shaped, a wire is wound on the central column or the framework, and no wire is wound on the left supporting leg and the right supporting leg. The graphite flakes are coated with adhesives, and the graphite flakes are attached to the outer sides of the left supporting foot and the right supporting foot. The graphite adhesive laminate spans the air gap, enabling heat transfer through the air gap. The graphite flake is not attached to the skeleton. Thermally conductive particles, such as carbon nanotubes, may be added to the binder. A plurality of inductors may be laterally stacked together. The radiator connected to the lower magnetic core can conduct heat through the graphite flakes crossing the air gaps, and therefore heat generated by the upper magnetic core is dissipated.

Description

W O 2 02 6 / 14 37 53 A l IM IIM __ _I I_ _I III I_ M (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (10) International Publication Number (43) International Publication Date WO 2026 / 143753 Al 09 July 2026 (09.07.2026) WIPO I PCT (19) World Intellectual Property Organization International Bureau (51) International Patent Classification: H01F27 / 24 (2006.01) H01F27 / 00 (2006.01) (21) International Application Number: PCT / CN2025 / 071070 (22) International Filing Date: 07 Januaiy 2025 (07.01.2025) (25) Filing Language: English (26) Publication Language: English (30) Priority Data: 19 / 005,044 30 December 2024 (30.12.2024) US (71) Applicant: HONG KONG APPLIED SCIENCE AND TECHNOLOGY RESEARCH INSTITUTE COMPA­ NY LIMITED [CN / CN]; 5 / F, Photonics Centre, 2 Science Park East Avenue, Hong Kong Science Park, Shatin, N.T., Hong Kong (CN). (72) Inventors: LIMBU, Pratik; Flat E, 5 / F, Pak Yee Building, Kau Yuk Road, Yuen Long, N.T., Hong Kong (CN). PON- NUVELU, Bhoopal;9E, Ping Long Village Lam Tsuen Valley, Tai Po, N.T., Hong Kong (CN). LI, Tin Ho; 22D, Block 5A, Pavilia Farm, Sha Tin., Hong Kong (CN)- (74) Agent: CHINA TRUER IP; Room 1104, Building 2, Excellence Meilin Central Plaza (North Area), No. 128 Zhongkang Road, Meidu Community, Meilin Street, Futian District, Shenzhen, Guangdong 518049 (CN). (81) Designated States (unless otherwise indicated, for every kind of national protection available) '. AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ, CA, CH, CL, CN, CO, CR, CU, CV CZ, DE, DJ, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, EL, IN, IQ, IR, IS, IT, JM, JO, JP, KE, KG, KH, KN, KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY; MA, MD, MG, MK, MN, MU, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, (54) Title: MAGNETIC COMPONENTS FEATURING GRAPHITE LAMINATE LAYERS FOR ENHANCED HEAT TRANSFER AND DISSIPATION 754 600 FIG. 18 (57) Abstract: An inductor has a core with an airgap that prevents heat transfer across the air gap from an upper core to a lower core. The cores have an E-shaped cross section, with a center post or bobbin that wire is wrapped around, and a left leg and a right leg that are not wrapped with wires. Adhesive is applied to a graphite sheet to attach the graphite sheet to outer sides of the left and right legs. The graphite-adhesive laminate sheet crosses the air gap, allowing heat to be transferred across the air gap. Graphite sheets are not attached to the bobbin. Thermally -conductive particles such as caibon nanotubes can be added to the adhesive. Several inductors can be stacked together laterally. A heat sink attached to the lower core can dissipate heat generated by the upper core by heat transfer through the graphite sheet crossing the air gap. [Continued on next page] wo 2026 / 143753 Al |_|_|_|||_|_ RS, RU, RW, SA, SC, SD, SE, SG, SK, SL, ST, SY SY; TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UY,UZ, VC, VN, WS, ZA, ZM, ZW. (84)Designated States (unless otherwise indicated, for every kind of regional protection available)'. ARIPO (BW, CV, GH, GM, KE, LR, LS, MW, MZ, NA, RW, SC, SD, SL, ST, SZ, TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, E, IS, IT, LT, LU, LV, MC, ME, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG). Published: — -with international search report (Art. 21(3)) WO 2026 / 143753 PCT / CN2025 / 071070 1 Magnetic Components Featuring Graphite Laminate Layers for Enhanced Heat Transfer and Dissipation FIELD OF THE INVENTION

[0001] This invention relates to inductors with magnetic cores, and more particularly to heat transfer across an air gap in an inductor core. BACKGROUND OF THE INVENTION

[0002] Magnetic components such as inductors and transformers are often used in power converters such as Switched-Mode Power Supplies (SMPS).

[0003] Figure 1 shows an inductor with a magnetic core. An inductor has a long insulated wire wrapped around a magnetic core. A transformer is a type of inductor with two or more windings around the core, such as a primary winding and a secondary winding that are electrically isolated but coupled magnetically. Traditionally, the magnetic core is made of iron or ferrite and is shaped as a cylinder.

[0004] A more advanced inductor has an E-shaped core or E-core. In Fig. 1, wire 120 are wrapped around center post or bobbin 106 of an E-core. The E-core has upper core 104 and lower core 108 that each have a cross-section that looks like the letter E. For example, upper core 104 has a cross section that looks like a letter E rotated to point downward, while lower core 108 has a cross section that looks like a letter E rotated to point upward (Fig. 4).

[0005] Bobbin 106 is the center of the E cross sections while the sides of upper core 104 and lower core 108 partially surround wires 120. Bobbin 106can be square or round in the many variations of E-cores. Wire 120 is more easily wrapped around a round bobbin 106 than a square bobbin 106. E-core inductors can provide lower core losses even at higher temperature, higher efficiency due to better magnetic coupling, lower manufacturing costs, a compact design to overcome space constraints, and easier assembly for prototyping and testing.

[0006] Upper core 104 and lower core 108 are separated by air gap 100. Air gap 100 can prevent saturation and allow for a higher magnetic flux and energy storage.

[0007] Figure 2 shows an inductor core. Wires 120 have been removed in Fig. 2 to show upper core 104 and lower core 108 in better detail. Rather than being rectangular, bobbin 106 can have a cylindrical shape to better allow wires 120 to wrap around in a coil shape. Air gap 100 is present in bobbin 106 as well as the two sides of upper core 104 and lower core 108.

[0008] Figure 3 shows the inductor mounted to a heat sink. Heat sink 112 canbe attached to the bottom of lower core 108, either directly as shown or indirectly through a Printed-Circuit Board (PCB) that has metal heat pipes or other heat transfer components passing through the PCB to conduct heat from lower core 108 to heat sink 112.

[0009] Note that upper core 104 is not attached to any heat sink. High-density power converters often are cramped and do not allow for heat sinks on both upper and lower cores of an inductor. WO 2026 / 143753 PCT / CN2025 / 071070 2

[00010] Figure 4 is a cross-section of the inductor of Figs. 1-3. Upper core 104 is E-shaped and is separated from E-shaped lower core 108 by air gap 100. Bobbin 106 is also divided by air gap 100. Wires 120 (not shown) are wrapped around bobbin 106 in voids 116 between bobbin 106 and the ends of upper core 104 and lower core 108.

[00011] Heat sink 112 is attached to the bottom of lower core 108. Heat sink 112 can remove heat from lower core 108. Air flow can be forced across fins on the lower surface ofheat sink 112 to enhance heat removal. However, heat generated in upper core 104 cannot easily be removed to heat sink 112 because air gap 100 hinders heat transfer.

[00012] Figure 5 shows heat transfer within the inductor of Figs. 1-4. When current passes through wires 120, wires 120 heat up due to resistance in the long wires. Also, when Alternating Current (AC) is applied to wires 120, the magnetic flux reverses as the AC current changes direction. These magnetic flux reversals can have hysteresis and can cause eddy currents within upper core 104 and lower core 108. Heating from these eddy currents is greatest where the magnetic flux is the most dense, in bobbin 106.

[00013] This heat generated by resistances in wires 120 and by flux reversals in bobbin 106 increases the temperature of upper core 104 and lower core 108. However, heat from lower core 108 can be transferred to heat sink 112, reducing the temperature of lower core 108. However, air gap 100 prevents or significantlyreduces heat transfer from upper core 104 to lower core 108. Thus upper core 104 can have a higher temperature than lower core 108.

[00014] Upper core 104 can be as much as 40 C higher in temperature than lower core 108. This higher temperature in upper core 104 is undesirable since overheating can cause failures and reduce service lifetime of the inductor and other nearby components.

[00015] What is desired is an inductor with better heat transfer. An indictor with enhanced heat transfer across an air gap between upper and lower E-cores is desirable. An air-gap inductor with a laminate coating to transfer heat across the air gap is desired. BRIEF DESCRIPTION OF THE DRAWINGS

[00016] Figure 1 shows an inductor with a magnetic core.

[00017] Figure 2 shows an inductor core.

[00018] Figure 3 shows the inductor mounted to a heat sink.

[00019] Figure 4 is a cross-section of the inductor of Figs. 1-3.

[00020] Figure 5 shows heat transfer within the inductor of Figs. 1 -4.

[00021] Figure 6shows an E-core inductor with a heat-transfer laminate attached to the outer faces of the core sides.

[00022] Figure 7 shows an E-core inductor with a graphite-adhesive laminate attached to the outer surfaces of E-core. WO 2026 / 143753 PCT / CN2025 / 071070 3

[00023] Figure 8 is a cross-section of an E-core inductor with graphite sheets attached to outer surfaces to transfer heat across the air gap.

[00024] Figure 9 highlights heat transfer across the air gap by the graphite sheets.

[00025] Figure 10 shows graphite laminate sheets also attached to front and back surfaces of the side legs of the E-cores.

[00026] Figure 11 shows graphite laminate sheets attached to all outer surface of the E-core.

[00027] Figure 12 shows the graphite laminate sheet in more detail.

[00028] Figure 13 shows a graphene layer in graphite.

[00029] Figure 14 shows a process for forming an adhesive layer on a graphite sheet to form a graphite laminate sheet.

[00030] Figure 15 shows the graphite laminate layer in moredetail.

[00031] Figures 16A-16B show attaching a single graphite laminate sheet to four outer sides of the inductor.

[00032] Figure 17 highlights the single large graphite sheet being applied to upper core 32 and lower core 34.

[00033] Figure 18 shows 3 inductor cores laminated together with laminate graphite sheets.

[00034] Figure 19 shows a stacked inductor with graphite rings between inductor cores.

[00035] Figure 20 shows the stacked inductor attached to a heat sink.

[00036] Figures 21A-21B shows different core types.

[00037] Figure 22 shows a stacked inductor with five cores. DETAILED DESCRIPTION

[00038] The present invention relates to an improvement in inductors. The following description is presented to enable one of ordinary skill in the art to make and use the invention as provided in the context of a particular application and its requirements. Various modifications to the preferred embodiment will be apparent to those with skill in the art, and the general principlesdefined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed.

[00039] Figure 6 shows an E-core inductor with a heat-transfer laminate attached to the outer faces of the core sides. Inductor 30 is an E-core inductor with upper and lower cores separated by air gap 10. A long wire (not shown) is wrapped around the bobbin 106 of inductor 30. The side legs of the upper and lower cores partially surround the wire coil wrapped around the bobbin 106.

[00040] Graphite sheets 22, 24, 26, 28 are laminate sheets, each with a graphite layer and an adhesive layer laminated together. Graphite sheet 22 has its adhesive layer pressed into the outer surface of the right side legs of the upper and lower cores. Graphite sheet 24 has its adhesive layer pressed into the outer surface of the left sidelegs of the upper and lower cores. Graphite sheet 26 has its adhesive layer pressed into the outer top surface WO 2026 / 143753 PCT / CN2025 / 071070 4 of the upper core, while graphite sheet 28 has its adhesive layer pressed into the outer top surface of the lower core.

[00041] Graphite sheet 22 straddles air gap 10 that separates the right legs of the upper and lower cores. Likewise, graphite sheet 24 straddles air gap 10 that separates the left legs of the upper and lower cores. The adhesive layer ensures that the overlaying graphite layer of the laminate sheet sticks to the outer surfaces of the magnetic core.

[00042] Figure 7 shows an E-core inductor with a graphite-adhesive laminate attached to the outer surfaces of E-core. Inductor 30 has graphite sheets 22, 24, 26, 28 attached to four outer surfaces of the upper and lower E-cores. Graphite has good heat transfer characteristics, allowing heat to be transferred from the upper core across air gap 10 to the lower core. Graphite sheet 22crosses air gap 10 in the right leg of the E-cores, while graphite sheet 24 crosses air gap 10 on the left leg of the E-cores.

[00043] Figure 8 is a cross-section of an E-core inductor with graphite sheets attached to outer surfaces to transfer heat across the air gap. Upper core 32 and lower core 34 are E-shaped ferrite cores with a long wire (not shown) wrapped around their bobbins. Graphite sheet 22 is attached to the outer surface of the right legs of upper core 32 and lower core 34 so that graphite sheet 22 covers the right side of air gap 10. Graphite sheet 24 is attached to the outer surface of the left legs of upper core 32 and lower core 34 so that graphite sheet 24 covers the left side of air gap 10.

[00044] Graphite sheet 26 is attached by its adhesive to the top surface of upper core 32, while graphite sheet 28 is attached by its adhesive to the bottom surface of lower core 34. Heat sink 122 can be attached to graphite sheet 28 by another adhesive layer or can simply bepressed together and held in place by connectors or fasteners such as screws or bolts.

[00045] Figure 9 highlights heat transfer across the air gap by the graphite sheets. During operation, the bobbins of upper core 32 and lower core 34 heat up due to eddy currents in the ferrite core and due to resistance heating of the long wires wrapped around the bobbin. This heat from the bobbin flows outward through upper core 32 to the left and right side legs of upper core 32. Some heat from the bobbin also is conducted to graphite sheet 26 and then flows along the top of the inductor and into graphite sheets 22, 24 on the sides.

[00046] Some heat conducted along top graphite sheet 26 and more heat conducted from the left side leg of upper core 32 is conducted into left graphite sheet 24. This heat in left graphite sheet 24 is conducted downward across air gap 10 and into the left leg of lower core 34, or into bottom graphite sheet 28 and into heat sink 112. Thus heat from the bobbin of uppercore 32 is conducted through graphite sheets 26, 24, 28 and into heat sink 112, where cooling fins can dissipate the heat into forced air.

[00047] Other heat conducted rightward along top graphite sheet 26 and more heat conducted from the right side leg of upper core 32 is conducted into right graphite sheet 22. This heat in right graphite sheet 22 is conducted downward across air gap 10 and into the right leg of lower core 34, or into bottom graphite sheet 28 I WO 2026 / 143753 PCT / CN2025 / 071070 5 and into heat sink 112. Thus heat from the bobbin of upper core 32 is also conducted through graphite sheets 26, 22, 28 and into heat sink 112, where cooling fins can dissipate the heat into forced air.

[00048] Graphite sheets 22, 24 bridge air gap 10, allowing heat transfer from upper core 32 to lower core 34. Heat is more uniformly distributed within the inductor, reducing hot spots and thermal failures. Heat sink 112 can remove this heat when a fan forces air to flow across fins on heatsink 112.

[00049] Figure 10 shows graphite laminate sheets also attached to front and back surfaces of the side legs of the E-cores. Front graphite sheet 52 has a back-facing adhesive layer that is pressed into the front face of upper core 32 and lower core 34. Back graphite sheet 54 has a front-facing adhesive layer that is pressed into the back face of upper core 32 and lower core 34. Front graphite sheet 52 and back graphite sheet 54 are not pressed into the bobbin.

[00050] Figure 11 shows graphite laminate sheets attached to all outer surface of the E-core. While graphite laminate sheets are not attached to the bobbin where the long wire is wound around, graphite sheets 22, 24, 26 attach to the outer top and side surfaces of upper core 32, while graphite sheets 22, 24, 28 attach to the outer bottom and side surfaces of lower core 34. Graphite sheets 22, 24 cross the air gap.

[00051] Front graphite sheet 52 is a square ring attached to the front surfaces of upper core 32 and lowercore 34. Back graphite sheet 54 is a square ring attached to the back or rear surfaces of upper core 32 and lower core 34.

[00052] Figure 12 shows the graphite laminate sheet in more detail. Graphite sheet 22 is a laminate having graphite layer 70 and adhesive layer 74. Adhesive layer 74 can be an acrylic tape that is attached to graphite layer 70. The thermal conductivity of adhesive layer 74 can be enhanced by adding thermally conductive particles 76 to adhesive layer 74. For example, thermally conductive particles 76 can be carbon nano tubes.

[00053] Figure 13 shows a graphene layer in graphite. Graphite has many layers of graphene 102 that are stacked together like a stack of papers. However, clumps of stacked layers of graphene 102 may have different orientations. Graphene 102 has carbon atoms in a flat planar hexagonal pattern. Graphite has good heat transfer and electrical conductivity.

[00054] Ferrite cores provide good magnetic properties but are electrically insulating. Ifconductive graphite layers 22, 24 are placed within or in-between the air gap, the magnetic flux across the air gap is affected, reducing the effective saturation. Eddy current may be induced on the conductor resulting in higher power loss. When graphite layers 22, 24 are around or just outside the air gap, there is less interference with the magnetic field, avoiding eddy current losses. Since cores are often made of material that does not conduct electricity, such as ferrite, having an electric conductor such as graphite layers 22, 24 straddle air gap 10 does not cause any electrical shorts or problems.

[00055] Figure 14 shows a process for forming an adhesive layer on a graphite sheet to form a graphite laminate sheet. Graphite layer 70 can be a graphite sheet that is commercially available. As graphite layer 70 is WO 2026 / 143753 PCT / CN2025 / 071070 6 rolled along, such as by a conveyor, nozzle 77 squirts liquid adhesive onto the top surface of graphite layer 70, forming adhesive layer74 on top of graphite layer 70. Thermally conductive particles 76 can be mixed with the liquid adhesive before the mixture is input to nozzle 77. Mechanical mixing could be supplemented with ultrasonic mixing to better disperse thermally conductive particles 76 within the adhesive.

[00056] Thus adhesive layer 74 contains thermally conductive particles 76 that are randomly distributed within adhesive layer 74.

[00057] Figure 15 shows the graphite laminate layer in more detail. Adhesive layer 74 has been printed onto the top of graphite layer 70. Micro bumps 78 are formed on adhesive layer 74 to enhance adhesion. Micro bumps 78 can be adhesive dots or bumps that are printed onto the top of adhesive layer 74 by stencil, special, or 3D printing. A matrix of additional nozzles could be used to print micro bumps 78 onto adhesive layer 74.

[00058] Figures 16A-16B show attaching a single graphite laminate sheet to four outer sides of the inductor. In Fig. 16A, a single large graphite sheetwith adhesive applied is folded on the daashed lines. Thus folds are made between sections A, B, C, D, which correspond to graphite sheets 24, 26, 22, 28, respectively.

[00059] Cuts are made on the solid lines. Thus cuts are made between sections A2, B2, C2, and D2 back graphite sheet 54. Cuts are also made between sections Al, Bl, Cl, and DI in front graphite sheet 52.

[00060] In Fig. 16B, after the cuts are made to the single large graphite sheet, this sheet is applied to the outer surfaces of upper core 32 and lower core 34. Section A forms left graphite sheet 24, while section B forms top graphite sheet 26. Section C forms right graphite sheet 22 and section D forms bottom graphite sheet 28 (not shown).

[00061] Once section A has been applied to the left legs of upper core 32 and to lower core 34, then section Al can be folded over the left front edge of upper core 32 and lower core 34 and pressed into the top front surface of upper core 32 and lower core 34 to form a portion offront graphite sheet 52. Section Cl can be folded over the right front edge of upper core 32 and lower core 34 to form the right portion of front graphite sheet 52.

[00062] Then section Bl can be folded over the top front edge of upper core 32 and pressed into the top front surface of upper core 32 to form a portion of front graphite sheet 52. Section D1 can be folded over the bottom front edge of lower core 34 to form the bottom portion of front graphite sheet 52.

[00063] Sections A2, C2 can likewise be folded over the back surfaces of upper core 32 and lower core 34, followed by folding section B2 over the back of upper core 32 and folding section D2 over the back of lower core 34. Thus a single graphite sheet can be folded and cut and applied to these outer surfaces of upper core 32 and lower core 34, forming graphite sheets 22, 24, 26, 28, 52, 54 from a single graphite sheet.

[00064] Figure 17 highlights the single large graphite sheet being applied to upper core 32 and lower core34. Section B can first be pressed into the top surface of upper core 32, such as by using a pressure roller or a squeegee. The pressure being applied helps to press the adhesive into the surface of upper core 32, flattening the i WO 2026 / 143753 PCT / CN2025 / 071070 7 graphite sheet and removing air bubbles. Then after section B is applied to form top graphite sheet 26, the large graphite sheet is folded over to the left surface of upper core 32 and lower core 34, and the pressure roller or squeegee presses this portion of the graphite sheet into the left surfaces of upper core 32 and lower core 34 to form left graphite sheet 24.

[00065] This use of the pressure roller or squeegee can continue to form right graphite sheet 22 and bottom graphite sheet 28. Then sections Al, Bl, Cl, DI can be folded over the front edges of upper core 32 and lower core 34 to form front graphite sheet 52. Finally sections A2, B2, C2, D2 can be folded over the back edges of upper core 32 and lower core 34 toform back graphite sheet 54.

[00066] Figure 18 shows 3 inductor cores laminated together with laminate graphite sheets. Inductor 30 can be formed by pressing graphite-adhesive sheets onto the outer surfaces of upper core 32 and lower core 34, forming right graphite sheet 22, left graphite sheet 24, top graphite sheet 26, bottom graphite sheet 28, front graphite sheet 52, and back graphite sheet 54. A larger graphite sheet such as shown in Fig. 16A-16B can be used to wrap inductor 30. All of graphite sheets 22, 24, 26, 28, 52, 54 have adhesive attached to inner surfaces facing cores 32, 34, such as front adhesive sheet 53 and back adhesive sheet 55.

[00067] Several assemblies identical to inductor 30 with its graphite sheets 22, 24, 26, 28, 52, 54 attached can be constructed. Front inductor 600 and back inductor 602 each have graphite sheets cladding their outer surfaces, as does inductor 30.

[00068] Front inductor 600 has right, left, top, and bottom graphite sheets attached. Frontinductor 600 also has front graphite sheet 652 attached by front adhesive ring 653, and back graphite sheet 654 attached by back adhesive ring 655.

[00069] Back inductor 602 has right, left, top, and bottom graphite sheets attached. Back inductor 602 also has front graphite sheet 752 attached by front adhesive ring 753, and back graphite sheet 754 attached by back adhesive ring 755.

[00070] Laminating rings 690, 790 are adhesive rings that laminate the core assemblies together. Laminating ring 690 has adhesive that adheres front inductor 600 to the front of inductor 30, while laminating ring 790 adheres back inductor 602 to the back of inductor 30. More particularly, laminating ring 690 is sandwiched between rear graphite sheet 654 and front graphite sheet 52. Likewise, laminating ring 790 is sandwiched between rear graphite sheet 54 and front graphite sheet 752.

[00071] Front inductor 600 can be pressed into inductor 30, causing adhesives in laminating ring 690 to be squeezed betweenrear graphite sheet 654 and front graphite sheet 52 to fonn a good bond with low contact resistance. Then the assembly of front inductor 600 and inductor 30 can be pressed into back inductor 602, causing adhesives in laminating ring 790 to be squeezed between rear graphite sheet 52 and front graphite sheet 752 to form a good bond with low contact resistance. WO 2026 / 143753 PCT / CN2025 / 071070 8

[00072] This pressing can be performed by loosely fitting inductor 30, front inductor 600, and back inductor 602 together with laminating rings 690, 790, and then applying force to the two ends of the entire sandwich of layers and inductor cores.

[00073] Graphite rings 52 allows for lateral heat transfer from the front of inductor 30. Graphite ring 654 allows for lateral heat transfer from front inductor 600.

[00074] Likewise, graphite ring 54 allows lateral heat transfer from the back of inductor 30. Graphite ring 752 allows lateral heat transfer from back inductor 602.

[00075] Thus heat can betransferred laterally among the laminated inductor cores through the intermediate graphite rings 52, 654, 54, 752.

[00076] Figure 19 shows a stacked inductor with graphite rings between inductor cores. Stacked inductor 90 has three inductor cores that are laminated together.

[00077] Inductor 30, front inductor 600, and back inductor 602 each have graphite-adhesive laminate sheets applied to their outer surface but not to their bobbins (bobbins) that wire 92 is wrapped around. Wire 92 is wrapped around all 3 bobbins for each winding.

[00078] Figure 20 shows the stacked inductor attached to a heat sink. A gap is shown in stacked inductor 90 between front inductor 600 and inductor 30 to expose wires 92 for viewing, but normally front inductor 600 would be pressed into inductor 30 with graphite ring 52 and its adhesive layers in between. All three of inductor 30, front inductor 600, and back inductor 602 are attached to heat sink 112. Heat generated by inductor 30 can travel downwardacross the air gap between upper core 32 and lower core 34 through right graphite sheet 22 and left graphite sheet 24. This heat then transfers to bottom graphite sheet 28 and then into heat sink 112 for dissipation by forced air.

[00079] Likewise, heat generated by front inductor 600 and back inductor 602 can cross their air gaps using graphite sheets 622, 722, (Fig. 18) and then be transferred downward into heat sink 112.

[00080] Graphite rings 52, 54 (Fig. 18) also allow heat transfer downward across the air gaps, but also allow heat transfer laterally from inductor 30 to front inductor 600 and to back inductor 602.

[00081] Inductor 30 in the middle would normally have more heat trapped since it cannot dissipate that heat laterally, only downward to a heat sink. But graphite ring 52 allows heat at the front surface of inductor 30 to be transferred laterally, cross the front air gap, and then down into heat sink 112 under inductor 30. Similarly, graphite ring 54 allows heat at theback surface of inductor 30 to be transferred laterally, cross the back air gap, then down into heat sink 112 under inductor 30. Thus more heat is effectively removed from inductor 30.

[00082] Figures 21A-21B shows different core types. Fig. 21A shows a traditional E-core that has a rectangular bobbin formed from the middle leg of upper core 32’. and lower core 34’. This rectangular bobbin or bobbin is undesirable since the wires are more difficult to wrap around a square bobbin. Also, having the WO 2026 / 143753 PCT / CN2025 / 071070 9 bobbin have the same thickness as the side legs causes the wires wrapped around the bobbin to stick out past the side legs.

[00083] Many variations of E-cores are available. Some E-cores have round bobbins, allowing for easier wire wrapping. Also the wires are less likely to break at the comers of the square bobbin when the bobbin is round. This improves reliability. The depth of the bobbin can be reduced to allow the left and right side legs to extend pastthe wires wrapped around the bobbin.

[00084] Fig. 21B shows a PQ core. A PQ core is a variation of the E-core and can be considered to be a type of E-core. In the PQ core, upper core 32” and lower core 34” are adjusted in shape. The center post or bobbin is round to allow for easier wire wrapping. The left and right side legs are deeper than the bobbin. The shape of the PQ core can be optimized for Switched-Mode Power Supplies (SMPS) or other AC applications.

[00085] When a PQ core is used, right graphite sheet 22 and left graphite sheet 24 can be applied as rectangles, but top graphite sheet 26 and bottom graphite sheet 28 may need to be cut to fit the shapes of the top of upper core 32” and the shape of lower core 34”. Alternately, a rectangle could be used for top graphite sheet 26 and for bottom graphite sheet 28, and the graphite sheet being larger or smaller than the top of upper core 32”. front graphite sheet 52 and back graphite sheet 54 may be deleted or reduced in size, suchas to only cover the left and right legs and not the top and bottom near the bobbin.

[00086] Figure 22 shows a stacked inductor with five cores. While Fig. 18 has shown three inductor cores connected laterally by two graphite rings, more cores can be included in stacked inductor 90’. In this example there are 5 cores and 4 graphite rings betw'een them. The size of heat sink 112 can be enlarged for the additional heat and size of stacked inductor 90’ with five cores. ALTERNATE EMBODIMENTS

[00087] Several other embodiments are contemplated by the inventors. For example many combinations and variations of the upper and lower cores are possible. Some of the graphite-adhesive laminate sheets may be deleted in some embodiments or may be cut to different shapes.

[00088] While an E core and a PQ core variation have been described, many variations of the magnetic core are possible, such as pot cores where the sides are extended to more completely surround bobbin 106, U-shaped cores that aremissing the second side leg, El cores where the upper core is an E-core and the lower core is rectangular or 1 shaped, RM cores, RS cores, DS cores, etc. Many extensions of E-cores and hybrid shapes and combinations are possible, such as EER cores, ETD cores, EP cores, EC cores, EFF cores, El cores, etc. The invention can be applied to any core shape, size, and core material because the graphite sheet is highly flexible.

[00089] While a core with a bobbin, a left leg, and a right leg has been shown, the core might have only one leg and the bobbin. For a magnetic core rod, first the graphite sheet is attached to the core rod. Then, some insulation tape is wrapped on top of the graphite sheet. Finally, the winding is wound around the rod. The legs might be extended toward each other and merge in the back to form a semicircle. The air gap could be present WO 2026 / 143753 PCT / CN2025 / 071070 10 in the bobbin and in one leg, but not in the other leg. The air gap could be located near thebottom, rather than halfway between the top and bottom. Other variations of the air gap are possible. There could be multiple air gaps or more than two core sections in the inductor.

[00090] The core may be made from material such as iron, iron oxides, ferrite, ferrite ceramics, silicon steel, amorphous steel, neodymium, powdered iron or other material. Ceramic may also be used. Examples of ferromagnetic core material include: Silicon steel, Powered iron, nickel-iron alloy, amorphous metal, etc. Examples of non-ferromagnetic core material include: Manganese ferrites, Non-magnetic ceramics, Polymers. The core may be made from ferromagnetic or from non-ferromagnetic materials. Ferrite is a generic name referring to the mixture of iron-oxide and other metal oxides. Other materials refers may include different mixture such as Amorphous.

[00091] The air gap in the magnetic core may have small spacers at comers to maintain a desired gap thickness. These spacers may be ceramic or othernon-conducting material. The air gap could be filled with a dielectric material or spacer that is not an electrical and magnetic conductor, such as PET tape or FR4. However, the air gap is normally filled with air.

[00092] The air gap may be in the middle of the inductor as shown, or may be offset from the center, such as nearer to the bottom of the inductor than to the top of the inductor. The upper core can be larger than the lower core when the air gap is shifted downward. The air gap could be at the bottom of the bobbin, and the lower core could be a bar rather than an E-shape, such as for an El core inductor.

[00093] While graphite sheets have been shown that are attached to all outer surfaces of the E-cores, graphite sheet 26 attached to the top surface of the upper core and graphite sheet 28 attached to the lower surface of the lower core could be deleted, since graphite sheets 26, 28 do not cross air gap 10. While graphite sheets 22, 24 have been shown that completely cover theouter surfaces of the left and right Jegs of the E-cores, the size of graphite sheets 22, 24 could be reduced to only partially cover the sides of the E-cores. Graphite sheets 22, 24 could be reduced in size to only cover air gap 10 and parts of the upper and lower E-core sides. Heat would still be transferred across air gap 10, although not as efficeitnly as when graphite sheets 22, 24 are larger in size, attaching to a larger surface area of the E-core sides. Graphite sheet 28 on the bottom could be deleted when good contact to heat sink 112 is otherwise provided, such as through connectors.

[00094] The thermally conductive particles can be carbon nanotubes, ceramic powder, Silicon carbide, Alumina, Boron oxide, Magnesium oxide, or other material that conducts heat. The adhesive provides a low contact resistance to the graphite sheet, allowing the graphite sheet to make better contact with the surface of the inductor core, providing better heat transfer.

[00095] The outer edges ofupper core 32 and lower core 34 can be rounded to allow the single large graphite sheet to better be fitted around the corners (Fig. 17). Sharp edges are more likely to break or weaken the graphite laminate. A coating can be applied to the inductor after the graphite sheets are attached to protect the WO 2026 / 143753 PCT / CN2025 / 071070 11 graphite laminates from scratching, abrasion, or damage. Microbumps (Fig. 15) in the adhesive can be added for better adhesion, or may be deleted for a simpler process. Many process methods and variations are possible.

[00096] While two graphite rings 52, 654 have been shown in Fig. 18 between front inductor 602 and inductor 30, there could be a single graphite sheet with adhesive on both sides.

[00097] While graphite sheets have been shown that are thermally conductive, other thermally conductive materials could be substituted for graphite. The conductive sheet can be any thermally conductive thin film such as copper, silicone, aluminum, etc. or amixture of graphite and other materials. However, they may not be as effective as the graphite sheet in improving the thermal perfonnance

[00098] Terms such as up, down, above, under, horizontal, vertical, inside, outside, are relative and depend on the viewpoint and are not meant to limit the invention to a particular perspective. Devices may be rotated so that vertical is horizontal and horizontal is vertical, so these terms are viewer dependent.

[00099] The background of the invention section may contain background information about the problem or environment of the invention rather than describe prior art by others. Thus inclusion of material in the background section is not an admission of prior art by the Applicant. [000100] Any methods or processes described herein are machine-implemented or computer-implemented and are intended to be performed by machine, computer, or other device and are not intended to be performed solely by humans without such machine assistance. Tangibleresults generated may include reports or other machine- generated displays on display devices such as computer monitors, projection devices, audio-generating devices, and related media devices, and may include hardcopy printouts that are also machine-generated. Computer control of other machines is another tangible result. [000101] Any advantages and benefits described may not apply to all embodiments of the invention. When the word "means" is recited in a claim element, Applicant intends for the claim element to fall under 35 USC Sect. 112, paragraph 6. Often a label of one or more words precedes the word "means". The word or words preceding the word "means" is a label intended to ease referencing of claim elements and is not intended to convey a structural limitation. Such means-plus-fimction claims are intended to cover not only the structures described herein for performing the function and their structural equivalents, but also equivalent strucmres. For example, although a nailand a screw have different structures, they are equivalent structures since they both perform the function of fastening. Claims that do not use the word “means” are not intended to fall under 35 USC Sect. 112, paragraph 6. Signals are typically electronic signals, but may be optical signals such as can be carried over a fiber optic line. [000102] The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. WO 2026 / 143753 PCT / CN2025 / 071070 12 Claims: 1. An inductor comprising: an upper core of magnetic material having a top portion, an upper leg extending downward from the top portion, and an upper bobbin extendingdownward from the top portion; a lower core of magnetic material having a bottom portion, a lower leg extending upward from the bottom portion, and a lower bobbin extending upward from the bottom portion; a bobbin air gap between the upper bobbin and the lower bobbin; a leg air gap between the upper leg and the lower leg; a graphite sheet laminate having an adhesive attached to an inner surface of a graphite sheet, the graphite sheet laminate being attached by the adhesive to an outer surface of the upper leg and being attached by the adhesive to an outer surface of the lower leg, the graphite sheet laminate straddling the leg air gap; and a wire that is wrapped multiple times around the upper bobbin and is wrapped multiple times around the lower bobbin; wherein heat generated at the upper bobbin is transferred through the top portion to the upper leg, and transferred to the graphite sheet laminate and across the leg air gap to the lower leg of the lower core, whereby the graphitesheet laminate transfers heat across the leg air gap from the upper core to the lower core. 2. The inductor of claim 1 wherein the outer surface of the upper leg is a surface facing away from the upper bobbin; wherein the outer surface of the lower leg is a surface facing away from the lower bobbin; wherein the graphite sheet laminate is attached to outer surfaces; wherein the graphite sheet laminate is not attached to an inner surface of the upper leg that faces the upper bobbin; wherein the graphite sheet laminate is not attached to an inner surface of the lower leg that faces the lower bobbin. 3. The inductor of claim 2 wherein the upper core further comprises a second upper leg extending downward from the top portion on a second end of the top portion that is opposite to a first end of the top portion having the upper leg extending downward; wherein the lower core further comprises a second lower leg extending upward from the bottom portion on a second end of the bottom portionthat is opposite to a first end of the bottom portion having the lower leg extending upward; wherein the upper bobbin is situated between the upper leg and the second upper leg; wherein the lower bobbin is situated between the lower leg and the second lower leg. 4. The inductor of claim 3 wherein the upper core has a cross-section that has an E-shape; wherein the lower core has a cross-section that has an E-shape; WO 2026 / 143753 PCT / CN2025 / 071070 13 wherein the inductor is an E-core inductor. 5. The inductor of claim 4 wherein the upper bobbin has a thickness that is less than a thickness of the upper leg; wherein the lower bobbin has a thickness that is less than a thickness of the lower leg. 6. The inductor of claim 5 wherein the inductor is a PQ-core inductor. 7. The inductor of claim 4 further comprising: a heat sink, attached to the lower core, the heat sink for dissipating heat to air forced over the heat sink; wherein heat from the lower core is transferred to the heat sink;wherein heat from the upper core is transferred through the graphite sheet laminate to the lower core and then to the heat sink. 8. The inductor of claim 7 further comprising: a bottom graphite sheet laminate having an adhesive attached to an inner surface of a graphite sheet, the bottom graphite sheet laminate being attached by the adhesive to an bottom surface of the bottom portion of the lower core, the bottom graphite sheet laminate for transferring heat from the lower core to the heat sink. 9. The inductor of claim 8 further comprising: a top graphite sheet laminate having an adhesive attached to an inner surface of a graphite sheet, the top graphite sheet laminate being attached by the adhesive to a top surface of the top portion of the upper core. 10. The inductor of claim 9 further comprising: a second leg air gap between the second upper leg and the second lower leg; a second graphite sheet laminate having an adhesive attached to an inner surface of a graphite sheet, thesecond graphite sheet laminate being attached by the adhesive to an outer surface of the second upper leg of the upper core, the second graphite sheet laminate also being attached by the adhesive to an outer surface of the second lower leg of the lower core; wherein the second graphite sheet laminate straddles the second leg air gap; wherein heat generated at the upper bobbin is transferred through the top portion to the second upper leg, and transferred to the second graphite sheet laminate and across the second leg air gap to the second lower leg of the lower core, whereby the second graphite sheet laminate also transfers heat across the second leg air gap from the upper core to the lower core. 11. The inductor of claim 10 further comprising: a front graphite sheet laminate having an adhesive attached to an inner surface of a graphite sheet having a ring shape, the front graphite sheet laminate being attached by the adhesive to front outer surfaces of the WO 2026 / 143753PCT / CN2025 / 071070 14 upper leg, the second upper leg, the top portion of the upper core, and the bottom portion of the lower core, the front graphite sheet laminate not being attached to the upper bobbin or to the lower bobbin; a back graphite sheet laminate having an adhesive attached to an inner surface of a graphite sheet having a ring shape, the back graphite sheet laminate being attached by the adhesive to back outer surfaces of the upper leg, the second upper leg, the top portion of the upper core, and the bottom portion of the lower core, the back graphite sheet laminate not being attached to the upper bobbin or to the lower bobbin. 12. The inductor of claim 11 wherein the adhesive is mixed with thermally conducting particles. 13. The inductor of claim 12 wherein the thermally conducting particles are carbon nanotubes. 14. The inductor of claim 11 further comprising: microbumps formed on the adhesive, the microbumps being thicker areas of the adhesive for improving adhesion ofthe graphite sheet to surfaces of the upper core or the lower core. 15. The inductor of claim 11 wherein the graphite sheet laminate, the top graphite sheet laminate, the second graphite sheet laminate, the bottom graphite sheet laminate, the front graphite sheet laminate, and the back graphite sheet laminate are each portions of a continuous graphite sheet laminate that is folded and cut to fit around the upper core and around the lower core. 16. The inductor of claim 15 wherein edges of the upper core and edges of the lower core are rounded to prevent sharp edges from wearing the continuous graphite sheet laminate at the edges of the upper core and at edges of the lower core. 17. The inductor of claim 11 wherein a second adhesive layer is also applied to an outer surface of the graphite sheet having the ring shape of the front graphite sheet laminate; further comprising: a front upper core having a same shape as the upper core, and having graphite sheet laminates attached to outersurfaces, the front upper core being attached by the second adhesive layer to the front graphite sheet laminate; a front lower core having a same shape as the lower core, and having graphite sheet laminates attached to outer surfaces, the front lower core being attached by the second adhesive layer to the front graphite sheet laminate; a front laminating ring of adhesive applied between the front upper core and the upper core, the front laminating ring of adhesive having the ring shape of the front graphite sheet laminate; a back upper core having a same shape as the upper core, and having graphite sheet laminates attached to outer surfaces, the back upper core being attached by the second back adhesive layer to the back graphite sheet laminate; WO 2026 / 143753 PCT / CN2025 / 071070 15 a back lower core having a same shape as the lower core, and having graphite sheet laminates attached to outer surfaces, the back lower core being attached by the second back adhesive layer to the backgraphite sheet laminate; a back laminating ring of adhesive applied between the back upper core and the upper core, the back laminating ring of adhesive having the ring shape of the back graphite sheet laminate. 18. The inductor of claim 17 wherein the wire is wrapped multiple times around the upper bobbin of the front upper core, the upper core, and the back upper core, wherein the wire is wrapped around the upper bobbin of the front upper core, the upper core, and the back upper core for each winding loop; wherein the wire is wrapped multiple times around the lower bobbin of the front lower core, the lower core, and the back lower core, wherein the wire is wrapped around the lower bobbin of the front lower core, the lower core, and the back lower core for each winding loop. 19. A thermally-enhanced inductor comprising: an upper core made of ferrite or ferromagnetic material that has a top bar, an upper bobbin, an upper left leg, and an upper right leg, wherein the top bar is in a topplane, and the upper bobbin, the upper left leg, and the upper right leg are in a second plane that is perpendicular to the top plane, wherein the upper bobbin is between the upper left leg and the upper right leg and separated from the upper left leg and the upper right leg by an upper winding void; an lower core made of ferrite or ferromagnetic material that has a bottom bar, a lower bobbin, a lower left leg, and a lower right leg, wherein the bottom bar is in a bottom plane that is parallel to the top plane, and the lower bobbin, the lower left leg, and the lower right leg are in the second plane, wherein the lower bobbin is between the lower left leg and the lower right leg and separated from the lower left leg and the lower right leg by a lower winding void; a left air gap between a bottom of the upper left leg and a top of the lower left leg; a right air gap between a bottom of the upper right leg and a top of the lower right leg; a bobbin air gap between a bottom of the upperbobbin and a top of the lower bobbin; a wire that is wound multiple times around the upper bobbin and is wound multiple times around the lower bobbin, the wire being wound in the upper winding void and in the lower winding void; a left thermally-conducting laminate sheet applied to an outer surface of the upper left leg and applied to an outer surface of the lower left leg, the outer surface being a surface not facing the upper winding void or the lower winding void; wherein the left thermally-conducting laminate sheet straddles the left air gap, the left thermally-conducting laminate sheet for transferring heat across the left air gap from the upper core to the lower core; and WO 2026 / 143753 PCT / CN2025 / 071070 16 a right thermally-conducting laminate sheet applied to an outer surface of the upper right leg and applied to an outer surface of the lower right leg, the outer surface being a surface not facing the upper winding void or the lower winding void; wherein the rightthermally-conducting laminate sheet straddles the right air gap, the right thermally-conducting laminate sheet for transferring heat across the right air gap from the upper core to the lower core; wherein each thermally-conducting laminate sheet has an adhesive applied to a surface of a thermally- conducting layer that faces the upper core or the lower core, the adhesive for lowering contact resistance of the thermally-conducting layer to the ferrite or ferromagnetic material of the upper core or of the lower core; whereby heat transfer from the upper core to the lower core across the left air gap is increased by the left thermally-conducting laminate sheet, and heat transfer across the right air gap is increased by the right thermally-conducting laminate sheet. 20. A thermally-enhanced stacked inductor comprising: a plurality of cores, each core comprising: an upper core made of ferrite or ferromagnetic material that has a top bar, an upper bobbin, an upper left leg, and an upperright leg, wherein the top bar is in a top plane, and the upper bobbin, the upper left leg, and the upper right leg are in a second plane that is perpendicular to the top plane, wherein the upper bobbin is between the upper left leg and the upper right leg and separated from the upper left leg and the upper right leg by an upper winding void; an lower core made of ferrite or ferromagnetic material that has a bottom bar, a lower bobbin, a lower left leg, and a lower right leg, wherein the bottom bar is in a bottom plane that is parallel to the top plane, and the lower bobbin, the lower left leg, and the lower right leg are in the second plane, wherein the lower bobbin is between the lower left leg and the lower right leg and separated from the lower left leg and the lower right leg by a lower winding void; a left air gap between a bottom of the upper left leg and a top of the lower left leg; a right air gap between a bottom of the upper right leg and a top of the lower right leg; abobbin air gap between a bottom of the upper bobbin and a top of the lower bobbin; a wire that is wound multiple times around the upper bobbin and is wound multiple times around the lower bobbin, the wire being wound in the upper winding void and in the lower winding void; a left graphite laminate sheet applied to an outer surface of the upper left leg and applied to an outer surface of the lower left leg, the outer surface being a surface not facing the upper winding void or the lower winding void; wherein the left graphite laminate sheet straddles the left air gap, the left graphite laminate sheet for transferring heat across the left air gap from the upper core to the lower core; and WO 2026 / 143753 PCT / CN2025 / 071070 17 a right graphite laminate sheet applied to an outer surface of the upper right leg and applied to an outer surface of the lower right leg, the outer surface being a surface not facing the upper winding void or the lower winding void; wherein the right graphitelaminate sheet straddles the right air gap, the right graphite laminate sheet for transferring heat across the right air gap from the upper core to the lower core; wherein each graphite laminate sheet has an adhesive applied to a surface of a graphite layer that faces the upper core or the lower core, the adhesive for lowering contact resistance of the graphite layer to the ferrite or ferromagnetic material of the upper core or of the lower core; between an adjacent pair of cores in the plurality of cores, a front graphite laminate sheet having the adhesive on both surfaces of the graphite layer, the front graphite laminate sheet having a ring shape; wherein the front graphite laminate sheet is attached by the adhesive to front outer surfaces of the upper left leg, the upper right leg, the top bar of the upper core, and the lower left leg, the lower right leg, and the bottom bar of the lower core of a front-facing core of the adjacent pair of cores; wherein the front graphite laminatesheet is attached by the adhesive to back outer surfaces of the upper left leg, the upper right leg, the top bar of the upper core, and the lower left leg, the lower right leg, and the bottom bar of the lower core of a back-facing core of the adjacent pair of cores; wherein the front graphite laminate sheet is not attached to the upper bobbin or to the lower bobbin. 10 6 WO 2026 / 143753 PCT / CN2025 / 071070 I— tr< cc < (T O cc CL 1 / 17 12 0 WO 2026 / 143753 PCT / CN2025 / 071070 2 / 17 PR IO R A R T 10 6 WO 2026 / 143753 PCT / CN2025 / 071070 3 / 17 PR IO R A R T WO 2026 / 143753 PCT / CN2025 / 071070 4 / 17 FI G . 8 WO 2026 / 143753 PCT / CN2025 / 071070 5 / 17 IG . 9 WO 2026 / 143753 PCT / CN2025 / 071070 6 / 17 WO 2026 / 143753 PCT / CN2025 / 071070 7 / 17 WO 2026 / 143753 PCT / CN2025 / 071070 8 / 17 10 2 WO 2026 / 143753 PCT / CN2025 / 071070 9 / 17 WO 2026 / 143753 PCT / CN2025 / 071070 10 / 17 WO 2026 / 143753 PCT / CN2025 / 071070 < CD 0 11 / 17 24 <4 A1 [2 4m FIG. 16B WO 2026 / 143753 PCT / CN2025 / 071070 12 / 17 75 2 7 53 WO 2026 / 143753 PCT / CN2025 / 071070 13 / 17 FI G. 1 8 WO 2026 / 143753 PCT / CN2025 / 071070 14 / 17 60 2 WO 2026 / 143753 PCT / CN2025 / 071070 15 / 17 FI G . 2 0 WO 2026 / 143753 PCT / CN2025 / 071070 16 / 17 WO 2026 / 143753 PCT / CN2025 / 071070 17 / 17 INTERNATIONAL SEARCH REPORT International application No. PCT / CN2025 / 071070 A. CLASSIFICATION OF SUBJECT MATTER H01F27 / 24(2006.01)i ; H01F27 / 00(2006.01)i According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC: H01F Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) CNTXT,ENTXT,ENTXTC,DWPI,CNKI:inductor,transformer,gap,bobbin,graphite,heat, cool C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of therelevant passages Relevant to claim No. Y CN 112204685 A (GENERAL ELECTRIC COMPANY) 08 January 2021 (2021-01-08) paragraphs 26-90,Figures 1-10 1-20 Y CN 111988958 A (LU HAO) 24 November 2020 (2020-11-24) paragraphs 31-44 , Figures 1-9 1-20 A CN 207165345 U (JIANGSU RUISHUN SUPERFINE COPPER WIRE TECHNOLOGY COLLABORATIVE INNOVATION CO., LTD.) 30 March 2018 (2018-03-30) full text 1-20 A WO 9217892 Al (MOTOROLA LIGHTING INC) 15 October 1992 (1992-10-15) full text 1-20 | | Further documents are listed in the continuation of Box C. | / | See patent family annex. * Special categories of cited documents: “T” later document published after the international filing date or priority “A” document defining the general state of the art which is not considered date and not in conflict with the application but cited to understand the to be of particular relevance principle or theory underlying the invention “D” document cited by the applicant in the international application “X” document of particularrelevance; the claimed invention cannot be “E” earUer appUcation or patent but pubHshed on or after the international considered novel or cannot be considered to involve an inventive step filing date when the document is taken alone “L” document which may throw doubts on priority claim(s) or which is “Y” document of particular relevance; the claimed invention cannot be cited to establish the publication date of another citation or other considered to involve an inventive step when the document is special reason (as specified) combined with one or more other such documents, such combination “O” document refening to an oral disclosure, use, exhibition or other being obvious to a person skilled in the art means document member of the same patent family “P” document published prior to the international filing date but later than the priority date claimed Date of the actual completion of the international search 11 July 2025 Date of mailing of the international search report 14 July 2025Name and mailing address of the ISA / CN CHINA NATIONAL INTELLECTUAL PROPERTY ADMINISTRATION 6, Xitucheng Rd., Jimen Bridge, Haidian District, Beijing 100088, China Authorized officer LI,Jing Telephone No. (+86) 62411756 Form PCT / ISA / 210 (second sheet) (July 2022) INTERNATIONAL SEARCH REPORT Information on patent family members International application No. PCT / CN2025 / 071070 Patent document cited in search report Publication date (day / month / year) Patent family member(s) Fiblication date (day / month / year) CN 112204685 A 08 January 2021 None CN 111988958 A 24 November 2020 None CN 207165345 U 30 March 2018 None WO 9217892 Al 15 October 1992 None Form PCT / ISA / 210 (patent family annex) (July 2022) (19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number CN 120019454 A (43) Application Publication Date 2025. 05. 16 (21) Application Number 202580000128.4 (22) Application Date 2025.01.07 (30) Priority Data 19 / 005,044 2024.12.30 US (85) PCT International Application Entering National Phase Date 2025.02.06 (51) Int.CI. H01F 27 / 22 (2006.01) HO1F 27 / 24 (2006.01) HO1F 27 / 26(2006.01) H01F 27 / 30(2006.01) H01F 27 / 34(2006.01) (86)Application data for PCT international application: PCT / CN2025 / 071070 2025.01.07 (71) Applicant: Hong Kong Applied Science and Technology Research Institute Limited Address: 5 / F, Optoelectronics Centre, 2 Science Avenue East, Hong Kong Science Park, Shatin, New Territories, Hong Kong (72) Inventors: Lam Pak-di, Poon Ngo Wai-lu, Li Tianhe (74) Patent Agency: Shenzhen Xinchuangyou Intellectual Property Agency Co., Ltd. 44223 Patent Attorney: Xie Linhong Claims: 4 pages Specification: 8 pages Drawings: 11 pages (54) Invention Title: Magnetic Element Using Graphite Laminate to Enhance Heat Transfer and Dissipation (57) Abstract: The inductor core has an air gap that prevents heat from being transferred from the upper core to the lower core through the air gap. The core cross-section is E-shaped, with wires wound on the central post or frame, and no wires wound on the left and right legs. An adhesive is applied to a graphite sheet, which is then attached to the outside of the left and right legs. A graphite adhesive laminate spans the air gap, allowing heat to be transferred through the air gap. Graphite sheets are not attached to the skeleton; thermally conductive particles, such as carbon nanotubes, can be added to the adhesive. Multiple inductors can be stacked laterally. A heat sink connected to the lower core dissipates heat generated by the upper core through heat conduction across the graphite sheets spanning the air gap. 600 VSSI 0 0 2 I 3 CN 120019454 A Claims 1 / 4 page 1 • An inductor comprising: an upper magnetic core of magnetic material having a top, an upper leg extending downward from the top, and an upper frame extending downward from the top; a lower magnetic core of magnetic material having a bottom, a lower leg extending upward from the bottom, and a lower frame extending upward from the bottom; a frame air gap between the upper frame and the lower frame; a leg air gap between the upper leg and the lower leg; a graphite sheet laminate having an adhesive adhered to an inner surface of a graphite sheet, the graphite sheet laminate being adhered to an outer surface of the upper leg by the adhesive and to an outer surface of the lower leg by the adhesive, the graphite sheet laminate spanning the leg air gap; and a conductor wound multiple times on the upper frame and multiple times on the lower frame. The heat generated on the upper frame is transferred through the top to the upper leg, and then to the graphite laminate, passing through the leg air gap to the lower leg of the lower magnetic core. Thus, the graphite laminate transfers heat from the upper magnetic core to the lower magnetic core through the leg air gap. 2. The inductor according to claim 1, wherein the outer surface of the upper leg is a surface facing away from the upper frame; wherein the outer surface of the lower leg is a surface facing away from the lower frame; wherein the graphite laminate is attached to the outer surface; wherein the graphite laminate is not attached to the inner surface of the upper leg facing the upper frame.3. The inductor of claim 2, wherein the graphite sheet laminate is not attached to the inner surface of the lower support facing the lower frame. 4. The inductor of claim 3, wherein the upper core further includes a second upper support extending downward from the top, the second upper support being located at a second end of the top, the second end of the top being opposite to a first end of the top, the first end having the downwardly extending upper support; wherein the lower core further includes a second lower support extending upward from the bottom, the second lower support being located at a second end of the bottom, the second end of the bottom being opposite to a first end of the bottom, the first end of the bottom having the upwardly extending lower support; wherein the upper frame is located between the upper support and the second upper support; wherein the lower frame is located between the lower support and the second lower support. 5. The inductor of claim 3, wherein the upper core has an E-shaped cross-section; wherein the lower core has an E-shaped cross-section; wherein the inductor is an E-type core inductor. 5. The inductor of claim 4, wherein the thickness of the upper frame is less than the thickness of the upper leg; wherein the thickness of the lower frame is less than the thickness of the lower leg. 6. The inductor of claim 5, wherein the inductor is a PQ core inductor. 7. The inductor of claim 4, further comprising: a heat sink attached to the lower core, the heat sink being used for forced heat dissipation into the air surrounding the heat sink; wherein heat from the lower core is transferred to the heat sink; wherein heat from the upper core is transferred through the graphite sheet laminate to the lower core and then to the heat sink. 8. The inductor of claim 7, further comprising: a bottom graphite sheet laminate having an adhesive adhered to the inner surface of the graphite sheet, the bottom graphite sheet laminate being adhered to the bottom surface of the lower core by the adhesive, the bottom graphite sheet laminate being used for transferring heat from the lower core to the heat sink. 9. The inductor of claim 8, further comprising: a top graphite sheet laminate having an adhesive adhered to an inner surface of a graphite sheet, the top graphite sheet laminate being attached to a top surface of the top of the upper magnetic core via the adhesive. 10. The inductor of claim 9, further comprising: a second leg air gap located between the second upper leg and the second lower leg; a second graphite sheet laminate having an adhesive adhered to an inner surface of a graphite sheet, the second graphite sheet laminate being attached to an outer surface of the second upper leg of the upper magnetic core via the adhesive, the second graphite sheet laminate also being attached to an outer surface of the second lower leg of the lower magnetic core via the adhesive; wherein the second graphite sheet laminate spans the second leg air gap;The heat generated at the upper frame is transferred through the top to the second upper support leg, and then to the second graphite sheet laminate. It is also transferred through the air gap of the second support leg to the second lower support leg of the lower magnetic core. Therefore, the second graphite sheet laminate also transfers heat from the upper magnetic core through the air gap of the second support leg to the lower magnetic core. 11. The inductor of claim 10, further comprising: a front graphite laminate having an adhesive attached to the inner surface of an annular graphite sheet, the front graphite laminate being attached to the front outer surface of the upper leg, the second upper leg, the top of the upper magnetic core, and the bottom of the lower magnetic core via the adhesive, the front graphite laminate not being attached to the upper frame or the lower frame; and a rear graphite laminate having an adhesive attached to the inner surface of an annular graphite sheet, the rear graphite laminate being attached to the rear outer surface of the upper leg, the second upper leg, the top of the upper magnetic core, and the bottom of the lower magnetic core via the adhesive, the rear graphite laminate not being attached to the upper frame or the lower frame. 12. The inductor of claim 11, wherein the adhesive is mixed with thermally conductive particles. 13. The inductor of claim 12, wherein the thermally conductive particles are carbon nanotubes. 14. The inductor of claim 11, further comprising: microbumps formed on the adhesive, the microbumps being thicker areas of the adhesive for improving adhesion between the graphite sheet and the surface of the upper or lower magnetic core. 15. The inductor of claim 11, wherein the graphite laminate, the top graphite laminate, the second graphite laminate, the bottom graphite laminate, the front graphite laminate, and the rear graphite laminate are all part of a continuous graphite laminate, which is folded and cut to fit around the upper and lower magnetic cores. 16. The inductor of claim 15, wherein the edges of the upper and lower magnetic cores are rounded to prevent sharp edges from abrading the continuous graphite laminate at the edges of the upper and lower magnetic cores. 17. The inductor of claim 11, wherein a second adhesive layer is further applied to the outer surface of the annular graphite sheet of the front graphite laminate; further comprising: a front upper magnetic core having the same shape as the upper magnetic core, the outer surface of which is attached with a graphite laminate, the front upper magnetic core being attached to the front graphite laminate via the second adhesive layer; a front lower magnetic core having the same shape as the lower magnetic core, the outer surface of which is attached with a graphite laminate, the front lower magnetic core being attached to the front graphite laminate via the second adhesive layer; a front adhesive laminate ring applied between the front upper magnetic core and the upper magnetic core, the front adhesive laminate ring having the annular shape of the front graphite laminate;The upper rear magnetic core has the same shape as the upper magnetic core, and a graphite sheet laminate is attached to its outer surface. The upper rear magnetic core is attached to the graphite sheet laminate via a second post-adhesive layer. The lower rear magnetic core has the same shape as the lower magnetic core, and a graphite sheet laminate is attached to its outer surface. The lower rear magnetic core is attached to the graphite sheet laminate via a second post-adhesive layer. A post-adhesive laminate ring is applied between the upper rear magnetic core and the upper magnetic core. The post-adhesive laminate ring has the annular shape of the graphite sheet laminate. 18. The inductor of claim 17, wherein the conductor is wound multiple times on the upper frame of the front upper magnetic core, the upper magnetic core, and the rear upper magnetic core, wherein for each winding loop, the conductor is wound on the upper frame of the front upper magnetic core, the upper magnetic core, and the rear upper magnetic core; wherein the conductor is wound multiple times on the lower frame of the front lower magnetic core, the lower magnetic core, and the rear lower magnetic core, wherein for each winding loop, the conductor is wound on the lower frame of the front lower magnetic core, the lower magnetic core, and the rear lower magnetic core. 19. An inductor with improved thermal performance, comprising: an upper magnetic core made of ferrite or ferromagnetic material, having a top crossbar, an upper frame, an upper left support, and an upper right support, wherein the upper crossbar is located in a top plane, the upper frame, the upper left support, and the upper right support are located in a second plane perpendicular to the top plane, wherein the upper frame is located between the upper left support and the upper right support and is separated from the upper left support and the upper right support by an upper winding gap; and a lower magnetic core made of ferrite or ferromagnetic material, having a bottom crossbar, a lower frame, a lower left support, and a lower right support, wherein the bottom crossbar is located in a bottom plane parallel to the top plane, the lower frame, the lower left support, and the lower right support are located in the second plane, wherein the lower frame is located between the lower left support and the lower right support and is separated from the lower left support and the lower right support by a lower winding gap; A left air gap is located between the bottom of the upper left support leg and the top of the lower left support leg; a right air gap is located between the bottom of the upper right support leg and the top of the lower right support leg; a frame air gap is located between the bottom of the upper frame and the top of the lower frame; a wire is wound multiple times around the upper frame and multiple times around the lower frame, the wire being wound in the upper winding gap and the lower winding gap; a left heat-conducting laminate is applied to the outer surface of the upper left support leg and the outer surface of the lower left support leg, the outer surface not facing the upper winding gap or the lower winding gap; wherein the left heat-conducting laminate spans the left air gap, the left heat-conducting laminate being used to transfer heat through the left air gap from the upper magnetic core to the lower magnetic core; and a right heat-conducting laminate is applied to the outer surface of the upper right support leg and the outer surface of the lower right support leg, the outer surface not facing the upper winding gap or the lower winding gap;The right heat-conducting laminate spans the right air gap and is used to transfer heat through the right air gap from the upper magnetic core to the lower magnetic core. Each heat-conducting laminate has an adhesive applied to the surface of the heat-conducting layer facing the upper or lower magnetic core. The adhesive is used to reduce the contact resistance between the heat-conducting layer and the ferrite or ferromagnetic material of the upper or lower magnetic core. Thus, the left heat-conducting laminate increases heat transfer through the left air gap from the upper magnetic core to the lower magnetic core, and the right heat-conducting laminate increases heat transfer through the right air gap. 20. A multilayer inductor with improved thermal performance, comprising a plurality of magnetic cores, each core comprising: an upper core made of ferrite or ferromagnetic material having a top crossbar, an upper frame, an upper left support, and an upper right support, wherein the top crossbar is located in a top plane, the upper frame, the upper left support, and the upper right support are located in a second plane perpendicular to the top plane, wherein the upper frame is located between the upper left support and the upper right support and is separated from the upper left support and the upper right support by an upper winding gap; and a lower core made of ferrite or ferromagnetic material having a bottom crossbar, a lower frame, a lower left support, and a lower right support, wherein the bottom crossbar is located in a bottom plane parallel to the top plane, the lower frame, the lower left support, and the lower right support are located in the second plane, wherein the lower frame is located between the lower left support and the lower right support and is separated from the lower left support and the lower right support by a lower winding gap; A left air gap is located between the bottom of the upper left support leg and the top of the lower left support leg; a right air gap is located between the bottom of the upper right support leg and the top of the lower right support leg; a frame air gap is located between the bottom of the upper frame and the top of the lower frame; a wire is wound multiple times around the upper frame and multiple times around the lower frame, the wire being wound in the upper winding gap and the lower winding gap; a left graphite laminate is applied to the outer surface of the upper left support leg and the outer surface of the lower left support leg, the outer surface not facing the upper winding gap or the lower winding gap; wherein the left graphite laminate spans the left air gap, the left graphite laminate is used to transfer heat from the upper magnetic core to the lower magnetic core; and a right graphite laminate is applied to the outer surface of the upper right support leg and the outer surface of the lower right support leg, the outer surface not facing the upper winding gap or the lower winding gap; The right graphite laminate spans the right air gap and is used to transfer heat from the upper magnetic core to the lower magnetic core. Each graphite laminate contains an adhesive, which is applied to the graphite layer facing either the upper or lower magnetic core.On the surface of the magnetic core, an adhesive is used to reduce the contact resistance between the graphite layer and the ferrite or ferromagnetic material of the upper or lower magnetic core; between adjacent pairs of magnetic cores, a front graphite laminate has adhesive on both surfaces of the graphite layer, and the front graphite laminate is annular; wherein, the front graphite laminate is attached by adhesive to the front outer surface of the upper left, upper right, and top crossbar of the upper magnetic core and the lower left, lower right, and bottom crossbar of the lower magnetic core in the front magnetic core of the adjacent pair of magnetic cores; wherein, the front graphite laminate is attached by adhesive to the rear outer surface of the upper left, upper right, and top crossbar of the upper magnetic core and the lower left, lower right, and bottom crossbar of the lower magnetic core in the back magnetic core of the adjacent pair of magnetic cores; wherein, the front graphite laminate is not attached to the upper or lower frame. 5 CN 120019454 A Specification 1 / Page Magnetic Components Using Graphite Laminates Can Enhance Heat Transfer and Dissipation [Technical Field]

[0001] This invention relates to inductors with magnetic cores, and particularly to heat transfer in the air gap of an inductor core. [Background Art]

[0002] Magnetic components such as inductors and transformers are commonly used in power converters, such as switched-mode power supplies (SMPS).

[0003] Figure 1 shows an inductor with a magnetic core. A long insulating wire is wound around the core of the inductor. A transformer is an inductor with two or more windings on the core, such as a primary winding and a secondary winding, which are electrically isolated but magnetically coupled. Traditionally, the core is made of iron or ferrite and is cylindrical in shape.

[0004] A more advanced inductor has an E-shaped core or E-type core. In Figure 1, the wire 120 is wound around the central post or frame 106 of the E-type magnetic core. The E-type magnetic core has an upper core 104 and a lower core 108, each with a cross-section resembling the letter E. For example, the cross-section of the upper core 104 looks like the letter E rotated downwards, while the cross-section of the lower core 108 looks like the letter E rotated upwards (Figure 4).

[0005] The frame 106 is located at the center of the E-type cross-section, while the sides of the upper core 104 and the lower core 108 partially surround the wire 120. In many different E-type magnetic cores, the frame 106 can be square or circular. The wire 120 is easier to wound around a circular frame 106 than a square frame 106. E-type magnetic core inductors offer lower core losses even at higher temperatures; higher efficiency due to better magnetic coupling; lower manufacturing costs; a compact design that overcomes space constraints; and easier assembly for prototyping and testing.

[0006] The upper core 104 and the lower core 108 are separated by an air gap 100. An air gap of 100 can prevent saturation and allow for higher magnetic flux and energy storage.

[0007] Figure 2 shows an inductor core. The wire 120 has been removed from Figure 2 to show the upper core 104 and lower core 108 in more detail. The bobbin 106 is not rectangular but cylindrical to better wind the wire 120 into a coil shape. Air gaps 100 exist on both sides of the bobbin 106 and the upper and lower cores 104.

[0008] Figure 3 shows an inductor mounted on a heatsink. The heatsink 112 can be directly connected to the bottom of the lower core 108 as shown, or indirectly connected to the bottom of the lower core 108 via a printed circuit board (PCB) with metal heat pipes or other heat-conducting components to conduct heat from the lower core 108 to the heatsink 112.

[0009] Note that the upper core 104 is not connected to any heatsink. High-density power converters are typically narrow, making it impossible to mount heatsinks on both the upper and lower cores of the inductor.

[0010] Figure 4 is a cross-section of the inductor of Figures 1-3. The upper magnetic core 104 is E-shaped and separated from the E-shaped lower magnetic core 108 by an air gap 100. The frame 106 is also separated by the air gap 100. A wire 120 (not shown) is wound around the frame 106 and located in the gap 116 between the frame 106 and the upper and lower magnetic cores 104 and 108.

[0011] A heat sink 112 is connected to the bottom of the lower magnetic core 108. The heat sink 112 can dissipate heat from the lower magnetic core 108. Airflow can be forced through the heat sink fins on the lower surface of the heat sink 112 to enhance the heat dissipation effect. However, since the air gap 100 hinders heat transfer, the heat generated in the upper magnetic core 104 cannot be easily transferred to the heat sink 112.

[0012] Figure 5 shows the heat transfer situation inside the inductor of Figures 1-4. When current flows through the wire 120, the wire 120 heats up due to the resistance in the long wire. Furthermore, when alternating current (AC) is applied to conductor 120, the magnetic flux reverses as the direction of the AC current changes (see page 2 / 8 of the specification). These magnetic flux reversals may exhibit hysteresis, generating eddy currents within the upper core 104 and lower core 108. The heat generated by these eddy currents is greatest in the frame 106, where the magnetic flux is most concentrated.

[0013] The heat generated by the resistance in conductor 120 and the magnetic flux reversal in frame 106 causes the temperatures of the upper core 104 and lower core 108 to rise. However, the heat in the lower core 108 can be transferred to the heat sink 112, thereby reducing the temperature of the lower core 108. However, the air gap 100 prevents or significantly reduces heat transfer from the upper core 104 to the lower core 108. Therefore, the temperature of the upper core 104 may be higher than that of the lower core 108.

[0014] The temperature of the upper magnetic core 104 may be 40 degrees higher than that of the lower magnetic core 108. This higher temperature in the upper magnetic core 104 is undesirable because overheating can lead to malfunctions and shorten the lifespan of the inductor and other nearby components.

[0015] There is a need for an inductor with better heat transfer performance. There is a need for an inductor that enhances heat transfer through the air gap between the upper and lower E-type magnetic cores. There is a need for an air gap inductor with a laminated coating to transfer heat through the air gap. [Figure Descriptions]

[0016] Figure 1 shows an inductor with a magnetic core.

[0017] Figure 2 shows the inductor core.

[0018] Figure 3 shows an inductor mounted on a heat sink.

[0019] Figure 4 is a cross-section of the inductor of Figures 1-3.

[0020] Figure 5 shows the heat conduction within the inductor of Figures 1-4.

[0021] Figure 6 shows an E-type magnetic core inductor with a heat-conducting laminate attached to the outer surface of the core.

[0022] Figure 7 shows an E-type core inductor with a graphite adhesive laminate attached to the outer surface of the E-type core.

[0023] Figure 8 is a cross-section of an E-core inductor with graphite sheets attached to its outer surface to transfer heat in the air gap.

[0024] Figure 9 highlights the heat transfer of the graphite sheets in the air gap.

[0025] Figure 10 shows graphite laminates also attached to the front and rear surfaces of the E-core side feet.

[0026] Figure 11 shows graphite laminates attached to all outer surfaces of the E-core.

[0027] Figure 12 shows more details of the graphite laminate.

[0028] Figure 13 shows the graphene layer in the graphite.

[0029] Figure 14 shows the process of forming an adhesive layer on a graphite sheet to form a graphite laminate.

[0030] Figure 15 shows the graphite laminate in more detail.

[0031] Figures 16A-16B® show the attachment of a single graphite laminate to the four outer sides of the inductor.

[0032] Figure 17 highlights the case where a single large graphite plate is attached to the upper magnetic core 32 and the lower magnetic core 34.

[0033] Figure 18 shows three inductor cores laminated together with laminated graphite plates.

[0034] Figure 19 shows a stacked inductor with graphite rings between the inductor cores.

[0035] Figure 20 shows a stacked inductor connected to a heat sink.

[0036] Figures 21A-21BS show different core types.

[0037] Figure 22 shows a stacked inductor with five cores.

Detailed Description

[0038] The present invention relates to improvements in inductors. The following description is intended to enable those skilled in the art to make and use the invention in the context of specific applications and their requirements. Various modifications to preferred embodiments will be apparent to those skilled in the art, and the general principles defined herein may also be applied to other embodiments. Therefore, this invention is not intended to be limited to the specific embodiments shown and described, but is to be given the broadest scope conforming to the principles and novel features disclosed herein.

[0039] Figure 6 shows an E-type magnetic core inductor with a heat-conducting laminate attached to the outer surface of its core. Inductor 30It is an E-type magnetic core inductor, with its upper and lower magnetic cores separated by an air gap 10. A long wire (not shown) is wound around the frame 106 of the inductor 30. The side legs of the upper and lower magnetic cores partially surround the coil wound on the frame 106.

[0040] Graphite sheets 22, 24, 26, and 28 are laminates, each laminate having a graphite layer and an adhesive layer laminated together. The adhesive layer of graphite sheet 22 is pressed onto the outer surface of the right side leg of the upper and lower magnetic cores. The adhesive layer of graphite sheet 24 is pressed onto the outer surface of the left side leg of the upper and lower magnetic cores. The adhesive layer of graphite sheet 26 is pressed onto the outer top surface of the upper magnetic core, while the adhesive layer of graphite sheet 28 is pressed onto the outer top surface of the lower magnetic core.

[0041] Graphite sheet 22 spans the air gap 10, which separates the right legs of the upper and lower magnetic cores. Similarly, graphite sheet 24 spans the air gap 10, which separates the left feet of the upper and lower magnetic cores. The adhesive layer ensures that the graphite layer of the laminate adheres to the outer surface of the magnetic core.

[0042] Figure 7 shows an E-core inductor with a graphite adhesive laminate attached to the outer surface of the E-core. Graphite sheets 22, 24, 26, and 28 are attached to the four outer surfaces of the upper and lower E-cores of the inductor 30, respectively. Graphite has good thermal conductivity and can conduct heat from the upper core through the air gap 10 to the lower core. Graphite sheet 22 passes through the air gap 10 on the right side of the E-core, while graphite sheet 24 passes through the air gap 10 on the left side of the E-core.

[0043] Figure 8 is a cross-sectional view of an E-core inductor with graphite sheets attached to its outer surface for heat transfer between air gaps. The upper magnetic core 32 and the lower magnetic core 34 are E-type ferrite cores with a long wire (not shown) wound around their skeleton. Graphite sheet 22 is attached to the outer surface of the right foot of the upper magnetic core 32 and the lower magnetic core 34, so that graphite sheet 22 covers the right side of the air gap 10. Graphite sheet 24 is attached to the outer surface of the left foot of the upper magnetic core 32 and the lower magnetic core 34, so that graphite sheet 24 covers the left side of the air gap 10.

[0044] Graphite sheet 26 is attached to the top surface of the upper magnetic core 32 by adhesive, while graphite sheet 28 is attached to the bottom surface of the lower magnetic core 34 by adhesive. Heat sink 122 can be attached to graphite sheet 28 by another layer of adhesive, or simply pressed together and secured in place by connectors or fasteners (e.g., screws or bolts).

[0045] Figure 9 highlights the thermal conduction of the graphite sheets in the air gap. During operation, the frames of the upper core 32 and lower core 34 heat up due to the eddy currents in the ferrite core and the resistance heating of the long wires wound on the frame. The heat from the frame flows outward through the upper core 32, reaching the left and right legs of the upper core 32. Some of the heat from the frame is also conducted to the graphite sheet 26, and then flows along the top of the inductor to the graphite sheets 22 and 24 on both sides.

[0046] Some of the heat conducted along the top graphite sheet 26 and more heat conducted from the left leg of the upper core 32 are conducted away.The heat from the left graphite sheet 24 is conducted downwards through the air gap 10 to the left foot of the lower magnetic core 34, or to the bottom graphite sheet 28 and the heat sink 112. Therefore, the heat from the upper magnetic core 32 frame is conducted to the heat sink 112 through the graphite sheets 26, 24, and 28, which dissipate the heat into the air.

[0047] Other heat conducted along the top graphite sheet 26, as well as more heat conducted from the right foot of the upper magnetic core 32, is conducted to the right graphite sheet 22. The heat from the right graphite sheet 22 is conducted downwards through the air gap 10 to the right foot of the lower magnetic core 34, or to the bottom graphite sheet 28 and the heat sink 112. Therefore, the heat from the upper magnetic core 32 frame is also conducted to the heat sink 112 through the graphite sheets 26, 22, and 28, which dissipate the heat into the air.

[0048] Graphite sheets 22 and 24 act as bridges in the air gap 10, allowing heat to be conducted from the upper core 32 to the lower core 34. This results in a more uniform heat distribution within the inductor, reducing hot spots and thermal failures. The heat sink 112 dissipates this heat when a fan forces air through the fins on the heat sink 112.

[0049] Figure 10 shows that graphite laminates are also attached to the front and rear surfaces of the E-type core side feet. The front graphite sheet 52 has a back adhesive layer that is pressed against the front of the upper core 32 and the lower core 34. The rear graphite sheet 54 has a front adhesive layer that is pressed against the back of the upper core 32 and the lower core 34. The front and rear graphite sheets 52 are not pressed against the frame.

[0050] Figure 11 shows all the outer surfaces of the graphite laminates attached to the E-type core. Although the graphite laminate is not attached to the skeleton wound with long wires, graphite sheets 22, 24, and 26 are attached to the outer top and side surfaces of the upper magnetic core 32, while graphite sheets 22, 24, and 28 are attached to the outer bottom and side surfaces of the lower magnetic core 34. Graphite sheets 22 and 24 span the air gap.

[0051] The front graphite sheet 52 is a square ring attached to the front surfaces of the upper magnetic core 32 and the lower magnetic core 34. The rear graphite sheet 54 is a square ring attached to the rear or back surface of the upper magnetic core 32 and the lower magnetic core 34.

[0052] Figure 12 shows the graphite laminate in more detail. Graphite sheet 22 is a laminate having a graphite layer 70 and an adhesive layer 74. The adhesive layer 74 may be acrylic tape attached to the graphite layer 70. The thermal conductivity of the adhesive layer 74 may be enhanced by adding thermally conductive particles 76 to the adhesive layer 74. For example, the thermally conductive particles 76 may be carbon nanotubes.

[0053] Figure 13 shows the graphene layers in graphite. Graphite contains multiple layers of graphene 102, which are stacked together like a sheet of paper. However, the stacks of graphene 102 may have different orientations. The carbon atoms of graphene 102 are in a planar hexagonal pattern. Graphite has good thermal and electrical conductivity.

[0054] Ferrite cores have good magnetic properties but are electrically insulating. If conductive graphite layers 22, 24 are placed within or between air gaps, the magnetic flux through the air gaps will be affected, thereby reducing the effective saturation. Eddy currents may be generated on the conductors, leading to higher power losses. When the graphite layers 22, 24 are located around or outside the air gaps, the magnetic field is less disturbed, and eddy current losses are avoided. Since the core is usually made of a non-conductive material, such as ferrite, electrical conductors such as graphite layers 22, 24 crossing the air gap 10 will not cause any electrical short circuits or problems.

[0055] Figure 14 shows the process of forming an adhesive layer on a graphite sheet to form a graphite laminate. The graphite layer 70 can be a commercially available graphite sheet. As the graphite layer 70 rolls by a conveyor belt or the like, a nozzle n sprays a liquid adhesive onto the upper surface of the graphite layer 70, forming an adhesive layer 74 on the upper surface of the graphite layer 70. Before the mixture is fed into nozzle 77, the thermally conductive particles 76 can be mixed with the liquid adhesive. Mechanical mixing can be supplemented with ultrasonic mixing to better disperse the thermally conductive particles 76 in the adhesive.

[0056] Thus, the adhesive layer 74 contains thermally conductive particles 76, which are randomly distributed throughout the adhesive layer 74.

[0057] Figure 15 shows more details of the graphite laminate layer. The adhesive layer 74 has been printed onto the upper surface of the graphite layer 70. Microbumps 78 are present on the adhesive layer 74 to enhance adhesion. The microbumps 78 can be adhesive dots or bumps, printed onto the upper surface of the adhesive layer 74 by stencil, special printing, or 3D printing. The microbumps 78 can be printed onto the adhesive layer 74 using an additional nozzle matrix.

[0058] Figures 16A-16BS show the case of attaching a single graphite laminate to the four outer sides of an inductor. In Figure 16A, a single large graphite sheet coated with adhesive is folded along the dashed lines. Therefore, folding is performed between portions A, B, C, and D, which correspond to graphite sheets 24, 26, 22, and 28, respectively.

[0059] Cutting is performed along the solid lines. Therefore, cutting is performed between portions A2, B2, X2, and D2 of the rear graphite sheet 54. Cutting is also performed between portions A1, B1, C1, and D1 of the front graphite sheet 52.

[0060] In FIG16B, after cutting a single large graphite sheet, the graphite sheet is applied to the outer surface of the upper magnetic core 32 and the lower magnetic core 34. Portion A forms the left graphite sheet 24, portion B forms the upper graphite sheet 26, portion C forms the right graphite sheet 22, and portion D forms the lower graphite sheet 28 (not shown).

[0061] Once part A is applied to the left side support of the upper magnetic core 32 and the lower magnetic core 34, part A1 can be folded onto the left front edge of the upper magnetic core 32 and the lower magnetic core 34 and pressed onto the front surface of the upper magnetic core 32 and the lower magnetic core 34 to form a part of the front graphite sheet 52. Part C1 can be folded onto the right front edge of the upper magnetic core 32 and the lower magnetic core 34 to form the right part of the front graphite sheet 52.

[0062] Then, portion B1 can be folded onto the top front edge of the upper magnetic core 32 and pressed onto the top front surface of the upper magnetic core 32 to form a portion of the front graphite sheet 52. Portion D1 can be folded onto the bottom front edge of the lower magnetic core 34 to form the bottom portion of the front graphite sheet 52.

[0063] Portions A2 and C2 can also be folded onto the back surfaces of the upper magnetic core 32 and the lower magnetic core 34, then portion B2 can be folded onto the back surface of the upper magnetic core 32, and then portion D2 can be folded onto the back surface of the lower magnetic core 34. Thus, individual graphite sheets can be folded, cut, and applied to these outer surfaces of the upper magnetic core 32 and the lower magnetic core 34, thereby forming graphite sheets 22, 24, 26, 28, 52, and 54 from individual graphite sheets.

[0064] Figure 17 highlights the application of a single large graphite sheet to the upper core 32 and the lower core 34. First, portion B is pressed onto the top surface of the upper core 32, for example, using a pressure roller or scraper. The applied pressure helps to press the adhesive into the surface of the upper core 32, flatten the graphite sheet, and remove air bubbles. Then, after forming the top graphite sheet 26 using portion B, the large graphite sheet is folded onto the left side surface of the upper core 32 and the lower core 34, and this portion of the graphite sheet is then pressed onto the left side surface of the upper core 32 and the lower core 34 using a pressure roller or scraper to form the left graphite sheet 24.

[0065] Continuing to use a pressure roller or scraper forms the right graphite sheet 22 and the bottom graphite sheet 28. Then, portions A1, B1, C1, and D1 are folded onto the front edges of the upper core 32 and the lower core 34 to form the front graphite sheet 52. Finally, portions A2, B2, C2, and D2 are folded onto the rear edges of the upper magnetic core 32 and the lower magnetic core 34 to form the rear graphite sheet 54.

[0066] Figure 18 shows three inductor cores laminated together with laminated graphite sheets. The inductor 30 can be formed by pressing graphite adhesive sheets onto the outer surfaces of the upper magnetic core 32 and the lower magnetic core 34 to form a right graphite sheet 22, a left graphite sheet 24, an upper graphite sheet 26, a lower graphite sheet 28, a front graphite sheet 52, and a rear graphite sheet 54. Larger graphite sheets (as shown in Figures 16A-16B) can be used to wrap the inductor 30. All graphite sheets 22, 24, 26, 28, 52, and 54 have adhesive attached to the inner surfaces facing the magnetic cores 32 and 34, such as the front adhesive sheet 53 and the rear adhesive sheet 55.

[0067] Multiple components identical to inductor 30 can be constructed, on which graphite sheets 22, 24, 26, 28, 52, and 54 are attached. Similar to inductor 30, the outer surfaces of both the front inductor 600 and the rear inductor 602 are covered with graphite sheets.

[0068] Graphite sheets are attached to the right, left, top, and bottom of the front inductor 600. The front inductor 600 also has a front graphite sheet 652 connected via a front adhesive ring 653 and a rear graphite sheet 654 connected via a rear adhesive ring 655.

[0069] The rear inductor 602 is provided with right, left, top, and bottom graphite sheets. The rear inductor 602 also has a front graphite sheet 752 connected by a front adhesive ring 753 and a rear graphite sheet 754 connected by a rear adhesive ring 755.

[0070] Lamination rings 690 and 790 are adhesive rings that laminate the core assemblies together. Lamination ring 690 has an adhesive that bonds the front inductor 600 to the front of the inductor 30, while lamination ring 790 bonds the rear inductor 602 to the rear of the inductor 30. More specifically, lamination ring 690 is sandwiched between the rear graphite sheet 654 and the front graphite sheet 52. Similarly, lamination ring 790 is sandwiched between the rear graphite sheet 54 and the front graphite sheet 752.

[0071] The front inductor 600 can be pressed onto the inductor 30, allowing the adhesive of the lamination ring 690 to be squeezed between the rear graphite sheet 654 and the front graphite sheet 52, forming a good bond with low contact resistance. The assembly of the front inductor 600 and the inductor 30 is then pressed onto the rear inductor 602, allowing the adhesive in the lamination ring 790 to be squeezed between the rear graphite sheet 52 and the front graphite sheet 752, forming a good bond with low contact resistance.

[0072] This pressing can be performed by loosely fitting the inductor 30, the front inductor 600, and the rear inductor 602 together with the lamination rings 690, 790, and then applying force to both ends of the entire sandwich and the inductor core.

[0073] The graphite ring 52 allows lateral heat conduction from the front end of the inductor 30. The graphite ring 654 allows lateral heat conduction from the front inductor 600.

[0074] Similarly, graphite ring 54 allows lateral heat conduction from the rear end of inductor 30. Graphite ring 752 allows lateral heat conduction from the rear inductor 602. 10 CN'120019454 A Specification 6 / 8 pages

[0075] Therefore, heat can be transferred laterally between the stacked inductor cores through the intermediate graphite rings 52, 654, 54, 752.

[0076] Figure 19 shows a stacked inductor with graphite rings between the inductor cores. The stacked inductor 90 has three inductor cores laminated together.

[0077] The outer surfaces of inductor 30, the front inductor 600, and the rear inductor 602 are all covered with graphite adhesive laminates, but not on the skeleton to which the wires 92 are wound. Each time the wires are wound, the wires 92 are wound on all three skeletons.

[0078] Figure 20 shows a stacked inductor connected to a heat sink. In the stacked inductor 90, a gap exists between the front inductor 600 and the inductor 30 to expose the wire 92 for inspection, but typically the front inductor 600 is pressed onto the inductor 30, with a graphite ring 52 and its adhesive layer sandwiched in between. The inductors 30, 600, and 602 are all connected to the heat sink 112. The heat generated by the inductor 30 can be propagated downwards through the right graphite sheet 22 and the left graphite sheet 24, passing through the upper magnetic core 32 and...The air gap between the lower magnetic cores 34. Then, this heat will be transferred to the bottom graphite sheet 28, and then to the heat sink 112, where it will dissipate through the air.

[0079] Similarly, the heat generated by the front inductor 600 and the rear inductor 602 can pass through the graphite sheets 622.722 through their air gap (FIG. 18) and then down into the heat sink 112.

[0080] The graphite rings 52, 54 (FIG. 18) not only allow heat to pass down through the air gap, but also allow heat to be transferred laterally from the inductor 30 to the front inductor 600 and the rear inductor 602.

[0081] The middle inductor 30 usually retains more heat because it cannot dissipate heat laterally and can only dissipate heat downwards to the heat sink. But the graphite ring 52 allows the heat on the front surface of the inductor 30 to be transferred laterally, through the front air gap, and then down into the heat sink 112 below the inductor 30. Similarly, the graphite ring 54 allows heat from the rear surface of the inductor 30 to be transferred laterally, through the rear air gap, and then downwards into the heat sink 112 below the inductor 30. Therefore, more heat can be effectively dissipated from the inductor 30.

[0082] Figures 21A-21B show different core types. Figure 21A shows a conventional E-type core with a rectangular frame formed by the middle legs of the upper core 32' and the lower core 34'. This rectangular frame or spool is undesirable because the wire is more difficult to wind around the square frame. Furthermore, the frame thickness being the same as the side legs causes the wire wound around the frame to extend beyond the side legs.

[0083] Many different E-type cores are available. Some E-type cores have a circular frame, which makes it easier to wind the wire. Additionally, if the frame is circular, the wire is less likely to break at the corners of the square frame. This improves reliability. The frame thickness can be reduced so that the side legs on both sides can extend beyond the wire wound around the frame.

[0084] Figure 21B shows a PQ core. A PQ core is a variant of the E-type core and can be considered a type of E core. In a PQ core, the shapes of the upper core 32” and the lower core 34” are modified. The center post or frame is circular to facilitate winding. The left and right legs are thicker than the frame. The shape of the PQ core can be optimized for switching power supplies (SMPS) or other AC applications.

[0085] When using a PQ core, the right graphite sheet 22 and the left graphite sheet 24 can be rectangular, but the top graphite sheet 26 and the bottom graphite sheet 28 may need to be cut to fit the top shape of the upper core 32” and the shape of the lower core 34”. Alternatively, the top graphite sheet 26 and the bottom graphite sheet 28 can be rectangular, and the graphite sheets can be larger or smaller than the top of the upper core 32". The front graphite sheet 52 and the rear graphite sheet 54 can be omitted or reduced in size, for example, only covering the left and right feet, without covering the top and bottom near the skeleton.

[0086] Figure 22 shows a stacked inductor with five magnetic cores. Although Figure 18 shows a transverse connection of two graphite rings.The three inductor cores are not present, but the stacked inductor 90' may include more cores. In this example, there are five cores with four graphite rings between them (CN 120019454 A specification, pages 7 / 8). The size of the heat sink 112 can be increased depending on the additional heat and size of the five-core stacked inductor 90'. [Alternative Embodiments]

[0087] The inventors have envisioned several other embodiments. For example, the upper and lower cores can have various combinations and variations. In some embodiments, some graphite adhesive laminates can be removed, or they can be cut into different shapes.

[0088] While E-type and PQ-type core variants have been described, the cores can also have various variations, such as pot-shaped cores with lateral extensions to more completely surround the frame 106, U-shaped cores lacking a second lateral foot, E1-type cores with an E-type upper core and a rectangular or I-shaped lower core, RM-type cores, RS-type cores, DS-type cores, etc. Various extensions and hybrid shapes and combinations of E-type magnetic cores are possible, such as EER type magnetic cores, ETD type magnetic cores, EP type magnetic cores, EC type magnetic cores, EFF type magnetic cores, E1 type magnetic cores, etc. Due to the high flexibility of graphite sheets, this invention can be applied to any magnetic core shape, size, and material.

[0089] Although it has been shown that a magnetic core has a skeleton, a left foot, and a right foot, a magnetic core may have only one foot and a skeleton. For a core rod, a graphite sheet is first attached to the core rod. Then, insulating tape is wrapped around the top of the graphite sheet. Finally, a coil is wound around the core rod. The feet may extend towards each other and merge at the back to form a semicircle. An air gap may exist in the skeleton and one foot, but not in the other foot. The air gap may be located near the bottom, rather than in the middle between the top and bottom. Other variations of the air gap are also possible. An inductor may have multiple air gaps or two or more core sections.

[0090] The magnetic core can be made of iron, iron oxide, ferrite, ferrite ceramics, silicon steel, amorphous steel, neodymium, iron powder, or other materials. Ceramic can also be used. Examples of ferromagnetic core materials include: silicon steel, powdered iron, nickel-iron alloys, amorphous metals, etc. Examples of non-ferromagnetic core materials include: manganese ferrite, non-magnetic ceramics, polymers. The magnetic core can be made of ferromagnetic or non-ferromagnetic materials. Ferrite is a general term referring to a mixture of iron oxide and other metal oxides. Other materials may include different mixtures, such as amorphous materials.

[0091] The air gap in the magnetic core can be provided with small shims at the corners to maintain the desired air gap thickness. These shims can be ceramic or other non-conductive materials. The air gap can be filled with dielectric materials or spacers that are non-electrical conductors and magnetic conductors, such as PET tape or FR4. However, the air gap is usually filled with air.

[0092] The air gap can be located in the middle of the inductor as shown, or it can be off-center, for example, near the bottom of the inductor.Instead of the top, the upper core can be larger than the lower core when the air gap moves downward. The air gap can be located at the bottom of the frame, and the lower core can be strip-shaped instead of E-shaped, such as an E1 core inductor.

[0093] Although it has been shown that graphite sheets are attached to all the outer surfaces of the E-core, the graphite sheet 26 attached to the top surface of the upper core and the graphite sheet 28 attached to the lower surface of the lower core can be removed because the graphite sheets 26, 28 do not span the air gap 10. Although it has been shown that the graphite sheets 22, 24 completely cover the outer surfaces of the left and right feet of the E-core, the size of the graphite sheets 22, 24 can be reduced so that they only partially cover the sides of the E-core. The size of the graphite sheets 22, 24 can be reduced to cover only the air gap 10 and parts of the sides of the upper and lower E-cores. Heat will still be transferred through the air gap 10, although not as efficiently as the larger graphite sheets 22, 24 (which have a larger surface area attached to the sides of the E-core). When there is good contact with the heat sink 112, for example through a connector, the bottom graphite sheet 28 can be removed.

[0094] The thermally conductive particles can be carbon nanotubes, ceramic powder, silicon carbide, alumina, boron oxide, magnesium oxide, or other thermally conductive materials. The adhesive can provide a lower contact resistance for the graphite sheet, allowing the graphite sheet to make better contact with the inductor core surface, thereby providing better thermal conductivity.

[0095] The outer edges of the upper core 32 and the lower core 34 can be rounded to allow the individual large graphite sheets to better fit the corners (Fig. 17). Sharp edges are more likely to cause the graphite laminate to crack or weaken. After the graphite sheet is attached, a coating can be applied to the inductor to protect the graphite laminate from scratches, abrasions, or damage. Microbumps (015) can be added to the adhesive to improve adhesion, or they can be removed to simplify the process. Many process methods and variations are possible.

[0096] Although Figure 18 shows two graphite rings 52.654 between the front inductor 602 and the inductor 30, it could also be a single graphite sheet with adhesive on both sides.

[0097] Although graphite sheets have been shown to be thermally conductive, other thermally conductive materials can be used instead of graphite. Thermally conductive sheets can be any thermally conductive film, such as copper, silicon, aluminum, etc., or a mixture of graphite and other materials. However, they may not be as effective as graphite sheets in improving thermal conductivity.

[0098] Terms such as up, down, above, below, horizontal, vertical, inside, outside, etc., are relative and depend on the viewing angle, and do not imply limitation of the invention to a specific viewing angle. Devices can be rotated such that vertical is horizontal and horizontal is vertical; therefore, these terms depend on the observer.

[0099] The background section of this invention may contain background information about the problem or environment of the invention, rather than describing the prior art of others. Therefore, the material included in the background section is not an admission of prior art by the applicant.

[0100] Any methods or processes described herein are machine-implemented or computer-implemented and are intended to be performed by machines, computers, or other devices, and are not intended to be performed solely by humans without machine assistance. Tangible results may include reports or other machine-generated displays on display devices such as computer monitors, projection devices, audio generation devices, and associated media devices, and may include hard-copy printouts that are also machine-generated. Computer control of other machines is another tangible result.

[0101] Any advantages and benefits described are not necessarily applicable to all embodiments of the invention. When the word “apparatus” appears in a claim element, the applicant intends that the claim element fall within the provisions of Section 112, paragraph 6 of 35 USC. Typically, one or more words precede the word “apparatus.” One or more words preceding the word “apparatus” are a label intended to facilitate reference to the claim element and not to express structural limitation. Such apparatus-plus-function claims are intended to cover not only the structures described herein for performing the function and their structural equivalents, but also equivalent structures. For example, although nails and screws have different constructions, they are equivalent structures because they both perform the fastening function. Claims that do not use the term "device" do not fall under the provisions of Section 112, paragraph 6 of 35 USC. Signals are typically electronic signals, but can also be optical signals, for example, transmitted via fiber optic lines. [0W2] The above description of embodiments of the invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, nor is it intended to limit the invention to the precise forms disclosed. Many modifications and variations are possible based on the above teaching. The purpose is that the scope of the invention is not limited by this detailed description, but rather by the appended claims. 13 CN 120019454 A Specification Drawings 1 / 11 Page 106 Figure 1 Prior Art 104 108 Figure 2 Prior Art 14 CN*120019454 A Specification Drawings Figure 3 Prior Art 104 ___ ___ 116 106 116 100 Figure 4 Prior Art 2 / 11 Page 15 CN 120019454 A Specification Drawings 3 / 11 Page 106 Figure 5 Prior Art 28 Figure 6 16 CN 120019454 A Specification Drawings 4 / 11 Page 28 Figure 7 Figure 8 17 CN 120019454 A Specification Drawings 5 / 11 Page Figure 9 tr32 22Xi Figure 10 18 CN*120019454 A Specification Drawings 6 / 11 Page 28 Figure 11 76 Figure 12 Figure 13 Prior Art 19 CN 120019454 A Instruction Manual Appendix 7 / 11 Page 70 Figure 14 Back A2 54 B2 54 54 C2D2 54 A 24 B 26 C 22 — D 28 Previous A1 52 B1 52 C1 52 D1 52 Figure 16A 20 CN*120019454 A Instruction Manual Appendix 8 / 11 Page Figure 16B 21 CN 120019454 A Instruction Manual Appendix 9 / H Page 754 600 Figure 18 Figure 19 22 CN*120019454 A Instruction Manual Appendix 10 / 11 Page Figure 20 Figure 21A 23 CN 120019454 A Instruction Manual Appendix li / ii Page 32H Figure 21B Figure 22 24

Claims

1. An inductor, comprising: an upper magnetic core of magnetic material having a top, an upper leg extending downward from the top, and an upper frame extending downward from the top; a lower magnetic core of magnetic material having a bottom, a lower leg extending upward from the bottom, and a lower frame extending upward from the bottom; a frame air gap between the upper frame and the lower frame; a leg air gap between the upper leg and the lower leg; a graphite sheet laminate having an adhesive attached to an inner surface of the graphite sheet, the graphite sheet laminate being attached to an outer surface of the upper leg by the adhesive and to an outer surface of the lower leg by the adhesive, the graphite sheet laminate spanning the leg air gap; as well as A conductive wire is wound around the upper frame multiple times and wound around the lower frame multiple times; The heat generated on the upper frame is transferred to the upper leg through the top, and then to the graphite sheet laminate, and then to the lower leg of the lower magnetic core through the leg air gap. The graphite sheet laminate thereby transfers heat from the upper magnetic core to the lower magnetic core across the leg air gap.

2. The inductor according to claim 1, wherein the outer surface of the upper leg is a surface facing away from the upper frame; wherein the outer surface of the lower support leg is a surface facing away from the lower frame; wherein the graphite sheet laminate is attached to the outer surface; wherein the graphite sheet laminate is not attached to the inner surface of the upper leg facing the upper frame; The graphite sheet laminate is not attached to the inner surface of the lower leg facing the lower frame.

3. The inductor of claim 2, wherein the upper magnetic core further comprises a second upper leg extending downward from the top portion, the second upper leg being located at a second end of the top portion, the second end of the top portion being opposite to a first end of the top portion, the first end having the upper leg extending downward; The lower magnetic core further includes a second lower leg extending upward from the bottom, the second lower leg is located at the second end of the bottom, the second end of the bottom is opposite to the first end of the bottom, and the first end of the bottom has the lower leg extending upward; wherein the upper frame is located between the upper support leg and the second upper support leg; The lower frame is located between the lower support leg and the second lower support leg.

4. The inductor according to claim 3, wherein the cross-section of the upper magnetic core is E-shaped; The cross section of the lower magnetic core is E-shaped; The inductor is an E-type magnetic core inductor.

5. The inductor according to claim 4, wherein the thickness of the upper skeleton is smaller than the thickness of the upper leg; The thickness of the lower frame is smaller than the thickness of the lower support leg. The inductor according to claim 5 , wherein the inductor is a PQ core inductor.

7. The inductor according to claim 4, further comprising: a heat sink attached to the lower magnetic core, the heat sink being used to forcibly dissipate heat into air surrounding the heat sink; wherein heat from the lower magnetic core is transferred to the heat sink; The heat from the upper magnetic core is transferred to the lower magnetic core through the graphite sheet laminate and then transferred to the heat sink.

8. The inductor according to claim 7, further comprising: A bottom graphite sheet laminate has an adhesive attached to an inner surface of the graphite sheet, the bottom graphite sheet laminate is attached to a bottom surface of the bottom of the lower magnetic core by the adhesive, and the bottom graphite sheet laminate is used to transfer heat from the lower magnetic core to the heat sink.

9. The inductor according to claim 8, further comprising: A top graphite sheet laminate having an adhesive attached to an inner surface of the graphite sheet, the top graphite sheet laminate being attached to a top surface of the top of the upper magnetic core by the adhesive.

10. The inductor according to claim 9, further comprising: a second leg air gap between the second upper leg and the second lower leg; a second graphite sheet laminate having an adhesive attached to an inner surface of the graphite sheet, the second graphite sheet laminate being attached to an outer surface of the second upper leg of the upper magnetic core by the adhesive, and the second graphite sheet laminate being also attached to an outer surface of the second lower leg of the lower magnetic core by the adhesive; wherein the second graphite sheet laminate spans the second leg air gap; The heat generated at the upper frame is transferred to the second upper leg through the top, and then to the second graphite sheet laminate, and then to the second lower leg of the lower magnetic core through the air gap of the second leg. Therefore, the second graphite sheet laminate also transfers heat from the upper magnetic core to the lower magnetic core through the second leg air gap.

11. The inductor according to claim 10, further comprising: a front graphite sheet laminate having an adhesive attached to the inner surface of the annular graphite sheet, the front graphite sheet laminate being attached to the front outer surfaces of the upper leg, the second upper leg, the top of the upper magnetic core, and the bottom of the lower magnetic core by the adhesive, the front graphite sheet laminate being not attached to the upper frame or the lower frame; A rear graphite sheet laminate having an adhesive attached to the inner surface of the annular graphite sheet, the rear graphite sheet laminate being attached to the rear outer surfaces of the upper leg, the second upper leg, the top of the upper magnetic core and the bottom of the lower magnetic core by the adhesive, the rear graphite sheet laminate being not attached to the upper frame or the lower frame.

12. The inductor of claim 11, wherein the binder is mixed with thermally conductive particles. The inductor of claim 12 , wherein the thermally conductive particles are carbon nanotubes.

14. The inductor according to claim 11, further comprising: The micro-bumps are formed on the adhesive, and are thicker areas of the adhesive, and are used to improve the adhesion between the graphite sheet and the surface of the upper magnetic core or the lower magnetic core.

15. The inductor of claim 11, wherein the graphite sheet laminate, the top graphite sheet laminate, the second graphite sheet laminate, the bottom graphite sheet laminate, the front graphite sheet laminate, and the back graphite sheet laminate are each part of a continuous graphite sheet laminate that is folded and cut to fit around the upper magnetic core and the lower magnetic core. 16 . The inductor of claim 15 , wherein the edge of the upper magnetic core and the edge of the lower magnetic core are rounded to prevent sharp edges from wearing the continuous graphite sheet laminate at the edge of the upper magnetic core and the edge of the lower magnetic core.

17. The inductor according to claim 11, wherein a second adhesive layer is further applied on the outer surface of the annular graphite sheet of the front graphite sheet laminate; Also includes: a front upper magnetic core having the same shape as the upper magnetic core, having a graphite sheet laminate attached to its outer surface, the front upper magnetic core being attached to the front graphite sheet laminate through the second adhesive layer; a front lower magnetic core having the same shape as the lower magnetic core, having a graphite sheet laminate attached to its outer surface, the front lower magnetic core being attached to the front graphite sheet laminate through the second adhesive layer; a front adhesive laminate ring applied between the front upper magnetic core and the upper magnetic core, the front adhesive laminate ring having a ring shape of the front graphite sheet laminate; a rear upper magnetic core having the same shape as the upper magnetic core and having a graphite sheet laminate attached to its outer surface, the rear upper magnetic core being attached to the rear graphite sheet laminate via a second rear adhesive layer; a rear lower magnetic core having the same shape as the lower magnetic core and having a graphite sheet laminate attached to its outer surface, the rear lower magnetic core being attached to the rear graphite sheet laminate through the second rear adhesive layer; and a rear adhesive laminate ring applied between the rear upper magnetic core and the upper magnetic core, the rear adhesive laminate ring having a ring shape of the rear graphite sheet laminate.

18. The inductor according to claim 17, wherein the conductive wire is wound on the upper skeletons of the front upper magnetic core, the upper magnetic core and the rear upper magnetic core for multiple times, wherein for each winding loop, the conductive wire is wound on the upper skeletons of the front upper magnetic core, the upper magnetic core and the rear upper magnetic core; The conductive wire is wound multiple times on the lower frames of the front lower magnetic core, the lower magnetic core and the rear lower magnetic core, wherein for each winding loop, the conductive wire is wound on the lower frames of the front lower magnetic core, the lower magnetic core and the rear lower magnetic core.

19. An inductor with improved thermal performance, comprising: An upper magnetic core made of ferrite or ferromagnetic material, comprising a top crossbar, an upper frame, a left upper leg and a right upper leg, wherein the upper crossbar is located in a top plane, the upper frame, the left upper leg and the right upper leg are located in a second plane perpendicular to the top plane, wherein the upper frame is located between the left upper leg and the right upper leg and is separated from the left upper leg and the right upper leg by an upper winding gap; A lower magnetic core made of ferrite or ferromagnetic material, comprising a bottom crossbar, a lower frame, a left lower leg and a right lower leg, wherein the bottom crossbar is located in a bottom plane parallel to the top plane, The lower frame, the left lower leg and the right lower leg are located in the second plane, wherein the lower frame is located between the left lower leg and the right lower leg and is separated from the left lower leg and the right lower leg by a lower winding gap; a left air gap located between a bottom of the upper left leg and a top of the lower left leg; a right air gap located between the bottom of the right upper leg and the top of the right lower leg; a frame air gap located between the bottom of the upper frame and the top of the lower frame; A wire, which is wound around the upper frame multiple times and around the lower frame multiple times, and the wire is wound in the upper winding gap and the lower winding gap; a left heat-conductive laminate applied to an outer surface of the left upper leg and to an outer surface of the left lower leg, the outer surface being a surface not facing the upper winding void or the lower winding void; wherein the left heat-conducting laminate plate spans the left air gap, and the left heat-conducting laminate plate is used to transfer heat from the upper magnetic core to the lower magnetic core through the left air gap; and a right heat-conductive laminate applied to an outer surface of the right upper leg and to an outer surface of the right lower leg, the outer surface being a surface not facing the upper winding void or the lower winding void; wherein the right heat-conducting laminate plate spans the right air gap, and the right heat-conducting laminate plate is used to transfer heat from the upper magnetic core to the lower magnetic core through the right air gap; wherein each heat-conducting laminate has an adhesive, the adhesive being applied on the surface of the heat-conducting layer facing the upper magnetic core or the lower magnetic core, the adhesive being used to reduce the contact resistance between the heat-conducting layer and the ferrite or ferromagnetic material of the upper magnetic core or the lower magnetic core; Thus, the left thermally conductive laminate increases heat transfer from the upper magnetic core to the lower magnetic core across the left air gap, and the right thermally conductive laminate increases heat transfer across the right air gap.

20. A laminated inductor with improved thermal performance, comprising a plurality of magnetic cores, each magnetic core comprising: An upper magnetic core made of ferrite or ferromagnetic material, comprising a top crossbar, an upper frame, a left upper leg and a right upper leg, wherein the top crossbar is located in a top plane, the upper frame, the left upper leg and the right upper leg are located in a second plane perpendicular to the top plane, wherein the upper frame is located between the left upper leg and the right upper leg and is separated from the left upper leg and the right upper leg by an upper winding gap; A lower magnetic core made of ferrite or ferromagnetic material, comprising a bottom crossbar, a lower frame, a left lower leg and a right lower leg, wherein the bottom crossbar is located in a bottom plane parallel to the top plane, the lower frame, the left lower leg and the right lower leg are located in the second plane, wherein the lower frame is located between the left lower leg and the right lower leg and is separated from the left lower leg and the right lower leg by a lower winding gap; a left air gap located between the bottom of the upper left leg and the top of the lower left leg; a right air gap located between the bottom of the right upper leg and the top of the right lower leg; A frame air gap, which is located between the bottom of the upper frame and the top of the lower frame; A wire, which is wound around the upper frame multiple times and around the lower frame multiple times, and the wire is wound in the upper winding gap and the lower winding gap; a left graphite laminate applied to an outer surface of the left upper leg and to an outer surface of the left lower leg, the outer surfaces being surfaces that do not face the upper winding void or the lower winding void; wherein the left graphite laminate spans the left air gap, and the left graphite laminate is used to transfer heat from the upper magnetic core to the lower magnetic core; and a right graphite laminate applied to an outer surface of the right upper leg and to an outer surface of the right lower leg, the outer surfaces being surfaces that do not face the upper winding void or the lower winding void; wherein the right graphite laminate plate spans the right air gap, and the right graphite laminate plate is used to transfer heat from the upper magnetic core to the lower magnetic core; wherein each graphite laminate has an adhesive, the adhesive being applied to the surface of the graphite layer facing the upper magnetic core or the lower magnetic core, the adhesive being used to reduce the contact resistance between the graphite layer and the ferrite or ferromagnetic material of the upper magnetic core or the lower magnetic core; Between a pair of adjacent magnetic cores among the plurality of magnetic cores, a front graphite laminate has adhesive on both surfaces of the graphite layer, the front graphite laminate being in a ring shape; wherein the front graphite laminate is attached to the front outer surfaces of the upper left leg, the upper right leg, the top crossbar of the upper magnetic core and the lower left leg, the lower right leg, the bottom crossbar of the lower magnetic core in the front magnetic core of the adjacent pair of magnetic cores by adhesive; wherein the front graphite laminate is attached to the rear outer surfaces of the upper left leg, the upper right leg, the top crossbar of the upper magnetic core and the lower left leg, the lower right leg, the bottom crossbar of the lower magnetic core in the back magnetic cores of the adjacent pair of magnetic cores by adhesive; Wherein, the front graphite laminate is not attached to the upper frame or the lower frame.

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