High-efficiency self-shielded inductor for high frequencies

Abstract

According to several embodiments, a high-frequency (HF) self-shielded inductor includes an outer shell having a dispersive or quasi-dispersive gap and two or more notches, an inner core disposed within the outer shell and having a dispersive or quasi-dispersive gap, coil windings disposed between the inner core and the outer shell, two end caps disposed at the opposing ends of the inner core and the outer shell, and a conductive shield disposed around the outer shell.

Description

[Technical Field]

[0001] Cross-references of related applications

[0001] This application claims the benefit under 35 U.S.SC Section 119 of U.S. Provisional Patent Application No. 63 / 496456, filed on 17 April 2023, which is incorporated herein by reference in its entirety.

[0002] Statement on federally funded research

[0002] N / A [Background technology]

[0003]

[0003] High-frequency (HF) power converters operating between 3 and 30 MHz offer several advantages, such as improved performance, reduced energy storage requirements, and miniaturization. In some applications, such as RF plasma generation and HF wireless power transmission, HF operation is naturally required. At lower frequencies, core magnetic components are used for miniaturization, high efficiency, and self-shielding. However, core materials conventionally used in power applications, such as MnZn ferrite, have high core losses and therefore perform poorly at frequencies above a few MHz. Furthermore, due to the skin effect and proximity effect, efforts are required to efficiently carry large currents at HF, and techniques such as Litz wire used to compensate for these losses become impractical at frequencies above a few MHz for manufacturing reasons. Therefore, designing core magnetic components requires effort in HF applications, as both copper losses and core losses increase significantly with frequency. As a result, air-core inductors are currently dominant in power applications in the HF (3-30 MHz) and VHF (30-300 MHz) ranges. [Overview of the Initiative]

[0004]

[0004] A weakness of air-core RF inductors, such as coreless solenoids, is that their magnetic fields are not shielded and can couple with other components of the system, resulting in large losses due to electromagnetic interference (EMI) and eddy currents. To maintain high efficiency, RF air-core inductors often require a large physical volume and are placed in a metal enclosure away from the control circuit to mitigate EMI. As a result, they often contribute significantly to the overall size and losses of the system and can be an obstacle to miniaturizing the system, such as in tunable matching networks.

[0005]

[0005] Advances have been made in the measurement and characterization of high-performance magnetic materials at HF ​​to achieve high efficiency and power density in RF applications. Low-permeability NiZn ferrite materials have been found to be suitable for the design of high-frequency AC inductors, and the proper design of cored inductors utilizing these materials can provide a better combination of size and efficiency than coreless inductors. However, achieving high-performance cored HF inductors requires design techniques to address skin loss and proximity loss. To minimize these losses, field balancing, single-layer winding, and quasi-distributed gaps can be used.

[0006]

[0006] Recent fabrications using these new design techniques and low-permeability RF magnetic materials have achieved an impressive combination of size and effect. However, many of these designs have resulted in a large magnetic field surrounding the inductor, raising concerns about EMI. For example, high-power core inductors achieve high Q, but like their air-core solenoid counterparts, they produce considerable external fringing flux. This unshielded external field from the inductor can couple with the surrounding components, resulting in EMI and losses. Therefore, there is a need for core HF inductors that can achieve high efficiency and also provide self-shielding to minimize losses and EMI occurring in the surrounding components.

[0007]

[0007] This disclosure presents a new design and model for an HF core-type self-shielded inductor. The improved design includes specific strategies to minimize losses resulting from 3D effects. Furthermore, the improved model takes these effects into account to allow for more accurate estimation of losses and enables the achievement of an optimal design. A thermal model is also presented to prevent the ferrite from overheating and potentially entering thermal runaway.

[0008]

[0008] According to one configuration of the present disclosure, a high-frequency (HF) self-shielded inductor includes an outer shell having a dispersive or quasi-dispersive gap and two or more notches, an inner core disposed within the outer shell and having a dispersive or quasi-dispersive gap, a coil winding disposed between the inner core and the outer shell, two end caps disposed at the opposing ends of the inner core and the outer shell, and a conductive shield disposed around the outer shell.

[0009]

[0009] In some embodiments, two or more notches in the outer shell have a total angular length sufficient to limit the flux density in the phi direction of the outer shell to less than 25% of the flux density in the z direction of the outer shell. In some embodiments, the magnetoresistance of the outer shell is less than the magnetoresistance of the inner core. In some embodiments, the magnetoresistance of the outer shell is between 20% and 80% of the magnetoresistance of the inner core. In some embodiments, the magnetoresistance of the outer shell is between 30% and 70% of the magnetoresistance of the inner core. In some embodiments, the magnetoresistance of the outer shell is between 40% and 60% of the magnetoresistance of the inner core. In some embodiments, the conductive shield includes a copper shield.

[0010]

[0010] In some embodiments, the coil winding is a single-layer helical winding. In some embodiments, the conductive winding is located within a window formed between the inner core and the outer shell, and the two leads of the single-layer helical winding are brought through the outer shell at a distance of 10% or less in the z direction from the total height of the window. In some embodiments, the coil winding includes two single-layer helical windings configured to carry current in opposing directions.

[0011]

[0011] In some embodiments, the coil winding includes a double-layer helical winding. In some embodiments, the internal core consists of alternating magnetic material disks and non-magnetic spacer material disks. In some embodiments, the outer shell consists of alternating pieces of magnetic and non-magnetic material, providing a return path for flux to flow. In some embodiments, the coil winding has evenly spaced windings wound around the internal core. In some embodiments, two or more notches have a total notch length sufficient to limit fringing at the notches causing proximity effect losses to an amount less than or equal to other proximity effect losses of the HF self-shielded inductor.

[0012]

[0012] In some embodiments, a conductive shield encloses the inner core, outer shell, two end caps, and coil windings to prevent flux leakage that would otherwise flow out of the HF self-shielded inductor. In some embodiments, the conductive shield is short-circuited. In some embodiments, the relative values ​​of the z-direction field in the inner core and outer shell are selected to minimize total losses. In some embodiments, both the outer shell and the inner core have a spiral core structure.

[0013] It should be understood that the individual elements of the various embodiments described herein can be combined to form other embodiments not specifically recited above. The various elements described in the context of one embodiment can also be provided separately or in any suitable sub-combination. It should also be understood that other embodiments not specifically described herein are also within the scope of the following claims.

[0014]

[0014] The manner in which the disclosed subject matter is made and used will be understood by reference to the detailed description in connection with the drawings, where like reference numerals refer to like elements.

Brief Description of the Drawings

[0015] [Figure 1A] FIG. 1A is a cross-sectional view of a self-shielded inductor taken along a polar axis. [Figure 1B] FIG. 1B is a three-dimensional (3D) cross-sectional view of the self-shielded inductor of FIG. 1A. [Figure 2] FIG. 2 is a schematic diagram showing a two-dimensional (2D) model of a self-shielded inductor. [Figure 3A] FIG. 3A is a perspective view of a coil winding that can be provided within a self-shielded inductor, illustrating a current in the z-direction. [Figure 3B] FIG. 3B is a top view of the self-shielded inductor, illustrating a field in the phi direction associated with a current in the z-direction. [Figure 4A] FIG. 4A is a top view of a self-shielded inductor having a notched outer core piece. [Figure 4B] FIG. 4B is a diagram showing a circuit for modeling the outer core piece of FIG. 4A. [Figure 5A] FIGS. 5A-D are perspective views of various types of coil windings that can be provided within a self-shielded inductor to reduce a current in the Z-direction, according to some embodiments. [Figure 5B]Figures 5A - D are perspective views of various types of coil windings that can be provided within a self - shielded inductor to reduce current in the Z - direction, according to some embodiments. [Figure 5C] Figures 5A - D are perspective views of various types of coil windings that can be provided within a self - shielded inductor to reduce current in the Z - direction, according to some embodiments. [Figure 5D] Figures 5A - D are perspective views of various types of coil windings that can be provided within a self - shielded inductor to reduce current in the Z - direction, according to some embodiments. [Figure 6A] Figures 6A and 6B are graphic diagrams illustrating the H - field in the YZ cross - section of a shielded inductor. [Figure 6B] Figures 6A and 6B are graphic diagrams illustrating the H - field in the YZ cross - section of a shielded inductor. [Figure 7A] Figures 7A - C are graphic diagrams illustrating the B - field in the YZ cross - section of a shielded inductor. [Figure 7B] Figures 7A - C are graphic diagrams illustrating the B - field in the YZ cross - section of a shielded inductor. [Figure 7C] Figures 7A - C are graphic diagrams illustrating the B - field in the YZ cross - section of a shielded inductor. [Figure 8] Figure 8 is a schematic diagram of a coil winding window, illustrating the derivation of window - gap magnetic resistance that models the flux jumping across the top and bottom of the winding window. [Figure 9] Figure 9 is a diagram showing a magnetic circuit for magnetic flux in the z - direction, according to some embodiments. [Figure 10A] Figures 10A - C are perspective views of a spiral - core structure that can be provided within a self - shielded inductor to reduce current crowding, according to some embodiments. [Figure 10B]Figures 10A-C are perspective views of spiral core structures that can be provided within a self-shielded inductor to reduce current congestion, according to several embodiments. [Figure 10C] Figures 10A-C are perspective views of spiral core structures that can be provided within a self-shielded inductor to reduce current congestion, according to several embodiments. [Figure 11A] Figures 11A and 11B are graphic diagrams showing the magnitude of the H field in the YZ cross-section for a spiral core structure. [Figure 11B] Figures 11A and 11B are graphic diagrams showing the magnitude of the H field in the YZ cross-section for a spiral core structure. [Figure 12] Figure 12 shows thermal resistance modules used to define a thermal resistance network according to several embodiments. [Figure 13] Figure 13 shows examples of how modular thermal modules can be connected to define a complete thermal resistance network according to several embodiments. [Modes for carrying out the invention]

[0016]

[0031] The drawings are not necessarily to scale and do not include all elements of the system; instead, the overall emphasis is on illustrating the concepts, structures, and technologies for which protection is sought.

[0017]

[0032] Figures 1A and 1B show a self-shielded inductor 100, such as that described in U.S. Patent Application Publication No. 2022 / 0262561, published on 18 August 2022, titled “Self-Shielded High Frequency Inductor”. The inductor 100 includes a “pot-core” structure 102 and a conductive outer shield 104 (e.g., copper foil) positioned around it. The core structure 102 is formed of an internal core 106 (sometimes referred to as the “internal post”), an outer shell 108 (sometimes referred to as the “outer core”), a coil winding window 110 (or “window”) formed between the internal core 106 and the outer shell 108, a first end cap 112, and a second end cap 114. The window 110 provides a distribution gap (or “void”) into which a coil winding 111 (e.g., a single-layer winding) can be positioned. The end caps 112 and 114, both of which may be cylindrical in shape, are positioned, as shown, to form the upper and lower walls of the window 110, respectively.

[0018]

[0033] As shown, the inner core 106, outer shell 108, and window 110 are at height h W This can be done. The core structure 102 has a radius R. For example, R may correspond to the radius of the end cap. The inner core 106 has a radius bR, where b is a number between 0 and 1. The outer shell 108 has an inner radius cR, where c is a number between 0 and 1. The relative effective permeability (RPM) of cores 106 and 108 is μ, respectively. γce and μ γse It has. Each of the end caps 112 and 114 has a relative permeability μ γ and height h e It has / 2 (shown in Figure 2).

[0019]

[0034] The outer shell 108 may have one or more notches, which are not visible in Figures 1A and 1B. For example, notches may be provided to remove the winding 111 from the window 110 and / or to help reduce the magnetic field component.

[0020]

[0035] The internal core 106 and / or outer shell 108 may have a quasi-dispersive gap structure. For example, as shown in Figure 1B, the internal core 106 and outer shell 108 may be formed of magnetic core pieces (e.g., ferrite disks) and non-magnetic spacers (e.g., disks of non-magnetic material) stacked alternately along the z-direction.

[0021]

[0036] The design methodology presented in U.S. Patent Application Publication No. 2022 / 0262561 and in "Design, implementation, and evaluation of high-efficiency high-power radio-frequency inductors" by RS Bayliss, RS Yang, AJ Hanson, CR Sullivan, and DJ Perreault on pages 881–888 of the 2021 IEEE Applied Power Electronics Conference and Exposition (APEC) uses a two-dimensional (2D) representation of the system to create shielded inductors. Based on this 2D analysis, a script was developed to determine the most efficient inductor configuration for a given volume.

[0022]

[0037] Figure 2 shows a 2D model of a self-shielded inductor, with the left side of the figure showing a front view of the inductor and the right side showing a top view of the inductor. The following dimensions may be used to design a self-shielded inductor. • Radius of the inner core bR • Inner radius of the outer shell cR • Distance S between the outer shield and the end capcsh ·Total radius of the inductor Rtot ·Radius R of the end cap ·Height h of the internal core piece ic ·Height of the gap of the internal core (e.g., height of the spacer) h ig ·Height h of the outer shell core piece oc ·Height of the gap of the outer shell (e.g., height of the spacer) h og ·Height h of the end cap e / 2 ·Height eh of the window ·Total height h of the inductor ·Height h of the winding winding ·Spacing s between turns of the winding tt ·Angular length α of the outer shell notch, with four notches each having an angular length α / 4 shown dispersed is shown.

[0023]

[0038] The self - shielded inductor described in U.S. Patent Application Publication No. 2022 / 0262561 can be simulated using a 3D simulator (e.g., ANSYS MAXWELL 3D), and the inductor loss can be compared with the loss predicted from the 2D model 200 in FIG. 2. In this model, a large difference in inductance can be seen as a result of the energy storage related to the unknown phi - direction field. The discrepancy between the loss predicted by the 2D model and the loss simulated by the 3D simulator indicates the need to consider additional effects that affect the loss.

[0024]

[0039] 2D analysis may not be suitable for designing inductors with a low number of turns (such as 2 or 3 turns) because the helical nature of low-turn windings negates 2D symmetry, resulting in designs that are unfeasible if 3D effects are not considered. Furthermore, since self-shielded inductors have a fairly small effective volume, thermal modeling is important. Therefore, determining an acceptable level of loss is essentially a matter of determining an acceptable level of heat.

[0025]

[0040] The following describes new designs and models for HF core-type self-shielded inductors. The improved designs include specific strategies to minimize losses resulting from 3D effects. Furthermore, the improved models take these effects into account, allowing for more accurate estimation of losses and enabling the achievement of an optimal design. A thermal model is also presented to prevent ferrite overheating and potential thermal runaway.

[0026]

[0041] A script (e.g., a MATLAB script) can be used to determine the minimum loss geometry for an improved design, and the geometry is parameterized, as shown in Figure 2. This script can be constructed using code developed in "Prospects for advances in power magnetics" by CR Sullivan on pages 1-9 of CIPS 2016; 9th International Conference on Integrated Power Electronics Systems, and in "Single-turn air-core coils for high-frequency inductive wireless power transfer" by G. Zulauf and JM Rivas-Davila on pages 2917-2932 of IEEE Transactions on Power Electronics, vol. 35, no. 3, 2020, but can be extended to include additional loss mechanisms, which will be described later.

[0027]

[0042] Table I shows the results of 3D simulations comparing the disclosed self-shielded inductor design with a conventional self-shielded inductor design, with respect to losses estimated from the model. As shown in the table, the disclosed design agrees well with the simulation, demonstrating the reliability of the modeling's effectiveness. The proposed model can achieve a more optimized design with a total loss reduction of more than 50%.

[0028] [Table 1]

[0029]

[0043] Moving on to Figures 3A and 3B, assuming a 2D model, the helical coil windings are represented as concentric circles parallel to each other. However, in real-world applications, these windings are interconnected, and as a result, the net current is directed towards the z-axis. For example, as shown in Figure 3A, the current i flowing through the coil winding 300 with helical windings inevitably produces the same net current in the z-direction. As shown in Figure 3B, this z-direction current is reflected in the phi-direction field B in the outer shell 322 of the self-shielded inductor 320. φ This creates these fields. In contrast, these fields are canceled out in the inner core 324. Note that Figure 3B shows a notch 326 in the outer shell 322, which acts as a manufacturing requirement to remove the winding from the window 328 and also helps to reduce the magnetic field component.

[0030]

[0044] The net z-direction current generates a magnetomotive force (MMF), which drives each piece and gap of the outer shell 322 in parallel. Furthermore, the outer shell always has at least one notch (e.g., notch 326) to allow the coil to exit the core window.

[0031]

[0045] Figure 4A shows the shell piece 400 having a notch 402. Figure 4B shows the circuit model 420 with respect to the shell core piece 400. Model 420 is related to the shell and R c,φ The first magnetic resistance 422a is, and R is in series with it and related to the notch. notch It includes a second magnetoresistance 422b and is driven by an associated MMF424 with a net z-direction current i (the same value as the drive current).

[0032]

[0046] The net current of the outer casing is as follows:

number

[0033]

[0047] The energy stored in the field also contributes to the inductance of the structure. Specifically, when the field is perpendicular to the "perpendicular" z-direction field, the inductance associated with the phi field is:

number

[0034]

[0048] When using this model, it can be understood here that the aforementioned choice of magnetoresistance modeling is insufficient to estimate core losses due to the phi-direction field, and thus underestimates this loss component. One reason for this is that the increase in the cross-sectional area of ​​the fringing path is not accounted for, so the notch magnetoresistance estimate is conservatively high. In designs where the shell gap height is high compared to the shell core thickness, the peak flux density was found to be considerably higher than predicted by the model.

[0035]

[0049] To explain the fringing field path, the model can be updated to use two parallel notch magnetoresistances, one related to the shell thickness and the other related to the thickness of the gap between shell pieces (e.g., spacers). This update allows for a better match of core losses, and further adjustments to the parallel magnetoresistance approximations may lead to an improved design.

number

[0036]

[0050] To mitigate the phi field, embodiments of the present disclosure may employ one or both of the following strategies: (1) increasing the magnetoresistance of the phi field path, and (2) using a winding structure that reduces or eliminates the net z-direction current flowing through the window, as illustrated in Figures 5A-D.

[0037]

[0051] Referring again to Figure 2, one approach to reducing the phi field is to increase the length (e.g., angular length) of the notches, which can be distributed symmetrically around the shell to avoid the problems that arise when using a single large latch. For example, as shown in the figure, four notches can be formed, each having an angular length α / 4 (e.g., in radians). However, this reduces the cross-sectional area of ​​the field in the z-direction on the shell.

[0038]

[0052] Another strategy for mitigating phi-direction fields and associated core losses is to eliminate the z-direction currents that give rise to these fields. This approach focuses on modifying the configuration or structure of the inductor windings. Various winding configurations for reducing or ideally eliminating net z-direction currents are described below according to embodiments of this disclosure. The disclosed winding configurations can effectively eliminate phi-direction fields, for example, by limiting them to less than 5% of the total field.

[0039]

[0053] Figure 5A shows a segmented winding configuration 500, in which the coil is divided into multiple single-turn segments 502a, 502b, 502c, etc., which can be connected in parallel. This configuration 500 can reduce the net z-direction current flowing through the winding and the overall capacitance of the structure.

[0040]

[0054] Figure 5B shows another winding structure 520, which provides a return path 522 for the winding inside the shell, eliminating or minimizing the net z-direction current and associated phi-direction field and core losses. This allows both winding leads 524, 526 to pass through the shell with a z-direction spacing 527 that is close enough to effectively eliminate the phi-direction field. For example, the z-direction spacing 527 of the leads may be less than or equal to 10% of the total height of the window. By incorporating a dedicated path 522 for the return current into the shell, the overall magnetic flux distribution is balanced, resulting in zero z-direction current. The space of the shell notch can be used to accommodate this return path.

[0041]

[0055] Figure 5C shows another winding structure 540, where, for example, the coil is divided into two mirror-image halves, namely an upper portion 542 with leads 544, 546 and a lower portion 548 with leads 550, 552, and the two coil portions 542, 548 are connected in parallel. As indicated by the arrows on the leads in the figure, the upper portion 542 can be connected to carry a net positive z-direction current, and the lower portion 548 can be connected to carry a net negative z-direction current. This configuration maintains the excitation of the z-direction field while halving the phi-direction field with respect to the same core geometry. Thus, core losses associated with the phi-direction field are greatly reduced.

[0042]

[0056] Figure 5D shows another winding configuration 560, in which the helical wire is wound in two layers, the first layer 562 wound "upward" from the first lead 568 and the second layer 564 wound "downward" to the second lead 570, providing a connection 566 between the two layers 562, 654. This arrangement of two windings can eliminate the z-direction field.

[0043]

[0057] The choice of strategy for mitigating the phi direction can be selected based on the requirements of the specific application and design. In some embodiments, a combination of the disclosed strategies may also be used within a self-shielded inductor.

[0044]

[0058] The helical windings of a coil create an "asymmetry" between the arrangement of the circular core pieces (which remains unchanged in the z-direction) and how the helical windings unfold through the winding window. In 2D, individual windings can be identified and described, starting and ending without any change in their z-direction displacement, like the core structure. However, in 3D, the windings are displaced in the z-direction by their height and even the spacing between windings. This phenomenon is particularly important at the end of the windings, where the way the flux traverses the region and how it results in current congestion associated with the field jumping across the winding window is altered.

[0045]

[0059] To understand these effects, we can consider how the z-direction flux path is affected by the geometry at the termination of the inductor. For example, Figures 6A-B and 7A-C show the magnitudes of the H field and B field in the YZ cross-section of a shielded inductor, respectively.

[0046]

[0060] Figures 6A and 6B are graphic diagrams showing the H field in the YZ cross-section of a shielded inductor, illustrating the tendency for the field to jump over the winding gap near the edge of the window. Figure 6A shows the line of sight and an arrow pointing to the "lost gap," while Figure 6B shows the core shell position.

[0047]

[0061] Figures 7A-C are graphic diagrams showing the B field in the YZ cross-section of a shielded inductor, illustrating the tendency for the field to jump over the winding gap near the edge of the window. Figure 7A shows the core shell position, Figure 7B shows arrows pointing to the line of sight and the "lost gap," and Figure 7C shows the end cap position.

[0048]

[0062] In Figure 6A, we can observe that the H field in the gaps gradually weakens from the top left to the bottom, becoming almost zero for the three gaps at the bottom. We can see that the H field weakens similarly from the bottom right to the top, which indicates that the magnetic field jumps across the window near the end of the winding. A similar phenomenon is observed in the end cap region in Figures 7A-C, where the B field is preferentially on one side of the core, suggesting that the other part of the end cap carries the minimum flux (coinciding with the field jumping across the gaps).

[0049]

[0063] The effect of termination-winding effects on 2D design is as summarized. By bypassing several gaps, the net magnetoresistance of the core becomes lower than expected, and as a result, combined with the inductance associated with the phi field, a higher simulated inductance is obtained compared to the design inductance. The upper and lower edges of the helical wire experience current congestion, which leads to a significant increase in copper losses with respect to the helical winding.

[0050]

[0064] The limitations of 2D analysis caused by these effects make it difficult to accurately optimize loss-related designs using this method. As a solution, this disclosure provides a method for incorporating the effects of the lost gap into an equivalent magnetic circuit model, enabling accurate optimization of the loss-related design and achieving precise results. Furthermore, this disclosure provides strategies for mitigating current congestion effects at the ends.

[0051]

[0065] Figure 6A-B shows where the last three gaps appear unused when viewed in the YZ section. This may be a result of the field jumping across the window when the window is a lower magnetoresistance path than the alternative outer shell and inner gap paths. To model this phenomenon, we can identify possible paths for the magnetic field across the winding window. Assuming that the only viable path is through the nonconductive portion of the window (i.e., the windings reject flux attempting to pass through them), the model can be updated by including the magnetoresistance associated with the "γ direction" window path. The spacing between the gaps presents viable paths for the flux (e.g., demonstrated by the field hotspots between the windings in Figure 6A-B), but all of this window jumping can be estimated to occur near the end of the windings to derive a more manageable model.

[0052]

[0066] Moving on to Figure 8, the coil winding window 800 is bounded by the upper and lower end caps 802 and 804. As shown in Figure 8 (and by the arrows in Figure 6A-B), gaps can exist at the top and bottom of the window 800 due to the helical shape of the coil winding 806. The derivation of the window gap magnetoresistance is provided to model the flux jumping across the top and bottom of the winding window.

[0053]

[0067] In the previously described assumption, the height of the region over which the field can jump over the window changes (or "unfolds") with the position of the helix, as shown on the right side of Figure 8. The effective magnetoresistance associated with this window jump path is

number

number

[0054]

[0068] Therefore,

number

[0055]

[0069] This magnetoresistance can be estimated to be in parallel with the numerous shell core pieces and shell gaps contained within the height of a single winding. That is,

number

[0056]

[0070] For example, in Figure 6A-B, the number of lost gaps is 3.9. Therefore, instead of using the magnetoresistance of all outer shells and outer gaps, a magnetoresistance model like that shown in Figure 9 can be used.

[0057]

[0071] Figure 9 shows a magnetic circuit 900 with respect to the magnetic flux in the z direction. The illustrative circuit 900 includes an excitation current source 902 connected in series with magnetoresistors 904a-g. Another magnetoresistor 904h may be connected at one end between magnetoresistors 904a and 904b and at the other end between magnetoresistors 904d and 904e. Another magnetoresistor 904i may be connected at one end between the current source 902 and magnetoresistor 904g and at the other end between magnetoresistors 904e and 904f. The magnetoresistors can be defined with respect to various elements shown in Figure 9, which are described in Table II.

[0058] [Table 2]

[0059]

[0072] Moving on to Figures 10A-C, as described above, there are challenges to several self-shielded inductor designs in which the core remains static while the helical winding unfolds in the z direction. Because these designs use a small number of windings, 2D symmetry is broken, resulting in large current congestion phenomena. To address this effect, embodiments of the present disclosure use a helically unfolding core structure while maintaining symmetry. This core structure ensures that each segment of the winding is placed in the ideal core and gap geometry, which creates a complete shroud on the winding. This shroud causes the z-direction flux to traverse through the end cap instead of jumping across the window.

[0060]

[0073] Figures 10A-C show examples of spiral core structures that can be provided within a self-shielded inductor according to several embodiments.

[0061]

[0074] Figure 10A shows a spiral core structure 1000, which includes a spiral-shaped inner core 1002 and a spiral-shaped outer shell 1004, neither of which has phi-direction notches.

[0062]

[0075] Figure 10B shows a spiral core structure 1020, which includes a spiral-shaped inner core 1022 having multiple phi-direction notches (e.g., notch 1026) and a spiral-shaped outer shell 1024 similarly having multiple phi-direction notches (e.g., notch 1028). In the example shown, both cores 1022 and 1024 have eight phi-notches, but it is also possible to select other numbers of phi-notches (e.g., based on application requirements and the modeling techniques described herein). In other embodiments, only the outer shell 1024 may have phi-notches.

[0063]

[0076] Figure 10C illustrates how spiral end caps 1042 and 1044 can be attached to a spiral core structure. For cores with phi notches, end caps 1042 and 1044 may also have notches in the phi direction (as shown in the figure). For cores without phi notches, the end caps can be designed without phi notches.

[0064]

[0077] Figures 11A and 11B illustrate the resulting H-field distribution in the YZ cross-section of the spiral core with and without a spiral end cap (Figure 11A) and with a spiral end cap (Figure 11B). Without the end cap, the winding losses are similar to those of a self-shielded inductor without a spiral core. With the spiral end cap, the current-concentration field no longer exists, and the simulated winding losses are equal to those that would be estimated without this current-concentration effect.

[0065]

[0078] These results confirm that significant reductions in winding losses (e.g., a 20% reduction) can be achieved by using core geometries that better mimic the 2D conditions used in the design. Specifically, configurations similar to those illustrated in Figures 10A-C can provide winding losses equivalent to those estimated from a simple 2D analysis.

[0066]

[0079] In practice, it may be necessary or desirable to formulate a thermal model for the design of self-shielded HF core inductors. Conductive outer shielding (e.g., copper shielding) significantly reduces the "effective" volume of the inductor, resulting in a considerably higher "effective" energy density. This increases the magnetic flux density within the ferrite, which can lead to thermal stress, thermal runaway, and potentially ferrite breakdown. Therefore, it may be important to develop a comprehensive thermal model to select the optimal cooling solution to ensure the success of the inductor.

[0067]

[0080] Here, a 2D (cylindrical) thermal model is presented, which is based on conductive and transmissive thermal resistance. This model may be useful for evaluating the relative effects of specific changing parameters, such as an increase in the number of gaps. The system can be dispersed into thermal modules as shown in Figure 12. As shown, module 1202 represents the internal core piece and winding mount, module 1204 represents the internal gap piece and winding mount, module 1206 represents the outer shell core piece and shield mount, module 1208 represents the outer gap piece and outer shell mount, module 1210 represents the winding, module 1212 represents the end cap, and module 1214 represents the outer shell. The definitions of each thermal resistance in Figure 12 are listed in Tables III and IV.

[0068]

[0081] The modules with respect to core pieces and gaps can be iterated to match the number of core pieces and gaps in the designed inductor. Figure 13 shows an example of how the modular thermal modules of Figure 12 can be connected to define the complete thermal resistance network 1300, with the same reference numbers in both figures representing the same elements. In this example, complete 2D symmetry is assumed, meaning that the phi direction is not included in this model. After comparing the results of the proposed thermal model with thermal simulations (e.g., simulations performed with ANSYS ICEPAK), a satisfactory level of agreement between the two could be observed.

[0069] [Table 3-1] [Table 3-2]

[0070] [Table 4-1] [Table 4-2]

[0071]

[0082] The scope of the claim and the term "including" used herein do not exclude other components or processes, and the indefinite articles "a" and "an" do not exclude plurals.

[0072]

[0083] Various embodiments of the conceptual system and method are described herein with reference to the relevant drawings. Alternative embodiments can also be conceived without deviating from the scope of the described concepts. Note that various connections and positional relationships (e.g., above, below, adjacent, etc.) are described between the components in the claims, detailed description, and drawings. These connections and / or positional relationships may be direct or indirect unless otherwise specified, and the claimed invention is not intended to be limited in this respect. Thus, the joining / connection of entities may refer to direct or indirect joining / connection, and the positional relationship between entities may refer to direct or indirect positional relationship. As an example of an indirect positional relationship, the discussion herein of an element or structure A joined / connected to an element or structure B includes a situation where one or more intermediate elements or structures (e.g., element C) are provided between elements A and B, regardless of whether the intermediate element(s) substantially alter the characteristics or functions of elements A and / or B.

[0073]

[0084] Furthermore, it should be understood that relative, directional, or reference terms (e.g., “up,” “down,” “left,” “right,” “top,” “bottom,” “vertical,” “horizontal,” “front,” “back,” “rear,” “forward,” etc.) and their derivatives are used simply to enhance the clarity of the diagram's description. These terms are not intended to be limiting, nor should they be considered limiting. They are merely used to facilitate the description of the drawing, and, in particular, to enhance the clarity of the description when dealing with relative relationships with respect to illustrative embodiments, where applicable. However, such terms are not intended to imply absolute relationships, positions, and / or directions. For example, with respect to an object or structure, the “up” or “top” surface can become the “down” or “bottom” surface simply by turning the object upside down. Yet, it is still the same surface, and the object is the same.

[0074]

[0085] The terms “placed on top,” “set on top,” “at the top,” “at the top,” or “located on top” mean that a first element, such as a first structure, is located on top of a second element, such as a second structure, and that intervening elements or structures (such as interface structures) may or may not be present between the first and second elements. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected in a manner that there are no intervening elements or structures between the interface of the two elements. The term “connection” can include indirect and direct connections.

[0075]

[0086] Order terms such as “first,” “second,” and “third” that modify the elements of a claim in the claims do not, by themselves, imply any priority, prerogative, or order of one element of a claim over another, nor any chronological order in which the actions of the method are performed, but are simply used as labels to distinguish one element of a claim with a particular name from another element with the same name (but using order terms).

[0076]

[0087] The terms “approximately” and “about” may be used to mean, in some embodiments, within ±20% of the target value, in some embodiments, within ±10% of the target value, in some embodiments, within ±5% of the target value, and in some embodiments, within ±2% of the target value. The terms “approximately” and “about” may include the target value. The term “substantially equal” may be used to mean, in some embodiments, values ​​that are within ±20% of each other, in some embodiments, values ​​that are within ±10% of each other, in some embodiments, values ​​that are within ±5% of each other, and in some embodiments, values ​​that are within ±20% of each other.

[0077]

[0088] The term “substantially” may be used in some embodiments to mean within ±20% of the comparative measurement, within ±10%, within ±50%, and even within ±2%. For example, a first direction that is “substantially” perpendicular to a second direction may, in some embodiments, be a first direction that forms an angle with the second direction within ±20% of 90 degrees, a first direction that forms an angle with the second direction within ±10% of 90 degrees, a first direction that forms an angle with the second direction within ±5% of 90 degrees, and even a first direction that forms an angle with the second direction within ±2% of 90 degrees.

[0078]

[0089] In the detailed description above, various features have been grouped together in one or more individual embodiments for the sake of efficiency in disclosure. This method of disclosure should not be interpreted as reflecting an intention that each claim requires more features than those explicitly stated herein. Rather, the configuration of the invention may be fewer than the total features of each disclosed embodiment.

[0079]

[0090] The terms “one embodiment,” “a certain embodiment,” “several embodiments,” or any derivatives thereof in the disclosure indicate that the described embodiments may include a particular configuration, structure, or feature, but all embodiments may include that particular configuration, structure, or feature. Furthermore, such terms do not necessarily refer to the same embodiments. Moreover, if a particular configuration, structure, or feature is described in relation to the knowledge of those skilled in the art, it will affect such configuration, structure, or feature in relation to other embodiments, whether explicitly described or not.

[0080]

[0091] The disclosed subject matter, in its applications, is not limited to the details of the configuration and arrangement of components described in the detailed description or shown in the figures. The disclosed subject matter can be used in other embodiments and can be implemented and carried out in various ways. Accordingly, those skilled in the art will understand that the concepts underlying this disclosure can be readily used as a basis when designing other structures, methods, and systems to accomplish some of the purposes of the disclosed subject matter. Accordingly, the claims should be considered to include such equivalent configurations, to the extent that they do not deviate from the spirit and scope of the subject matter of this disclosure.

[0081]

[0092] While the disclosed subject matter has been described and illustrated in the exemplary embodiments above, it should be understood that this disclosure is merely illustrative and that many changes may be made in the details of the implementation of the disclosed subject matter without deviating from the spirit and scope of the disclosed subject matter.

[0082]

[0093] A person skilled in the art can study the drawings, disclosures, and appended claims to understand and implement other variations of the disclosed embodiments when carrying out the claimed invention.

[0083]

[0094] The fact that specific means are described in separate, independent claims does not imply that a combination of those means cannot be used to obtain an advantage.

[0084]

[0095] None of the reference symbols in the claims should be considered to limit the scope.

[0085]

[0096] All publications and references cited herein are incorporated here in their entirety by reference.

Claims

1. A high-frequency (HF) self-shielded inductor, An outer shell having dispersed or semi-dispersive gaps and two or more notches, An internal core having a dispersed or semi-dispersive gap is disposed within the outer shell, A coil winding is disposed between the inner core and the outer shell, The inner core and the two end caps positioned at the opposing ends of the outer shell, A conductive shield arranged around the outer shell and HF self-shielded inductor including [specific feature].

2. An HF self-shielded inductor according to claim 1, wherein the two or more notches of the outer shell have a total angular length sufficient to limit the flux density in the phi direction of the outer shell to less than 25% of the flux density in the z direction of the outer shell.

3. An HF self-shielded inductor according to claim 1, wherein the magnetoresistance of the outer shell is smaller than the magnetoresistance of the inner core.

4. An HF self-shielded inductor according to claim 3, wherein the magnetoresistance of the outer shell is between 20% and 80% of the magnetoresistance of the inner core.

5. An HF self-shielded inductor according to claim 3, wherein the magnetoresistance of the outer shell is between 30% and 70% of the magnetoresistance of the inner core. HF self-shielded inductor.

6. An HF self-shielded inductor according to claim 3, wherein the magnetoresistance of the outer shell is between 40% and 60% of the magnetoresistance of the inner core. HF self-shielded inductor.

7. An HF self-shielded inductor according to claim 1, wherein the conductive shield includes a copper shield.

8. An HF self-shielded inductor according to claim 1, wherein the coil winding is a single-layer helical winding.

9. An HF self-shielded inductor according to claim 8, wherein the conductive winding is disposed within a window formed between the internal core and the outer shell, and two leads of a single-layer helical winding are brought through the outer shell at a z-direction spacing of 10% or less of the total height of the window.

10. An HF self-shielded inductor according to claim 1, wherein the coil winding includes two single-layer helical windings configured to carry current in opposing directions.

11. An HF self-shielded inductor according to claim 1, wherein the coil winding includes a double-layer helical winding.

12. An HF self-shielded inductor according to claim 1, wherein the internal core is composed of alternating magnetic material disks and non-magnetic spacer material disks.

13. An HF self-shielded inductor according to claim 1, wherein the outer shell is composed of alternating pieces of magnetic material and non-magnetic material, providing a return path for flux to flow.

14. An HF self-shielded inductor according to claim 1, wherein the coil winding has evenly spaced windings wound around the internal core.

15. An HF self-shielded inductor according to claim 1, wherein the two or more notches have a total notch length sufficient to limit the fringing at the notches causing proximity effect loss to an amount less than or equal to the other proximity effect loss of the HF self-shielded inductor.

16. An HF self-shielded inductor according to claim 1, wherein the conductive shield encloses the internal core, the outer shell, the two end caps, and the coil windings, thereby preventing flux from leaking out of the HF self-shielded inductor.

17. An HF self-shielded inductor according to claim 16, wherein the conductive shield is short-circuited.

18. An HF self-shielded inductor according to claim 1, wherein the relative values ​​of the z-direction fields in the internal core and the outer shell are selected to minimize total losses.

19. An HF self-shielded inductor according to claim 1, wherein both the outer shell and the inner core have a spiral core structure.

20. A high-frequency (HF) self-shielded inductor, Internal core and Outer shell and, Two end caps, A single-layer winding, wherein the two leads of the winding are brought through the outer shell at a narrow interval in the z direction in order to limit the core loss due to flux in the phi direction to a smaller value compared to the core loss due to core loss in the z direction, Copper shield and HF self-shielded inductor including [specific feature].

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