Permanent Magnet Hybrid Core Magnetic Device

Abstract

The disclosed embodiments may include systems and methods of a permanent magnet (PM) hybrid core inductor, and methods of fabricating them. The permanent magnet hybrid core may include a first set of members comprising a soft magnetic material, the first set of members forming a first gap between two end faces of the first set of members, and a second set of members comprising a permanent magnetic material and disposed adjacent to the first set of members, the second set of members providing a path at least partially parallel to the first set of members for the flow of magnetic flux lines. Some embodiments may include an inductor comprising a permanent magnet hybrid core, or a power conversion circuit having a switched capacitor circuit and a switching regulator, the switching regulator having an inductance, the inductance comprising a conductor wound around the permanent magnet hybrid core.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 366,620, filed on June 17, 2022, the entire content of which is incorporated herein by reference for all purposes.

[0002] The present disclosure generally relates to power electronics devices. More particularly, the present disclosure relates to voltage converter and / or regulator devices having large energy storage and low conduction losses.

Background Art

[0003] With the evolution of integrated circuit technology and computing power, the demand for power conversion, regulation, and its management has correspondingly increased. In power electronics devices such as converters or input filters operating in continuous conduction mode at high DC currents, the inductor's storage density can be increased by using core materials with high saturation flux density. However, at high - frequency operation in the range above MHz, conduction losses and core losses may also increase with the applied DC bias, thus limiting the performance of the inductor. Ferrite exhibits low core losses at high frequencies but has the problem of low saturation flux density. Therefore, it may be desirable to provide an inductor design that includes large energy storage, large saturation magnetic flux, low DC conduction losses, and / or low AC - related losses including low AC conduction losses.

Summary of the Invention

Means for Solving the Problems

[0004] Embodiments of the present disclosure provide a permanent magnet (PM) hybrid core inductor and a method of manufacturing the same. One aspect of the present disclosure is directed to a magnetic core. The magnetic core may include a first set of members comprising a soft magnetic material, the first set of members forming a first gap between two end faces of the first set of members, and a second set of members comprising a permanent magnetic material and disposed adjacent to the first set of members, wherein the second set of members provides a path at least partially parallel to the first set of members for the flow of magnetic flux lines.

[0005] Another aspect of the present disclosure is directed to a magnetic core. The magnetic core may include a permanent magnet having a curved surface and a soft magnetic member disposed adjacent to the curved surface of the permanent magnet. The soft magnetic member may form a first gap between two end faces of the soft magnetic member and may provide a hollow space for winding a conductor around the permanent magnet. The permanent magnet may provide a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines.

[0006] Yet another aspect of the present disclosure is directed to an inductor. The inductor may include a conductor wound around a magnetic core. The magnetic core may include a first set of members comprising a soft magnetic material, the first set of members forming a first gap between two end faces of the first set of members, and a second set of members comprising a permanent magnetic material and disposed in contact with the first set of members, wherein the second set of members provides a path at least partially parallel to the first set of members for the flow of magnetic flux lines.

[0007] Still another aspect of the present disclosure is directed to an inductor. The inductor may include a conductor wound around a magnetic core. The magnetic core may include a permanent magnet having a curved surface and a soft magnetic member disposed in contact with the curved surface of the permanent magnet. The soft magnetic member may form a first gap between two end faces of the soft magnetic member and may provide a hollow space for winding a conductor around the permanent magnet. The permanent magnet may provide a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines.

[0008] Yet another aspect of the present disclosure is directed to an apparatus. The apparatus includes a switching voltage regulator having an inductance. The inductance may include a conductor wound around a magnetic core. The magnetic core may include a first set of members comprising a soft magnetic material that forms a first gap between two end faces of the first set of members, and a second set of members comprising a permanent magnetic material and disposed adjacent to the first set of members, wherein the second set of members provides a path at least partially parallel to the first set of members for the flow of magnetic flux lines.

[0009] Yet another aspect of the present disclosure is directed to an apparatus. The apparatus includes a switching voltage regulator having an inductance. The inductance may include a conductor wound around a magnetic core. The magnetic core includes a permanent magnet having a curved surface and a soft magnetic member disposed adjacent to the curved surface of the permanent magnet. The soft magnetic member may form a first gap between two end faces of the soft magnetic member and may provide a hollow space for winding a conductor around the permanent magnet. The permanent magnet may provide a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines.

[0010] Yet another aspect of the present disclosure is directed to an apparatus. The apparatus includes a power conversion circuit having an inductance. The inductance may include a conductor wound around a magnetic core. The magnetic core may include a first set of members comprising a soft magnetic material that forms a first gap between two end faces of the first set of members, and a second set of members comprising a permanent magnetic material and disposed in contact with the first set of members, wherein the second set of members provides a path at least partially parallel to the first set of members for the flow of magnetic flux lines.

[0011] Yet another aspect of the present disclosure is directed to an apparatus. The apparatus includes a power conversion circuit having an inductance. The inductance may include a conductor wound around a magnetic core. The magnetic core includes a permanent magnet having a curved surface and a soft magnetic member disposed in contact with the curved surface of the permanent magnet. The soft magnetic member may form a first gap between two end faces of the soft magnetic member and may provide a hollow space for winding a conductor around the permanent magnet. The permanent magnet may provide a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines.

[0012] Yet another aspect of the present disclosure is directed to an apparatus. The apparatus may include a power conversion circuit having a switched capacitor circuit and a switching regulator, the switching regulator having an inductance, the inductance including a conductor wound around a magnetic core. The magnetic core may include a first set of members comprising a soft magnetic material, the first set of members forming a first gap between two end faces of the first set of members, and a second set of members comprising a permanent magnetic material and disposed adjacent to the first set of members, the second set of members providing a path at least partially parallel to the first set of members for the flow of magnetic flux lines.

[0013] Yet another aspect of the present disclosure is directed to an apparatus. The apparatus may include a power conversion circuit having a switched capacitor circuit and a switching regulator, the switching regulator having an inductance, the inductance including a conductor wound around a magnetic core. The magnetic core includes a permanent magnet having a curved surface and a soft magnetic member positioned adjacent to the curved surface of the permanent magnet. The soft magnetic member may form a first gap between two end faces of the soft magnetic member and may provide a hollow space for winding a conductor around the permanent magnet. The permanent magnet may provide a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines.

[0014] Additional features and advantages of the disclosed embodiments will be described in part in the following description, in part will become apparent from the description, or can be learned from the practice of the embodiments. The features and advantages of the disclosed embodiments can be realized and achieved by the elements and combinations described in the claims.

Brief Description of the Drawings

[0015] Embodiments and various aspects of the present disclosure are shown in the following forms for carrying out the invention and the accompanying drawings. It should be noted that various features are not drawn to scale according to the standard practice in this industry. In fact, for the sake of clarity of discussion, the dimensions of various features may be arbitrarily enlarged or reduced.

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DETAILED DESCRIPTION OF THE INVENTION

[0016] The following disclosure provides a number of different exemplary embodiments or examples for implementing different features of the provided subject matter. To explain the present disclosure, specific simplified examples of components and arrangements are described below. Of course, these are merely examples and are not intended to be limiting. Additionally, the present disclosure may repeat reference numerals and / or letters in various examples. This repetition is for the purpose of simplicity and clarity and does not itself determine the relationship between the various embodiments and / or configurations being discussed.

[0017] The terms used in this specification generally have their ordinary meanings in the art and in the specific context in which each term is used. The use of examples in this specification, including examples of any terms discussed herein, is for illustrative purposes only and in no way limits the scope or meaning of the present disclosure or any of the exemplified terms. Similarly, the present disclosure is not limited to the various embodiments given herein.

[0018] In this specification, terms such as "first", "second", etc. may be used to describe various elements, but these elements should not be limited by these terms. These terms are used to distinguish one element from another. For example, without departing from the scope of the embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] Furthermore, for the sake of simplicity in description, in this specification, spatial relationship terms such as "beneath", "below", "lower", "above", "upper", etc. may be used to describe the relationship of one element or feature shown in the figures to another element or feature. These spatial relationship terms are intended to encompass different orientations of the device in use or in operation in addition to the orientation shown in the figures. The device may be in a different orientation (rotated 90 degrees or otherwise), and the descriptive terms of the spatial relationships used herein may be interpreted similarly.

[0020] Some embodiments of the present invention may enable better passive component implementation in a power converter, which may alleviate the performance requirements for active components such as switching components.

[0021] Various non-limiting embodiments of the present disclosure are described in a particular context, namely, embodiments in high-density and high-efficiency voltage control devices. As used in the present disclosure, the term "voltage regulator" refers to a component of a power supply unit (PSU) configured to convert an input voltage into a stable output voltage. Most voltage regulators can be used for DC-DC power conversion, although some voltage regulators can also be used for AC-DC or AC-AC power conversion. A linear voltage regulator can be configured to output a lower, stable voltage signal from a higher voltage signal. In some cases, a linear voltage regulator can utilize input and output capacitors, or active pass devices such as bipolar junction transistors (BJTs) or metal-oxide-semiconductor field-effect transistors (MOSFETs) to control the voltage. However, a switching voltage regulator can be configured as a step-down converter (buck converter), a step-up converter (boost converter), or a buck-boost converter with the help of additional external components such as inductors, capacitors, FETs, or feedback resistors.

[0022] In some cases, a power converter can be used as a voltage regulator. The concepts of the present disclosure can apply to voltage regulators or power converters. A power converter that converts a higher input voltage power source to a lower output voltage level may be called a step-down or buck converter, because the converter "bucks" the input voltage. A power converter that converts a lower input voltage power source to a higher output voltage level may be called a step-up or boost converter, because the converter "boosts" the input voltage. Additionally, some power converters commonly known as "buck-boost converters" may be configured to convert an input voltage power source to a wide range of output voltages, where the output voltage can be either higher or lower than the input voltage. In various embodiments of the present disclosure, the power converter can be bidirectional and can be either a step-up converter or a step-down converter depending on how the power source is connected to the converter. In some embodiments, for example, an AC-DC power converter can be constructed from a DC-DC power converter by first rectifying the AC input voltage to a DC voltage and then applying the DC voltage to the DC-DC power converter. It should be understood that the permanent magnet hybrid core can also be used in other forms of AC-DC, DC-AC, and AC-AC power conversion.

[0023] The voltage regulator or power converter can be a switched capacitor power converter. FIG. 1 shows, for example, a hybrid switched capacitor power converter 100 that can be a multi-level buck power converter. The switched capacitor power converter 100 includes, for example, switches M1, M2, M3, M4, M5, and M6 arranged in series connection, flying capacitors C1 and C2, an inductor that can be a small low-profile chip inductor, an output capacitor C3, and a control / driver circuit (not shown) configured to control the switches (e.g., control to on or off, etc.). Specifically, each phase leg in the four-level converter includes three cells connected in series, and each cell includes a complementary switch pair (e.g., switches M1 and M6, switches M2 and M5, and switches M3 and M4) and a related flying capacitor (e.g., C1 or C2). During circuit operation, one switch is conducting in each cell at a given time. Thus, the multi-level power converter circuit 100 can operate in one of eight different states. Depending on the state, the voltage at the inductor node Lx can be at four different levels. To efficiently convert the voltage, the buck converter may rely on the inductor to store energy while converting from a higher voltage to a lower voltage.

[0024] As described above, voltage regulators such as switching voltage regulators may be partially dependent on capacitors and inductors to meet power conversion requirements. However, the inventors recognize that in power electronics devices involving large DC currents and high-frequency operation, inductors may have drawbacks related to size, conduction or core losses, or current-carrying capacity. The energy storage density of an inductor can be increased by using a core material with a high saturation magnetic flux density, but the associated core losses also increase, making the device inefficient. Core losses may become significant with increasing frequency (above MHz) and DC bias. Existing inductors may include ferrite cores with low core losses at high frequencies, but they also have a lower saturation magnetic flux density, limiting the DC performance of the inductor. Therefore, it may be desirable to provide an inductor with a higher relative permeability, a higher saturation magnetic flux density, and lower core losses to allow a higher current density to pass through the inductor at high frequencies.

[0025] The currently used ferrite has a low saturation magnetic flux density, but the inventors recognize that the available range of saturation magnetic flux density of the core material is not fully utilized in the design of inductors. Plot 210 in FIG. 2 shows the saturation behavior of a core material such as ferrite on the B-H curve or magnetization curve. It should be understood that the effect of hysteresis is omitted in the magnetization curve shown in FIG. 2 for the sake of convenience of explanation. In a DC-based application, the current, and thus the magnetic field (H), may be non-negative, which indicates that the core operates only on the positive side of the B-H curve and thus only uses half of the available saturation magnetic flux density. However, if the B-H curve can be offset as represented by plot 220 in FIG. 2 such that reverse saturation starts at a more positive magnetic field (H) or current, the core can utilize a wider range of saturation magnetic flux density in a DC-based application. Additionally, or alternatively, if reverse saturation can be set to start at H = 0 or zero current, the core can operate from -B sat to B satThe entire range of saturation magnetic flux density up to can be used. Some of the disclosed embodiments can address these and other issues.

[0026] In various embodiments of the present disclosure, an inductor design with a permanent magnet hybrid core can be disclosed. "Hybrid core" in the context of the present disclosure refers to the core of an inductor comprising a soft magnetic material and a permanent magnetic material. The soft magnetic material can include, but is not necessarily limited to, ferrite or powder core material. The permanent magnetic material can include, but is not necessarily limited to, neodymium iron boron (NdFeB). The disclosed inductor configuration can provide high peak energy storage, low DC conduction loss, low AC-related conduction loss, and core loss. The permanent magnet hybrid core inductor may be desirable in applications including, but not necessarily limited to, portable electronic devices such as tablets, mobile phones, or handheld computers, IoT (Internet of Things) devices, or applications involving large DC magnetic fluxes and high-frequency magnetic flux pulsations.

[0027] Some existing inductor designs include permanent magnets to improve the saturation performance of the inductor core. However, the permanent magnet is placed directly in the path of the winding magnetic flux, such as in the gap, for example, or directly in most of the path of the winding magnetic flux, such as adjacent to the gap. Placing a permanent magnet in the path of the winding magnetic flux can cause AC losses in the permanent magnet that increase with the operating frequency and may demagnetize the permanent magnet at high currents.

[0028] Reference is now made to FIG. 3, which is a schematic diagram of an exemplary permanent magnet hybrid core according to some embodiments of the present disclosure. FIG. 3 shows a perspective view of an exemplary magnetic core 300 that may include a soft magnetic material 310 and a permanent magnetic material 320, and a coil 330 continuously wound around the core. In some embodiments, the magnetic core 300 may include a first magnetic member comprising the soft magnetic material 310. The first magnetic member may form a first gap 312 between two end faces of the first magnetic member. The magnetic core may further include a second magnetic member comprising the permanent magnetic material 320. The second magnetic member may form a second gap 322 between two end faces of the second magnetic member. In some embodiments, the permanent magnetic material 320 may be disposed in contact with the soft magnetic material 310 so as to provide a path that is at least partially parallel or substantially parallel to the first magnetic member for the flow of magnetic flux lines. In such a configuration, the flow of magnetic flux lines in the permanent magnetic material 320 may oppose the flow of magnetic flux lines in the soft magnetic material 310 that is induced by a current flowing through the coil 330 wound around the soft magnetic material 310, the permanent magnetic material 320, or both. The magnetic flux lines in the permanent magnetic material 320 that oppose the magnetic flux lines in the soft magnetic material 310 may offset the B-H curve, increase the effective saturation magnetic flux, increase the peak energy storage, and decrease the conduction loss. In the context of the present disclosure, the “opposing flow” of magnetic flux lines is shown as the flow of magnetic flux lines in opposite directions between the two magnetic members. By way of example, if the magnetic flux lines flow in a clockwise direction in the soft magnetic material, the direction of the magnetic flux lines in the permanent magnetic material may be counterclockwise.

[0029] In some embodiments, the magnetic core 300 may comprise a first set of magnetic members, a second set of magnetic members, and a conductor (e.g., coil 330) wound around one or both of the magnetic members. As used herein, a "magnetic member" is shown as an integral or assembled structure of two or more components. By way of example, an assembled U-shaped magnetic member may include three rectangular pieces connected to form a substantially continuous shape that is small, even if there is a gap in the connection between the pieces. As used herein, a "set" of magnetic members is shown as a plurality of magnetic members such that a plurality of magnetic members arranged in parallel or in series form a single substantially continuous magnetic member.

[0030] In some embodiments, the first gap 312 may be filled with a material having a low conductivity. In some embodiments, the first gap 312 may be filled with a material having a low relative permeability. In the context of the present disclosure, "relative permeability" is shown as the ratio of the permeability of a particular medium to the permeability of free space or vacuum. In a preferred embodiment, the first gap 312 may be filled with a material having a permeability lower than that of the soft magnetic material 310. In some embodiments, the first gap 312 may be filled with a material including, but not necessarily limited to, a polymer, a ceramic, or any suitable material having a low conductivity and a low relative permeability. FIG. 3 shows an exemplary magnetic core design with two gaps, but it should be understood that there may be more gaps, for example, corresponding to the number of magnetic members.

[0031] In some embodiments, the second gap 322 may be similar to the first gap 312. The second gap 312 may be filled with a material having a low conductivity, a low relative permeability, or both. In some embodiments, the second gap 322 may be filled with a material including, but not necessarily limited to, a polymer, a ceramic, or any suitable material having a low conductivity and a low relative permeability. In some embodiments, as shown in FIG. 3, the second gap 322 may adjoin the first gap 312. However, in practice, as shown in the magnetic circuit diagram of FIG. 4 (described later), the two gaps 322 and 312 may function as a single gap because there is nothing to prevent the magnetic flux from either the soft magnetic material 310 or the permanent magnetic material 320 from passing through the gap 312 or 322.

[0032] In some embodiments, the coil 330 may include a helically wound coil made of a conductive material, such as copper, aluminum, silver, titanium, an alloy, or other suitable conductive material, but is not necessarily limited thereto. In a preferred embodiment, the coil 330 may be made of copper. In some embodiments, the coil 330 may be continuously wound around the soft magnetic material 310, or the permanent magnetic material 320, or both.

[0033] As shown in FIG. 3, the permanent magnetic material 320 may be disposed abutting parallel to the soft magnetic material 310. In some embodiments, the permanent magnetic material 320 may be arranged such that, in particular to maintain a low magnetic resistance, the upper surface of the permanent magnetic material 320 abuts the lower surface of the soft magnetic material 310 and physically contacts at least a portion of the lower surface of the soft magnetic material 310.

[0034] Reference is now made to FIG. 4, which shows an exemplary magnetic circuit model 400 of the magnetic core 300 according to some embodiments of the present disclosure. As shown, the reluctance R ferr of the ferrite and the reluctance R PM of the permanent magnet are in parallel with each other and are consistent with FIG. 3. The model 400 further includes a magnetomotive force (MMF) source Ni comprises. In the circuit model 400, the magnetic core 300 has a total core area A c and may have a proportion F of soft magnetic material (e.g., ferrite) of that area, and the permanent magnetic material may be (1 - F f ). FIG. 4 shows a Norton circuit model of a permanent magnet, but other suitable circuit models may also be used. When using the Norton model, the permanent magnet can be modeled using a reluctance having a permeability approximately equal to μ0, and a current source set by the residual magnetic flux density B f of the permanent magnet and the cross-sectional area A r . The maximum magnetic flux that can pass through the permanent magnet portion of the magnetic core 300 can be expressed as PM

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[0035] Referring to FIG. 4, the ferrite may be assumed to have a permeability much larger than that of the permanent magnet such that R ferr << R PM , and the gap characterizes the path of the winding reluctance such that R ferr << R gap . The winding flux from the MMF source Ni may mainly flow through the gap and the ferrite, and the permanent magnet flux may mainly flow in the opposite direction through the ferrite, so the total DC flux in the ferrite is offset (cancelled) while avoiding the winding flux. In an ideal situation, it can be assumed that substantially all of the permanent magnet flux can return through the ferrite. This is called the ideal model. However, in some embodiments, a portion of the permanent magnet flux may return through the ferrite (described later with reference to FIG. 5), which is called the modified model.

[0036] Based on the circuit model 400, a primary result regarding the maximum magnetic flux passing ability of the magnetic core 300 can be determined. For example, for a constant core area A in the magnetic core 300 c the maximum achievable magnetic flux can be adjusted based on the ferrite ratio F f used. Generally, as the ferrite ratio decreases, the permanent magnet ratio increases, and more permanent magnet flux can be made available to oppose the winding flux in the ferrite, so the magnetic flux passing ability of the magnetic core 300 increases. This can be

Equation

[0037] In some embodiments, to improve the saturation characteristics of the permanent magnet in the hybrid magnetic core (e.g., magnetic core 300), the residual magnetic flux density B of the permanent magnet r may be greater than the saturation magnetic flux density B of the ferrite max . This is because otherwise, it would involve replacing a part of the ferrite with a permanent magnet material with inferior magnetic flux ability characteristics, which would make the permanent magnet hybrid core inefficient in the hybrid design. Thus, based on Equation 3, for a large φ max,hybrid the ratio of the ferrite area may be small. However, Equation 3 only considers the saturation behavior of the permanent magnet hybrid core at large currents because the permanent magnet flux may saturate the ferrite in the reverse direction, and does not consider the saturation behavior of the permanent magnet hybrid core at small currents. In some applications, it may be desirable to prevent reverse saturation at zero current and above. In such cases, the permanent magnet flux is the maximum magnetic flux ability of the ferrite, or φ PM =B max A c F fmay not exceed. However, in order to maximize the magnetic flux passing ability of the permanent magnet hybrid core, it may be desirable to have the largest possible permanent magnet flux. By combining the reverse saturation constraint and the limit of Equation 3, the maximum magnetic flux of the permanent magnet hybrid core is

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[0038] The ratio F of the ferrite area that results in the optimal magnetic flux passing ability of the permanent magnet hybrid core f is determined based on Equation 1 and the reverse saturation constraint φ PM =2B max A c F f and can be determined. The optimal ratio of ferrite can be expressed as follows.

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[0039] Combining Equation 3 and Equation 5, the maximum magnetic flux passing ability and the effective saturation magnetic flux density of the permanent magnet hybrid core can be determined with respect to the material properties and geometric shape.

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[0040] The comparison of the maximum achievable magnetic flux density and the effective saturation magnetic flux density between the pure ferrite core and the hybrid magnetic core (e.g., magnetic core 300) based on Equation 6 and Equation 7 shows that the permanent magnet hybrid core

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[0041] Here, FIGS. 5A and 5B are referred to, which show the respectively simulated data plots of the optimal ferrite ratio and the maximum magnetic flux passing ability of the permanent magnet hybrid core using the modified model and the ideal model according to the embodiments of the present disclosure. In some embodiments, a certain proportion k PM of the permanent magnet flux may return through the ferrite. For example, if the core gap is relatively small, and as a result, the reluctance R ferr of the ferrite is not significantly smaller than the reluctance R gap of the gap, a part of the permanent magnet flux may instead cross the gap. From the perspective of the magnetic circuit model shown in FIG. 4, the permanent magnet flux may be divided in its return path, with some flux flowing through the ferrite and the rest flowing through the gap. In such a scenario, the maximum achievable magnetic flux of the permanent magnet hybrid core can be expressed as follows.

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[0042] To improve the saturation characteristics of the ferrite core by the permanent magnet, k PM ·B r >B maxso that the effective saturation magnetic flux density B of the permanent magnet r is greater than the effective saturation magnetic flux density B of the ferrite max . As k PM →1, it should be understood that the modified model approaches the ideal characteristics described previously. Since less permanent magnet flux offsets the flux in the ferrite, a higher percentage of permanent magnet may be desirable compared to the ideal characteristics. Additionally, since the percentage of the ferrite area may be lower, the permanent magnet hybrid core in the modified model may not be able to pass as much external flux as compared to the ideal characteristics, as shown by plot 500 in FIG. 5B.

[0043] In some embodiments, the modified model can be used to determine the lower limit of the percentage of ferrite for a set of material characteristics. In the permanent magnet hybrid core, for the permanent magnet to continue to operate usefully, the minimum k PM can be B max / B r . In the modified model, as k PM →B max / B r , the value of F f,opt →0.5. When F f <0.5, the ferrite portion can saturate in the reverse direction at zero current. Plot 500A in FIG. 5A shows the optimal ferrite percentage that does not saturate in the reverse direction at zero current. Plot 500A further shows that as the reluctance and gap increase, the modified model approaches the ideal characteristics. As expected, as the gap becomes smaller, the modified permanent magnet hybrid flux capability approaches the capability of a pure ferrite core, and the modified optimal ferrite percentage also approaches the lower limit of 0.5. It should be understood that the plot 500B showing the maximum flux passing capability of the permanent magnet hybrid core is normalized to the maximum flux passing capability of a pure ferrite core.

[0044] Permanent magnet hybrid cores, such as magnetic core 300, may have many advantages over existing designs of ferrite cores and can address one or more of the issues associated with existing ferrite-based cores in inductors used in power conversion applications. The permanent magnet hybrid core may have some or all of the advantages described herein. i. Larger saturation magnetic flux and effective saturation magnetic flux density Since the permanent magnet flux can oppose the total DC winding flux in the ferrite, the permanent magnet hybrid core has a higher magnetic flux passing ability, thereby offsetting the B-H curve for improved saturation performance while avoiding demagnetization by avoiding winding flux in the permanent magnet. High energy storage capacity and low conduction losses may be associated with higher saturation magnetic flux and effective saturation magnetic flux density. ii. Enhanced energy storage For a given DC resistance and inductance, the energy storage of an inductor may be determined by the saturation current, which depends on the maximum achievable magnetic flux. The permanent magnet hybrid core has

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[0045] In some embodiments, adding a permanent magnet to the ferrite can improve the saturation performance of the magnetic core, but at least the core loss can be higher due to a lower proportion of ferrite available for passing the alternating magnetic flux. However, since the permanent magnet hybrid core is targeted for DC center applications, the impact of the increase in core loss on the total loss may be negligible, if any.

[0046] Although the magnetic core 300 is described and shown as being used in an inductor having a single winding, it should be understood that it may also be used in a transformer having multiple windings or in connected inductors. Additionally, or alternatively, the magnetic core 300 may be designed to have multiple flux paths for direct current flux and / or alternating current flux. It should be understood that different core geometries and the positions of permanent magnets may be implemented as appropriate.

[0047] Reference is now made to FIG. 6A, which shows a schematic of an exemplary magnetic core 600 according to an embodiment of the present disclosure. The magnetic core 600 may include a dual U-core shape in which the core is divided into two symmetric U-shaped halves 602 and 604 along a symmetry axis 601. As shown, the magnetic core 600 may comprise a permanent magnet hybrid core including a soft magnetic material and a permanent magnetic material. In some embodiments, the U-shaped halves 602 and 604 may be oriented such that they are separated by two gaps along the symmetry axis 601. In some embodiments, one or both of the halves 602 and 604 may be made of a single piece or may be made of a plurality of pieces combined together to form a substantially continuous piece where the space between them is negligible. In some embodiments, the cross-section of the U-shaped halves 602 and 604 may be uniform, non-uniform, or may vary uniformly or non-uniformly along their length. For example, the end faces may have a larger cross-section and the central portion may have a smaller cross-section. Although not shown, it should be understood that other embodiments, cross-sections, geometries, or combinations thereof may be possible.

[0048] In some embodiments, the ratio of the minimum cross-sectional area of the first set of magnetic members to the sum of the minimum cross-sectional areas of the first and second sets of magnetic members is greater than 0.5, greater than 0.6, greater than 0.7, greater than 0.8, greater than 0.9, or greater than 0.95. The first set of magnetic members may include a soft magnetic material member, and the second set of magnetic members may include a permanent magnetic material member.

[0049] Figures 6B - 6J are schematic diagrams of exemplary embodiments of a permanent magnet hybrid core in a parallel configuration according to embodiments of the present disclosure. As used herein, "parallel embodiment" or "parallel configuration" refers to the position of the permanent magnet with respect to the position of the ferrite. In a parallel embodiment, the permanent magnetic material may be located adjacent to the inner surface, or the outer surface, or both, of the soft magnetic material. In some parallel embodiments, the permanent magnet may be surrounded or sandwiched by the soft magnetic material, or the soft magnetic material may be sandwiched or surrounded by the permanent magnetic material. In some embodiments, the permanent magnetic material may follow the soft magnetic material along a portion of its length.

[0050] Figure 6B shows a U - shaped half 600B of a magnetic core 600 comprising a permanent magnetic material adjacent and parallel to a soft magnetic material such that the permanent magnetic material is adjacent to the soft magnetic material. In such a configuration, the overall length of the soft magnetic material may be quite similar to or substantially the same as the overall length of the permanent magnetic material. The embodiment represented by 600B may be similar to the magnetic core 300 of FIG. 3. Figure 6C shows a U - shaped half 600C of a magnetic core 600 comprising a permanent magnetic material surrounding the soft magnetic material on the outer surface such that the overall length of the permanent magnetic material is longer than the overall length of the soft magnetic material. Figure 6D shows a U - shaped half 600D of a magnetic core 600 comprising a permanent magnetic material surrounded by the soft magnetic material such that the overall length of the soft magnetic material is longer than the overall length of the permanent magnetic material.

[0051] In some embodiments, the magnetic core 600 or half of the magnetic core 600 may include a third magnetic member comprising a soft magnetic material. The second magnetic member may be disposed between the first magnetic member and the third magnetic member. The second magnetic member may form a gap between two end faces of the second magnetic member, and the third magnetic member may form a third gap between two end faces of the third magnetic member. The second gap and the third gap may be adjacent to the first gap. FIGS. 6E and 6F respectively show the U-shaped halves 600E and 600F of the magnetic core 600 comprising a permanent magnetic material sandwiched between two members of a soft magnetic material. FIG. 6G shows the U-shaped half 600G of the magnetic core 600 comprising a permanent magnetic material member surrounded within a soft magnetic material such that all sides of the permanent magnetic material member are surrounded by the soft magnetic material.

[0052] In some embodiments, the ratio of the sum of the minimum cross-sectional areas of the first set of members and the minimum cross-sectional areas of the third set of members to the sum of the minimum cross-sectional areas of the first set of members, the minimum cross-sectional areas of the third set of members, and the minimum cross-sectional areas of the second set of members is greater than 0.5, greater than 0.6, greater than 0.7, greater than 0.8, greater than 0.9, or greater than 0.95. The first set and the third set of magnetic members may include soft magnetic material members, and the second set of magnetic members may include permanent magnetic material members.

[0053] In some embodiments, the magnetic core 600 or half of the magnetic core 600 may include a third magnetic member comprising a permanent magnetic material. The second magnetic member may be disposed between the first magnetic member and the third magnetic member. The second magnetic member may form a gap between two end faces of the second magnetic member, and the third magnetic member may form a third gap between two end faces of the third magnetic member. The second gap and the third gap may be adjacent to the first gap. FIGS. 6H and 6I respectively show the U-shaped halves 600H and 600I of the magnetic core 600 comprising a soft magnetic material member sandwiched between two members of a permanent magnetic material.

[0054] FIG. 6J shows a U-shaped half 600J of a magnetic core 600 that includes a soft magnetic material surrounded within a permanent magnetic material such that all sides of the soft magnetic material are surrounded by the permanent magnetic material. FIGS. 6B-6J show various parallel embodiments of a dual U-shaped core configuration, and it should be understood that other embodiments not shown may also be possible. It should be further understood that other geometric shapes, such as a pot core shape, may be used, without limitation.

[0055] Reference is now made to FIG. 7, which shows an exemplary non-parallel embodiment of half of a core 700 of a dual U-shaped inductor core, according to some embodiments of the present disclosure. The half core 700 may include a permanent magnet material member 720 positioned partially along an inner surface of a soft magnetic material member 710. In some embodiments, a permanent magnet hybrid core may include, as appropriate, a combination of parallel embodiments, partially parallel embodiments, or non-parallel embodiments. It should be understood that the position of the permanent magnetic material along the inner surface is merely exemplary and not limiting, and other embodiments may be possible. For example, in the embodiments shown in FIGS. 6B-6J, the permanent magnet may be disposed along only a portion of the length of the soft magnet.

[0056] Reference is now made to FIG. 8A, which shows a perspective view of an exemplary permanent magnet hybrid core inductor 800, according to some embodiments of the present disclosure. The inductor 800 may have a pot core shape. FIG. 8B is a schematic cross-sectional view of the inductor 800 along A-A', according to some embodiments of the present disclosure. The inductor 800 may include a soft magnet 810, a winding or coil 830 wound around the soft magnet, a permanent magnet 820 disposed at the center of the pot core, a magnetic flux guiding plate 840, and a shield 850.

[0057] The inductor 800 may include a permanent magnet hybrid core inductor. In some embodiments, the inductor 800 may include a permanent magnet 820 placed at the center of the pot core. The inductor 800 may further include a magnetic flux induction plate 840 on at least one end face such as the upper and lower faces of the inductor 800. In a preferred embodiment, as shown in FIG. 8B, the magnetic flux induction plates 840 may be disposed on the upper and lower faces of the inductor 800. The magnetic flux induction plate 840 may guide the magnetic flux radially outward from the permanent magnet 810. In some embodiments, the magnetic flux induction plate 840 may be made of a soft magnetic material with a high permeability and a high saturation magnetic flux density. In some embodiments, the magnetic flux induction plate 840 may be conductive. In a preferred embodiment, the magnetic flux induction plate 840 may be made of a material such as steel, but not limited thereto. A gap may be disposed in the outer shell to facilitate the magnetic flux returning from the magnetic flux induction plate 840 through the top and bottom of the soft magnet 810.

[0058] In some embodiments, the inductor 800 may further include a shield 850 made of a conductive material, including but not limited to copper, aluminum, and silver among conductive materials. The shield 850 may be disposed between the soft magnet 810 and the magnetic flux induction plate 840 to induce a DC magnetic flux path. In some embodiments, the magnetic flux induction plate 840 may incur large losses including hysteresis loss and eddy current loss when exposed to a high-frequency magnetic field. In some embodiments, the shield 850 may reduce the losses, for example, by blocking or reducing the AC winding magnetic flux entering the magnetic flux induction plate 840, while allowing the DC magnetic flux to flow between the magnetic flux induction plate 840 and the soft magnet 810. In some embodiments, the shield 850 may include an edge having a first thickness and a central portion having a second thickness different from the first thickness. However, in some embodiments, the edge of the shield 850 may be thinner than the rest of the shield 850. The thicker outer edge may reduce the eddy current loss of the shield 850. In some embodiments, the shield 850 may be made of a single continuous piece of conductive material or a plurality of pieces of conductive material.

[0059] Reference is now made to FIG. 9, which shows the winding flux path and the permanent magnet flux path in inductor 800 according to an embodiment of the present disclosure. Configuration 910 shows the permanent magnet flux path in an asymmetric cross-section of inductor 800. In configuration 910, the magnetic flux lines of the permanent magnet 820 can be guided radially outwards by the magnetic flux guiding plate 840 and back towards the soft magnet 810, so as to guide the magnetic flux lines through the upper plate of the pot core of inductor 800 and through its central post. Configuration 920 shows the DC winding flux flowing through the soft magnet 810 and across the outer gap between the two end faces of the soft magnet 810, without being affected by the PM (e.g., the PM is replaced by a non-magnetic material). Configuration 930 shows the combination of the permanent magnet flux lines and the DC winding flux lines in inductor 800.

[0060] Reference is now made to FIG. 10, which shows a comparison of simulated and experimental saturation behavior data between a permanent magnet hybrid core inductor and a pure ferrite core inductor according to some embodiments of the present disclosure. The simulations were performed using ANSYS Maxwell software with the 2D cylindrical finite element analysis (FEA) method. As shown in FIG. 10, for an acceptable 30% decrease in inductance, the prototype of the permanent magnet hybrid core inductor achieved a DC current of 11.1 A in simulation and 10.0 A in experiment. This difference can be explained by the physical embodiment of the commercially available permanent magnets, which includes stacks of permanent magnets each coated with a nickel coating. This coating may introduce a gap between the permanent magnet and the magnetic flux guiding plate 840 and may also introduce a magnetic short-circuit path for the permanent magnet flux, thus reducing the amount of permanent magnet flux opposing the DC winding flux in the soft magnet 810.

[0061] Based on simulation and experimental data, the permanent magnet hybrid core inductor outperforms the pure ferrite inductor. For example, for an acceptable 30% reduction in inductance, in the simulation, the permanent magnet hybrid core inductor achieved a 34% reduction in DC resistance at a maximum DC current 17% higher and an energy storage 37% higher.

[0062] Figure 11 shows a data plot of the frequency response of the inductance of a pure ferrite core inductor compared to a permanent magnet hybrid core inductor. As shown, the ferrite core inductor and the permanent magnet hybrid core inductor exhibit a fairly similar frequency response of inductance. As an example, at 1 MHz, the inductances of both the ferrite core inductor and the permanent magnet hybrid core inductor are 35.1 μH.

[0063] It is understood that, for clarity, some features of this specification described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of this specification described in the context of a single embodiment for brevity may also be provided separately, or in any suitable sub - combination, or as appropriate in any other described embodiment of this specification. Some features described in the context of various embodiments should not be considered essential features of those embodiments, except when the embodiments would not function without those elements.

[0064] Embodiments may further be described using the following clauses. 1. A first set of members comprising a soft magnetic material, the first set of members forming a first gap between two end faces of the first set of members, and A second set of members comprising a permanent magnetic material and positioned adjacent to the first set of members comprising A magnetic core in which the second set of members provides a path at least partially parallel to the first set of members for the flow of magnetic flux lines. 2. The magnetic core according to claim 1, wherein the first member set consists of one soft magnetic member. 3. The magnetic core according to claim 1, wherein the first member set consists of two soft magnetic members, each soft magnetic member having a U shape and providing one of the two end faces of the first member set. 4. The first member set and the second member set are configured such that the flow of magnetic flux lines in the second member set opposes the flow of magnetic flux lines in the first member set induced by a current flowing through a conductor wound around at least the first member set. The magnetic core according to claim 1. 5. The first member set and the second member set are configured such that the flow of magnetic flux lines in the second member set opposes the flow of magnetic flux lines in the first member set induced by a current flowing through a conductor wound around the first member set and the second member set. The magnetic core according to claim 4. 6. The first member set and the second member set are configured such that the flow of magnetic flux lines through the first member set induced by a current flowing through a conductor wound around at least the first member set, determined by finite element modeling, is at least 50 times the flow of magnetic flux lines through the second member set. The magnetic core according to claim 1. 7. The magnetic core according to claim 1, wherein the second member set provides a path at least partially parallel to the first member set for the flow of magnetic flux lines between the two end faces of the first member set. 8. The magnetic core according to claim 1, wherein the second member set provides a path substantially completely parallel to the first member set for the flow of magnetic flux lines. 9. The magnetic core according to claim 1, wherein the soft magnetic material is ferrite. 10. The magnetic core according to claim 1, wherein the soft magnetic material is a powder core material. 11. The magnetic core according to claim 1, wherein the first gap is filled with air. 12. The magnetic core according to claim 1, wherein the first air gap is filled with a material having a permeability lower than the permeability of the first set of members. 13. The magnetic core according to claim 1, wherein at least one member of the second member set is in contact with at least one member of the first member set. 14. The magnetic core according to claim 1, wherein the second member set forms a second gap between two end faces of the second member set, and the second gap is adjacent to the first gap. 15. The magnetic core according to claim 14, wherein the second member set consists of two permanent magnetic members, and each permanent magnetic member has a U shape and provides one of the two end faces of the second member set. 16. The magnetic core according to claim 1, wherein the overall length of the second member set is substantially the same as the overall length of the first member set. 17. The magnetic core according to claim 1, wherein the overall length of the second member set is shorter than the overall length of the first member set. 18. The magnetic core according to claim 1, wherein the overall length of the second member set is longer than the overall length of the first member set. 19. The magnetic core according to claim 1, wherein at least one member of the second member set is located adjacent to the outer surface of at least one member of the first member set. 20. The magnetic core according to claim 1, wherein at least one member of the second member set is located adjacent to the inner surface of at least one member of the first member set. 21. The magnetic core according to claim 1, wherein at least one member of the second member set is located in the hollow space provided by at least one member of the first member set. 22. The magnetic core according to claim 1, wherein at least one member of the first member set is located in the hollow space provided by at least one member of the second member set. 23. The magnetic core according to claim 1, wherein the ratio of the minimum cross-sectional area of the first member set to the sum of the minimum cross-sectional areas of the first member set and the second member set is greater than 0.5. 24. The magnetic core according to claim 23, wherein the ratio is greater than 0.6. 25. The magnetic core according to claim 24, wherein the ratio is greater than 0.7. 26. The magnetic core according to claim 25, wherein the ratio is greater than 0.8. 27. The magnetic core according to clause 26, wherein the ratio is greater than 0.9. 28. The magnetic core according to clause 27, wherein the ratio is greater than 0.95. 29. The magnetic core according to clause 1, further comprising a third member set including a soft magnetic material, wherein the second member set is positioned between the first member set and the third member set. 30. The magnetic core according to clause 29, wherein the second member set forms a second gap between two end faces of the second member set, the third member set forms a third gap between two end faces of the third member set, and both the second gap and the third gap are adjacent to the first gap. 31. The magnetic core according to clause 29, wherein the ratio of the sum of the minimum cross-sectional areas of the first member set and the third member set to the sum of the minimum cross-sectional areas of the first member set, the second member set, and the third member set is greater than 0.5. 32. The magnetic core according to clause 31, wherein the ratio is greater than 0.6. 33. The magnetic core according to clause 32, wherein the ratio is greater than 0.7. 34. The magnetic core according to clause 33, wherein the ratio is greater than 0.8. 35. The magnetic core according to clause 34, wherein the ratio is greater than 0.9. 36. The magnetic core according to clause 35, wherein the ratio is greater than 0.95. 37. The magnetic core according to clause 1, further comprising a third member set including a permanent magnetic material, wherein the first member set is arranged between the second member set and the third member set. 38. The magnetic core according to clause 37, wherein the second member set forms a second gap between two end faces of the second member set, the third member set forms a third gap between two end faces of the third member set, and both the second gap and the third gap are adjacent to the first gap. 39. The magnetic core according to clause 37, wherein the ratio of the sum of the minimum cross-sectional areas of the first member set to the sum of the minimum cross-sectional areas of the first member set, the second member set, and the third member set is greater than 0.5. 40. The magnetic core according to clause 39, where the ratio is greater than 0.6. 41. The magnetic core according to clause 40, where the ratio is greater than 0.7. 42. The magnetic core according to clause 41, where the ratio is greater than 0.8. 43. The magnetic core according to clause 42, where the ratio is greater than 0.9. 44. The magnetic core according to clause 43, where the ratio is greater than 0.95. 45. The magnetic core according to clause 1, where the first set of members comprises a plurality of soft magnetic materials. 46. The magnetic core according to clause 1, further comprising another soft magnetic member having a saturation magnetic flux density higher than that of the first set of members, and the other soft magnetic member is configured to induce magnetic flux flowing through at least one of the first set of members and the second set of members. 47. The magnetic core according to clause 46, further comprising a conductive shield, and the conductive shield is disposed adjacent to at least one member of another soft magnetic member and the first set of members. 48. The magnetic core according to clause 29, further comprising another soft magnetic member having a saturation magnetic flux density higher than that of the first set of members and the third set of members, and the other soft magnetic member is configured to induce magnetic flux flowing through at least one of the first set of members, the second set of members, and the third set of members. 49. The magnetic core according to clause 48, further comprising a conductive shield, and the conductive shield is disposed adjacent to at least one member of another soft magnetic member and at least one member of the first set of members or at least one member of the third set of members. 50. The magnetic core according to clause 37, further comprising another soft magnetic member having a saturation magnetic flux density higher than that of the first set of members, and the other soft magnetic member is configured to induce magnetic flux flowing through at least one of the first set of members, the second set of members, and the third set of members. 51. The magnetic core according to clause 50, further comprising a conductive shield, and the conductive shield is disposed adjacent to at least one member of another soft magnetic member and the first set of members. 52. The magnetic core according to clause 47, wherein the conductive shield comprises an edge portion having a first thickness and a central portion having a second thickness different from the first thickness. 53. The magnetic core according to clause 49, wherein the conductive shield comprises an edge portion having a first thickness and a central portion having a second thickness different from the first thickness. 54. The magnetic core according to clause 51, wherein the conductive shield comprises an edge portion having a first thickness and a central portion having a second thickness different from the first thickness. 55. A permanent magnet having a curved surface, A soft magnetic member positioned adjacent to the curved surface of the permanent magnet and the soft magnetic member forms a first gap between two end faces of the soft magnetic member, the soft magnetic member provides a hollow space for winding a conductor around the permanent magnet, the permanent magnet provides a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines, a magnetic core. 56. The magnetic core according to clause 55, wherein the flow of magnetic flux lines in the permanent magnet opposes the flow of magnetic flux lines in the soft magnetic member induced by the current flowing through the conductor. 57. The soft magnetic member and the permanent magnet are configured such that the flow of magnetic flux lines through the soft magnetic member induced by the current flowing through the conductor, determined by finite element modeling, is at least 50 times the flow of magnetic flux lines through the permanent magnet. The magnetic core according to clause 55. 58. The magnetic core according to clause 55, wherein the permanent magnet provides a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines between two end faces of the soft magnetic member. 59. The magnetic core according to clause 55, wherein the permanent magnet provides a path substantially completely parallel to the soft magnetic member for the flow of magnetic flux lines. 60. The magnetic core according to clause 55, wherein the soft magnetic material is ferrite. 61. The magnetic core according to clause 55, wherein the soft magnetic material is a powder core material. 62. The magnetic core according to clause 55, wherein the first gap is filled with air. 63. The magnetic core according to clause 55, wherein the first air gap is filled with a material having a magnetic permeability lower than that of the soft magnetic member. 64. The magnetic core according to clause 55, wherein at least a part of the soft magnetic member is in contact with at least a part of the permanent magnet. 65. The magnetic core according to clause 64, wherein the soft magnetic member is in contact with the curved surface of the permanent magnet. 66. The magnetic core according to clause 55, wherein the conductor is also wound around a part of the soft magnetic member, and the soft magnetic member is configured. 67. The magnetic core according to clause 55, further comprising a second soft magnetic member, wherein the second soft magnetic member is configured to induce magnetic flux from the permanent magnet to the soft magnetic member. 68. The magnetic core according to claim 67, further comprising a conductive shield, wherein the conductive shield is disposed adjacent to the second soft magnetic member and the soft magnetic member. 69. The magnetic core according to clause 68, wherein the conductive shield includes an edge having a first thickness and a central portion having a second thickness different from the first thickness. 70. An inductor comprising a conductor wound around the magnetic core according to any one of clauses 1 to 69. 71. An apparatus comprising a power conversion circuit having an inductance, wherein the inductance comprises a conductor wound around the magnetic core according to any one of clauses 1 to 69. 72. The apparatus according to clause 71, wherein the switching frequency of the switching voltage regulator is at least 1 MHz. 73. An apparatus comprising a power conversion circuit having an inductance, wherein the inductance comprises a conductor wound around the magnetic core according to any one of clauses 1 to 69. 74. An apparatus comprising a power conversion circuit having a switch capacitor circuit and a switching regulator, wherein the switching regulator has an inductance, and the inductor comprises a conductor wound around the magnetic core according to any one of clauses 1 to 69. 75. The apparatus according to clause 74, wherein the switching frequency of the switching regulator is at least 1 MHz.

[0065] The foregoing outlines the features of several embodiments so that those skilled in the art may better understand aspects of the present disclosure. Those skilled in the art should understand that they can readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and / or achieving the same advantages as the embodiments introduced herein. Those skilled in the art should also be aware that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure.

Claims

1. A first member set comprising a soft magnetic material, the first member set forming a first gap between two end faces of the first member set, and a second member set comprising a permanent magnetic material and arranged adjacent to the first member set comprising a magnetic core in which the second member set provides a path for magnetic flux lines that is at least partially parallel to the first member set.

2. The magnetic core according to claim 1, wherein the first member set consists of one soft magnetic member.

3. The magnetic core according to claim 1, wherein the first member set consists of two soft magnetic members, each soft magnetic member having a U shape and providing one of the two end faces of the first member set.

4. The first member set and the second member set are configured such that the flow of magnetic flux lines in the second member set opposes the flow of magnetic flux lines in the first member set induced by a current flowing through a conductor wound around at least the first member set.

5. The magnetic core according to claim 4, wherein the first member set and the second member set are configured such that the flow of magnetic flux lines in the second member set opposes the flow of magnetic flux lines in the first member set induced by a current flowing through a conductor wound around the first member set and the second member set.

6. The first member set and the second member set are configured such that the flow of magnetic flux lines through the first member set induced by a current flowing through a conductor wound around at least the first member set, determined by finite element modeling, is at least 50 times the flow of magnetic flux lines through the second member set.

7. The magnetic core according to claim 1, wherein the second member set provides a path for magnetic flux lines that is at least partially parallel to the first member set between the two end faces of the first member set.

8. The magnetic core according to claim 1, wherein the second member set provides a path for magnetic flux lines that is substantially completely parallel to the first member set.

9. The magnetic core according to any one of claims 1 to 8, wherein the soft magnetic material is ferrite.

10. The magnetic core according to any one of claims 1 to 8, wherein the soft magnetic material is a powder core material.

11. The magnetic core according to any one of claims 1 to 10, wherein the first gap is filled with air.

12. The magnetic core according to any one of claims 1 to 10, wherein the first air gap is filled with a material having a magnetic permeability lower than that of the first set of members.

13. The magnetic core according to any one of claims 1 to 12, wherein at least one member of the second set of members is in contact with at least one member of the first set of members.

14. The magnetic core according to any one of claims 1 to 13, wherein the second set of members forms a second gap between two end faces of the second set of members, and the second gap is adjacent to the first gap.

15. The magnetic core according to claim 14, wherein the second set of members consists of two permanent magnetic members, each permanent magnetic member having a U shape and providing one of the two end faces of the second set of members.

16. The magnetic core according to any one of claims 1 to 15, wherein the overall length of the second set of members is substantially the same as the overall length of the first set of members.

17. The magnetic core according to any one of claims 1 to 15, wherein the overall length of the second set of members is shorter than the overall length of the first set of members.

18. The magnetic core according to any one of claims 1 to 15, wherein the overall length of the second set of members is longer than the overall length of the first set of members.

19. The magnetic core according to any one of claims 1 to 18, wherein at least one member of the second set of members is located in contact with an outer surface of at least one member of the first set of members.

20. The magnetic core according to any one of claims 1 to 18, wherein at least one member of the second set of members is located in contact with an inner surface of at least one member of the first set of members.

21. The magnetic core according to any one of claims 1 to 18, wherein at least one member of the second set of members is located within a hollow space provided by at least one member of the first set of members.

22. The magnetic core according to any one of claims 1 to 18, wherein at least one member of the first set of members is located within a hollow space provided by at least one member of the second set of members.

23. The ratio of the minimum cross-sectional area of the first member set to the sum of the minimum cross-sectional area of the first member set and the minimum cross-sectional area of the second member set is greater than 0.5, the magnetic core according to any one of claims 1 to 22.

24. The ratio is greater than 0.6, the magnetic core according to claim 23.

25. The ratio is greater than 0.7, the magnetic core according to claim 24.

26. The ratio is greater than 0.8, the magnetic core according to claim 25.

27. The ratio is greater than 0.9, the magnetic core according to claim 26.

28. The ratio is greater than 0.95, the magnetic core according to claim 27.

29. Further comprising a third member set comprising a soft magnetic material, the second member set being disposed between the first member set and the third member set, the magnetic core according to any one of claims 1 to 28.

30. The second member set forms a second gap between two end faces of the second member set, the third member set forms a third gap between two end faces of the third member set of the members, and both the second gap and the third gap are adjacent to the first gap, the magnetic core according to claim 29.

31. The ratio of the sum of the minimum cross-sectional area of the first member set and the minimum cross-sectional area of the third member set to the sum of the minimum cross-sectional area of the first member set, the minimum cross-sectional area of the third member set, and the minimum cross-sectional area of the second member set is greater than 0.5, the magnetic core according to claim 29 or 30.

32. The ratio is greater than 0.6, the magnetic core according to claim 31.

33. The ratio is greater than 0.7, the magnetic core according to claim 32.

34. The ratio is greater than 0.8, the magnetic core according to claim 33.

35. The ratio is greater than 0.9, the magnetic core according to claim 34.

36. The ratio is greater than 0.95, the magnetic core according to claim 35.

37. Further comprising a third member set comprising a permanent magnetic material, the first member set being disposed between the second member set and the third member set, the magnetic core according to any one of claims 1 to 28.

38. The second member set forms a second gap between two end faces of the second member set, the third member set forms a third gap between two end faces of the third member set, and both the second gap and the third gap are adjacent to the first gap. The magnetic core according to claim 37.

39. The ratio of the total of the minimum cross-sectional areas of the first member set to the sum of the minimum cross-sectional areas of the first member set, the minimum cross-sectional area of the second member set, and the minimum cross-sectional area of the third member set is greater than 0.

5. The magnetic core according to claim 37 or 38.

40. The ratio is greater than 0.

6. The magnetic core according to claim 39.

41. The ratio is greater than 0.

7. The magnetic core according to claim 40.

42. The ratio is greater than 0.

8. The magnetic core according to claim 41.

43. The ratio is greater than 0.

9. The magnetic core according to claim 42.

44. The ratio is greater than 0.

95. The magnetic core according to claim 43.

45. The first member set includes a plurality of soft magnetic materials. The magnetic core according to any one of claims 1 and 3 to 44.

46. Further comprising another soft magnetic member having a saturation magnetic flux density higher than that of the first member set, the another soft magnetic member being configured to induce magnetic flux flowing through at least one of the first member set and the second member set. The magnetic core according to any one of claims 1 to 45.

47. Further comprising an electrically conductive shield, the electrically conductive shield being disposed adjacent to at least one member of the another soft magnetic member and the first member set. The magnetic core according to claim 46.

48. Further comprising another soft magnetic member having a saturation magnetic flux density higher than that of the first member set and the third member set, the another soft magnetic member being configured to induce magnetic flux flowing through at least one of the first member set, the second member set, and the third member set. The magnetic core according to any one of claims 29 to 36.

49. Further comprising an electrically conductive shield, the electrically conductive shield being disposed adjacent to at least one member of the another soft magnetic member and at least one member of the first member set or at least one member of the third member set. The magnetic core according to claim 48.

50. Further comprising another soft magnetic member having a saturation magnetic flux density higher than that of the first member set, wherein the another soft magnetic member is configured to induce magnetic flux flowing through at least one of the first member set, the second member set, and the third member set, the magnetic core according to any one of claims 37 to 44.

51. The magnetic core according to claim 50, further comprising a conductive shield, wherein the conductive shield is disposed adjacent to at least one member of the another soft magnetic member and the first member set.

52. The magnetic core according to any one of claims 47 or 49, wherein the conductive shield includes an edge portion having a first thickness and a central portion having a second thickness different from the first thickness.

53. The magnetic core according to claim 49, wherein the conductive shield includes an edge portion having a first thickness and a central portion having a second thickness different from the first thickness.

54. The magnetic core according to claim 51, wherein the conductive shield includes an edge portion having a first thickness and a central portion having a second thickness different from the first thickness.

55. A permanent magnet having a curved surface, A soft magnetic member positioned adjacent to the curved surface of the permanent magnet Comprising, The soft magnetic member forms a first gap between two end faces of the soft magnetic member, The soft magnetic member provides a hollow space for winding a conductor around the permanent magnet, The permanent magnet provides a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines, a magnetic core.

56. The magnetic core according to claim 55, wherein the flow of magnetic flux lines in the permanent magnet opposes the flow of magnetic flux lines in the soft magnetic member induced by the current flowing through the conductor.

57. The soft magnetic member and the permanent magnet are configured such that the flow of magnetic flux lines through the soft magnetic member induced by the current flowing through the conductor, determined by finite element modeling, is at least 50 times the flow of magnetic flux lines through the permanent magnet, the magnetic core according to claim 55.

58. The magnetic core according to claim 55, wherein the permanent magnet provides a path at least partially parallel to the soft magnetic member for the flow of magnetic flux lines between two end faces of the soft magnetic member.

59. The magnetic core according to claim 55, wherein the permanent magnet provides a path substantially completely parallel to the soft magnetic member for the flow of the magnetic flux lines.

60. The magnetic core according to any one of claims 55 to 59, wherein the soft magnetic material is ferrite.

61. The magnetic core according to any one of claims 55 to 59, wherein the soft magnetic material is a powder core material.

62. The magnetic core according to any one of claims 55 to 61, wherein the first gap is filled with air.

63. The magnetic core according to any one of claims 55 to 61, wherein the first air gap is filled with a material having a magnetic permeability lower than that of the soft magnetic member.

64. The magnetic core according to any one of claims 55 to 63, wherein at least a part of the soft magnetic member is in contact with at least a part of the permanent magnet.

65. The magnetic core according to claim 64, wherein the soft magnetic member is in contact with the curved surface of the permanent magnet.

66. The magnetic core according to any one of claims 55 to 65, wherein the conductor is also wound around a part of the soft magnetic member, and the soft magnetic member is configured.

67. The magnetic core according to any one of claims 55 to 66, further comprising a second soft magnetic member, wherein the second soft magnetic member is configured to induce magnetic flux from the permanent magnet to the soft magnetic member.

68. The magnetic core according to claim 67, further comprising a conductive shield, wherein the conductive shield is disposed adjacent to the second soft magnetic member and the soft magnetic member.

69. The magnetic core according to claim 68, wherein the conductive shield includes an edge having a first thickness and a central portion having a second thickness different from the first thickness.

70. An inductor comprising a conductor wound around the magnetic core according to any one of claims 1 to 69.

71. Comprising a switching voltage regulator having inductance, The device, wherein the inductor comprises a conductor wound around the magnetic core according to any one of claims 1 to 69.

72. The device according to claim 71, wherein the switching frequency of the switching voltage regulator is at least 1 MHz.

73. Comprising a power conversion circuit having inductance, The device, wherein the inductance comprises a conductor wound around the magnetic core according to any one of claims 1 to 69.

74. Comprising a power conversion circuit having a switch capacitor circuit and a switching regulator, The switching regulator has inductance, An apparatus, wherein the inductor comprises a conductor wound around the magnetic core according to any one of claims 1 to 69. **Claim 75** The apparatus according to claim 74, wherein the switching frequency of the switching regulator is at least 1 MHz.

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