Magnetic core considering size resonance and magnetic element, inductor and transformer comprising same

Abstract

The invention discloses a magnetic core considering size resonance and an inductor and a transformer comprising the same, a cavity is formed in the magnetic core, the cavity is defined by a peripheral wall with a preset wall thickness, and the peripheral wall is made of a magnetic material. By adopting the hollow structure, the high-frequency eddy current loss can be effectively inhibited, and the total loss and heating of the magnetic core under high frequency can be reduced, so that the magnetic element can be more stably and efficiently applied to modern high-frequency power electronic technology occasions.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, specifically relating to a magnetic core that takes into account size resonance and magnetic components, inductors, and transformers containing the same. Background Technology

[0002] In recent years, with the application of wide-bandgap semiconductor devices such as gallium nitride and silicon carbide, the operating frequency of modern power electronic converters is constantly developing towards megahertz (MHz) and higher frequencies. Under this trend of higher frequencies, the design of magnetic components faces severe challenges.

[0003] Toroidal cores are one of the most widely used core structures, but in high-frequency applications, especially those requiring larger dimensions to handle higher power, their performance is severely limited by size resonance. Size resonance refers to electromagnetic wave oscillations that occur when the physical dimensions of the core are close to the wavelength of the electromagnetic wave. Once electromagnetic wave oscillations occur, the effective permeability of the core drops sharply, while magnetic losses increase rapidly, leading to performance degradation or even failure of the component at high frequencies.

[0004] In existing technologies, the standing wave resonant frequency of traditional solid toroidal magnetic cores is strictly inversely proportional to their radial thickness. To increase the dimensional resonant frequency to accommodate higher operating frequencies, designers are forced to reduce the radial thickness of the core. However, for solid structures, this reduction in thickness is systemic, resulting in a linear and significant reduction in the effective magnetic cross-sectional area of ​​the core. Furthermore, reducing the thickness of solid cores cannot support the high power and heat dissipation challenges of practical applications.

[0005] In summary, the existing solid toroidal magnetic core structure, under the constraint of electromagnetic wave oscillation, creates an irreconcilable contradiction between high operating frequency and high power capacity, which has become a technical bottleneck restricting the development of MHz-level high-frequency, high-power magnetic components. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic core that takes into account size resonance, as well as magnetic components, inductors, and transformers containing the core. By employing a hollow structure, high-frequency eddy current losses can be effectively suppressed, and the total loss and heat generation of the magnetic core at high frequencies can be reduced.

[0007] To achieve the above objectives, the solution of the present invention is:

[0008] A magnetic core considering size resonance, wherein a cavity is formed inside the magnetic core and the cavity is surrounded by a peripheral wall having a predetermined wall thickness, the peripheral wall being a magnetic material.

[0009] The cross-section of the cavity can be rectangular, circular, or elliptical, or other shapes may be used.

[0010] The aforementioned magnetic core is a toroidal core. The toroidal body has an outer diameter, an inner diameter, and an axial height. The cavity is disposed along the circumferential path of the toroidal core, forming a closed annular channel inside the toroidal core. The annular cavity is continuously and closedly passed through the circumference of the toroidal body, and in any radial axial section of the toroidal body, the annular cavity presents a basically square or rectangular outline.

[0011] The aforementioned annular channel is filled with a cooling medium or an insulating and thermally conductive medium to reduce the operating temperature of the annular magnetic core.

[0012] The aforementioned annular channel is filled with a low-permeability non-magnetic material to support the upper wall, lower wall, inner sidewall, and outer sidewall, and to block internal magnetic leakage.

[0013] The aforementioned preset wall thickness is less than the critical size resonant thickness of the magnetic material at the operating frequency, in order to reduce eddy current losses.

[0014] The cross-sectional area of ​​the cavity and the total cross-sectional area of ​​the magnetic core have a preset area ratio; the preset area ratio is configured to minimize the high-loss region inside the magnetic core while maintaining the inductance coefficient of the magnetic core to meet the design requirements.

[0015] The magnetic core can be made of materials with size resonance effects, such as ferrite or magnetic powder core. The preferred materials are any one or a combination of at least two of manganese-zinc ferrite, nickel-zinc ferrite, and amorphous nanocrystalline magnetic materials.

[0016] The aforementioned magnetic core comprises several core units, each having a first end and a second end, and forming a hollow structure from the first end to the second end; the several core units are arranged end to end to form a closed magnetic core.

[0017] A magnetic element includes a magnetic core and at least one winding, the winding being wound around the magnetic core; the magnetic core is as described above.

[0018] A transformer includes the magnetic element as described above.

[0019] An inductor comprising the magnetic element as described above.

[0020] By adopting the above solution, the present invention has at least the following beneficial results:

[0021] (1) Significantly improves the frequency of delayed electromagnetic wave oscillation. This invention designs a hollow structure, physically decomposing the single, large radial thickness of the original solid magnetic core into thinner inner and outer sidewalls, thus shifting its resonant point backward. This weakens the standing wave effect inside the magnetic core and effectively improves the operating bandwidth of the magnetic element. Therefore, this invention significantly improves the effective operating frequency of the magnetic core while keeping the overall outer and inner diameters of the magnetic core essentially unchanged.

[0022] (2) Significantly reduce high-frequency losses and improve efficiency. The hollow rectangular cross-section design of the present invention reconstructs the magnetic core's magnetic cross-section from a physical perspective. This structure optimizes the high-frequency magnetic flux distribution and eddy current path inside the magnetic core, enabling the magnetic core to achieve a significant reduction in high-frequency losses and a substantial delay in the size resonance frequency while maintaining the same macroscopic outer dimensions. This allows the magnetic components to be applied more stably and efficiently in modern high-frequency power electronics applications.

[0023] (3) Improved heat dissipation performance. The introduction of the internal rectangular cavity makes the heat dissipation surface area of ​​the magnetic core larger than that of a solid magnetic core of the same shape, which is conducive to the heat being dissipated from the inside. In particular, when combined with a cooling medium, it can further improve the thermal stability and power density of the component.

[0024] This invention has the ability to optimize the inherent high-frequency characteristics based on passive physical structures, breaking through the physical performance limitations of traditional toroidal magnetic cores in high-frequency applications, and providing a brand-new technical path for improving the operating frequency, operating efficiency and power density of high-frequency magnetic components based on toroidal magnetic cores.

[0025] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the annular cavity ferrite structure provided in an embodiment of the present invention;

[0027] Figure 2 It is a simulation cloud map of the magnetic flux density distribution of a solid toroidal core under specific high-frequency conditions;

[0028] Figure 3 This is a simulation cloud diagram of the magnetic flux density distribution of the hollow toroidal magnetic core according to an embodiment of the present invention under the same conditions;

[0029] Figure 4 This is a comparison curve of the normalized relative permeability of the annular cavity ferrite structure of the present invention and the solid magnetic core of the prior art as a function of frequency.

[0030] Figure 5 This is a schematic diagram of a rectangular cavity ferrite structure provided in an embodiment of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1:

[0033] Please see Figure 1 This invention provides a magnetic core structure considering size resonance, comprising an annular body with a hollow rectangular cross-section, the hollow rectangular cross-section being continuous and closed along the circumference of the annular body. The hollow rectangular cross-section is formed by an upper wall, a lower wall, an inner side wall, and an outer side wall, creating an internal rectangular cavity. In this embodiment, the magnetic core is made of ferrite material. This annular cavity ferrite structure is used to physically optimize high-frequency magnetic flux and eddy current paths, physically removing the high magnetic density region under size resonance, thereby delaying the size resonance frequency and significantly reducing core loss.

[0034] Regarding the technical solution of this embodiment, such as Figure 2 and Figure 3 As shown, the annular cavity ferrite structure of this embodiment is simulated using the parameters of the high-frequency power ferrite material ML91S. As a specific implementation method, this structure is based on the optimization of the magnetic flux density distribution characteristics inside the solid magnetic core at a specific frequency. Specifically, this embodiment selects a magnetic core size with an outer diameter OD of 52mm, an inner diameter ID of 28mm, and a height H of 17mm, and under the condition of winding turns N=4, it is designed for... Figure 2 The solid magnetic core shown exhibits a high concentration of magnetic flux density at the center of its cross-section at the resonance point. Innovatively, this high-loss region at the center is physically removed, resulting in a structure resembling... Figure 3 The hollow rectangular cross-section structure shown has a preset wall thickness;

[0035] Specifically, this annular cavity ferrite structure possesses two aspects of performance regulation and optimization capabilities: firstly, it achieves significant loss suppression through cross-sectional hollowing design, such as... Figure 2 As shown, this structure forces the magnetic flux to redistribute to the outer and inner walls, disrupting the original standing wave mode. Simulation verification shows that compared to the high loss of 1010.6W for a solid magnetic core of the same size, the structure in this embodiment reduces the loss to 192W (a reduction of approximately 80%) and improves the quality factor Q by 35%. Secondly, by reducing the effective radial wall thickness, the bandwidth of the magnetic core application is extended, such as... Figure 4As shown in the comparison of normalized relative permeability, this structure shifts the resonant point of the magnetic core by about 13% towards higher frequencies by changing the critical physical size that determines electromagnetic wave oscillation. This adjustment capability ensures that the magnetic components can maintain stable permeability at higher MHz frequencies, thereby reducing the heating of high-frequency magnetic components, improving operating efficiency, and expanding the effective operating bandwidth, providing a reliable physical basis for high-frequency and high-power applications.

[0036] Example 2:

[0037] Referring to Figure 5, this embodiment provides another core structure considering dimensional resonance, aiming to demonstrate that the cavity proposed in this invention is also applicable to rectangular or polygonal closed magnetic circuit structures. This rectangular cavity ferrite structure can be assembled from four hollow linear magnetic blocks. This modular design significantly reduces the sintering difficulty of complex hollow structures, making it particularly suitable for constructing high-power, high-frequency transformer cores.

[0038] In summary, this invention, by innovatively employing a hollow rectangular cross-section design to fabricate annular cavity ferrite structures, successfully solves the problems of internal magnetic flux concentration and loss surge in annular magnetic cores under high-frequency excitation. It achieves physical optimization of high-frequency magnetic flux and eddy current paths, resulting in a significant reduction in high-frequency losses and an effective shift of the resonant point.

[0039] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0040] For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another element, it may be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0042] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A magnetic core considering size resonance, characterized in that: The magnetic core has an internal cavity, which is surrounded by a peripheral wall with a predetermined wall thickness, and the peripheral wall is made of magnetic material.

2. The magnetic core as described in claim 1, characterized in that: The cross-section of the cavity is rectangular, circular, or elliptical.

3. The magnetic core as described in claim 1, characterized in that: The magnetic core is a toroidal core, and the cavity is arranged through the circumferential path of the toroidal core, forming a closed annular channel inside the toroidal core.

4. The magnetic core as described in claim 3, characterized in that: The annular channel is filled with a cooling medium, an insulating and thermally conductive medium, or a non-magnetic material with low magnetic permeability.

5. The magnetic core as described in claim 1, characterized in that: The preset wall thickness is less than the critical size resonant thickness of the magnetic material at the operating frequency.

6. The magnetic core as described in claim 1, characterized in that: The cross-sectional area of ​​the cavity has a preset area ratio to the total cross-sectional area of ​​the magnetic core; the preset area ratio is configured to minimize the high-loss region inside the magnetic core while maintaining the inductance coefficient of the magnetic core to meet the design requirements.

7. The magnetic core as described in claim 1, characterized in that: The magnetic core includes several core units, each having a first end and a second end, and forming a hollow structure from the first end to the second end; the several core units are arranged end to end to form a closed magnetic core.

8. A magnetic element, characterized in that: It includes a magnetic core and at least one winding, the winding being wound around the magnetic core; the magnetic core is a magnetic core as described in any one of claims 1 to 7.

9. A transformer, characterized in that: Includes the magnetic element as described in claim 8.

10. An inductor, characterized in that: Includes the magnetic element as described in claim 8.

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