Nanocrystalline iron core magnetic flux density distribution calculation method, system, medium and equipment

Abstract

Disclosed are a method, system, medium, and device for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions. The method decomposes the magnetic flux density under load conditions into the superposition of the magnetic flux density under open-circuit conditions and the magnetic flux density under short-circuit conditions. Frequency-domain finite element simulation is performed on the magnetic flux density in the nanocrystalline core under open-circuit and short-circuit conditions, and then the superposition calculations are performed to obtain the magnetic flux density distribution in the nanocrystalline core under load conditions. This eliminates the need for time-domain finite element simulation, significantly reducing simulation time and improving computational efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocrystalline high-frequency transformers, and in particular to a method, system, medium and equipment for calculating the magnetic flux density distribution in the iron core of a nanocrystalline high-frequency transformer under load conditions. Background Art

[0002] Accurately calculating the core loss of a high-frequency transformer is crucial for efficiency evaluation and heat dissipation design. Since core loss density is closely related to magnetic flux density, accurately calculating the magnetic flux density distribution within the core is a prerequisite for accurate calculation of core loss.

[0003] Finite element simulation methods can be used to calculate the magnetic flux density distribution in the iron core. For ferrite cores, since ferrite is a homogeneous material, its electrical conductivity and magnetic permeability parameters are isotropic. Therefore, the ferrite can be directly segmented using tetrahedral meshes during finite element simulation. Nanocrystalline cores are made of wound strips. Their structure is a multilayer composite structure consisting of nanocrystalline strips and epoxy resin insulation layers. The thickness of the nanocrystalline strips and epoxy resin insulation layers is extremely small. Fine meshing of each layer of strip and insulation layer will result in a large amount of model calculation. Therefore, the existing technology proposes a homogenized finite element modeling method to equate the multilayer composite nanocrystalline core to a homogeneous entity. The equivalent nanocrystalline core entity has anisotropic electrical conductivity and magnetic permeability characteristics. The existing technology uses a homogenized modeling method to perform frequency domain simulation of the magnetic flux density distribution in the nanocrystalline iron core under open circuit conditions. Since the magnetic flux density distribution under open circuit conditions is relatively uniform, free tetrahedral meshing can be used. The existing technology uses a homogenized modeling method to perform frequency domain simulation of the magnetic flux density distribution in the nanocrystalline iron core under short circuit conditions. Since the magnetic flux density distribution under short circuit conditions is concentrated on the surface strip, a more refined meshing of the core surface strip is required. Simulating the magnetic flux density distribution in the nanocrystalline iron core under load conditions based on the homogenized modeling method requires refined meshing and time domain simulation calculations, which are computationally intensive. Currently, there is no relevant method that can accurately and efficiently calculate the magnetic flux density distribution in the nanocrystalline iron core under load conditions.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method, system, medium and equipment for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions, so as to accurately and efficiently obtain the magnetic flux density of the nanocrystalline core under load conditions.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions, comprising:

[0008] Under load conditions, the equivalent magnetizing voltage is used to characterize the average magnetic flux density through the cross section S of the nanocrystalline high-frequency transformer core. The magnetic flux φ inside the nanocrystalline core under load conditions is load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of , EMVu of a certain section S of nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of

[0009] ;

[0010] Based on the Fourier superposition principle, the open circuit voltage u open and short-circuit voltage u short Expressed as

[0011] ,

[0012] Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage, and EMVu is the nth harmonic component of the open-circuit voltage under excitation. m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n Expressed as , , where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. The EMV under open-circuit and short-circuit conditions is expressed as

[0013] ,

[0014] ,

[0015] The EMV of the internal section S of the nanocrystalline core under load conditions is expressed as

[0016] ;

[0017] Through integration operation, the average magnetic flux density in the core cross section S is expressed as

[0018] .

[0019] In the method described, when the area S of the core cross section S approaches zero,

[0020] ,

[0021] Where, and is the total flux linkage under open circuit and short circuit conditions, and the coefficient k 11 It is a coefficient related to the main magnetic flux density distribution inside the core under open circuit sinusoidal excitation. The coefficient k 22 It is a coefficient related to the leakage flux density distribution inside the core under short-circuit sinusoidal excitation.

[0022] In the method described, the equivalent magnetizing voltage EMV is

[0023]

[0024] Where u m (t) is the equivalent magnetizing voltage of the core section S, φ(t) is the magnetic flux passing through the section, B(t) is the magnetic flux density, B ave (t) is the average magnetic flux density in the cross section, and S is the area of ​​the core cross section S.

[0025] In the method described, the coefficients k1, k2, k 11 and k 22 Through finite element simulation, first, the frequency domain simulation is used to calculate the magnetic flux density distribution in the nanocrystalline core under open circuit and short circuit conditions, and then the amplitude U of the equivalent magnetizing voltage EMV of the core section is calculated. m ,

[0026] ,

[0027] Where f is the frequency, φ m is the magnetic flux amplitude, B m is the magnetic flux density amplitude, S is the area of ​​the core cross section,

[0028] Finally, k1, k2, k 11 and k 22 for:

[0029] ,

[0030] ,

[0031] ,

[0032] ,

[0033] Where Um,open and U m,short is the EMV amplitude calculated under open circuit and short circuit conditions, B m,open and B m,short is the magnetic flux density amplitude calculated under open circuit and short circuit conditions, U sin,open and U sin,short is the open-circuit and short-circuit excitation voltage amplitude, and is the flux linkage amplitude under open circuit and short circuit conditions.

[0034] In the method described, a homogenized solid entity is used to model the nanocrystalline core instead of a layered laminate structure, and the anisotropic magnetic permeability and electrical conductivity of the core are expressed as

[0035] ,

[0036] ,

[0037] Where μ r 、μ d and μ n are the equivalent magnetic permeabilities of the nanocrystalline core in the winding direction, thickness direction and normal direction, σ r , σ d and σ n are the equivalent conductivity of the nanocrystalline core in the winding direction, thickness direction and normal direction respectively, F is the filling factor, μ0 is the magnetic permeability in vacuum, μ m is the magnetic permeability of the strip, σ m is the electrical conductivity of the strip, d is the strip thickness, and D is the core width.

[0038] A system for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions includes:

[0039] The load measurement unit is used to characterize the average magnetic flux density of the cross section S of the nanocrystalline high-frequency transformer core under load conditions using the equivalent magnetizing voltage. The magnetic flux φ inside the nanocrystalline core under load conditions load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of , EMVu of a certain section S of nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of ;

[0040] Voltage calculation unit, which calculates the open circuit voltage u based on the Fourier superposition principle open and short-circuit voltage ushort , open circuit voltage u open and short-circuit voltage u short Expressed as

[0041] ,

[0042] Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage, and EMVu is the nth harmonic component of the open-circuit voltage under excitation. m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n Expressed as , , where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. The EMV under open-circuit and short-circuit conditions is expressed as

[0043] ,

[0044] ,

[0045] The EMV of the internal section S of the nanocrystalline core under load conditions is expressed as

[0046] ;

[0047] Integral unit, through the integration operation, the average magnetic flux density in the core section S is expressed as

[0048] .

[0049] In the system, the integration unit includes a finite element simulation unit for calculating the average magnetic flux density in the core cross section S.

[0050] In the system, the finite element simulation unit is COMSOL Multiphysics, Ansys or Maxwell.

[0051] A computer storage medium includes computer instructions, which, when executed on a computer, cause the computer to execute the method described above.

[0052] An electronic device, comprising:

[0053] A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein:

[0054] When the processor executes the program, the method described is implemented.

[0055] Beneficial effects

[0056] The method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions decomposes the magnetic flux density under load conditions into the superposition of the magnetic flux density under open-circuit conditions and the magnetic flux density under short-circuit conditions. Simply using frequency-domain finite element simulation to simulate the magnetic flux density in the nanocrystalline core under open-circuit and short-circuit conditions, and then superimposing the calculations, the magnetic flux density distribution in the nanocrystalline core under load conditions can be obtained. This eliminates the need for time-domain finite element simulation, significantly reducing simulation time and improving computational efficiency.

[0057] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and easier to understand, so that those skilled in the art can implement it according to the contents of the specification, and to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described below by way of example. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0059] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0060] In the attached figure:

[0061] Figure 1 The present invention provides a method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions. m Schematic diagram of the time domain waveforms of A(t) and B(t);

[0062] Figure 2 A schematic diagram of the steps of a method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions provided by the present invention;

[0063] Figure 3A schematic diagram of a nanocrystalline core homogenization model for calculating the magnetic flux density distribution in a nanocrystalline high-frequency transformer core under load conditions provided by the present invention;

[0064] Figure 4 A schematic diagram of the EMV and magnetic flux density calculation process under a single-phase shift DAB load condition for a method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under a load condition provided by the present invention.

[0065] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0066] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0067] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0068] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0069] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0071] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to direct connection or indirect connection through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0072] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0073] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0074] In one embodiment, if Figures 1 to 4 As shown, the present disclosure provides a method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions, comprising the following steps:

[0075] Under load conditions, the equivalent magnetizing voltage is used to characterize the average magnetic flux density through the cross section S of the nanocrystalline high-frequency transformer core. The equivalent magnetizing voltage EMV is

[0076] (1)

[0077] Where u m (t) is the equivalent magnetizing voltage of the core section S, φ(t) is the magnetic flux passing through the section, B(t) is the magnetic flux density, B ave (t) is the average magnetic flux density in the cross section, S is the area of ​​the core cross section S;

[0078] Magnetic flux φ inside the nanocrystalline core under load conditions load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of

[0079] (2)

[0080] EMVu of a certain section S of nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of

[0081] (3)

[0082] Based on the Fourier superposition principle, the open circuit voltage u open and short-circuit voltage u short Expressed as

[0083] (4)

[0084] (5)

[0085] Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage, and EMVu is the nth harmonic component of the open-circuit voltage under excitation. m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n Expressed as

[0086] (6)

[0087] (7)

[0088] Where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. Combining formulas (4)-(7), the EMV under open-circuit and short-circuit conditions is expressed as

[0089] (8)

[0090] (9)

[0091] Combining formulas (3), (8) and (9), the EMV of the internal section S of the nanocrystalline core under load conditions is expressed as

[0092] (10);

[0093] Through integration operation, the average magnetic flux density in the core cross section S is expressed as

[0094] (11)

[0095] When the area S of the core cross section S approaches zero, formula (11) becomes

[0096] (12)

[0097] Where, and is the total flux linkage under open circuit and short circuit conditions, and the coefficient k 11 It is a coefficient related to the main magnetic flux density distribution inside the core under open circuit sinusoidal excitation. The coefficient k 22 It is a coefficient related to the leakage flux density distribution inside the core under short-circuit sinusoidal excitation.

[0098] In a preferred embodiment of the method, the coefficients k1, k2, k 11 and k 22 Through finite element simulation, first, the frequency domain simulation is used to calculate the magnetic flux density distribution in the nanocrystalline core under open circuit and short circuit conditions. Then, the amplitude U of the equivalent magnetizing voltage EMV of the core section is calculated by formula (13): m ,

[0099] (13)

[0100] Where f is the frequency, φ m is the magnetic flux amplitude, B m is the magnetic flux density amplitude, S is the area of ​​the core cross section,

[0101] Finally, k1, k2, k 11 and k 22 Calculate using formulas (14)-(17).

[0102] (14)

[0103] (15)

[0104] (16)

[0105] (17)

[0106] Where U m,open and U m,short is the EMV amplitude calculated under open circuit and short circuit conditions, B m,open and B m,shortis the magnetic flux density amplitude calculated under open circuit and short circuit conditions, U sin,open and U sin,short is the open-circuit and short-circuit excitation voltage amplitude, and is the flux linkage amplitude under open circuit and short circuit conditions.

[0107] In a preferred embodiment of the method, a homogenized solid entity is used to model the nanocrystalline core instead of a layered laminate structure, and the anisotropic magnetic permeability and electrical conductivity of the core are expressed as

[0108] (18)

[0109] (19)

[0110] Where μ r 、μ d and μ n are the equivalent magnetic permeabilities of the nanocrystalline core in the winding direction, thickness direction and normal direction, σ r , σ d and σ n are the equivalent conductivity of the nanocrystalline core in the winding direction, thickness direction and normal direction respectively, F is the filling factor, μ0 is the magnetic permeability in vacuum, μ m is the magnetic permeability of the strip, σ m is the electrical conductivity of the strip, d is the strip thickness, and D is the core width.

[0111] In a preferred embodiment of the method, the finite element simulation is performed by COMSOL Multiphysics, Ansys or Maxwell.

[0112] In one embodiment, since the magnetic flux density cannot be measured directly, based on Faraday's law of electromagnetic induction, an equivalent magnetization voltage (EMV) is proposed to characterize the average magnetic flux density passing through a certain cross section of the core. The equivalent magnetization voltage EMV is defined as

[0113] (1)

[0114] Where u m (t) is the equivalent magnetizing voltage of the core section S, φ(t) is the magnetic flux passing through the section, B(t) is the magnetic flux density, B ave (t) is the average magnetic flux density in the cross section. m The time domain waveform diagram of B(t) and B(t) is shown in Figure 1 shown.

[0115] When the core is not saturated, the core magnetic permeability is approximately constant. According to the superposition principle, the magnetic flux φ inside the nanocrystalline core under load conditions is load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of

[0116] (2)

[0117] Based on formula (1), the EMVu of a certain section of the nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of

[0118] (3)

[0119] Based on the Fourier superposition principle, the open circuit voltage u open and short-circuit voltage u short It can be expressed as

[0120] (4)

[0121] (5)

[0122] Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage. Since the amplitude of the higher harmonic components of the open-circuit voltage and the short-circuit voltage is very small and the change of the magnetic permeability of the nanocrystalline strip with frequency at low frequency is very small, the magnetic permeability of the core can be approximately considered to be unchanged with frequency and the same as the magnetic permeability of the core at the fundamental frequency. Therefore, the magnetic flux distribution inside the nanocrystalline core does not change with frequency. The magnetic flux distribution inside the nanocrystalline core under non-sinusoidal excitation is the same as that under fundamental frequency sinusoidal excitation. Therefore, EMVu under the nth harmonic excitation of the open-circuit voltage is m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n It can be expressed as

[0123] (6)

[0124] (7)

[0125] Where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. Combining formulas (4)-(7), the EMV under open-circuit and short-circuit conditions can be expressed as

[0126] (8)

[0127] (9)

[0128] Combining formulas (3), (8) and (9), the EMV of a certain cross section inside the nanocrystalline core under load conditions can be expressed as

[0129] (10)

[0130] By integral operation or the inverse operation of formula (1), the average magnetic flux density in the core cross section can be expressed as

[0131] (11)

[0132] When S approaches zero, formula (11) becomes

[0133] (12)

[0134] Where, and is the total flux linkage under open circuit and short circuit conditions, k 11 is a coefficient related to the main magnetic flux density distribution inside the core under open circuit sinusoidal excitation, k 22 It is a coefficient related to the leakage flux density distribution inside the core under short-circuit sinusoidal excitation.

[0135] A simplified flowchart of the method is shown in Figure 2 shown.

[0136] Coefficients k1, k2, k 11 and k 22 It can be calculated by finite element simulation. First, the frequency domain simulation is used to calculate the magnetic flux density distribution in the nanocrystalline core under open circuit and short circuit conditions. Then, the equivalent magnetizing voltage (EMV) amplitude U of the core section is calculated by formula (13): m ,

[0137] (13)

[0138] Where f is the frequency, φ m is the magnetic flux amplitude, B m is the magnetic flux density amplitude, and S is the area of ​​the core cross section.

[0139] Finally, k1, k2, k 11 and k 22 It can be calculated using formulas (14)-(17).

[0140] (14)

[0141] (15)

[0142] (16)

[0143] (17)

[0144] Where U m,open and U m,short is the EMV amplitude calculated under open circuit and short circuit conditions, B m,open and B m,short is the magnetic flux density amplitude calculated under open circuit and short circuit conditions, U sin,open and U sin,short is the open-circuit and short-circuit excitation voltage amplitude, and is the flux linkage amplitude under open circuit and short circuit conditions.

[0145] Since the electrical conductivity and magnetic permeability of the nanocrystalline core are anisotropic, a homogenized finite element model can be used to calculate the magnetic flux density in the core. Figure 3 The homogenized solid body shown here replaces the layered lamination structure to model the nanocrystalline core. The anisotropic magnetic permeability and electrical conductivity of the core can be expressed as

[0146] (18)

[0147] (19)

[0148] Where μ r 、μ d and μ n are the equivalent magnetic permeabilities of the nanocrystalline core in the winding direction, thickness direction and normal direction, σ r , σ d and σ n are the equivalent conductivity of the nanocrystalline core in the winding direction, thickness direction and normal direction respectively, F is the filling factor, μ0 is the magnetic permeability in vacuum, μ m is the magnetic permeability of the strip, σ m is the electrical conductivity of the strip, d is the strip thickness, and D is the core width.

[0149] The specific implementation steps of the above method are analyzed by taking the single-phase-shifted dual-active-bridge (DAB) converter as an example. Figure 4 The calculation process of EMV and magnetic flux density distribution of nanocrystalline core based on superposition principle is shown. The primary and secondary voltages of the transformer are u AB and u CD The load condition of the single-phase-shifted DAB converter can be decomposed into the excitation voltage u AB The open circuit condition and excitation voltage is u AB-u CD According to the superposition principle, the EMV of the core section under load conditions is equal to the sum of the EMV of the core section under open circuit conditions and the EMV of the core section under short circuit conditions. Based on formula (10), the EMV of the core section under load conditions can be expressed as

[0150] (20)

[0151] Through finite element simulation calculation and formulas (11) and (12), the average magnetic flux density of each cross section of the core and the magnetic flux density distribution in the core can be calculated.

[0152] A system for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions includes:

[0153] The load measurement unit is used to characterize the average magnetic flux density of the cross section S of the nanocrystalline high-frequency transformer core under load conditions using the equivalent magnetizing voltage. The magnetic flux φ inside the nanocrystalline core under load conditions load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of , EMVu of a certain section S of nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of ;

[0154] Voltage calculation unit, which calculates the open circuit voltage u based on the Fourier superposition principle open and short-circuit voltage u short , open circuit voltage u open and short-circuit voltage u short Expressed as

[0155] ,

[0156] Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage, and EMVu is the nth harmonic component of the open-circuit voltage under excitation. m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n Expressed as , , where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. The EMV under open-circuit and short-circuit conditions is expressed as

[0157] ,

[0158] ,

[0159] The EMV of the internal section S of the nanocrystalline core under load conditions is expressed as

[0160] ;

[0161] Integral unit, through the integration operation, the average magnetic flux density in the core section S is expressed as

[0162] .

[0163] In the system, the integration unit includes a finite element simulation unit for calculating the average magnetic flux density in the core cross section S.

[0164] In the system, the finite element simulation unit is COMSOL Multiphysics, Ansys or Maxwell.

[0165] A computer storage medium includes computer instructions, which, when executed on a computer, cause the computer to execute the method described above.

[0166] An electronic device, comprising:

[0167] A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein:

[0168] When the processor executes the program, the method described is implemented.

[0169] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.

Claims

1. A method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions, characterized in that: It includes the following steps: Under load conditions, the equivalent magnetizing voltage is used to characterize the average magnetic flux density through the cross section S of the nanocrystalline high-frequency transformer core. The magnetic flux φ inside the nanocrystalline core under load conditions is load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of , EMVu of a certain section S of nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of ； Based on the Fourier superposition principle, the open circuit voltage u open and short-circuit voltage u short Expressed as ， ’ Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage, and EMVu is the nth harmonic component of the open-circuit voltage under excitation. m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n Expressed as , , where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. The EMV under open-circuit and short-circuit conditions is expressed as ， ， The EMV of the internal section S of the nanocrystalline core under load conditions is expressed as ； Through integration operation, the average magnetic flux density in the core cross section S is expressed as 。 2. The method according to claim 1, characterized in that When the area S of the core cross section S approaches zero, ， Where, and is the total flux linkage under open circuit and short circuit conditions, and the coefficient k 11 It is a coefficient related to the main magnetic flux density distribution inside the core under open circuit sinusoidal excitation. The coefficient k 22 It is a coefficient related to the leakage flux density distribution inside the core under short-circuit sinusoidal excitation.

3. The method according to claim 1, characterized in that The equivalent magnetizing voltage EMV is ’ Where u m (t) is the equivalent magnetizing voltage of the core section S, φ(t) is the magnetic flux passing through the section, B(t) is the magnetic flux density, B ave (t) is the average magnetic flux density in the cross section, and S is the area of ​​the core cross section S.

4. The method according to claim 3, characterized in that Coefficients k1, k2, k 11 and k 22 Through finite element simulation, first, the frequency domain simulation is used to calculate the magnetic flux density distribution in the nanocrystalline core under open circuit and short circuit conditions, and then the amplitude U of the equivalent magnetizing voltage EMV of the core section is calculated. m , ， Where f is the frequency, φ m is the magnetic flux amplitude, B m is the magnetic flux density amplitude, S is the area of ​​the core cross section, Finally, k1, k2, k 11 and k 22 for: ， ， ， ， Where U m,open and U m,short is the EMV amplitude calculated under open circuit and short circuit conditions, B m,open and B m,short is the magnetic flux density amplitude calculated under open circuit and short circuit conditions, U sin,open and U sin,short is the open-circuit and short-circuit excitation voltage amplitude, and is the flux linkage amplitude under open circuit and short circuit conditions.

5. The method according to claim 1, characterized in that The nanocrystalline core is modeled by homogenizing solid entities instead of layered laminations. The anisotropic magnetic permeability and electrical conductivity of the core are expressed as ， ， Where μ r 、μ d and μ n are the equivalent magnetic permeabilities of the nanocrystalline core in the winding direction, thickness direction and normal direction, σ r , σ d and σ n are the equivalent conductivity of the nanocrystalline core in the winding direction, thickness direction and normal direction respectively, F is the filling factor, μ0 is the magnetic permeability in vacuum, μ m is the magnetic permeability of the strip, σ m is the electrical conductivity of the strip, d is the strip thickness, and D is the core width.

6. A system for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under load conditions, characterized in that: It includes, The load measurement unit is used to characterize the average magnetic flux density of the cross section S of the nanocrystalline high-frequency transformer core under load conditions using the equivalent magnetizing voltage. The magnetic flux φ inside the nanocrystalline core under load conditions load Equal to the main magnetic flux φ under open circuit conditions main Leakage flux φ under short-circuit conditions leakage The sum of , EMVu of a certain section S of nanocrystalline core under load conditions m,load Equal to the EMVu of the cross section under open circuit conditions m,open EMVu of the cross section under short circuit conditions m,short The sum of ; Voltage calculation unit, which calculates the open circuit voltage u based on the Fourier superposition principle open and short-circuit voltage u short , open circuit voltage u open and short-circuit voltage u short Expressed as ， ’ Where u open,sin,n is the nth harmonic component of the open circuit voltage, u short,sin,n is the nth harmonic component of the short-circuit voltage, and EMVu is the nth harmonic component of the open-circuit voltage under excitation. m,open,n And EMVu under the nth harmonic excitation of short-circuit voltage m,short,n Expressed as , , where k1 is the coefficient related to the main magnetic flux distribution inside the core under open-circuit sinusoidal excitation, and k2 is the coefficient related to the leakage magnetic flux distribution inside the core under short-circuit sinusoidal excitation. The EMV under open-circuit and short-circuit conditions is expressed as ， ， The EMV of the internal section S of the nanocrystalline core under load conditions is expressed as ； Integral unit, through the integration operation, the average magnetic flux density in the core section S is expressed as 。 7. The system according to claim 6, characterized in that The integration unit includes a finite element simulation unit that calculates the average magnetic flux density within the core cross section S.

8. The system according to claim 7, characterized in that The finite element simulation unit is COMSOL Multiphysics, Ansys or Maxwell.

9. A computer storage medium, characterized in that The storage medium includes computer instructions, which, when executed on a computer, enable the computer to execute the method according to any one of claims 1 to 5.

10. An electronic device, characterized in that: The electronic device comprises: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method according to any one of claims 1 to 5 is implemented.

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