Method, system, medium and equipment for calculating magnetic flux density distribution of nanocrystalline iron core

Abstract

The invention discloses a method, a system, a medium and equipment for calculating magnetic flux density distribution in a nanocrystalline high-frequency transformer core under a load working condition, and the method comprises the steps: decomposing the magnetic flux density under the load working condition into superposition of the magnetic flux density under an open-circuit working condition and the magnetic flux density under a short-circuit working condition; the magnetic flux density distribution in the nanocrystalline iron core under the load working condition can be obtained by simulating the magnetic flux density in the nanocrystalline iron core under the open-circuit working condition and the short-circuit working condition only by adopting frequency domain finite element simulation and then performing superposition calculation. Time domain finite element simulation calculation is not needed, the simulation calculation time is greatly shortened, and the calculation efficiency is improved.

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 magnetic flux density distribution in an iron core of a nanocrystalline high-frequency transformer under load conditions. Background Art

[0002] The accurate calculation of the core loss of high-frequency transformers is of great significance for the efficiency evaluation and heat dissipation design of high-frequency transformers. Since the core loss density is closely related to the magnetic flux density, the accurate calculation of the magnetic flux density distribution in the core is the prerequisite for the accurate calculation of the core loss.

[0003] Finite element simulation methods can be used to calculate the magnetic flux density distribution in the core. For ferrite cores, since ferrite is a homogeneous material, its conductivity and permeability parameters have isotropic properties. In finite element simulation, the ferrite can be directly segmented using tetrahedral meshes. The nanocrystalline core is wound with strips, and its structure is a multi-layer 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. Refined mesh segmentation of each layer of strips and insulation layers will result in a large amount of model calculation. Therefore, the prior art proposes a homogenized finite element modeling method to equate the multi-layer composite nanocrystalline core to a homogeneous entity. The equivalent nanocrystalline core entity has anisotropic conductivity and permeability characteristics. The prior art performs frequency domain simulation on the magnetic flux density distribution in the nanocrystalline core under open circuit conditions based on the homogenization modeling method. Since the magnetic flux density distribution under open circuit conditions is relatively uniform, free tetrahedral meshing can be used. The prior art performs frequency domain simulation on the magnetic flux density distribution in the nanocrystalline core under short circuit conditions based on the homogenization modeling method. Since the magnetic flux density distribution under short circuit conditions is concentrated on the surface strip, it is necessary to perform a more refined meshing on the surface strip of the core. The simulation of the magnetic flux density distribution in the nanocrystalline core under load conditions based on the homogenization modeling method requires refined meshing and time domain simulation calculations, which requires huge calculations. At present, there is no relevant method that can accurately and efficiently calculate the magnetic flux density distribution in the nanocrystalline 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] A method for calculating the magnetic flux density distribution in the core of a nanocrystalline high-frequency transformer under a load condition of the present invention comprises:

[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 load Equal to the main magnetic flux φ under open circuit conditions main The 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] In the formula, 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] In the formula, and is the total flux linkage under open circuit and short circuit conditions, and the coefficient k 11 is the 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] In the formula, 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, firstly, 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 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 lamination structure, and the anisotropic magnetic permeability and electrical conductivity of the core are expressed as

[0035] ,

[0036] ,

[0037] In the formula, 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, and μ m is the magnetic permeability of the strip, σ m is the 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 through the cross section S of the nanocrystalline high-frequency transformer core under load conditions using the equivalent magnetizing voltage. load Equal to the main magnetic flux φ under open circuit conditions main The 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] In the formula, 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 cross section S of the core.

[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.

[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 calculation method of the magnetic flux density distribution in the nanocrystalline high-frequency transformer core 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. It only needs to use frequency domain finite element simulation to simulate the magnetic flux density in the nanocrystalline core under open circuit conditions and short circuit conditions, and then superimpose the calculation to obtain the magnetic flux density distribution in the nanocrystalline core under load conditions. There is no need to perform time domain finite element simulation calculation, which greatly reduces the simulation calculation time and improves the calculation 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 to enable those skilled in the art to 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 implementation methods 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 drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0059] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0060] In the attached picture:

[0061] Figure 1 The 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 DAB load condition of 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 is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination 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 creative work are 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 claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are 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 require further definition and explanation 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 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, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0070] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0071] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates 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 in conjunction with the accompanying drawings, and each of the accompanying drawings does 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] In the formula, 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 The 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] In the formula, 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] In the formula, and is the total flux linkage under open circuit and short circuit conditions, and the coefficient k 11 is the 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, firstly, 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 Calculated 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 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] In the formula, 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, and μ m is the magnetic permeability of the strip, σ m is the 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 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] In the formula, 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 A(t) and B(t) is shown in Figure 1 shown.

[0115] When the core is not saturated, the core magnetic permeability is approximately a constant value. According to the superposition principle, the magnetic flux φ inside the nanocrystalline core under load conditions load Equal to the main magnetic flux φ under open circuit conditions main The 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] In the formula, 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 high-order 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 the frequency is very small at low frequency, the magnetic permeability of the core can be approximately considered not to change with the frequency and is 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 the 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] In the formula, and is the total flux linkage under open circuit and short circuit conditions, k 11 is the 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 amplitude under open circuit and short circuit conditions.

[0145] Since the electrical conductivity and magnetic permeability of the nanocrystalline core are anisotropic, the homogenized finite element model can be used to calculate the magnetic flux density in the core. Figure 3 The homogenized solid body shown in the figure 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] In the formula, 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, and μ m is the magnetic permeability of the strip, σ m is the 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 DAB converter can be decomposed into the excitation voltage u AB The open circuit condition and excitation voltage are 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 through the cross section S of the nanocrystalline high-frequency transformer core under load conditions using the equivalent magnetizing voltage. load Equal to the main magnetic flux φ under open circuit conditions main The 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] In the formula, 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 cross section S of the core.

[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.

[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 are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the 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 load Equal to the main magnetic flux φ under open circuit conditions main The 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 ， ’ In the formula, 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: Preferably, when the area S of the core cross section S approaches zero, ， In the formula, and is the total flux linkage under open circuit and short circuit conditions, and the coefficient k 11 is the 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 ’ In the formula, 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 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 ， ， In the formula, 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, and μ m is the magnetic permeability of the strip, σ m is the 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: These include, The load measurement unit is used to characterize the average magnetic flux density through the cross section S of the nanocrystalline high-frequency transformer core under load conditions using the equivalent magnetizing voltage. load Equal to the main magnetic flux φ under open circuit conditions main The 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 ， ’ In the formula, 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 for calculating 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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