A three-dimensional thermal network modeling method of high-frequency transformer considering heat transfer mechanism

Abstract

The application discloses a kind of high-frequency transformer three-dimensional thermal network modeling methods considering heat transfer mechanism, belong to high-frequency transformer technical field, including the following steps: S1, construct high-frequency transformer finite element model and carry out magnetic-thermal coupling simulation;S2, the division of node area is carried out to the core and winding of high-frequency transformer;S3, for different node areas, calculate the thermal resistance of high-frequency transformer 3D geometric model;S4, according to the simulation result of S1, construct heat conduction thermal resistance, convection heat transfer thermal resistance and radiation heat transfer thermal resistance;S5, based on heat flow source, heat conduction thermal resistance, convection heat transfer thermal resistance, radiation thermal resistance, heat capacity and environment node temperature, establish complete high-frequency transformer 3D thermal network model.The application uses the above method, by introducing convection and radiation heat transfer mechanism, and combining refined heat source division and thermal resistance calculation, can improve the precision of high-frequency transformer temperature rise prediction while maintaining high computational efficiency.

Description

Technical Field

[0001] This invention relates to the field of high-frequency transformer technology, and in particular to a three-dimensional thermal network modeling method for high-frequency transformers that takes into account heat transfer mechanisms. Background Technology

[0002] High-frequency transformers are a crucial component of modern power electronic equipment, widely used in power conversion, power conversion, and other fields. As the application of high-frequency transformers in high-frequency power transmission continues to expand, the requirements for high efficiency and precise control are also increasing. Temperature rise prediction of transformers is one of the key technologies to ensure their safe and stable operation. However, existing high-frequency transformer thermal network models often have some shortcomings, particularly in the accurate prediction of temperature distribution.

[0003] Traditional high-frequency transformer thermal network modeling methods primarily focus on heat conduction models, neglecting the influence of convection and radiation heat transfer. This leads to low accuracy in temperature rise predictions under complex operating conditions. Particularly on the surface of high-frequency transformers, the contribution of radiation and convection heat transfer mechanisms to heat dissipation gradually increases with the rise in operating temperature; therefore, ignoring these factors affects the accuracy of thermal predictions. Furthermore, existing models typically employ simplified heat source partitioning methods, making it impossible to accurately reflect actual loss distribution and temperature rise predictions under complex spatial layouts.

[0004] Currently, while some methods attempt to combine finite element analysis for thermal field simulation and optimization, these methods typically require long computation times and high computational costs. Due to the complexity of finite element models, many methods are not easily implemented in practical engineering, especially in situations requiring real-time prediction and optimization, where computational efficiency becomes a limiting factor. Therefore, accurately predicting the temperature rise of high-frequency transformers under complex operating conditions while ensuring computational efficiency has become a challenge in current research. Summary of the Invention

[0005] The purpose of this invention is to provide a three-dimensional thermal network modeling method for high-frequency transformers that considers heat transfer mechanisms. This method aims to address the problem that existing high-frequency transformer thermal network models neglect the coupling effects of convection and radiation during temperature rise prediction, resulting in insufficient accuracy in temperature distribution calculation. By introducing realistic convection and radiation heat transfer coefficients and combining them with refined node partitioning and thermal resistance calculation, high-precision and high-efficiency steady-state temperature rise prediction is achieved.

[0006] To achieve the above objectives, this invention provides a method for modeling a three-dimensional thermal network of a high-frequency transformer that considers the heat transfer mechanism, comprising the following steps:

[0007] S1. Construct a finite element model of a high-frequency transformer and perform magnetothermal coupling simulation;

[0008] S2. Divide the core and windings of the high-frequency transformer into nodal regions;

[0009] S3. Calculate the thermal resistance of the 3D geometric model of the high-frequency transformer for different node regions;

[0010] S4. Based on the simulation results of S1, construct the thermal resistance for heat conduction, heat transfer, and heat radiation.

[0011] S5. Based on the heat source, thermal conduction resistance, convective thermal resistance, radiative thermal resistance, heat capacity, and ambient node temperature, a complete 3D thermal network model of a high-frequency transformer is established.

[0012] Preferably, step S1 specifically involves: establishing a finite element model of the high-frequency transformer based on the actual topology and electrical design parameters of the high-frequency transformer, and performing a physical field simulation of the high-frequency transformer using magnetothermal bidirectional coupling to extract the loss distribution and surface temperature of the high-frequency transformer; performing bidirectional iterative solution of the loss and temperature fields through magnetothermal coupling, considering the nonlinear hysteresis characteristics of the core and the skin and proximity effect losses of the conductor, to ensure the physical accuracy of the initial loss distribution, and extracting the loss distribution and surface temperature to provide data for thermal network modeling.

[0013] Preferably, step S2 specifically involves: dividing the iron core into 7 regions along the geometric structure according to the spatial position and loss distribution of the iron core and windings, and dividing the primary and secondary windings into 8 regions along the four radial directions, thus constructing a total of 15 heat source nodes; the heating power of each heat source node is taken from the copper loss or iron loss of the corresponding region in the simulation results of step S1, and converted into a quantitative heat flow source input to the heat network; based on simulation analysis, the loss values ​​of each region of the iron core and windings are extracted.

[0014] Preferably, step S3 specifically involves: for regions with different geometric shapes, using the equivalent method of cuboid units and arc units, calculating the thermal resistance in three dimensions, and obtaining the equivalent thermal resistance network of the core, winding, and epoxy resin in the X, Y, and Z directions; the corner part of the core is an arc unit, the yoke of the core is a cuboid unit, and the winding is considered to be a cuboid unit.

[0015] Preferably, in step S3, for the cuboid element, the thermal resistance in the three directions is calculated by the following equation:

[0016] ;

[0017] ;

[0018] ;

[0019] in, , and These represent the thermal resistances of the cuboid unit in three directions, respectively. , and Respectively, they are cuboid units , y and z Length in the direction, , and Respectively, the cuboid unit material in x , y and z Thermal conductivity in the direction of direction.

[0020] Preferably, in step S3, for the arc-shaped unit, the thermal resistance in both radial directions is expressed as:

[0021] ;

[0022] ;

[0023] in, and Thermal resistance in the radial directions of the arc-shaped unit. Indicates the angle of the arc-shaped unit. Represents arc-shaped unit x Thermal conductivity in the direction, This represents the inner radius of the arc-shaped element. Indicates the outer radius of the arc-shaped unit;

[0024] For arc-shaped elements, the thermal resistance in the circumferential direction R X , R Y Represented as:

[0025] ;

[0026] in, Represents arc-shaped unit y Thermal conductivity in the direction of direction;

[0027] For arc-shaped units, the axial thermal resistance R Z Represented as:

[0028] ;

[0029] in, Represents arc-shaped unit y Thermal conductivity in the direction of direction.

[0030] Preferably, in step S4, the heat conduction between the internal components of the high-frequency transformer is calculated using the following thermal equation:

[0031] ;

[0032] in, It is the heat conducted between the internal components of the high-frequency transformer. It is the thermal conductivity of the material. A s It is the cross-sectional area perpendicular to the heat transfer direction, Δ T It is the temperature difference between objects. Indicates the path length in the direction of heat transfer;

[0033] Thermal conduction and thermal resistance R t It can be represented by the following expression:

[0034] ;

[0035] in, It is the path length in the heat transfer direction.

[0036] Preferably, in step S4, the convective heat transfer between the epoxy resin surface and the air on the surface of the high-frequency transformer is represented by the following equation:

[0037] ;

[0038] in, It is the heat transferred by convection between the epoxy resin surface and the air. h c It is the convective heat transfer coefficient on the surface of the high-frequency transformer. T s It is the surface temperature of the high-frequency transformer. Indicates ambient temperature;

[0039] Convection heat transfer thermal resistance R c It is represented by the following expression:

[0040] ;

[0041] The convective heat flux density of the epoxy resin surface and the temperature difference between the surface and the environment in the temperature field of the finite element model are extracted to calculate the convective heat transfer coefficient of the high-frequency transformer surface.

[0042] ;

[0043] in, q c Δ represents the convective heat flux density on the surface of the epoxy resin. T This indicates the temperature difference between the epoxy resin surface and the environment.

[0044] Preferably, in step S4, the radiative heat transfer between the epoxy resin surface of the high-frequency transformer and the ambient air is calculated using the following thermal equation:

[0045] ;

[0046] in, Q r It refers to the radiative heat transfer between the epoxy resin surface of the high-frequency transformer and the ambient air. h r It is the radiative heat transfer coefficient between the epoxy resin surface of the high-frequency transformer and the ambient air. T s It is the temperature of the epoxy resin surface of the high-frequency transformer;

[0047] Radiative heat transfer thermal resistance R r It is represented by the following expression:

[0048] ;

[0049] Temperature of epoxy resin surface in temperature field extracted based on finite element analysis T s Calculate the radiative heat transfer coefficient of the surface of the high-frequency transformer:

[0050] ;

[0051] in, σ It is Boltzmann's constant. σ =5.67×10 -8 W / (m 2 ×K 4 ), ε It is the radiation coefficient. ε =0.8.

[0052] Therefore, the above-mentioned method for modeling a three-dimensional thermal network of a high-frequency transformer that considers the heat transfer mechanism has the following beneficial effects:

[0053] (1) It not only considers the three heat transfer modes of heat conduction, convection and radiation, but also reflects the spatial distribution of losses in the core and winding through refined heat source division, which further improves the accuracy and applicability of the thermal model.

[0054] (2) By calculating the thermal resistance of cuboid and arc-shaped elements, the three-dimensional heat conduction model can be generated quickly, which solves the problem of difficult mesh refinement in traditional finite element methods. In addition, the modular modeling method adopted effectively improves the calculation efficiency and reduces the development cycle, which can better meet the dual requirements of temperature rise prediction accuracy and calculation efficiency in engineering applications.

[0055] (3) Taking into account the heat conduction, convection and radiation heat transfer mechanisms, the prediction accuracy of the internal temperature rise of high frequency transformers is significantly improved by introducing real convection and radiation heat transfer coefficients. The optimized thermal network model controls the node temperature rise error within ±5%, which greatly improves the accuracy and reliability of the prediction results and is particularly suitable for temperature simulation under complex working conditions.

[0056] (4) By dividing the heat source into 15 nodes, the spatial distribution of losses in the iron core and windings is accurately reflected, avoiding the errors caused by oversimplification in the traditional heat network model, ensuring higher accuracy of heat source distribution, more accurate prediction of heat flow in variable working environments, and further improving the applicability and accuracy of the model.

[0057] (5) A method for equivalent thermal resistance of cuboid and arc-shaped elements is proposed, which can quickly generate thermal resistance parameters and perform analysis without repeatedly refining the finite element mesh, greatly improving the calculation efficiency and making the establishment and iteration of the thermal network model more convenient and efficient, greatly shortening the development cycle, and is particularly suitable for engineering applications that require rapid response.

[0058] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0059] Figure 1 This is a flowchart of a three-dimensional thermal network modeling method for high-frequency transformers that considers heat transfer mechanisms, according to an embodiment of the present invention.

[0060] Figure 2 This is a node distribution diagram of the high-frequency transformer 3D thermal network model according to an embodiment of the present invention;

[0061] Figure 3 This is an equivalent heat network structure diagram of the cuboid and arc-shaped elements according to an embodiment of the present invention;

[0062] Figure 4 This is a distribution diagram of the convective and radiative heat transfer coefficients of the inner and outer surfaces of the epoxy resin in an embodiment of the present invention.

[0063] Figure 5 This is a complete 3D thermal network model structure diagram of a high-frequency transformer according to an embodiment of the present invention. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. 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 claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0065] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0066] Example:

[0067] like Figure 1 As shown, this invention provides a three-dimensional thermal network modeling method for high-frequency transformers that considers heat transfer mechanisms, including the following steps:

[0068] S1. Construct a finite element model of a high-frequency transformer and perform magnetothermal coupling simulation.

[0069] Based on the topology and electrical design parameters of an actual high-frequency transformer, a finite element model of the high-frequency transformer is established. In this embodiment, the high-frequency transformer also employs epoxy resin casting technology to achieve uniform heat dissipation and improve electrical insulation and thermal conductivity. Table 1 shows the electrical design parameters of the high-frequency transformer in this embodiment.

[0070] Table 1 Electrical Design Parameters of High-Frequency Transformers

[0071] ;

[0072] A magnetothermal bidirectional coupling physical field simulation of a high-frequency transformer was performed using Ansys software to extract the loss distribution and surface temperature of the transformer. The loss and temperature fields were solved iteratively through magnetothermal coupling, taking into account the nonlinear hysteresis characteristics of the core and the skin and proximity effects of the conductors to ensure the physical accuracy of the initial loss distribution. The loss distribution and surface temperature were then extracted to provide data for thermal network modeling.

[0073] S2. Divide the core and windings of the high-frequency transformer into node regions.

[0074] To construct an accurate 3D thermal network model, based on the spatial location and loss distribution of the core and windings, the core was divided into 7 regions along its geometric structure, and the primary and secondary windings were divided into 8 regions along the four radial directions, resulting in a total of 15 heat source nodes. This was done to capture the spatial distribution characteristics of losses and temperature, referencing... Figure 2 The heating power of each heat source node is taken from the copper loss or iron loss of the corresponding region in the simulation results of S1, and converted into a quantitative heat flow source input to the heat network. Based on the simulation analysis, the loss values ​​of each region of the iron core and winding are extracted. The specific results are shown in Table 2.

[0075] Table 2 Loss distribution of each sub-region of the core and windings of a high-frequency transformer

[0076] ;

[0077] S3. For different node regions, calculate the thermal resistance of the 3D geometric model of the high-frequency transformer. Specifically, for regions with different geometric shapes, use the equivalent method of cuboid and arc unit to calculate the thermal resistance in three dimensions, and obtain the equivalent thermal resistance network of the core, winding and epoxy resin in the X, Y and Z directions.

[0078] The 3D geometric model of a high-frequency transformer based on epoxy resin casting, and the basic model of the thermal network model, can be divided into two types: cuboid elements and arc elements. Among them, the corner parts of the iron core ( S 2. S 6) is an arc-shaped unit, the yoke of the iron core ( S 1. S 3. S 4. S 5. S 7) The elements are cuboids, and the windings are also approximated as cuboids, as shown in the example below. Figure 3 The thermal resistance in three dimensions is calculated using the equivalent method of cuboid and arc-shaped elements, resulting in the equivalent thermal resistance network of the core, windings, and epoxy resin in the X, Y, and Z directions.

[0079] For a cuboid element, the thermal resistance in three directions can be calculated using the following equations:

[0080] ;

[0081] ;

[0082] ;

[0083] in, , and These represent the thermal resistances of the cuboid unit in three directions, respectively. , and Respectively, they are cuboid units , y and z Length in the direction. , and Respectively, the cuboid unit material in , y and z Thermal conductivity in the direction of direction.

[0084] Because the heat dissipation surface area is different in the two radial directions of the arc-shaped unit, its thermal resistance in the two radial directions is different. R O , R I They are also different. Therefore, R O , R I The following formulas should be used to calculate them respectively:

[0085] ;

[0086] ;

[0087] in, Indicates the angle of the arc-shaped unit. Represents arc-shaped unit Thermal conductivity in the direction, This represents the inner radius of the arc-shaped element. This represents the outer radius of the arc-shaped unit.

[0088] Thermal resistance in the circumferential direction R X , R Y Its heat flux length is equal to the average arc length of the arc-shaped unit, therefore R X , R Y It can be calculated using the following formula:

[0089] ;

[0090] in, Represents arc-shaped unit y Thermal conductivity in the direction of direction.

[0091] For axial thermal resistance R Z It is calculated using the following formula:

[0092] ;

[0093] in, Represents arc-shaped unit y Thermal conductivity in the direction of direction.

[0094] S4. Based on the simulation results of S1, construct the thermal resistance for heat conduction, heat transfer, and heat radiation.

[0095] Heat exchange in high-frequency transformers is mainly achieved through three mechanisms: heat conduction, convection, and radiation. Inside the high-frequency transformer, heat is transferred through heat conduction via the core, windings, and epoxy resin; on the surface of the high-frequency transformer, heat is dissipated to the surrounding air through convection and radiation.

[0096] The heat conduction between internal components of a high-frequency transformer can be calculated using the following thermal equation:

[0097] ;

[0098] in, It is the heat conducted between the internal components of the high-frequency transformer. It is the thermal conductivity of the material. A s It is the cross-sectional area perpendicular to the heat transfer direction, Δ T It is the temperature difference between objects. This indicates the path length in the heat transfer direction.

[0099] Thermal conduction and thermal resistance R t It can be represented by the following expression:

[0100] ;

[0101] in, It is the path length in the heat transfer direction.

[0102] On the surface of a high-frequency transformer, convective heat transfer occurs between the epoxy resin surface and the air. The heat transfer equation can be expressed as follows:

[0103] ;

[0104] in, It is the heat transferred by convection between the epoxy resin surface and the air. h c It is the convective heat transfer coefficient on the surface of the high-frequency transformer. T s It is the surface temperature of the high-frequency transformer. Indicates ambient temperature.

[0105] Convection heat transfer thermal resistance R c It can be represented by the following expression:

[0106] ;

[0107] The core of calculating convective heat transfer resistance lies in determining the convective heat transfer coefficient. h c This embodiment extracts the convective heat flux density of the epoxy resin surface in the temperature field of the finite element model. q c and the temperature difference Δ between the surface and the environment T Calculate the convective heat transfer coefficient on the surface of a high-frequency transformer. The calculation formula is as follows:

[0108] ;

[0109] During stable operation of epoxy resin cast high-frequency transformers, surface heat dissipation reaches a steady state, with the surface temperature exceeding 80℃. Due to the significant temperature difference between the surface and the environment, radiative heat transfer contributes significantly to the total heat dissipation. The radiative heat transfer between the epoxy resin surface of the high-frequency transformer and the ambient air can be described by the following thermal equation:

[0110] ;

[0111] in, It refers to the radiative heat transfer between the epoxy resin surface of the high-frequency transformer and the ambient air. h r It is the radiative heat transfer coefficient between the epoxy resin surface of the high-frequency transformer and the ambient air. T s It is the temperature of the epoxy resin surface of the high-frequency transformer.

[0112] Radiative heat transfer thermal resistance R r It can be represented by the following expression:

[0113] ;

[0114] Temperature of epoxy resin surface in temperature field extracted based on finite element analysis T s The radiative heat transfer coefficient of the surface of a high-frequency transformer can be calculated using the following formula:

[0115] ;

[0116] in, σ It is Boltzmann's constant. σ =5.67×10 -8 W / (m 2 ×K 4 ), ε It is the radiation coefficient. ε =0.8.

[0117] Figure 4 middle, h c_is and h c_os These are the convective heat transfer coefficients of the inner and outer surfaces, respectively. h r_is and h r_os These are the radiative heat transfer coefficients of the inner and outer surfaces, respectively.

[0118] S5. Based on the heat source, thermal conduction resistance, convective thermal resistance, radiative thermal resistance, heat capacity, and ambient node temperature, a complete 3D thermal network model of a high-frequency transformer is established.

[0119] The 3D thermal network (TN) model of an epoxy resin cast high-frequency transformer consists of the following five parts: heat source, thermal conduction resistance, thermal convection resistance, thermal radiation resistance, heat capacity, and ambient node temperature. T 0. These components together construct an equivalent thermal network for accurately predicting the steady-state temperature distribution of the transformer. Core and winding losses are injected into the corresponding nodes of the 3DTN model through heat flow source modules in Simulink, with the heat flow source values ​​taken from the loss values ​​of each region in Table 2 of step two. There are a total of 8 nodes in the primary and secondary windings, and the total winding loss is evenly distributed based on the volume ratio of each node to reflect the spatial distribution characteristics of the winding loss.

[0120] The core thermal network model is divided into two types of geometric elements: cuboid elements at the yoke and arc-shaped elements at the corners, to accurately capture the spatial characteristics of loss distribution. The thermal resistance of the cuboid elements and the arc-shaped elements are calculated using the formula in step three.

[0121] Since the axial (Y-direction) cross-sectional area of ​​the winding is small, its contribution to the overall temperature distribution through axial heat conduction is limited. In this embodiment, axial heat transfer of the winding is ignored, and the winding is approximated as a cuboid element to simplify the construction of the thermal network model. The thermal resistance of the cuboid element of the winding is calculated using the formula in step three, fully considering the radial heat flow characteristics.

[0122] The epoxy resin, with a near-cubic-pitch structure, completely encapsulates the high-frequency transformer, forming an external encapsulation layer for heat transfer. The high-frequency transformer's epoxy resin thermal network module consists of three parts: thermal conductivity resistance, convective thermal conductivity resistance, and radiative thermal conductivity resistance, used to accurately describe the transformer's heat transfer characteristics. The thermal conductivity resistance is calculated based on the geometric characteristics of the cuboid element using the formula in step three. The convective thermal conductivity resistance and radiative thermal conductivity resistance are calculated using the formulas in step four, comprehensively considering the convection and radiation heat dissipation mechanisms between the surface and the environment.

[0123] Based on the establishment of 3D thermal network models of various components of a high-frequency transformer cast in epoxy resin, a complete 3D thermal network model of the high-frequency transformer can be established. Figure 5middle, P n ( n =1-12) represents the node loss. R icn_X ( n =1-7), R icn_Y ( n =1-7), R icn_Z ( n =1-7) represent the thermal resistance of the iron core in the X, Y, and Z directions, respectively. R icn_O ( n =2,6) and R icn_I ( n =2,6) represent the thermal resistance of the arc-shaped iron core element in the outer and inner diameter directions, respectively. R con_X ( n =8-11) is the thermal resistance of the winding in the X direction. R con_Z ( n =12-15) is the thermal resistance of the winding in the Z direction. R ern_X ( n =3,4,5,9,11) R ern_Y ( n =1,7) R ern_Z ( n =1-7,13,15) represent the thermal resistance of epoxy resin in the X, Y, and Z directions, respectively. R chn_X ( n =3,5,9,11) R chn_Y ( n =1,7) R chn_Z ( n =1-3,5-7,13,15) represent the convective heat transfer resistances of the epoxy resin surface in the X, Y, and Z directions, respectively. R rhn_X ( n =3,5,9,11) R rhn_Y ( n =1,7) R rhn_Z ( n =1-3,5-7,13,15) represent the radiative thermal resistance of the epoxy resin surface in the X, Y, and Z directions, respectively. T 0 represents ambient temperature, Cth_ir C th_co These are the heat capacities of the core and windings, respectively.

[0124] The temperature rise prediction results of the nodes in the 3D thermal network model of the high-frequency transformer are shown in Table 3:

[0125] Table 3 Prediction results of high-frequency transformer node temperature rise

[0126] ;

[0127] This invention constructs a finite element model of a high-frequency transformer, couples the magnetic and temperature fields, and extracts the loss distribution and surface temperature. The core and windings are divided into 15 heat source nodes, and the three-dimensional thermal resistance is calculated based on the equivalent method of cuboid and arc-shaped elements. Combining the finite element analysis results, the surface convective and radiative heat transfer coefficients are calculated to construct the convective and radiative thermal resistances. A 3D thermal network model is built on the Simulink platform, outputting the steady-state temperature rise of each node with an error of less than 5%, meeting engineering accuracy requirements. This invention significantly improves the accuracy of temperature rise prediction and computational efficiency by comprehensively considering the mechanisms of heat conduction, convection, and radiation, and is suitable for thermal analysis of high-frequency transformers under complex operating conditions.

[0128] Therefore, the present invention adopts the above-mentioned three-dimensional thermal network modeling method for high-frequency transformers that considers the heat transfer mechanism. By establishing a 3D thermal network model of the high-frequency transformer, the temperature distribution of the high-frequency transformer in three-dimensional space can be accurately reflected. This three-dimensional thermal network model can accurately predict the temperature rise changes inside the transformer, especially under complex working conditions, providing a more intuitive and accurate temperature prediction, thereby effectively avoiding the blind spots of traditional two-dimensional models that cannot make comprehensive predictions.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for modeling a three-dimensional thermal network of a high-frequency transformer considering heat transfer mechanisms, characterized in that, Includes the following steps: S1. Construct a finite element model of a high-frequency transformer and perform magnetothermal coupling simulation; S2. Divide the core and windings of the high-frequency transformer into nodal regions; S3. Calculate the thermal resistance of the 3D geometric model of the high-frequency transformer for different node regions; S4. Based on the simulation results of S1, construct the thermal resistance for heat conduction, heat transfer, and heat radiation. S5. Based on the heat source, thermal conduction resistance, convective thermal conduction resistance, radiative thermal resistance, heat capacity, and ambient node temperature, establish a complete 3D thermal network model of the high-frequency transformer. In step S4, the heat conduction between the internal components of the high-frequency transformer is calculated using the following thermal equation: ； in, It is the heat conducted between the internal components of the high-frequency transformer. It is the thermal conductivity of the material. It is the cross-sectional area perpendicular to the heat transfer direction. It is the temperature difference between objects. Indicates the path length in the direction of heat transfer; Thermal conduction and thermal resistance It can be represented by the following expression: ； in, It is the path length in the direction of heat transfer; In step S4, the convective heat transfer between the epoxy resin surface and the air on the surface of the high-frequency transformer is represented by the following equation: ； in, It is the heat transferred by convection between the epoxy resin surface and the air. It is the convective heat transfer coefficient on the surface of the high-frequency transformer. It is the surface temperature of the high-frequency transformer. Indicates ambient temperature; Convection heat transfer thermal resistance It is represented by the following expression: ； The convective heat flux density of the epoxy resin surface and the temperature difference between the surface and the environment in the temperature field of the finite element model are extracted to calculate the convective heat transfer coefficient of the high-frequency transformer surface. ； in, This represents the convective heat flux density on the surface of the epoxy resin. This indicates the temperature difference between the epoxy resin surface and the environment; In step S4, the radiative heat transfer between the epoxy resin surface of the high-frequency transformer and the ambient air is calculated using the following thermal equation: ； in, It refers to the radiative heat transfer between the epoxy resin surface of the high-frequency transformer and the ambient air. It is the radiative heat transfer coefficient between the epoxy resin surface of the high-frequency transformer and the ambient air. It is the temperature of the epoxy resin surface of the high-frequency transformer; Radiative heat transfer thermal resistance It is represented by the following expression: ； Temperature of epoxy resin surface in temperature field extracted based on finite element analysis T s Calculate the radiative heat transfer coefficient of the surface of the high-frequency transformer: ； in, It is Boltzmann's constant. =5.67×10 -8 W / (m 2 ×K 4 ), It is the radiation coefficient. =0.

8.

2. The method for modeling a three-dimensional thermal network of a high-frequency transformer considering heat transfer mechanisms according to claim 1, characterized in that, Step S1 specifically involves: establishing a finite element model of the high-frequency transformer based on its topology and electrical design parameters, and performing a two-way magnetic-thermal coupling physical field simulation to extract the loss distribution and surface temperature of the high-frequency transformer; solving the loss and temperature fields through two-way iterative calculation using magnetic-thermal coupling, considering the nonlinear hysteresis characteristics of the core and the skin and proximity effect losses of the conductors to ensure the physical accuracy of the initial loss distribution, and extracting the loss distribution and surface temperature to provide data for thermal network modeling.

3. The method for modeling a three-dimensional thermal network of a high-frequency transformer considering heat transfer mechanisms according to claim 1, characterized in that, Step S2 specifically involves: based on the spatial location and loss distribution of the core and windings, the core is divided into 7 regions along the geometric structure, and the primary and secondary windings are divided into 8 regions along the four radial directions, thus constructing a total of 15 heat source nodes; the heating power of each heat source node is taken from the copper loss or iron loss of the corresponding region in the simulation results of step S1, and converted into a quantitative heat flow source input to the heat network; based on simulation analysis, the loss values ​​of each region of the core and windings are extracted.

4. The method for modeling a three-dimensional thermal network of a high-frequency transformer considering heat transfer mechanisms according to claim 1, characterized in that, Step S3 specifically involves: for regions with different geometric shapes, using the equivalent method of cuboid units and arc units, calculating the thermal resistance in three dimensions, and obtaining the equivalent thermal resistance network of the core, windings, and epoxy resin in the X, Y, and Z directions; the corner part of the core is an arc unit, the yoke of the core is a cuboid unit, and the windings are considered to be cuboid units.

5. A method for modeling a three-dimensional thermal network of a high-frequency transformer considering heat transfer mechanisms according to claim 4, characterized in that: In step S3, for the cuboid element, the thermal resistance in the three directions is calculated by the following equations: ； ； ； in, , and These represent the thermal resistances of the cuboid unit in three directions, respectively. , and Respectively, they are cuboid units , and Length in the direction, , and Respectively, the cuboid unit material in , and Thermal conductivity in the direction of direction.

6. A method for modeling a three-dimensional thermal network of a high-frequency transformer considering heat transfer mechanisms according to claim 5, characterized in that: In step S3, for the arc-shaped element, the thermal resistance in both radial directions is expressed as: ； ； in, and Thermal resistance in the radial directions of the arc-shaped unit. Indicates the angle of the arc-shaped unit. Represents arc-shaped unit Thermal conductivity in the direction, This represents the inner radius of the arc-shaped element. Indicates the outer radius of the arc-shaped unit; For arc-shaped elements, the thermal resistance in the circumferential direction Represented as: ； in, Represents arc-shaped unit Thermal conductivity in the direction of direction; For arc-shaped units, the axial thermal resistance Represented as: ； in, Represents arc-shaped unit Thermal conductivity in the direction of direction.

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