A Design Method and Device of Magnetic-Integrated Transformer for CLLC Converter

Abstract

The present invention discloses a design method and device for a magnetically integrated transformer for a CLLC converter, which relates to the technical field of high-frequency transformer design and is used to solve the technical problem of poor design accuracy of the existing design method for a magnetically integrated transformer for a CLLC converter. The method includes determining the total number of turns of the primary and secondary winding coils, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, and the lengths of the left and right side magnetic powder core columns based on a preset transformer magnetic circuit model, a preset area product method, and preset constraint conditions, further obtaining the magnetic resistance of the magnetic flux branch, considering the air-gap edge magnetic flux effect to determine the precise air-gap length, and fully considering the magnetic resistance at the core corners and the additional leakage inductance in the air near the winding coils to determine the primary leakage inductance in the target core magnetic circuit, the total amount of additional primary leakage inductance of the target air, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns, and then combining the preset coil winding method to design a magnetically integrated transformer for a CLLC converter.

Description

Technical Field

[0001] The present invention relates to the technical field of high - frequency transformer design, and particularly to a design method and device for a magnetically integrated transformer for a CLLC converter. Background Art

[0002] With the rapid development of the power supply industry, the power supply is continuously optimized towards high frequency, high efficiency, and high power density. The CLLC converter stands out among many topologies due to its advantages such as bidirectional current flow, high conversion efficiency, and high switching frequency. However, the CLLC converter has multiple magnetic components, resulting in a large power supply volume and low power density. If multiple magnetic components can be integrated together through a magnetic integration method, the volume of the power supply can be significantly reduced and the power density can be increased. Therefore, the magnetic integration technology of the CLLC converter has received extensive attention and research in the academic and industrial fields.

[0003] Currently, the magnetic integration schemes of the CLLC converter are mainly divided into two categories: decoupled integration and leakage inductance integration. The conventional method of decoupled integration is to wind the resonant inductor and the transformer on different magnetic posts respectively, so that the magnetic flux flows of the two do not interfere with each other, thereby achieving decoupling, and then design the magnetic core together. However, the reduction of the volume of the magnetic components by decoupled integration is very limited, only reducing the volume at the connection part of the magnetic core of the two. The leakage inductance integration is to make the transformer generate a certain value of large leakage inductance and use the large leakage inductance to replace the resonant inductor. The advantage of this scheme is that the volume occupied by the resonant inductor can be removed, and a higher power density can be obtained.

[0004] Most of the existing design methods for magnetically integrated transformers for CLLC converters can control the magnitude of the leakage inductance by adjusting the air - gap size between the middle post and the side posts of the magnetic core, and the number distribution of the primary and secondary windings on the two side posts of the magnetic core, thereby completing the design of the transformer. However, this method uses a relatively small - width air - gap in the side - post magnetic - flux branch to achieve a large magnetic resistance, resulting in a large magnetic potential difference at both ends of the air - gap, and the leakage magnetic flux in the air will also increase, making it impossible to accurately control the leakage inductance of the magnetically integrated transformer, leading to poor design accuracy of the magnetically integrated transformer for the CLLC converter. Summary of the Invention

[0005] The present invention provides a design method and device for a magnetically integrated transformer for a CLLC converter, which are used to solve the technical problem that the existing design method for a magnetically integrated transformer for a CLLC converter cannot accurately control the leakage inductance of the magnetically integrated transformer, resulting in poor design accuracy of the magnetically integrated transformer for the CLLC converter.

[0006] A design method for a magnetically integrated transformer for a CLLC converter provided in the first aspect of the present invention includes:

[0007] Obtain the transformer design parameters, and use the preset area product method to determine the total number of turns of the primary and secondary winding coils, the core model, and the geometric parameters of the core structure corresponding to the core model according to the transformer design parameters;

[0008] Use the preset constraint conditions to determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters;

[0009] Use the preset transformer magnetic circuit model to calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters;

[0010] Determine the precise middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the core structure;

[0011] Use the preset core corner model to calculate the magnetic resistance at the core corners of the left and right side columns according to the geometric parameters of the core structure and the magnetic flux of the magnetic flux branch;

[0012] Based on the geometric parameters of the core structure, the lengths of the left and right side magnetic powder core columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch, determine the magnetic resistance of the left and right side magnetic powder core columns and the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns;

[0013] According to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right side magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right side magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns, and the preset design leakage inductance, determine the primary leakage inductance in the target core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns;

[0014] Based on the preset coil winding method, design a magnetic integrated transformer for a CLLC converter through the sum of the primary leakage inductance in the target core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right side magnetic powder core columns, the precise middle column air gap length, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns.

[0015] Optionally, the preset constraint conditions are specifically:

[0016] The product of the number of turns of the primary winding coil allocated to the left side column and the number of turns of the secondary winding coil is equal to the product of the number of turns of the primary winding coil allocated to the right side column and the number of turns of the secondary winding coil.

[0017] Optionally, the number of turns of the primary and secondary winding coils allocated to the left and right side columns includes the number of turns of the primary winding coil of the left side column, the number of turns of the secondary winding coil of the left side column, the number of turns of the primary winding coil of the right side column, and the number of turns of the secondary winding coil of the right side column; the lengths of the left and right magnetic powder core columns include the length of the left magnetic powder core column and the length of the right magnetic powder core column; the method of using preset constraint conditions to determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right magnetic powder core columns, and the electrical isolation distance between the left and right inner and outer layer coils according to the transformer design parameters includes:

[0018] Using preset constraint conditions, calculate the number of turns of the primary winding coil of the left side column, the number of turns of the secondary winding coil of the left side column, the number of turns of the primary winding coil of the right side column, and the number of turns of the secondary winding coil of the right side column according to the primary resonance inductance value and the secondary resonance inductance value in the transformer design parameters;

[0019] Based on the number of turns of the primary winding coil of the left side column and the number of turns of the secondary winding coil of the left side column, determine the width of the primary winding coil of the left side column and the width of the secondary winding coil of the left side column in the case of tight winding;

[0020] Compare the width of the primary winding coil of the left side column and the width of the secondary winding coil of the left side column in the case of tight winding;

[0021] Take the maximum of the width of the primary winding coil of the left side column or the width of the secondary winding coil of the left side column as the target width of the winding coil of the left side column, and determine the length of the left magnetic powder core column based on the target width of the winding coil of the left side column;

[0022] Based on the number of turns of the primary winding coil of the right side column and the number of turns of the secondary winding coil of the right side column, determine the width of the primary winding coil of the right side column and the width of the secondary winding coil of the right side column in the case of tight winding;

[0023] Compare the width of the primary winding coil of the right side column and the width of the secondary winding coil of the right side column in the case of tight winding;

[0024] Take the maximum of the width of the primary winding coil of the right side column or the width of the secondary winding coil of the right side column as the target width of the winding coil of the right side column, and determine the length of the right magnetic powder core column based on the target width of the winding coil of the right side column;

[0025] Calculate the electrical isolation distance between the inner and outer coils on the left and right sides according to the transformer input voltage and transformer output voltage in the transformer design parameters.

[0026] Optionally, calculating the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch by using the preset transformer magnetic circuit model according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters, includes:

[0027] Calculate the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the primary resonance inductance value, the secondary resonance inductance value, the primary excitation inductance value of the transformer, and the total number of turns of the primary and secondary winding coils in the transformer design parameters;

[0028] Divide the preset transformer magnetic circuit model to generate the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch;

[0029] Use the magnetic flux branch method to model according to the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch to generate a relationship equation set between the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch;

[0030] Use the relationship equation set between the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch to calculate the magnetic flux of the magnetic flux branch according to the total magnetic resistance of the side column magnetic flux branch, the total magnetic resistance of the middle column magnetic flux branch, the total number of turns of the primary and secondary winding coils, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the current of the primary winding coil and the current of the secondary winding coil in the transformer design parameters;

[0031] ;

[0032] Among them, A is the total magnetic resistance parameter of the first side column; B is the total magnetic resistance parameter of the second side column; C is the total magnetic resistance parameter of the third side column; D is the total magnetic resistance parameter of the first middle column; E is the total magnetic resistance parameter of the second middle column; F is the total magnetic resistance parameter of the third middle column; G is the total magnetic resistance parameter of the fourth middle column; H is the total magnetic resistance parameter of the fifth middle column; is the total magnetic resistance of the side column magnetic flux branch; is the total magnetic resistance of the middle column magnetic flux branch; is the inductance value of the primary resonance inductance; is the inductance value of the secondary resonance inductance; is the number of turns of the primary winding coil allocated to the left side column; is the number of turns of the secondary winding coil allocated to the left side column; is the total number of turns of the secondary winding coil; is the total number of turns of the primary winding coil; is the number of turns of the primary winding coil allocated to the right side leg; is the number of turns of the secondary winding coil allocated to the right side leg; is the primary excitation inductance value of the transformer.

[0033] Optionally, the magnetic flux of the magnetic flux branch includes the magnetic flux of the left side leg magnetic flux branch and the magnetic flux of the right side leg magnetic flux branch; the preset magnetic core corner model includes the left side leg magnetic core corner model and the right side leg magnetic core corner model; the magnetic resistance at the magnetic core corners of the left and right side legs includes the magnetic resistance at the magnetic core corner of the left side leg and the magnetic resistance at the magnetic core corner of the right side leg; the step of calculating the magnetic resistance at the magnetic core corners of the left and right side legs by using the preset magnetic core corner model according to the geometric parameters of the magnetic core structure and the magnetic flux of the magnetic flux branch includes:

[0034] Dividing the left side leg magnetic core corner model and the right side leg magnetic core corner model respectively by using the width of the magnetic core side leg in the geometric parameters of the magnetic core structure to determine the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side leg magnetic core corner model and the right side leg magnetic core corner model;

[0035] Performing magnetic resistance operations on the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side leg magnetic core corner model by using the magnetic flux of the left side leg magnetic flux branch, the width of the magnetic core side leg and the thickness of the magnetic core in the geometric parameters of the magnetic core structure to determine the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the left side leg magnetic core corner model;

[0036] Connecting in parallel the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the left side leg magnetic core corner model to determine the magnetic resistance at the magnetic core corner of the left side leg;

[0037] Performing magnetic resistance operations on the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the right side leg magnetic core corner model by using the magnetic flux of the right side leg magnetic flux branch, the width of the magnetic core side leg and the thickness of the magnetic core in the geometric parameters of the magnetic core structure to determine the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the right side leg magnetic core corner model;

[0038] Parallelize the reluctances of the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region, and the magnetic core window inner corner region corresponding to the right side post magnetic core corner model to determine the reluctance at the right side post magnetic core corner.

[0039] Optionally, the reluctances of the left and right magnetic powder core posts include the reluctance of the left magnetic powder core post and the reluctance of the right magnetic powder core post; the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core posts includes the magnetic permeability of the magnetic powder core material of the left magnetic powder core post and the magnetic permeability of the magnetic powder core material of the right magnetic powder core post; determining the reluctances of the left and right magnetic powder core posts and the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core posts based on the geometric parameters of the magnetic core structure, the lengths of the left and right magnetic powder core posts, the magnetic fluxes of the magnetic flux branches, and the total reluctance of the side post magnetic flux branches includes:

[0040] Use the length of the left magnetic powder core post, the length of the right magnetic powder core post, the magnetic fluxes of the magnetic flux branches, and the width of the magnetic core window, the height of the magnetic core window, the width of the magnetic core side post, and the thickness of the magnetic core in the geometric parameters of the magnetic core structure to calculate the reluctances of the left remaining magnetic core magnetic path and the right remaining magnetic core magnetic path;

[0041] Calculate the reluctance of the left magnetic powder core post according to the reluctance of the left remaining magnetic core magnetic path and the total reluctance of the side post magnetic flux branches;

[0042] Calculate the reluctance of the right magnetic powder core post according to the reluctance of the right remaining magnetic core magnetic path and the total reluctance of the side post magnetic flux branches;

[0043] Based on the reluctance of the left magnetic powder core post, the length of the left magnetic powder core post, the width of the magnetic core side post and the thickness of the magnetic core in the geometric parameters of the magnetic core structure, calculate the magnetic permeability of the magnetic powder core material of the left magnetic powder core post;

[0044] Based on the reluctance of the right magnetic powder core post, the length of the right magnetic powder core post, the width of the magnetic core side post and the thickness of the magnetic core in the geometric parameters of the magnetic core structure, calculate the magnetic permeability of the magnetic powder core material of the right magnetic powder core post.

[0045] Optionally, determining the primary leakage inductance in the target magnetic core magnetic path, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core posts according to the total reluctance of the side post magnetic flux branches, the geometric parameters of the magnetic core structure, the total reluctance of the middle post magnetic flux branches, the magnetic fluxes of the magnetic flux branches, the reluctances of the left and right magnetic powder core posts, the number of turns of the primary and secondary winding coils allocated to the left and right side posts, the transformer design parameters, the lengths of the left and right magnetic powder core posts, the electrical isolation distance between the inner and outer layers of the left and right coils, the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core posts, and the preset design leakage inductance includes:

[0046] Using the magnetic resistance of the left and right magnetic powder core columns, the magnetic flux of the magnetic flux branch, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the length of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the geometric parameters of the magnetic core structure, and the transformer design parameters, calculate the additional leakage inductance in the air near the initial winding coil;

[0047] Based on the preset designed leakage inductance, determine the primary leakage inductance in the initial magnetic core magnetic circuit;

[0048] Fine-tune the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns to determine the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns;

[0049] Using the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns, the length of the left and right magnetic powder core columns, the width of the magnetic core side column in the transformer design parameters, and the thickness of the magnetic core, update the magnetic resistance of the left and right magnetic powder core columns to determine the magnetic resistance of the middle left and right magnetic powder core columns;

[0050] Using the total magnetic resistance of the side column magnetic flux branch, the magnetic resistance of the middle left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, and the total magnetic resistance of the middle column magnetic flux branch, update the primary leakage inductance in the initial magnetic core magnetic circuit to determine the primary leakage inductance in the middle magnetic core magnetic circuit;

[0051] Based on the magnetic resistance of the middle left and right magnetic powder core columns, update the additional leakage inductance in the air near the initial winding coil to determine the additional leakage inductance in the air near the middle winding coil;

[0052] Judge whether the sum of the additional leakage inductance in the air near the middle winding coil and the primary leakage inductance in the middle magnetic core magnetic circuit is equal to the preset designed leakage inductance;

[0053] If so, use the additional leakage inductance in the air near the middle winding coil as the additional leakage inductance in the air near the target winding coil, use the primary leakage inductance in the middle magnetic core magnetic circuit as the primary leakage inductance in the target magnetic core magnetic circuit, and use the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns as the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core columns.

[0054] Optionally, the step of using the magnetic resistance of the left and right magnetic powder core columns, the magnetic flux of the magnetic flux branch, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the length of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the geometric parameters of the magnetic core structure, and the transformer design parameters to calculate the additional leakage inductance in the air near the initial winding coil includes:

[0055] Calculate the magnetic voltage drop across the left and right magnetic powder core magnetic columns using the magnetic resistance of the left and right magnetic powder core magnetic columns and the magnetic flux of the magnetic flux branch.

[0056] Calculate the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, and the magnetic field strength in the secondary winding coil of the left and right side columns according to the magnetic voltage drop across the left and right magnetic powder core magnetic columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the length of the left and right magnetic powder core magnetic columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, and the transformer design parameters.

[0057] Calculate the total air leakage inductance energy of the winding coils of the left and right side columns using the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, the magnetic field strength in the secondary winding coil of the left and right side columns, and the geometric parameters of the magnetic core structure.

[0058] Determine the primary leakage inductance on the left side column and the primary leakage inductance on the right side column based on the total air leakage inductance energy of the winding coils of the left and right side columns and the transformer design parameters.

[0059] Add the primary leakage inductance on the left side column and the primary leakage inductance on the right side column to determine the additional leakage inductance in the air near the initial winding coil.

[0060] Optionally, the precise middle column air gap length is specifically:

[0061] ;

[0062] Wherein, is the precise middle column air gap length; is the total magnetic resistance of the magnetic flux branch of the middle column; a is the first precise middle column air gap length parameter; b is the second precise middle column air gap length parameter; c is the third precise middle column air gap length parameter; d is the fourth precise middle column air gap length parameter; is the height of the magnetic core window; is the width of the middle column of the magnetic core; is the thickness of the magnetic core; is the magnetic permeability of the magnetic core material of the EE-type magnetic core used; is the magnetic permeability of air.

[0063] A magnetic integration transformer design device provided in the second aspect of the present invention includes:

[0064] An acquisition module, configured to acquire transformer design parameters, and determine the total number of turns of the primary and secondary winding coils, the core model, and the geometric parameters of the core structure corresponding to the core model according to the transformer design parameters by using a preset area product method;

[0065] A first calculation module, configured to determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters by using preset constraint conditions;

[0066] A second calculation module, configured to calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters by using a preset transformer magnetic circuit model;

[0067] A third calculation module, configured to determine the accurate middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the core structure;

[0068] A fourth calculation module, configured to calculate the magnetic resistance at the magnetic core corners of the left and right side columns according to the geometric parameters of the core structure and the magnetic flux of the magnetic flux branch by using a preset magnetic core corner model;

[0069] A fifth calculation module, configured to determine the magnetic resistance of the left and right side magnetic powder core columns and the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns based on the geometric parameters of the core structure, the lengths of the left and right side magnetic powder core columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch;

[0070] An output target parameter module, configured to determine the primary side leakage inductance in the target magnetic core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns according to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right side magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right side magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns, and a preset design leakage inductance;

[0071] A design module, configured to design a magnetic integrated transformer for a CLLC converter based on a preset coil winding method, the sum of the primary side leakage inductance in the target magnetic core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right side magnetic powder core columns, the accurate middle column air gap length, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns.

[0072] As can be seen from the above technical solutions, the present invention has the following advantages:

[0073] The above technical solution of the present invention provides a design method for a magnetically integrated transformer for a CLLC converter. First, obtain the transformer design parameters, and use the preset area product method to determine the total number of turns of the primary and secondary winding coils, the core model, and the geometric parameters of the core structure corresponding to the core model according to the transformer design parameters; then, use the preset constraint conditions to determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters; use the preset transformer magnetic circuit model to calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters; determine the precise middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the core structure; use the preset core corner model to calculate the magnetic resistance at the core corners of the left and right side columns according to the geometric parameters of the core structure and the magnetic flux of the magnetic flux branch; based on the geometric parameters of the core structure, the lengths of the left and right side magnetic powder core columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch, determine the magnetic resistance of the left and right side magnetic powder core columns and the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns; according to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right side magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right side magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns, and the preset design leakage inductance, determine the primary side leakage inductance in the target core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns; finally, based on the preset coil winding method, design a magnetically integrated transformer for a CLLC converter through the sum of the primary side leakage inductance in the target core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right side magnetic powder core columns, the precise middle column air gap length, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns; based on the above solution, the present invention combines the preset coil winding method and the equal-length left and right side magnetic powder core column lengths, making the leakage magnetic flux distribution in the air near the winding coil more regular. At the same time, it also takes into account the core corners, the precise middle column air gap length, and the additional air leakage inductance, thereby realizing precise control of the transformer leakage inductance, and further improving the design accuracy of the magnetically integrated transformer for a CLLC converter. Description of the Drawings

[0074] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0075] Figure 1 It is a flowchart of the steps of a design method for a magnetic integrated transformer for a CLLC converter provided in Embodiment 1 of the present invention;

[0076] Figure 2 It is a schematic structural diagram of a magnetic integrated transformer for a CLLC converter provided in Embodiment 1 of the present invention;

[0077] Figure 3 It is a geometric structure diagram of an EE-shaped magnetic core provided in Embodiment 1 of the present invention;

[0078] Figure 4 It is a schematic structural diagram of a simplified magnetic circuit model of a transformer provided in Embodiment 1 of the present invention;

[0079] Figure 5 It is a schematic structural diagram of a circuit model of a transformer provided in Embodiment 1 of the present invention;

[0080] Figure 6 It is a schematic structural diagram of a middle column model with an air gap opened provided in Embodiment 1 of the present invention;

[0081] Figure 7 It is a schematic structural diagram of a magnetic core corner model provided in Embodiment 1 of the present invention;

[0082] Figure 8 It is a simplified structural diagram of the left side column and the winding coil provided in Embodiment 1 of the present invention;

[0083] Figure 9 It is a schematic flow diagram of a design method for a magnetic integrated transformer for a CLLC converter provided in Embodiment 2 of the present invention;

[0084] Figure 10 It is a structural block diagram of a design device for a magnetic integrated transformer for a CLLC converter provided in Embodiment 3 of the present invention;

[0085] Among them, the meanings of the reference signs of the accompanying drawings are as follows:

[0086] 1. EE core; 2. Central column air gap; 3. Left magnetic powder core magnetic column; 4. Right magnetic powder core magnetic column; 5. Left side column secondary winding coil; 6. Right side column secondary winding coil; 7. Left side column primary winding coil; 8. Right side column primary winding coil; 9. Side column core; 10. Magnetic powder core magnetic column; 11. Primary winding; 12. Secondary winding. Detailed implementation manners

[0087] An embodiment of the present invention provides a design method and device for a magnetic integrated transformer for a CLLC converter, which are used to solve the technical problem that the existing design method for a magnetic integrated transformer for a CLLC converter cannot accurately control the leakage inductance of the magnetic integrated transformer, resulting in poor design accuracy of the magnetic integrated transformer for a CLLC converter.

[0088] In order to make the invention objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0089] Term explanation: A CLLC converter (Capacitor - Inductor - Inductor - Capacitor Converter) is a power conversion device that can convert direct current flowing in both directions into direct current.

[0090] Please refer to Figure 1 , Figure 1 which is a step flow chart of a design method for a magnetic integrated transformer for a CLLC converter provided in Embodiment 1 of the present invention.

[0091] A design method for a magnetic integrated transformer for a CLLC converter provided by the present invention includes:

[0092] Step 101: Obtain transformer design parameters, and use the preset area product method to determine the total number of turns of the primary and secondary winding coils, the core model, and the core structure geometric parameters corresponding to the core model according to the transformer design parameters.

[0093] The preset area product method is the traditional AP method (Area Product Method).

[0094] The core model is the specific model of the selected EE core.

[0095] It should be noted that, please refer to Figure 2 , the structure of the magnetic integrated transformer proposed by the present invention is asFigure 2 As shown, the transformer core adopts an EE-type core structure. The primary winding coil and the secondary winding coil are wound on the left side post and the right side post of the core. Magnetic powder core columns of the same length as the winding coils are respectively placed on the left side post and the right side post, and an air gap is provided in the middle post of the core.

[0096] Furthermore, the obtained transformer design parameters are used as the initial input quantities of the present invention. The transformer design parameters include the turns ratio of the primary and secondary winding coils , the current of the primary winding coil , the current of the secondary winding coil , the primary resonant inductance value , the secondary resonant inductance value , the primary excitation inductance value of the transformer , the input voltage of the transformer , the output voltage of the transformer , the switching frequency .

[0097] Furthermore, please refer to Figure 3 . After obtaining the relevant design parameters, according to the traditional AP method, calculate and select the specific model of the EE-type core, and obtain the relevant structural geometric parameters of the EE-type core as Figure 3 shown. The structural geometric parameters of the core include: the width of the core side post , the width of the core window , the width of the core middle post , the height of the core upper and lower yokes , the height of the core window and the thickness of the core . The side post width and the upper and lower yoke height are equal.

[0098] Set the maximum working magnetic flux density of the core as , the total number of turns of the primary and secondary winding coils can be calculated. The total number of turns of the primary and secondary winding coils includes the total number of turns of the primary winding coil and the total number of turns of the secondary winding coil ; this process can be expressed as:

[0099] ;

[0100] ;

[0101] It is worth mentioning that according to the set current density of the coil winding, the wire diameter of the primary winding coil and the wire diameter of the secondary winding coil can be obtained.

[0102] Step 102: According to the transformer design parameters and using the preset constraint conditions, determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right magnetic powder core columns, and the electrical isolation distances between the inner and outer layer coils on the left and right sides.

[0103] The number of turns of the primary and secondary winding coils allocated to the left and right side columns includes the number of turns of the primary winding coil of the left side column, the number of turns of the secondary winding coil of the left side column, the number of turns of the primary winding coil of the right side column, and the number of turns of the secondary winding coil of the right side column.

[0104] The lengths of the left and right magnetic powder core columns include the length of the left magnetic powder core column and the length of the right magnetic powder core column.

[0105] The electrical isolation distances between the inner and outer layer coils on the left and right sides include the electrical isolation distance between the inner and outer layer coils on the left side column and the electrical isolation distance between the inner and outer layer coils on the right side column.

[0106] The preset constraint condition is that the product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the left side column is equal to the product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the right side column.

[0107] Specifically, Step 102 may include the following sub-steps S21 - S28:

[0108] Step S21: According to the preset constraint conditions and the values of the primary resonant inductance and the secondary resonant inductance in the transformer design parameters, calculate the number of turns of the primary winding coil of the left side column, the number of turns of the secondary winding coil of the left side column, the number of turns of the primary winding coil of the right side column, and the number of turns of the secondary winding coil of the right side column;

[0109] It should be noted that for a symmetric CLLC converter, the ratio of the value of the primary resonant inductance to the value of the secondary resonant inductance is equal to the square of the turns ratio n of the primary and secondary sides. According to this relationship, it can be deduced that the preset constraint condition is that the product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the left side column is equal to the product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the right side column, so as to calculate the number of turns of the primary winding and the number of turns of the secondary winding allocated to the left side column, the number of turns of the primary winding and the number of turns of the secondary winding allocated to the right side column, and and and are all integers and satisfy and The difference is the smallest, and this turn number distribution method is the optimal turn number distribution method.

[0110] Step S22: Based on the number of turns of the primary winding coil of the left side post and the number of turns of the secondary winding coil of the left side post, determine the width of the primary winding coil of the left side post and the width of the secondary winding coil of the left side post under the condition of tight winding;

[0111] Step S23: Compare the width of the primary winding coil of the left side post and the width of the secondary winding coil of the left side post under the condition of tight winding;

[0112] Step S24: Take the maximum width of the primary winding coil of the left side post or the width of the secondary winding coil of the left side post as the target width of the left side post winding coil, and based on the target width of the left side post winding coil, determine the length of the left magnetic powder core magnetic post;

[0113] It should be noted that calculate the width of the coil of the primary winding on the left side post under the condition of tight winding , calculate the width of the coil of the secondary winding on the left side post under the condition of tight winding , take the maximum value of the two as the designed coil width of the left side post (i.e., the target width of the left side post winding coil ), that is . Compare the coil with the larger coil width between the primary winding coil and the secondary winding coil on the left side post under tight winding. The coil with the larger coil width is wound on the inner layer, and the winding method is tight winding. The winding coil width is , and the coil with the smaller coil width is wound on the outer layer, and the winding method is uniform winding. The winding coil width is also equal to , so that the primary winding coil and the secondary winding coil on the left side post are of equal length. Let the length of the left magnetic powder core magnetic post be equal to the designed coil width of the left side post .

[0114] Step S25: Based on the number of turns of the primary winding coil of the right side post and the number of turns of the secondary winding coil of the right side post, determine the width of the primary winding coil of the right side post and the width of the secondary winding coil of the right side post under the condition of tight winding;

[0115] Step S26: Compare the width of the primary winding coil of the right side post and the width of the secondary winding coil of the right side post under the condition of tight winding;

[0116] Step S27: Take the maximum width of the primary winding coil of the right side post or the width of the secondary winding coil of the right side post as the target width of the right side post winding coil, and based on the target width of the right side post winding coil, determine the length of the right magnetic powder core magnetic post;

[0117] It should be noted that based on the above steps and principles for calculating the coil width of the primary side winding on the left side column under the condition of tight winding, calculate the coil width of the primary side winding on the right side column under the condition of tight winding. Calculate the coil width of the secondary side winding on the right side column under the condition of tight winding. Take the maximum value of the two as the designed coil width of the right side column (i.e., the target coil width of the right side column winding). That is . Compare the coil widths of the primary side winding coil and the secondary side winding coil on the right side column. The coil with the larger coil width under tight winding is wound on the inner layer, and the winding method is tight winding. The winding coil width is . The coil with the smaller coil width is wound on the outer layer, and the winding method is uniform winding. The winding coil width is also equal to , so that the lengths of the primary side winding coil and the secondary side winding coil on the right side column are equal. Let the length of the magnetic powder core magnetic column on the right side be equal to the designed coil width of the right side column. .

[0118] Step S28: Calculate the electrical isolation distance between the inner and outer layer coils on the left and right sides according to the input voltage and output voltage of the transformer in the transformer design parameters.

[0119] It should be noted that based on the input voltage and output voltage of the transformer, determine the electrical isolation distance between the inner layer coil and the outer layer coil on the left side column and the electrical isolation distance between the inner layer coil and the outer layer coil on the right side column. .

[0120] Step 103: Calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch by using the pre-set transformer magnetic circuit model according to the number of turns of the primary and secondary side winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary side winding coils, and the transformer design parameters.

[0121] Specifically, step 103 may include the following sub-steps S31 - S34:

[0122] Step S31: Calculate the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary side winding coils allocated to the left and right side columns, the primary side resonance inductance value, the secondary side resonance inductance value, the primary side excitation inductance value of the transformer, and the total number of turns of the primary and secondary side winding coils in the transformer design parameters;

[0123] Step S32: Divide the pre-set transformer magnetic circuit model to generate the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch;

[0124] Step S33: Use the magnetic flux branch method to model based on the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch, and generate a system of relational equations between the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch;

[0125] Step S34: Use the system of relational equations between the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch, and calculate the magnetic flux of the magnetic flux branch according to the total magnetic resistance of the side column magnetic flux branch, the total magnetic resistance of the middle column magnetic flux branch, the total number of turns of the primary and secondary winding coils, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the primary winding coil current and the secondary winding coil current in the transformer design parameters.

[0126] It should be noted that, please refer to Figure 4 , the simplified magnetic circuit model of the transformer established by the present invention is as Figure 4 shown, the magnetic circuit is divided into three branches, including the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch. The magnetomotive force for magnetization on the left side column is , the magnetomotive force for demagnetization is , the magnetomotive force for magnetization on the right side column is , the magnetomotive force for demagnetization is , the total magnetic resistance of both side column magnetic flux branches is , the total magnetic resistance of the middle column magnetic flux branch is , is the magnetic flux of the left side column magnetic flux branch, is the magnetic flux of the middle column magnetic flux branch, is the magnetic flux of the right side column magnetic flux branch.

[0127] According to the magnetic flux branch method, the relational expressions between the magnetomotive force, magnetic resistance, and magnetic flux of the three magnetic flux branches can be listed, that is, the system of relational equations (4-1) between the left side column magnetic flux branch, the right side column magnetic flux branch, and the middle column magnetic flux branch:

[0128] (4-1)

[0129] Solving equation (4-1) can obtain the magnetic flux expressions (4-2) on the three magnetic flux branches:

[0130] (4-2)

[0131] Among them, after obtaining the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch, and then substituting the total number of turns of the primary and secondary winding coils, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the primary winding coil current and the secondary winding coil current in the transformer design parameters into equation (4-2) together, the magnetic flux of the magnetic flux branch can be obtained. The magnetic flux of the magnetic flux branch includes the magnetic flux of the left side column magnetic flux branch , the magnetic flux of the right side column magnetic flux branch and the magnetic flux of the middle column magnetic flux branch .

[0132] Furthermore, please refer to Figure 5 , the circuit model of the magnetic integrated transformer of the CLLC converter is as Figure 5 shown, where is the input voltage of the transformer, is the output voltage of the transformer. According to Faraday's law of electromagnetic induction, the expressions of the input and output voltages with respect to the number of winding turns and magnetic flux can be listed as Equation (4-3):

[0133] (4-3)

[0134] Substitute the expressions of and in Equation (4-2) into Equation (4-3) and simplify to obtain Equation (4-4):

[0135] (4-4)

[0136] Based on the above, the self-inductance of the primary winding coil , the self-inductance of the secondary winding coil and the mutual inductance of the primary and secondary coils can be obtained as Expression (4-5):

[0137] (4-5)

[0138] Furthermore, the exciting inductance of the primary side of the transformer , the primary resonance inductance and the secondary resonance inductance can be derived as Expression (4-6):

[0139] (4-6)

[0140] Finally, the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch are obtained as Expression (4-7):

[0141] (4-7)

[0142] Among them, by substituting the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the primary resonance inductance value, the secondary resonance inductance value, the primary excitation inductance value of the transformer, and the total number of turns of the primary and secondary winding coils in the transformer design parameters into Equation (4-7), the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch can be calculated; A is the total magnetic resistance parameter of the first side column; B is the total magnetic resistance parameter of the second side column; C is the total magnetic resistance parameter of the third side column; D is the total magnetic resistance parameter of the first middle column; E is the total magnetic resistance parameter of the second middle column; F is the total magnetic resistance parameter of the third middle column; G is the total magnetic resistance parameter of the fourth middle column; H is the total magnetic resistance parameter of the fifth middle column.

[0143] Step 104: Determine the precise middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the magnetic core structure.

[0144] It should be noted that the magnetic resistance of the middle column magnetic flux branch is controlled by opening an air gap. The magnetic resistivity of the air gap is much greater than that of the magnetic core. Therefore, although the length of the air gap is small, the magnetic field strength of the air gap is much greater than that of the magnetic core. The magnetic voltage drop across the air gap is large, resulting in a large magnetic potential difference at both ends of the air gap. The large magnetic potential difference will cause part of the magnetic flux to diffuse out of the magnetic core and flow in the air around the air gap, forming fringe flux. The existence of the fringe flux at the air gap will cause a large error in the calculation of the air gap magnetic resistance, bringing difficulties to controlling the total magnetic resistance of the middle column magnetic flux branch and affecting the design accuracy of the leakage inductance of the finally designed transformer.

[0145] Furthermore, please refer to Figure 6 , the equivalent model of the fringe flux near the middle column air gap is as shown in Figure 6 , where the air gap length is , the expansion width of the fringe flux on the side surface of the middle column of the magnetic core is m, and it is set that the expansion width is 3 times the air gap length, that is , the shape of the magnetic force line of the fringe flux is set as 1 / 4 ellipse + straight line + 1 / 4 ellipse, the ratio of the major axis to the minor axis of the ellipse is 2:1, the surface area of the fringe flux on the front and back side surfaces of the middle column of the magnetic core is , and the surface area on the left and right side surfaces is .

[0146] The shortest path and the longest path of the fringe flux on the side surface can be expressed by Equation (4-8):

[0147] (4-8)

[0148] The length coefficient K is calculated by Equation (4-9) as:

[0149] (4-9)

[0150] The surface area of the fringe flux on the front and back surfaces equivalent to the area on the cross-section of the air gap is and the surface area on the left and right surfaces equivalent to the area on the cross-section of the air gap is , and the expression (4-10) is as follows:

[0151] (4-10)

[0152] Calculate the reluctance magnitude of the air gap with a length of considering the fringe flux of the air gap which can be expressed as Equation (4-11):

[0153] (4-11)

[0154] where is the permeability of air.

[0155] Calculate the reluctance magnitude of the magnetic core magnetic path in the central leg flux branch in Equation (4-12) :

[0156] (4-12)

[0157] After arrangement, the total reluctance of the central leg flux branch is expressed as Equation (4-13):

[0158] (4-13)

[0159] where is the permeability of the magnetic core material of the EE-shaped magnetic core used.

[0160] Based on the above, finally, the total reluctance of the central leg flux branch corresponding to the accurate central leg air gap length is expressed as Equation (4-14):

[0161] (4-14)

[0162] where the total reluctance of the central leg flux branch, the height of the magnetic core window, the width of the central leg of the magnetic core, and the thickness of the magnetic core in the geometric parameters of the magnetic core structure are all substituted into Equation (4-14). Calculate the accurate central leg air gap length; a is the first accurate central leg air gap length parameter; b is the second accurate central leg air gap length parameter; c is the third accurate central leg air gap length parameter; d is the fourth accurate central leg air gap length parameter.

[0163] Step 105: Calculate the magnetic resistance at the magnetic core corners of the left and right side columns according to the magnetic core structure geometric parameters and the magnetic fluxes of the magnetic flux branches by using a preset magnetic core corner model.

[0164] The preset magnetic core corner model includes a left side column magnetic core corner model and a right side column magnetic core corner model.

[0165] The magnetic resistances at the magnetic core corners of the left and right side columns include the magnetic resistance at the magnetic core corner of the left side column and the magnetic resistance at the magnetic core corner of the right side column.

[0166] It should be noted that at the magnetic core corners of the side column magnetic flux branches, since the magnetic flux tends to flow in the path with the minimum magnetic resistance, that is, the shortest path, the magnetic flux is mainly concentrated at the inner corners. When the magnetic flux density at the inner corners approaches saturation, the magnetic resistance at the inner corners increases significantly, and the magnetic flux will flow from the corner with a larger radius. Therefore, the magnetic flux density distribution at the magnetic core corners is uneven, and the magnetic core material exhibits different magnetic permeabilities at different magnetic flux densities. If the uneven distribution of the magnetic flux at the corners is not considered, it will bring a large error to the calculation of the magnetic resistance at the magnetic core corners and affect the design accuracy of the leakage inductance of the finally designed transformer.

[0167] Specifically, step 105 may include the following sub-steps S51 - S55:

[0168] Step S51: Divide the left side column magnetic core corner model and the right side column magnetic core corner model respectively by using the width of the magnetic core side column in the magnetic core structure geometric parameters to determine the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side column magnetic core corner model and the right side column magnetic core corner model;

[0169] Step S52: Perform magnetic resistance operations on the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side column magnetic core corner model by using the magnetic flux of the left side column magnetic flux branch, the width of the magnetic core side column in the magnetic core structure geometric parameters and the thickness of the magnetic core to determine the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the left side column magnetic core corner model;

[0170] Step S53: Parallelly connect the magnetic resistances of the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side column magnetic core corner model to determine the magnetic resistance at the magnetic core corner of the left side column;

[0171] Step S54, using the magnetic flux of the right side column magnetic flux branch, the width of the core side column in the core structure geometric parameters, and the thickness of the core to perform magnetic resistance calculation on the first core corner area, the second core corner area, the third core corner area, and the corner area inside the core window corresponding to the right side column core corner model, to determine the magnetic resistance of the first core corner area, the second core corner area, the third core corner area, and the corner area inside the core window corresponding to the right side column core corner model;

[0172] Step S55, the magnetic resistance of the first core corner area, the magnetic resistance of the second core corner area, the magnetic resistance of the third core corner area and the magnetic resistance of the corner area in the core window corresponding to the right side column core corner model are connected in parallel to determine the magnetic resistance at the right side column core corner.

[0173] Please note that Figure 7 , establish a model for the corner of the transformer core, consider the uneven distribution of magnetic flux, and divide the magnetic flux at the corner of the core into five parts. The specific situation is as follows Figure 7 As shown, the corner length (i.e. the width of the core side column) of and A quarter arc is made at the corner, thereby dividing the corner into a quarter circle and two quarter rings and the remaining parts, which are respectively recorded as the first core corner area , the second core corner area , the third core corner area and the fourth core corner region , at the inner corner of the core window Make a quarter arc to get a quarter circle, which is recorded as the corner area inside the core window. ,set up , , and The magnetic fluxes flowing in are , , and , The magnetic flux in is negligible, where is the size of the magnetic flux of the side column magnetic flux branch, that is, the magnetic flux branch magnetic flux. This step uses the magnetic flux of the left side column magnetic flux branch and the magnetic flux of the right side column magnetic flux branch in the magnetic flux branch to perform calculations.

[0174] Furthermore, taking the geometric midline as the magnetic path length, we obtain the expression (4-15) for the cross-sectional area and magnetic path length of each region, where: , , , for , , and the cross-sectional areas of each region, , , , are , , and the magnetic path lengths of each region:

[0175] (4 - 15)

[0176] Calculate , , the magnitudes of the magnetic flux densities of each region (4 - 16):

[0177] (4 - 16)

[0178] According to the B - H curve of the magnetic core material used, obtain , , the accurate permeabilities of the regions at different magnetic flux densities respectively , and , that is, Equation (4 - 17), where is the function of the permeability with respect to the magnetic flux density obtained from the B - H curve of the magnetic core material.

[0179] (4 - 17)

[0180] Obtain , , , and the magnetic reluctance expressions of the regions (4 - 18):

[0181] (4 - 18)

[0182] Where is the accurate permeability of the region at the corresponding magnetic flux density ; is the accurate permeability of the region at the corresponding magnetic flux density ; is the accurate permeability of the region at the corresponding magnetic flux density ; is the air permeability.

[0183] Finally, the reluctances of all regions are connected in parallel to obtain the total reluctance at the core corner. (4-19):

[0184] (4-19)

[0185] Based on the above step principle, the reluctances at the core corners of the left side column are calculated respectively. and the reluctances at the core corners of the right side column. .

[0186] Step 106: Based on the core structure geometric parameters, the lengths of the magnetic powder core columns on the left and right sides, the magnetic fluxes of the magnetic flux branches, and the total reluctances of the side column magnetic flux branches, determine the reluctances of the magnetic powder core columns on the left and right sides and the magnetic permeabilities of the magnetic powder core materials of the magnetic powder core columns on the left and right sides.

[0187] The reluctances of the magnetic powder core columns on the left and right sides include the reluctances of the magnetic powder core column on the left side and the magnetic powder core column on the right side.

[0188] The magnetic permeabilities of the magnetic powder core materials of the magnetic powder core columns on the left and right sides include the magnetic permeabilities of the magnetic powder core materials of the magnetic powder core column on the left side and the magnetic powder core column on the right side.

[0189] Specifically, step 106 may include the following sub-steps S61-S65:

[0190] Step S61: Using the length of the magnetic powder core column on the left side, the length of the magnetic powder core column on the right side, the magnetic flux of the magnetic flux branch, the width of the core window, the height of the core window, the width of the core side column, and the thickness of the core in the core structure geometric parameters, calculate the reluctances of the left remaining core magnetic circuit and the right remaining core magnetic circuit;

[0191] Step S62: According to the reluctance of the left remaining core magnetic circuit and the total reluctance of the side column magnetic flux branch, calculate the reluctance of the magnetic powder core column on the left side;

[0192] Step S63: According to the reluctance of the right remaining core magnetic circuit and the total reluctance of the side column magnetic flux branch, calculate the reluctance of the magnetic powder core column on the right side;

[0193] Step S64: Based on the reluctance of the magnetic powder core column on the left side, the length of the magnetic powder core column on the left side, the width of the core side column and the thickness of the core in the core structure geometric parameters, calculate the magnetic permeability of the magnetic powder core material of the magnetic powder core column on the left side;

[0194] Step S65: Based on the reluctance of the magnetic powder core column on the right side, the length of the magnetic powder core column on the right side, the width of the core side column and the thickness of the core in the core structure geometric parameters, calculate the magnetic permeability of the magnetic powder core material of the magnetic powder core column on the right side.

[0195] It should be noted that the total magnetic resistance of the side column magnetic flux branch is composed of the magnetic resistance of the magnetic powder core column, the magnetic resistance at the two magnetic core corners, and the magnetic resistance of the remaining magnetic core magnetic circuit after subtracting the above two parts, which are connected in series.

[0196] First, calculate the magnetic resistance of the remaining magnetic core magnetic circuit of the left side column magnetic flux branch and the right side column magnetic flux branch after subtracting the magnetic powder core column and the two magnetic core corners (4-20):

[0197] (4-20)

[0198] The magnetic flux of the left side column magnetic flux branch obtained from Equation (4-2) 、the magnetic flux of the right side column magnetic flux branch , combined with the cross-sectional area of the side column ( ), the magnetic flux density of the left side column magnetic flux branch and the magnetic flux density of the right side column magnetic flux branch can be calculated: that is .

[0199] Among them, and are the accurate permeabilities according to the B-H curve of the magnetic core material at magnetic flux densities of and respectively, that is Equation (4-21). Among them, is the function of the permeability with respect to the magnetic flux density obtained from the B-H curve of the magnetic core material.

[0200] (4-21)

[0201] The magnetic resistance of the left magnetic powder core column and the magnetic resistance of the right magnetic powder core column are obtained by subtracting the magnetic resistance of the two magnetic core corners and the magnetic resistance of the remaining magnetic core magnetic circuit from the total magnetic resistance of the side column magnetic flux branch (4-22):

[0202] (4-22)

[0203] Calculate the permeability of the magnetic powder core material of the left magnetic powder core column and the right magnetic powder core column (4-23):

[0204] (4-23)

[0205] Step 107: Determine the primary leakage inductance in the target core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core columns according to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns, and the preset design leakage inductance.

[0206] It should be noted that there is a large magnetic potential difference at both ends of the magnetic powder core column surrounded by the winding coil, which will cause part of the magnetic flux to diffuse out of the core and form a loop in the air. This part of the magnetic flux does not fully link the primary winding coil and the secondary winding coil. According to the definition of leakage inductance, it is leakage inductance magnetic flux, which will bring an increase in the additional leakage inductance. If the leakage magnetic field energy in the air near the winding coil is not considered, it will affect the design accuracy of the leakage inductance of the finally designed transformer.

[0207] Specifically, step 107 may include the following sub-steps S71:

[0208] Step S71: Calculate the additional leakage inductance in the air near the initial winding coil by using the magnetic resistance of the left and right magnetic powder core columns, the magnetic flux of the magnetic flux branch, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the geometric parameters of the core structure, and the transformer design parameters.

[0209] Furthermore, step S71 may include the following sub-steps S711 - S715:

[0210] Step S711: Calculate the magnetic voltage drop at both ends of the left and right magnetic powder core columns by using the magnetic resistance of the left and right magnetic powder core columns and the magnetic flux of the magnetic flux branch.

[0211] Step S712: Calculate the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, and the magnetic field strength in the secondary winding coil of the left and right side columns according to the magnetic voltage drop at both ends of the left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, and the transformer design parameters.

[0212] Step S713: Calculate the total leakage inductance energy of the air in the winding coils of the left and right side columns by using the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, the magnetic field strength in the secondary winding coil of the left and right side columns, and the geometric parameters of the core structure.

[0213] Step S714: Determine the primary leakage inductance on the left side limb and the primary leakage inductance on the right side limb based on the total leakage inductance energy of the air in the left and right side limb winding coils and the transformer design parameters.

[0214] Step S715: Add the primary leakage inductance on the left side limb and the primary leakage inductance on the right side limb to determine the additional leakage inductance in the air near the initial winding coils.

[0215] The magnetic field intensity in the primary winding coils of the left and right side limbs includes the magnetic field intensity in the primary winding coil of the left side limb and the magnetic field intensity in the primary winding coil of the right side limb.

[0216] The magnetic field intensity in the electrical isolation layers of the left and right side limbs includes the magnetic field intensity in the electrical isolation layer of the left side limb and the magnetic field intensity in the electrical isolation layer of the right side limb.

[0217] The magnetic field intensity in the secondary winding coils of the left and right side limbs includes the magnetic field intensity in the secondary winding coil of the left side limb and the magnetic field intensity in the secondary winding coil of the right side limb.

[0218] The total leakage inductance energy of the air in the left and right side limb winding coils includes the total leakage inductance energy of the air near the left side limb winding coils and the total leakage inductance energy of the air near the right side limb winding coils.

[0219] It should be noted that considering the leakage magnetic field energy in the air near the winding coils, the additional leakage inductance in the air is calculated. Specifically, first calculate the magnetic voltage drops at both ends of the left and right magnetic powder core limbs. The magnetic voltage drops at both ends of the left and right magnetic powder core limbs include the magnetic voltage drop at both ends of the left magnetic powder core limb and the magnetic voltage drop at both ends of the right magnetic powder core limb (4 - 24):

[0220] (4 - 24)

[0221] Furthermore, please refer to Figure 8 , simplify the transformer structure. The structure diagram of the left side limb and the winding coils is as shown in Figure 8 , where the lengths of the primary winding coil, the secondary winding coil, and the magnetic powder core limb are equal and are , the wire diameter width of the primary winding coil is , the wire diameter width of the secondary winding coil is , and the electrical isolation distance between the primary winding coil and the secondary winding coil is .

[0222] Taking the side surface of the magnetic core as the reference point, defining x as the distance from the side surface of the magnetic core, according to Ampere's circuital law, the magnetic field intensity in the primary winding coil of the left side limb can be calculated as x increases , the magnetic field intensity in the electrical isolation layer of the left side column , the magnetic field intensity in the secondary winding coil of the left side column The expression for the variation with distance x is (4 - 25):

[0223] (4 - 25)

[0224] Integrating the magnetic field intensity according to the magnetic field energy formula, the leakage inductance energy stored in the primary winding coil of the left side column is obtained , the leakage inductance energy in the electrical isolation layer , the leakage inductance energy in the secondary winding coil and the total leakage inductance energy in the air near the winding coil of the left side column (4 - 26):

[0225] (4 - 26)

[0226] According to the relationship between magnetic field energy and inductance, the primary leakage inductance on the left side column is calculated (4 - 27):

[0227] (4 - 27)

[0228] It is worth mentioning that based on the above steps and principles for calculating the primary leakage inductance on the left side column, the primary leakage inductance on the right side column can be calculated .

[0229] Furthermore, adding the primary leakage inductance on the left side column and the primary leakage inductance on the right side column, the total additional primary leakage inductance in the air (i.e., the additional leakage inductance in the air near the initial winding coil) is finally obtained (4 - 28):

[0230] (4 - 28)

[0231] Step S72, based on the preset designed leakage inductance, determine the primary leakage inductance in the initial magnetic core magnetic circuit;

[0232] It should be noted that the primary leakage inductance in the magnetic core magnetic circuit is initialized by using the preset designed leakage inductance, that is, making the primary leakage inductance in the initial magnetic core magnetic circuit equal to the preset designed leakage inductance.

[0233] Step S73, finely adjust the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns to determine the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns;

[0234] Step S74: Update the magnetic resistance of the middle left and right magnetic powder core columns using the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns, the lengths of the left and right magnetic powder core columns, the width of the core side column in the transformer design parameters, and the thickness of the core, and determine the magnetic resistance of the middle left and right magnetic powder core columns;

[0235] Step S75: Update the primary leakage inductance in the initial core magnetic circuit using the total magnetic resistance of the side column magnetic flux branch, the magnetic resistance of the middle left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, and the total magnetic resistance of the middle column magnetic flux branch, and determine the primary leakage inductance in the middle core magnetic circuit;

[0236] Specifically, step S75 may include the following sub-steps:

[0237] Step S751: Update the total magnetic resistance of the side column magnetic flux branch using the magnetic resistance of the middle left and right magnetic powder core columns, and determine the total magnetic resistance of the middle side column magnetic flux branch;

[0238] Step S752: Update the primary leakage inductance in the initial core magnetic circuit according to the total magnetic resistance of the middle side column magnetic flux branch, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, and the total magnetic resistance of the middle column magnetic flux branch, and determine the primary leakage inductance in the middle core magnetic circuit.

[0239] It should be noted that based on the above steps, the additional primary leakage inductance in the air is calculated. At this time, the sum of the leakage inductance in the core and the leakage inductance in the air is greater than the designed leakage inductance. The magnetic resistance of the side column magnetic flux branch should be modulated (by adjusting the magnetic permeability of the magnetic powder core column) to reduce the leakage inductance in the core, so as to make the sum of the leakage inductance in the core and the leakage inductance in the air equal to the designed leakage inductance, thereby achieving precise control of the leakage inductance of the magnetic integrated transformer.

[0240] Furthermore, finely adjust the magnetic permeability of the left magnetic powder core column and the right magnetic powder core column to obtain the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns. The magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns includes the updated magnetic permeability of the left magnetic powder core column (i.e., the magnetic permeability of the magnetic powder core material of the middle left magnetic powder core column) and the magnetic permeability of the right magnetic powder core column (i.e., the magnetic permeability of the magnetic powder core material of the middle right magnetic powder core column) which are respectively and . Among them, the fine adjustment method is to subtract the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns from the set threshold value.

[0241] Calculate the magnetic resistance of the middle left and right magnetic powder core columns using the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns, the lengths of the left and right magnetic powder core columns, the width of the core side column in the transformer design parameters, and the thickness of the core. The magnetic resistance of the middle left and right magnetic powder core columns includes the magnetic resistance of the updated left magnetic powder core column (i.e., the magnetic resistance of the middle left magnetic powder core column) and the magnetic resistance of the right magnetic powder core magnetic column (i.e., the magnetic resistance of the middle right magnetic powder core magnetic column) (4 - 29):

[0242] (4 - 29)

[0243] Adopt the magnetic resistance of the middle left and right magnetic powder core magnetic columns to calculate the total magnetic resistance of the middle side column magnetic flux branch, that is, the updated total magnetic resistance of the side column magnetic flux branch (4 - 30):

[0244] (4 - 30)

[0245] Finally, based on the total magnetic resistance of the middle side column magnetic flux branch, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, and the total magnetic resistance of the middle column magnetic flux branch, calculate the primary leakage inductance in the middle magnetic core magnetic circuit, that is, the updated primary leakage inductance in the magnetic core magnetic circuit (4 - 31):

[0246] (4 - 31)

[0247] Step S76: Update the additional leakage inductance in the air near the initial winding coil based on the magnetic resistance of the middle left and right magnetic powder core magnetic columns, and determine the additional leakage inductance in the air near the middle winding coil;

[0248] It should be noted that, combined with equations (4 - 24) - (4 - 28), calculate the additional leakage inductance in the air near the middle winding coil according to the magnetic resistance of the middle left and right magnetic powder core magnetic columns, that is, the updated additional primary leakage inductance in the air .

[0249] Step S77: Determine whether the sum of the additional leakage inductance in the air near the middle winding coil and the primary leakage inductance in the middle magnetic core magnetic circuit is equal to the preset design leakage inductance;

[0250] Step S78: If so, use the additional leakage inductance in the air near the middle winding coil as the additional leakage inductance in the air near the target winding coil, use the primary leakage inductance in the middle magnetic core magnetic circuit as the primary leakage inductance in the target magnetic core magnetic circuit, and use the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core magnetic columns as the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core magnetic columns.

[0251] It should be noted that if the sum of the additional leakage inductance in the air near the intermediate winding coil and the primary leakage inductance in the magnetic circuit of the intermediate magnetic core is not equal to the preset design leakage inductance, then the magnetic permeability of the magnetic core material of the left and right magnetic powder core columns in the middle is used as the magnetic permeability of the magnetic core material of the new left and right magnetic powder core columns, the magnetic resistance of the left and right magnetic powder core columns in the middle is used as the magnetic resistance of the new left and right magnetic powder core columns, the primary leakage inductance in the magnetic circuit of the intermediate magnetic core is used as the primary leakage inductance in the new initial magnetic core magnetic circuit, the additional leakage inductance in the air near the intermediate winding coil is used as the additional leakage inductance in the air near the new initial winding coil, and jump to execute step S73 until the sum of the additional leakage inductance in the air near the intermediate winding coil and the primary leakage inductance in the magnetic circuit of the intermediate magnetic core is equal to the preset design leakage inductance. The additional leakage inductance in the air near the intermediate winding coil when the sum of the additional leakage inductance in the air near the intermediate winding coil and the primary leakage inductance in the magnetic circuit of the intermediate magnetic core is equal to the preset design leakage inductance is used as the additional leakage inductance in the air near the target winding coil, the primary leakage inductance in the magnetic circuit of the intermediate magnetic core is used as the primary leakage inductance in the target magnetic core magnetic circuit, and the magnetic permeability of the magnetic core material of the left and right magnetic powder core columns in the middle is used as the magnetic permeability of the magnetic core material of the target left and right magnetic powder core columns.

[0252] Step 108: Based on the preset coil winding method, design a magnetic integrated transformer for a CLLC converter through the sum of the primary leakage inductance in the target magnetic core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right magnetic powder core columns, the length of the precise middle column air gap, and the magnetic permeability of the magnetic core material of the target left and right magnetic powder core columns.

[0253] The preset coil winding method is to compare the primary winding coil and the secondary winding coil on the left side column. The coil with a larger coil width under tight winding is wound on the inner layer, the winding method is tight winding, and the winding coil width is , the coil with a smaller coil width is wound on the outer layer, the winding method is uniform winding, and the winding coil width is also equal to , so that the primary winding coil and the secondary winding coil on the left side column are of equal length; and compare the primary winding coil and the secondary winding coil on the right side column. The coil with a larger coil width under tight winding is wound on the inner layer, the winding method is tight winding, and the winding coil width is , the coil with a smaller coil width is wound on the outer layer, the winding method is uniform winding, and the winding coil width is also equal to , so that the primary winding coil and the secondary winding coil on the right side column are of equal length.

[0254] It should be noted that based on the preset coil winding method, the design of the magnetic integrated transformer for the CLLC converter is completed by considering the sum of the primary leakage inductance in the target core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the magnetic powder core columns on the left and right sides, the accurate air gap length of the middle column, and the magnetic permeability of the magnetic powder core material of the target magnetic powder core columns on the left and right sides.

[0255] As a comparison of technical effects, it can be referred to in combination with the existing technology. The working principle of the existing leakage inductance integration scheme is to unevenly distribute the primary winding and the secondary winding of the transformer to the two side columns respectively, which will generate a magnetic potential difference at both ends of the middle column. By adjusting the air gap magnetic resistance of the middle column and the two side columns, the magnitude of the magnetic flux flowing through the middle column can be controlled. According to the definition of leakage inductance, the magnetic flux in the middle column constitutes the leakage inductance flux. Therefore, by adjusting the air gap size between the middle core and the side cores and the number distribution of the primary and secondary windings on the two magnetic core side columns, the magnitude of the leakage inductance can be controlled. However, although this method can control the magnitude of the leakage inductance, the theoretical derivation results deviate greatly from the actual parameters, with a large error, and the precise control of the leakage inductance cannot be achieved. The reason is that the leakage magnetic flux in the air and the edge effect of the air gap are ignored, and the magnetic permeability of the magnetic core is considered to be infinite while ignoring the magnitude of the magnetic resistance in the magnetic core magnetic circuit.

[0256] Therefore, how to accurately model the air leakage magnetic flux, the air gap edge effect, and the magnetic resistance of the magnetic core magnetic circuit, and then fully consider their influence on the leakage inductance of the transformer, so as to achieve the precise control of the leakage inductance of the magnetic integrated transformer of the CLLC converter is an urgent problem to be solved.

[0257] In view of the above problems, the present invention proposes a design method for a magnetic integrated transformer for a CLLC converter, which fully considers the leakage magnetic flux in the air, the edge effect of the air gap, and the magnetic resistance of the magnetic core magnetic circuit, and proposes a design method for a magnetic integrated transformer of a CLLC converter with precisely controllable leakage inductance. (Using magnetic powder core columns equal in length to the winding coil to replace the air gap, and precisely controlling the total leakage inductance of the magnetic integrated transformer to be equal to the design value by controlling the magnetic permeability of the magnetic powder core material of the magnetic powder core columns), solving the problems of large design leakage inductance error and low accuracy. At the same time, by placing magnetic powder core columns equal in length to the winding coil in the side column magnetic flux branch, the magnetic resistance of the magnetic powder core column is equivalent to the internal resistance of the magnetic potential of the winding coil, so that most of the magnetic potential of the winding coil drops on the magnetic powder core column, reducing the magnetic potential difference at both ends of the magnetic powder core column and the leakage magnetic flux in the air, and further reducing the eddy current loss of the winding coil. In addition, by winding the primary winding coil and the secondary winding coil on the side column with equal length, and placing magnetic powder core columns equal in length to the winding coil, the distribution shape of the leakage magnetic flux in the air near the air gap is made more regular, reducing the difficulty of modeling and analyzing the leakage magnetic flux in the air, and facilitating the calculation of the magnitude of the leakage inductance in the air.

[0258] Compared with the prior art, the traditional CLLC converter adopts a discrete magnetic component solution, that is, an independent resonant inductor and an independent transformer are connected in series. This solution has problems such as large volume of magnetic components, low power density, large number of components, and high cost. Therefore, the present invention proposes a magnetic integration design method. By using the leakage inductance of the converter as the resonant inductor, the resonant inductor and the transformer are combined together, thus eliminating the independent resonant inductor, and having the advantages of small volume of magnetic components, high power density, small number of components, and low cost.

[0259] Secondly, as a component participating in resonance, the inductance value of the resonant inductor directly affects the accuracy of the resonant frequency of the resonant converter, and further affects the parameter design of the entire converter. Therefore, it is expected that the leakage inductance of the transformer can be controlled to obtain a more accurate inductance value. Therefore, the present invention proposes a magnetic integration design method with precise leakage inductance control. First, an accurate magnetic core magnetic circuit model and an air leakage inductance model are established, and then the accurate leakage inductance value of the transformer is calculated according to the models, so as to realize the precise control of the leakage inductance.

[0260] Thirdly, based on a design method of a magnetic integration transformer for a CLLC converter proposed by the present invention, the problems of numerous design parameters and great design difficulty of magnetic components are solved.

[0261] In an embodiment of the present invention, the present invention provides a method for designing a magnetically integrated transformer for a CLLC converter. First, obtain the transformer design parameters, and use the preset area product method to determine the total number of turns of the primary and secondary winding coils, the core model, and the geometric parameters of the core structure corresponding to the core model according to the transformer design parameters. Then, use the preset constraint conditions to determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side powder core magnetic columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters. Use the preset transformer magnetic circuit model to calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters. Determine the accurate middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the core structure. Use the preset core corner model to calculate the magnetic resistance at the core corners of the left and right side columns according to the geometric parameters of the core structure and the magnetic flux of the magnetic flux branch. Based on the geometric parameters of the core structure, the lengths of the left and right side powder core magnetic columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch, determine the magnetic resistance of the left and right side powder core magnetic columns and the magnetic permeability of the powder core material of the left and right side powder core magnetic columns. According to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right side powder core magnetic columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right side powder core magnetic columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, the magnetic permeability of the powder core material of the left and right side powder core magnetic columns, and the preset design leakage inductance, determine the primary side leakage inductance in the target core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the powder core material of the target left and right side powder core magnetic columns. Finally, based on the preset coil winding method, design a magnetically integrated transformer for a CLLC converter through the sum of the primary side leakage inductance in the target core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right side powder core magnetic columns, the accurate middle column air gap length, and the magnetic permeability of the powder core material of the target left and right side powder core magnetic columns. Based on the above solution, the present invention combines the preset coil winding method and the equal-length left and right side powder core magnetic column lengths, making the leakage magnetic flux distribution in the air near the winding coil more regular. At the same time, it also takes into account the core corners, the accurate middle column air gap length, and the additional air leakage inductance, thereby realizing the precise control of the transformer leakage inductance and improving the design accuracy of the magnetically integrated transformer for a CLLC converter.

[0262] For better illustration, refer to Figure 9, which shows a schematic flowchart of the magnetic integrated transformer design method provided in the second embodiment of the present invention for a CLLC converter. It should be noted that this embodiment only briefly describes the general process of the magnetic integrated transformer design method for a CLLC converter. The specific implementation process of each step can be understood by referring to the relevant content in the foregoing embodiments, and will not be elaborated here. It can be understood that the present invention places no restrictions on this.

[0263] Step 1: Obtain the design parameters of the transformer, calculate the magnetic core and winding coils according to the AP method, and obtain the structural geometric parameters of the magnetic core and the parameters of the winding coils.

[0264] Step 2: Calculate the number of turns of the primary and secondary winding coils respectively distributed on the left and right side columns, design the winding method of the coils, and obtain the length of the magnetic powder core magnetic column equal to the length of the coils.

[0265] Step 3: Calculate the total magnetic resistance of the magnetic flux branch of the two side columns and the total magnetic resistance of the magnetic flux branch of the middle column.

[0266] Step 4: Considering the edge magnetic flux effect of the air gap in the middle column, calculate the exact air gap size of the magnetic core middle column.

[0267] Step 5: Considering the uneven distribution of magnetic flux at the corners of the magnetic core, calculate the exact magnetic resistance size at the corners of the magnetic core.

[0268] Step 6: Subtract the magnetic resistance of the magnetic core magnetic path from the total magnetic resistance of the magnetic flux branch of the side column to obtain the magnetic resistance of the magnetic powder core magnetic column, and calculate the magnetic permeability of the magnetic powder core material of the magnetic powder core magnetic column.

[0269] Step 7: Considering the leakage magnetic field energy in the air near the winding coils, calculate the leakage inductance in the air.

[0270] Step 8: Fine-tune the magnetic permeability of the magnetic powder core material and perform iterative calculations repeatedly until the sum of the leakage inductance in the magnetic core and the leakage inductance in the air is equal to the designed leakage inductance.

[0271] In an embodiment of the present invention, a design method for a magnetically integrated transformer for a CLLC converter is proposed, which can precisely control the leakage inductance of the magnetically integrated transformer, so that the leakage inductance of the transformer acts as a resonant inductance to achieve magnetic integration. Specifically, in step 2, the optimal turn distribution method of the primary and secondary winding coils on the left and right side columns is derived. At the same time, in step S2, the winding method of the primary and secondary winding coils, that is, tightly winding the inner layer and evenly winding the outer layer, makes the lengths of the primary and secondary winding coils equal; placing a magnetic powder core magnetic column equal in length to the winding coil to control the magnetic resistance of the magnetic flux branch; the winding method of the coil and the equal-length magnetic powder core magnetic column make the leakage magnetic flux distribution in the space near the winding coil more regular, which is conducive to modeling and calculating the leakage inductance in the air. In step S3, the expressions for the total magnetic resistance of the magnetic flux branches of the left and right side columns and the total magnetic resistance of the magnetic flux branch of the middle column are derived. In step S4, the air gap length is controlled to control the magnitude of the total magnetic resistance of the middle column magnetic flux branch. Considering the edge magnetic flux near the air gap, the expression for the precise air gap length is derived. In step S5, considering the uneven distribution of magnetic flux at the core corner, a local model of the core corner is established to calculate the precise magnetic resistance at the core corner. In steps S7 and S8, a leakage magnetic energy model near the winding coil is established to calculate the leakage inductance in the air, and the magnetic permeability of the magnetic powder core magnetic column is finely adjusted and iteratively calculated until the sum of the leakage inductance in the core magnetic circuit and the leakage inductance in the air is equal to the designed leakage inductance.

[0272] Compared with the existing technology, the present invention fully considers the edge magnetic flux near the air gap, the magnetic resistance of the core magnetic circuit, the uneven distribution at the core corner, and the leakage inductance in the air near the winding coil, and establishes corresponding local models and derives mathematical formulas, so as to achieve precise control of the transformer leakage inductance. In contrast, the present invention improves the design accuracy.

[0273] By placing a magnetic powder core magnetic column equal in length to the winding coil in the side column magnetic flux branch, the magnetic resistance of the magnetic powder core magnetic column is equivalent to the internal resistance of the magnetomotive force of the winding coil, so that most of the magnetomotive force of the winding coil drops on the magnetic powder core magnetic column, reducing the magnetic potential difference at both ends of the magnetic powder core magnetic column and the leakage magnetic flux in the air, and further reducing the eddy current loss of the winding coil.

[0274] Please refer to Figure 10 , Figure 10 which is the structural block diagram of a design device for a magnetically integrated transformer for a CLLC converter provided in Embodiment 3 of the present invention.

[0275] A design device for a magnetically integrated transformer for a CLLC converter provided by the present invention includes:

[0276] An acquisition module 1001 is configured to acquire transformer design parameters, and determine the total number of turns of the primary and secondary winding coils, the core model, and the geometric parameters of the core structure corresponding to the core model according to the transformer design parameters by using a preset area product method;

[0277] A first calculation module 1002 is configured to determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters by using preset constraint conditions;

[0278] A second calculation module 1003 is configured to calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters by using a preset transformer magnetic circuit model;

[0279] A third calculation module 1004 is configured to determine the precise middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the core structure;

[0280] A fourth calculation module 1005 is configured to calculate the magnetic resistance at the magnetic core corners of the left and right side columns according to the geometric parameters of the core structure and the magnetic flux of the magnetic flux branch by using a preset magnetic core corner model;

[0281] A fifth calculation module 1006 is configured to determine the magnetic resistance of the left and right side magnetic powder core columns and the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns based on the geometric parameters of the core structure, the lengths of the left and right side magnetic powder core columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch;

[0282] An output target parameter module 1007 is configured to determine the primary side leakage inductance in the target magnetic core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns according to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right side magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right side magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns, and a preset design leakage inductance;

[0283] A design module 1008 is configured to design a magnetic integrated transformer for a CLLC converter based on a preset coil winding method, the sum of the primary side leakage inductance in the target magnetic core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right side magnetic powder core columns, the precise middle column air gap length, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns.

[0284] Further, the preset constraint conditions are specifically:

[0285] The product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the left side pillar is equal to the product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the right side pillar.

[0286] Furthermore, the number of turns of the primary and secondary winding coils allocated to the left and right side pillars includes the number of turns of the primary winding coil of the left side pillar, the number of turns of the secondary winding coil of the left side pillar, the number of turns of the primary winding coil of the right side pillar, and the number of turns of the secondary winding coil of the right side pillar; the lengths of the left and right magnetic powder core pillars include the length of the left magnetic powder core pillar and the length of the right magnetic powder core pillar; the first calculation module 1002 is specifically used for:

[0287] According to the preset constraint conditions and the inductance values of the primary resonance inductance and the secondary resonance inductance in the transformer design parameters, calculate the number of turns of the primary winding coil of the left side pillar, the number of turns of the secondary winding coil of the left side pillar, the number of turns of the primary winding coil of the right side pillar, and the number of turns of the secondary winding coil of the right side pillar;

[0288] Based on the number of turns of the primary winding coil of the left side pillar and the number of turns of the secondary winding coil of the left side pillar, determine the width of the primary winding coil of the left side pillar and the width of the secondary winding coil of the left side pillar under the condition of tight winding;

[0289] Compare the width of the primary winding coil of the left side pillar and the width of the secondary winding coil of the left side pillar under the condition of tight winding;

[0290] Take the maximum width of the primary winding coil of the left side pillar or the width of the secondary winding coil of the left side pillar as the target width of the left side pillar winding coil, and based on the target width of the left side pillar winding coil, determine the length of the left magnetic powder core pillar;

[0291] Based on the number of turns of the primary winding coil of the right side pillar and the number of turns of the secondary winding coil of the right side pillar, determine the width of the primary winding coil of the right side pillar and the width of the secondary winding coil of the right side pillar under the condition of tight winding;

[0292] Compare the width of the primary winding coil of the right side pillar and the width of the secondary winding coil of the right side pillar under the condition of tight winding;

[0293] Take the maximum width of the primary winding coil of the right side pillar or the width of the secondary winding coil of the right side pillar as the target width of the right side pillar winding coil, and based on the target width of the right side pillar winding coil, determine the length of the right magnetic powder core pillar;

[0294] According to the input voltage and output voltage of the transformer in the transformer design parameters, calculate the electrical isolation distance between the inner and outer layer coils on the left and right sides.

[0295] Furthermore, the second calculation module 1003 is specifically used for:

[0296] Calculate the total magnetic resistance of the side-leg flux branches and the total magnetic resistance of the central-leg flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side legs, the primary resonant inductance value, the secondary resonant inductance value, the primary exciting inductance value of the transformer, and the total number of turns of the primary and secondary winding coils in the transformer design parameters;

[0297] Divide the preset transformer magnetic circuit model to generate the left side-leg flux branch, the right side-leg flux branch, and the central-leg flux branch;

[0298] Use the flux-branch method to model according to the left side-leg flux branch, the right side-leg flux branch, and the central-leg flux branch to generate a system of relational equations between the left side-leg flux branch, the right side-leg flux branch, and the central-leg flux branch;

[0299] Use the system of relational equations between the left side-leg flux branch, the right side-leg flux branch, and the central-leg flux branch to calculate the flux of the flux branches according to the total magnetic resistance of the side-leg flux branches, the total magnetic resistance of the central-leg flux branch, the total number of turns of the primary and secondary winding coils, the number of turns of the primary and secondary winding coils allocated to the left and right side legs, the current of the primary winding coil and the current of the secondary winding coil in the transformer design parameters;

[0300] The corresponding calculation formulas for the total magnetic resistance of the side-leg flux branches and the total magnetic resistance of the central-leg flux branch are specifically:

[0301] ;

[0302] Among them, A is the total magnetic resistance parameter of the first side leg; B is the total magnetic resistance parameter of the second side leg; C is the total magnetic resistance parameter of the third side leg; D is the total magnetic resistance parameter of the first central leg; E is the total magnetic resistance parameter of the second central leg; F is the total magnetic resistance parameter of the third central leg; G is the total magnetic resistance parameter of the fourth central leg; H is the total magnetic resistance parameter of the fifth central leg; is the total magnetic resistance of the side-leg flux branches; is the total magnetic resistance of the central-leg flux branch; is the value of the primary resonant inductance; is the value of the secondary resonant inductance; is the number of turns of the primary winding coil allocated to the left side leg; is the number of turns of the secondary winding coil allocated to the left side leg; is the total number of turns of the secondary winding coil; is the total number of turns of the primary winding coil; is the number of turns of the primary winding coil allocated to the right side leg; is the number of turns of the secondary winding coil allocated to the right side leg; is the primary exciting inductance value of the transformer.

[0303] Further, the magnetic flux of the magnetic flux branch includes the magnetic flux of the left side column magnetic flux branch and the magnetic flux of the right side column magnetic flux branch; the preset magnetic core corner model includes the left side column magnetic core corner model and the right side column magnetic core corner model; the magnetic resistance at the magnetic core corners of the left and right side columns includes the magnetic resistance at the magnetic core corner of the left side column and the magnetic resistance at the magnetic core corner of the right side column; the fourth calculation module 1005 is specifically configured to:

[0304] Use the width of the magnetic core side column in the magnetic core structure geometric parameters to divide the left side column magnetic core corner model and the right side column magnetic core corner model respectively, and determine the first magnetic core corner area, the second magnetic core corner area, the third magnetic core corner area and the inner corner area of the magnetic core window corresponding to the left side column magnetic core corner model and the right side column magnetic core corner model;

[0305] Perform magnetic resistance operations on the first magnetic core corner area, the second magnetic core corner area, the third magnetic core corner area and the inner corner area of the magnetic core window corresponding to the left side column magnetic core corner model by using the magnetic flux of the left side column magnetic flux branch, the width of the magnetic core side column in the magnetic core structure geometric parameters and the thickness of the magnetic core, and determine the magnetic resistance of the first magnetic core corner area, the magnetic resistance of the second magnetic core corner area, the magnetic resistance of the third magnetic core corner area and the magnetic resistance of the inner corner area of the magnetic core window corresponding to the left side column magnetic core corner model;

[0306] Parallelly connect the magnetic resistance of the first magnetic core corner area, the magnetic resistance of the second magnetic core corner area, the magnetic resistance of the third magnetic core corner area and the magnetic resistance of the inner corner area of the magnetic core window corresponding to the left side column magnetic core corner model to determine the magnetic resistance at the magnetic core corner of the left side column;

[0307] Perform magnetic resistance operations on the first magnetic core corner area, the second magnetic core corner area, the third magnetic core corner area and the inner corner area of the magnetic core window corresponding to the right side column magnetic core corner model by using the magnetic flux of the right side column magnetic flux branch, the width of the magnetic core side column in the magnetic core structure geometric parameters and the thickness of the magnetic core, and determine the magnetic resistance of the first magnetic core corner area, the magnetic resistance of the second magnetic core corner area, the magnetic resistance of the third magnetic core corner area and the magnetic resistance of the inner corner area of the magnetic core window corresponding to the right side column magnetic core corner model;

[0308] Parallelly connect the magnetic resistance of the first magnetic core corner area, the magnetic resistance of the second magnetic core corner area, the magnetic resistance of the third magnetic core corner area and the magnetic resistance of the inner corner area of the magnetic core window corresponding to the right side column magnetic core corner model to determine the magnetic resistance at the magnetic core corner of the right side column.

[0309] Further, the magnetic resistance of the left and right magnetic powder core magnetic columns includes the magnetic resistance of the left magnetic powder core magnetic column and the magnetic resistance of the right magnetic powder core magnetic column; the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core magnetic columns includes the magnetic permeability of the magnetic powder core material of the left magnetic powder core magnetic column and the magnetic permeability of the magnetic powder core material of the right magnetic powder core magnetic column; the fifth calculation module 1006 is specifically configured to:

[0310] Calculate the reluctance of the left remaining core magnetic path and the reluctance of the right remaining core magnetic path using the length of the left magnetic powder core column, the length of the right magnetic powder core column, the magnetic flux of the magnetic flux branch, and the geometric parameters of the core structure, including the width of the core window, the height of the core window, the width of the core side column, and the thickness of the core.

[0311] Calculate the reluctance of the left magnetic powder core column based on the reluctance of the left remaining core magnetic path and the total reluctance of the side column magnetic flux branch.

[0312] Calculate the reluctance of the right magnetic powder core column based on the reluctance of the right remaining core magnetic path and the total reluctance of the side column magnetic flux branch.

[0313] Calculate the magnetic permeability of the magnetic powder core material of the left magnetic powder core column based on the reluctance of the left magnetic powder core column, the length of the left magnetic powder core column, the width of the core side column, and the thickness of the core in the geometric parameters of the core structure.

[0314] Calculate the magnetic permeability of the magnetic powder core material of the right magnetic powder core column based on the reluctance of the right magnetic powder core column, the length of the right magnetic powder core column, the width of the core side column, and the thickness of the core in the geometric parameters of the core structure.

[0315] Furthermore, the output target parameter module 1007 includes:

[0316] The first sub-module is used to calculate the additional leakage inductance in the air near the initial winding coil using the reluctance of the left and right magnetic powder core columns, the magnetic flux of the magnetic flux branch, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the length of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the geometric parameters of the core structure, and the transformer design parameters.

[0317] The second sub-module is used to determine the primary leakage inductance in the initial core magnetic path based on the preset design leakage inductance.

[0318] The third sub-module is used to finely adjust the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns to determine the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns.

[0319] The fourth sub-module is used to update the reluctance of the left and right magnetic powder core columns using the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core columns, the length of the left and right magnetic powder core columns, the width of the core side column, and the thickness of the core in the transformer design parameters to determine the reluctance of the middle left and right magnetic powder core columns.

[0320] The fifth sub-module is used to update the primary leakage inductance in the initial core magnetic path using the total reluctance of the side column magnetic flux branch, the reluctance of the middle left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, and the total reluctance of the middle column magnetic flux branch to determine the primary leakage inductance in the middle core magnetic path.

[0321] The sixth sub-module is used to update the additional leakage inductance in the air near the initial winding coil based on the magnetic resistance of the middle left and right magnetic powder core magnetic columns, and determine the additional leakage inductance in the air near the middle winding coil;

[0322] The seventh sub-module is used to determine whether the sum of the additional leakage inductance in the air near the middle winding coil and the primary side leakage inductance in the middle magnetic core magnetic circuit is equal to the preset design leakage inductance;

[0323] The eighth sub-module is used to, if so, use the additional leakage inductance in the air near the middle winding coil as the additional leakage inductance in the air near the target winding coil, use the primary side leakage inductance in the middle magnetic core magnetic circuit as the primary side leakage inductance in the target magnetic core magnetic circuit, and use the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core magnetic columns as the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core magnetic columns.

[0324] Further, the first sub-module is specifically used for:

[0325] Calculate the magnetic voltage drop at both ends of the left and right magnetic powder core magnetic columns by using the magnetic resistance of the left and right magnetic powder core magnetic columns and the magnetic flux of the magnetic flux branch;

[0326] Calculate the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, and the magnetic field strength in the secondary winding coil of the left and right side columns according to the magnetic voltage drop at both ends of the left and right magnetic powder core magnetic columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the length of the left and right magnetic powder core magnetic columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, and the transformer design parameters;

[0327] Calculate the total air leakage inductance energy of the left and right side column winding coils by using the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, the magnetic field strength in the secondary winding coil of the left and right side columns, and the geometric parameters of the magnetic core structure;

[0328] Determine the primary side leakage inductance on the left side column and the primary side leakage inductance on the right side column based on the total air leakage inductance energy of the left and right side column winding coils and the transformer design parameters;

[0329] Add the primary side leakage inductance on the left side column and the primary side leakage inductance on the right side column to determine the additional leakage inductance in the air near the initial winding coil.

[0330] Further, the accurate middle column air gap length is specifically:

[0331] ;

[0332] Wherein, is the accurate middle column air gap length; is the total magnetic resistance of the central column magnetic flux branch; a is the first precise central column air gap length parameter; b is the second precise central column air gap length parameter; c is the third precise central column air gap length parameter; d is the fourth precise central column air gap length parameter; is the height of the magnetic core window; is the width of the central column of the magnetic core; is the thickness of the magnetic core; is the magnetic permeability of the magnetic core material of the EE-type magnetic core used; is the air magnetic permeability.

[0333] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described devices, modules, and sub-modules can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0334] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or equivalently replace some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic integration transformer design method for a CLLC converter, characterized in that, Including: Obtain the transformer design parameters, and use the preset area product method to determine the total number of turns of the primary and secondary winding coils, the core model, and the geometric parameters of the core structure corresponding to the core model according to the transformer design parameters; Determine the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters by using the preset constraint conditions; Calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters by using the preset transformer magnetic circuit model; Determine the precise air gap length of the middle column according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the core structure; Calculate the magnetic resistance at the magnetic core corners of the left and right side columns according to the geometric parameters of the core structure and the magnetic flux of the magnetic flux branch by using the preset magnetic core corner model; Determine the magnetic resistance of the left and right side magnetic powder core columns and the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns based on the geometric parameters of the core structure, the lengths of the left and right side magnetic powder core columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch; Determine the primary leakage inductance in the target magnetic core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns according to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right side magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right side magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right side coils, the magnetic permeability of the magnetic powder core material of the left and right side magnetic powder core columns, and the preset design leakage inductance; Design a magnetic integrated transformer for a CLLC converter based on the preset coil winding method, the sum of the primary leakage inductance in the target magnetic core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right side magnetic powder core columns, the precise air gap length of the middle column, and the magnetic permeability of the magnetic powder core material of the target left and right side magnetic powder core columns.

2. The method for designing a magnetically integrated transformer for a CLLC converter according to claim 1, wherein The preset constraint conditions are specifically: The product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the left side column is equal to the product of the number of turns of the primary winding coil and the number of turns of the secondary winding coil allocated to the right side column.

3. The design method of the magnetic integrated transformer for the CLLC converter according to claim 1, characterized in that The number of turns of the primary and secondary winding coils allocated to the left and right side columns includes the number of turns of the primary winding coil of the left side column, the number of turns of the secondary winding coil of the left side column, the number of turns of the primary winding coil of the right side column, and the number of turns of the secondary winding coil of the right side column; the lengths of the left and right side magnetic powder core columns include the length of the left side magnetic powder core column and the length of the right side magnetic powder core column; the step of determining the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right side magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right side coils according to the transformer design parameters by using the preset constraint conditions includes: Using preset constraint conditions, calculate the number of turns of the primary winding coil of the left side column, the number of turns of the secondary winding coil of the left side column, the number of turns of the primary winding coil of the right side column, and the number of turns of the secondary winding coil of the right side column according to the primary resonance inductance value and the secondary resonance inductance value in the transformer design parameters; Based on the number of turns of the primary winding coil of the left side column and the number of turns of the secondary winding coil of the left side column, determine the width of the primary winding coil of the left side column and the width of the secondary winding coil of the left side column in the case of tight winding; Compare the width of the primary winding coil of the left side column and the width of the secondary winding coil of the left side column in the case of tight winding; Take the maximum of the width of the primary winding coil of the left side column or the width of the secondary winding coil of the left side column as the target width of the winding coil of the left side column, and determine the length of the magnetic powder core column of the left side based on the target width of the winding coil of the left side column; Based on the number of turns of the primary winding coil of the right side column and the number of turns of the secondary winding coil of the right side column, determine the width of the primary winding coil of the right side column and the width of the secondary winding coil of the right side column in the case of tight winding; Compare the width of the primary winding coil of the right side column and the width of the secondary winding coil of the right side column in the case of tight winding; Take the maximum of the width of the primary winding coil of the right side column or the width of the secondary winding coil of the right side column as the target width of the winding coil of the right side column, and determine the length of the magnetic powder core column of the right side based on the target width of the winding coil of the right side column; Calculate the electrical isolation distance between the inner and outer layers of the coils on the left and right sides according to the input voltage and output voltage of the transformer in the transformer design parameters.

4. The design method of the magnetic integrated transformer for the CLLC converter according to claim 1, wherein The method of using a preset transformer magnetic circuit model to calculate the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the total number of turns of the primary and secondary winding coils and the transformer design parameters includes: Calculate the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the primary resonance inductance value, the secondary resonance inductance value, the primary excitation inductance value of the transformer, and the total number of turns of the primary and secondary winding coils in the transformer design parameters; Divide the preset transformer magnetic circuit model to generate a left side column magnetic flux branch, a right side column magnetic flux branch and a middle column magnetic flux branch; Use the magnetic flux branch method to model according to the left side column magnetic flux branch, the right side column magnetic flux branch and the middle column magnetic flux branch to generate a relationship equation set between the left side column magnetic flux branch, the right side column magnetic flux branch and the middle column magnetic flux branch; Use the relationship equation set between the left side column magnetic flux branch, the right side column magnetic flux branch and the middle column magnetic flux branch to calculate the magnetic flux of the magnetic flux branch according to the total magnetic resistance of the side column magnetic flux branch, the total magnetic resistance of the middle column magnetic flux branch, the total number of turns of the primary and secondary winding coils, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the primary winding coil current and the secondary winding coil current in the transformer design parameters; The calculation formulas corresponding to the total magnetic resistance of the side column magnetic flux branch and the total magnetic resistance of the middle column magnetic flux branch are specifically as follows: ； Among them, A is the total magnetic reluctance parameter of the first side column; B is the total magnetic reluctance parameter of the second side column; C is the total magnetic reluctance parameter of the third side column; D is the total magnetic reluctance parameter of the first middle column; E is the total magnetic reluctance parameter of the second middle column; F is the total magnetic reluctance parameter of the third middle column; G is the total magnetic reluctance parameter of the fourth middle column; H is the total magnetic reluctance parameter of the fifth middle column; is the total magnetic reluctance of the side column magnetic flux branch; is the total magnetic reluctance of the middle column magnetic flux branch; is the primary resonant inductance value; is the secondary resonant inductance value; is the number of turns of the primary winding coil allocated to the left side column; is the number of turns of the secondary winding coil allocated to the left side column; is the total number of turns of the secondary winding coil; is the total number of turns of the primary winding coil; is the number of turns of the primary winding coil allocated to the right side column; is the number of turns of the secondary winding coil allocated to the right side column; is the primary exciting inductance value of the transformer.

5. The method for designing a magnetically integrated transformer for a CLLC converter according to claim 1, characterized in that, The magnetic flux of the magnetic flux branch includes the magnetic flux of the left side column magnetic flux branch and the magnetic flux of the right side column magnetic flux branch; the preset magnetic core corner model includes the left side column magnetic core corner model and the right side column magnetic core corner model; the magnetic resistance at the magnetic core corners of the left and right side columns includes the magnetic resistance at the magnetic core corner of the left side column and the magnetic resistance at the magnetic core corner of the right side column; the method of using the preset magnetic core corner model to calculate the magnetic resistance at the magnetic core corners of the left and right side columns according to the geometric parameters of the magnetic core structure and the magnetic flux of the magnetic flux branch includes: Using the width of the magnetic core side column in the geometric parameters of the magnetic core structure to divide the left side column magnetic core corner model and the right side column magnetic core corner model respectively, and determining the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side column magnetic core corner model and the right side column magnetic core corner model; Performing magnetic resistance operations on the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the left side column magnetic core corner model by using the magnetic flux of the left side column magnetic flux branch, the width of the magnetic core side column and the thickness of the magnetic core in the geometric parameters of the magnetic core structure, and determining the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the left side column magnetic core corner model; Parallelly connecting the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the left side column magnetic core corner model to determine the magnetic resistance at the magnetic core corner of the left side column; Performing magnetic resistance operations on the first magnetic core corner region, the second magnetic core corner region, the third magnetic core corner region and the magnetic core window inner corner region corresponding to the right side column magnetic core corner model by using the magnetic flux of the right side column magnetic flux branch, the width of the magnetic core side column and the thickness of the magnetic core in the geometric parameters of the magnetic core structure, and determining the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the right side column magnetic core corner model; Parallelly connecting the magnetic resistance of the first magnetic core corner region, the magnetic resistance of the second magnetic core corner region, the magnetic resistance of the third magnetic core corner region and the magnetic resistance of the magnetic core window inner corner region corresponding to the right side column magnetic core corner model to determine the magnetic resistance at the magnetic core corner of the right side column.

6. The method for designing a magnetically integrated transformer for a CLLC converter according to claim 3, wherein, The magnetic resistance of the left and right magnetic powder core magnetic columns includes the magnetic resistance of the left magnetic powder core magnetic column and the magnetic resistance of the right magnetic powder core magnetic column; the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core magnetic columns includes the magnetic permeability of the magnetic powder core material of the left magnetic powder core magnetic column and the magnetic permeability of the magnetic powder core material of the right magnetic powder core magnetic column; the method of determining the magnetic resistance of the left and right magnetic powder core magnetic columns and the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core magnetic columns based on the geometric parameters of the magnetic core structure, the lengths of the left and right magnetic powder core magnetic columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branch includes: Calculate the magnetic resistance of the left remaining core magnetic path and the magnetic resistance of the right remaining core magnetic path by using the length of the left magnetic powder core magnetic column, the length of the right magnetic powder core magnetic column, the magnetic flux of the magnetic flux branch, and the geometric parameters of the core structure, including the width of the core window, the height of the core window, the width of the core side column, and the thickness of the core. Calculate the magnetic resistance of the left magnetic powder core magnetic column according to the magnetic resistance of the left remaining core magnetic path and the total magnetic resistance of the side column magnetic flux branch. Calculate the magnetic resistance of the right magnetic powder core magnetic column according to the magnetic resistance of the right remaining core magnetic path and the total magnetic resistance of the side column magnetic flux branch. Calculate the magnetic permeability of the magnetic powder core material of the left magnetic powder core magnetic column based on the magnetic resistance of the left magnetic powder core magnetic column, the length of the left magnetic powder core magnetic column, the width of the core side column, and the thickness of the core in the geometric parameters of the core structure. Calculate the magnetic permeability of the magnetic powder core material of the right magnetic powder core magnetic column based on the magnetic resistance of the right magnetic powder core magnetic column, the length of the right magnetic powder core magnetic column, the width of the core side column, and the thickness of the core in the geometric parameters of the core structure.

7. The design method of the magnetically integrated transformer for the CLLC converter according to claim 6, wherein Determine the primary leakage inductance in the target core magnetic path, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core magnetic columns according to the total magnetic resistance of the side column magnetic flux branch, the geometric parameters of the core structure, the total magnetic resistance of the middle column magnetic flux branch, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right magnetic powder core magnetic columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right magnetic powder core magnetic columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core magnetic columns, and the preset design leakage inductance, including: Calculate the additional leakage inductance in the air near the initial winding coil by using the magnetic resistance of the left and right magnetic powder core magnetic columns, the magnetic flux of the magnetic flux branch, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the lengths of the left and right magnetic powder core magnetic columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the geometric parameters of the core structure, and the transformer design parameters. Determine the primary leakage inductance in the initial core magnetic path based on the preset design leakage inductance. Fine-tune the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core magnetic columns to determine the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core magnetic columns. Update the magnetic resistance of the left and right magnetic powder core magnetic columns by using the magnetic permeability of the magnetic powder core material of the middle left and right magnetic powder core magnetic columns, the lengths of the left and right magnetic powder core magnetic columns, the width of the core side column, and the thickness of the core in the transformer design parameters to determine the magnetic resistance of the middle left and right magnetic powder core magnetic columns. Update the primary leakage inductance in the initial core magnetic path by using the total magnetic resistance of the side column magnetic flux branch, the magnetic resistance of the middle left and right magnetic powder core magnetic columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, and the total magnetic resistance of the middle column magnetic flux branch to determine the primary leakage inductance in the middle core magnetic path. Update the additional leakage inductance in the air near the initial winding coil based on the magnetic resistance of the middle left and right magnetic powder core magnetic columns to determine the additional leakage inductance in the air near the middle winding coil. Determine whether the sum of the additional leakage inductance in the air near the intermediate winding coil and the primary leakage inductance in the magnetic circuit of the intermediate magnetic core is equal to the preset designed leakage inductance; If so, use the additional leakage inductance in the air near the intermediate winding coil as the additional leakage inductance in the air near the target winding coil, use the primary leakage inductance in the magnetic circuit of the intermediate magnetic core as the primary leakage inductance in the magnetic circuit of the target magnetic core, and use the magnetic permeability of the magnetic powder core material of the intermediate left and right magnetic powder core columns as the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core columns.

8. The method for designing a magnetically integrated transformer for a CLLC converter according to claim 7, wherein Calculating the additional leakage inductance in the air near the initial winding coil by using the magnetic resistance of the left and right magnetic powder core columns, the magnetic flux of the magnetic flux branch, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the length of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the geometric parameters of the magnetic core structure, and the transformer design parameters includes: Using the magnetic resistance of the left and right magnetic powder core columns and the magnetic flux of the magnetic flux branch to calculate the magnetic voltage drop at both ends of the left and right magnetic powder core columns; According to the magnetic voltage drop at both ends of the left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the length of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, and the transformer design parameters, calculate the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, and the magnetic field strength in the secondary winding coil of the left and right side columns; Using the magnetic field strength in the primary winding coil of the left and right side columns, the magnetic field strength in the electrical isolation layer of the left and right side columns, the magnetic field strength in the secondary winding coil of the left and right side columns, and the geometric parameters of the magnetic core structure, calculate the total leakage inductance energy of the air in the winding coils of the left and right side columns; Based on the total leakage inductance energy of the air in the winding coils of the left and right side columns and the transformer design parameters, determine the primary leakage inductance on the left side column and the primary leakage inductance on the right side column; Add the primary leakage inductance on the left side column and the primary leakage inductance on the right side column to determine the additional leakage inductance in the air near the initial winding coil.

9. The method for designing a magnetically integrated transformer for a CLLC converter according to claim 1, characterized in that The precise middle column air gap length is specifically: ； Among them, is the precise middle-leg air-gap length; is the total magnetic reluctance of the middle-leg magnetic-flux branch; a is the first precise middle-leg air-gap length parameter; b is the second precise middle-leg air-gap length parameter; c is the third precise middle-leg air-gap length parameter; d is the fourth precise middle-leg air-gap length parameter; is the height of the magnetic-core window; is the width of the middle-leg of the magnetic core; is the thickness of the magnetic core; is the magnetic permeability of the magnetic-core material of the EE-type magnetic core used; is the magnetic permeability of air.

10. A magnetic integrated transformer design device for a CLLC converter, characterized in that, Including: An acquisition module for acquiring transformer design parameters and determining the total number of turns of the primary and secondary winding coils, the magnetic core model, and the geometric parameters of the magnetic core structure corresponding to the magnetic core model according to the transformer design parameters by using the preset area product method; A first calculation module for determining the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the length of the left and right magnetic powder core columns, and the electrical isolation distance between the inner and outer layers of the left and right coils according to the transformer design parameters by using the preset constraint conditions; A second calculation module for calculating the magnetic flux of the magnetic flux branch, the total magnetic resistance of the side column magnetic flux branch, and the total magnetic resistance of the middle column magnetic flux branch according to the number of turns of the primary and secondary winding coils distributed to the left and right side columns, the total number of turns of the primary and secondary winding coils, and the transformer design parameters by using the preset transformer magnetic circuit model; A third calculation module for determining the precise middle column air gap length according to the total magnetic resistance of the middle column magnetic flux branch and the geometric parameters of the magnetic core structure; A fourth calculation module, configured to calculate the magnetic resistance at the magnetic core corners of the left and right side columns according to the magnetic core structure geometric parameters and the magnetic flux of the magnetic flux branch by using a preset magnetic core corner model; A fifth calculation module, configured to determine the magnetic resistance of the left and right magnetic powder core columns and the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns based on the magnetic core structure geometric parameters, the lengths of the left and right magnetic powder core columns, the magnetic flux of the magnetic flux branch, and the total magnetic resistance of the side column magnetic flux branches; An output target parameter module, configured to determine the primary leakage inductance in the target magnetic core magnetic circuit, the additional leakage inductance in the air near the target winding coil, and the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core columns according to the total magnetic resistance of the side column magnetic flux branches, the magnetic core structure geometric parameters, the total magnetic resistance of the middle column magnetic flux branches, the magnetic flux of the magnetic flux branch, the magnetic resistance of the left and right magnetic powder core columns, the number of turns of the primary and secondary winding coils allocated to the left and right side columns, the transformer design parameters, the lengths of the left and right magnetic powder core columns, the electrical isolation distance between the inner and outer layers of the left and right coils, the magnetic permeability of the magnetic powder core material of the left and right magnetic powder core columns, and a preset design leakage inductance; A design module, configured to design a magnetic integrated transformer for a CLLC converter based on a preset coil winding method, by using the sum of the primary leakage inductance in the target magnetic core magnetic circuit and the additional leakage inductance in the air near the target winding coil, the lengths of the left and right magnetic powder core columns, the precise middle column air gap length, and the magnetic permeability of the magnetic powder core material of the target left and right magnetic powder core columns.

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