Transformer magnetic integration structure integrating double direct-current inductors and leakage inductors and integration method of transformer magnetic integration structure

Abstract

The invention discloses a transformer magnetic integration structure integrating double direct current inductors and leakage inductors and an integration method of the transformer magnetic integration structure. In order to solve the related problems that in an existing magnetic integration method, a magnetic core structure is complex in design and large in leakage magnetic flux, and an integration method lacks universality and the like, a single standard EE magnetic core is used for a common type converter with three magnetic element structures including a direct-current inductor, a leakage inductor and a transformer, the winding connection mode and the air gap parameters are reasonably designed, and the magnetic core structure is optimized. Compared with a discrete magnetic part, the number of magnetic elements of the converter can be reduced, the volume proportion of the magnetic part in the converter can be reduced, the volume of a converter system is further reduced, the power density is improved, the magnetic core design is simplified, and the manufacturing complexity of a magnetic integrated structure is reduced; unbalanced current of column windings on the two sides is suppressed, efficient and high-power-density operation of the system is achieved, and stability and reliability of operation of the system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a power electronic magnetic integration technology, in particular to a transformer magnetic integration structure and integration method of integrated double DC inductance and leakage inductance, and belongs to the field of high-frequency isolated switching power supply. BACKGROUND

[0002] In order to realize high-performance DC conversion in a wide voltage range, including soft switching, low current stress, current control performance and simple structure, etc., usually power electronic converters need multiple magnetic elements to store and release energy and shape the current waveform. However, multiple magnetic elements result in large magnetic component volume and large magnetic component loss, which in turn affects the power density and conversion efficiency of the converter, which is contrary to the current development direction of high frequency, high efficiency and high power density of power electronics. Through magnetic integration technology, multiple discrete magnetic components are wound on one magnetic core in terms of function and structure, which can effectively reduce the number of magnetic components, reduce the volume of the converter and reduce the loss of the magnetic components, which is of great significance to improve the power conversion efficiency and power density.

[0003] Currently, some magnetic integration structures and integration methods have been proposed by domestic and foreign researchers, but there are deficiencies in the simplification of magnetic core structure, uniform distribution of magnetic flux, etc., and the integration form is relatively single, and the integration method lacks universality. In 2022, Three Winding Coupled Inductor-Based Dual Active Bridge DC-DC Converter With Full Load Range ZVS Under Wide Voltage Range published in IEEE Transaction on industrial electronics proposed a dual active bridge dc-dc converter based on three winding coupled inductor, which integrated two equivalent dc inductors and a high frequency transformer into a three winding coupled inductor. Its advantages are the least number of magnetic cores and the maximum window utilization rate, and the disadvantage is that with the increase of the number of windings, the complexity of integrated structure design and production increases significantly. In 2022, An Interleaved Bidirectional Coupled-Inductor Based DC–DC Converter With High Conversion Ratio for Energy Storage System published in IEEE Transaction on industrial electronics proposed an interleaved bidirectional coupled-inductor based dc-dc converter, which integrated two dc inductors and a high frequency transformer by combining two coupled inductors. In order to further improve the power density, Dual Coupled Inductors with Controllable Integrated Leakage Inductance and CM Noise Suppression for CF-DAB Converter published in IEEE Transaction on power electronics in 2023 integrated leakage inductance in dual coupled inductor. As the power capacity of the unit transformer is reduced, the design of magnetic components is simplified. However, the number of magnetic cores increases, and the leakage flux increases due to the dependence of each unit transformer on the series connection of windings. It should be noted that large leakage inductance will affect the power transfer and soft switching performance of the converter. In fact, additional inductors are still needed in most current literature research to obtain the required leakage inductance to achieve the power transfer and soft switching requirements.

[0004] I. After searching, the Chinese invention patent with application number CN202210217679.4 discloses a kind of cascading topology magnetic integrated device, cascading topology magnetic integrated device includes magnetic core, transformer and inductance component, magnetic core includes multiple magnetic branches.The winding of transformer is wound on the magnetic branch.The winding of inductance component is wound on the magnetic branch.When inductance component and transformer are energized, the direct-current magnetic flux of inductance component is superimposed on the alternating-current magnetic flux formed by the winding of transformer in the magnetic branch, to improve the utilization rate of magnetic core.The technical problem of large size caused by too many magnetic cores in the power management circuit in the prior art is solved.

[0005] The technical comparison between the present application and the above-mentioned comparative document is as follows:

[0006] 1. The above-mentioned comparative document provides a kind of cascading topology magnetic integrated device, solves the technical problem of large size caused by too many magnetic cores in the power management circuit in the prior art, mainly faces a kind of cascading topology.

[0007] The present patent is to overcome the related problems in the existing magnetic integration method, such as complex magnetic core structure design, large leakage magnetic flux, and lack of universality of integration method, etc.The disclosed integrated transformer magnetic integration structure and integration method of double direct-current inductance and leakage inductance mainly face the dual active bridge dc-dc converter topology with double direct-current inductance, leakage inductance and transformer.

[0008] There are essential differences between the two in application scenarios and use backgrounds.

[0009] 2. The cascading topology magnetic integrated device proposed in the above-mentioned comparative document includes: a magnetic core, the magnetic core includes multiple magnetic branches; a transformer, the winding of the transformer is wound on the magnetic branch; an inductance component, the winding of the inductance component is wound on the magnetic branch; when the inductance component and the transformer are energized, the direct-current magnetic flux of the inductance component is superimposed on the alternating-current magnetic flux formed by the winding of the transformer in the magnetic branch, to improve the utilization rate of magnetic core.

[0010] The integrated transformer magnetic integration structure of double direct current inductance and leakage inductance includes an EE magnetic core, a primary winding Np1 and Np2, and a secondary winding Ns1 and Ns2. The three magnetic columns of the EE magnetic core each have an air gap. The primary winding Np1 is located on one side column of the EE magnetic core and forms a port 1. The primary winding Np2 is located on the other side column of the EE magnetic core and forms a port 2. The secondary windings Ns1 and Ns2 are respectively located on the two side columns of the EE magnetic core and are connected in series to form a port 3. Through the magnetic core structure and winding connection mode, the magnetic integration of the double direct current inductance and leakage inductance is realized. Compared with discrete magnetic components, the number of magnetic components of the transformer can be reduced, the volume proportion of the magnetic components in the transformer can be reduced, the volume of the transformer system can be reduced, the power density can be improved, the magnetic core design can be simplified, the manufacturing complexity of the magnetic integration structure can be reduced, the unbalanced current of the two side column windings can be suppressed, the system can be operated with high efficiency and high power density, and the stability and reliability of the system operation can be improved.

[0011] There are essential differences between the two in technical solutions, implementation paths, physical structures and beneficial effects.

[0012] II. According to the search, the Chinese invention patent with the application number CN201410332723.1 provides a single-stage boost inverter using a magnetic integrated transformer, which includes a direct current power supply (1), a single-stage boost network (2), and an inverter circuit (3). The direct current power supply (1) includes a power supply and an inductance L3. The single-stage boost inverter uses an integrated magnetic component (7) as a magnetic integrated transformer. The magnetic integrated magnetic component (7) includes oppositely arranged magnetic cores, which are respectively wound with a primary winding (n1) and a secondary winding (n2) and a winding (n3) of the inductance L3. The input end of the primary winding (n1) is connected to a primary circuit, and the output end of the secondary winding (n2) is connected to a secondary circuit. The winding (n3) of the inductance L3 is connected to the positive pole of the power supply, and the other end is connected to the single-stage boost network (2). The primary winding (n1) and the secondary winding (n2) are composed of a coupling inductance or a tapped inductance. There is an air gap between each magnetic column of the oppositely arranged magnetic cores. The inverter can not only reduce the volume of the magnetic component, but also make the leakage inductance easy to control and reduce the copper loss of the winding.

[0013] The technical comparison between the present application and the above-mentioned comparative document is as follows:

[0014] 1. The single-stage boost inverter using a magnetic integrated transformer proposed in the above-mentioned comparative document includes a direct current power supply, a single-stage boost network, and an inverter circuit, and mainly faces a single-stage boost inverter topology.

[0015] The patent is to overcome the problems of complex magnetic core structure design, large leakage flux and lack of universality of the existing magnetic integration method. The disclosed transformer magnetic integration structure and integration method of integrating double DC inductance and leakage inductance mainly face the dual active bridge DC-DC converter topology with double DC inductance, leakage inductance and transformer.

[0016] There are essential differences between the two in application scenarios and use backgrounds.

[0017] 2. In the above-mentioned comparative document, the single-stage boost inverter uses an integrated magnetic component as a magnetic integrated transformer. The magnetic integrated magnetic component includes oppositely arranged magnetic cores, on which the primary winding (n1) and the secondary winding (n2) and the winding (n3) of the inductor L3 are respectively wound. The input end of the primary winding (n1) is connected to the primary circuit, and the output end of the secondary winding (n2) is connected to the secondary circuit. The winding (n3) of the inductor L3 is connected to the positive pole of the power supply, and the other end is connected to the single-stage boost network (2). The primary winding (n1) and the secondary winding (n2) are composed of a coupling inductor or a tapped inductor. There is an air gap between each magnetic column of the oppositely arranged magnetic cores. This inverter can not only reduce the volume of the magnetic component, but also make the leakage inductance easy to control and reduce the copper loss of the winding.

[0018] The disclosed transformer magnetic integration structure of integrating double DC inductance and leakage inductance includes an EE magnetic core, primary windings Np1 and Np2, and secondary windings Ns1 and Ns2. The three magnetic columns of the EE magnetic core each have an air gap. The primary winding Np1 is located on one side column of the EE magnetic core and forms port 1, the primary winding Np2 is located on the other side column of the EE magnetic core and forms port 2, and the secondary windings Ns1 and Ns2 are respectively located on the two side columns of the EE magnetic core and are connected in series to form port 3. Through the magnetic core structure and winding connection mode, the magnetic integration of the double DC inductance and leakage inductance transformer is realized. Compared with discrete magnetic components, the number of magnetic elements of the transformer can be reduced, the volume proportion of the magnetic component in the transformer can be reduced, and the volume of the transformer system can be reduced, the power density can be improved, the magnetic core design can be simplified, the manufacturing complexity of the magnetic integration structure can be reduced, the unbalanced current of the two side column windings can be suppressed, the system can be operated efficiently and at high power density, and the stability and reliability of the system operation can be improved.

[0019] There are essential differences between the two in technical solutions, implementation paths, physical structures and beneficial effects. SUMMARY

[0020] This invention proposes a transformer magnetic integration structure and integration method that integrates dual DC inductors and leakage inductance. The technical problem to be solved is: for commonly used converters containing three types of magnetic components—DC inductor, leakage inductance, and transformer—this invention uses a single standard EE magnetic core and, through reasonable design of winding connection methods and air gap parameters, achieves the integration of dual DC inductors, leakage inductance, and transformer. Compared with discrete magnetic components, this invention can reduce the number of magnetic components in the converter, reduce the volume ratio of magnetic components in the converter, thereby reducing the size of the converter system, increasing power density, simplifying core design, reducing the complexity of magnetic integration structure fabrication, suppressing unbalanced current in the two-sided column windings, achieving efficient and high-power-density system operation, and improving the stability and reliability of system operation.

[0021] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0022] A transformer magnetic integrated structure integrating dual DC inductors and leakage inductance, characterized in that it includes an EE magnetic core and a primary winding N. p1 and N p2 Secondary winding N s1 and N s2 The EE magnetic core has three magnetic pillars: a first magnetic pillar, a second magnetic pillar, and a third magnetic pillar. The first and third magnetic pillars are located on opposite sides of the second magnetic pillar. The magnetic flux directions of the first and third magnetic pillars are the same but opposite to those of the second magnetic pillar. Air gaps are provided on the first, second, and third magnetic pillars. The primary winding N... p1 The primary winding N is located on the first magnetic post and forms port one thereon. p2 Located on the third magnetic post and forming port two thereon, the secondary winding N s1 and N s2 They are located on the first and third magnetic pillars respectively and form port three after being connected in series.

[0023] As a preferred technical solution of the present invention: the primary winding N p1 and N p2 Reused as dual DC inductor winding N L1 N L1 and transformer primary winding N p The secondary winding N s1 and N s2 For the secondary winding N of the transformer s The primary winding and the secondary winding satisfy formula (1):

[0024] (1).

[0025] As a preferred embodiment of the present invention: the current i flowing through the primary winding is a ib The double direct-current inductance current i L1 , L2 The primary winding current i of the superimposed transformer p , satisfies formula (2):

[0026] (2).

[0027] As a preferred technical solution of the application: the magnetic flux of the first magnetic column and the third magnetic column is respectively phi1 and phi2, and the magnetic flux of the second magnetic column is phi c , through the magnetic integrated transformer reluctance model, the magnetic flux relationship is solved, as shown in formula (3):

[0028] (3)

[0029] Wherein, R1 and R2 are the air gap reluctance of the first magnetic column and the third magnetic column respectively, and R c is the air gap reluctance of the second magnetic column,

[0030] According to Faraday's law of electromagnetic induction and formula (2), the inductance matrix is as shown in formula (4):

[0031] (4)

[0032] Wherein, L a and L b are the self-inductance of the primary winding N p1 and N p2 , M ab is the mutual inductance between the primary winding N p1 and N p2 , M ac and M bc are the mutual inductance between the primary winding N p1 and the secondary winding N s1 +N s2 , and the mutual inductance between the primary winding N p2 and the secondary winding N s1 +N s2 , L c is the self-inductance of the secondary winding N s1 +N s2 , therefore, the design of the magnetic integrated transformer can be regarded as the design of the multi-winding coupled inductance L,

[0033] The equivalent relationship between the multi-winding coupled inductance L and the required transformer parameters of the converter is as shown in formula (5):

[0034] (5)

[0035] Wherein, L m1 and L m2The equivalent excitation inductance of the winding, and the equivalent excitation inductance is used as a direct current inductance, N p :N s The equivalent transformer ratio, L r_ab Is the equivalent leakage inductance.

[0036] As a preferred technical solution of the application: the single EE magnetic core is a standard EE magnetic core.

[0037] As a preferred technical solution of the application: the air gaps on the first magnetic column, the second magnetic column and the third magnetic column are respectively located at the middle positions of the respective magnetic columns.

[0038] As a preferred technical solution of the application: it further comprises a first horizontal column and a second horizontal column, and the two ends of the first magnetic column, the second magnetic column and the third magnetic column are respectively fixed on the first horizontal column and the second horizontal column.

[0039] The application integrates the direct current inductance, the leakage inductance and the transformer into a single standard EE magnetic core through formula (5), and the magnetic integration structure integrates four magnetic elements, including double direct current inductance, leakage inductance and transformer. The double direct current inductance is connected in series and then connected in parallel with the primary winding of the transformer, and the secondary winding of the transformer is connected in series with the leakage inductance, thereby realizing the magnetic integration structure of the transformer integrating double direct current inductance and leakage inductance. The magnetic integration structure can reduce the number of magnetic elements in the converter, reduce the volume proportion of the magnetic element in the converter, and further reduce the volume of the converter system, reduce the loss of the magnetic element, and realize the high efficiency and high power density operation of the system. In addition, the direct current inductance, the leakage inductance and the transformer turn ratio are only related to the winding turns and the magnetic resistance. Therefore, by adjusting the winding turns and the air gap magnetic resistance of the single EE magnetic core, the inductance parameters and the transformer turn ratio can be flexibly controlled, the magnetic core design is simplified, and the manufacturing complexity of the magnetic integration structure is reduced. Finally, due to the existence of the column air gap in the transformer magnetic integration structure, the natural coupling relationship exists between the two side column windings N p1 And N p2 , and the two side column windings can effectively suppress the unbalanced current between the windings, and improve the stability and reliability of the system operation.

[0040] The transformer magnetic integration method integrating double direct current inductance and leakage inductance is characterized in that it comprises the following steps:

[0041] S1: determining the transformer parameters required for realizing the operation performance of the converter, including double direct current inductance L1 and L2, leakage inductance L r , transformer ratio N p :N s , and coupling coefficient K of the two side column windings;

[0042] S2: obtaining a multi-winding coupled inductance matrix L from the transformer parameters, calculating the winding turns N p1 , N p2, N s1 , N s2 and air gap reluctance R p , R c ;

[0043] S3: calculating the maximum magnetic flux of the transformer operation, according to formula (3), the magnetic flux waveform of the three magnetic columns of the magnetic integrated transformer can be obtained, and phi2-phi1 is the alternating current magnetic flux without direct current bias circulating in the two side columns;

[0044] S4: determining the cross-sectional area of the magnetic core according to the maximum magnetic flux, as shown in formula (6):

[0045] (6)

[0046] Wherein, B recommed According to the working frequency of the transformer, the magnetic core is selected,

[0047] S5: determining the air gap length of the transformer magnetic integrated structure, as shown in formula (7):

[0048] (7)

[0049] Wherein, mu0 is the magnetic permeability of vacuum, and thus the magnetic integrated transformer design based on a single EE magnetic core is completed.

[0050] According to the magnetic integrated transformer parameters of steps S1 to S5, the direct current inductance, leakage inductance and transformer are integrated into a single standard EE magnetic core, the magnetic integrated structure integrates four magnetic elements, including double direct current inductance, leakage inductance and transformer. The magnetic integrated structure of the transformer can reduce the number of magnetic elements of the transformer, reduce the volume proportion of the magnetic element in the transformer, and further reduce the volume of the transformer system, reduce the loss of the magnetic element, realize the high efficiency and high power density operation of the system. In addition, the turns ratio of the direct current inductance, the leakage inductance and the transformer is only related to the number of turns and the magnetic reluctance. Therefore, by adjusting the number of turns of the winding of the single EE magnetic core and the air gap reluctance, the inductance parameters and the transformer turns ratio can be flexibly controlled, the magnetic core design is simplified, and the manufacturing complexity of the magnetic integrated structure is reduced. Finally, due to the existence of the column air gap in the transformer magnetic integrated structure, the natural coupling relationship exists between the two side column windings N p1 and N p2 , the two side column windings can effectively suppress the unbalanced current between the windings, and improve the stability and reliability of the system operation.

[0051] Compared with the prior art, the beneficial effects of the present application are:

[0052] 1. The transformer magnetic integration structure and integration method disclosed in this invention integrates dual DC inductors and leakage inductors. For commonly used converters containing three types of magnetic components—DC inductors, leakage inductors, and transformers—this invention uses a single standard EE magnetic core and achieves the integration of dual DC inductors, leakage inductors, and transformers through reasonable design of winding connection methods and air gap parameters. This reduces the number of magnetic components in the converter, decreases the volume ratio of magnetic components in the converter, thereby reducing the size of the converter system, reducing magnetic component losses, and helping to improve system efficiency and power density.

[0053] 2. The integrated transformer magnetic structure and its integration method that integrates dual DC inductors and leakage inductance disclosed in this invention can achieve flexible control of inductance parameters and transformer turns ratio by adjusting the number of winding turns and air gap magnetic resistance of a single EE magnetic core, simplifying magnetic core design and reducing the complexity of manufacturing the magnetic integrated structure.

[0054] 3. The transformer magnetic integration structure and integration method disclosed in this invention, which integrates dual DC inductors and leakage inductance, has N-type column windings on both sides due to the presence of column air gaps in the transformer magnetic integration structure. p1 and N p2 There is a natural coupling relationship between them, and the column windings on both sides can effectively suppress the unbalanced current between the windings, thereby improving the stability and reliability of the system operation. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the EE core structure and winding connections;

[0056] Figure 2 This is a circuit diagram of the EE magnetic core structure;

[0057] Figure 3 This is a diagram of the magnetoresistive model in this application;

[0058] Figure 4 This is a three-dimensional structural diagram of the present invention;

[0059] Figure 5 This is a schematic diagram of the current-source dual active bridge converter in this embodiment;

[0060] Figure 6 A flowchart illustrating a transformer magnetic integration method that integrates dual DC inductors and leakage inductance. Detailed Implementation

[0061] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0062] like Figures 1-4 As shown, this invention proposes a transformer magnetic integrated structure that integrates dual DC inductors and leakage inductance, including an EE magnetic core and a primary winding N. p1 and N p2 Secondary winding Ns1 and N s2 , the EE magnetic core has three magnetic columns, respectively, a first magnetic column, a second magnetic column and a third magnetic column, the first magnetic column and the third magnetic column are respectively located on both sides of the second magnetic column, the magnetic flux directions of the first magnetic column and the third magnetic column are the same and the magnetic flux directions of the first magnetic column and the third magnetic column are opposite to the magnetic flux direction of the second magnetic column, the first magnetic column, the second magnetic column and the third magnetic column are respectively provided with air gaps, the primary winding N p1 is located on the first magnetic column and forms a port one thereon, the primary winding N p2 is located on the third magnetic column and forms a port two thereon, the secondary winding N s1 and N s2 are respectively located on the first magnetic column and the third magnetic column and form a port three after being connected in series.

[0063] The primary winding N p1 and N p2 are multiplexed as a double direct current inductance winding N L1 , N L1 and a transformer primary winding N p , the secondary winding N s1 and N s2 are transformer secondary windings N s , the primary winding and the secondary winding satisfy formula (1):

[0064] (1).

[0065] The current i a , i b flowing through the primary winding is a double direct current i L1 , i L2 superimposed transformer primary winding current i p , satisfying formula (2):

[0066] (2).

[0067] The magnetic fluxes of the first magnetic column and the third magnetic column are respectively phi1 and phi2, and the magnetic flux of the second magnetic column is phi c , the magnetic flux relationship is solved through a magnetic integrated transformer reluctance model, as shown in formula (3):

[0068] (3)

[0069] Wherein, R1 and R2 are the air gap reluctances of the first magnetic column and the third magnetic column respectively, R cThe air gap reluctance of the second magnetic column, because the permeability of the EE magnetic core is much greater than that of air, the magnetic core reluctance can be ignored, R1 and R2 are the air gap reluctances of the two side columns of the EE magnetic core, respectively, for the purpose of simplifying the design, the air gap reluctances of the two side columns are usually equal, that is, R1=R2=R p

[0070] According to Faraday's law of electromagnetic induction and formula (2), the inductance matrix is shown in formula (4):

[0071] (4)

[0072] Where, L a and L b are the self-inductances of the primary winding N p1 and N p2 , M ab is the mutual inductance between the primary winding N p1 and N p2 , M ac and M bc are the mutual inductances between the primary winding N p1 and the secondary winding N s1 +N s2 , and between the primary winding N p2 and the secondary winding N s1 +N s2 , L c is the self-inductance of the secondary winding N s1 +N s2 , therefore, the design of the magnetic integrated transformer can be regarded as the design of the multi-winding coupled inductance L,

[0073] The equivalent relationship between the multi-winding coupled inductance L and the required transformer parameters of the converter is shown in formula (5):

[0074] (5)

[0075] Where, L m1 and L m2 are the equivalent exciting inductances of the windings, and the equivalent exciting inductances are used as direct current inductances, N p :N s is the equivalent transformation ratio of the transformer, and L r_ab is the equivalent leakage inductance.

[0076] Wherein, the single EE magnetic core is a standard EE magnetic core. The air gaps on the first magnetic column, the second magnetic column and the third magnetic column are respectively located at the middle positions of the respective magnetic columns. Further comprising a first cross column and a second cross column, two ends of the first magnetic column, the second magnetic column and the third magnetic column are respectively fixed on the first cross column and the second cross column

[0077] Embodiment: Take a common type of current source type dual active bridge dc-dc converter as an example to illustrate the effectiveness and feasibility of the integrated dual DC inductor and leakage inductor transformer magnetic integrated structure and the design method thereof disclosed in the present application.

[0078] Figure 5 A magnetic integrated dual active bridge converter schematic diagram is provided for the embodiment, and the magnetic integrated dual active bridge converter provided by the embodiment includes a primary side full bridge, a secondary side full bridge, a magnetic integrated part, a primary side DC power supply, a secondary side DC power supply, an intermediate stage clamping capacitor and an output filter capacitor. 1a , Q 2a , Q1, Q2, points a and b are the midpoints of the two bridge arms of the primary side active bridge, and v ab is the potential difference between points a and b; the secondary side full bridge includes switching devices S1, S2, S3 and S4, points c and d are the midpoints of the two bridge arms of the primary side active bridge, and v cd is the potential difference between points c and d; i p and i s are the currents of the primary side and the secondary side of the transformer of the converter; the magnetic integrated part includes DC inductors L1 and L2, leakage inductor L r , and high-frequency transformer T r .

[0079] The positive pole of the primary side DC power supply is connected to point e through two DC inductors, and the negative pole of the primary side DC power supply is connected to the source electrode of switching device Q2 and one end of clamping capacitor C c . The drain electrode of switching tube Q1 is connected to the source electrode of switching tube Q 1a , and the source electrode is connected to the source electrode of switching tube Q2. The drain electrode of switching tube Q2 is connected to the source electrode of switching tube Q 2a , and is connected to DC inductor L2 at point b. The drain electrode of switching tube Q 1a is connected to the other end of clamping capacitor C c and the drain electrode of Q 2a , and is connected to DC inductor L1 at point a. DC inductor L1 is connected in series with DC inductor L2, and is connected in parallel with the primary winding of high-frequency transformer T r at points a and b. The secondary winding of high-frequency transformer T r is connected to leakage inductor L r . Leakage inductor L r is connected to the source electrode of switching tube S1 and the drain electrode of switching tube S3 at point c, and the secondary winding of high-frequency transformer T rThe secondary winding of the transistor is connected to the source of switching transistor S2 and the drain of switching transistor S4 at point d. The drain of switching transistor S1 is connected to the drain of switching transistor S2 and the positive terminal of output capacitor C, and is also connected to the positive terminal of the output voltage. The source of switching transistor S3 is connected to the source of switching transistor S4 and the negative terminal of output capacitor C, and is also connected to the negative terminal of the output voltage.

[0080] like Figure 6 As shown, the transformer magnetic integration method for integrating dual DC inductors and leakage inductance disclosed in this invention includes the following steps:

[0081] S1: Under the premise of achieving soft switching of all switching transistors and the current-source dual active bridge DC-DC converter operating at a relatively small effective current value, determine the required transformer parameters, including the dual DC inductors L1 and L2, and the leakage inductance L... r Transformer ratio N p :N s The coupling coefficient K of the two column windings;

[0082] S2: Obtain the multi-winding coupled inductance matrix L from the transformer parameters. Calculate the number of winding turns N of a single EE core according to formula (5). p1 N p2 N s1 N s2 and air gap magnetoresistance R p R c .

[0083] S3: Calculate the maximum magnetic flux of the converter. According to formula (3), the magnetic flux waveforms of the three magnetic columns of the magnetic integrated transformer can be obtained, and ϕ2–ϕ1 is the AC magnetic flux without DC bias flowing in the two columns.

[0084] S4: To prevent core saturation, determine the appropriate core cross-sectional area based on the maximum magnetic flux, as shown in formula (6):

[0085] (6)

[0086] Among them, B recommed Select based on the converter's operating frequency.

[0087] S5: Determine the air gap length of the transformer's magnetic integrated structure, as shown in formula (7):

[0088] (7)

[0089] Where μ0 is the permeability of free space. Thus, the design of a magnetically integrated transformer based on a single EE core is completed.

[0090] According to the magnetic integrated transformer parameters of steps S1 to S5, the direct current inductance, leakage inductance and transformer are integrated into a single standard EE magnetic core, the magnetic integrated structure integrates four magnetic elements including double direct current inductance, leakage inductance and transformer. The magnetic element quantity of the transformer can be reduced by the transformer magnetic integrated structure, the volume proportion of the magnetic element in the transformer is reduced, and then the volume of the transformer system is reduced, the magnetic element loss is reduced, and the system high efficiency and high power density operation are realized. In addition, the direct current inductance, leakage inductance and transformer turn ratio are only related to the winding turns and the magnetic resistance. Therefore, by adjusting the winding turns and the air gap magnetic resistance of the single EE magnetic core, the inductance parameters and the transformer turn ratio can be flexibly controlled, the magnetic core design is simplified, and the manufacturing complexity of the magnetic integrated structure is reduced. Finally, due to the existence of the column air gap in the transformer magnetic integrated structure, the coupling relationship naturally exists between the two side column windings N p1 and N p2 The two side column windings can effectively suppress the unbalanced current between the windings, and improve the stability and reliability of the system operation.

[0091] The primary side full bridge and the secondary side full bridge of the current source type dual active bridge dc-dc converter in the embodiment can adopt single phase shift control, extended phase shift control, etc. When the energy is forward transferred, the primary side full bridge works in the inverter state, and the secondary side full bridge works in the rectifier state. When the energy is reversely transferred, the secondary side full bridge works in the inverter state, and the primary side full bridge works in the rectifier state.

[0092] The primary side windings N p1 and N p2 respectively form the port 1 and the port 2 connected to the bridge arm midpoints a point and b point of the primary side full bridge, and the secondary side windings N s1 and N s2 in series form the port 3 connected to the bridge arm midpoints c point and d point of the secondary side full bridge. Under the magnetic integrated structure, the magnetic integrated transformer assists the transformer to realize the power transmission of the dual active bridge dc-dc converter through the connection of the primary and secondary direct current sources and the driving of the switching tubes.

[0093] It can be known from the above analysis that the transformer for realizing electrical isolation of the transformer can be optimized, the control freedom is increased, the two-way power transmission of the transformer under the soft switching in the full load range can be more flexibly assisted, the volume proportion and the loss of the magnetic elements of the transformer are reduced, the power density and the operation efficiency of the transformer are improved, the unbalanced current suppression effect on the two side column windings can be naturally realized, and the stability and the reliability of the transformer operation are improved.

[0094] It should be noted that the above specific description further details the purposes, technical solutions and beneficial effects of the application, the magnetic integrated structure is applied to the current source type dual active bridge converter, and is not used to limit the protection scope of the application in this topology, and any modification, equivalent replacement, improvement and the like made on the basis of the application should be included in the protection scope of the application. The magnetic integrated structure and the magnetic integrated transformer design method proposed in the application can be applied to the transformer containing a direct current inductor, a leakage inductor and a transformer, and can also be applied to the integration between coupled inductors and inductors, significantly improves the power density of the transformer, and realizes high-performance operation of the transformer.

Claims

1. A transformer magnetic integration structure integrating a dual DC inductance and leakage inductance, characterized in that: An EE magnetic core, a primary winding N p1 and N p2 , a secondary winding N s1 and N s2 , the EE magnetic core has three magnetic columns, respectively a first magnetic column, a second magnetic column and a third magnetic column, the first magnetic column and the third magnetic column are respectively located on both sides of the second magnetic column, the magnetic flux directions of the first magnetic column and the third magnetic column are the same and the magnetic flux directions of the first magnetic column and the third magnetic column are opposite to the magnetic flux direction of the second magnetic column, the first magnetic column, the second magnetic column and the third magnetic column are respectively provided with air gaps, the primary winding N p1 is located on the first magnetic column and forms a port one thereon, the primary winding N p2 is located on the third magnetic column and forms a port two thereon, the secondary winding N s1 and N s2 are respectively located on the first magnetic column and the third magnetic column and form a port three after being connected in series.

2. The integrated dual DC inductance and leakage inductance transformer magnetic integration structure of claim 1, wherein: The primary winding N p1 and N p2 multiplexed as a double direct-current inductor winding N L1 , N L1 and a transformer primary winding N p , the secondary winding N s1 and N s2 is a transformer secondary winding N s , and the primary winding and the secondary winding satisfy formula (1): (1)。 3. The integrated dual DC inductance and leakage inductance transformer magnetic integration structure of claim 1, wherein: the current i flowing through the primary winding a , i b is the double direct current inductance current i L1 , i L2 the primary winding current i of the superimposed transformer p , satisfies formula (2): (2)。 4. The integrated dual DC inductance and leakage inductance transformer magnetic integration structure of claim 1 or 3, wherein: The magnetic fluxes of the first magnetic column and the third magnetic column are ϕ1 and ϕ2 respectively, and the magnetic flux of the second magnetic column is ϕ c By solving the magnetic flux relationship formula through the magnetic integrated transformer magnetic resistance model, the formula (3) is shown: (3) wherein R1 and R2 are the air-gap reluctance of the first and third magnetic columns, respectively, R c is the air-gap reluctance of the second magnetic column, According to Faraday's law of electromagnetic induction and formula (2), the inductance matrix is shown as formula (4): (4) wherein L a and L b are the self-inductances of the primary winding N p1 and N p2 respectively, M ab is the mutual inductance between the primary winding N p1 and N p2 , M ac and M bc are the mutual inductances between the primary winding N p1 and the secondary winding N s1 +N s2 , and between the primary winding N p2 and the secondary winding N s1 +N s2 respectively, L c is the self-inductance of the secondary winding N s1 +N s2 , thus the design of the magnetic integrated transformer can be considered as the design of multi-winding coupled inductors L, The equivalent relationship between the multi-winding coupled inductance L and the required transformer parameters of the converter is shown as formula (5): (5) where L m1 and L m2 are the equivalent field inductances of the winding, respectively, and the equivalent field inductances are used as DC inductances, N p : N s is the equivalent transformation ratio of the transformer, and L r_ab is the equivalent leakage inductance.

5. The integrated dual DC inductance and leakage inductance transformer magnetic integration structure of claim 1, wherein: The single EE magnetic core is a standard EE magnetic core.

6. The integrated dual DC inductance and leakage inductance transformer magnetic integration structure of claim 1, wherein: The air gaps on the first magnetic column, the second magnetic column and the third magnetic column are respectively located at the middle positions of the first magnetic column, the second magnetic column and the third magnetic column.

7. The integrated transformer magnetic integration structure of dual DC inductance and leakage inductance according to claim 1, characterized in that: The first horizontal column and the second horizontal column are further included, and two ends of the first magnetic column, the second magnetic column and the third magnetic column are respectively fixed on the first horizontal column and the second horizontal column.

8. The integrated dual DC inductance and leakage inductance transformer magnetic integration method of any one of claims 1-7, wherein, The method comprises the following steps: S1: determining the transformer parameters required to achieve the converter operating performance, including the double DC inductances L1 and L2, the leakage inductance L r , the turns ratio N p : N s , the two-sided column winding coupling coefficient K; S2: obtain the multi-winding coupled inductance matrix L from the transformer parameters, and calculate the winding turns N of the single EE magnetic core according to formula (5) p1 p2 s1 s2 and air gap reluctance R p c ;​​​​ S3: calculating the maximum magnetic flux of the converter, according to formula (3), the magnetic flux waveform of the three magnetic columns of the magnetic integrated transformer can be obtained, and phi2-phi1 is the alternating current magnetic flux without direct current bias circulating in the two side columns; S4: determining the cross-sectional area of the magnetic core according to the maximum magnetic flux, as shown in formula (6): (6) wherein B recommed According to the operating frequency selection of the transformer, S5: determining the air gap length of the magnetic integrated structure of the transformer, as shown in formula (7): (7) Wherein, μ0 is the magnetic permeability of vacuum, thus, the magnetic integrated transformer design based on a single EE magnetic core is completed.

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