Multiphase magnetic integrated transformer

Abstract

The invention discloses a multi-phase magnetic integrated transformer which comprises multi-phase magnetic cores, and each phase of magnetic core is composed of a winding magnetic core and a non-winding magnetic core. The winding of each phase of magnetic core is wound on the winding magnetic core of the respective phase, and the winding of each phase of magnetic core is composed of a primary winding and a secondary winding; the leakage inductance of the multiphase magnetic integrated transformer is set according to the excitation inductance, the width of the air gap and the coupling coefficient of the primary winding and the secondary winding. Compared with the prior art, leakage inductance is set through the excitation inductor and the coupling coefficient, an inductance element is replaced, magnetic integration of the inductor and the transformer is achieved, meanwhile, the thin seams are formed so that magnetic flux generated by any phase of winding can flow through the non-winding magnetic cores of the other two phases, the sectional area of the non-winding magnetic cores can be reduced, and the magnetic integration of the inductor and the transformer can be achieved. By adjusting the winding mode of the winding, heat distribution of the winding is optimized, management is facilitated, and finally, the magnetic core is covered with the heat dissipation sheet, so that the magnetic core is prevented from being deformed and damaged in the violent high-low temperature change process.

Description

Technical Field

[0001] The invention relates to the field of transformer integration, in particular to a multi-phase magnetic integrated transformer. Background Art

[0002] For existing multi-phase isolated interleaved converters, in order to realize the soft switching operation of the switching device, an inductor is connected in series on both sides or one side of the transformer. In recent years, for single-phase isolated converters, some scholars have proposed that the transformer's own leakage inductance can be used to replace the inductor connected in series with the transformer. This type of transformer is usually called a magnetic integrated transformer. The leakage inductance of the transformer is mainly achieved by using the coupling relationship between the windings and the setting of the air gap to achieve precise control of the transformer leakage inductance.

[0003] Traditional multi-phase transformers are often composed of independent single-phase transformers. The leakage inductance of each transformer is composed of the air gap and winding coupling of each transformer itself. At the same time, the cross-sectional area of ​​the magnetic core must meet the maximum magnetic flux requirement to avoid the magnetic density in the magnetic core reaching the maximum limit. However, for multi-phase parallel converters, the magnetic flux inside each phase of the traditional independent transformer is not a fixed value, but will change with the change of the winding excitation current. Therefore, the cross-sectional area of ​​the magnetic core of each phase transformer is larger, and the overall transformer volume is larger.

[0004] For a multi-phase interleaved transformer, ideally, the currents in the multi-phase windings on the input side are symmetrical, that is, the sum of the excitation currents of the multi-phase windings is zero at any time, and the phase of the excitation current of each phase divides the entire switching cycle equally, and the excitation current amplitudes of each phase are consistent. Therefore, it is worth studying how to use the relationship between the excitation currents of the phases to optimize the core design and design it into a small-volume multi-phase transformer overall structure. Summary of the invention

[0005] In view of the problems in the prior art, the present invention proposes a multi-phase magnetic integrated transformer.

[0006] The technical solution of the present invention is to propose a multi-phase magnetic integrated transformer, including a multi-phase magnetic core, each phase magnetic core is composed of a wound magnetic core and a non-wound magnetic core;

[0007] The winding of each phase core is wound on the winding core of the respective phase, and the winding of each phase core is composed of a primary winding and a secondary winding;

[0008] The leakage inductance of the multi-phase magnetic integrated transformer is set according to the excitation inductance, the width of the air gap, and the coupling coefficient between the primary winding and the secondary winding.

[0009] Furthermore, the coupling coefficient is set according to the proportion of the high-coupling winding and the low-coupling winding in the primary winding and the secondary winding.

[0010] Furthermore, the primary winding and the secondary winding are both adjacent to or cover the air gap, and the air gap is provided at the junction of the wound magnetic core and the non-wound magnetic core.

[0011] Furthermore, the non-wound magnetic core of each phase is divided into two parts, and a fine gap is provided between the two parts.

[0012] Furthermore, the multi-phase magnetic integrated transformer is provided with fine gaps between the non-winding magnetic cores of adjacent phase transformers.

[0013] Furthermore, the multi-phase magnetic integrated transformer is provided with a three-phase winding, and the winding method of each phase winding is set according to the direction of the magnetic flux and satisfies: when the excitation current is positive, the direction of the magnetic flux in each phase magnetic core is consistent.

[0014] Furthermore, the positions of the primary winding and the secondary winding of the second phase winding in the three-phase winding are reversed with those of the primary winding and the secondary winding in the winding of the adjacent phase.

[0015] Furthermore, the outside of the magnetic core of the multi-phase magnetic integrated transformer is covered with a heat dissipation sheet.

[0016] Furthermore, the leakage inductance satisfies the calculation model:

[0017] L k =(1-coef 2 )L m

[0018] Among them, L k is the leakage inductance, coef is the coupling coefficient between the primary winding and the secondary winding, L m is the magnetizing inductance.

[0019] Furthermore, the excitation inductance satisfies the calculation model:

[0020]

[0021] Among them, L m is the excitation inductance, N is the number of turns of the multi-phase magnetic integrated transformer, μ 空 is the air magnetic permeability, Ae is the cross-sectional area of ​​the magnetic core, and gap is the width of the air gap.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] 1. The present invention utilizes the excitation inductance and the coupling coefficient of the primary winding and the secondary winding to configure the leakage inductance, replaces the inductance element with the leakage inductance, realizes the setting of the multi-phase magnetic integrated transformer, and at the same time, the position of the air gap is exquisite, which reasonably takes into account the heat dissipation of the winding and the shielding of the leakage magnetic field;

[0024] 2. In the present invention, each phase non-winding magnetic core is divided into two parts, and a fine gap is left between the two parts. The fine gap ensures that the magnetic core will not deform or crack, and at the same time, the magnetic flux generated by any phase winding can flow through the non-winding magnetic cores of the other two phases, thereby reducing the cross-sectional area of ​​the non-winding magnetic core itself. Similarly, when the magnetic flux of other phases is large, a similar effect will occur. Accordingly, the overall volume of the transformer is reduced;

[0025] 3. The present invention is applicable to multi-phase transformers, wherein the winding method criteria of the three-phase windings are given for the three-phase transformer: when the excitation current is positive, the direction of the magnetic flux in each phase magnetic core is consistent, thereby utilizing the relationship that the sum of the three-phase currents is zero, greatly reducing the cross-sectional area of ​​the non-wound magnetic core, and at the same time, the primary winding and the secondary winding of the second phase winding are reversed with the primary winding and the secondary winding of the winding of the adjacent phase, thereby optimizing the heat distribution of the transformer winding and facilitating heat management;

[0026] Other multi-phase transformers can also be set based on the above principle to reduce the cross-sectional area of ​​the non-wound core and optimize the heat distribution of the transformer windings;

[0027] 4. The present invention covers the outside of the magnetic core with a heat dissipation sheet. The high thermal conductivity of the heat dissipation sheet is beneficial to the heat dissipation of the magnetic core itself, preventing the magnetic core from being deformed and damaged during drastic temperature changes. The fine gaps in the magnetic core also have the function of preventing the magnetic core from being deformed and cracked. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] FIG. 1( a ) is a schematic diagram of the structure of a phase transformer in a multi-phase magnetic integrated transformer;

[0030] FIG1( b ) is a schematic diagram of the structure of the winding core and the non-winding core of a phase transformer in a multi-phase magnetic integrated transformer;

[0031] Figure 2(a) is a schematic diagram of the overall structure of a three-phase interleaved transformer;

[0032] FIG2( b ) is a schematic diagram of the magnetic core structure of FIG2( a );

[0033] Figure 3 Schematic diagram of magnetic resistance distribution in the magnetic core of a single-phase transformer corresponding to FIG1(b);

[0034] Figure 4(a) is the equivalent magnetic circuit diagram of the three-phase interleaved transformer;

[0035] Figure 4(b) shows the magnetic resistance R of the three-phase interleaved transformer without winding core m2 Equivalent magnetic circuit diagram after

[0036] FIG5( a ) is a schematic diagram showing the magnetic field and magnetic lines of force distribution generated when the current directions of adjacent solenoid windings are consistent;

[0037] FIG5( b ) is a schematic diagram of the magnetic field and magnetic lines of force distribution generated when the currents of adjacent solenoid windings are in opposite directions;

[0038] Figure 6 It is a schematic diagram of magnetic field distribution of a three-phase interleaved transformer when the winding current I1 on the first phase transformer, the winding current I2 on the second phase transformer, and the winding current I3 on ​​the third phase transformer satisfy I1=-I2-I3, I2=I3;

[0039] Figure 7 It is a schematic diagram of magnetic field distribution of a three-phase interleaved transformer when the winding current I1 on the first phase transformer, the winding current I2 on the second phase transformer, and the winding current I3 on ​​the third phase transformer satisfy I2=-I1-I3, I1=I3; DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0042] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0043] For single-phase isolated converters, some scholars have proposed that the transformer leakage inductance can be used to replace the inductor element connected in series with the transformer. This type of transformer is usually called a magnetic integrated transformer. The leakage inductance of the transformer is mainly achieved by using the coupling relationship between the windings and the setting of the air gap to achieve precise control of the transformer leakage inductance.

[0044] For the existing multi-phase isolated interleaved converter, in order to realize the soft switching operation of the switching device, an inductor element is connected in series on both sides or one side of the transformer.

[0045] In order to save the design of inductance elements, the present invention sets the leakage inductance according to the excitation inductance and the coupling coefficient between the primary winding and the secondary winding, thereby realizing the setting of a multi-phase magnetic integrated transformer.

[0046] Specifically, the multi-phase magnetic integrated transformer proposed in the present invention comprises a multi-phase magnetic core, each phase magnetic core is composed of a wound magnetic core and a non-wound magnetic core;

[0047] The winding of each phase core is wound on the winding core of the respective phase, and the winding of each phase core is composed of a primary winding and a secondary winding;

[0048] The leakage inductance of the multi-phase magnetic integrated transformer is set according to the excitation inductance, the width of the air gap, and the coupling coefficient between the primary winding and the secondary winding.

[0049] The principle of the above leakage inductance setting is explained below:

[0050] Please refer to Figure 1(a) and Figure 1(b). For the magnetic integrated transformer, adding an air gap in the magnetic integrated transformer can simultaneously adjust the excitation inductance L of the magnetic integrated transformer. m and leakage inductance L k ;

[0051] Assume that the maximum transformer winding voltage amplitude is V max , the transformer winding voltage frequency is minimum f smin , then the number of transformer turns is:

[0052]

[0053] In the formula, B max is the maximum magnetic induction intensity, which is determined by the type of core material, and Ae is the core cross-sectional area.

[0054] The total reluctance is:

[0055]

[0056] Where, L m is the magnetizing inductance, which is derived from the operating characteristics of the topology.

[0057] Since the magnetic permeability of the core magnetic material is much greater than the magnetic permeability of air, the magnetic resistance of the ferrite is ignored, and the magnetic resistance is mainly provided by the air gap. The required air gap width gap is:

[0058] gap=R m μ 空 Ae

[0059] In the formula, μ 空 is the magnetic permeability of air.

[0060] Combining the above formulas, we can see that the excitation inductance can be determined by the width of the air gap and the cross-sectional area of ​​the core, and the expression is:

[0061]

[0062] The formula for calculating leakage inductance is:

[0063] L k =(1-coef 2 )L m

[0064] Where coef is the coupling coefficient between the primary winding and the secondary winding.

[0065] From the above formula, we can know that leakage inductance is related to excitation inductance and coupling coefficient. When the excitation inductance is constant, the larger the air gap, the lower the coupling coefficient between the primary winding and the secondary winding, the larger the leakage flux, and the larger the leakage inductance.

[0066] When the coupling coefficient is constant, the larger the air gap, the lower the excitation inductance and the smaller the leakage inductance.

[0067] Based on the above principle, the setting principle of the air gap in the present invention is:

[0068] Please refer to Figure 1(b). The air gap is set at the junction of the wound magnetic core and the non-wound magnetic core. The magnetic induction intensity in the space around the air gap is relatively high. If the winding is close to or covered at the air gap, that is, "the primary winding and the secondary winding are close to or covered at the air gap" as mentioned above, the metal material of the winding will produce obvious eddy current loss in the magnetic field, and this part of the winding will heat up seriously. However, there is an advantage. Since the magnetic permeability of metal is greater than that of air, most of the magnetic lines of force in the space around the air gap are confined in the winding and then enter the next magnetic column. The magnetic induction intensity outside the winding is greatly reduced.

[0069] The setting principle of high coupling winding and low coupling winding is:

[0070] The coupling coefficient is not only related to the air gap, but also to the winding method of the primary winding and the secondary winding. Both the primary winding and the secondary winding are divided into high-coupling windings (windings with high coupling coefficients) and low-coupling windings (windings with low coupling coefficients). High-coupling windings refer to the stacked winding parts of the primary winding and the secondary winding, and low-coupling windings refer to the stacked parts of the primary winding or the secondary winding itself.

[0071] Therefore, in the present invention, after the number of turns of the primary winding and the secondary winding is determined, the overall coupling coefficient of the primary winding and the secondary winding can be controlled by allocating the proportion of the high-coupling winding and the low-coupling winding, that is, "the coupling coefficient is set according to the proportion of the high-coupling winding and the low-coupling winding in the primary winding and the secondary winding" as mentioned above. In view of the influence of the winding conditions of the primary winding and the secondary winding on the leakage inductance, when the primary winding and the secondary winding are completely overlapped, the coupling coefficient of the two will reach the maximum and the leakage inductance will be the lowest;

[0072] When the primary winding and the secondary winding are not overlapped, the coupling coefficient between the two will be minimum and the leakage inductance will be maximum.

[0073] Please refer to FIG. 2( a ) and FIG. 2( b ) to explain the winding method of the three-phase winding and the principle of setting the slits in the present invention.

[0074] The present invention takes the transformer design of a three-phase interleaved converter as an example to elaborate on the optimization method of a multi-phase magnetic integrated transformer. The multi-phase magnetic integrated transformer proposed in the present invention includes a three-phase magnetic core, a three-phase winding, and a heat sink;

[0075] The difference between the present invention and the traditional three-phase independent transformer is that: the winding requirements of the three-phase windings - when the excitation currents of the three-phase transformers are all positive, it is necessary to ensure that the generated magnetic flux is in the same direction, that is, the "multi-phase magnetic integrated transformer is provided with three-phase windings, and the winding method of each phase winding is set according to the direction of the magnetic flux, and it satisfies: when the excitation current is positive, the direction of the magnetic flux in each phase magnetic core is consistent";

[0076] In order to ensure the reliability of the transformer and prevent deformation and cracking during operation, fine gaps are usually set in the magnetic core. The setting of the fine gaps is not unique. The design principle in the present invention is: a fine gap should be set in the non-winding magnetic core of each phase, that is, "each phase non-winding magnetic core is divided into two parts, and a fine gap is set between the two parts" as mentioned above, so as to achieve the sharing of magnetic flux between phases while preventing the magnetic core from cracking.

[0077] In a preferred embodiment of the present invention, the fine gap is also provided between adjacent phase transformers, that is, as mentioned above, "the multi-phase magnetic integrated transformer has a three-phase transformer, and a fine gap is provided between the non-wound magnetic cores of adjacent phase transformers". In the present invention, the fine gap is substantially an extremely narrow air gap.

[0078] The relevant theoretical derivation and beneficial effect description are given below:

[0079] Common expressions in magnetic circuits are:

[0080] NI=HL

[0081] B=Hμ

[0082] φ=BS

[0083] In the above formula, N is the turns ratio, I is the excitation current of the transformer, H is the magnetic field strength, L is the magnetic path length, μ is the magnetic permeability, B is the magnetic induction intensity, S is the cross-sectional area of ​​the core, and Φ is the magnetic flux flowing through the cross section of the core.

[0084] Combining the above formulas, we can get:

[0085]

[0086] For multi-phase interleaved converters, in order to ensure the consistency of magnetic circuit parameters, the magnetic core of each phase transformer can be considered to be similar in shape and consistent in material, that is, the magnetic path length, magnetic permeability, and core cross-sectional area can be considered to be consistent. Therefore, the magnetic resistance of each part of the three-phase magnetic integrated transformer is correspondingly equal.

[0087] Define the magnetic resistance of the air gap as R m1 , the magnetic resistance of the slit is R m2 , the magnetic resistance of the magnetic core between the slits is R m3 , then these magnetic resistances can be determined as R m1 >>R m2 , R m1 >>R m3 .

[0088] There is a formula in the magnetic circuit:

[0089] φR m =NI

[0090] NI is the magnetic excitation source.

[0091] See also Figure 3 For a three-phase interleaved transformer, its magnetic circuit expression can be equivalent to Figure 4(a). m1 >>R m2 , connect the magnetic resistance R in series with the excitation source m2 omit, Figure 3 It can be further equivalent to Figure 4(b).

[0092] From the superposition theorem of magnetic circuit, we know that:

[0093]

[0094] In the above formula, R m′ =2R m3 +R m2 ; “ / / ” indicates a parallel relationship, that is, A / / B=A*B / (A+B), A / / B / / C=A / / (B / / C). If A>>B, then A / / B=B can be directly considered.

[0095] According to the formula in the magnetic circuit in the previous article:

[0096]

[0097] In the formula, μ r is the relative magnetic permeability of the magnetic material, μ0 is the magnetic permeability of vacuum (constant value).

[0098] In terms of order of magnitude, since the slit is actually an air gap, the magnetic permeability of the non-wound core between the slits is a thousand times different, and the length L is one thousandth of the core. Therefore, the magnetic resistance R of the two is m2 , R m3 It can be considered to be within an order of magnitude. To facilitate the description of the effect of the slit and winding setting on the magnetic flux in the non-wound core, assume that R m3 =R m2 .

[0099] The above formula can be simplified to:

[0100]

[0101] From the above formula, we can know that the magnetic flux in the shared core is not only related to the magnetic excitation of the current transformer but also to the other two-phase transformers. In addition, under ideal conditions, there is a relationship between the currents of multi-phase interleaved transformers: ∑I = 0, that is, the sum of all currents at any time is zero.

[0102] For example, when I1=-I2-I3, I2=I3, Obviously, compared with the non-wound core flux of the traditional independent three-phase transformer: The magnetic flux of the non-winding magnetic core of the three-phase interleaved transformer in the present invention is significantly reduced.

[0103] Based on the above principles, the present invention has the following beneficial effects:

[0104] The three-phase winding method adopted by the present invention utilizes the relationship that the sum of the excitation currents of the three-phase interleaved transformer is zero, so that the magnetic fluxes of the three-phase transformer cancel each other out in the non-wound magnetic core, greatly reducing the magnetic flux in the non-wound magnetic core of each phase, reducing the cross-sectional area of ​​the non-wound magnetic core, and greatly reducing the volume of the three-phase transformer;

[0105] Due to the setting of the fine gap, the magnetic flux of a certain phase transformer can flow through the non-winding magnetic core of each phase transformer, that is, the non-winding magnetic core of each phase transformer serves as a common path for the magnetic flux of the three-phase transformer, so that the maximum magnetic flux in a single non-winding magnetic core is reduced. The cross-sectional area of ​​the non-winding magnetic core is limited by the maximum magnetic induction intensity flowing through the magnetic core. The method of the present invention reduces the magnetic flux of each non-winding magnetic core. It can be seen from the commonly used expression in the magnetic circuit that the magnetic induction intensity of the non-winding magnetic core is reduced, and accordingly, the cross-sectional area of ​​the non-winding magnetic core can be reduced.

[0106] It should be noted that the above three-phase interleaved converter is only one embodiment of the present invention, and the design scheme proposed by the present invention is not only applicable to three-phase interleaved converters. For other multi-phase magnetic integrated transformers, based on the above ideas, the above beneficial effects can also be achieved.

[0107] Due to R m1 >>R m2 , R m1 >>R m3 , then the magnetic flux Φ1, Φ2, Φ3 in the wound core is almost unaffected by the length of the non-wound core, nor by the presence of the slit, that is:

[0108]

[0109] In the existing design, the magnetic flux inside the winding core is only related to the transformer excitation current and the turns ratio of the current phase. Compared with the traditional scheme, the magnetic loss is reduced, and the maximum value can be calculated, which is convenient for the design of the winding core.

[0110] The above content has demonstrated the role of the fine gap and the requirements for the winding method of the winding.

[0111] The winding method requirements give the purpose of winding. There are many specific winding methods. There is also a better winding method: the positions of the primary winding and secondary winding of the second phase transformer are different from those of the adjacent phase transformer, and their positions are reversed. That is, as mentioned above, "the positions of the primary winding and secondary winding of the second phase winding in the three-phase winding are reversed from the primary winding and secondary winding of the adjacent phase winding."

[0112] The advantage of this method is to ensure uniform temperature distribution between the phase windings of the magnetic integrated transformer. The specific principle is as follows:

[0113] Figures 5(a) and 5(b) show the magnetic field and magnetic force lines generated by adjacent solenoids. It can be seen from Figures 5(a) and 5(b) that when the current directions of adjacent windings are consistent, the directions of the magnetic force lines generated by the two windings in the space between the windings are also consistent, and the magnetic field is strengthened.

[0114] When the currents in adjacent windings are in opposite directions, the directions of the magnetic lines of force generated by the two windings in the space between the windings are also opposite, and the magnetic field is weakened;

[0115] This conclusion will be used to analyze the heating condition of the winding of the transformer proposed by the present invention:

[0116] The temperature of the winding comes from the heat transfer of the winding core and its own heating, and the self-heating depends on the resistance of the winding and the eddy current loss caused by the magnetic field. Among them, the heat transfer of the winding core and the resistance of the winding are relatively fixed and are affected by the working conditions and the winding material itself. Therefore, the eddy current loss is mainly compared here. When the electrical parameters are fixed, the eddy current loss is positively correlated with the magnetic field strength of the winding.

[0117] When I1=-I2-I3, I2=I3, assuming the transformer current is Figure 6 As shown, at this time, the middle part of the magnetic field between the first phase winding and the second phase winding is weakened, and the two end parts are strengthened; the middle part of the magnetic field between the second phase winding and the third phase winding is strengthened, and the two end parts are weakened. Therefore, the eddy current loss in the middle part of the first phase winding is small, and the two end parts are large; the eddy current loss in the middle and two end parts of the second phase winding is large on one side and small on the other side; the eddy current part of the middle part of the third phase winding is large, and the eddy current loss of the two end parts is small; it can be seen that the heat distribution is relatively dispersed, and the heat dissipation materials in the space can share the heat dissipation, the heat dissipation effect is good, and it is convenient for thermal design management.

[0118] If the winding method of the second phase is consistent with that of the adjacent phase, the magnetic field in the space between the second phase and the third phase is all in an enhanced state, the magnetic loss is large, the temperature in the space is high, the heat is relatively concentrated, the heat dissipation materials in the space cannot share the heat dissipation, the heat dissipation effect is poor, and thermal design management is inconvenient.

[0119] When I2=-I1-I3, I1=I3, assuming the transformer current is Figure 7 As shown in the figure, at this time, the middle part of the magnetic field between the first phase winding and the second phase winding is weakened, and the two end parts are strengthened; the middle part of the magnetic field between the second phase winding and the third phase winding is weakened, and the two end parts are strengthened. Therefore, the eddy current loss in the middle part of the three-phase winding is small, and the two end parts are large. It can be seen that the heat distribution is relatively dispersed, and the heat dissipation materials in the space can share the heat dissipation, the heat dissipation effect is good, and it is convenient for thermal design management.

[0120] If the winding method of the second phase is consistent with that of the adjacent phase, the magnetic field in the space between the adjacent phases is all in a weakened state, the magnetic loss is small, and the temperature in the space is low, which is more ideal.

[0121] However, thermal management mainly considers the worst heat distribution. Therefore, in general, it is better to use the proposed second phase winding method different from the adjacent phase in the project. That is, in the above setting, the primary winding and secondary winding of the second phase winding in the three-phase winding are reversed with the primary winding and secondary winding in the adjacent winding.

[0122] If the transformer itself has good heat dissipation conditions, both of the above-mentioned winding methods can be used.

[0123] Furthermore, the present invention covers the outside of the magnetic core with a heat dissipation sheet. The high thermal conductivity of the heat dissipation sheet is beneficial to the heat dissipation of the magnetic core itself, preventing the magnetic core from being deformed and damaged during drastic temperature changes. The fine gaps in the magnetic core also have the function of preventing the magnetic core from deforming and cracking.

[0124] It should be noted that the transformer optimization method proposed in the present invention is applicable to the transformer design of any phase interleaved converter.

[0125] Compared with the prior art, the present invention has at least the following beneficial effects:

[0126] 1. The present invention utilizes the excitation inductance and the coupling coefficient of the primary winding and the secondary winding to configure the leakage inductance, replaces the inductance element with the leakage inductance, realizes the setting of the multi-phase magnetic integrated transformer, and at the same time, the position of the air gap is exquisite, which reasonably takes into account the heat dissipation of the winding and the shielding of the leakage magnetic field;

[0127] 2. In the present invention, each phase non-winding magnetic core is divided into two parts, and a fine gap is left between the two parts. The fine gap ensures that the magnetic core will not deform or crack, and at the same time, the magnetic flux generated by any phase winding can flow through the non-winding magnetic cores of the other two phases, thereby reducing the cross-sectional area of ​​the non-winding magnetic core itself. Similarly, when the magnetic flux of other phases is large, a similar effect will occur. Accordingly, the overall volume of the transformer is reduced;

[0128] 3. The present invention is applicable to multi-phase transformers, wherein the winding method criteria of the three-phase windings are given for the three-phase transformer: when the excitation current is positive, the direction of the magnetic flux in each phase magnetic core is consistent, thereby utilizing the relationship that the sum of the three-phase currents is zero, greatly reducing the cross-sectional area of ​​the non-wound magnetic core, and at the same time, the winding method of the second phase winding is different from the winding method of the adjacent phase winding, thereby optimizing the thermal distribution of the transformer winding and facilitating thermal management;

[0129] Other multi-phase transformers can also be set based on the above principle to reduce the cross-sectional area of ​​the non-wound core and optimize the heat distribution of the transformer windings;

[0130] 4. The present invention covers the outside of the magnetic core with a heat dissipation sheet. The high thermal conductivity of the heat dissipation sheet is beneficial to the heat dissipation of the magnetic core itself, preventing the magnetic core from being deformed and damaged during drastic temperature changes. The fine gaps in the magnetic core also have the function of preventing the magnetic core from being deformed and cracked.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multiphase magnetic integrated transformer, characterized in that: It includes a multi-phase magnetic core, each phase magnetic core is composed of a wound magnetic core and a non-wound magnetic core; The winding of each phase core is wound on the winding core of the respective phase, and the winding of each phase core is composed of a primary winding and a secondary winding; The leakage inductance of the multi-phase magnetic integrated transformer is set according to the excitation inductance, the width of the air gap, and the coupling coefficient between the primary winding and the secondary winding.

2. The multiphase magnetic integrated transformer according to claim 1, characterized in that: The coupling coefficient is set according to the proportion of the high coupling winding and the low coupling winding in the primary winding and the secondary winding.

3. The multi-phase magnetic integrated transformer according to claim 1, characterized in that: The primary winding and the secondary winding are both adjacent to or cover the air gap, and the air gap is arranged at the junction of the wound magnetic core and the non-wound magnetic core.

4. The multi-phase magnetic integrated transformer according to claim 1, characterized in that: The non-wound magnetic core of each phase is divided into two parts, and a fine gap is arranged between the two parts.

5. The multi-phase magnetic integrated transformer according to claim 4, characterized in that: The multi-phase magnetic integrated transformer is provided with fine gaps between the non-winding magnetic cores of adjacent phase transformers.

6. The multi-phase magnetic integrated transformer according to claim 1, characterized in that: The multi-phase magnetic integrated transformer is provided with a three-phase winding, and the winding mode of each phase winding is set according to the direction of the magnetic flux and satisfies: when the excitation current is positive, the direction of the magnetic flux in each phase magnetic core is consistent.

7. The multi-phase magnetic integrated transformer according to claim 6, characterized in that: The positions of the primary winding and the secondary winding of the second phase winding in the three-phase winding are reversed with those of the primary winding and the secondary winding in the winding of the adjacent phase.

8. The multi-phase magnetic integrated transformer according to claim 1, characterized in that: The outside of the magnetic core of the multi-phase magnetic integrated transformer is covered with a heat dissipation sheet.

9. The multi-phase magnetic integrated transformer according to claim 1, characterized in that: The leakage inductance satisfies the calculation model: L k =(1-coef 2 )L m Among them, L k is the leakage inductance, coef is the coupling coefficient between the primary winding and the secondary winding, L m is the magnetizing inductance.

10. The multi-phase magnetic integrated transformer according to claim 9, characterized in that: The excitation inductance satisfies the calculation model: Among them, L m is the excitation inductance, N is the number of turns of the multi-phase magnetic integrated transformer, μ 空 is the air magnetic permeability, Ae is the cross-sectional area of ​​the magnetic core, and gap is the width of the air gap.

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