Magnetic integrated transformer capable of adjusting leakage inductance, three-port converter and vehicle-mounted charger

Abstract

The invention discloses a magnetic integrated transformer capable of adjusting leakage inductance, a three-port converter and a vehicle-mounted charger, the magnetic integrated transformer capable of adjusting leakage inductance comprises a main magnetic core, a first winding, a second winding and a third winding, the first winding comprises a first part and a second part which are wound on the two sides of the main magnetic core; the second winding is wound in the middle of the main magnetic core, and the third winding and the second winding are wound in a lap mode; each of the first winding and the second winding comprises an external winding section, an internal winding section and a crossed winding section, the external winding section is wound between the main magnetic core and the third winding, the internal winding section is wound inside the main magnetic core, and the crossed winding section is connected with the external winding section and the internal winding section; a magnetic shunt is arranged between the first winding and the second winding to form a magnetic flux path. Compared with the prior art, under the condition that the circuit performance is not sacrificed, the size of the vehicle-mounted charging system can be reduced, and the high-voltage battery and the low-voltage battery can be charged at the same time without additional assemblies.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to an adjustable leakage inductance magnetic integrated transformer, a three-port converter, and an on-board charger. Background Technology

[0002] With the rapid development of the electric vehicle industry, automakers need high-power vehicle charging systems (VCS) that can effectively reduce costs, size, and weight to improve product competitiveness. High-efficiency, high-power-density VCSs are crucial for electric vehicles. Furthermore, in addition to conventional grid-to-vehicle (G2V) charging, VCSs need to meet multi-functional charging requirements such as vehicle-to-grid (V2G), vehicle-to-load (V2L), low-voltage DC-DC converter (LDC), and simultaneous charging (SC). Traditional VCSs only meet unidirectional grid-to-vehicle (G2V) charging needs, with their on-board charger (OBC) and low-voltage DC-DC converter (LDC) being independent converters. This results in high cost, weight, size, and losses for VCSs, ultimately compromising the driving range and charging time of electric vehicles.

[0003] Magnetic components are key components affecting the power density of VCS. In recent years, literature has studied the integration of OBC and low-voltage DC-DC converters to improve the power density of OBC. By reconfiguring the topology of VCS through multi-winding transformers, OBC and LDC can share active switches and transformers at the same time. This not only reduces the number of semiconductor devices and transformers, but also allows heat sinks, sensing circuits and high-power cables to be shared between HVB and LVB, thereby reducing the size and cost of VCS.

[0004] Due to the application requirements of OBC, when the LDC output power is large, it has the characteristics of low voltage and high current. Copper busbar windings are required to ensure current density. In the three-port converter topology, the power inductance of OBC is integrated into the transformer in the form of leakage inductance, which can further improve the power density of OBC. However, the leakage flux generated by the leakage inductance induces eddy currents in the low voltage winding and the casing, resulting in a decrease in OBC efficiency. Secondly, when the leakage inductance of the transformer is large, it is difficult to integrate the power inductance of OBC. When the leakage inductance of the transformer is small, it will make soft switching of OBC difficult, resulting in low OBC efficiency.

[0005] Therefore, how to design an adjustable leakage inductance magnetic integrated transformer that can reduce the size of the on-board charging system without sacrificing circuit performance, while meeting the multi-functional charging needs of the on-board charger, is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention proposes a magnetically integrated transformer with adjustable leakage inductance, comprising a main magnetic core, a first winding, a second winding, and a third winding wound on the main magnetic core, wherein the first winding comprises a first part and a second part, and the first part and the second part are wound on both sides of the main magnetic core.

[0007] The second winding is wound in the middle of the main magnetic core, and the third winding is overlapped with the second winding;

[0008] The first winding and the second winding include an outer winding segment, an inner winding segment, and a cross winding segment. The outer winding segment is wound between the main magnetic core and the third winding. The inner winding segment is wound inside the main magnetic core. The cross winding segment connects the outer winding segment and the inner winding segment.

[0009] The main magnetic core is equipped with a magnetic shunt, which is located between the first winding and the second winding to form a magnetic flux path.

[0010] Furthermore, an air gap is provided between the magnetic shunt and the main magnetic core. The air gap is located between one end of the magnetic shunt and the main magnetic core, or the air gap is located inside the magnetic shunt, or multiple air gaps are provided in the magnetic shunt.

[0011] Furthermore, the leakage inductance is adjusted according to the size parameters of the main magnetic core, the size parameters of the magnetic shunt, and the distance between the first winding and the second winding.

[0012] Furthermore, the equivalent leakage inductance of the internal region of the main magnetic core satisfies:

[0013]

[0014] Where μ0 is the magnetic permeability in air, h a Let w be the window height of the main magnetic core, and l be the width of the main magnetic core. a l is the horizontal window length of the first part and the second part. b I is the horizontal window length of the second winding. p N is the current on the first winding. p H represents the number of turns in the first winding. y V is the magnetic field strength along the length of the main magnetic core. ew Let be the window volume of the main magnetic core.

[0015] Furthermore, the equivalent inductance and magnetizing inductance of the magnetic integrated transformer satisfy the following:

[0016]

[0017] Among them, L p L is the equivalent leakage inductance on the first winding side. s L is the equivalent leakage inductance on the second winding side. t L is the equivalent leakage inductance on the third winding side. m Let M be the magnetizing inductance of the integrated magnetic transformer, A and B be the equivalent turns ratio, and M be the magnetizing inductance. 12 M represents the mutual inductance between the first winding and the second winding. 13 M is the mutual inductance between the first winding and the third winding. 23 This refers to the mutual inductance between the second winding and the third winding.

[0018] Furthermore, the third winding is made of copper busbars or foil sheets, and the first winding and the second winding are fixed by a frame.

[0019] Furthermore, at the cross-wound segment, the winding sequence from top to bottom is the third winding, the second winding, and the first winding.

[0020] Furthermore, the first winding of the magnetic integrated transformer is connected to the primary-side conversion circuit of the on-board charger, the second winding of the magnetic integrated transformer is connected to the secondary-side conversion circuit of the on-board charger, the third winding of the magnetic integrated transformer is connected to the low-voltage DC conversion circuit of the on-board charger, and the leakage inductance of the magnetic integrated transformer serves as the power inductance of the on-board charger.

[0021] The present invention also proposes a three-port converter having the above-mentioned magnetically integrated transformer with adjustable leakage inductance.

[0022] The present invention also proposes an on-board charger having the above-mentioned three-port converter.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] 1. In this invention, the first winding and the second winding are alternately wound at the window of the main magnetic core, so that the external magnetic field strength can be canceled, thereby reducing the leakage magnetic field strength in the copper busbar area and reducing the eddy current loss of the copper busbar.

[0025] 2. In this invention, the first winding and the second winding are wound in a non-interleaved manner inside the main magnetic core window to form an effective number of turns, which can increase the leakage inductance. At the same time, a magnetic shunt is used to effectively reduce the winding distance between the first winding and the second winding without reducing the leakage inductance, so that the magnetic core size is smaller.

[0026] 3. The present invention divides the first winding into a first part and a second part, and the winding structure wound with the second winding can reduce the length of the cross winding section, making the structure of the magnetic integrated transformer more symmetrical, which is beneficial to ensuring the high coupling coefficient between the second winding and the third winding.

[0027] 4. The third winding uses copper busbars to fully wrap the leakage magnetic area of ​​the main magnetic core, which can achieve a magnetic shielding effect, further reduce the eddy current loss of leakage magnetic field to the internal casing of the on-board charger, and is beneficial to EMC design. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the magnetic integrated transformer of the present invention;

[0030] Figure 2 This is a schematic diagram showing the structure and dimensions of the main magnetic core of the present invention;

[0031] Figure 3 This is a schematic diagram of the magnetic flux path of the main magnetic core of the present invention in the ZY section;

[0032] Figure 4 This is a schematic diagram of the magnetoresistive model of the main magnetic core of the present invention in the ZY section;

[0033] Figure 5 This is a schematic diagram of the π-type model of the magnetic integrated transformer in this invention;

[0034] Figure 6 This is a schematic diagram of the magnetic flux density distribution of the magnetic integrated transformer of the present invention;

[0035] Figure 7 This is a schematic diagram of the magnetic field strength distribution of the magnetic integrated transformer of the present invention;

[0036] Figure 8 This is a schematic diagram of the eddy current loss distribution in the third winding of the magnetic integrated transformer of the present invention;

[0037] Figure 9 This is a schematic diagram of another eddy current loss distribution in the third winding of the magnetic integrated transformer of the present invention;

[0038] Figure 10 This is a schematic diagram showing the eddy current loss distribution of the magnetic integrated transformer of the present invention compared to a traditional transformer;

[0039] Figure 11 This is a schematic diagram showing another eddy current loss distribution of the magnetic integrated transformer of the present invention compared to a traditional transformer. Detailed Implementation

[0040] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0041] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

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

[0043] This invention proposes an adjustable leakage inductance magnetic integrated transformer, a three-port converter, and an on-board charger, aiming to reduce the size of the VCS without sacrificing circuit performance, while meeting the multi-functional charging requirements of the OBC.

[0044] Specifically, the adjustable leakage inductance magnetic integrated transformer proposed in this invention includes a main magnetic core C2, a first winding W1, a second winding W2, and a third winding W3 wound on the main magnetic core C2. The first winding W1 includes a first part W1a and a second part W1b, which are wound on both sides of the main magnetic core C2.

[0045] The second winding W2 is wound in the middle of the main magnetic core C2, and the third winding W3 is overlapped with the second winding W2.

[0046] The first winding W1 and the second winding W2 include an outer winding segment, an inner winding segment, and a cross winding segment. The outer winding segment is wound between the main magnetic core C2 and the third winding W3, the inner winding segment is wound inside the main magnetic core C2, and the cross winding segment connects the outer winding segment and the inner winding segment.

[0047] Among them, a magnetic shunt C1 is provided inside the main magnetic core C2. The magnetic shunt C1 is located between the first winding W1 and the second winding W2 to form a magnetic flux path.

[0048] An air gap is provided between the magnetic shunt C1 and the main magnetic core C2. The air gap is located between one end of the magnetic shunt C1 and the main magnetic core C2, or the air gap is located inside the magnetic shunt C1, or multiple air gaps are provided in the magnetic shunt C1.

[0049] Please see Figure 1This is a schematic diagram of the structure of the magnetic integrated transformer provided by the present invention. The first winding W1 of the magnetic integrated transformer is evenly divided into two parts, namely the first part W1a and the second part W1b. The first part W1a and the second part W1b are symmetrically wound on both sides of the main magnetic core C2, and then the second winding W2 is wound in the middle of the main magnetic core C2.

[0050] The magnetic shunt C1 is inserted between the first part W1a and the second winding W2, and between the second part W1b and the second winding W2. Finally, the third winding W3 is overlapped with the second winding W2 to ensure tight coupling between the third winding W3 and the second winding W2.

[0051] The winding method of the first part W1a, the second part W1b and the third part W2 is that the winding is interlaced outside the window of the main magnetic core C2, non-interlaced inside the window of the main magnetic core C2, and the overlapping area of ​​the main magnetic core C2 and the winding is cross-over. According to this winding method, the winding is divided into external winding segment, internal winding segment and cross winding segment.

[0052] The interleaved winding of the outer winding segments has a high coupling coefficient to counteract the external leakage magnetic field, thereby reducing the eddy current loss of the leakage magnetic field on the third winding W3.

[0053] The non-interleaved winding of the internal winding segments has a low coupling coefficient to form leakage inductance, and the leakage flux is constrained by the magnetic shunt C1.

[0054] According to this winding method, cross-winding segments are unavoidable. The winding can be fixed by the frame. By first winding the first part W1a and the second part W1b, and then winding the second winding W2, the winding sequence from top to bottom in the cross-winding segment area is the third winding W3, the second winding W2, and the first winding W1.

[0055] Based on the above structure, the present invention interweaves the first winding W1 and the second winding W2 at the window of the main magnetic core C2, so that the external magnetic field strength can be canceled, thereby reducing the leakage magnetic field strength in the copper busbar area and reducing the eddy current loss of the copper busbar.

[0056] By winding the first winding W1 and the second winding W2 in a non-interleaved manner to form an effective number of turns, the leakage inductance can be increased. At the same time, by using a magnetic shunt C2, the winding distance between the first winding W1 and the second winding W2 can be effectively reduced without reducing the leakage inductance, resulting in a smaller core size.

[0057] Dividing the first winding W1 into a first part W1a and a second part W1b, and winding it together with the second winding W2, can reduce the length of the cross winding segment, making the structure of the magnetic integrated transformer more symmetrical, which is beneficial to ensuring a high coupling coefficient between the second winding W2 and the third winding W3.

[0058] Optionally, in this invention, the third winding can be made of copper busbars or foil sheets and is flat. The first part W1a, the second part W1b and the second winding W2 are fixed by a frame. The number of turns of the first winding W1 and the second winding W2 can be equal or unequal.

[0059] There is an air gap between the magnetic shunt C1 and the main magnetic core C2. The air gap can be located between one end of the magnetic shunt C1 and the main magnetic core C2, or the air gap can be located inside the magnetic shunt C1. Multiple air gaps can also be set in the magnetic shunt C1. Optionally, the magnetic shunt C1 can have distributed air gaps to control the magnetic field strength in the air gap region.

[0060] Based on the above settings, the equivalent leakage inductance of the internal region of the main magnetic core C2 in this invention satisfies:

[0061]

[0062] Where μ0 is the magnetic permeability in air, h a The window height of the main magnetic core C2, w is the width of the main magnetic core C2, and l is the height of the window of the main magnetic core C2. a l is the horizontal window length of the first part and the second part. b I is the horizontal window length of the second winding. p N is the current on the first winding W1. p H represents the number of turns of the first winding W1. y The magnetic field strength along the length of the main magnetic core C2, V ew The window volume of the main magnetic core C2.

[0063] The magnetic flux of a magnetically integrated transformer satisfies:

[0064]

[0065] Wherein, F1 is the magnetomotive force generated by the first part W1a, R1 is the magnetic reluctance of the first winding W1, R2 is the magnetic reluctance of the second winding W2, R3 is the magnetic reluctance of the third winding W3, Φ1' is the magnetic flux generated solely by the magnetomotive force generated by the first part W1a, and Φ2' is the magnetic flux generated by the magnetomotive forces generated by the second winding W2 and the third winding W3.

[0066] The self-inductance of each winding of the magnetic integrated transformer satisfies:

[0067]

[0068] Among them, L 11 For the self-inductance of the first winding W1, L 22 For the self-inductance of the second winding W2, L 33R1 is the self-inductance of the third winding W3, R2 is the reluctance of the first winding W1, R2 is the reluctance of the second winding W2, R3 is the reluctance of the third winding W3, and N is the reluctance of the third winding W3. p N represents the number of turns in the first winding W1. s N represents the number of turns in the second winding W2. t This refers to the number of turns in the third winding W3.

[0069] The mutual inductance between the windings of the magnetic integrated transformer satisfies:

[0070]

[0071]

[0072] Among them, M 12 For the mutual inductance between the first winding W1 and the second winding W2, M 13 For the mutual inductance between the first winding W1 and the third winding W3, M 23 R1 represents the mutual inductance between the second winding W2 and the third winding W3, R2 represents the reluctance of the first winding W1, R3 represents the reluctance of the second winding W2, and R3 represents the reluctance of the third winding W3. p N represents the number of turns in the first winding W1. s N represents the number of turns in the second winding W2. t This refers to the number of turns in the third winding W3.

[0073] The equivalent inductance and magnetizing inductance of a magnetically integrated transformer satisfy the following:

[0074]

[0075] Among them, L p For the equivalent leakage inductance on the first winding W1 side, L s For the equivalent leakage inductance on the W2 side of the second winding, L t For the equivalent leakage inductance on the W3 side of the third winding, L m Here, A and B are the magnetizing inductance of the integrated magnetic transformer, and A and B are the equivalent turns ratio. M is the magnetizing inductance of the integrated magnetic transformer. 12 For the mutual inductance between the first winding W1 and the second winding W2, M 13 For the mutual inductance between the first winding W1 and the third winding W3, M 23 The mutual inductance between the second winding W2 and the third winding W3.

[0076] The calculation models for parameters such as the equivalent leakage inductance of the internal region of the main magnetic core C2, the magnetic flux of the magnetic integrated transformer, the self-inductance of each winding of the magnetic integrated transformer, the mutual inductance between each winding of the magnetic integrated transformer, the equivalent inductance and the magnetizing inductance of the magnetic integrated transformer are explained below with reference to the accompanying drawings:

[0077] Figure 2This diagram shows the dimensions of the magnetic integrated transformer proposed in this invention, where h is the height of the main magnetic core C2, w is the width of the main magnetic core C2, l is the length of the main magnetic core C2, the length direction of the main magnetic core C2 is defined as the Y direction, the height direction of the main magnetic core C2 is defined as the Z direction, and the width direction of the main magnetic core C2 is defined as the X direction. a Indicates the window height of the main magnetic core C2, l a Indicates the horizontal window length of the first part W1a and the second part W1b, l b The horizontal window length of the W2 region of the second winding is represented by l. a and l b Depending on the winding dimensions of the first winding W1 and the second winding W2, a represents the width of the magnetic shunt C1, b represents the height of the magnetic shunt C1, and δ represents the air gap between the magnetic shunt C1 and the main magnetic core C2.

[0078] Figure 3 The magnetic flux path of the ZY profile of the magnetic integrated transformer is shown, where the excitation flux is represented by Φ. Lm The magnetic flux of the magnetic shunt C1 is expressed as Φ. Lk_shunt Leakage flux is represented by Φ Lk_w , Φ Lk_shunt and Φ Lk_w The path is represented by a dashed line. The total leakage flux of the magnetic integrated transformer is generated by two parts: one part is the leakage flux Φ leaking into the air. Lk_w Part of it is the magnetic flux Φ flowing through the magnetic shunt C1 Lk_shunt The magnetic flux flowing through the left and right columns of the main magnetic core C2 is denoted as Φ1 and Φ2, respectively. Φ1 and Φ2 are formed by the superposition of the excitation magnetic flux and the total leakage magnetic flux.

[0079] Assuming the permeability μ of the main magnetic core C2 r Since the magnetic permeability μ0 is much greater than that of air, the magnetic field strength inside the window C2 of the main magnetic core is much higher than that inside the main magnetic core C2. According to Ampere's circuital law, the magnetic field strength in any y-direction of the ZY section inside the window of the main magnetic core C2 is:

[0080]

[0081] Among them, I p and I s These are the currents in the first winding W1 and the second winding W2, respectively, N. P1 and N S1 Indicates leakage flux Φ Lk_w The number of turns of the first winding W1 and the number of turns of the second winding W2 in the chain-passing region, so as to Figure 3 For example, leakage flux Φ Lk_w Chain through region N p1 =7, N S1 =4,h aThe window height of the main magnetic core C2;

[0082] By integration, the total leakage flux in the window region of the main magnetic core C2 is...

[0083]

[0084] The equivalent leakage inductance of the internal region of the window in the main magnetic core C2 is L. k_w V ew The window volume of the main magnetic core C2 can be used to calculate the equivalent leakage inductance of the internal region of the main magnetic core C2.

[0085]

[0086] Figure 4 The magnetic reluctance model of the magnetically integrated transformer under the ZY profile is shown, based on Ampere's law.

[0087]

[0088] Where MMF is the magnetomotive force, N is the number of turns in the coil, i is the current flowing through the coil, H is the magnetic field strength, and l m Where is the magnetic path length, μ is the permeability, B is the magnetic flux density, Φ is the magnetic flux, and Rm is the equivalent magnetic reluctance.

[0089] Depend on Figure 4 Using Ampere's law, the magnetic reluctance of the magnetic integrated transformer of this invention can be calculated as follows:

[0090]

[0091]

[0092] Among them, R c1 R c2 R c3 These are the equivalent magnetic reluctances (μ) inside the main magnetic core C2. r1 The permeability of the main magnetic core C2, μ0 is the permeability of free space, and l1, l2, l3, l c w, h b R respectively c1 R c2 R c3 The corresponding core size, R shunt μ is the equivalent magnetic reluctance of the magnetic shunt C1. r2 R is the permeability of the magnetic shunt C1. g Let a be the air gap reluctance, and b and w be the dimensions of the magnetic shunt C1.

[0093] Considering the magnetic reluctance cross-sectional area of ​​the air gap diffusion flux, kg is the air gap coefficient related to δ, and in this invention, kg = 1 is taken.

[0094] Let R2 = R shunt +2R g R1 = R c1 +2R c2 R3 = 2R c3 According to Ohm's law for magnetic circuits, the magnetic flux of a magnetically integrated transformer can be calculated to satisfy:

[0095]

[0096] Where F1 represents the magnetomotive force generated by the first part W1a, F1 = N p I p / 2, Φ1' represents the magnetic flux generated by the magnetomotive force F1 produced by the first part W1a alone, F2 and F3 represent the magnetomotive forces generated by the second winding W2 and the third winding respectively, F2=N s I s F3 = N t I t Φ2' represents the magnetic flux generated by the magnetomotive force produced by the second winding W2 and the third winding together. k This represents the magnetic flux flowing through the magnetic shunt C1;

[0097]

[0098] By Faraday's law of electromagnetic induction

[0099]

[0100] Among them, V p V is the voltage across the first winding W1. s V is the voltage across the second winding W2. t This is the voltage across the third winding W3;

[0101] According to the π-type equivalent model of a transformer, we have

[0102]

[0103] Among them, L 11 M represents the self-inductance of the first winding W1. 12 M represents the mutual inductance between the first winding W1 and the second winding W2. 13 M represents the mutual inductance between the first winding W1 and the third winding W3. 23 L represents the mutual inductance between the second winding W2 and the third winding W3. 22 L represents the self-inductance of the second winding W2. 33 Indicates the self-inductance of the third winding W3, i p i represents the current flowing through the first winding W1. s i represents the current flowing through the second winding W2. tThis indicates the current flowing through the third winding W3;

[0104] Expanding the π-type equivalent model, we get:

[0105]

[0106] Figure 5 The equivalent circuit of the magnetic integrated transformer can be simplified to obtain the equivalent inductance and magnetizing inductance of the magnetic integrated transformer, which satisfy the following conditions:

[0107]

[0108] Among them, L p L represents the equivalent leakage inductance on the W1 side of the first winding. s L represents the equivalent leakage inductance on the W2 side of the second winding. t L represents the equivalent leakage inductance on the W3 side of the third winding. m This represents the magnetizing inductance of the integrated magnetic transformer, where A and B are the equivalent turns ratio.

[0109] The overall leakage inductance expression is:

[0110] L k =L p +L k-w

[0111] Accordingly, the present invention can be modified by adjusting Figure 2 The dimensions of the main magnetic core C2 shown can be changed to alter the magnetic reluctance of the main magnetic core C2, thereby adjusting the leakage inductance of the magnetic integrated transformer.

[0112] Figure 6 The finite element simulation diagram of the magnetic flux density distribution of the magnetic integrated transformer is shown. It can be seen that the magnetic flux path of the magnetic integrated transformer is consistent with the magnetic flux path described in this invention. The magnetic shunt C1 can provide a path for leakage flux, thereby shortening the distance between the first winding W1 and the second winding W2 without reducing the leakage inductance, and improving the power density of the magnetic integrated converter.

[0113] In an alternating magnetic field, eddy current loss is proportional to the square of the magnetic induction intensity, the square of the frequency, and the conductivity of the material. By offsetting the external leakage magnetic field through interleaved winding outside the main magnetic core C2, the magnetic induction intensity can be reduced, thereby suppressing the eddy current loss of the leakage magnetic field of the magnetic integrated transformer on the third winding W3. Figure 7The finite element simulation diagram of the magnetic field strength distribution of the magnetic integrated transformer is shown. It can be seen that the magnetic field strength inside the window C2 of the main magnetic core is relatively large due to the non-interleaved windings, as is the magnetic field strength at the air gap of the magnetic shunt C1. By reducing the coupling coefficient of the first winding W1 and the second winding W2 and using the magnetic shunt C1, the leakage inductance of the converter can be designed to meet the ZVS requirement. Outside the magnetic core, due to the interleaved windings, the magnetic field cancels out, thereby reducing the eddy current loss of the copper busbar.

[0114] Figure 8 and Figure 9 The finite element simulation diagram of the eddy current loss distribution of the copper busbar of the magnetic integrated transformer is shown. It can be seen that the eddy current loss generated on the copper busbar is relatively small due to the interlaced winding outside the main magnetic core C2. This is to compare the effect of the present invention. Figure 10 and Figure 11 The diagram shows the distribution of eddy current losses on the copper busbar under conventional transformer winding. It can be seen that the eddy current losses on the copper busbar are relatively high. Due to the eddy current losses, the temperature of the third winding W3 (which is wound through the copper busbar) increases, which is detrimental to the efficiency and thermal management of the OBC.

[0115] As can be seen from the above description, the present invention has the following beneficial effects compared with the prior art:

[0116] 1. In this invention, the first winding W1 and the second winding W2 are interleaved at the window of the main magnetic core C2, so that the external magnetic field strength can be canceled, thereby reducing the leakage magnetic field strength in the copper busbar area and reducing the eddy current loss of the copper busbar.

[0117] 2. In this invention, the first winding W1 and the second winding W2 are wound non-interleaved inside the window of the main magnetic core C2 to form an effective number of turns, which can increase the leakage inductance. At the same time, the magnetic shunt C2 is used to effectively reduce the winding distance of the first winding W1 and the second winding W2 without reducing the leakage inductance, so that the magnetic core size is smaller.

[0118] 3. The present invention divides the first winding W1 into a first part W1a and a second part W1b, and the winding structure wound with the second winding W2 can reduce the length of the cross winding section, making the structure of the magnetic integrated transformer more symmetrical, which is beneficial to ensuring the high coupling coefficient between the second winding W2 and the third winding W3.

[0119] 4. The third winding W3 uses a copper busbar to fully wrap the leakage magnetic area of ​​the main magnetic core C2, which can achieve a magnetic shielding effect, further reduce the eddy current loss of the leakage magnetic field to the internal casing of the on-board charger, and is beneficial to EMC design.

[0120] Furthermore, the present invention can realize an on-board charger through a magnetic integrated transformer. The first winding W1 is connected to the primary-side conversion circuit of the OBC, the second winding W2 is connected to the secondary-side conversion circuit of the OBC, and the third winding W3 is connected to the low-voltage DC conversion circuit. The leakage inductance of the magnetic integrated transformer is used as the power inductance of the OBC, such as in a DAB converter, SRC converter, LLC converter, etc.

[0121] The adjustable leakage inductance magnetic integrated transformer proposed in this invention can include a high-frequency isolation transformer of the OBC, a high-frequency isolation transformer of the LDC, and a power inductor of the OBC. The first winding W1 of the magnetic integrated transformer is set as the primary winding of the OBC high-frequency isolation transformer, the second winding W2 of the magnetic integrated transformer is set as the secondary winding of the OBC high-frequency isolation transformer, and the third winding W3 of the magnetic integrated transformer is set as the secondary winding of the LDC high-frequency isolation transformer. It is universally applicable to OBC topologies with power inductors, such as dual active bridge converters, series resonant converters, and LLC resonant converters.

[0122] The present invention also proposes a three-port converter having the aforementioned magnetically integrated transformer with adjustable leakage inductance.

[0123] The present invention also proposes an on-board charger having the above-mentioned three-port converter.

[0124] 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 within the protection scope of the present invention.

Claims

1. A magnetically integrated transformer with adjustable leakage inductance, comprising a main magnetic core, a first winding, a second winding, and a third winding wound on the main magnetic core, characterized in that, The first winding includes a first part and a second part, which are wound on both sides of the main magnetic core; The second winding is wound in the middle of the main magnetic core, and the third winding is overlapped with the second winding; The first winding and the second winding include an outer winding segment, an inner winding segment, and a cross winding segment. The outer winding segment is wound between the main magnetic core and the third winding. The inner winding segment is wound inside the main magnetic core. The cross winding segment connects the outer winding segment and the inner winding segment. The main magnetic core is equipped with a magnetic shunt, which is located between the first winding and the second winding to form a magnetic flux path.

2. The adjustable leakage inductance magnetic integrated transformer according to claim 1, characterized in that, An air gap is provided between the magnetic shunt and the main magnetic core. The air gap is located between one end of the magnetic shunt and the main magnetic core, or the air gap is located inside the magnetic shunt, or multiple air gaps are provided in the magnetic shunt.

3. The adjustable leakage inductance magnetic integrated transformer according to claim 1, characterized in that, The leakage inductance is adjusted according to the size parameters of the main magnetic core, the size parameters of the magnetic shunt, and the distance between the first winding and the second winding.

4. The adjustable leakage inductance magnetic integrated transformer according to claim 3, characterized in that, The equivalent leakage inductance of the internal region of the main magnetic core satisfies: Where μ0 is the magnetic permeability in air, h a Let w be the window height of the main magnetic core, and l be the width of the main magnetic core. a l is the horizontal window length of the first part and the second part. b I is the horizontal window length of the second winding. p N is the current on the first winding. p H represents the number of turns in the first winding. y V is the magnetic field strength along the length of the main magnetic core. ew Let be the window volume of the main magnetic core.

5. The adjustable leakage inductance magnetic integrated transformer according to claim 1, characterized in that, The equivalent inductance and magnetizing inductance of the magnetic integrated transformer satisfy the following: Among them, L p L is the equivalent leakage inductance on the first winding side. s L is the equivalent leakage inductance on the second winding side. t L is the equivalent leakage inductance on the third winding side. m Let M be the magnetizing inductance of the integrated magnetic transformer, A and B be the equivalent turns ratio, and M be the magnetizing inductance. 12 M represents the mutual inductance between the first winding and the second winding. 13 M is the mutual inductance between the first winding and the third winding. 23 This refers to the mutual inductance between the second winding and the third winding.

6. The magnetically integrated transformer with adjustable leakage inductance according to claim 1, characterized in that, The third winding is made of copper busbars or foil sheets, and the first winding and the second winding are fixed by a frame.

7. The adjustable leakage inductance magnetic integrated transformer according to claim 1, characterized in that, At the cross-wound segment, the winding sequence from top to bottom is the third winding, the second winding, and the first winding.

8. The magnetically integrated transformer with adjustable leakage inductance according to claim 1, characterized in that, The first winding of the magnetic integrated transformer is connected to the primary-side conversion circuit of the on-board charger, the second winding of the magnetic integrated transformer is connected to the secondary-side conversion circuit of the on-board charger, the third winding of the magnetic integrated transformer is connected to the low-voltage DC conversion circuit of the on-board charger, and the leakage inductance of the magnetic integrated transformer serves as the power inductance of the on-board charger.

9. A three-port converter, characterized in that, The three-port converter has a magnetically integrated transformer with adjustable leakage inductance as described in any one of claims 1 to 8.

10. An on-board charger, characterized in that, The on-board charger has a three-port converter as described in claim 9.

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