A transformer

Abstract

The present invention discloses a transformer, comprising an iron core and an inner coil and an outer coil coaxially sleeved on the core column of the iron core. The inner coil is a pancake-shaped coil, and the inner coil has an inner lead wire extending from the innermost winding of the inner coil toward the center of the inner coil, while the outer coil has an outer lead wire extending radially from the outermost winding of the outer coil toward the outside of the outer coil. This transformer structure enables both the inner lead wire and the outer lead wire to be located in a position with a relatively weak magnetic field strength, thereby greatly reducing the eddy current loss of the terminals of the inner lead wire and the outer lead wire. In addition, the structure of the above-mentioned transformer enables the inner lead wire to be shielded by the electric field of the inner coil, and the outer lead wire to be shielded by the electric field of the outer coil, effectively reducing the main insulation size between the inner coil and the outer coil, thereby optimizing the insulation between the inner coil and the outer coil.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and more particularly to a transformer. Background Art

[0002] The main body of a transformer consists of an iron core and coils. The iron core is the transformer's main magnetic circuit and also serves as the coil's skeleton. The coil, the circuit component of the transformer, is made of copper and aluminum wire wound through the main magnetic circuit. The transformer consists of an inner coil and an outer coil coaxially sleeved on the core legs. Insulation requirements must be met both within the coil and between the inner and outer coils.

[0003] Pancake coils are commonly used for medium-high-frequency, medium-voltage, and large-capacity transformers. Pancake coils are typically wound with flat wire, with the coil turns radially forming a pancake and then arranged axially. Pancake coils offer excellent heat dissipation, high mechanical strength, and convenient wiring, making them suitable for a wide range of applications. Currently, to reduce eddy current losses in the coils, transformer coils are often wound with multi-strand enameled wire. However, due to paint stripping in a tinning oven and crimping of the terminals, the multi-strand characteristic is lost. Furthermore, the current wiring for the inner coil is typically routed outward from the inner coil end, which further degrades the insulation between the inner and outer coils.

[0004] In summary, how to solve the problem of high eddy current loss and insulation deterioration in the coil output of the transformer has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a transformer to solve the problems of high eddy current loss and insulation deterioration in the coil output of the transformer.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A transformer comprises an iron core and an inner coil and an outer coil coaxially sleeved on the iron core column of the iron core, wherein the inner coil is a pancake-shaped coil, and the lead-out method of the inner coil is an inner lead-out wire led out from the innermost winding layer of the inner coil toward the center side of the inner coil, and the lead-out method of the outer coil is an outer lead-out wire led out radially from the outermost winding layer of the outer coil toward the outside of the outer coil.

[0008] Optionally, the inner coil includes at least one inner coil unit, the number of coils of the inner coil unit is an even number, the number of turns of each coil is at least one turn, and the innermost winding of each inner coil unit is led out toward the center side of the inner coil unit to form a first unit lead-out wire.

[0009] Optionally, the inner coil includes a plurality of inner coil units, and the first unit lead wires of the inner coil units are connected in series, in parallel, or in a combination of series and parallel to form the inner lead wires.

[0010] Optionally, the inner coil includes a plurality of inner coil units, and each inner coil unit is led out as an independent coil through a first unit lead-out wire.

[0011] Optionally, the current introduction end and the current lead-out end of the first unit lead-out wire of the inner coil unit are arranged in an up-down staggered manner.

[0012] Optionally, the inner coil unit has two coils, and each coil has at least two turns.

[0013] Optionally, the outer coil is a pancake-shaped coil, and the outer coil includes at least one outer coil unit, the number of coils in the outer coil unit is an even number, the number of turns of each coil is at least one turn, and the outermost winding of each outer coil unit is radially led out to the outside of the outer coil unit to form a second unit lead-out wire.

[0014] Optionally, the outer coil includes a plurality of outer coil units, and the second unit lead wires of the respective outer coil units are connected in series, in parallel, or in a combination of series and parallel to form the outer lead wire.

[0015] Optionally, the outer coil includes a plurality of outer coil units, and each outer coil unit is led out as an independent coil through a second unit lead-out line.

[0016] Optionally, the current introduction end and the current lead-out end of the second unit lead-out wire of the outer coil unit are arranged in an up-down staggered manner.

[0017] Optionally, the outer coil unit has two coils, and each coil has at least two turns.

[0018] Optionally, the inner lead wires and the outer lead wires are arranged in a staggered manner.

[0019] Optionally, the number of the core columns of the iron core is at least one, and the inner coil and the outer coil are coaxially sleeved on each of the core columns.

[0020] Optionally, the cable used for the inner coil is a multi-strand twisted enameled wire;

[0021] And / or, the cable used for winding the outer coil is a multi-strand twisted enameled wire.

[0022] Optionally, the inner coil is a low-voltage coil, and the outer coil is a high-voltage coil.

[0023] Compared with the background technology introduction, the above-mentioned transformer includes an iron core and an inner coil and an outer coil coaxially sleeved on the iron core column of the iron core. The inner coil is a pancake coil, and the lead-out method of the inner coil is an inner lead-out wire led out from the innermost winding of the inner coil toward the center side of the inner coil, and the lead-out method of the outer coil is an outer lead-out wire radially led out from the outermost winding of the outer coil toward the outside of the outer coil. In actual application of this transformer, since the inner coil is a pancake coil, the lead-out method of the inner coil can be wound in a forward and reverse pancake manner to form an inner lead-out wire that is led out from the innermost layer of the inner coil toward the center side of the inner coil, that is, the inner lead-out wire is located on the inner side of the inner coil. At the same time, the lead-out method of the outer coil is an outer lead-out wire that is radially led out from the outermost layer of the outer coil toward the outer side of the outer coil, that is, the outer lead-out wire is located on the outside of the outer coil. According to the typical magnetic field distribution rule of the transformer, the magnetic field intensity between the primary coil and the secondary coil is the highest, and the electric field intensity inside the primary coil and outside the secondary coil is close to zero. The higher the magnetic field intensity of the wire is, the stronger its The stronger the proximity effect, the higher the eddy current loss. Therefore, the inner lead wire of the inner coil is located on the inner side of the inner coil, which can make the inner lead wire be in a position with weaker magnetic field strength, and the outer lead wire of the outer coil is located on the outside of the outer coil, which can make the outer lead wire also be in a position with weaker magnetic field strength, thereby greatly reducing the eddy current loss of the terminals of the inner lead wire and the outer lead wire. In addition, the structural form of the above-mentioned transformer can make the inner lead wire be shielded by the electric field of the inner coil, and the outer lead wire be shielded by the electric field of the outer coil, effectively reducing the main insulation size between the inner coil and the outer coil, thereby optimizing the insulation between the inner coil and the outer coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0025] Figure 1 A schematic diagram of the axial structure of the inner coil unit provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the main structure of the inner coil unit provided by an embodiment of the present invention;

[0027] Figure 3 for Figure 2 A1 direction view;

[0028] Figure 4 for Figure 2 A2 direction view;

[0029] Figure 5 A schematic diagram of the main structure of the outer coil unit provided in an embodiment of the present invention;

[0030] Figure 6 for Figure 5 B1 direction view;

[0031] Figure 7 for Figure 5 B2 direction view;

[0032] Figure 8 A schematic diagram of a top view of a transformer provided in an embodiment of the present invention;

[0033] Figure 9 A schematic diagram of the main structure of a transformer provided in an embodiment of the present invention, which uses two core legs to respectively house a single inner coil unit and a single outer coil unit;

[0034] Figure 10 A schematic diagram of the main structure of a transformer provided in an embodiment of the present invention, which uses two core legs to respectively house three inner coil units and three outer coil units, each of which is led out as an independent coil;

[0035] Figure 11 A schematic diagram of the main structure of the transformer provided in an embodiment of the present invention, in which the first unit lead wires of each inner coil unit are led out in series, and the second unit lead wires of each outer coil unit are led out in series;

[0036] Figure 12 A schematic diagram of the main structure of the transformer provided in an embodiment of the present invention, in which the first unit lead wires of each inner coil unit on the core column are led out in parallel and the second unit lead wires of each outer coil unit are led out in parallel.

[0037] in, Figures 1-12 middle:

[0038] Iron core 1, iron core column 11;

[0039] Inner coil 2, inner coil unit 20, first unit lead wire 201, inner lead wire 21;

[0040] The outer coil 3 , the outer coil unit 30 , the second unit lead wire 301 , and the outer lead wire 31 . DETAILED DESCRIPTION

[0041] The core of the present invention is to provide a transformer to solve the problems of high eddy current loss and insulation deterioration in the coil output of the transformer.

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Reference Figures 1-12 The present invention specifically provides a transformer, including an iron core 1 and an inner coil 2 and an outer coil 3 coaxially sleeved on an iron core column 11 of the iron core 1, wherein the lead-out method of the inner coil 2 is an inner lead-out wire 21 led out from the innermost winding of the inner coil 2 toward the center side of the inner coil 2, and the lead-out method of the outer coil 3 is an outer lead-out wire 31 radially led out from the outermost winding of the outer coil 3 toward the outside of the outer coil 3.

[0044] In actual application of this transformer, since the inner coil 2 is a pancake coil, the lead-out method of the inner coil 2 can be wound in a forward and reverse pancake manner to form an inner lead-out line 21 led out from the innermost layer of the inner coil 2 toward the center side of the inner coil 2, that is, the inner lead-out line 21 is located on the inner side of the inner coil 2, and at the same time, the lead-out method of the outer coil 3 is an outer lead-out line 31 radially led out from the outermost layer of the outer coil 3 toward the outer side of the outer coil 3, that is, the outer lead-out line 31 is located on the outside of the outer coil 3. According to the typical magnetic field distribution rule of the transformer, the magnetic field intensity between the primary coil and the secondary coil is the highest, and the electric field intensity inside the primary coil and outside the secondary coil is close to zero, and the higher the magnetic field intensity of the wire is, the greater its proximity effect. The stronger the magnetic field is, the higher the eddy current loss is. Therefore, the inner lead wire 21 of the inner coil 2 is located on the inner side of the inner coil 2, which can make the inner lead wire 21 be in a position with weaker magnetic field strength, and the outer lead wire 31 of the outer coil 3 is located on the outside of the outer coil 3, which can make the outer lead wire 31 also be in a position with weaker magnetic field strength, thereby greatly reducing the eddy current loss of the terminals of the inner lead wire 21 and the outer lead wire 31. In addition, the structural form of the above-mentioned transformer can make the inner lead wire 21 be shielded by the electric field of the inner coil 2, and the outer lead wire 31 be shielded by the electric field of the outer coil 3, effectively reducing the main insulation size between the inner coil 2 and the outer coil 3, thereby optimizing the insulation between the inner coil 2 and the outer coil 3.

[0045] It should be noted that the inner coil 2 is generally a low-voltage coil, while the outer coil 3 is generally a high-voltage coil. Of course, it is understood that when the transformer has special structural requirements, the inner coil 2 can also be a high-voltage coil and the outer coil 3 a low-voltage coil. In actual application, specific configurations can be made based on actual needs, and no further specific restrictions are given here.

[0046] In some specific embodiments, reference Figures 1-4 The inner coil 2 may specifically include at least one inner coil unit 20, the number of coils in the inner coil unit 20 is an even number, the number of turns of each coil is at least one turn, and the innermost winding of each inner coil unit 20 is led out toward the center side of the inner coil unit 20 and forms a first unit lead wire 201. By designing the inner coil 2 into the above-mentioned structural form, when applied to a transformer, the inner coil 2 can select a corresponding number of inner coil units 20 according to actual needs, and the specific number is not limited. For example, you can refer to Figure 8 and Figure 9 As shown, an inner coil unit 20 is mounted on the core column 11 of the core 1. Figure 10-12 As shown, three inner coil units 20 are mounted on the core column 11 of the core 1. Of course, the number may be two or more.

[0047] In a further embodiment, when the inner coil 2 includes a plurality of inner coil units 20, the first unit lead wires 201 of each inner coil unit 20 can be connected in series, in parallel, or in a combination of series and parallel to form an inner lead wire 21. In actual application, specific configuration can be made according to actual needs. For example, referring to Figure 11 As shown, the first unit lead wires 201 of each inner coil unit 20 are connected in series to form the inner lead wire 21. By connecting in series, the number of turns of the inner coil 2 can be expanded. For coils with a large number of turns, the above-mentioned two groups of inner coil units 20 with multiple layers can be adopted, but this may increase the thickness of the coil and reduce the power density; in this case, it is also possible to preferably use the first unit lead wires 201 of multiple inner coil units 20 to be connected in series in the low magnetic field area using terminals, thereby reducing the eddy current loss at the short circuit. The structure of forming multiple wire cakes in series simplifies the process, and reasonable splitting can achieve higher power density. For example, referring to Figure 12 As shown, the first unit lead wires 201 of each inner coil unit 20 are connected in parallel to form the inner lead wires 21, which can increase the number of strands of the inner coil 2. Of course, a combination of series and parallel connections can also be used. For example, the first unit lead wires 201 of each inner coil unit 20 can be connected in parallel first and then in series, or in series first and then in parallel. Alternatively, some inner coil units 20 can be independently output while others can be connected in series and parallel.

[0048] In other specific embodiments, when the inner coil 2 includes multiple inner coil units 20, each inner coil unit 20 can also be designed to be an independent coil and led out through the first unit lead-out line 201. The independent output of multiple inner coil units 20 can achieve multi-channel independent use. For example, the application scenario can be that the charging station draws power from the high-voltage power grid, the high-voltage side coil (i.e., the outer coil) adopts H-bridge post-cascade connection, and the low-voltage coil (i.e., the inner coil unit 20) is independently used as a multi-channel charging pile coil. This method is not shown in detail.

[0049] In some specific embodiments, reference Figures 9-11 As shown, the current lead-in end and the current lead-out end of the first unit lead-out wire 201 of the inner coil unit 20 can be designed to be staggered up and down, thereby achieving insulation between the current lead-in end and the current lead-out end of the inner coil unit 20 .

[0050] In some more specific embodiments, the number of coils in the inner coil unit 20 is preferably 2, and the number of turns of each coil is at least two. The inlet and outlet wires can be on the inner side of the coil, which is convenient for outlet wires and does not require an extra turn of space to achieve cross-layer inlet and outlet wires as in traditional solutions. Figures 1-4 , take the example of two turns per coil, since the inlet and outlet terminals are on the inside, Figure 2 Looking from the A1 direction, the winding method is: Figure 3 The winding direction of the first cake is a (current introduction end) → b → c → ... → k, winding outward in the counterclockwise direction; refer to Figure 2 , go around to the second cake in the direction k→L; Figure 2 Looking from the A2 direction, the winding direction is L→m→n→…→v (current lead-out end), winding inward in a clockwise direction. This structure can be achieved by forward and reverse pancake winding.

[0051] In some more specific embodiments, reference Figure 5-Figure 7 The outer coil 3 may also be a pancake coil, which may include at least one outer coil unit 30. The outer coil unit 30 has an even number of coils, each coil has at least one turn, and the outermost winding of each outer coil unit 30 is radially led outward from the outer coil unit 30 to form a second unit lead wire 301. By designing the outer coil 3 into the above-mentioned structural form, when applied to a transformer, the outer coil 3 can select a corresponding number of outer coil units 30 according to actual needs, and the specific number is not limited. For example, you can refer to Figure 8 and Figure 9 As shown, an outer coil unit 30 is mounted on the core column 11 of the core 1. Figure 10-12As shown, three outer coil units 30 are mounted on the core column 11 of the core 1, and of course, there may be two or more outer coil units 30.

[0052] In a further embodiment, when the outer coil 3 includes a plurality of outer coil units 30, the second unit lead wires 301 of each outer coil unit 30 are connected in series, in parallel, or in a combination of series and parallel to form an outer lead wire 31. In actual application, specific configuration can be made according to actual needs. For example, referring to Figure 11 As shown, the second unit lead wires 301 of each outer coil unit 30 are connected in series to form an outer lead wire 31. By connecting in series, the number of turns of the outer coil 3 can be expanded. For coils with a large number of turns, the above-mentioned two groups of outer coil units 30 with multiple layers can be adopted, but this may increase the thickness of the coil and reduce the power density; in this case, it is also possible to adopt the second unit lead wires 301 of multiple outer coil units 30 to be connected in series using terminals in the low magnetic field area, thereby reducing the eddy current loss at the short circuit. The structure of forming multiple wire cakes in series simplifies the process, and reasonable splitting can achieve higher power density. For example, referring to Figure 12 As shown, the second unit lead wires 301 of each outer coil unit 30 are connected in parallel to form the outer lead wires 31, which can increase the number of strands of the outer coil 3. Of course, a combination of series and parallel connections can also be used. For example, the second unit lead wires 301 of each outer coil unit 30 can be connected in parallel first and then in series, or in series first and then in parallel. Alternatively, some outer coil units 30 can have independent outputs while others can be connected in series and parallel.

[0053] In other specific embodiments, when the outer coil 3 includes multiple outer coil units 30, each outer coil unit 30 can be designed to be independently connected as an independent coil through the second unit lead-out line 301. The independent output of multiple outer coil units 30 can achieve multi-channel independent use. For example, the application scenario can be that the charging station draws power from the high-voltage power grid, the high-voltage side coil (i.e., the outer coil) adopts H-bridge cascade connection, and the low-voltage coil (i.e., the inner coil unit 20) is independently used as a multi-channel charging pile coil. This method is not shown in detail.

[0054] It should be noted that, in addition to the above combination, there is also a combination scheme where the inner coil is a pancake coil and the outer coil is a layer coil, which also falls within the scope of protection of the present invention. For this combination scheme, a corresponding diagram is provided.

[0055] In some specific embodiments, reference Figures 9-11As shown, the current input end and the current output end of the second unit lead wire 301 of the outer coil unit 30 can be designed to be staggered up and down, thereby achieving insulation between the current input end and the current output end of the outer coil unit 30.

[0056] In some more specific embodiments, the number of coils in the outer coil unit 3 is preferably 2, and the number of turns of each coil is at least two. The inlet and outlet wires can be on the inner side of the coil, which is convenient for outlet and simple for winding. Figure 5-Figure 7 Taking the number of turns of each coil as two as an example, there is no need to reserve an extra turn of space to achieve the cross-layer of the incoming and outgoing wires as in the traditional solution. The structure is basically the same as the traditional pancake coil. The patent of this invention takes into account the characteristics of multi-strand enameled wire and prefers a simple coil structure of 2 coils and multiple layers. The coil turning process can be avoided as much as possible during winding. The specific operation is: take the midpoint of the wire, start winding from the innermost layer, and then Figure 5 Looking in the direction of B1, combined Figure 6 The winding direction is opposite to the current flow direction, that is, through K→J→I→H→G→F→E→D→C→B→A, from Figure 5 Looking from the B2 direction, combined with Figure 7 , following the current flow direction L→M→N→O→P→Q→R→S→T→U→V. The winding process for both coils is from the inside out, making it easier to wind. For coils with more turns, the number of layers can be increased, and the winding process is basically the same.

[0057] In some other specific embodiments, the inner lead wires and the outer lead wires may be designed to be staggered, thereby improving the insulation performance between the inner lead wires and the outer lead wires.

[0058] It should be noted that in actual application, the number of core columns 11 of the iron core 1 of the above-mentioned transformer is at least one, and can be one or more. The specific number can be configured according to actual needs, and each core column 11 is coaxially sleeved with the above-mentioned inner coil 2 and outer coil 3.

[0059] It should also be noted that the cable used for the inner coil 2 is preferably a multi-strand twisted enameled wire; similarly, the cable used for the outer coil 3 is also preferably a multi-strand twisted enameled wire. The pancake coil uses multi-strand twisted enameled wire to reduce the eddy current loss of the coil during high-frequency applications. The specific number of groups and layers of the pancake structure can be determined based on the actual material of the wire and the pancake turning process. Figure 1-Figure 7 As shown, the two-layer pancake structure allows for easy flipping, minimizes stress, and prevents damage to the multi-stranded enameled wire. When a single coil has a large number of turns or strands, it can be split into multiple simple pancake coils connected in series or parallel. Of course, suitable tooling can also be designed to reduce the difficulty of flipping multi-turn coils.

[0060] In addition, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0061] It should be understood that the use of "system," "device," "unit," and / or "module" in this application is merely a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0062] As used in this application and the claims, unless the context clearly indicates an exception, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular and may include the plural, unless the context clearly indicates otherwise. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements. The phrase "comprises a..." does not preclude the presence of additional identical elements in the process, method, product, or apparatus that includes the elements.

[0063] In the description of the embodiments of this application, unless otherwise specified, " / " represents or. For example, A / B can represent A or B. "And / or" in this article is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of this application, "plurality" means two or more than two.

[0064] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0065] If a flow chart is used in this application, the flow chart is used to illustrate the operations performed by the system according to the embodiments of the application. It should be understood that the previous or subsequent operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. At the same time, other operations can be added to these processes, or one or more operations can be removed from these processes.

[0066] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A transformer comprising an iron core (1) and an inner coil (2) and an outer coil (3) coaxially sleeved on an iron core column (11) of the iron core (1), characterized in that: The inner coil is a pancake-shaped coil, and the inner coil (2) has an inner lead wire (21) extending from the innermost winding of the inner coil (2) toward the center of the inner coil (2), and the outer coil (3) has an outer lead wire (31) extending radially from the outermost winding of the outer coil (3) toward the outside of the outer coil (3). The inner coil (2) is a low-voltage coil, and the outer coil (3) is a high-voltage coil; or the inner coil (2) is a high-voltage coil, and the outer coil (3) is a low-voltage coil.

2. The transformer according to claim 1, characterized in that The inner coil (2) comprises at least one inner coil unit (20), the number of coils of the inner coil unit (20) is an even number, the number of turns of each coil is at least one turn, and the innermost winding of each inner coil unit (20) is led out toward the center side of the inner coil unit (20) to form a first unit lead-out wire (201).

3. The transformer according to claim 2, characterized in that The inner coil (2) comprises a plurality of inner coil units (20), and the first unit lead wires (201) of the respective inner coil units (20) are connected in series, in parallel, or in a combination of series and parallel to form the inner lead wires (21).

4. The transformer according to claim 2, wherein: The inner coil (2) comprises a plurality of inner coil units (20), and each inner coil unit (20) is led out as an independent coil through a first unit lead-out line (201).

5. The transformer according to claim 2, wherein: The current introduction end and the current lead-out end of the first unit lead-out wire (201) of the inner coil unit (20) are arranged in an upper and lower staggered manner.

6. The transformer according to claim 2, wherein: The inner coil unit (20) has two coils, and each coil has at least two turns.

7. The transformer according to claim 1, wherein: The outer coil (3) is a pancake-shaped coil, and the outer coil comprises at least one outer coil unit (30), the number of coils of the outer coil unit (30) is an even number, the number of turns of each coil is at least one turn, and the outermost winding of each outer coil unit (30) is radially led outward from the outer side of the outer coil unit (30) to form a second unit lead-out wire (301).

8. The transformer according to claim 7, characterized in that The outer coil (3) comprises a plurality of outer coil units (30), and the second unit lead wires (301) of the respective outer coil units (30) are connected in series, in parallel, or in a combination of series and parallel to form the outer lead wire (31).

9. The transformer according to claim 7, wherein: The outer coil (3) includes a plurality of outer coil units (30), and each outer coil unit (30) is led out as an independent coil through a second unit lead-out line (301).

10. The transformer according to claim 7, wherein: The current introduction end and the current lead-out end of the second unit lead-out wire (301) of the outer coil unit (30) are arranged in an upper and lower staggered manner.

11. The transformer according to claim 7, wherein: The outer coil unit (3) has two coils, and each coil has at least two turns.

12. The transformer according to claim 1, wherein: The inner lead wires and the outer lead wires are arranged in a staggered manner.

13. The transformer according to claim 1, wherein: The number of the core column (11) of the iron core (1) is at least one, and the inner coil (2) and the outer coil (3) are coaxially sleeved on each of the core columns (11).

14. The transformer according to claim 1, wherein The cable used for the inner coil (2) is a multi-strand twisted enameled wire; And / or, the cable used to wind the outer coil (3) is a multi-strand twisted enameled wire.

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