Three-phase integrated combined electronic transformer

Abstract

The invention relates to the technical field of electronic transformers, in particular to a three-phase integrated combined electronic transformer. Comprising a shell, and three hollow cylinders are arranged in the shell; the zero-sequence iron core is arranged in the shell, the three hollow cylinders all penetrate through the zero-sequence iron core, and a secondary zero-sequence winding is wound on the zero-sequence iron core; the three phase iron cores correspond to three phases and are distributed on one side of the zero-sequence iron core side by side; the three phase iron cores are respectively arranged on the three hollow cylinders, and each phase iron core is wound with a secondary phase winding; the metal net is arranged in the shell and surrounds the secondary zero-sequence winding and the secondary phase winding, and the metal net is grounded; and the secondary zero-sequence winding and the secondary phase winding are coated with the high-permeability material layers. The secondary zero-sequence winding and the secondary phase winding are coated with the high-permeability material layers. The three-phase integrated combined electronic transformer provided by the invention can reduce the interference of an electromagnetic field environment on the accuracy of a product.

Description

Technical Field

[0001] The invention relates to the technical field of electronic mutual inductors, and in particular to a three-phase integrated combined electronic mutual inductor. Background Art

[0002] The three-phase integrated combined electronic current transformer has the characteristics of small size, large measurement range, strong anti-saturation ability, and wide frequency response range, which can better meet the future development needs of smart grids.

[0003] This type of product is usually used in power systems with a rated voltage of 10-35kV, a primary rated current of 100-1200A, and a secondary output of a small voltage signal. According to standard requirements, the secondary outputs are 1V for phase voltage and 0.2V for zero-sequence voltage. The three-phase integrated combined electronic current transformer adopts a three-phase integrated form, with a very compact structure and a complex electromagnetic field environment. The electromagnetic field environment has a greater interference with the product accuracy, especially when the secondary output is a small voltage signal, and the output accuracy requirements are higher. The product output error caused by the external electromagnetic field environment interference will directly lead to the product output accuracy failing to meet the use requirements. Summary of the invention

[0004] The object of the present invention is to provide a three-phase integrated electronic mutual inductor to solve the technical problem raised in the above background technology that the electromagnetic field environment has a significant interference on the accuracy of the product.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a three-phase integrated electronic transformer, comprising: An outer shell, wherein three hollow cylinders are arranged in the outer shell; A zero-sequence iron core is arranged in the shell, the three hollow cylinders all pass through the zero-sequence iron core, and a secondary zero-sequence winding is wound on the zero-sequence iron core; Three phase iron cores, corresponding to three phases and distributed side by side on one side of the zero-sequence iron core; the three phase iron cores are respectively arranged on the three hollow cylinders, and each phase iron core is wound with a secondary phase winding; A metal mesh is arranged in the housing and surrounds the secondary zero-sequence winding and the secondary phase winding, and the metal mesh is grounded; A high magnetic permeability material layer, the secondary zero-sequence winding and the secondary phase winding are both wrapped with the high magnetic permeability material layer.

[0006] Optionally, the zero-sequence iron core is racetrack-shaped.

[0007] Optionally, one side of the housing is open, and the metal mesh includes a main body and a cover; The main body is used to be pre-arranged in the shell through the opening, and the cover is used to be connected with the main body to form an enclosure after the zero-sequence current transformer and the three-phase current transformers are arranged in the shell.

[0008] Optionally, epoxy resin is also included, and the epoxy resin is used to cast the inside of the opening of the shell after the cover part and the main body part are connected.

[0009] Optionally, the high magnetic permeability material layer includes silicon steel sheets.

[0010] Optionally, the metal mesh comprises a brass mesh.

[0011] Optionally, a buffer layer is arranged on the outer side of the phase iron core and / or the zero-sequence iron core.

[0012] Optionally, the buffer layer comprises compressed sponge.

[0013] Optionally, the secondary zero-sequence winding and the secondary phase winding are both connected to a shielded secondary cable for output.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention arranges a high magnetic permeability material layer as a shielding material on both the secondary zero-sequence winding and the secondary phase winding, thereby being able to shunt the external interfering magnetic field and concentrate the magnetic lines of force into the shielding material, thereby preventing the external magnetic field from entering the interior of the high magnetic permeability material layer, reducing the interference of the magnetic field environment on the secondary output signal of the electronic transformer and improving the output accuracy.

[0015] 2. The present invention arranges a complete metal mesh as an enclosing metal shielding body on the outside of the zero-sequence iron core and its winding and the three-phase iron core and its winding, thereby utilizing the induced charges generated by the metal shielding body under the action of the electric field, so that the additional electric field formed by the induced charges and the external electric field are offset, thereby preventing the external electric field from entering the inside of the metal shielding body to reduce the interference of the electric field environment on the secondary output signal of the electronic transformer. At the same time, the grounding of the shielding body in the present invention can introduce the induced charges into the earth to further enhance the shielding effect.

[0016] 3. The present invention can shield the external magnetic field and the external electric field by arranging the high magnetic permeability material layer and the metal mesh at the same time, thereby achieving a better synergistic effect to reduce the interference of the electromagnetic field environment on the accuracy of the product. If only one of the high magnetic permeability material layer and the metal mesh is arranged, the electromagnetic field environment inside the product is still complex, the accuracy of the secondary output is still difficult to guarantee, and it may still be difficult to meet the use requirements due to interference from the external electromagnetic field environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1Schematic diagram of the structure of the three-phase integrated electronic transformer in Example 1; Figure 2 for Figure 1 Schematic diagram of the internal structure of a three-phase integrated electronic transformer; Figure 3 for Figure 2 A cross-sectional schematic diagram of; Figure 4 for Figure 3 Schematic diagram of the structure of the zero-sequence core; Figure 5 for Figure 3 A schematic diagram of the structure of the limiting iron core and the secondary phase winding; Numbers in the figure: 1. Shell; 2. Metal mesh; 3. Phase iron core; 4. Buffer layer; 5. High magnetic permeability material layer; 6. Secondary zero-sequence winding; 7. Epoxy resin; 8. Hollow cylinder; 9. Shielded cable; 10. Zero-sequence iron core; 11. Secondary phase winding. DETAILED DESCRIPTION

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0019] Among the prior arts known to the inventors of the present application, the three-phase integrated combined electronic transformer improves safety performance and measurement accuracy by integrating the phase current transformer and the zero-sequence current transformer of the three phases into one. However, such a compact arrangement leads to a complex electromagnetic field environment, such as the influence of the magnetic flux of the external adjacent conductor and the secondary iron core leakage magnetic influence of the phase current transformer of each phase, as well as the interference caused by the external high voltage. The interference caused by the electromagnetic field environment has a great influence on the output accuracy. Especially when the secondary output voltage is small, such as 200mV, the influence of the electromagnetic field environment on the output accuracy is most obvious. The secondary output voltage of existing products is relatively large. For example, when it is 5V, a layer of semi-conductive paper is wrapped on the outer layer of the secondary winding as a shielding layer, but the shielding effect of such an arrangement is difficult to meet the accuracy requirements of small signal output.

[0020] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Example 1

[0021] from Figure 1 This embodiment provides a three-phase integrated electronic transformer, which includes a housing 1; the housing 1 serves as a structural carrier of the entire electronic transformer, and the housing 1 generally uses a plastic insulator as the housing 1 of the entire electronic transformer.

[0022] Combination Figure 1 In this embodiment, one side of the housing 1 is open (which will be subsequently molded by pouring epoxy resin 7, Figure 1 The housing 1 is already in a cast-molded state), and three hollow cylinders 8 for inserting primary conductors are provided in the housing 1. The housing 1 also has a zero-sequence iron core 10 and three phase iron cores 3. Figure 3 and Figure 4 The zero-sequence iron core 10 is in a racetrack shape, the three hollow cylinders 8 all pass through the zero-sequence iron core 10 , and the zero-sequence iron core 10 is wound with a secondary zero-sequence winding 6 .

[0023] Combination Figure 5 In a specific embodiment, the three phase iron cores 3 correspond to three phases and are distributed side by side on the side of the zero-sequence iron core 10 close to the opening. The three phase iron cores 3 are respectively arranged on the three hollow cylinders 8, and each phase iron core 3 is wound with a secondary phase winding 11. The secondary zero-sequence winding 6 and the secondary phase winding 11 are both connected to a shielded cable 9 to output signals.

[0024] The three-phase integrated electronic transformer of this embodiment is relatively compact in overall layout. The external electromagnetic field has a great influence on the accuracy of the secondary output. Figure 3Furthermore, in order to meet the accuracy requirements of the small signal output under such an arrangement, in this embodiment, a high magnetic permeability material layer 5 is wrapped on the secondary zero-sequence winding 6 and the secondary phase winding 11. The high magnetic permeability material layer 5 is coaxially arranged with the corresponding secondary winding to form a wrap. The purpose of the high magnetic permeability material layer 5 is mainly to shield the external magnetic field to reduce the influence of the magnetic field on the secondary output accuracy.

[0025] Specifically, the high permeability material layer 5 in this embodiment is wrapped around the secondary zero-sequence winding 6 and the secondary phase winding 11 to form a shielding body. Specifically, the magnetic field shielding mainly adopts technical measures to suppress magnetic field coupling to achieve magnetic isolation, and ferromagnetic materials with high magnetic permeability are often used. The main principle of magnetic field shielding is to use high magnetic permeability materials to shunt the interfering magnetic field, so that the magnetic lines of force are concentrated in the shielding body formed by the high permeability material layer 5, thereby weakening the magnetic field in the shielding body.

[0026] In a specific embodiment, the high magnetic permeability material is silicon steel sheet, and materials such as iron and Permalloy can also be selected. The high magnetic permeability material layers 5 in this embodiment can each form a shielding body, and each shielding body can shield the external magnetic field to avoid the influence of the magnetic flux of the external adjacent conductor and the leakage of each secondary iron core (zero sequence iron core 10 and three phase iron cores 3) and affect the remaining secondary iron cores.

[0027] Furthermore, in addition to the influence of the external magnetic field, the external electric field will also affect the secondary output accuracy of the entire transformer. Therefore, a metal mesh 2 is also arranged in this embodiment. Figure 2 The metal mesh 2 is arranged in the housing 1 and surrounds the secondary zero-sequence winding 6 and the secondary phase winding 11 ( Figure 2 The metal mesh 2 is not shown completely, and actually except for the three hollow cylinders 8, other parts including the areas between adjacent hollow cylinders 8 are surrounded by the metal mesh 2), and the metal mesh 2 is grounded.

[0028] In order to shield the external electric field and reduce high-voltage interference in this embodiment, a metal shield is formed by adding a metal mesh 2 and grounding the metal mesh 2. The metal shield generates induced charges under the action of the electric field. The additional electric field formed by the induced charges can offset the external electric field, thereby preventing the external electric field from entering the interior of the metal shield, so as to reduce the interference of the external electric field on the secondary output of the phase voltage and the secondary output of the zero-sequence voltage. At the same time, the grounding of the shield can introduce the induced charges into the earth, thereby enhancing the shielding effect. In a specific embodiment, the metal mesh 2 includes a brass mesh.

[0029] This embodiment can make the electric field inside the metal mesh 2 zero, thereby shielding the external electric field to prevent the external electric field from entering the interior. In addition, the metal mesh 2 also has the function of uniform electric field. When installed in the switch cabinet, it can uniform the electric field in that part to reduce the amount of partial discharge, thereby further reducing interference.

[0030] Since the metal mesh 2 needs to surround the secondary zero-sequence winding 6 and the secondary phase winding 11 to reduce interference, a split metal mesh 2 is used for assembly in this embodiment. One side of the housing 1 in this embodiment is open, and the metal mesh 2 includes a main body and a cover. Figure 2 , Figure 2 The metal mesh 2 shown in the figure is the cover body, which is connected to the main body at one side of the notch of the housing 1. The assembly process of the entire electronic transformer is described below: Step S1: Arrange the main body of the metal mesh 2 in the outer shell 1 through the opening of the outer shell 1, and reserve gaps on the main body corresponding to the three hollow cylinders 8; Step S2: Arrange the racetrack-shaped zero-sequence core 10 wound with the zero-sequence secondary winding in the housing 1 through the opening, and the three hollow cylinders 8 are all located inside the zero-sequence core 10. The zero-sequence secondary winding can be directly against the metal mesh 2 of the main body, or a gap can be reserved.

[0031] Step S3: installing the three phase iron cores 3 on the three hollow cylinders 8 respectively; Step S4: Connect and fix the cover part and the main body of the metal mesh 2, and reserve gaps at the corresponding positions of the cover part and the three hollow cylinders 8; at this time, the complete metal mesh 2 can fully surround the zero-sequence iron core 10 and its secondary winding and the phase iron core 3 and its secondary winding, thereby achieving a better magnetic field shielding effect.

[0032] Step S5: pouring epoxy resin 7 from the notch of the housing 1 inward to form a final electronic transformer. Example 2

[0033] The present embodiment is different from the present embodiment in that a buffer layer 4 is arranged outside the phase core 3 and / or the zero sequence core 10 in the present embodiment. The purpose of arranging the buffer layer 4 is to prevent the phase core 3 or the zero sequence core 10 from being squeezed due to the shrinkage of the resin due to temperature changes, thereby affecting the output accuracy of the product. In a specific embodiment, the buffer layer 4 includes a compressed sponge.

[0034] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A three-phase integrated electronic transformer, characterized in that: include: An outer shell (1), wherein three hollow cylinders (8) are arranged inside the outer shell (1); A zero-sequence iron core (10) is disposed in the housing (1), the three hollow cylinders (8) all pass through the zero-sequence iron core (10), and a secondary zero-sequence winding (6) is wound around the zero-sequence iron core (10); Three phase iron cores (3), corresponding to three phases and arranged side by side on one side of the zero-sequence iron core (10); the three phase iron cores (3) are respectively arranged on the three hollow cylinders (8), and each phase iron core (3) is wound with a secondary phase winding (11); A metal mesh (2) is arranged in the housing (1) and surrounds both the secondary zero-sequence winding (6) and the secondary phase winding (11), and the metal mesh (2) is grounded; A high magnetic permeability material layer (5), wherein the secondary zero-sequence winding (6) and the secondary phase winding (11) are both wrapped with the high magnetic permeability material layer (5).

2. The three-phase integrated electronic transformer according to claim 1, characterized in that: The zero-sequence iron core (10) is in a racetrack shape.

3. The three-phase integrated electronic transformer according to claim 2, characterized in that: One side of the housing (1) is open, and the metal mesh (2) comprises a main body portion and a cover portion; The main body is used to be pre-arranged in the housing (1) through the opening, and the cover is used to be connected to the main body to form an enclosure after the zero-sequence current transformer and the three-phase current transformers are arranged in the housing (1).

4. The three-phase integrated electronic transformer according to claim 3, characterized in that: It also includes epoxy resin (7), which is used to cast the inside of the opening of the shell (1) after the cover part and the main body part are connected.

5. The three-phase integrated electronic transformer according to claim 1, characterized in that: The high magnetic permeability material layer (5) comprises silicon steel sheets.

6. A three-phase integrated electronic transformer according to claim 1, characterized in that: The metal mesh (2) comprises a brass mesh.

7. A three-phase integrated electronic transformer according to claim 1, characterized in that: A buffer layer (4) is arranged on the outer side of the phase iron core (3) and / or the zero-sequence iron core (10).

8. A three-phase integrated electronic transformer according to claim 7, characterized in that: The buffer layer (4) comprises compressed sponge.

9. A three-phase integrated electronic transformer according to claim 1, characterized in that: The secondary zero-sequence winding (6) and the secondary phase winding (11) are both connected to a shielded cable (9) for output.

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