Dual-input current transformer and manufacturing method thereof

Abstract

The invention discloses a dual-input current transformer and a manufacturing method thereof, the dual-input current transformer comprises a primary winding A, a primary winding B, a secondary winding and a magnetic core, the primary winding A, the primary winding B and the magnetic core are respectively connected with the secondary winding, and the primary winding B is connected with the primary winding A. The secondary winding is wrapped by the primary winding A and the primary winding B, so that primary and secondary magnetoelectric coupling is increased, and the conversion efficiency of the current transformer is improved. The cross-sectional areas of the pin leading-out ends of the primary winding A1 and the primary winding B are large, so that the cross-sectional areas of the coils can be increased, and the maximum input current can be improved. The current transformer prepared by the invention has a relatively small volume, the space utilization rate is improved, and the whole transformer has the characteristics of high reliability, high stability, high power transmission efficiency, low loss and the like, and accords with the development trend of miniaturization and high conversion efficiency design.

Description

Technical Field

[0001] The invention belongs to the technical field of current transformers, and in particular relates to a dual-input current transformer and a manufacturing method thereof. Background Art

[0002] With the arrival of the third-generation semiconductor era, the operating frequency of electronic circuits is getting higher and higher, and the transformers are getting smaller and smaller. Module miniaturization will become the trend of the future electronics industry. Reducing the size of the two current transformers will greatly improve the module space utilization. In order to solve this difficult problem, a dual-input miniature current transformer is needed.

[0003] Dual-input miniature current transformers (hereinafter referred to as dual-input current transformers) are mainly used in power systems, industrial fields, aerospace, communications and other fields. They play the role of current conversion, power system protection, and monitoring system operation status in the circuit. They are new products that meet the market's low-cost and miniaturized development needs. This type of transformer can achieve dual-channel input of large current in a limited space, and has the advantages of miniaturization, system structure optimization, and cost savings. It has broad potential markets and application prospects.

[0004] The patent document with announcement number CN211125311U discloses a 1A and 5A shared miniature current transformer, which consists of an iron core, two primary windings, one secondary winding, a plastic frame and a pin. The two primary windings and one secondary winding are wound on the same iron core at the same time, and the primary winding is directly led out as the input end. The two primary windings are used for inputs with rated current values ​​of 1A and 5A respectively, and the number of winding turns of the winding used for 1A input is 5 times that of the 5A input winding. The lead wire of the secondary winding is connected to the pin fixed at the bottom of the plastic frame and serves as the output end. The miniature current transformer can share one miniature current transformer in the two input conditions of 1A and 5A without basically increasing the size and cost. The plug-in equipped with this miniature current transformer can adapt to the two conditions of 1A and 5A, and it is no longer necessary to distinguish between the two AC input plug-ins rated for 1A and rated for 5A. The current transformer can only input currents of 1A and 5A, and cannot achieve bilateral large current input. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a dual-input current transformer and a manufacturing method thereof.

[0006] The present invention is achieved through the following technical solutions.

[0007] The dual-input current transformer provided by the present invention comprises a primary winding A, a primary winding B, a secondary winding, and a magnetic core, wherein the primary winding A, the primary winding B, and the magnetic core are respectively connected to the secondary winding.

[0008] Preferably, the secondary winding comprises a skeleton and an enameled wire, pins are arranged on both ends of the skeleton, the enameled wire is wound on the skeleton to form a coil, and both ends of the enameled wire are respectively connected to the pins.

[0009] Preferably, the skeleton includes a connecting column and a connecting plate, both ends of the connecting column are respectively connected through the connecting plate, a groove A is arranged on the connecting column, the groove A passes through the connecting column, the enameled wire is wound on the connecting column, and the pin is arranged on the connecting plate.

[0010] Preferably, the coil surface is wrapped with polytetrafluoroethylene tape.

[0011] Preferably, the primary winding A is made of copper flat wire, a placement slot A is provided on the primary winding A, and the secondary winding is placed in the placement slot A for connection.

[0012] The primary winding B is made of a copper welding sheet, a placement groove B is provided on the primary winding B, and the primary winding A is placed in the placement groove B for connection.

[0013] Preferably, the magnetic core comprises two magnetic core pieces connected symmetrically, a groove B is provided on the magnetic core piece, and the magnetic core piece is in an E shape.

[0014] Preferably, the magnetic core is made of manganese-zinc ferrite material, and a polyimide film is arranged between the primary winding A and the primary winding B.

[0015] A method for preparing a dual-input current transformer comprises the following steps:

[0016] S1: Cut off the extra pins on the frame, use enameled wire to evenly wind the secondary winding on the connecting column to form a coil, then buckle it into the magnetic core, and wrap 1-2 layers of polytetrafluoroethylene tape on the surface of the coil to form the secondary winding.

[0017] S2: Connect the primary winding A to the secondary winding, set a polyimide film outside the primary winding A, connect the primary winding B to the primary winding A, fix the current transformer, and then apply adhesive to the bends of the lead ends of the primary winding A and the primary winding B and the bends of the pins.

[0018] S3: Perform high temperature curing.

[0019] Preferably, the high temperature curing step comprises curing at a temperature of 120-170° C. for 50-70 min.

[0020] The beneficial effects of the present invention are:

[0021] The purpose of the present invention is to increase the primary and secondary magnetoelectric coupling by wrapping the secondary winding with the primary winding A and the primary winding B, thereby improving the conversion efficiency of the current transformer. The cross-sectional area of ​​the pin lead-out end of the primary winding A1 and the primary winding B is relatively large, which can increase the cross-sectional area of ​​the coil and increase the maximum input current. The current transformer prepared by the present invention has a relatively small volume, improves the space utilization rate, and the entire transformer has the characteristics of high reliability, high stability, high power transmission efficiency and low loss, which conforms to the development trend of miniaturization and high conversion efficiency design. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the present invention;

[0023] Figure 2 It is a schematic diagram of the top view of the structure of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of the present invention when viewed from above;

[0025] Figure 4 It is a side structural schematic diagram of the present invention;

[0026] Figure 5 It is a structural schematic diagram of the primary winding A and the secondary winding of the present invention;

[0027] Figure 6 It is a schematic diagram of the structure after the primary winding B is installed in the present invention;

[0028] Figure 7 It is a schematic diagram of the connection between the primary winding A and the secondary winding of the present invention;

[0029] Figure 8 is an exploded view of the present invention;

[0030] Fig. 9 is an exploded view of the present invention;

[0031] Fig.10 It is a structural schematic diagram of the skeleton and coil of the present invention;

[0032] In the figure: 1-primary winding A, 11-placement slot A, 2-primary winding B, 21-placement slot B, 3-secondary winding, 31-enameled wire, 4-magnetic core, 41-magnetic core piece, 42-groove B, 5-skeleton, 51-pin, 52-connecting column, 53-connecting plate, 54-groove A. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0034] Embodiment 1:

[0035] like Figures 1 to 10As shown, the dual-input current transformer includes a primary winding A1, a primary winding B2, a secondary winding 3, and a magnetic core 4. The primary winding A1, the primary winding B2, and the magnetic core 4 are respectively connected to the secondary winding 3. An insulating film is arranged between the primary winding B2 and the primary winding A1, and the winding lines of the primary winding A1 and the primary winding B2 do not interfere with each other.

[0036] The secondary winding 3 includes a frame 5 and an enameled wire 31. Pins 51 are arranged at both ends of the frame 5. The enameled wire 31 is wound on the frame 5 to form a coil. Both ends of the enameled wire 31 are respectively connected to the pins 51. The frame 5 is an EE05 frame with 6 seagull pins 51.

[0037] The skeleton 5 includes a connecting column 52 and a connecting plate 53. Both ends of the connecting column 52 are respectively connected through the connecting plate 53. A groove A54 is set on the connecting column 52. The groove A54 passes through the connecting column 52. The enameled wire 31 is wound on the connecting column 52. The pin 51 is set on the connecting plate 53.

[0038] The coil surface is wrapped with 1-2 layers of polytetrafluoroethylene tape as a buffer layer.

[0039] The primary winding A1 is prepared by stacking polyimide copper flat wires with a height×width size of 0.15 mm×2.5 mm. A placement groove A11 is provided on the primary winding A1, and the secondary winding 3 is placed in the placement groove A11 for connection.

[0040] The primary winding B2 is made of EE5-4 copper welding sheet, a placement groove B21 is set on the primary winding B2, the primary winding A1 is placed in the placement groove B21 for connection, and a snap structure is set on the winding B2, which is connected and fixed to the frame 5 through the snap structure.

[0041] The magnetic core 4 comprises two magnetic core pieces 41 connected symmetrically, and the magnetic core piece 41 is provided with grooves B42, two grooves B42 are symmetrically provided, and the magnetic core piece 41 has two parallel planes and wings extending outward on both sides, and the magnetic core piece 41 is in the shape of E. The middle convex part of the magnetic core piece 41 can be inserted into the groove A54 for fixing.

[0042] The material of the magnetic core 4 is TPW33 manganese-zinc ferrite material with a Curie temperature of 220° C., high initial magnetic permeability, high Curie temperature, low resistivity, etc., which is suitable for the characteristic conditions of high-frequency mutual inductor.

[0043] A polyimide film is arranged between the primary winding A1 and the primary winding B2.

[0044] A method for preparing a dual-input current transformer comprises the following steps:

[0045] S1: Use a cutting tool to cut off the four redundant pins 51 on the EE05 frame 5. The secondary winding 3 is made of an enameled wire 31 with a temperature resistance grade of 180°C, which is evenly wound on the connecting column 52 to form a coil, and then buckled into the magnetic core 4. Wrap 1-2 layers of polytetrafluoroethylene tape on the surface of the coil for buffering to form the secondary winding 3.

[0046] S2: Shape the primary winding A1 and then lead out the primary winding B2, the lead is hexagonal, the primary winding A1 is connected to the secondary winding 3, a layer of polyimide film is arranged outside the primary winding A1, the primary winding B2 is connected to the primary winding A1, the current transformer is fixed by a special tool, and then the adhesive is applied to the bends of the lead ends of the primary winding A1 and the primary winding B2 and the bends of the lead 51;

[0047] S3: Perform high temperature curing.

[0048] The high temperature curing step includes curing at a temperature of 120-170°C for 50-70 minutes. During the high temperature curing, a curing glue is used to cure the shape of the primary winding A1. The curing process and curing glue are relatively mature technologies. The existing technology can be selected according to the specific capacitor model to be prepared, and will not be repeated in this application.

[0049] The EE05C700050X transformer is prepared by the method of the present invention, and its length×width×height dimensions are 8.38mm×7.5mm×5.5mm. The maximum input current of this transformer is 6A, and the current transformer is not prevented from overheating during operation. According to the current density J=16A / mm 2 The following requirements are required for design, and the cross-sectional area of ​​the copper flat wire winding of the primary winding A1 is Sp ≥ 0.375mm 2 ; When the frequency becomes higher, the current distribution is uneven, and most of the current will be concentrated near the surface of the conductor. The skin depth e=66.1 / √f, the thickness H needs to be less than 2e, and when the operating frequency is 200kHz, that is, H<0.29mm. Since the sum of the primary winding A1 and the primary winding B2 is equal to 0.4mm, which exceeds the specified 2 times skin depth, select 0.15mm thick copper flat wire and copper welding sheet, which meet its requirements.

[0050] The dual-input transformer has high requirements for pin shaping. Irregular shaping will cause the polyimide tape to be damaged and the distance between the two pins 51 to be small, which will affect the insulation performance of the transformer and cause interference and short circuit between the transformers. The enameled copper round wire 31 in the secondary winding 3 needs to be evenly arranged to ensure that the primary winding A1 and the primary winding B2 can be well coupled to avoid inaccurate secondary winding measurement.

[0051] Comparative Example 1:

[0052] Two commercially available TF6R04-EE05C30050 transformers are connected as a single input transformer.

[0053] Comparative Example 2:

[0054] A single commercially available PULSE dual input current transformer.

[0055] The dual-input current transformer prepared in Example 1 is compared with the existing domestic TF6R04-EE05C30050 current transformer and the imported PULSE dual-input current transformer in accordance with GJB2829A-2013 "General Specification for Audio, Power and High-Power Pulse Transformers and Inductors", as shown in the following table.

[0056] Compare Projects Example 1 Comparative Example 1 Comparative Example 2 length ≦8.8mm ≦17.8mm ≦12.83mm width ≦7.5mm ≦14.4mm ≦12.57mm high ≦6.0mm ≦12.0mm ≦7.11mm weight <0.8g <1.6g <1.56g Input Current ≦6A ≦6A ≦6A Operating temperature range -55℃-130℃ -55℃-130℃ -40℃-120℃

[0057] It can be seen from the above table that the current transformer prepared in Example 1 of the present application is small in size and weight, and can also input 6A current in both directions. Moreover, its operating temperature range is greater than that of the imported PULSE dual-input current transformer, and has better performance.

Claims

1. Dual-input current transformer, characterized in that: It comprises a primary winding A (1), a primary winding B (2), a secondary winding (3), and a magnetic core (4); the primary winding A (1), the primary winding B (2), and the magnetic core (4) are respectively connected to the secondary winding (3).

2. The dual-input current transformer according to claim 1, characterized in that: The secondary winding (3) comprises a frame (5) and an enameled wire (31), pins (51) are arranged at both ends of the frame (5), the enameled wire (31) is wound on the frame (5) to form a coil, and both ends of the enameled wire (31) are respectively connected to the pins (51).

3. The dual-input current transformer according to claim 2, characterized in that: The skeleton (5) comprises a connecting column (52) and a connecting plate (53), the two ends of the connecting column (52) respectively penetrate the connecting plate (53) for connection, a groove A (54) is provided on the connecting column (52), the groove A (54) penetrates the connecting column (52), the enameled wire (31) is wound on the connecting column (52), and the pin (51) is provided on the connecting plate (53).

4. The dual-input current transformer according to claim 2, characterized in that: The surface of the coil is wrapped with polytetrafluoroethylene tape.

5. The dual-input current transformer according to claim 1, characterized in that: The primary winding A (1) is made of copper flat wire, a placement slot A (11) is provided on the primary winding A (1), and the secondary winding (3) is placed in the placement slot A (11) for connection.

6. The dual-input current transformer according to claim 1, characterized in that: The primary winding B (2) is made of a copper welding sheet. A placement groove B (21) is provided on the primary winding B (2). The primary winding A (1) is placed in the placement groove B (21) for connection.

7. The dual-input current transformer according to claim 1, characterized in that: The magnetic core (4) comprises two magnetic core pieces (41) connected symmetrically, a groove B (42) is provided on the magnetic core piece (41), and the magnetic core piece (41) is in an E shape.

8. The dual-input current transformer according to claim 1, characterized in that: The magnetic core (4) is made of manganese-zinc ferrite material, and a polyimide film is provided between the primary winding A (1) and the primary winding B (2).

9. The method for preparing a dual-input current transformer according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Cut off the redundant pins (51) on the frame (5), use the enameled wire (31) to evenly wind the secondary winding (3) on the connecting column (52) to form a coil, then buckle it into the magnetic core (4), and wrap 1-2 layers of polytetrafluoroethylene tape on the surface of the coil to form the secondary winding (3); S2: connecting the primary winding A (1) to the secondary winding (3), arranging a polyimide film outside the primary winding A (1), connecting the primary winding B (2) to the primary winding A (1), fixing the current transformer, and then applying adhesive to the bending parts of the lead ends of the primary winding A (1) and the primary winding B (2) and the bending parts of the pins (51); S3: Perform high temperature curing.

10. The method for preparing a dual-input current transformer according to claim 9, characterized in that: The high temperature curing step includes curing at a temperature of 120-170° C. for 50-70 minutes.

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