A current transformer
By optimizing the magnetic circuit of the current transformer through modular design and insulation structure, the problems of high magnetic resistance and low production efficiency in the existing technology have been solved, realizing the production of high-precision and low-cost current transformers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MORNSUN GUANGZHOU SCI & TECH
- Filing Date
- 2025-07-23
- Publication Date
- 2026-07-28
AI Technical Summary
Existing current transformers have an air gap during the core assembly process, which results in high magnetic reluctance, affects accuracy, and leads to low production efficiency and high cost.
The design adopts a modular approach, using a ring-shaped magnetic ring and a skeleton sleeve structure. The positioning function of the skeleton sleeve allows the primary coil and the secondary coil to form an assembly structure with a height difference, avoiding contact. A safe distance is ensured through insulation devices or insulation potting structures, thus optimizing the magnetic circuit design.
It reduces magnetic resistance by more than 30%, improves measurement accuracy to within ±1%, increases production efficiency, reduces costs by 15%, and increases yield by 4%.
Smart Images
Figure CN224569842U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electronic components technology, specifically to a current transformer. Background Technology
[0002] With the continuous advancement of technology, the precision requirements for power supplies and various testing equipment are becoming increasingly stringent, which also necessitates higher precision in current transformers. Reducing the magnetic core reluctance is a highly effective method to improve the accuracy of current transformers. However, existing current transformers using an EE-like structure inherently have air gaps during core assembly, preventing the magnetic circuit from fully closing and resulting in high reluctance. Using a toroidal magnetic ring, which naturally creates a closed magnetic circuit, reduces the reluctance.
[0003] However, during the production of magnetic ring structure current transformers, the assembly efficiency of the primary coil is very low, and many defects are generated, leading to increased costs. Based on this, this invention optimizes the current transformer structure and proposes a modular current transformer with low magnetic reluctance. Utility Model Content
[0004] The present invention aims to overcome at least one of the defects in the prior art and provide a low magnetic reluctance modular current transformer to facilitate and improve efficiency and reduce failure rate.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A current transformer includes a magnetic ring, a primary coil, and a secondary coil, and also includes a frame. The frame includes a square plate-shaped base, terminals, and two sleeves protruding from the base. The magnetic ring is a toroidal magnetic core. The primary coil is U-shaped and formed by bending a metal conductor, forming two legs. The secondary coil is wound around the magnetic ring, which is fitted onto one of the sleeves of the frame. The two legs of the primary coil are inserted into the two sleeves of the frame and extend from the bottom surface of the base. The primary coil is supported and positioned by the sleeves in an assembly position where it will not come into contact with the secondary coil.
[0007] Preferably, the current transformer further includes an insulating device made of high-temperature resistant plastic material, which is sleeved on the surface of the primary coil and / or the sleeve to limit the movement of the primary coil and the sleeve.
[0008] Preferably, the current transformer further includes an insulating device made of bakelite injection molding, which is wrapped around the surface of the primary coil to limit the movement of the primary coil and the sleeve.
[0009] Preferably, the distance between the primary coil and the secondary coil is greater than 0.3 mm; and / or the protruding portion of the primary coil extending out of the bottom surface of the frame base is at the same height as the terminal.
[0010] Preferably, the two sleeves of the skeleton are cylindrical, one located at the edge and the other at the middle.
[0011] Preferably, the height of the sleeve of the skeleton is greater than or equal to 1.0 mm; and / or the inner hole of the sleeve of the skeleton is a two-stage stepped hole structure, and the cross-sectional area of the upper hole is greater than the cross-sectional area of the lower hole.
[0012] Preferably, the skeleton is integrally molded from high-temperature resistant bakelite material.
[0013] Preferably, the base is divided into two areas: a welding area and a non-welding area, with the terminals of the base located in the welding area; and / or the thickness of the welding area is less than or equal to 0.8 mm, and the thickness of the non-welding area is less than or equal to 1.4 mm.
[0014] Preferably, the central hole of the magnetic ring is circular, square, or polygonal in shape.
[0015] Preferably, the terminal is a double-ended metal pin or a surface-mount pin.
[0016] Preferably, the primary coil is made of a single metal conductor; or is made of multiple metal conductors connected in parallel; and / or the primary coil is made of one or more of copper, aluminum, silver, gold, or alloys, and has an outer layer coated with an electroplated layer.
[0017] The beneficial effects of this utility model of current transformer are as follows:
[0018] 1. Magnetic circuit optimization: Through the design of a gapless closed magnetic circuit, there is no air magnetic resistance, the overall magnetic resistance is reduced by more than 30%, and the measurement accuracy is improved to within ±1%.
[0019] 2. Module structure compatibility: The sleeve and port sizes are matched, supporting the use of primary coils of various specifications and forms, expanding application scenarios.
[0020] 3. Production efficiency: The diverse shapes of the magnetic ring openings (circular, square, etc.) and the pre-designed ports and sleeves simplify the assembly process and reduce production costs by 15%.
[0021] 4. Improved yield: The height difference design between the primary and secondary coils avoids electrical short circuits and coil damage during assembly, resulting in a 4% improvement in yield. Attached Figure Description
[0022] Figure 1 This is a perspective view of the current transformer of this utility model;
[0023] Figure 2 This is a perspective view of the secondary coil and magnetic ring of the current transformer of this utility model;
[0024] Figure 3This is a perspective view of the frame of the current transformer according to Embodiment 1 of this utility model;
[0025] Figure 4 This is a cross-sectional view of the frame sleeve of the current transformer according to Embodiment 1 of this utility model;
[0026] Figure 5 This is a perspective view of the primary coil of the current transformer according to Embodiment 1 of this utility model;
[0027] Figure 6 This is a cross-sectional view of the current transformer according to Embodiment 1 of this utility model;
[0028] Figure 7 This is a three-dimensional exploded view of the current transformer according to Embodiment 2 of this utility model;
[0029] Figure 8 This is a three-dimensional structural diagram of the primary coil of the current transformer according to Embodiment 2 of this utility model;
[0030] Figure 9 This is a cross-sectional view of the current transformer according to Embodiment 2 of this utility model;
[0031] Figure 10 This is a perspective view of the current transformer according to Embodiment 3 of this utility model;
[0032] Figure 11 This is a three-dimensional exploded view of the current transformer according to Embodiment 3 of this utility model;
[0033] Figure 12 This is a cross-sectional view of the current transformer according to Embodiment 3 of this utility model.
[0034] The reference numerals in the above figures are explained as follows:
[0035] 100 Frame, 101 Base, 102 Terminal, 103 Sleeve, 104 Port (Internal Hole)
[0036] 200 magnetic ring, 201 center hole
[0037] 300 secondary coil, 301 starting end, 302 taking end
[0038] 400 Primary coil, 401 Side leg, 402 Crossbeam, 403 Insulation device Detailed Implementation
[0039] The present invention and its beneficial effects will be further described in detail below with reference to specific embodiments and accompanying drawings. However, the specific embodiments of the present invention are not limited thereto.
[0040] Please see Figures 1 to 6The current transformer of this utility model includes a magnetic ring 200, a primary coil 400, and a secondary coil 300, as well as a frame 100. The frame 100 includes a square plate-shaped base 101, terminals 102, and two sleeves 103 protruding from the base. The magnetic ring 200 is a toroidal magnetic core. The primary coil 400 is U-shaped and formed by bending a metal conductor, resulting in two legs 401. The secondary coil 300 is wound around the magnetic ring 200, which is fitted onto one of the sleeves 103 of the frame 100. The two legs 401 of the primary coil are inserted into the two sleeves 103 of the frame and extend from the bottom surface of the base. The primary coil 400 is supported and positioned by the sleeves 103 in an assembly position where it will not contact the secondary coil 300. Alternatively, the primary coil 400 is supported and positioned by the sleeves 103 at a position slightly higher than the secondary coil 300, so as to form a stable, non-contact safety distance between the two coils through the height difference in their assembly and positioning.
[0041] The two sleeves 103 of the frame are cylindrical, one located at the edge and the other at the center. Preferably, the inner hole of the sleeve has a two-stage stepped hole structure, with the cross-sectional area of the upper hole being larger than that of the lower hole. The height of the sleeve is greater than or equal to 1.0 mm to ensure that the assembly position of the primary coil is supported and positioned by the sleeve within a safe distance range that will not cause contact with the secondary coil. The frame 100 is integrally molded from high-temperature resistant bakelite material.
[0042] The central hole 201 of the magnetic ring is circular, square, or polygonal in shape.
[0043] Terminal 102 is a double-ended protruding metal pin or a surface-mount pin.
[0044] The base 101 is divided into two areas: a welding area and a non-welding area. The terminals of the base are located in the welding area. The thickness of the welding area is less than or equal to 0.8 mm, and the thickness of the non-welding area is less than or equal to 1.4 mm.
[0045] The primary coil 400 is made of a single metal conductor or multiple metal conductors connected in parallel. The primary coil is made of one or more of copper, aluminum, silver, gold, or alloys, and is coated with an electroplated layer.
[0046] Preferably, the distance between the primary coil 400 and the secondary coil 300 is greater than 0.3 mm, that is, the distance H between the inner wall of the side leg 401 of the primary coil 400 and the secondary coil is greater than 0.3 mm, so as to ensure a safe distance between the primary and secondary coils to prevent them from contacting each other. The protruding part of the primary coil 400 extending out of the bottom surface of the base of the frame 100 is at the same height as the terminal 102.
[0047] In this embodiment, the current transformer may further include an insulating device made of high-temperature resistant plastic material, which is sleeved on the surface of the primary coil and / or the sleeve to limit the primary coil and the sleeve, so as to ensure a safe distance between the primary and secondary coils to prevent them from contacting each other.
[0048] In other embodiments, the current transformer may also include an insulating device made of bakelite injection molding, which wraps around the surface of the primary coil to limit the primary coil and the sleeve.
[0049] This invention relates to a current transformer that, through the positioning function of the frame sleeve, creates an assembly structure with a height difference between the primary and secondary coils, ensuring a safe distance that prevents contact between them. The air-gap characteristic of the toroidal magnetic ring reduces magnetic reluctance, while the modular design of the frame and primary coil optimizes production efficiency. The frame employs a through-hole design within the sleeve to ensure efficient assembly of the magnetic ring and primary coil. The secondary coil is wound on a high-permeability magnetic ring and connected to the frame terminals, while the primary coil passes through the magnetic ring port via a side-leg structure for current conduction. Therefore, this invention's current transformer features low magnetic reluctance, high precision, easy assembly, and strong scalability.
[0050] Example 1:
[0051] like Figure 1 As shown, a low magnetic reluctance modular current transformer includes a frame 100, a magnetic ring 200, a secondary coil 300, and a primary coil 400.
[0052] like Figure 3 , Figure 4 As shown, the frame is made of high-temperature resistant bakelite to ensure that the frame does not deform after welding and baking. It consists of four parts: a base 101, two terminals 102, two sleeves 103, and two ports 104. The two ports 104 are connected to the central holes of the respective sleeves 103.
[0053] The base 101 is divided into a welding area with a thickness of 0.8mm and a non-welding area with a thickness of 1.4mm; the terminal 102 is a plug-in terminal, made of copper-clad steel with an electroplated tin layer, and is a cylinder with a diameter of 0.8mm and a height of 4.3mm; the shortest distance between the edge of the terminal 102 and the non-welding area is 2.5mm; the sleeve 103 is a cylinder with a height of 4.3mm, in which the hole cross-section is a circle with a diameter of 1.6mm, and the distance from the edge of the hole to the outer periphery of the sleeve 103 is 0.45mm; the port 104 has a cross-section with a diameter of 1.3mm, and its center overlaps with the center of the hole cross-section of the sleeve 103.
[0054] like Figure 2As shown, the magnetic ring 200 is made of manganese zinc ferrite with a permeability of 10000. The magnetic ring 200 is circular in shape and is coated with epoxy resin with a thickness of 0.12mm on the outside. Its inner diameter is 4.75mm, the outer diameter is 9.5mm, and the height is 3.2mm.
[0055] like Figure 2 As shown, the secondary coil 300 is made of enameled wire with a polyurethane enameled coating and copper conductor. Its outer diameter is 0.15 mm, and it is wound with 50 turns. After winding, the starting end 301 and the taking end 302 are connected to the two terminals 102 of the bobbin 100, respectively, and finally fixed by solder. After winding, the inner hole of the secondary coil 300 can accommodate a cylinder with a diameter of 4.2 mm, and the outer circle has a maximum diameter of 10.2 mm and a height of 3.9 mm.
[0056] like Figure 5 , Figure 6 As shown, the primary coil 400 is made of one or more of copper, aluminum, silver, gold, or alloys, with an outer electroplated layer. It includes two side legs 401 and a crossbeam 402. One side leg 401 passes through the port 104 inside the magnetic ring 200, and the other side leg 401 passes through the outside of the magnetic ring 200, connected by the crossbeam 402. The crossbeam 402 serves as a limiter only by the sleeve 103. The side legs 401 are cylindrical with a diameter of 1.2 mm and a height of 7.3 mm, and the crossbeam 402 is cylindrical with a diameter of 1.2 mm and a length of 8.2 mm.
[0057] Finally, the sleeve 103 and the primary coil 400 in the frame 100 are fixed with epoxy resin; and the base 101 in the frame 100 is fixed with the secondary coil with epoxy resin.
[0058] Example 2
[0059] like Figure 7 , Figure 8 , Figure 9 The image shows a current transformer according to Embodiment 2 of this utility model. The difference from Embodiment 1 is that the assembly structure that forms a safe distance between the primary and secondary coils to prevent contact is different; this embodiment uses an insulation device. Specifically, a low magnetic reluctance modular current transformer includes a frame 100, a magnetic ring 200, a secondary coil 300, and a primary coil 400.
[0060] like Figure 7 As shown, the frame is made of high-temperature resistant bakelite to ensure that the frame does not deform after welding and baking. It consists of four parts: a base 101, two terminals 102, two sleeves 103, and two ports 104. The two ports 104 are connected to the central holes of the respective sleeves 103.
[0061] The base 101 is divided into a welding area with a thickness of 0.8mm and a non-welding area with a thickness of 1.4mm; the terminal 102 is a plug-in terminal, made of copper-clad steel with an electroplated tin layer, and is a cylinder with a diameter of 0.8mm and a height of 4.3mm; the shortest distance between the edge of the terminal 102 and the non-welding area is 2.5mm; the sleeve 103 is a cylinder with a height of 2.5mm, in which the hole cross-section is a circle with a diameter of 1.6mm, and the distance from the edge of the hole to the outer periphery of the sleeve 103 is 0.45mm; the port 104 has a cross-section with a diameter of 1.3mm, and its center overlaps with the center of the cross-section of the hole in the sleeve 103.
[0062] like Figure 2 As shown, the magnetic ring 200 is made of manganese zinc ferrite with a permeability of 10000. The magnetic ring 200 is circular in shape and is coated with epoxy resin with a thickness of 0.12mm on the outside. Its inner diameter is 4.75mm, the outer diameter is 9.5mm, and the height is 3.2mm.
[0063] like Figure 7 As shown, the secondary coil 300 is made of enameled wire with a polyurethane enameled coating and copper conductor. Its outer diameter is 0.15 mm, and it is wound with 50 turns. After winding, the starting end 301 and the taking end 302 are connected to the two terminals 102 of the bobbin 100, respectively, and finally fixed by solder. After winding, the inner hole of the secondary coil 300 can accommodate a cylinder with a diameter of 4.2 mm, and the outer circle has a maximum diameter of 10.2 mm and a height of 3.9 mm.
[0064] like Figure 8 , Figure 9 As shown, the primary coil 400 includes two side legs 401 and a crossbeam 402, on which an insulating device 403 is fitted. The insulating device 403 is made of Teflon and passes through the side legs 401, the crossbeam 402, and the sleeve 103.
[0065] One side leg 401 passes through the port 104 inside the magnetic ring 200, and another side leg 401 passes through the outside of the magnetic ring 200, connected by a crossbeam 402, wherein the insulating device 403 acts as a limit between the primary coil and the sleeve.
[0066] The primary coil 400 is made of one or more of copper, aluminum, silver, gold, or alloys, and is coated with an electroplated layer. The side leg 401 is a cylinder with a diameter of 1.2 mm and a height of 7.3 mm, and the crossbeam 402 is a cylinder with a diameter of 1.2 mm and a length of 8.2 mm.
[0067] Finally, the sleeve 103 and the primary coil 400 in the frame 100 are fixed with epoxy resin; and the base 101 in the frame 100 is fixed with the secondary coil with epoxy resin.
[0068] Example 3
[0069] like Figure 10 , Figure 11 , Figure 12 As shown, this is a current transformer according to Embodiment 3 of the present invention. The difference between this embodiment and Embodiments 1 and 2 lies in the assembly structure that forms a safe distance between the primary and secondary coils to prevent contact. This embodiment employs a partial insulation potting structure. Specifically, a low magnetic reluctance modular current transformer includes a frame 100, a magnetic ring 200, a secondary coil 300, and a primary coil 400.
[0070] like Figure 10 As shown, the frame is made of high-temperature resistant bakelite to ensure that the frame does not deform after welding and baking. It consists of four parts: a base 101, two terminals 102, two sleeves 103, and two ports 104. The two ports 104 are connected to the central holes of the respective sleeves 103.
[0071] The base 101 is divided into a soldering area with a thickness of 0.8mm and a non-soldering area with a thickness of 1.4mm; the terminal 102 is a surface mount terminal made of phosphor bronze with an electroplated tin layer, and is an L-shaped terminal with a length of 1.5mm and a width of 0.8mm; the shortest distance between the edge of the terminal 102 and the non-soldering area is 2.5mm; the sleeve 103 is a cylindrical body with a height of 4.3mm, and the central hole cross-section is a circle with a diameter of 2.6mm, and the distance from the edge of the central hole to the outer periphery of the sleeve 103 is 0.45mm, and the outer periphery diameter of the sleeve 103 is 3.5mm; the port 104 has a cross-section with a diameter of 1.3mm, and its center overlaps with the center of the central hole cross-section of the sleeve 103.
[0072] like Figure 10 As shown, the magnetic ring 200 is made of manganese zinc ferrite with a permeability of 10000. The magnetic ring 200 is circular in shape and is coated with epoxy resin with a thickness of 0.12mm on the outside. Its inner diameter is 4.75mm, the outer diameter is 9.5mm, and the height is 3.2mm.
[0073] like Figure 10 As shown, the secondary coil 300 is made of enameled wire with a polyurethane enameled coating and copper conductor. Its outer diameter is 0.15 mm, and it is wound with 50 turns. After winding, the starting end 301 and the taking end 302 are connected to the two terminals 102 of the bobbin 100, respectively, and finally fixed by solder. After winding, the inner hole of the secondary coil 300 can accommodate a cylindrical sleeve 103 with a diameter of 4.2 mm and an outer diameter of 3.5 mm, and the outer circle can be as large as a circle with a diameter of 10.2 mm and a height of 3.9 mm.
[0074] like Figure 12As shown, the primary coil 400 includes two side legs 401 and a crossbeam 402, which is covered with an insulating device 403. The insulating device 403 is made of bakelite, is injection molded, and has a thickness of 0.45mm. It covers part of the side legs 401 and the entire crossbeam 402, and there is a 3.8mm gap below the side legs 401 that is not covered.
[0075] One side leg 401 passes through the port 104 inside the magnetic ring 200, and another side leg 401 passes through the outside of the magnetic ring 200, connected by a crossbeam 402, wherein the insulating device 403 acts as a limit between the sleeve 103 and the primary coil 400.
[0076] The primary coil 400 is made of copper with an outer tin-plated layer. The side leg 401 is a cylinder with a diameter of 1.2 mm and a height of 7.3 mm, and the crossbeam 402 is a cylinder with a diameter of 1.2 mm and a length of 8.2 mm.
[0077] Finally, the sleeve 103 and the primary coil 400 in the frame 100 are fixed with epoxy resin; and the base 101 in the frame 100 is fixed with the secondary coil with epoxy resin.
[0078] In summary, this utility model of current transformer, through the size constraints of the sleeve 103 and the port 104, ensures that the positions of the secondary coil 300 and the primary coil 400 are relatively fixed, avoiding the risk of dimensional defects caused by assembly work. It also ensures that the primary and secondary coils do not contact, preventing voltage withstand failure. Experiments have shown that the defect rate is reduced by 4% compared to similar products. Through the limitation of the magnetic permeability of the magnetic ring 200 and the closed-loop magnetic circuit, due to the gapless closed magnetic circuit design and the absence of air resistance, the overall magnetic resistance is reduced by more than 30%, and the measurement accuracy is improved to within ±1%, thereby reducing magnetic resistance and improving the accuracy of the current transformer. The primary coil 400 can be configured with multiple modes of insulation device assembly structures to meet different insulation requirements for the safe distance setting of the primary and secondary coils, and can optimize and simplify the assembly process, reducing production costs by 15%.
[0079] The above embodiments are only used to help understand the method and core idea of this utility model. For those skilled in the art, other equivalent application schemes that can be naturally associated with the above description and examples without departing from the principle of this invention, as well as some improvements and modifications to this utility model, all fall within the protection scope of the claims of this utility model / invention.
Claims
1. A current transformer, comprising a magnetic ring, a primary coil, and a secondary coil, characterized in that: It also includes the skeleton, The frame includes a square plate-shaped base, terminals, and two sleeves protruding from the base. The magnetic ring has a toroidal magnetic core. The primary coil is U-shaped and is made of bent metal conductor, forming two legs. The secondary coil is wound on a magnetic ring, which is fitted onto a sleeve of the frame. The two legs of the primary coil are inserted into the two sleeves of the frame and extend out of the bottom surface of the base. The primary coil is supported and positioned by the sleeves in an assembly position where it will not come into contact with the secondary coil.
2. The current transformer according to claim 1, characterized in that: It also includes an insulating device made of high-temperature resistant plastic material, which is fitted onto the surface of the primary coil and / or sleeve to limit the movement of the primary coil and sleeve.
3. The current transformer according to claim 1, characterized in that: It also includes an insulating device made of bakelite injection molding, which is wrapped around the surface of the primary coil to limit the primary coil and the sleeve.
4. The current transformer according to claim 1, characterized in that: The distance between the primary coil and the secondary coil is greater than 0.3 mm; and / or the protruding part of the primary coil extending out of the bottom surface of the frame base is at the same height as the terminal.
5. The current transformer according to claim 1, characterized in that: The two sleeves of the skeleton are cylindrical, one located at the edge and the other at the middle.
6. The current transformer according to claim 1, characterized in that: The height of the sleeve of the skeleton is greater than or equal to 1.0 mm; and / or the inner hole of the sleeve of the skeleton is a two-stage stepped hole structure, and the cross-sectional area of the upper hole is greater than the cross-sectional area of the lower hole.
7. The current transformer according to claim 1, characterized in that: The frame is made of high-temperature resistant bakelite material in one piece.
8. The current transformer according to claim 1, characterized in that: The base is divided into two areas: a welding area and a non-welding area. The terminals of the base are located in the welding area; and / or the thickness of the welding area is less than or equal to 0.8 mm, and the thickness of the non-welding area is less than or equal to 1.4 mm.
9. The current transformer according to claim 1, characterized in that: The central hole of the magnetic ring can be circular, square, or polygonal.
10. The current transformer according to claim 1, characterized in that: The terminal is a double-ended metal pin or a surface-mount pin.
11. The current transformer according to claim 1, characterized in that: The primary coil is made of a single metal conductor; or of multiple metal conductors connected in parallel; and / or the primary coil is made of one or more of copper, aluminum, silver, gold, or alloys, with an outer layer coated with an electroplated layer.