A low parasitic capacitance differential mode inductor structure

Abstract

The utility model relates to the field of differential mode inductance, concretely to a low parasitic capacitance's differential mode inductance structure, including hollow skeleton, both ends of hollow skeleton all are fixedly connected with annular skeleton, two annular skeletons are symmetrically arranged, the fixedly connected with the magnetic core in hollow skeleton, be provided with the coil on hollow skeleton, be provided with the mounting assembly on hollow skeleton, be provided with the insulation assembly on hollow skeleton, the mounting assembly includes a plurality of first winding grooves, a plurality of first winding grooves are equidistantly arranged, the first winding groove is opened in the circumferential side of hollow skeleton, the second winding groove is opened in hollow skeleton, the second winding groove is linked with a plurality of first winding grooves, and the coil is located in the first winding groove and the second winding groove. Compared with the prior art, the mounting assembly and the insulation assembly are set up, the coil turn spacing is larger, the insulation pad forms the physical barrier between the winding layers, the interlayer conductor is directly contacted, and the interlayer capacitance is greatly reduced.

Description

Technical Field

[0001] This utility model relates to the field of differential mode inductors, specifically to a differential mode inductor structure with low parasitic capacitance. Background Technology

[0002] A differential-mode inductor is an inductor with high inductive reactance to differential-mode high-frequency interference, also known as a differential-mode choke coil. There are three types of magnetic core materials for differential-mode inductors. The iron-silicon-aluminum magnetic powder core has the lowest unit volume cost, making it the most suitable for manufacturing civilian differential-mode inductors. The price of iron-nickel 50 and iron-nickel-molybdenum magnetic powder cores is much higher than that of iron-silicon-aluminum magnetic powder cores, making them more suitable for military applications and some applications with high requirements for size and performance. Parasitic capacitance refers to the capacitive characteristics exhibited by capacitors, inductors, etc., under high-frequency conditions. Under high-frequency conditions, parasitic capacitance often easily leads to a decrease in the performance of electronic components, or even fails to meet performance requirements, especially near the pins, where parasitic capacitance is not negligible.

[0003] Chinese Patent No. CN206293260U discloses a differential mode inductor, including a manganese-zinc ferrite core, a high-temperature tape, a first tin-plated copper sheet, a second tin-plated copper sheet, and copper-clad steel tin-plated CP wires. The first tin-plated copper sheets are respectively disposed on the left and right sides of the front end of the high-temperature tape. The second tin-plated copper sheets are respectively disposed in the middle of the front end of the high-temperature tape and located between the two first tin-plated copper sheets. The front end of the first tin-plated copper sheets is provided with through holes. The copper-clad steel tin-plated CP wires are respectively vertically disposed in the through holes at the front end of the first tin-plated copper sheets.

[0004] Through the above methods, this utility model has the advantages of small size, light weight, and high cost performance. It can also effectively improve the impedance of the differential mode inductor, improve anti-interference performance, enhance the suppression of differential mode interference, and is convenient to use, saving materials and costs. However, a differential mode inductor in the prior art has the following drawbacks during operation:

[0005] (1) The differential mode inductor winding is surrounded by a magnetic core, and the magnetic core capacitance of the winding is large, resulting in high inter-turn distributed capacitance.

[0006] (2) The differential mode inductor has a small turn spacing and poor heat dissipation. Utility Model Content

[0007] The present invention aims to provide a differential mode inductor structure with low parasitic capacitance, mainly to solve the technical problem in the prior art where the winding is surrounded by a magnetic core, the winding core capacitance is large, resulting in high inter-turn distributed capacitance.

[0008] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0009] A differential-mode inductor structure with low parasitic capacitance includes a hollow frame, with annular frames fixedly connected to both ends of the hollow frame, the two annular frames being symmetrically arranged, a magnetic core fixedly connected inside the hollow frame, a coil disposed on the hollow frame, a mounting assembly disposed on the hollow frame, and an isolation assembly disposed on the hollow frame.

[0010] The working principle and beneficial effects of this utility model:

[0011] 1. Working principle: Differential mode current flows into the coil and generates a superimposed magnetic field in the magnetic core, producing a high differential mode inductive reactance that opposes the change of differential mode current. At the same time, the insulating pads, large turn spacing and insulating coating work together to minimize the parasitic capacitance between coil conductors and conductors to ground, achieving high performance and low parasitic capacitance differential mode filtering function.

[0012] 2. Beneficial effects:

[0013] (1) Existing technologies achieve small size, light weight and high cost performance by setting manganese-zinc ferrite core, high temperature tape, first tin-plated copper sheet, second tin-plated copper sheet and copper-clad steel tin-plated CP wire. However, the existing differential mode inductor winding is surrounded by the magnetic core, and the winding core capacitance is large, resulting in high inter-turn distributed capacitance. This solution sets up installation components and isolation components to make the coil turn spacing larger. The insulating pad forms a physical barrier between the winding layers, blocking the direct contact between the inter-layer conductors and greatly reducing the inter-layer capacitance.

[0014] (2) This solution sets up installation components to make the coil turn spacing larger. The larger turn spacing provides more air circulation space, which is conducive to coil heat dissipation and reduces temperature rise.

[0015] Preferably, the mounting assembly includes a plurality of first winding slots, which are equally spaced. The first winding slots are located on the periphery of the hollow frame. The hollow frame has second winding slots that are connected to the plurality of first winding slots. The coil is located within the first and second winding slots and is wound around the hollow frame. The coil has a large turn spacing. The equal spacing of the first winding slots forcibly fixes each turn or group of turns of the coil in a specific, spaced position. The second winding slots provide a channel for the coil to transition from one first winding slot to another adjacent first winding slot, ensuring the regularity of the winding. The spacing of the slots directly forces a larger physical distance between the coil turns, thereby minimizing the parasitic capacitance between the coil turns. This is the key to achieving a "low parasitic capacitance" inductance. The larger turn spacing provides more airflow space, which is beneficial for coil heat dissipation and reduces temperature rise. The winding slots fix the coil position, preventing the coil from shifting or loosening, and ensuring the stability of inductance parameters and mechanical reliability.

[0016] Preferably, each of the two annular frames has two snap-fit ​​slots. The two ends of the coil pass through the corresponding snap-fit ​​slots and extend to the outside. The snap-fit ​​slots provide precise exit positions and fixing points for the input and output ends of the coil, constrain the leads to prevent them from being directly pulled to the connection points with the coil body due to vibration or force, prevent the connection points from breaking or the coil from loosening due to lead swing or force, enhance mechanical strength and long-term reliability, fix the position of the leads, and make them easier to position and handle during subsequent circuit board installation or wiring.

[0017] Preferably, the insulating component includes a plurality of insulating pads, which are arranged at equal intervals. Each insulating pad has a fixing ring on both sides, and the fixing ring is fixedly connected to the periphery of the hollow frame. The pads form a physical barrier between the winding layers, blocking direct contact between the interlayer conductors and significantly reducing the interlayer capacitance.

[0018] Preferably, the insulating pad has a clearance groove that is connected to the second winding groove. The clearance groove ensures that the wire can pass through the pad axially while keeping the winding path undisturbed.

[0019] Preferably, the coil adopts a flat wire structure and an insulating coating is provided on the periphery of the coil. The flat wire has a more uniform surface curvature than the round wire. Combined with the insulating coating, the electric field distribution can be homogenized, reducing the risk of partial discharge. The flat wire is filled more tightly in the winding groove, increasing the inductance density. The insulating coating fills the microscopic defects on the surface of the conductor and eliminates potential corona discharge points.

[0020] Preferably, the insulating gasket is made of polytetrafluoroethylene (PTFE), which has one of the lowest dielectric constants among all engineering plastics and possesses flexibility and compression resilience. The low dielectric constant means that the capacitance formed by it as an insulating medium is very small, directly and significantly reducing the parasitic capacitance of the coil to ground through the retaining ring. The extremely high resistivity and extremely low dielectric loss maintain excellent insulation even at high temperatures and high frequencies, further reducing leakage current and dielectric loss. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of a differential-mode inductor structure with low parasitic capacitance according to this utility model patent.

[0022] Figure 2 This is a three-dimensional structural diagram of a coil with a low parasitic capacitance differential-mode inductor structure according to this utility model patent.

[0023] Figure 3 This is an exploded view of the annular frame region of a differential mode inductor structure with low parasitic capacitance according to this utility model patent.

[0024] Figure 4This is a three-dimensional structural diagram of the hollow skeleton region of a differential mode inductor structure with low parasitic capacitance according to this utility model patent.

[0025] Figure 5 This utility model patent discloses a differential mode inductor structure with low parasitic capacitance. Figure 4 Enlarged view of point A.

[0026] The reference numerals in the accompanying drawings include: 1. Hollow frame; 2. Ring frame; 3. Coil; 4. Magnetic core; 5. First winding groove; 6. Second winding groove; 7. Snap-fit ​​groove; 8. Retaining ring; 9. Insulating gasket; 10. Relief groove. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] like Figures 1-5As shown, a differential mode inductor structure with low parasitic capacitance includes a hollow frame 1, with two annular frames 2 fixedly connected to both ends of the hollow frame 1. The two annular frames 2 are symmetrically arranged. A magnetic core 4 is fixedly connected inside the hollow frame 1. A coil 3 is arranged on the hollow frame 1. The coil 3 adopts a flat wire structure and has an insulating coating on its periphery. A mounting assembly is arranged on the hollow frame 1. The mounting assembly includes several first winding slots 5, which are equally spaced and located on the periphery of the hollow frame 1. A second winding slot 6 is also provided on the hollow frame 1 and is connected to the several first winding slots 5. The coil 3 is located in the first winding slots 5 and the second winding slots 6. The coil 3 is wound with the hollow frame 1. The coil 3 has a large turn spacing. Two snap-fit ​​slots 7 are provided on each of the two annular frames 2. The two ends of the coil 3 pass through the corresponding snap-fit ​​slots 7 and extend to the outside. An isolation component is provided on the hollow frame 1. The isolation component includes several insulating pads 9, which are arranged at equal intervals. A fixing ring 8 is provided on both sides of the insulating pad 9, and the fixing ring 8 is fixedly connected to the periphery of the hollow frame 1. The insulating pad 9 has a clearance groove 10, which is connected to the second winding groove 6. The insulating pad 9 is made of polytetrafluoroethylene. The hollow frame 1 serves as the main support and basic framework of the entire inductor structure. It supports the magnetic core 4 and coil 3, and provides the foundation for the winding groove and the installation of the isolation components, providing mechanical strength and stability for the entire inductor. The first winding groove 5 and the second winding groove 6 on it precisely guide and fix the position of the coil 3, ensuring that the winding is neat and the spacing is controllable. The magnetic core 4 is fixed inside, protecting it from mechanical damage and maintaining its stable position. The hollow structure itself or its design may facilitate air circulation and assist in heat dissipation. The annular frame 2 is fixed at both ends of the hollow frame 1, mainly serving as the lead-out and fixing structure for the coil 3 terminals. The snap-fit ​​groove 7 on it is specifically used to guide and fix the lead-out end of the coil 3, preventing the lead wire from loosening or shifting, improving connection reliability. The symmetrical arrangement enhances the structural strength at both ends of the inductor and resists mechanical damage. Mechanical stress is used to spatially isolate the lead-out portion of coil 3 from the main winding area, helping to reduce the contribution of the lead-out wires to the winding capacitance. Magnetic core 4 provides the magnetic circuit, concentrating magnetic lines of force; it is the core component for inductor energy storage. Magnetic core 4 significantly improves permeability, allowing the required inductance value to be obtained within a smaller volume. Concentrating magnetic flux reduces leakage flux and improves inductor efficiency. Coil 3 generates a magnetic field through current, which is the main working element of the inductor. At high frequencies, the skin effect and proximity effect losses of flat wire are generally smaller than those of round wire of the same cross-sectional area, reducing copper losses, improving efficiency, and reducing heat generation. The insulating coating prevents inter-turn short circuits. The coating material is a low-dielectric-constant, high-insulation-strength coating material, such as polyimide or special polyester. It directly separates adjacent wires, significantly reducing parasitic capacitance. Increasing the distance between wires effectively reduces inter-turn and inter-layer capacitance. The larger gap allows for more airflow, aiding in heat dissipation of coil 3 and reducing temperature rise.In high-voltage applications, a larger spacing reduces the electric field strength between conductors, decreases the possibility of partial discharge, improves reliability, ensures precise positioning of coil 3, and maintains the designed turn spacing and shape. The first winding slot 5 and the second winding slot 6 provide a precise winding path and fixed position for coil 3. The first winding slot 5 is equally spaced, forcing coil 3 to maintain a precise and uniform large spacing during winding, providing physical assurance for the "larger turn spacing" design intent, ensuring that the designed distance is maintained between each turn, and minimizing inter-turn capacitance. The second winding slot 6 is connected to the first winding slot 5, allowing coil 3 to transition from one slot to another, forming a continuous winding, while maintaining the coil 3's positioning in the transition area. The slot structure firmly restricts coil 3 in the predetermined position, preventing displacement of coil 3 due to vibration or thermal expansion and contraction, avoiding accidental reduction in turn spacing or short circuits. Insulating pads 9 and fixing rings 8 provide insulation between the winding layers of coil 3. An additional physical isolation barrier with a low dielectric constant is provided. Polytetrafluoroethylene (PTFE) is one of the solid materials with the lowest known dielectric constant, which is another core design point for achieving "low parasitic capacitance" in this structure. The dielectric constant of the interlayer capacitance formed by PTFE as an insulator is much lower than that of air or ordinary insulating materials. Therefore, even at the same distance, it can significantly reduce interlayer capacitance, which is more effective than simply increasing the air gap. PTFE is heat-resistant, not prone to aging, has stable and reliable performance, and has extremely low dielectric loss at high frequencies. The clearance slot 10 allows the wires in the second winding slot 6 to pass through, ensuring that the gasket will not compress or damage this part of the coil 3. At the same time, the gasket body can still effectively isolate other parts between the layers. The retaining ring 8 firmly clamps and positions the insulating gasket 9 in the predetermined position of the hollow frame 1, ensuring that the position of the isolation layer is accurate and stable, and will not move or fall off, ensuring that the physical isolation gap provided by the insulating gasket 9 remains constant throughout the entire inductor's lifespan.

[0029] As can be seen from the above, the specific embodiments of this utility model are as follows:

[0030] Differential mode current flows into coil 3 from one end, passes through the first winding slot 5 and the second winding slot 6 wound on the hollow frame 1, and finally flows out from the other end of coil 3. When the differential mode current flows through coil 3, since the current direction is always consistent in adjacent turns, the magnetic field generated by the current is superimposed in the magnetic core 4. The magnetic core 4 has high permeability, which can concentrate and enhance this magnetic field. According to Faraday's law of electromagnetic induction, this changing magnetic field will induce an electromotive force that opposes the change of current in coil 3, i.e., inductive reactance. The presence of the magnetic core 4 significantly increases the value of this inductive reactance. In this process, the insulating pad 9, the large turn spacing and the insulating coating work together to minimize the parasitic capacitance between conductors and between conductors and ground of coil 3.

[0031] The above descriptions are merely embodiments of this utility model, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A differential-mode inductor structure with low parasitic capacitance, comprising a hollow frame (1), characterized in that: Both ends of the hollow skeleton (1) are fixedly connected to annular skeletons (2), the two annular skeletons (2) are symmetrically arranged, a magnetic core (4) is fixedly connected inside the hollow skeleton (1), a coil (3) is provided on the hollow skeleton (1), an installation component is provided on the hollow skeleton (1), and an isolation component is provided on the hollow skeleton (1).

2. The differential-mode inductor structure with low parasitic capacitance according to claim 1, characterized in that: The mounting assembly includes several first winding slots (5), which are arranged at equal intervals. The first winding slots (5) are opened on the periphery of the hollow frame (1). The hollow frame (1) is provided with second winding slots (6), which are connected to several first winding slots (5). The coil (3) is located in the first winding slots (5) and the second winding slots (6), and the coil (3) is wound around the hollow frame (1).

3. The differential-mode inductor structure with low parasitic capacitance according to claim 1, characterized in that: Two snap-fit ​​slots (7) are provided on each of the two ring skeletons (2), and the two ends of the coil (3) pass through the corresponding snap-fit ​​slots (7) and extend to the outside.

4. The differential-mode inductor structure with low parasitic capacitance according to claim 3, characterized in that: The insulating component includes a plurality of insulating pads (9), which are arranged at equal intervals. Each insulating pad (9) has a fixing ring (8) on both sides, and the fixing ring (8) is fixedly connected to the periphery of the hollow frame (1).

5. The differential-mode inductor structure with low parasitic capacitance according to claim 4, characterized in that: The insulating pad (9) has a relief groove (10) which is connected to the second winding groove (6).

6. The differential-mode inductor structure with low parasitic capacitance according to claim 1, characterized in that: The coil (3) adopts a flat wire structure, and an insulating coating is provided on the periphery of the coil (3).

7. The differential-mode inductor structure with low parasitic capacitance according to claim 4, characterized in that: The insulating pad (9) is made of polytetrafluoroethylene.

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