Miniature core for direct current transformer

Abstract

The utility model provides a kind of DC resistance micro mutual inductor iron core, it is related to the technical field of mutual inductor iron core, solve the problem of permeability drop in the air gap in the iron core of present time when using, including annular iron core main part, the annular iron core main part is made of nanocrystalline alloy strip spiral winding, its cross section is rectangular, the annular iron core main part circumferential direction non-equal interval distribution 4-6 air gaps, air gap spacing sequentially increases from start end to end, the annular iron core main part outer surface and air gap inner wall are all provided with insulating coating.This device makes effective permeability change more gently in whole working range, so that the output and input current of mutual inductor maintain good linear relationship.

Description

Technical Field

[0001] This utility model belongs to the technical field of current transformer cores, and more specifically, it relates to a DC-resistant miniature current transformer core. Background Technology

[0002] The transformer core is the core component of an instrument transformer, typically made of laminated silicon steel sheets with high magnetic permeability. It is used to efficiently conduct alternating magnetic fields, achieving voltage or current conversion. Its function is to couple the primary and secondary circuits, transmitting signals or energy through electromagnetic induction. The core design must consider hysteresis losses and eddy current losses; therefore, a thin-sheet laminated structure is used to reduce eddy currents.

[0003] Based on the above, the inventors discovered the following problem: Introducing an air gap into the magnetic circuit can significantly increase the magnetic reluctance. According to Ohm's law for magnetic circuits, under the same DC magnetomotive force (ampere-turns), the greater the magnetic reluctance, the smaller the generated DC magnetic flux. This is analogous to adding a resistor in series in a circuit, limiting the magnitude of the current. The air gap effectively "blocks" the DC component, keeping the operating point of the iron core within the linear region of the magnetization curve, thus ensuring its measurement accuracy for AC signals. Traditional methods may only use a single, large air gap. However, a single large air gap can cause severe divergence of magnetic field lines at the air gap (edge ​​effect), resulting in significant magnetic loss and leakage flux. It can also cause an excessive decrease in the overall permeability of the iron core, affecting sensitivity.

[0004] Therefore, in view of this, we have studied and improved the existing structure and its shortcomings, and provided a DC-resistant miniature transformer core in order to achieve a more practical value. Utility Model Content

[0005] To address the aforementioned technical problems, this utility model provides a DC-resistant miniature transformer core, which solves the problem of decreased magnetic permeability in current cores due to air gaps during use.

[0006] The purpose and effect of this utility model's anti-DC miniature transformer core are achieved by the following specific technical means: A DC-resistant miniature transformer core includes a toroidal core body, which is formed by spirally winding nanocrystalline alloy strip with a rectangular cross-section. The toroidal core body has 4-6 air gaps distributed non-equidistantly around its circumference, with the air gap spacing increasing sequentially from the starting end to the end. The outer surface of the toroidal core body and the inner wall of the air gaps are provided with an insulating coating.

[0007] Furthermore, the outer diameter of the ring-shaped iron core body is 10-15mm, the inner diameter is 6-8mm, the height is 5-10mm, and the ratio of the outer diameter to the height is in the range of 1.5-2.0.

[0008] Furthermore, the width of the air gap is 0.1-0.2 mm, the depth penetrates the radial section of the annular iron core body, and the thickness of the insulating coating on the inner wall of each air gap is 10%-20% thicker than the insulating coating on the outer surface of the annular iron core body.

[0009] Furthermore, the two ends of the annular iron core body are provided with annular grooves, the depth of which is 0.3-0.5mm and the width of which is 0.5-1mm, for embedding and fixing the winding skeleton.

[0010] Furthermore, the inner edge of the ring-shaped iron core body is chamfered, with a chamfer angle of 30°-45° and a chamfer width of 0.2-0.4mm.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The design of this invention matches the trend of the potential saturation degree of the iron core gradually increasing under DC bias. This increasing magnetic reluctance distribution can "compensate" or "correct" the inherent nonlinear magnetization curve of the iron core. The goal is to make the effective permeability of the entire iron core change more smoothly throughout the entire operating range after DC bias, thereby maintaining a good linear relationship between the output and input current of the transformer. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the core of a DC-resistant miniature transformer according to this utility model.

[0013] Figure 2 This is a three-dimensional schematic diagram of the core of a DC-resistant miniature transformer according to this utility model.

[0014] In the diagram, the correspondence between component names and drawing numbers is as follows: 1. Annular iron core body; 101. Strip; 102. Air gap; 103. Insulating coating; 2. Annular groove; 3. Chamfer. Detailed Implementation

[0015] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.

[0016] In the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0018] As attached Figure 1 To be continued Figure 2 As shown: This utility model provides a DC-resistant miniature transformer core, including a toroidal core body 1. The toroidal core body 1 is spirally wound from a nanocrystalline alloy strip 101. The strip 101 has a thickness of 18-22 μm and a rectangular cross-section. The toroidal core body 1 has 4-6 air gaps 102 distributed non-equidistantly in the circumferential direction, with the spacing increasing in increments of 0.05 mm, 0.08 mm, 0.12 mm, and 0.18 mm (adjacent spacing increases by 20%-50%). The spacing of the air gaps 102 increases sequentially from the starting end to the end end.

[0019] An insulating coating 103 is provided on the outer surface of the annular core body 1 and the inner wall of the air gap 102. The insulating coating 103 is an epoxy-modified silicone resin with a thickness of 20-30 μm.

[0020] The outer diameter of the annular iron core body 1 is 10-15mm, the inner diameter is 6-8mm, and the height is 5-10mm, with the ratio of the outer diameter to the height ranging from 1.5 to 2.0.

[0021] The air gap 102 has a width of 0.1-0.2 mm and a depth that penetrates the radial section of the annular iron core body 1. The thickness of the insulating coating 103 on the inner wall of each air gap 102 is 10%-20% thicker than the insulating coating 103 on the outer surface of the annular iron core body 1.

[0022] The annular core body 1 has annular grooves 2 on both ends. The annular grooves 2 have a depth of 0.3-0.5 mm and a width of 0.5-1 mm. They are used to embed and fix the winding skeleton. The annular grooves 2 are used to embed PBT plastic or glass fiber reinforced nylon winding skeletons. An interference fit (interference amount 0.05-0.15 mm) is adopted to ensure mechanical stability.

[0023] The inner edge of the annular iron core body 1 is provided with a chamfer 3, the chamfer 3 angle is 30°-45° and the chamfer 3 width is 0.2-0.4mm, which can avoid damage to the insulation layer of the enameled wire during winding.

[0024] In this application, conventional methods might only use a single, large air gap 102. However, a single large air gap 102 causes severe divergence of magnetic field lines at the air gap 102 (edge ​​effect), resulting in significant magnetic loss and leakage flux. It also causes an excessive decrease in the overall permeability of the core, affecting sensitivity. If the air gaps 102 are equidistantly distributed, the reluctance distribution of the entire magnetic circuit is uniform. However, in the presence of a DC bias, the saturation degree of different parts of the core is actually inconsistent. A uniform reluctance distribution cannot optimally compensate for this nonlinear saturation effect.

[0025] From the starting end (assuming it is the magnetomotive force starting point) to the end, the air gap 102 spacing increases, meaning that the increase in magnetic reluctance exhibits a non-linear, accelerating upward trend. This design cleverly matches the trend of the potential saturation degree of the iron core gradually increasing under DC bias.

[0026] This increasing magnetic reluctance distribution can "compensate" or "correct" the inherent nonlinear magnetization curve of the iron core. The goal is to make the effective permeability of the entire iron core change more smoothly throughout the entire operating range after DC is superimposed, thereby maintaining a good linear relationship between the output and input current of the transformer.

[0027] The embodiments of this utility model are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the utility model to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical applications of this utility model, and to enable those skilled in the art to understand this utility model and design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A DC-resistant miniature transformer core, comprising a toroidal core body (1), characterized in that: The annular core body (1) is formed by spirally winding strip (101) and has a rectangular cross-section. The annular core body (1) has 4-6 air gaps (102) distributed non-equidistantly in the circumferential direction. The spacing between the air gaps (102) increases sequentially from the starting end to the end end. The outer surface of the annular core body (1) and the inner wall of the air gaps (102) are provided with an insulating coating (103).

2. The DC-resistant miniature transformer core as described in claim 1, characterized in that: The outer diameter of the annular iron core body (1) is 10-15mm, the inner diameter is 6-8mm, the height is 5-10mm, and the ratio of the outer diameter to the height is in the range of 1.5-2.

0.

3. The DC-resistant miniature transformer core as described in claim 1, characterized in that: The width of the air gap (102) is 0.1-0.2 mm, and the depth penetrates the radial section of the annular iron core body (1). The thickness of the insulating coating (103) on the inner wall of each air gap (102) is 10%-20% thicker than the insulating coating (103) on the outer surface of the annular iron core body (1).

4. The DC-resistant miniature transformer core as described in claim 1, characterized in that: The annular iron core body (1) has annular grooves (2) on both ends. The annular grooves (2) are 0.3-0.5mm deep and 0.5-1mm wide, and are used to embed and fix the winding skeleton.

5. The DC-resistant miniature transformer core as described in claim 1, characterized in that: The inner hole edge of the annular iron core body (1) is provided with a chamfer (3), the chamfer (3) angle is 30°-45°, and the chamfer (3) width is 0.2-0.4mm.

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