Fixture design method for improving high-frequency impedance of differential mode filter inductor

Abstract

The invention discloses a clamp design method for improving the high-frequency impedance of a differential-mode filter inductor, and the method comprises the steps: determining the number of turns of a winding of the differential-mode filter inductor, carrying out the winding on a magnetic core to form a preliminary inductor, and obtaining the actual parasitic capacitance value of the preliminary inductor; therefore, the target reduction amount of the parasitic capacitance of the differential-mode filter inductor is obtained; obtaining the thickness of the clamp according to the target reduction amount of the parasitic capacitance of the differential mode filter inductor; and the clamp is designed according to the thickness of the clamp and the number of turns of windings. The stray capacitance of the inductor is controlled through the thickness of the clamp and the number of turns of the windings, and the impedance performance of the inductor in a high-frequency environment is effectively improved. The impedance improvement not only enhances the filtering effect of the inductor, but also remarkably improves the performance stability of the inductor in high-frequency application.

Description

Technical Field

[0001] The present invention relates to the technical field of high-pressure valve cold sensor systems, and in particular to a fixture design method for improving the high-frequency impedance of a differential mode filter inductor. Background Art

[0002] With the rapid development of the global economy and the rise of emerging industries, the demand for electricity continues to grow. As a key solution for achieving long-distance, efficient and low-loss power transmission, ultra-high voltage direct current (UHVDC) technology not only meets the national energy structure optimization and green development strategic goals, but also significantly improves the stability and reliability of the power grid. The converter valve in the UHVDC system is a core device, and its operating stability is directly related to the safety of the power system. Under high power and long-term operation conditions, the converter valve will generate a lot of heat, which may cause the equipment to overheat, affect normal operation, and even cause system failure in extreme cases. Therefore, the cooling system of the converter valve must be highly reliable, equipped with sensors that monitor the circulating water temperature and flow in real time, and feed the data back to the control system to ensure safe operation.

[0003] At the same time, the power electronic equipment centrally arranged in the converter station will generate strong electromagnetic interference during operation, especially high-frequency switching current. These interference signals may cause differential mode interference through the current loop, affecting the stability of the control system. As the sensor design tends to be miniaturized, the sensitivity of its internal circuit to differential mode interference has also increased. In order to effectively suppress differential mode interference, differential mode inductors are usually used in filters. However, the presence of parasitic capacitance may cause impedance shift caused by high-frequency signals, affecting the filtering effect. Therefore, precise control of high-frequency parasitic capacitance is particularly critical for optimizing filter performance, meeting electromagnetic compatibility (EMC) standards, and without increasing the weight and volume of the equipment. Magnetic powder cores, as an important magnetic material, are widely used in the field of power electronics, especially in differential mode inductors. Due to the low magnetic permeability and low dielectric constant of magnetic powder cores, the existing high-frequency parasitic capacitance suppression methods have limited effect in their applications.

[0004] In high-frequency environments, the parasitic capacitance of the inductor (including the inter-turn capacitance Ctt and the capacitance between the turns and the core Ctc) has a significant impact on its performance. In order to improve the high-frequency impedance and effectively reduce the parasitic capacitance value, a variety of methods are used in engineering practice. First, by adding additional capacitors next to the inductor, the high-frequency response of the overall inductor can be enhanced, thereby reducing the negative impact of parasitic capacitance on performance. This method improves the impedance characteristics of the inductor under high-frequency conditions by increasing the equivalent capacitance of the inductor. In addition, the use of plastic bobbins is a common technical means. By increasing the distance between the windings and between the windings and the core, the parasitic capacitance Ctc between the turns and the core can be effectively reduced. This not only helps to reduce capacitive coupling, but also improves the stability and efficiency of the inductor at high frequencies. The insulation properties of the plastic bobbin can further reduce the electromagnetic interference caused by conductive materials and improve the overall performance of the inductor. In terms of the optimization of the winding method, the use of different winding technologies can significantly improve the high-frequency performance of the inductor. For example, refined winding arrangement and compact winding structure design can reduce the generation of parasitic capacitance while improving the self-inductance and leakage inductance characteristics of the inductor. By optimizing the winding method, not only can Ctt and Ctc be reduced, but also the quality factor of the inductor can be improved, thereby enhancing its performance in high-frequency applications. In addition, using aluminum foil to shield the winding is also an effective technical means. Aluminum foil shielding can increase the coupling between the winding and the ground, reduce the electromagnetic coupling through the component, and thus reduce differential mode interference and common mode interference. This shielding method not only helps to improve the anti-interference ability of the inductor, but also improves its stability and reliability in complex electromagnetic environments.

[0005] However, these methods are mainly applicable to magnetic core materials to which the perfect electric conductor (PEC) assumption can be applied. For magnetic core materials with low conductivity or complex structures, the effectiveness of these methods may be limited. The EMI noise reduction effect of differential mode filter inductors is low, especially in high-frequency applications. The performance stability is poor, resulting in the inductor's anti-electromagnetic interference ability unable to ensure its stable operation in complex electromagnetic environments. Summary of the invention

[0006] The invention discloses a fixture design method for improving the high-frequency impedance of a differential mode filter inductor, so as to overcome the above technical problems.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A fixture design method for improving the high-frequency impedance of a differential mode filter inductor comprises the following steps:

[0009] S1: Determine the number of winding turns of the differential mode filter inductor according to the size of the magnetic core;

[0010] S2: According to the number of turns of the winding of the differential mode filter inductor, winding is performed on the magnetic core to form a preliminary inductor to obtain the preliminary actual parasitic capacitance value of the inductor; and then based on the parasitic capacitance value corresponding to the set target broadband impedance value, the parasitic capacitance target reduction amount of the differential mode filter inductor is obtained;

[0011] S3: obtaining an optimal distance from the winding to the magnetic core, that is, a fixture thickness, according to a target reduction amount of the parasitic capacitance of the differential mode filter inductor;

[0012] S4: Determine the number of slots on the fixture for winding according to the number of turns of the winding of the differential mode filter inductor, and model the fixture according to the number of slots and the thickness of the fixture to complete the design of the fixture.

[0013] Furthermore, in S1, the formula used to determine the number of winding turns of the differential mode filter inductor is as follows:

[0014]

[0015] Where: Z is the impedance value; L is the inductance value; j is the Laplace operator; ω is the angular frequency; μ is the magnetic permeability of the magnetic core; h c is the thickness of the magnetic core; R o is the outer radius of the core; R in is the inner radius of the magnetic core; N is the number of turns of the inductor winding;

[0016] Furthermore, in S2, the formula used to obtain the target reduction amount of the parasitic capacitance of the differential mode filter inductor is as follows:

[0017] The target reduction amount of the parasitic capacitance of the differential mode filter inductor = the actual parasitic capacitance value of the preliminary inductor - the parasitic capacitance value corresponding to the set target broadband impedance value.

[0018] Furthermore, in S3, the formula used to obtain the optimal distance from the winding to the magnetic core is as follows:

[0019] C=ε 0 ε e S / x i / ε ri

[0020] Where: C represents the target reduction of parasitic capacitance of differential mode filter inductor; ε 0 represents the dielectric constant of vacuum; ε e represents the equivalent dielectric constant; S represents the area corresponding to the winding and the core; x i Indicates the optimal distance from the winding to the core, that is, the thickness of the fixture; ε ri represents the relative dielectric constant of the fixture;

[0021] in,

[0022]

[0023] Where: d all Indicates the distance between the center of the winding and the center plane of the magnetic core; d mi Indicates the thickness of the medium; ε mi represents the dielectric constant of the medium; i represents the index of the medium;

[0024] Further, in S4, the fixture includes a supporting inner ring, a supporting outer ring, and a plurality of connecting rods;

[0025] The supporting inner ring and the supporting outer ring are coaxially arranged;

[0026] One end of the connecting rod is fixedly connected to the outer wall surface of the supporting inner ring;

[0027] The other end of the connecting rod is fixedly connected to the inner wall surface of the supporting outer ring;

[0028] N first grooves are evenly distributed on the top surface of the supporting inner ring; the center plane of the first groove passes through the axis of the supporting inner ring; wherein N is the number of turns of the inductor winding;

[0029] N second grooves corresponding to the first grooves are evenly distributed on the top surface of the supporting outer ring;

[0030] The distance between the bottom of the first groove and the top surface of the supporting inner ring is equal to the distance between the bottom of the second groove and the top surface of the supporting outer ring;

[0031] The distance between the bottom of the first groove and the side of the connecting rod away from the top surface of the supporting inner ring is the thickness of the clamp;

[0032] The outer diameter of the supporting inner ring is equal to the inner diameter of the magnetic core;

[0033] The inner diameter of the supporting outer ring is equal to the outer diameter of the magnetic core.

[0034] Furthermore, after S4, it further includes: using 3D printing technology to print the modeled fixture, so as to coaxially install the magnetic core between two fixtures according to the printed fixture and perform winding to form an inductor, so as to obtain the broadband impedance of the inductor and verify the fixture performance;

[0035] The two end surfaces of the magnetic core are respectively in contact with the surfaces of the connecting rods of the two clamps away from the top surface of the supporting inner ring.

[0036] Furthermore, the material selected by the 3D printing technology is ABS, PLA or nylon.

[0037] Beneficial effect: A fixture design method for improving the high-frequency impedance of a differential mode filter inductor of the present invention determines the number of winding turns of the differential mode filter inductor, forms a preliminary inductor by winding on a magnetic core, and obtains the actual parasitic capacitance value of the preliminary inductor; thereby obtaining the parasitic capacitance target reduction of the differential mode filter inductor; then, according to the parasitic capacitance target reduction of the differential mode filter inductor, the fixture thickness is obtained; and then, according to the fixture thickness and the number of winding turns, the fixture design is completed. The parasitic capacitance of the inductor (including the inter-turn capacitance Ctt and the capacitance Ctc between the turn and the magnetic core) is controlled by the thickness and the number of winding turns of the fixture designed by the present invention, which effectively improves the impedance performance of the inductor in a high-frequency environment. This impedance improvement not only enhances the filtering effect of the inductor, but also significantly improves its performance stability in high-frequency applications. The use of the fixture of the present invention to design the inductor can significantly improve the high-frequency performance and electromagnetic compatibility of the inductor equipment, improve the anti-electromagnetic interference ability of the inductor, and ensure its stable operation in a complex electromagnetic environment. The improvement of high-frequency impedance helps to better filter out unwanted high-frequency noise, meet strict electromagnetic compatibility standards, and improve the overall reliability and safety of the equipment. At the same time, it can effectively reduce the design cycle, reduce the design cost, and significantly improve the design efficiency, and can be widely used in the design and optimization of differential mode EMI filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 This is a flow chart of the method for designing a fixture for improving the high-frequency impedance of a differential mode filter inductor according to the present invention;

[0040] Figure 2 It is a schematic diagram of the mechanism of a magnetic powder core capacitor without a fixture in an embodiment of the present invention;

[0041] Figure 3 It is a schematic diagram of the mechanism of a magnetic powder core capacitor with a clamp in an embodiment of the present invention;

[0042] Figure 4 A flow chart of 3D printing fixture design in an embodiment of the present invention;

[0043] Figure 5 Schematic diagram of a 3D printing fixture in an embodiment of the present invention;

[0044] Figure 6It is a schematic diagram of assembling a 3D printing fixture and a magnetic powder core in an embodiment of the present invention;

[0045] Figure 7 is a physical picture of an inductor with a clamp in an embodiment of the present invention;

[0046] Figure 8 It is a schematic diagram of impedance comparison between an inductor without a clamp and an inductor with a clamp in an embodiment of the present invention.

[0047] Among them, 1. support inner ring; 11. first slot; 2. support outer ring; 21. second slot; 3. connecting rod; 4. magnetic core. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] This embodiment introduces a fixture design method for improving the high-frequency impedance of a differential mode filter inductor. Figure 1 As shown, the following steps are included:

[0050] S1: Determine the number of winding turns of the differential mode filter inductor according to the size of the magnetic core;

[0051] Preferably, the formula used to determine the number of winding turns of the differential mode filter inductor is as follows:

[0052]

[0053] Where: Z is the impedance value; L is the inductance value; j is the Laplace operator; ω is the angular frequency; μ is the magnetic permeability of the magnetic core; h c is the thickness of the magnetic core; R o is the outer radius of the core; R in is the inner radius of the magnetic core; N is the number of turns of the inductor winding;

[0054] Specifically, this embodiment determines the geometric parameters of the inductor according to the performance requirements of the inductor. Among them, according to the differential mode EMI characteristics of the target system, the broadband impedance value required to suppress the differential mode EMI, that is, the corresponding inductance value, is specifically determined. Then, according to the size of the magnetic core, the number of winding turns of the differential mode filter inductor is determined.

[0055] S2: According to the number of turns of the winding of the differential mode filter inductor, winding is performed on the magnetic core to form a preliminary inductor to obtain the preliminary actual parasitic capacitance value of the inductor; and then based on the parasitic capacitance value corresponding to the set target broadband impedance value, the parasitic capacitance target reduction amount of the differential mode filter inductor is obtained;

[0056] Preferably, the formula used to obtain the target reduction amount of the parasitic capacitance of the differential mode filter inductor is as follows:

[0057] The target reduction amount of the parasitic capacitance of the differential mode filter inductor = the actual parasitic capacitance value of the preliminary inductor - the parasitic capacitance value corresponding to the set target broadband impedance value.

[0058] In this embodiment, after determining the number of winding turns of the differential mode filter inductor, winding is performed on the magnetic core to obtain a preliminary inductor, and then the preliminary inductor is tested by an impedance analyzer to obtain the actual broadband impedance value. After obtaining the impedance, the broadband impedance is fitted by an LC parallel circuit to obtain a preliminary actual parasitic capacitance value of the inductor, wherein the method for obtaining the preliminary actual parasitic capacitance value of the inductor is a conventional technology in the field and is not described in detail here. Specifically, an LC parallel circuit is constructed; then the inductance value used when determining the number of winding turns of the differential mode filter inductor is used, and the capacitance value is debugged by an impedance analyzer. When the capacitance value makes the capacitance segment impedance of the LC parallel circuit coincide with the actual broadband impedance value, the capacitance value obtained is the parasitic capacitance value. Subsequently, the parasitic capacitance value corresponding to the set target broadband impedance value is subtracted from the actual parasitic capacitance value of the inductor, and the parasitic capacitance target reduction amount can be obtained.

[0059] S3: obtaining an optimal distance from the winding to the magnetic core, that is, a fixture thickness, according to a target reduction amount of the parasitic capacitance of the differential mode filter inductor;

[0060] Preferably, the formula used to obtain the optimal distance from the winding to the magnetic core is as follows:

[0061] C=ε 0 ε e S / x i / ε ri

[0062] Where: C represents the target reduction of parasitic capacitance of differential mode filter inductor; ε 0 represents the dielectric constant of vacuum; ε e represents the equivalent dielectric constant; S represents the area corresponding to the winding and the core; x i Indicates the optimal distance from the winding to the core, that is, the thickness of the fixture; ε ri represents the relative dielectric constant of the fixture;

[0063] in,

[0064]

[0065] Where: d all Indicates the distance between the center of the winding and the center plane of the magnetic core; d mi Indicates the thickness of the medium; ε mi represents the dielectric constant of the medium; i represents the index of the medium;

[0066] Specifically, ε e is the equivalent dielectric constant of the fixture and air. The medium includes air, fixture and magnetic core.

[0067] S4: Modeling the fixture according to the number of winding turns of the differential mode filter inductor and the thickness of the fixture to complete the design of the fixture.

[0068] Preferably, the fixture comprises a supporting inner ring 1, a supporting outer ring 2, and a plurality of connecting rods 3;

[0069] The supporting inner ring 1 and the supporting outer ring 2 are coaxially arranged;

[0070] One end of the connecting rod 3 is fixedly connected to the outer wall surface of the supporting inner ring 1;

[0071] The other end of the connecting rod 3 is fixedly connected to the inner wall surface of the supporting outer ring 2;

[0072] N first grooves 11 are evenly distributed on the top surface of the supporting inner ring 1; the center plane of the first groove 11 passes through the axis of the supporting inner ring 1; wherein N is the number of turns of the inductor winding;

[0073] N second grooves 21 corresponding to the first grooves 11 are evenly distributed on the top surface of the supporting outer ring 2;

[0074] The distance between the bottom of the first groove 11 and the top surface of the support inner ring 1 is equal to the distance between the bottom of the second groove 21 and the top surface of the support outer ring 2;

[0075] The distance between the bottom of the first groove 11 and the side of the connecting rod 3 away from the top surface of the supporting inner ring 1 is the thickness of the fixture;

[0076] The outer diameter of the supporting inner ring 1 is equal to the inner diameter of the magnetic core;

[0077] The inner diameter of the supporting outer ring 2 is equal to the outer diameter of the magnetic core.

[0078] Specifically, in this embodiment, the geometric design of the fixture is divided into two parts, which are used to determine the number of slots for the winding and the thickness. After the number of slots and the thickness of the fixture are determined, computer-aided design software (such as Solidowrks) is used for three-dimensional modeling to draw the detailed geometric structure of the fixture to ensure the precise positioning of all slots and supporting components. After modeling, the fixture is 3D printed. Therefore, in the three-dimensional modeling process, it is necessary to consider the technical limitations of 3D printing, such as the minimum printing size, layer thickness, and support structure design, in order to ensure the success rate of the fixture during the printing process and the quality of the finished product. To this end, most of the fixture designed in this embodiment is hollowed out, leaving only the necessary supports, such as Figure 5 , Figure 6 and Figure 7 As shown, the 3D printed fixture and its position on the magnetic powder core can be clearly seen. The number of connecting rods 3 is generally half of the number of slots, and the thickness is also half of the thickness of the fixture. The number is based on ensuring that the inner and outer rings of the fixture are firmly supported, and the specific design is carried out according to the actual situation.

[0079] In addition, it is also necessary to further reduce the influence of the dielectric constant of the fixture itself on the parasitic capacitance. In order to adapt to the magnetic cores of different materials and reduce the high-frequency parasitic capacitance, this embodiment selects 3D printing materials with high strength, high temperature resistance and good insulation performance, such as ABS, PLA or nylon, according to the working environment of the inductor and the mechanical requirements of the fixture. After completing the material selection, the designed fixture model is printed out using 3D printing technology. During the printing process, it is necessary to optimize the printing parameters, such as printing speed, layer thickness, filling density and the use of support structure, to ensure the accuracy and surface quality of the fixture. After printing is completed, the fixture is subjected to necessary post-processing, such as removing the support structure, polishing the surface and checking the dimensional accuracy to ensure that it fully meets the design requirements. This fixture can effectively reduce Ctc by accurately adjusting the distance between the windings and between the windings and the magnetic core, thereby suppressing the high-frequency parasitic capacitance and improving the high-frequency performance of the inductor. Compared with traditional methods, 3D printing technology provides higher design flexibility and adaptability, and is suitable for various magnetic materials.

[0080] Preferably, after S4, the method further includes: using 3D printing technology to print the modeled fixture, and according to the printed fixture, coaxially installing the magnetic core between two fixtures and performing winding to form an inductor, so as to obtain the broadband impedance of the inductor and verify the fixture performance;

[0081] The two end surfaces of the magnetic core are respectively in contact with the surfaces of the connecting rods 3 of the two clamps away from the top surface of the supporting inner ring 1 .

[0082] Preferably, the material selected by 3D printing technology is ABS, PLA or nylon.

[0083] In this embodiment, the printed fixture is applied to the actual inductor winding arrangement, and the broadband impedance is measured by an impedance analyzer to perform a high-frequency performance test to determine whether the inductor meets the target requirements in the high-frequency capacitance section (i.e., 150kHz to 30MHz), and to verify the effectiveness of the fixture in reducing parasitic capacitance and improving high-frequency impedance. Specifically, when the impedance of the inductor minus the target impedance is less than 0, the inductor after the fixture winding does not meet the requirements, and the thickness of the fixture needs to be recalculated, and the fixture needs to be redesigned and printed to optimize the fixture performance.

[0084] Through the method of this embodiment, a magnetic powder core inductor design that can adapt to different sizes and specifications is finally formed, and the high-frequency performance and electromagnetic compatibility (EMC) of the inductor can be significantly improved, providing solid technical support and practical basis for the widespread application of magnetic powder core materials in high-frequency inductors.

[0085] Specifically, through the fixture design method of this embodiment, a detachable fixture based on 3D printing is finally obtained. The fixture optimizes the distribution path of the electric field lines by accurately adjusting the distance between the winding and the magnetic core and between the windings, thereby effectively reducing the parasitic capacitance Ctc and the static capacitance Ccs of the magnetic core. Specifically, 3D printing technology makes the design of the fixture highly flexible and customizable, and the fixture can be quickly adjusted according to different inductor structure requirements. Among them, the electric field lines generated by the windings first enter the air and then enter the magnetic core. Obviously, the path of the electric field lines in the magnetic core is basically determined, and the only variable is the path of the electric field lines in the air, such as Figure 2 and Figure 3 As shown. This path change directly determines the value of Ctc, which is the capacitance in series with the static capacitance Ccs of the magnetic core, resulting in a reduction in the equivalent parasitic capacitance EPC. Therefore, the high-frequency impedance and performance of the magnetic powder core are improved. This design not only simplifies the manufacturing process, but also improves the accuracy of adjustment and ensures effective control of parasitic capacitance. The design process of the 3D printing fixture for the magnetic powder core based on this embodiment is as follows: Figure 4 As shown in the figure, by precisely controlling the distance between the winding and the magnetic core, the parasitic capacitance is reduced and the high-frequency impedance of the inductor is effectively improved:

[0086] (1) Use 3D printing technology: Use 3D printed detachable fixtures to increase the distance between the winding and the magnetic core. By optimizing the number of turns of the inductor winding and the thickness of the fixture, the parasitic capacitance is controlled. This not only effectively reduces the parasitic capacitance Ctc between the turns and the magnetic core, but also improves the stability of the inductor under high-frequency conditions. In this way, the inductor can better resist electromagnetic interference and further improve its high-frequency impedance. It effectively improves the impedance performance of the inductor in a high-frequency environment and significantly improves its filtering performance and anti-electromagnetic interference capability.

[0087] (2) Optimize winding structure: Improve the winding method by adjusting the thickness and number of slots of the fixture, optimize the arrangement and density of the winding, and in contrast to the high conductivity and high dielectric constant magnetic cores that require tightly wound windings to reduce parasitic capacitance, the differential mode EMI filter inductor, i.e., the magnetic powder core, requires loose windings to effectively reduce parasitic capacitance. Through the design of this embodiment, the high-frequency impedance of the inductor can be improved without increasing the extra volume.

[0088] Figure 8 The schematic diagram of impedance comparison between the inductor without the clamp and the inductor with the clamp of the present embodiment is shown. It can be seen from the figure that in the low frequency band, the impedance of the inductor without the clamp is almost the same as the impedance of the inductor with the clamp, while in the high frequency band, the maximum impedance value of the inductor with the clamp is higher than the maximum impedance value of the inductor without the clamp. It can be seen that the impedance performance of the inductor with the clamp of the present embodiment is better in a high frequency environment, which has outstanding advantages in improving the high frequency performance and electromagnetic compatibility of the inductor equipment, improving the anti-electromagnetic interference ability of the inductor, and ensuring the stable operation of the inductor in a complex electromagnetic environment.

[0089] This embodiment not only simplifies the manufacturing and optimization process, reduces design cost and time, but also expands the material application range of high-frequency inductor design, and has important theoretical significance and wide practical application value. Designers can quickly obtain accurate inductor performance data, optimize the structure of the inductor, and improve the EMI noise reduction effect of the filter without conducting a large number of experiments. The implementation of this method can not only improve the high-frequency performance and electromagnetic compatibility of the equipment, but also has high economy and practical application value, and can be widely used in the design and optimization of differential mode EMI filters.

[0090] At the same time, this embodiment breaks through the limitation that the traditional high-frequency impedance enhancement technology is mainly applicable to nanocrystalline and MnZn magnetic core materials, and successfully expands the application to magnetic powder core materials. Especially in differential-mode EMI filter inductors, it greatly broadens the material selection range of high-frequency inductor design and improves the flexibility and extensiveness of its application. By considering the actual geometric structure and electric field behavior of the inductor, this embodiment can provide more accurate leakage inductance, parasitic capacitance, etc. through the design of the fixture, which provides a reliable basis for the design and optimization of differential-mode EMI filter inductors, and can effectively improve the high-frequency performance and filtering effect of the inductor.

[0091] The detachable fixture based on 3D printing adopted in this embodiment enables the structural parameters of the inductor to be quickly adjusted and optimized according to specific needs, avoiding complex simulation solutions, saving design costs, and providing a more direct solution for the optimization of differential mode EMI filter inductors. Designers can flexibly adjust the winding spacing and the distance between the winding and the magnetic core according to different working environments and performance requirements to ensure that the inductor can achieve optimal performance under various high-frequency conditions.

[0092] In summary, this embodiment improves the anti-electromagnetic interference capability of the inductor and ensures its stable operation in a complex electromagnetic environment. The improvement of high-frequency impedance helps to better filter out unwanted high-frequency noise, meet strict electromagnetic compatibility standards, and improve the overall reliability and safety of the device.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fixture design method for improving the high-frequency impedance of a differential mode filter inductor, characterized in that: The steps include: S1: Determine the number of winding turns of the differential mode filter inductor according to the size of the magnetic core; S2: According to the number of turns of the winding of the differential mode filter inductor, winding is performed on the magnetic core to form a preliminary inductor to obtain the preliminary actual parasitic capacitance value of the inductor; and then based on the parasitic capacitance value corresponding to the set target broadband impedance value, the parasitic capacitance target reduction amount of the differential mode filter inductor is obtained; S3: obtaining an optimal distance from the winding to the magnetic core, that is, a fixture thickness, according to a target reduction amount of the parasitic capacitance of the differential mode filter inductor; S4: Determine the number of slots on the fixture for winding according to the number of turns of the winding of the differential mode filter inductor, and model the fixture according to the number of slots and the thickness of the fixture to complete the design of the fixture.

2. A fixture design method for improving high-frequency impedance of differential mode filter inductors according to claim 1, characterized in that: In S1, the formula used to determine the number of winding turns of the differential mode filter inductor is as follows: Where: Z is the impedance value; L is the inductance value; j is the Laplace operator; ω is the angular frequency; μ is the magnetic permeability of the core; h c is the thickness of the magnetic core; R o is the outer radius of the core; R in is the inner radius of the core; N is the number of turns of the inductor winding.

3. A fixture design method for improving high-frequency impedance of differential mode filter inductors according to claim 1, characterized in that: In S2, the formula used to obtain the target reduction amount of the parasitic capacitance of the differential mode filter inductor is as follows: The target reduction amount of the parasitic capacitance of the differential mode filter inductor = the actual parasitic capacitance value of the preliminary inductor - the parasitic capacitance value corresponding to the set target broadband impedance value.

4. A fixture design method for improving high-frequency impedance of differential mode filter inductors according to claim 1, characterized in that: In S3, the formula used to obtain the optimal distance from the winding to the magnetic core is as follows: C=ε0ε e S / x i / e ri Where: C represents the target reduction of the parasitic capacitance of the differential mode filter inductor; ε0 represents the vacuum dielectric constant; ε e represents the equivalent dielectric constant; S represents the area corresponding to the winding and the core; x i Indicates the optimal distance from the winding to the core, that is, the thickness of the fixture; ε ri represents the relative dielectric constant of the fixture; in, Where: d all Indicates the distance between the center of the winding and the center plane of the magnetic core; d mi Indicates the thickness of the medium; ε mi represents the dielectric constant of the medium; i represents the index of the medium.

5. A method for designing a fixture for improving high-frequency impedance of a differential mode filter inductor according to claim 1, characterized in that: In S4, the clamp comprises a supporting inner ring (1), a supporting outer ring (2), and a plurality of connecting rods (3); The supporting inner ring (1) and the supporting outer ring (2) are coaxially arranged; One end of the connecting rod (3) is fixedly connected to the outer wall surface of the supporting inner ring (1); The other end of the connecting rod (3) is fixedly connected to the inner wall surface of the supporting outer ring (2); N first grooves (11) are evenly distributed on the top surface of the supporting inner ring (1); the center plane of the first groove (11) passes through the axis of the supporting inner ring (1); wherein N is the number of turns of the inductor winding; N second grooves (21) corresponding to the first grooves (11) are evenly distributed on the top surface of the supporting outer ring (2); The distance between the bottom of the first groove (11) and the top surface of the supporting inner ring (1) is equal to the distance between the second groove (21) and the top surface of the supporting outer ring (2); The distance between the bottom of the first groove (11) and the side of the connecting rod (3) away from the top surface of the supporting inner ring (1) is the thickness of the clamp; The outer diameter of the supporting inner ring (1) is equal to the inner diameter of the magnetic core (4); The inner diameter of the supporting outer ring (2) is equal to the outer diameter of the magnetic core (4).

6. A fixture design method for improving high-frequency impedance of differential mode filter inductors according to claim 1, characterized in that: After S4, the method further includes: using 3D printing technology to print the modeled fixture, and according to the printed fixture, coaxially installing the magnetic core between two fixtures and performing winding to form an inductor, so as to obtain the broadband impedance of the inductor and verify the fixture performance; The two end faces of the magnetic core (4) are respectively in contact with the surfaces of the connecting rods (3) of the two clamps that are away from the top surface of the supporting inner ring (1).

7. A method for designing a fixture for improving high-frequency impedance of a differential mode filter inductor according to claim 6, characterized in that: The materials chosen for 3D printing technology are ABS, PLA or nylon.

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