A common mode inductor

Abstract

This application discloses a common-mode inductor, applicable to the field of electronic technology. The common-mode inductor includes M magnetic cores, 2N U-shaped coils, and a fixed base plate. M is a positive integer greater than or equal to 1, and N is a positive integer greater than or equal to 1. Each of the M magnetic cores is a hollow cylindrical structure with an axisymmetric cross-section. One end of each of the 2N U-shaped coils is inserted into the hollow portion of a magnetic core. The fixed base plate is used to fix the M magnetic cores and the 2N U-shaped coils. By using U-shaped coils to manufacture the common-mode inductor, the U-shaped coils can be directly wound onto the magnetic cores. This avoids uneven stress on the magnetic cores caused by manual winding, preventing core deformation and resulting in decreased electrical performance, thereby improving the inductance and performance of the common-mode inductor.

Description

[0001] This application is a divisional application. The original application has the application number 202110904544.0 and the original application date is August 6, 2021. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic technology, and more particularly to a common-mode inductor. Background Technology

[0003] A common-mode inductor, also called a common-mode choke, is used to filter common-mode electromagnetic interference signals. Essentially, a common-mode inductor is a bidirectional filter; it filters out common-mode electromagnetic interference on signal lines while simultaneously suppressing its own electromagnetic interference emissions, thus preventing interference with the normal operation of other electronic devices in the same electromagnetic environment.

[0004] A common-mode inductor consists of a magnetic core and windings wound around it, with the core needing to provide a closed magnetic circuit. The inductance of a common-mode inductor is related to the number of turns in both the core and the windings. The magnetic circuit provided by the core must be closed; any air gaps in the circuit will significantly reduce the inductance. The more turns the windings have on the core, the greater the inductance of the common-mode inductor. With increasing market demands and technological advancements, power supply currents are rising, and device integration is becoming increasingly sophisticated. Common-mode inductors are rapidly evolving towards smaller size, higher current capacity, higher saturation, higher density, higher thermal stability, higher frequency stability, higher anti-interference capabilities, and more automated manufacturing processes. Therefore, obtaining common-mode inductors with higher space utilization, higher integration, and higher power density has become a pressing issue. Summary of the Invention

[0005] This application provides a common-mode inductor that uses a U-shaped coil instead of a hand-wound coil. This reduces the stress on the magnetic core caused by hand-winding the coil and improves the stability of the common-mode inductor. Simultaneously, it enables automated processing of the entire manufacturing process, improving the manufacturing efficiency of the common-mode inductor.

[0006] The first aspect of this application provides a common-mode inductor, including: Common-mode inductors eliminate common-mode interference signals based on the principle of electromagnetic induction and consist of magnetic cores and coils. Specifically, a common-mode inductor includes M magnetic cores, 2N U-shaped coils, and a base plate for fixing the magnetic cores and U-shaped coils. M and N are both positive integers greater than or equal to 1. Each magnetic core is a closed cylindrical structure, such as a cylinder, cuboid, or cube, and this cylindrical structure is hollow. The cross-section of the magnetic core is axisymmetric, which facilitates the formation of two symmetrically distributed windings on the core to achieve common-mode interference signal elimination. Each U-shaped coil requires at least one end to be inserted into the hollow part of the cylindrical structure and wound around the magnetic core.

[0007] In the aforementioned common-mode inductor, inserting one end of the U-shaped coil into the hollow part of the magnetic core allows the coil to be wound around a closed magnetic core. This avoids the uneven stress on the magnetic core caused by manual winding, which can lead to core deformation and a decrease in inductance. This improves the inductance and electrical performance of the common-mode inductor. Furthermore, the U-shaped coil allows for automated production, improving coil consistency compared to manual winding, and simultaneously enhancing the electrical performance and production efficiency of the common-mode inductor.

[0008] In one optional embodiment, the common-mode inductor further includes an insulating isolation frame for isolating and securing the U-shaped coil. The insulating isolation frame is located in the hollow portion of the magnetic core, isolating one end of the U-shaped coil within the hollow portion and preventing contact between the end of the U-shaped coil inserted into the hollow portion and the coil itself. Using an insulating isolation frame to isolate the U-shaped coil eliminates the need for surface insulation treatment of the U-shaped coil, making the insulation method simpler and more efficient, and improving the production efficiency of the common-mode inductor.

[0009] In one alternative implementation, if the common-mode inductor has only one magnetic core, one end of the U-shaped coil needs to be inserted into the hollow portion of the magnetic core, while the other end protrudes from the outer surface of the core, allowing the U-shaped coil to wind around it. In this case, the common-mode inductor requires symmetrical windings. If the common-mode inductor comprises 2N U-shaped coils, N U-shaped coils need to be located on one side of the magnetic core to form one winding. The other N U-shaped coils need to be located on the other side of the magnetic core to form another winding, and the positions of the two windings need to be symmetrical about the axis of symmetry of the cross-section of the magnetic core.

[0010] The aforementioned common-mode inductor includes a closed magnetic core with two symmetrical windings distributed on it. Each winding includes the same number of U-shaped coils. Thus, the common-mode inductor can be manufactured simply by assembling the U-shaped coils, eliminating the need for manual winding and improving production efficiency.

[0011] In one optional implementation, the common-mode inductor may further include two magnetic cores to increase the inductance. When the common-mode inductor has two magnetic cores, one end of each U-shaped coil is inserted into the hollow portion of the first magnetic core, and the other end is inserted into the hollow portion of the second magnetic core. The 2N U-shaped coils also form two windings, with N U-shaped coils and the other N U-shaped coils symmetrically distributed, and the two windings are insulated from each other. In the above common-mode inductor, the increase in the number of magnetic cores can increase the inductance of the common-mode inductor to meet the needs of high-current, high-inductance scenarios.

[0012] In one alternative implementation, each winding of the common-mode inductor may include only one U-shaped coil, i.e., a single-turn coil. In this case, each U-shaped coil has an electrical connection wire at both ends, which is used to connect to an external circuit. This allows the common-mode inductor to be connected to an external circuit. When the current from the external circuit flows into the common-mode inductor through the electrical connection wire, the two windings undergo electromagnetic induction, forming a magnetic field with the same direction to impede the common-mode signal and achieve the filtering of common-mode interference signals.

[0013] In one alternative implementation, each winding in the common-mode inductor may further include multiple U-shaped coils, i.e., N U-shaped coils connected together to form a winding, thus forming two symmetrically distributed windings with 2N U-shaped coils. Specifically, the connection relationship between the N U-shaped coils is such that the first end of the i-th U-shaped coil is connected to the second end of the (i+1)-th U-shaped coil, i.e., the N U-shaped coils are connected in series to form a winding.

[0014] In one alternative implementation, when each winding in the common-mode inductor is formed by N U-shaped coils connected in series, the first end of the first U-shaped coil and the second end of the last U-shaped coil need to be connected to an electrical connection line so that the common-mode inductor can be connected to an external circuit. Common-mode interference signals from the external circuit can be passed into the common-mode inductor through the electrical connection line, so that the common-mode inductor can filter out common-mode interference signals.

[0015] In one alternative implementation, to further improve the inductance of the common-mode inductor, the magnetic core can be made of a nanocrystalline material with high permeability, which can improve the high-temperature saturation characteristics of the common-mode inductor and further improve the performance of the common-mode inductor.

[0016] In one optional implementation, when assembling a common-mode inductor, an insulating isolation frame can be placed first in the hollow portion of the magnetic core. Then, one end of each of 2N U-shaped coils is inserted into the hollow portion of the magnetic core. The insulating isolation frame serves to achieve insulation isolation between the 2N U-shaped coils and also to fix them in place. The mounting base plate for fixing the magnetic core and U-shaped coils includes copper wire insertion holes. After one end of each of the 2N U-shaped coils is inserted into the hollow portion of the magnetic core, the magnetic core is placed on the mounting base plate, and both ends of the U-shaped coils are inserted into the corresponding copper wire insertion holes on the mounting base plate, thus fixing the magnetic core and U-shaped coils.

[0017] In one alternative implementation, the cross-section of the magnetic core can be an axisymmetric figure of any shape, such as a square, rectangle, circle, ellipse, or racetrack.

[0018] In one alternative implementation, when each winding of the common-mode inductor includes multiple U-shaped coils, the multiple U-shaped coils need to be connected. Specifically, they can be connected by a printed circuit board, copper foil, or resistance soldering.

[0019] In one alternative implementation, the current flowing through the common-mode inductor can be a single-phase current, a two-phase current, or a three-phase current, without any specific limitation.

[0020] The aforementioned common-mode inductor comprises a closed magnetic core and a U-shaped coil. The closed magnetic core provides a closed magnetic circuit, reducing the core's magnetic reluctance and preventing inductance degradation. The U-shaped coil allows for automated production; simply inserting one end of the U-shaped coil into the hollow portion of the magnetic core winds the coil around the closed core, avoiding the uneven stress and deformation that can occur with manual winding, which leads to inductance degradation. This improves both the inductance and performance of the common-mode inductor. Furthermore, the automated production process of the U-shaped coil improves coil consistency compared to manual winding, enhancing both the electrical performance and production efficiency of the common-mode inductor. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a signal transmission circuit provided in an embodiment of this application; Figure 2 A physical structure diagram of a common-mode inductor provided in an embodiment of this application; Figure 3 A top view of a magnetic core provided for an embodiment of this application; Figure 4 A top view of a common-mode inductor provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of a U-shaped coil provided in an embodiment of this application; Figure 6 A physical structure diagram of another common-mode inductor provided in an embodiment of this application; Figure 7 A bottom view of another common-mode inductor provided in an embodiment of this application; Figure 8 A physical structure diagram of another common-mode inductor provided in an embodiment of this application; Figure 9 A top view of another common-mode inductor provided in an embodiment of this application; Figure 10 A top view of another common-mode inductor provided in an embodiment of this application. Detailed Implementation

[0022] This application provides a common-mode inductor that uses U-shaped copper wire instead of a hand-wound coil. This reduces the stress on the magnetic core during hand-winding and increases the inductance of the common-mode inductor. It also enables automated coil processing, improving the manufacturing efficiency of the common-mode inductor.

[0023] The technical terminology used in the embodiments of this invention is for illustrative purposes only and is not intended to limit the invention. In this document, the singular forms “a,” “the,” and “the” are used to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the use of “comprising” and / or “including” in the specification means the presence of the stated feature, integral, step, operation, element, and / or component, but does not preclude the presence or addition of one or more other features, integrals, steps, operations, elements, and / or components.

[0024] The equivalents (if any) of the corresponding structures, materials, actions, and all means or steps and functional elements in the appended claims are intended to include any structure, material, or action used in conjunction with other expressly claimed elements to perform the function. The description of the invention is given for the purposes of illustration and description, but is not intended to be exhaustive or to limit the invention to the forms disclosed.

[0025] Before introducing the common-mode inductor provided in the embodiments of this application, let's briefly introduce the concepts of common-mode signal and differential-mode signal. A common-mode signal refers to a signal with equal amplitude and the same phase. A differential-mode signal refers to a signal with equal amplitude and opposite phase. In a closed circuit, common-mode interference signals have equal amplitude and the same direction on two conductors; their essence is the interference caused by the voltage difference between the two traces and the ground wire in the closed loop.

[0026] Figure 1 This is a schematic diagram of a signal transmission circuit provided in an embodiment of this application. Figure 1 As shown, the signal transmission circuit includes wire 1 and wire 2. For wire 1, the signal transmission direction is from the first end to the second end. For wire 2, the signal transmission direction is from the second end to the first end. The normal signal amplitudes transmitted on wires 1 and 2 are equal, but their phases are opposite; that is, the normally transmitted signal is a differential-mode signal. However, common-mode interference exists in this signal transmission circuit. This common-mode interference is caused by the voltage difference between wires 1 and 2 and the ground wire. Half of this common-mode interference flows into wire 1, and half flows into wire 2. The common-mode interference on wires 1 and 2 has the same direction and equal amplitude.

[0027] Common-mode inductors are typically used to eliminate common-mode interference signals in signal transmission circuits. A common-mode inductor, also called a common-mode choke, is a common-mode interference suppression device with a ferrite core. It consists of two identical coils symmetrically wound on the same ferrite toroidal core, and includes four leads. For example... Figure 1 As shown, the two ends of the common-mode inductor are used to connect to wire 1, connecting one winding in series within wire 1. The other two ends are used to connect to wire 2, connecting the other winding in series within wire 2. The working principle of the common-mode inductor is described below: When the signal transmission circuit transmits a normal signal (differential mode signal), the currents in wire 1 and wire 2 are in opposite directions. According to the principle of electromagnetic induction, the magnetic fields generated by the two windings are in opposite directions. Thus, the magnetic fields generated by the coils cancel each other out, having no effect on the differential mode signal, allowing it to be transmitted normally. However, the common-mode interference signal present in the signal transmission circuit has equal amplitude and the same phase on wire 1 and wire 2. Therefore, the magnetic fields generated by the two windings due to the common-mode interference signal are in exactly the same direction. At this time, the magnetic fields superimpose, increasing the inductive reactance of the common-mode inductor, causing attenuation of the common-mode interference signal, thereby suppressing its transmission and achieving the purpose of filtering out common-mode interference signals.

[0028] As described above, common-mode inductors have the characteristics of not affecting the transmission of normal signals (differential-mode signals) and suppressing common-mode interference signals. Common-mode inductors require a closed magnetic circuit and symmetrically distributed coils to achieve filtering. In existing technologies, because the magnetic core is closed, windings are typically formed on the core by hand. This involves winding multiple strands of copper wire together to form symmetrical windings. This method cannot achieve automated production of common-mode inductors, resulting in low production efficiency. Furthermore, hand-wound windings have poor consistency, making it difficult to achieve uniformity and symmetry. Additionally, hand-winding subjectes the magnetic core to uneven stress, potentially leading to core deformation and a decrease in inductance. All of these factors severely affect the performance of the common-mode inductor.

[0029] To address the aforementioned issues, this application provides a novel common-mode inductor that utilizes a U-shaped coil to replace manually wound coils, enabling automated coil production. Furthermore, by simply inserting one end of the U-shaped coil into the center of the magnetic core, the coil can be wound onto the core without subjecting it to external stress, thus avoiding inductance reduction due to core cracking. This significantly improves the inductance and performance of the common-mode inductor.

[0030] The common-mode inductor provided in this application will be described in detail below with reference to the accompanying drawings.

[0031] (a) A common-mode inductor consists of a magnetic core: Figure 2 This is a physical structure diagram of a common-mode inductor provided for an embodiment of this application. For example... Figure 2 As shown, the common-mode inductor includes a magnetic core, two U-shaped coils, an insulating frame, and a fixed base plate.

[0032] The magnetic core is closed, forming a closed magnetic circuit. It is a hollow cylindrical structure with a cross-section that is axially symmetric. For example, the core could be a hollow cube, a hollow cuboid, or a hollow cylinder, etc., without specific limitations. The cross-section can be square (corresponding to a cube), rectangular (corresponding to a cuboid), or circular (corresponding to a cylinder), or it can be elliptical, isosceles triangle, or isosceles trapezoid, etc., as long as the cross-section is axially symmetric. This allows for diverse core shapes to adapt to specific spatial arrangement requirements.

[0033] Preferably, the cross-section of the magnetic core is racetrack-shaped, and the racetrack shape has a flat feature, which can improve the space utilization of the common mode inductor. Figure 3 This is a top view of a magnetic core provided as an embodiment of this application. Figure 3 As shown, the cross-section of the magnetic core is racetrack-shaped and has a ring-like structure. This is because the inside of the magnetic core is hollow, which facilitates the winding of the coil around the core. The racetrack shape can be seen as a combination of a rectangle with two short sides each connected to a semicircle. This shape has the highest space utilization and can effectively reduce the volume of the common-mode inductor.

[0034] Meanwhile, in order to increase the inductance of the common-mode inductor, the magnetic core can be made of nanocrystalline material with high permeability. This way, even if the number of coil turns is small, the inductance can be guaranteed, and the high-temperature saturation characteristics of the magnetic core can be improved, which greatly improves the performance of the common-mode inductor.

[0035] Two U-shaped coils are used to form two windings, meaning the common-mode inductor consists of two single-turn coils. The two U-shaped coils need to be wound symmetrically on the magnetic core. One end of each U-shaped coil is inserted into the hollow part of the magnetic core, while the other end protrudes from the outside of the core (on one side of the outer surface). Furthermore, the two U-shaped coils need to be positioned symmetrically about the axis of symmetry of the magnetic core's cross-section. For example... Figure 1 As shown, one U-shaped coil is located on the first side of the magnetic core, and the other U-shaped coil is located on the second side of the magnetic core. The first and second sides are symmetrical about the axis of symmetry of the cross-section of the magnetic core. To more intuitively illustrate the distribution of the two U-shaped coils, Figure 4 A top view of a common-mode inductor provided in an embodiment of this application, as shown below. Figure 4 As shown, the top view of the common-mode inductor is a racetrack-shaped, ring-like figure. The racetrack shape has an axis of symmetry L, and the two coils are symmetrically positioned about the axis of symmetry L. It can be understood that the cross-section of the common-mode inductor can include multiple axes of symmetry, and the U-shaped coils only need to be symmetrically distributed about any one of these axes; there is no specific limitation.

[0036] The following is an introduction to U-shaped coils. For example... Figure 5 As shown, the coil's shape resembles the letter "U," meaning it can consist of three parts: two parallel sides and an arc-shaped side. In a preferred embodiment, the arc-shaped side of the U-shaped coil can be replaced with a straight side, perpendicular to the two parallel sides, forming a "Π" shape. This further improves space utilization, allowing the coil to fit more closely to the magnetic core and further reducing the volume of the common-mode inductor. Understandably, the U-shaped coil described later can also be a "Π"-shaped coil, which will not be elaborated further.

[0037] The insulating frame is used to isolate and fix 2N U-shaped coils. When assembling a common-mode inductor, the frame can be placed in the hollow part of the magnetic core first, and then 2N U-shaped coils can be inserted into the remaining hollow part between the magnetic core and the frame to achieve insulation isolation between the 2N U-shaped coils, and at the same time, it can also fix the 2N U-shaped coils.

[0038] The mounting plate is used to fix the U-shaped coil and the magnetic core. The mounting plate has copper wire insertion holes. After passing through the magnetic core, the two ends of the U-shaped coil are inserted into the copper wire insertion holes to fix the common-mode inductor. In this embodiment, the mounting plate needs to have four copper wire insertion holes for inserting the two ends of two U-shaped coils, ultimately forming the four terminals of the common-mode inductor. Each end of each U-shaped coil is a terminal, from which an electrical connection wire can be led out. Through the electrical connection wire, the common-mode inductor can be connected to an external circuit. When common-mode interference signals are transmitted to the common-mode inductor, the common-mode inductor can suppress the common-mode interference signals, achieving a filtering effect.

[0039] The specifications of each component of a common-mode inductor are described below in conjunction with specific application scenarios: When common-mode inductors are used for output filtering in high-power rectifier modules, nanocrystalline materials with a frequency range of 50kHz to 100kHz and a permeability of 10,000 to 20,000 can be selected to form the magnetic core. Automated processing can be used to form a cylindrical, hollow, closed magnetic core, with the hollow portion reserved for the insertion of a U-shaped coil. For example, the core dimensions are between 18mm and 20mm in length, 14mm and 16mm in width, and 28mm and 30mm in height. The thickness of the core, i.e., the thickness of the annular cross-section, can be between 4mm and 5mm.

[0040] Meanwhile, flat copper wire with a cross-sectional length between 4mm and 5mm and a width between 1.5mm and 2mm can be selected to manufacture the U-shaped coil. The copper wire is bent through a mold, with the bending angle controlled between 80 degrees and 90 degrees, forming a U-shaped single-turn coil. Understandably, the U-shaped coil needs to pass through a magnetic core and also form terminals. Therefore, after bending the copper wire, the length of the U-shaped coil needs to be between 33mm and 35mm.

[0041] The base plate can be injection molded from commonly used materials. When assembling the common-mode inductor, the magnetic core can be placed on the base plate, and then copper wires can be inserted into the copper wire insertion holes on the base plate to ensure symmetrical distribution of the U-shaped coils. Finally, electrical connection wires are led out from both ends of the U-shaped coils.

[0042] The common-mode inductor described above can achieve an inductance of 110μH to 120μH at a frequency of 100kHz and a voltage of 1V, while the differential-mode inductance is only 0.5μH to 0.7μH. Furthermore, the common-mode inductor has a saturation voltage of 80A to 85A in differential mode, and its saturation characteristics also meet the requirements, significantly improving the performance of the common-mode inductor.

[0043] Understandably, the above description also applies to common-mode inductors that include multiple magnetic cores stacked sequentially. That is, regardless of the number of magnetic cores in a common-mode inductor, as long as the magnetic cores are stacked to form a "hole" for inserting a U-shaped coil, the situation is similar to the above description, and will not be repeated here. The embodiments of this application do not limit the number of magnetic cores.

[0044] Figure 6 A physical structural diagram of another common-mode inductor provided in an embodiment of this application. (See diagram below.) Figure 6 As shown, the common-mode inductor also includes a magnetic core, but it includes multiple U-shaped coils. According to the symmetry requirement of the common-mode inductor, the common-mode inductor includes 2N U-shaped coils. In this embodiment, N is a positive integer greater than 1.

[0045] Among them, magnetic core and Figure 2 The magnetic core in the illustrated embodiment is similar; please refer to the above for details, which will not be repeated here. To further improve the inductance of the common-mode inductor, the number of winding turns can be increased by increasing the number of U-shaped coils, thereby increasing the inductance of the common-mode inductor.

[0046] A common-mode inductor consists of 2N U-shaped coils, with N U-shaped coils forming the first winding and another N U-shaped coils forming the second winding. Similarly, the first and second windings must be symmetrically distributed. For example... Figure 6As shown, one end of the U-shaped coil is inserted into the hollow part of the magnetic core, while the other end remains on the outside (outer surface) of the core. The difference is that N U-shaped coils are distributed on the left side of the core, and another N U-shaped coils are distributed on the right side. The left and right sides are symmetrical about the axis of symmetry of the cross-section of the core. To more intuitively represent the distribution positions of the two sets of U-shaped coils, Figure 7 A bottom view of another common-mode inductor provided in an embodiment of this application, as shown below. Figure 7 As shown, the top view of a common-mode inductor can be racetrack-shaped, with an axis of symmetry L. If N equals 3, each of the two sets of U-shaped coils includes 3 U-shaped coils, whose distribution is symmetrical about the axis of symmetry L. It can be understood that a racetrack-shaped inductor can include multiple axes of symmetry, and the U-shaped coils only need to be symmetrically distributed about any one of these axes; the specific distribution is not limited.

[0047] The U-shaped coils in each group need to be connected together to form a winding. Taking a group of U-shaped coils as an example, each U-shaped coil in a group has two ends. The second end of the first U-shaped coil needs to be connected to the first end of the second U-shaped coil, and the second end of the second U-shaped coil needs to be connected to the first end of the third U-shaped coil. And so on, the second end of the (N-1)th U-shaped coil needs to be connected to the first end of the Nth U-shaped coil. That is, the U-shaped coils in each group need to be connected in series to form a winding, which is wound around the magnetic core. The first end of the first U-shaped coil and the second end of the Nth U-shaped coil are the two ends of this winding.

[0048] The first end of the first U-shaped coil and the second end of the Nth U-shaped coil can be led out as electrical connection wires for connecting to external circuits. Understandably, one set of U-shaped coils forms one winding, and two sets of U-shaped coils form two symmetrical windings. Similarly, this common-mode inductor includes four terminals.

[0049] The insulating frame is used to isolate and fix 2N U-shaped coils. When assembling a common-mode inductor, the frame can be placed in the hollow part of the magnetic core first, and then 2N U-shaped coils can be inserted into the remaining hollow part between the magnetic core and the frame to achieve insulation isolation between the 2N U-shaped coils, and at the same time, it can also fix the 2N U-shaped coils.

[0050] The mounting plate is used to fix the U-shaped coils and the magnetic core. The mounting plate has copper wire insertion holes. After passing through the magnetic core, the two ends of the U-shaped coils are inserted into the copper wire insertion holes to fix the common-mode inductor. In this embodiment, the mounting plate needs 4N copper wire insertion holes to insert the two ends of the two sets of U-shaped coils, ultimately forming the four terminals of the common-mode inductor. Specifically, the magnetic core can be placed on the mounting plate first, then 2N coils can be inserted into the hollow part of the magnetic core in sequence, then the two ends of the 2N coils can be inserted into the communication jacks, and finally, the coils of each set can be connected in series. This connection of the coils while they are fixed improves efficiency.

[0051] For example, when connecting U-shaped coils, the connection can be made by printed circuit board, copper foil or resistance soldering, and there is no specific limitation.

[0052] The specifications of each component of a common-mode inductor are described below in conjunction with specific application scenarios: When a common-mode inductor is used in a charging pile power module, a nanocrystalline material with a frequency of 100kHz to 120kHz and a permeability of 20,000 to 25,000 can be selected to form the magnetic core. Automated processing can be used to form a cylindrical, hollow, closed magnetic core, with the hollow portion reserved for the insertion of a U-shaped coil. For example, the core dimensions are between 36mm and 38mm in length, 20mm and 22mm in width, and 28mm and 30mm in height. The thickness of the core, i.e., the thickness of the annular cross-section, can be between 7mm and 8mm.

[0053] Simultaneously, flat copper wire with a cross-sectional length between 5mm and 6mm and a width between 1.5mm and 2mm can be selected to manufacture the U-shaped coil. The copper wire is bent through a mold, with the bending angle controlled between 80 and 90 degrees, forming a U-shaped single-turn coil. Understandably, the U-shaped coil needs to pass through a magnetic core and also form terminals. Therefore, after bending the copper wire, the length of one end of the U-shaped coil needs to be between 29mm and 31mm, while the other end needs to be connected to the next U-shaped coil, so the length of the other end of the U-shaped coil needs to be between 32mm and 34mm.

[0054] In the above description, the current flowing through the common-mode inductor can be a single-phase current or a three-phase current, without any specific limitation.

[0055] The aforementioned common-mode inductors all include a closed magnetic core and a U-shaped coil. The closed magnetic core provides a closed magnetic circuit, reducing the core's magnetic reluctance and preventing inductance degradation. The U-shaped coil allows for automated production; simply inserting one end of the coil into the hollow core and placing the other end outside the coil allows the coil to be wound around the closed core. This avoids the uneven stress on the core caused by manual winding, which can lead to core deformation and inductance degradation. This improves both the inductance and performance of the common-mode inductor. Furthermore, the automated production process of the U-shaped coil improves coil consistency compared to manual winding, enhancing both the electrical performance and production efficiency of the common-mode inductor.

[0056] (ii) A common-mode inductor consists of two magnetic cores: To further increase the inductance of a common-mode inductor, one can not only increase the number of turns in the coil, but also increase the number of magnetic cores to increase the magnetic flux. Figure 8 A physical structural diagram of another common-mode inductor provided in an embodiment of this application. (See diagram below.) Figure 8 As shown, the common-mode inductor includes two magnetic cores, two U-shaped coils, an insulating frame, and a fixed base plate.

[0057] Each of the two magnetic cores is closed, forming a closed magnetic circuit. Each core is a hollow cylindrical structure with an axially symmetric cross-section. The hollow portion serves as the insertion space for the U-shaped coil and the insulating frame. The core can be a hollow cube, hollow cuboid, or hollow cylinder, etc., with no specific limitation. The cross-section of the core can be square (corresponding to a cube), rectangular (corresponding to a cuboid), or circular (corresponding to a cylinder), or even elliptical or racetrack-shaped, but the cross-section must be axially symmetric. The two cores are in side contact, and the U-shaped coil needs to pass through both cores.

[0058] like Figure 8 As shown, the common-mode inductor includes two U-shaped coils, each inserted between two magnetic cores. Specifically, one end of each U-shaped coil is inserted into the hollow portion of the first magnetic core, and the other end is inserted into the hollow portion of the second magnetic core. The two U-shaped coils are insulated and fixed by a frame. To eliminate common-mode interference signals, the two coils must still be symmetrically distributed.

[0059] To more intuitively demonstrate the distribution of the two U-shaped coils, Figure 9 This is a top view of another common-mode inductor provided in an embodiment of this application. 901 is a top view of the first magnetic core, and 902 is a top view of the second magnetic core. Figure 9As can be seen, the two magnetic cores are in contact. The cross-sections of the two magnetic cores have an axis of symmetry M, which is perpendicular to the line S. The two U-shaped coils need to span the two magnetic cores, located between them. Furthermore, the positions of the two U-shaped coils need to be symmetrical about the axis of symmetry M; that is, the two U-shaped coils need to be symmetrically distributed on both sides of M.

[0060] The mounting plate is used to fix the U-shaped coil and the magnetic core. The mounting plate has copper wire insertion holes. After passing through the magnetic core, the two ends of the U-shaped coil are inserted into the copper wire insertion holes to fix the common-mode inductor. In this embodiment, the mounting plate needs to have four copper wire insertion holes for inserting the two ends of two U-shaped coils, ultimately forming the four terminals of the common-mode inductor. Each end of each U-shaped coil is a terminal, from which an electrical connection wire can be led out. Through the electrical connection wire, the common-mode inductor can be connected to an external circuit. When common-mode interference signals are transmitted to the common-mode inductor, the common-mode inductor can suppress the common-mode interference signals, achieving a filtering effect.

[0061] The specifications of each component of a common-mode inductor are described below in conjunction with specific application scenarios: When a common-mode inductor is used for input filtering in a high-power rectifier, a nanocrystalline material with a frequency between 100kHz and 150kHz and a permeability of 20,000 to 30,000 can be selected to form the magnetic core. Automated processing can be used to form a cylindrical, hollow, closed magnetic core, with the hollow portion reserved for the insertion of a U-shaped coil. For example, the core dimensions are between 14mm and 16mm in length, 9mm and 11mm in width, and 28mm and 30mm in height. The thickness of the core, i.e., the thickness of the annular cross-section, can be between 4mm and 5mm.

[0062] Meanwhile, flat copper wire with a cross-sectional length between 4mm and 5mm and a width between 1.5mm and 2mm can be selected to manufacture the U-shaped coil. The copper wire is bent through a mold, with the bending angle controlled between 80 degrees and 90 degrees, forming a U-shaped single-turn coil. Understandably, the U-shaped coil needs to pass through a magnetic core and also form terminals. Therefore, after bending the copper wire, the length of the U-shaped coil needs to be between 33mm and 35mm.

[0063] The base plate can be injection molded from commonly used materials. When assembling the common-mode inductor, the magnetic core can be placed on the base plate, and then copper wires can be inserted into the copper wire insertion holes on the base plate to ensure symmetrical distribution of the U-shaped coils. Finally, electrical connection wires are led out from both ends of the U-shaped coils.

[0064] Similarly, the above description also applies to common-mode inductors that include more magnetic cores, with multiple cores stacked sequentially. That is, regardless of the number of magnetic cores in a common-mode inductor, as long as the stacked cores form two "holes" for inserting U-shaped coils, the situation is similar to the above description, and will not be repeated here. The embodiments of this application do not limit the specific number of magnetic cores.

[0065] As described above, when a common-mode inductor includes two magnetic cores, its inductance can be further increased by increasing the number of U-shaped coils. Based on the symmetry requirement of the common-mode inductor, it comprises 2N U-shaped coils, where N is a positive integer greater than 1.

[0066] Among them, magnetic core and Figure 8 The magnetic core in the illustrated embodiment is similar; please refer to the above for details, which will not be repeated here. To further improve the inductance of the common-mode inductor, the number of winding turns can be increased by increasing the number of U-shaped coils, thereby increasing the inductance of the common-mode inductor.

[0067] A common-mode inductor consists of 2N U-shaped coils, with N U-shaped coils forming the first winding and another N U-shaped coils forming the second winding. Similarly, the first and second windings must be symmetrically distributed. For example... Figure 9 As shown, one end of each U-shaped coil is inserted into the hollow part of the first magnetic core, and the other end is inserted into the hollow part of the second magnetic core. The difference is that N C-shaped coils are distributed to the left of the axis of symmetry M, and the other N U-shaped coils are distributed to the right of the axis of symmetry M. To more intuitively represent the distribution positions of the two sets of U-shaped coils, Figure 10 A top view of another common-mode inductor provided in an embodiment of this application, as shown below. Figure 10 As shown, the top view of the common mode inductor can be two racetrack shapes with an axis of symmetry M. If N equals 3, each of the two sets of U-shaped coils includes 3 U-shaped coils, and their distribution positions are symmetrical about the axis of symmetry M.

[0068] The U-shaped coils in each group need to be connected together to form a winding. Taking a group of U-shaped coils as an example, each U-shaped coil in a group has two ends. The second end of the first U-shaped coil needs to be connected to the first end of the second U-shaped coil, and the second end of the second U-shaped coil needs to be connected to the first end of the third U-shaped coil. And so on, the second end of the (N-1)th U-shaped coil needs to be connected to the first end of the Nth U-shaped coil. That is, the U-shaped coils in each group need to be connected in series to form a winding, which is wound around the magnetic core. The first end of the first U-shaped coil and the second end of the Nth U-shaped coil are the two ends of this winding.

[0069] The first end of the first U-shaped coil and the second end of the Nth U-shaped coil can be led out as electrical connection wires for connecting to external circuits. Understandably, one set of U-shaped coils forms one winding, and two sets of U-shaped coils form two symmetrical windings. Similarly, this common-mode inductor includes four terminals.

[0070] The mounting plate is used to fix the U-shaped coil and the magnetic core. The mounting plate has copper wire insertion holes. After passing through the magnetic core, the two ends of the U-shaped coil are inserted into the copper wire insertion holes to fix the common-mode inductor. In this embodiment, the mounting plate needs 4N copper wire insertion holes to insert the two ends of two sets of Π-shaped coils, ultimately forming the four terminals of the common-mode inductor. Specifically, the magnetic core can be placed on the mounting plate first, then 2N coils can be inserted into the hollow part of the magnetic core in sequence, then the two ends of the 2N coils can be inserted into the communication jacks, and finally, the coils of each set can be connected in series. This connection of the coils while they are fixed improves efficiency.

[0071] For example, when connecting U-shaped coils, the connection can be made by printed circuit board, copper foil or resistance soldering, and there is no specific limitation.

[0072] The technical terminology used in the embodiments of this invention is for illustrative purposes only and is not intended to limit the invention. In this document, the singular forms “a,” “the,” and “the” are used to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the use of “comprising” and / or “including” in the specification means the presence of the stated feature, integral, step, operation, element, and / or component, but does not preclude the presence or addition of one or more other features, integrals, steps, operations, elements, and / or components.

[0073] The equivalents (if any) of the corresponding structures, materials, actions, and all means or steps and functional elements in the appended claims are intended to include any structure, material, or action used in conjunction with other expressly claimed elements to perform the function. The description of the invention is given for the purposes of illustration and description, but is not intended to be exhaustive or to limit the invention to the forms disclosed.

Claims

1. A common-mode inductor, characterized in that, The common-mode inductor includes: M magnetic cores, 2N U-shaped coils, an insulating frame, and a fixed base plate; where M is a positive integer greater than or equal to 1, and N is a positive integer greater than or equal to 1. The magnetic core is disposed on the fixed base plate, and each of the M magnetic cores is a hollow cylindrical structure; and the cross-section of the cylindrical structure is an axisymmetric figure. The insulating isolation frame is disposed in the hollow part of the magnetic core and is used to isolate and fix the 2N U-shaped coils; One end of each of the 2N U-shaped coils is used to insert into the hollow portion between the magnetic core and the insulating frame; The base plate includes insertion holes for fixing the 2N U-shaped coils.

2. The common-mode inductor according to claim 1, characterized in that, The M is equal to 1; The other end of each U-shaped coil is located on the outside of the magnetic core; Of the 2N U-shaped coils, N U-shaped coils are located on the first side of the magnetic core, and the other N U-shaped coils are located on the second side of the magnetic core. The first side and the second side are symmetrical about the axis of symmetry of the annular pattern.

3. The common-mode inductor according to claim 1, characterized in that, The value of M is 2; Each U-shaped coil includes a first end and a second end, the first end being used to insert into the hollow portion of a first magnetic core, and the second end being used to insert into the hollow portion of a second magnetic core.

4. The common-mode inductor according to any one of claims 1 to 3, characterized in that, The N is equal to 1; Each U-shaped coil has an electrical connection wire at both ends, which is used to connect to an external circuit to energize the common-mode inductor.

5. The common-mode inductor according to any one of claims 1 to 3, characterized in that, The N is greater than 1; In the N U-shaped coils, the second end of the i-th U-shaped coil is connected to the first end of the (i+1)-th U-shaped coil; where i is a positive integer greater than or equal to 1 and less than N.

6. The common-mode inductor according to claim 5, characterized in that, Among the N U-shaped coils, the first end of the first U-shaped coil and the second end of the Nth U-shaped coil have an electrical connection line, which is used to connect to an external circuit to energize the common-mode inductor.

7. The common-mode inductor according to any one of claims 1 to 6, characterized in that, The magnetic core is made of nanocrystals or magnetic materials with high permeability.

8. The common-mode inductor according to any one of claims 1 to 7, characterized in that, The fixed base plate includes 4N copper wire insertion holes, and the 2N U-shaped coils correspond to the 4N copper wire insertion holes. The 4N copper wire insertion holes are used to insert the two ends of the 2N U-shaped coils.

9. The common-mode inductor according to any one of claims 1 to 8, characterized in that, The cross-section of the column structure is racetrack-shaped, square, rectangular, circular, or elliptical.

10. The common-mode inductor according to any one of claims 6 to 9, characterized in that, In the N coils, every two coils are connected by a printed circuit board, copper foil, or resistance soldering.

11. The common-mode inductor according to any one of claims 1 to 9, characterized in that, The current flowing through the common-mode inductor includes single-phase current or three-phase current.

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