Integrated common-mode inductoe and switching power converter having the same

Abstract

An integrated common-mode inductor includes an iron core, a first winding, a second winding, and a third winding. The iron core includes a center magnetic part, a first side magnetic part, and a second side magnetic part. The first winding is wound around the second side magnetic part, and wound around the first side magnetic part. The second winding is wound around the second side magnetic part. The third winding is wound around the second side magnetic part. The first winding wound around the first side magnetic part provides a differential-mode magnetic flux. The first winding, the second winding, and the third winding wound around the second side magnetic part provide a common-mode magnetic flux.

Description

Technical Field

[0001] This invention relates to an integrated common-mode inductor, and more particularly to an integrated common-mode inductor with common-mode noise and differential-mode noise cancellation. Prior Technology

[0002] In conventional switched-mode power converters, a common-mode noise filter (including capacitors C1 and C2) is typically located at the input. This filter usually consists of one to three sets of common-mode noise filters. Multiple filters are necessary because conducted electromagnetic interference has a bandwidth ranging from 150kHz to 30MHz, while filters typically have a limited response bandwidth.

[0003] The performance of a filter is directly related to its attenuation performance within the bandwidth. To achieve better noise attenuation, traditional common-mode inductors have two windings, N1 and N2, and require a higher inductance value, resulting in higher size and cost. Furthermore, high-inductance inductors typically require more windings, leading to greater efficiency loss and heat generation. Figure 1 shows a circuit diagram of a first embodiment of a conventional switching power converter. As can be clearly seen from Figure 1, the common-mode current (icm) is typically transmitted to ground (FG) via the secondary side, then returns to ground (FG) through ground, and is finally detected by the EMI receiver.

[0004] Furthermore, as shown in Figures 2 and 3, these are circuit diagrams of the second and third embodiments of existing switching power converters, respectively. Compared to Figure 1, although inductors with three coupled windings (N1, N2, N3) are used as common-mode noise cancellation filters 93A and 93B, which have excellent effects on eliminating common-mode noise, they have no effect on differential-mode noise. Therefore, in the circuits of Figures 2 and 3, it is still necessary to use a physical independent differential-mode filter inductor 92, which will hinder the miniaturization of electronic products.

[0005] Specifically, please refer to Figure 4, which shows the inductor structure of the differential-mode filter inductor 92 in Figures 2 and 3. In this structure, the inductor core of the differential-mode filter inductor 92 is separate from the inductor cores of the common-mode noise cancellation filters 93A and 93B, and each has an independent winding wound around it. The winding wound around the inductor core of the differential-mode filter inductor 92 is winding NX, while the windings around the inductor cores of the common-mode noise cancellation filters 93A and 93B are windings N1, N2, and N3. Therefore, as mentioned earlier, this separate inductor core architecture makes it difficult to reduce the inductor size, thus hindering the miniaturization of electronic products.

[0006] Therefore, how to design an integrated common-mode inductor to solve the problems and technical bottlenecks of existing technologies is an important research topic for the inventors of this case. Summary of the Invention

[0007] One objective of this invention is to provide an integrated common-mode inductor. This integrated common-mode inductor includes a core, a first winding, a second winding, and a third winding. The core includes a central magnetic conductor, a first side magnetic conductor, and a second side magnetic conductor. The first winding has a first end and a second end, wherein the first winding is wound on the second side magnetic conductor, forming a structure where the first end and the second end respectively exit from the first side magnetic conductor and the second side magnetic conductor. The second winding has a first end and a second end, wherein the second winding is wound on the second side magnetic conductor, forming a structure where the first end and the second end respectively exit from both sides of the second side magnetic conductor. The third winding has a first end and a second end, wherein the third winding is wound on the second side magnetic conductor, forming a structure where the first end and the second end respectively exit from both sides of the second side magnetic conductor. The first winding wound on the first side magnetic conductor provides differential-mode magnetic flux. The first, second, and third windings wound on the second side column magnetic conductor provide common-mode magnetic flux.

[0008] In one embodiment, the first winding is wound on the second side post magnetic conductor and extends directly onto the first side post magnetic conductor.

[0009] In one embodiment, the first winding is wound on the second side post magnetic conductor and is wound on the first side post magnetic conductor through a circuit board.

[0010] In one embodiment, the first side-pillar magnetic conductor and the central magnetic conductor provide a differential-mode closed magnetic path for the differential-mode flux. The second side-pillar magnetic conductor and the central magnetic conductor provide a common-mode closed magnetic path for the common-mode flux.

[0011] In one embodiment, the direction of the differential mode closed magnetic circuit in the central magnetic conductor is the same as the direction of the common mode closed magnetic circuit in the central magnetic conductor.

[0012] In one embodiment, at a time-varying instant, the first side column magnetic conductor and the central magnetic conductor form a clockwise differential mode closed magnetic circuit; the second side column magnetic conductor and the central magnetic conductor form a counterclockwise common mode closed magnetic circuit.

[0013] In one embodiment, at a time-varying instant, the first side column magnetic conductor and the central magnetic conductor form a counterclockwise differential mode closed magnetic circuit; the second side column magnetic conductor and the central magnetic conductor form a clockwise common mode closed magnetic circuit.

[0014] In one embodiment, the polarity of the first winding, which exits from the same side of the second column magnetic conductor, is the same as the polarity of the second winding and the third winding.

[0015] Another object of the present invention is to provide a switching power converter. The switching power converter includes a transformer, a primary-side circuit, and a voltage conversion circuit. The transformer has a primary side and a secondary side. The primary-side circuit is coupled to the primary side. The primary-side circuit includes a power impedance stabilization network and a noise cancellation circuit. The power impedance stabilization network receives input power. The noise cancellation circuit includes a first capacitor, an integrated common-mode inductor, and a second capacitor. The integrated common-mode inductor is coupled to the first capacitor. The second capacitor is coupled to the integrated common-mode inductor. The voltage conversion circuit is coupled between the integrated common-mode inductor and the primary side.

[0016] In one embodiment, the first capacitor is coupled between the output side of the power supply impedance stabilization network and the input side of the common-mode inductor.

[0017] In one embodiment, the first capacitor is coupled between the second end of the first winding and the second end of the second winding and the second end of the third winding.

[0018] In one embodiment, a first capacitor is coupled between an extension of a first winding and a second end of a second winding and a second end of a third winding. The second end of the second winding is coupled to the second end of the third winding, and the first end of the second capacitor is coupled to the first end of the third winding. The second end of the second capacitor is also coupled to ground.

[0019] In one embodiment, the first end of the second winding is coupled to the first end of the third winding, and the first end of the second capacitor is coupled to the second end of the third winding, and the second end of the second capacitor is coupled to ground.

[0020] In one embodiment, the third winding generates a reverse current equivalent to the common-mode noise current.

[0021] In one embodiment, the noise cancellation circuit functions as a current converter.

[0022] In one embodiment, the noise cancellation circuit further functions as a signal amplifier and / or signal converter.

[0023] In one embodiment, the primary-side circuit further includes a protection circuit. The protection circuit is coupled to the primary side of the transformer.

[0024] Therefore, the integrated common-mode inductor proposed in this invention has the following features and advantages: 1. Without adding independent magnetic components, a shared iron core magnetic circuit can be used as an integrated inductor, which helps in the miniaturization of components. 2. Reduces the EMI interference emission intensity of common-mode and differential-mode noise currents. 3. The common-mode noise cancellation circuit structure composed entirely of passive components clearly shows through experimental results that the same components can achieve better common-mode noise cancellation performance after adopting common-mode noise cancellation methods. 4. Compared with traditional passive LC filters, with the same number of components, this invention only requires the addition of a third winding. However, since the third winding only carries a small current, it only needs to use a thinner enameled wire diameter, without significantly increasing the size and cost of the coupled inductor. 5. Achieves higher filtering performance with a small common-mode inductor (CM choke), and the small CM choke has fewer windings and a smaller size, which helps in high-efficiency / miniaturized design. 6. The newly added third winding is wound in parallel with the original winding, and the thin wire diameter of the third winding (low current) does not significantly increase the cost. 7. The all-passive component design has high reliability.

[0025] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the scope of this invention. Simple Explanation of the Diagram

[0026] Figure 1: A circuit diagram of a first embodiment of a conventional switching power converter.

[0027] Figure 2: This is a circuit diagram of a second embodiment of an existing switching power converter.

[0028] Figure 3: A circuit diagram of a third embodiment of an existing switching power converter.

[0029] Figure 4: A schematic diagram of the inductor core structure in the form of the separate forms shown in Figures 2 and 3.

[0030] Figure 5A: is a schematic diagram of the first embodiment of the integrated common-mode inductor of the present invention.

[0031] Figure 5B is a schematic diagram of the second embodiment of the integrated common-mode inductor of the present invention.

[0032] Figure 6A: is a circuit diagram of the first embodiment of the switching power converter of the present invention using an integrated common-mode inductor.

[0033] Figure 6B: is a circuit diagram of a second embodiment of the switching power converter of the present invention using an integrated common-mode inductor.

[0034] Figure 7A: is a circuit diagram of the third embodiment of the switching power converter of the present invention using an integrated common-mode inductor.

[0035] Figure 7B: is a circuit diagram of the fourth embodiment of the switching power converter of the present invention using an integrated common-mode inductor. Implementation

[0036] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings.

[0037] The following describes the implementation of this invention through specific embodiments. Those skilled in the art can easily understand the other advantages and effects of this invention from the content disclosed in this specification. This invention can also be implemented or applied through other different specific examples, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of this invention.

[0038] It should be noted that the structures, proportions, sizes, numbers of components, etc. shown in the drawings attached to this specification are only used to配合 the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to限定 the implementation conditions of this creation. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that this creation can produce and the purposes that can be achieved, should fall within the scope that can be covered by the technical content disclosed in this creation.

[0039] Please refer to FIG. 5A, which is a schematic diagram of the first embodiment of the integrated common-mode inductor of the present invention. The integrated common-mode inductor 100 includes a magnetic core 10, a first winding N1, a second winding N2, and a third winding N3. The magnetic core 10 includes a central magnetic conductor 11, a first side-column magnetic conductor 21, and a second side-column magnetic conductor 22. Incidentally, the central magnetic conductor 11 can also be called the middle column, and the first side-column magnetic conductor 21 and the second side-column magnetic conductor 22 can also be called the first side column and the second side column. The material of the magnetic core 10 can be a ceramic magnetic material or a metal soft magnetic material. For ceramic magnetic materials, they are mainly materials such as nickel-zinc ferrite, manganese-zinc ferrite, magnesium-copper-zinc ferrite, etc.; for metal soft magnetic materials, they are mainly ferroalloy magnetic powders such as carbon-based iron powder, iron-nickel, iron-silicon, iron-silicon-aluminum, iron-silicon-chromium, amorphous alloy, etc.

[0040] Furthermore, the magnetic core 10 of the present invention can be a "day" - shaped structure to provide the central magnetic conductor 11, the first side-column magnetic conductor 21, and the second side-column magnetic conductor 22. Specifically, the "day" - shaped magnetic core 10 can be an integrally formed structure, or a two-piece structure, such as composed of an E-shaped magnetic core and an I-shaped magnetic core, or composed of a C-shaped magnetic core and a T-shaped magnetic core, or composed of two E-shaped magnetic cores, but this does not limit the present invention.

[0041] The first winding N1 has a first end and a second end. The first winding N1 is wound around the second side-column magnetic conductor 22 and directly extends and winds around the first side-column magnetic conductor 21, forming a structure where the first end and the second end lead out from the first side-column magnetic conductor 21 and the second side-column magnetic conductor 22 respectively. As shown in FIG. 5A, for example, the first end of the first winding N1 is the lead-out end at the upper right of the front view of FIG. 5A, and the second end of the first winding N1 is the lead-out end at the upper left of the front view of FIG. 5A. Or, the first end of the first winding N1 is the lead-out end at the upper left of the front view of FIG. 5A, and the second end of the first winding N1 is the lead-out end at the upper right of the front view of FIG. 5A.

[0042] The second winding N2 has a first end and a second end, wherein the second winding N2 is wound on the second side post magnetic conductor 22, forming a structure in which the first end and the second end respectively exit from both sides of the second side post magnetic conductor 22. As shown in Figure 5A, for example, the first end of the second winding N2 is the exit end in the upper right of the front view 5A, and the second end of the second winding N2 is the exit end in the lower right of the front view 5A. Alternatively, the first end of the second winding N2 is the exit end in the lower right of the front view 5A, and the second end of the second winding N2 is the exit end in the upper right of the front view 5A.

[0043] The third winding N3 has a first end and a second end, wherein the third winding N3 is wound on the second side post magnetic conductor 22, forming a structure in which the first end and the second end respectively exit from both sides of the second side post magnetic conductor 22. As shown in Figure 5A, for example, the first end of the third winding N3 is the exit end in the upper right of the front view 5A, and the second end of the third winding N3 is the exit end in the lower right of the front view 5A. Alternatively, the first end of the third winding N3 is the exit end in the lower right of the front view 5A, and the second end of the third winding N3 is the exit end in the upper right of the front view 5A.

[0044] The first winding N1, wound on the first side post magnetic conductor 21, provides differential mode magnetic flux ΦDM. The first winding N1, the second winding N2, and the third winding N3, wound on the second side post magnetic conductor 22, provide common mode magnetic flux ΦCM.

[0045] Specifically, the first side-pillar magnetic conductor 21 and the central magnetic conductor 11 provide the differential-mode closed magnetic circuit through which the differential-mode flux ΦDM passes. As shown in Figure 5A, at an instant of alternating time-varying AC, the differential-mode flux ΦDM forms a clockwise differential-mode closed magnetic circuit through the first side-pillar magnetic conductor 21 and the central magnetic conductor 11. The second side-pillar magnetic conductor 22 and the central magnetic conductor 11 provide the common-mode closed magnetic circuit through which the common-mode flux ΦCM passes. As shown in Figure 5A, at an instant of alternating time-varying AC, the common-mode flux ΦCM forms a counterclockwise common-mode closed magnetic circuit through the second side-pillar magnetic conductor 22 and the central magnetic conductor 11. Therefore, the direction of the differential-mode closed magnetic circuit in the central magnetic conductor 11 is the same as the direction of the common-mode closed magnetic circuit in the central magnetic conductor 11. For example, the direction of the differential-mode closed magnetic circuit in the central magnetic conductor 11 is downward from the perspective of the front view 5A, and the direction of the common-mode closed magnetic circuit in the central magnetic conductor 11 is downward from the perspective of the front view 5A. Therefore, the direction of the differential-mode closed magnetic circuit in the central magnetic conductor 11 is the same as the direction of the common-mode closed magnetic circuit in the central magnetic conductor 11.

[0046] However, this does not limit the invention. That is, at another instant of alternating time-varying flux, the differential-mode flux ΦDM forms a counter-clockwise closed differential-mode magnetic circuit with the first side-pillar magnetic conductor 21 and the central magnetic conductor 11. The common-mode flux ΦCM forms a clockwise closed common-mode magnetic circuit with the second side-pillar magnetic conductor 22 and the central magnetic conductor 11. Therefore, the direction of the differential-mode closed magnetic circuit in the central magnetic conductor 11 is the same as the direction of the common-mode closed magnetic circuit in the central magnetic conductor 11; that is, the directions of both the differential-mode and common-mode closed magnetic circuits in the central magnetic conductor 11 are upwards from the viewing angle of the front view 5A.

[0047] Therefore, by extending the first winding N1 from one side post (e.g., the second side post magnetic conductor 22) of the iron core 10 to the other side post (e.g., the first side post magnetic conductor 21) of the iron core 10, a differential mode closed magnetic circuit with a differential mode flux ΦDM is further realized in addition to the existing common mode closed magnetic circuit with common mode flux ΦCM. Thus, as can be seen from Figure 5A, without adding independent magnetic components, the shared iron core magnetic circuit can be used as an integrated inductor, which helps to miniaturize the component.

[0048] Please refer to Figure 5B, which is a schematic diagram of the second embodiment of the integrated common-mode inductor of the present invention. Compared with the first embodiment shown in Figure 5A, the first winding N1 is wound on the second side-pillar magnetic conductor 22 and is wound on the first side-pillar magnetic conductor 21 through the circuit board 200. In other words, the first winding N1 wound on the second side-pillar magnetic conductor 22 does not extend directly to the first side-pillar magnetic conductor 21 as shown in Figure 5A, but indirectly through the circuit board 200, and utilizes the electrical connection on the circuit board 200 to allow the first winding N1 wound on the second side-pillar magnetic conductor 22 to be wound on the first side-pillar magnetic conductor 21 through the circuit board 200. In this way, the technical features and effects of Figure 5A can also be achieved. Incidentally, although Figures 5A and 5B disclose the means of winding the first winding N1 on the second side-pillar magnetic conductor 22 and the first side-pillar magnetic conductor 21, this is not intended to limit the present invention. Any method that enables the first winding N1 to be wound around the second side post magnetic conductor 22 and the first side post magnetic conductor 21 should be included in the scope of this invention.

[0049] Please refer to Figure 6A, which is a circuit diagram of a first embodiment of the switching power converter using an integrated common-mode inductor according to the present invention. As shown in the figure, the switching power converter includes a transformer 96, a primary-side circuit, and a secondary-side circuit. The transformer 96 has a primary side and a secondary side. The primary-side circuit is coupled to the primary side, and the secondary-side circuit is coupled to the secondary side.

[0050] The primary-side circuit includes a power impedance stabilization network 91, a first capacitor CX1, an integrated common-mode inductor 100, a second capacitor Cm, a bridge rectifier 94, and a voltage conversion circuit 95. Furthermore, the primary-side circuit may also include a protection circuit 97. It is worth noting that the bridge rectifier 94 is used to convert AC power to DC power; therefore, when the input power is AC, a bridge rectifier 94 is required, and conversely, when the input power is DC, the bridge rectifier 94 can be omitted. The first capacitor CX1, the integrated common-mode inductor 100, and the second capacitor Cm constitute a noise cancellation circuit.

[0051] The following explanation uses AC power Vac as the input power source, but this is not intended to limit the invention; that is, the input power source can also be DC power. The line impedance stabilization network (LISN) 11 receives the AC power Vac. It is worth noting that all electronic devices must pass EMI conducted testing before they can be sold. In conducted testing, noise from the telecommunication port can interfere with call quality and network transmission rates. Therefore, most telecommunications equipment, in addition to testing the conducted power supply, also requires ISN testing for interference at the telecommunication port. LISN and ISN are used in this testing; the power supply side is usually called LISN testing, and the output port test is called ISN testing. LISN is used in EMI conducted testing to isolate the power grid from the device under test and couple the interference signal from the device under test to the EMC analyzer.

[0052] In the embodiment of FIG6A, the first capacitor CX1 is disposed between the output side of the power supply impedance stabilization network 91 and the input side of the integrated common mode inductor 100. Specifically, the first capacitor CX1 is disposed between the second end of the first winding N1 and the second end of the second winding N2 and the second end of the third winding N3.

[0053] The integrated common-mode inductor 100 series is a three-coupling winding inductor, meaning the inductor has three coupled windings: a first winding N1, a second winding N2, and a third winding N3. The designations N1, N2, and N3 also represent the turns ratio of the three windings, i.e., the turns ratio of the first winding N1, the second winding N2, and the third winding N3 is N1:N2:N3. Referring to Figure 5A, the second end of the first winding N1, which exits from the first side post magnetic conductor 21, is connected to the power supply impedance stabilization network 91, and the second ends of the second winding N2 and the third winding N3, which exit from the second side post magnetic conductor 22, are also connected to the power supply impedance stabilization network 91. Furthermore, the first end of the first winding N1, which is connected to the second side column magnetic conductor 22, is connected to the bridge rectifier 94, and the first end of the second winding N2 and the first end of the third winding N3, which are connected to the second side column magnetic conductor 22, are connected to the bridge rectifier 94.

[0054] In this embodiment, the second end (i.e., the input end) of the third winding N3 is coupled to the second end (i.e., the input end) of the second winding N2, and the first end (i.e., the output end) of the third winding N3 is coupled to the second capacitor Cm. Specifically, the output end of the third winding N3 is coupled to the first end of the second capacitor Cm, and the second end of the second capacitor Cm is coupled to ground.

[0055] Furthermore, in this embodiment, the polarity of the first winding N1, which has a wire exiting from the same side of the second side column magnetic conductor 22, is the same as the polarity of the second winding N2 and the third winding N3. That is, the polarity of the first end of the first winding N1 is the same as the polarity of the first end of the second winding N2 and the first end of the third winding N3.

[0056] The two input terminals of the bridge rectifier 94 are respectively coupled to the output terminals of the first winding N1 and the second winding N2. In this embodiment, the bridge rectifier 94 can be an active bridge rectifier (composed of active switching bridge arms) or a passive bridge rectifier (composed of diode switching bridge arms).

[0057] The voltage conversion circuit 95 is coupled between the bridge rectifier 94 and the primary side of the transformer 96. In this embodiment, the voltage conversion circuit 95 can be a boost circuit, a bulk circuit, or a buck-boost circuit. As mentioned above, if the bridge rectifier 94 is not required, the voltage conversion circuit 95 is coupled between the output terminal of the first winding N1, the output terminal of the second winding N2, and the primary side.

[0058] Protection circuit 97 is coupled to the primary side of transformer 96. In this embodiment, protection circuit 97 may be a clamping circuit, such as an RCD clamping circuit; or a snubber circuit, such as an RCD snubber circuit. However, the protection circuit 97 of the present invention is not limited to the above embodiment; any circuit that can be used to protect the primary side of transformer 96 can be used as the protection circuit 97 of this invention. The secondary side circuit includes an output rectifier 98 coupled to the load.

[0059] Therefore, the present invention is characterized by the use of a three-coupling winding inductor with three windings, N1, N2, and N3, from which the reverse common-mode noise current icm can be provided by the third winding N3. The current path of this newly added reverse common-mode noise current icm can replace the sum of the currents (icm / 2 + icm / 2) of the first winding N1 and the second winding N2. Since the current path of the newly added reverse common-mode noise current icm in the third winding N3 is shorter and has lower impedance, while the ground FG path of the power supply impedance stabilization network (LISN) 91 is longer and has higher impedance, the reverse common-mode noise current icm no longer passes through the power supply impedance stabilization network (LISN) 91. In other words, the power supply impedance stabilization network (LISN) 91 will not detect the current noise of the reverse common-mode noise current icm.

[0060] Please refer to Figure 6B, which is a circuit diagram of a second embodiment of the switching power converter using an integrated common-mode inductor according to the present invention. Compared with the first embodiment shown in Figure 6A, the first capacitor CX1 shown in Figure 6B is disposed between the extension of the first winding N1 (i.e., the winding segment extending from the second side column magnetic conductor 22 to the first side column magnetic conductor 21) and the second end of the second winding N2 and the second end of the third winding N3. The remaining identical contents are described in the corresponding description in Figure 6A, and will not be repeated here.

[0061] Please refer to Figure 7A, which is a circuit diagram of the third embodiment of the switching power converter using an integrated common-mode inductor according to the present invention. Compared with the first embodiment shown in Figure 6A, the connection method of the second capacitor Cm shown in Figure 7A is different from that of the first embodiment shown in Figure 6A. Specifically, the first end (i.e., the input end) of the third winding N3 is coupled to the first end (i.e., the output end) of the second winding N2, and the second end (i.e., the output end) of the third winding N3 is coupled to the second capacitor Cm. Specifically, the output end of the third winding N3 is coupled to the first end of the second capacitor Cm, and the second end of the second capacitor Cm is coupled to ground. For the rest of the same content, please refer to the corresponding description in Figure 7A, which will not be repeated here.

[0062] Please refer to Figure 7B, which is a circuit diagram of the fourth embodiment of the switching power converter using an integrated common-mode inductor according to the present invention. Compared with the third embodiment shown in Figure 7A, the first capacitor CX1 shown in Figure 7B is disposed between the extension of the first winding N1 (i.e., the winding segment extending from the second side column magnetic conductor 22 to the first side column magnetic conductor 21) and the second end of the second winding N2 and the second end of the third winding N3. The rest are the same as those in Figure 7A, and will not be repeated here.

[0063] In summary, the present invention has the following features and advantages:

[0064] 1. Without adding new independent magnetic components, a shared iron core magnetic circuit can be used as an integrated inductor, which helps to miniaturize the component.

[0065] 2. Reduce the EMI interference emission intensity of common-mode and differential-mode noise currents.

[0066] 3. The common-mode noise cancellation circuit structure composed entirely of passive components clearly shows from experimental results that the same components can achieve better common-mode noise cancellation performance after adopting common-mode noise cancellation methods.

[0067] 4. Compared to traditional passive LC filters, with the same number of components, this invention only requires the addition of a third winding. However, since the third winding only carries a small current, it only needs to use fine enameled wire without significantly increasing the size and cost of the coupling inductor.

[0068] 5. Higher filtering performance can be achieved by using small common mode inductors (CM chokes), and small CM chokes have fewer windings and smaller size, which helps in high-efficiency / miniaturized designs.

[0069] 6. The newly added third winding is wound in parallel with the original winding, and the wire diameter of the third winding is small (low current), so the increase in cost is not significant.

[0070] 7. The reliability of the all-passive component design is relatively high.

[0071] The above description is merely a detailed explanation and illustration of preferred embodiments of the present invention. However, the features of the present invention are not limited thereto and are not intended to limit the present invention. The scope of the present invention should be determined by the following claims. All embodiments that conform to the spirit of the claims and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the following claims.

[0072] 100: Integrated common mode inductor 10: Iron core 11: Central magnetic conductor 21: First side column magnetic conductor 22: Second side column magnetic conductor N1: First winding N2: Second winding N3: Third winding ΦDM: Differential mode flux ΦCM: Common mode flux 91: Power Impedance Stabilization Network 94: Bridge rectifier 95: Voltage conversion circuit 96: Transformer 97: Protection Circuit 98: Output rectifier CX1: First capacitor Cm: Second capacitor ICM: Reverse common-mode noise current FG: Earth 200: Circuit board

Claims

1. An integrated common-mode inductor, comprising: A core includes a central magnetic conductor, a first side magnetic conductor, and a second side magnetic conductor; a first winding having a first end and a second end, wherein the first winding is wound on the second side magnetic conductor and formed a structure in which the first end and the second end respectively exit the first side magnetic conductor and the second side magnetic conductor; a second winding having a first end and a second end, wherein the second winding is wound on the second side magnetic conductor and formed a structure in which the first end and the second end respectively exit the sides of the second side magnetic conductor; and a third winding having a first end and a second end, wherein the third winding is wound on the second side magnetic conductor and formed a structure in which the first end and the second end respectively exit the sides of the second side magnetic conductor. The first winding wound on the first side column magnetic conductor provides a differential mode magnetic flux; the first winding, the second winding, and the third winding wound on the second side column magnetic conductor provide a common mode magnetic flux.

2. The integrated common-mode inductor as described in claim 1, wherein the first winding is wound on the second side post magnetic conductor and extends directly on the first side post magnetic conductor.

3. The integrated common-mode inductor as described in claim 1, wherein the first winding is wound on the second side post magnetic conductor and is wound on the first side post magnetic conductor through a circuit board.

4. The integrated common-mode inductor as described in claim 1, wherein the first side column magnetic conductor and the center magnetic conductor provide a differential-mode closed magnetic path through which the differential-mode flux passes; wherein the second side column magnetic conductor and the center magnetic conductor provide a common-mode closed magnetic path through which the common-mode flux passes.

5. The integrated common-mode inductor as described in claim 4, wherein the differential-mode closed magnetic circuit is oriented in the same direction as the common-mode closed magnetic circuit in the same direction as the central magnetic conductor.

6. The integrated common-mode inductor as described in claim 5, wherein at a time-varying instant, the first side column magnetic conductor and the center magnetic conductor form a clockwise differential-mode closed magnetic circuit; and the second side column magnetic conductor and the center magnetic conductor form a counterclockwise common-mode closed magnetic circuit.

7. The integrated common-mode inductor as described in claim 5, wherein at a time-varying instant, the first side column magnetic conductor and the center magnetic conductor form a counterclockwise closed magnetic circuit; and the second side column magnetic conductor and the center magnetic conductor form a clockwise closed magnetic circuit.

8. The integrated common-mode inductor as described in claim 1, wherein the polarity of the first winding, which exits from the same side of the second column magnetic conductor, is the same as the polarity of the second winding and the polarity of the third winding.

9. A switching power converter, comprising: A transformer has a primary side and a secondary side; and a primary-side circuit coupled to the primary side, the primary-side circuit including: a power supply impedance stabilization network receiving an input power supply; a noise cancellation circuit including: a first capacitor; the integrated common-mode inductor as claimed in any one of claims 1 to 8, coupled to the first capacitor; and a second capacitor coupled to the integrated common-mode inductor; and a voltage conversion circuit coupled between the integrated common-mode inductor and the primary side.

10. The switching power converter as claimed in claim 9, wherein the first capacitor is coupled between the output side of the power impedance stabilization network and the input side of the integrated common-mode inductor.

11. The switching power converter as claimed in claim 10, wherein the first capacitor is coupled between the second end of the first winding and the second end of the second winding and the second end of the third winding.

12. The switching power converter as claimed in claim 10, wherein the first capacitor is coupled between an extension of the first winding and between the second end of the second winding and the second end of the third winding.

13. The switching power converter as claimed in claim 9, wherein the second end of the second winding is coupled to the second end of the third winding, and a first end of the second capacitor is coupled to the first end of the third winding, and a second end of the second capacitor is coupled to ground.

14. The switching power converter as claimed in claim 9, wherein the first end of the second winding is coupled to the first end of the third winding, and a first end of the second capacitor is coupled to the second end of the third winding, and a second end of the second capacitor is coupled to ground.

15. The switching power converter as claimed in claim 9, wherein the third winding generates a reverse current equivalent to a common-mode noise current.

16. The switching power converter as claimed in claim 9, wherein the noise cancellation circuit has the function of a current converter.

17. The switching power converter as claimed in claim 16, wherein the noise cancellation circuit further functions as a signal amplifier and / or signal converter.

18. The switching power converter as claimed in claim 9, wherein the primary-side circuitry further comprises: A protection circuit is coupled to the primary side of the transformer.

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