阅读说明：本技术 一种用于抑制emi的低电感差共模集成的卷绕式电容器 (Low-inductance difference and common-mode integrated winding capacitor for inhibiting EMI ) 是由 郑峰 王安宇 高天 武志强 于 2021-06-11 设计创作，主要内容包括：本发明提出了一种用于抑制EMI的低电感差共模集成的卷绕式电容器,可用于电力电子系统的直流侧。电容器包括两端开口的筒状金属外壳(1)和位于其筒腔中至少卷绕两圈的卷绕层(2),以及外壳(1)的两个端口处绝缘固定的金属极板(3)和接地金属极板(4)。与现有技术相比,本发明在卷绕层中设置有接地箔,利用互感相消的原理减小电容器的寄生电感,提高电容的高频噪声抑制能力。此外,卷绕层中阴极箔、阳极箔、接地箔与共模电介质层组成了共模电容,阴极箔、阳极箔与差模电介质层组成了差模电容,实现了将共模电容与差模电容集成在一个元件中,减少元件数目,从而减小体积占用。(The invention provides a low-inductance difference common-mode integrated winding capacitor for inhibiting EMI, which can be used on the direct current side of a power electronic system. The capacitor comprises a cylindrical metal shell (1) with openings at two ends, a winding layer (2) which is positioned in a cylinder cavity of the cylindrical metal shell and is wound for at least two circles, and a metal pole plate (3) and a grounding metal pole plate (4) which are fixed at two ports of the shell (1) in an insulating mode. Compared with the prior art, the grounding foil is arranged in the winding layer, the parasitic inductance of the capacitor is reduced by utilizing the principle of mutual inductance cancellation, and the high-frequency noise suppression capability of the capacitor is improved. In addition, the cathode foil, the anode foil, the grounding foil and the common-mode dielectric layer in the winding layer form a common-mode capacitor, and the cathode foil, the anode foil and the differential-mode dielectric layer form a differential-mode capacitor, so that the common-mode capacitor and the differential-mode capacitor are integrated in one element, the number of the elements is reduced, and the volume occupation is reduced.)

1. A low-inductance difference common-mode integrated winding capacitor for inhibiting electromagnetic interference (EMI) is characterized by comprising a cylindrical metal shell (1) with two open ends and a winding layer (2) which is positioned in a cylinder cavity of the metal shell and is wound for at least two turns; the winding layer (2) comprises a first differential mode dielectric layer (21), a first common mode dielectric layer (22), a second common mode dielectric layer (23) and a second differential mode dielectric layer (24) which are sequentially stacked; a cathode foil (25) is arranged between the first differential mode dielectric layer (21) and the first common mode dielectric layer (22); a grounding foil (26) is arranged between the first common mode dielectric layer (22) and the second common mode dielectric layer (23) and is used for reducing the parasitic inductance of the capacitor; an anode foil (27) is arranged between the second common mode dielectric layer (23) and the second differential mode dielectric layer (24); a metal polar plate (3) and a grounding metal polar plate (4) are respectively fixed at two ports of the shell (1) in an insulating manner, the metal polar plate (3) of each port is fixed with the grounding metal polar plate (4) in an insulating manner, one metal polar plate (3) is connected with a cathode foil (25) in a multi-point manner, the other metal polar plate (3) is connected with an anode foil (27) in a multi-point manner, and the two grounding metal polar plates (4) are connected with a grounding foil (26) in a multi-point manner;

the first differential mode dielectric layer (21) and the second differential mode dielectric layer (24) are made of the same dielectric material, and the first common mode dielectric layer (22) and the second common mode dielectric layer (23) are made of the same dielectric material;

when the metal pole plate (3) connected with the anode foil (27) and the metal pole plate (3) connected with the cathode foil (25) are loaded between a positive bus and a negative bus of a direct-current power supply respectively, the cathode foil (25), the first common-mode dielectric layer (22) and the grounding foil (26) jointly form a common-mode capacitance of a negative pole to the ground, the grounding foil (26), the second common-mode dielectric layer (23) and the anode foil (27) jointly form a common-mode capacitance of a positive pole to the ground, and the cathode foil (25), the first differential-mode dielectric layer (21), the second differential-mode dielectric layer (24) and the anode foil (27) jointly form a differential-mode capacitance between the positive pole and the negative pole, so that the differential-common-mode integration characteristic of the capacitor is realized.

2. A low inductance differential-common mode integrated wound capacitor for rejection of electromagnetic interference, EMI, according to claim 1, characterized in that the winding layer (2), of which the cathode foil (25) and the anode foil (27) connected to the two metal plates (3) and the ground foil (26) connected to the two grounded metal plates (4), has a dimension H in height direction that is larger than the height dimensions of the first differential mode dielectric layer (21), the first common mode dielectric layer (22), the second common mode dielectric layer (23) and the second differential mode dielectric layer (24).

Technical Field

The invention belongs to the technical field of power electronics, relates to a winding capacitor, and particularly relates to a low inductance difference common mode integrated winding capacitor for inhibiting direct current side electromagnetic interference (EMI) of a power electronic system.

Background

In a power electronic system, the fast turn-on and turn-off of a switching device can generate broadband and high-energy electromagnetic interference, and is an important interference source in the system. Electromagnetic interference generated by the switching device can be transmitted along a power supply line to form conducted interference, so that the stability and safety of power supply equipment are influenced, and the normal work of a load is influenced. Meanwhile, the electromagnetic noise contains abundant frequency spectrum components, the high-frequency noise can also radiate electromagnetic interference outwards, and electronic equipment which is sensitive to electromagnetic radiation, such as an acquisition control system, radio communication equipment and navigation positioning equipment, is extremely easy to be influenced by external electromagnetic radiation.

The problem of electromagnetic compatibility between electrical and electronic products has attracted much attention, and many countries and organizations have established a series of standards for electromagnetic compatibility, and only products meeting the standards can enter the market, which requires suppression of electromagnetic interference in power and electronic systems. The capacitor element can construct a low-impedance path in a circuit to realize a filtering function, so that the capacitor element is widely applied to the occasions of EMI suppression. EMI is divided into differential mode noise and common mode noise, and correspondingly, the capacitor used for filtering is also divided into differential mode capacitance and common mode capacitance. The capacitance connected across the positive and negative bus bars to suppress the differential mode noise is referred to as a differential mode capacitance, and the capacitance connected between the single line and the ground to suppress the common mode noise is referred to as a common mode capacitance.

The capacitor in practical use is not ideal capacitance, and inevitably has parasitic inductance due to a structural limitation thereof, and if the parasitic inductance is high, a high voltage spike is formed even if the frequency of the flowing current is low, and the noise current generally contains a large amount of high frequency components, so that the capacitor with high parasitic inductance is unacceptable for suppressing EMI. Since the winding type capacitor is manufactured by winding, inductance is generally low, and for example, patent application publication No. CN107424843A entitled "low inductance capacitor" discloses a winding type low inductance capacitor in which a capacitor film is wound around a region between a first wound conductive layer and a second wound conductive layer to reduce parasitic inductance by a winding type structure. Although the invention can play a good role in inhibiting low-frequency noise, only two conductor layers are arranged in the winding layer, the effect of inhibiting parasitic inductance is limited, the attenuation capability of high-frequency noise is insufficient, and the requirement of EMI inhibition cannot be met.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a low-inductance differential-common mode integrated winding capacitor for suppressing EMI, which is intended to reduce parasitic inductance of the capacitor and to achieve miniaturization.

In order to achieve the purpose, the invention adopts the technical scheme that:

a low inductance difference common mode integrated winding type capacitor for suppressing electromagnetic interference EMI comprises a cylindrical metal shell 1 with openings at two ends and a winding layer 2 which is positioned in a cylinder cavity of the metal shell and is wound for at least two turns; the winding layer 2 comprises a first differential mode dielectric layer 21, a first common mode dielectric layer 22, a second common mode dielectric layer 23 and a second differential mode dielectric layer 24 which are sequentially stacked, a cathode foil 25 is arranged between the first differential mode dielectric layer 21 and the first common mode dielectric layer 22, a grounding foil 26 is arranged between the first common mode dielectric layer 22 and the second common mode dielectric layer 23 and used for reducing parasitic inductance of the capacitor, and an anode foil 27 is arranged between the second common mode dielectric layer 23 and the second differential mode dielectric layer 24; a metal polar plate 3 and a grounding metal polar plate 4 are respectively fixed at two ports of the shell 1 in an insulating manner, the metal polar plate 3 of each port is fixed with the grounding metal polar plate 4 in an insulating manner, one metal polar plate 3 is connected with a cathode foil 25 in a multi-point manner, the other metal polar plate 3 is connected with an anode foil 27 in a multi-point manner, and the two grounding metal polar plates 4 are connected with a grounding foil 26 in a multi-point manner;

the first differential mode dielectric layer 21 and the second differential mode dielectric layer 24 are made of the same dielectric material, and the first common mode dielectric layer 22 and the second common mode dielectric layer 23 are made of the same dielectric material;

when the metal plate 3 connected with the anode foil 27 and the metal plate 3 connected with the cathode foil 25 are loaded between positive and negative buses of a direct-current power supply respectively, the cathode foil 25, the first common-mode dielectric layer 22 and the grounding foil 26 jointly form a common-mode capacitance of a negative electrode to the ground, the grounding foil 26, the second common-mode dielectric layer 23 and the anode foil 27 jointly form a common-mode capacitance of a positive electrode to the ground, and the cathode foil 25, the first differential-mode dielectric layer 21, the second differential-mode dielectric layer 24 and the anode foil 27 jointly form a differential-mode capacitance between the positive electrode and the negative electrode, so that the differential-common-mode integration characteristic of the capacitor is realized.

In the winding type capacitor for low inductance difference common mode integration for suppressing electromagnetic interference (EMI), the winding layer 2, the cathode foil 25 and the anode foil 27 connected with the two metal plates 3, and the grounding foil 26 connected with the two grounding metal plates 4 have a dimension H in the height direction larger than the height dimension of the housing 1.

Compared with the prior art, the invention has the following advantages:

1. according to the invention, the cathode foil is arranged between one differential mode dielectric layer and one common mode dielectric layer in the winding layer, the anode foil is arranged between the other differential mode dielectric layer and the other common mode dielectric layer, the grounding foil is arranged between the two common mode dielectric layers, the current direction in the grounding foil is opposite to the current direction in the anode foil and the cathode foil on the two sides, the mutual inductance cancellation of the inductance is realized, the parasitic inductance of the capacitor is lower, and the conductive metal foil and the polar plate of the winding layer are connected in a multi-point mode, so that the current path is shortened, the parasitic inductance is further reduced, and compared with the prior art, the suppression capability of high-frequency noise is effectively improved.

2. The winding layer grounding foil forms a common-mode capacitor with the common-mode dielectrics among the anode foil, the cathode foil and the metal foil respectively, after winding, the cathode foil, the anode foil and the dielectrics among the cathode foil and the anode foil form a differential-mode capacitor, so that the differential-mode capacitor and the common-mode capacitor are integrated in the same capacitor, compared with the prior art, the capacitor has the advantages that the size is reduced, and the miniaturization is realized.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of the unrolled configuration of the wrapped layers of the invention;

fig. 3 is a schematic perspective view of a wound layer of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

Referring to fig. 1, the present invention includes a cylindrical metal case 1 opened at both ends and a winding layer 2 wound at least two times in a cylindrical cavity thereof.

The shell 1 of the present embodiment is made of an aluminum alloy material in consideration of the weight, mechanical strength, cost, and other factors.

The structure of the winding layer 2 is as shown in fig. 2 and fig. 3, and includes a first differential mode dielectric layer 21, a first common mode dielectric layer 22, a second common mode dielectric layer 23, and a second differential mode dielectric layer 24, which are sequentially stacked, a cathode foil 25 is disposed between the first differential mode dielectric layer 21 and the first common mode dielectric layer 22, a grounding foil 26 is disposed between the first common mode dielectric layer 22 and the second common mode dielectric layer 23 for reducing parasitic inductance of a capacitor, and an anode foil 27 is disposed between the second common mode dielectric layer 23 and the second differential mode dielectric layer 24; a metal polar plate 3 and a grounding metal polar plate 4 are respectively fixed at two ports of the shell 1 in an insulating manner, the metal polar plate 3 of each port is fixed with the grounding metal polar plate 4 in an insulating manner, one metal polar plate 3 is connected with a cathode foil 25 in a multi-point manner, the other metal polar plate 3 is connected with an anode foil 27 in a multi-point manner, and the two grounding metal polar plates 4 are connected with a grounding foil 26 in a multi-point manner. The dimension of the winding layer 2 in the height direction, in which the cathode foil 25 and the anode foil 27 connected to the two metal plates 3 and the ground foil 26 connected to the two ground metal plates 4 are larger than the height dimensions of the first differential mode dielectric layer 21, the first common mode dielectric layer 22, the second common mode dielectric layer 23 and the second differential mode dielectric layer 24, is larger than that of the first differential mode dielectric layer 22.

The cathode foil 25 extends at one end of the cylinder, the part which is larger than four layers of dielectric layers in the height direction is connected with the metal pole plate 3 in a multi-point connection mode, the anode foil 27 extends at the other end of the cylinder, the part which is larger than four layers of dielectric layers in the height direction is connected with the metal pole plate 3 at the end, the grounding foil 26 extends towards two ends, and the part which is larger than four layers of dielectric layers in the height direction is connected with the grounding metal pole plate 4.

The first differential mode dielectric layer 21 and the second differential mode dielectric layer 24 are made of the same dielectric material, and the first common mode dielectric layer 22 and the second common mode dielectric layer 23 are made of the same dielectric material;

most of the capacitors can be regarded as a modification of a parallel plate capacitor model, the four dielectric layers are dielectric materials between two plates in the capacitor model, the dielectric materials must have insulating properties, and high dielectric constant and low energy loss materials are preferably selected, and polyethylene terephthalate (PET) is used as the dielectric material in the embodiment. The three layers of metal foils are polar plates for storing charges in the capacitor model, the metal foils are all equipotential bodies and are required to have good conductivity, the conductivity and the cost are comprehensively considered, in the embodiment, the aluminum foil is used, and the metal polar plates and the grounding metal plate are aluminum polar plates.

The winding layer 2 is wound at least twice, when the metal plate 3 connected with the anode foil 27 and the metal plate 3 connected with the cathode foil 25 are loaded between a positive bus and a negative bus of a direct-current power supply respectively, the cathode foil 25, the first common-mode dielectric layer 22 and the grounding foil 26 jointly form a common-mode capacitance of a negative electrode to the ground, the grounding foil 26, the second common-mode dielectric layer 23 and the anode foil 27 jointly form a common-mode capacitance of a positive electrode to the ground, and the cathode foil 25, the first differential-mode dielectric layer 21, the second differential-mode dielectric layer 24 and the anode foil 27 jointly form a differential-mode capacitance between the positive electrode and the negative electrode, so that the differential-mode integration characteristic of the capacitor is realized.

When the capacitor is wound, the first differential mode dielectric layer 21 is positioned on the inner side, the second differential mode dielectric layer 24 is positioned on the outer side, after at least two turns of winding, the cathode foil 25 and the first differential mode dielectric layer 21 positioned on the inner side of the outer ring, the second differential mode dielectric layer 24 and the anode foil 27 positioned on the outer side of the inner ring form a differential mode capacitor together, if the winding is less than two turns, the differential mode capacitor cannot be formed, and the capacitor loses the differential mode characteristic. Due to the difference and common mode integration characteristics of the capacitor, the difference mode capacitance and the common mode capacitance which need to be configured independently in the original power electronic system can be replaced by the difference and common mode integrated capacitance, so that the using number of elements is reduced, and the volume occupied by the capacitor is reduced on the whole.

The working principle of the invention is as follows:

the invention utilizes the principle of inductance mutual inductance cancellation, and the grounding layer is arranged in the winding layer, so that the current in the grounding layer flows to the grounding metal polar plates at two ends, and the current direction in the grounding layer is respectively opposite to the current direction in the anode foil and the cathode foil, thereby canceling the inductance and reducing the parasitic inductance. When the capacitor is loaded between a positive bus and a negative bus of a direct-current power supply, the cathode foil, the anode foil, the grounding foil and the dielectric medium between the cathode foil, the anode foil and the dielectric medium between the cathode foil and the anode foil form a differential mode capacitor together after winding, so that the differential mode and common mode integration of the capacitor is skillfully realized, and the volume is reduced.

The foregoing description is only an example of the present invention and should not be construed as limiting the invention, as it will be apparent to those skilled in the art that various modifications and variations in form and detail can be made without departing from the principle and structure of the invention after understanding the present disclosure and the principles, but such modifications and variations are considered to be within the scope of the invention.