CN103208974A - Differential-mode and common-mode capacitance integration module for high-power plane electro-magnetic interference (EMI) filter - Google Patents

Abstract

The invention discloses a differential common-mode capacitor integrated module for high-power planar EMI filters, including a common-mode attenuator, a differential-mode attenuator, a U-shaped copper strip I and a U-shaped copper strip II; the U-shaped copper strip The two long arms of bar I are respectively connected to the two long arms of U-shaped copper bar II through a differential mode attenuator, and the two long arms of U-shaped copper bar I and U-shaped copper bar II are respectively installed with a common mode attenuator. It can be seen that the present invention only covers the attenuator on the two long arms of the U-shaped copper strip, and the copper strip at the U-shaped arc is not covered with anything, so that the electromagnetic coupling between the attenuator modules becomes simple, and at the same time Since the U-shaped structure is used, the problem of uneven current distribution at the corners existing in the three-section structure can be effectively improved.

Description

Differential Common Mode Capacitor Integrated Module for High Power Planar EMI Filter

technical field

The invention relates to a differential common-mode capacitance integrated module used for a high-power planar EMI filter.

Background technique

EMI filter is an important means to suppress conducted electromagnetic interference in switching power supply. In distributed power system, general EMI filter accounts for 15%~20% of the entire front-end converter. With the trend of miniaturization of power electronic systems, front-end converter With the continuous reduction of volume, the volume of EMI filter also needs to be continuously reduced. The integration of EMI filters conforms to the development trend of miniaturization and integration of power electronic systems. By consulting relevant literature, we found that the integration of EMI filters mainly includes the integration of differential and common mode inductors; the integration of common mode inductors and common mode capacitors; the integration of differential mode inductors and common mode capacitors. However, these integrated filters also have to withstand high power energy while filtering in the circuit, making it difficult to develop integrated filters in the direction of high power. In response to these problems, CPES proposed a linear RF filter, which is composed of a common mode attenuation module, a copper strip, and a differential mode attenuation module. The power current flows in the copper strip, and the noise current is attenuated in the common mode and differential mode. The flow through the module realizes the separation of power current and noise current. The cross-sectional area of the copper strip can be relatively large, so that the entire filter can withstand a large amount of power energy. The entire filter presents low resistance to the 50Hz power current and is relatively The high-frequency noise current presents a very high impedance, but using this structure to achieve the target common-mode and differential-mode capacitance values requires a long module, which is not conducive to the miniaturization and integration of the filter. In response to this, CPES further proposes a three-segment filter, which is equivalent to bending the previous linear filter into three segments, and the segments are connected at right angles. This structure can effectively solve the length problem of the linear filter. However, the structural sections are connected at right angles, and the current distribution at the right-angle corners is very uneven, which seriously affects the performance of the filter. At the same time, due to the short distance between the three sections with the same structure, the electromagnetic field Coupling gets complicated.

Contents of the invention

和U形铜条

的长臂之间覆着差模衰减器，在U形铜条

的两个长臂下方覆着共模衰减器。该结构中只在U形铜条的两个长臂上覆着衰减器，U形弧度处的铜条不覆着任何东西，使得衰减器模块之间的电磁耦合变得简单，同时由于使用的是U形结构，可有效的改善三段式结构中存在的拐角处电流分布不均匀的问题。 Aiming at the deficiencies in the prior art, the present invention provides a differential common-mode capacitor integrated module for high-power planar EMI filters. The differential common-mode capacitor integrated module uses two U-shaped copper strips as substrates, and the U-shaped copper strips A common mode attenuator is covered above the two long arms of the U-shaped copper bar

and U-shaped copper bars

The long arms are clad with differential mode attenuators, the U-shaped copper strips

The common mode attenuator is covered under the two long arms of the . In this structure, the attenuator is only covered on the two long arms of the U-shaped copper strip, and the copper strip at the U-shaped radian is not covered with anything, which makes the electromagnetic coupling between the attenuator modules simple, and at the same time due to the use of It is a U-shaped structure, which can effectively improve the problem of uneven current distribution at the corners existing in the three-stage structure.

The present invention adopts following technical scheme in order to realize above-mentioned invention object:

A kind of differential common-mode capacitor integrated module for high-power planar EMI filter, comprises common-mode attenuator, differential mode attenuator, U-shaped copper bar I and U-shaped copper bar II; The two of described U-shaped copper bar I The two long arms are respectively connected to the two long arms of the U-shaped copper strip II through a differential mode attenuator, and a common-mode attenuator is respectively installed on the outside of the two long arms of the U-shaped copper strip I and the U-shaped copper strip II .

The common mode attenuator includes a ceramic plate I and nickel layers stacked on both sides of the ceramic plate I.

Ceramic plate 1 adopts N1250 material to make.

The common mode attenuator includes a ceramic plate II and nickel layers covering both sides of the ceramic plate II.

The ceramic plate II is made of BaTiO ₃ material.

According to the above technical scheme, corresponding to the prior art, the present invention has the following beneficial effects:

During use, the power current of 50Hz flows through the copper bar, the high-frequency common-mode noise current flows through the common-mode attenuator, and the high-frequency differential-mode noise current flows through the differential-mode attenuator. The differential common-mode capacitor integrated module realizes that the 50Hz power current and the high-frequency noise current flow through different paths, and presents a low impedance to the 50Hz power current and a very high impedance to the high-frequency noise current, thereby realizing the filtering function; in addition , the present invention only covers the attenuator on the two long arms of the U-shaped copper bar, and the copper bar at the U-shaped arc is not covered with anything, so that the electromagnetic coupling between the attenuator modules becomes simple, and at the same time due to the use of It is a U-shaped structure, which can effectively improve the problem of uneven current distribution at the corners existing in the three-stage structure.

Description of drawings

Fig. 1 is an exploded view of the differential common mode capacitor integrated module of the present invention;

Fig. 2 is the sectional view of common mode attenuator described in Fig. 1;

Figure 3 is a sectional view of the differential mode attenuator described in Figure 1;

Fig. 4 is the connection diagram of the differential common mode capacitor integrated module of the present invention;

Fig. 5 is the electric current distributing figure of differential common-mode capacitor integrated module of the present invention; Wherein: what Fig. 5 a shows is the schematic diagram that the electric current of 50Hz flows through in the copper bar of low impedance; What Fig. 5 b shows is that high-frequency common-mode current flows from A schematic diagram of the common mode attenuator located on both sides of the copper strip; Figure 5c shows a schematic diagram of the differential mode current flowing through the differential mode attenuator between the copper strips;

In Fig. 1-3: 201, the first common mode attenuator I; 202, the second common mode attenuator I; 203, U-shaped copper bar I; 204, the first differential mode attenuator; 205, the second differential mode attenuator 206, U-shaped copper strip II; 207, the first common mode attenuator II; 208, the second common mode attenuator II; 209, the nickel layer I of the common mode attenuator; 210, the ceramic plate of the common mode attenuator I; 211, the nickel layer II of the common mode attenuator; 212, the nickel layer I of the differential mode attenuator; 213, the ceramic plate II of the differential mode attenuator; 214, the nickel layer II of the differential mode attenuator;

In Fig. 4 and Fig. 5: V _in is an input terminal; V _out is an output terminal.

Detailed ways

The accompanying drawings disclose, without limitation, the structural schematic diagrams of the preferred embodiments involved in the present invention; the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings.

The differential common-mode capacitance integrated module for high-power planar EMI filter of the present invention, as shown in Figure 1, comprises the first common-mode attenuator I201, the second common-mode attenuator I202, U-shaped copper bar I203, The first differential mode attenuator 204, the second differential mode attenuator 205, the U copper bar II206, the first common mode attenuator II207, and the second common mode attenuator II208.

Among them, the structures of the first common mode attenuator I201, the second common mode attenuator I202, the first common mode attenuator II207 and the second common mode attenuator II208 are consistent, as shown in FIG. The nickel layers 209, 211 on both sides of the ceramic plate I210; the ceramic plate I is made of N1250 material.

The first differential mode attenuator 204 and the second differential mode attenuator 205 have the same structure, as shown in FIG. Made of BaTiO ₃ material.

The connection diagram of each component in the differential common-mode capacitance integrated module of the present invention, as shown in Figure 4: the nickel layer II211 of the second common-mode attenuator I202 and a long arm of the U-shaped copper strip I203 and the second differential mode attenuation The nickel layer I212 of the device 205 is connected together as an input terminal of the circuit. The nickel layer II214 of the second differential mode attenuator 205 is connected with the U copper bar II206 and the second common mode attenuator II208 together as another input terminal of the circuit. The nickel layer II211 of the first common mode attenuator I201 is connected with a long arm of the U-shaped copper strip I203 and the nickel layer I212 of the first differential mode attenuator 204 as an output terminal of the circuit. The nickel layer II214 of the first differential mode attenuator 204 is connected with the U copper strip II206 and the nickel layer I212 of the first common mode attenuator II207 as another output terminal of the circuit. The nickel layer I209 of the first common mode attenuator I201 and the second common mode attenuator I202 and the nickel layer II211 of the first common mode attenuator II207 and the second common mode attenuator II208 are respectively grounded.

As shown in Figure 5, when a 50Hz alternating current is applied to the structure, since the resistance of the copper layer is much smaller than that of the nickel layer, the 50Hz current flows through the low-impedance copper strip (Figure 5a). When a high-frequency common-mode current flows through this structure, the skin effect is obvious due to the high frequency of the common-mode current. At this time, because the resistance of the nickel layer is weaker than the skin effect, the role of the skin effect Next, the high-frequency common-mode current passes through the common-mode attenuator located on both sides of the copper strip (Fig. 5b). Due to the high resistivity of the nickel layer and the low skin depth of the nickel layer, the noise current passes through the common-mode attenuator. be attenuated. When the high-frequency differential mode current passes through this structure, the proximity effect is obvious at this time due to the high frequency of the differential mode current. Flow through the mode attenuator (Figure 5c), and the differential mode current is also attenuated due to the high resistivity of the nickel layer.

The common-mode attenuator in this structure can be simplified as an RC filter. When only the influence of the skin effect on the resistance is considered, the resistance of the attenuator is:

是镍的电阻率，

是镍层的厚度，

是镍的集肤深度，

是镍层的宽度。 in

is the resistivity of nickel,

is the thickness of the nickel layer,

is the skin depth of nickel,

is the width of the nickel layer.

The capacitance of the common mode attenuator:

是空气的介电常数，

是共模衰减器中陶瓷板N1250的介电常数，

是共模衰减器中陶瓷板的厚度，

是镍层的面积。 in

is the dielectric constant of air,

is the dielectric constant of the ceramic plate N1250 in the common mode attenuator,

is the thickness of the ceramic plate in the common mode attenuator,

is the area of the nickel layer.

The differential-mode attenuator in this structure can also be simplified as an RC filter, and its resistance value is consistent with the resistance value algorithm in the above-mentioned common-mode attenuator. The capacitance value is:

是差模衰减器中陶瓷板BaTiO₃的介电常数，

是镍层的面积，

是差模衰减器中陶瓷板的厚度，

是镍层的面积。 in, is the dielectric constant of air,

is the dielectric constant of the ceramic plate _BaTiO3 in the differential mode attenuator,

is the area of the nickel layer,

is the thickness of the ceramic plate in the differential mode attenuator,

is the area of the nickel layer.

Through the connection as shown in Figure 4, this structure realizes the integration of differential common mode capacitors.

Claims (5)

1. a kind of differential common-mode capacitor integrated module for high-power planar EMI filter, comprises common-mode attenuator, differential mode attenuator, is characterized in that: also comprise U-shaped copper bar I and U-shaped copper bar II; The two long arms of the U-shaped copper strip I are respectively connected to the two long arms of the U-shaped copper strip II through a differential mode attenuator, and the outer sides of the two long arms of the U-shaped copper strip I and the U-shaped copper strip II A common mode attenuator is installed respectively. 2. The differential common-mode capacitor integrated module for high-power planar EMI filter according to claim 1, characterized in that: said common-mode attenuator comprises a ceramic plate 1 and a nickel layer stacked on both sides of the ceramic plate 1. 3. according to claim 2, is used for the differential common-mode capacitance integrated module of high-power planar EMI filter, it is characterized in that: ceramic plate 1 adopts N1250 material to make. 4. The differential common-mode capacitor integrated module for high-power planar EMI filter according to claim 1, characterized in that: said common-mode attenuator comprises a ceramic plate II and nickel layers covering both sides of the ceramic plate II. 5. The differential common-mode capacitor integrated module for high-power planar EMI filter according to claim 4, characterized in that: said ceramic board II is made of BaTiO ₃ material.

Images