CN104270111A - A bus-type EMI filter with common-mode inductance enhancement structure - Google Patents

Abstract

The invention discloses a bus type EMI (Electro-Magnetic Interference) filter having a common-mode inductance enhancing structure. The bus type EMI filter comprises a linear capacitance bus integrated module, a U-shaped magnetic core, an I-shaped magnetic core and a coil, wherein the linear capacitance bus integrated module comprises six layers of nickel, three layers of high-dielectric-constant materials and two layers of copper which are stacked according to a certain sequence, so that a bus and differential-mode and common-mode capacitors are integrated; two magnetic columns of the U-shaped magnetic core are wound with symmetrically-wound coils, and a whole magnetic circuit is enclosed through the I-shaped magnetic core, thereby constructing a common-mode inductor; a differential-mode inductor is constructed by a leakage inductor; and the whole structure sleeves the linear capacitance bus integrated module. Compared with a conventional EMI filter, the bus type EMI filter has the advantages that the EMI filter is combined with the bus, so that space is saved; through an integrated structure, influences of parasitic parameters are reduced; and an EMI filter scheme which can be applied to high power density and has excellent high-frequency performance is provided.

Description

A bus-type EMI filter with common-mode inductance enhancement structure

technical field

The invention relates to the field of electronic technology, in particular to a busbar type EMI filter. the

Background technique

The EMI filter is one of the effective means to suppress the conduction electromagnetic interference of the switching power supply. With the continuous improvement of the operating frequency and power density of the power converter, the power converter is developing in the direction of miniaturization, integration and high frequency, which puts forward higher requirements for the volume and performance of the EMI filter. Traditional discrete EMI filter inductors and capacitors are placed separately, with low space utilization, large parasitic parameters, and poor high-frequency performance. Therefore, the integration of EMI filters has become a future development trend. the

At present, the Center for Power Electronics System (CPES) in the United States has a core position in research in this field, and to a certain extent represents the mainstream direction of research in the field of power electronics integration. CPES once proposed a planar EMI filter based on a rectangular "inductance-capacitance" (LC) integrated module. However, in the rectangular LC integrated module, the current is unevenly distributed at the right-angled corner of the wire, which affects the performance of the filter. It also makes it unsuitable for high-power applications. Later, people proposed the planar EMI filter of the ring-shaped LC integrated module, which effectively solved the problem of uneven current distribution at the right-angled corner of the wire. However, in order to provide sufficient common-mode inductance, the entire LC integrated module is placed in a pot-shaped magnetic core It is not conducive to the dissipation of heat, and it is not suitable for high-power occasions. In order to adapt to high-power occasions, CPES proposes a bus-type EMI filter that combines the bus and EMI filters. On the basis of the bus, multi-layer materials are laminated to realize capacitor integration. However, due to the linear structure of the bus, etc. The effective number of turns is 1 turn, and the common-mode inductance is difficult to meet the requirements. On this basis, some people propose to put multiple magnetic cores on the outside to increase the common-mode inductance. However, on the one hand, multiple magnetic cores will increase the busbar type. EMI filter space volume, on the other hand, because the number of turns is 1 turn, the increase in common mode inductance is limited after the magnetic core is put on. It is difficult to meet the requirements of common mode inductance for power electronic equipment with large common mode interference, which limits its application. scope. the

On this basis, the research group proposes a new type of bus-type EMI filter, which can well integrate common-mode inductors, making the bus-type EMI filter suitable for more occasions. the

Contents of the invention

The technical problem to be solved by the present invention is to provide a bus-type EMI filter that provides relatively large drop-off and common-mode inductance against the defects of the background technology, which can be applied to a wider range of power converters. the

The present invention adopts the following technical solutions for solving the problems of the technologies described above:

A bus-type EMI filter with a common-mode inductance enhancement structure, including a linear capacitor-bus integration module and a coil core inductance module, wherein:

The coil magnetic core inductance module is composed of a U-shaped magnetic core, a first coil, a second coil and an I-shaped magnetic core. On the magnetic column; the U-shaped magnetic core and the I-shaped magnetic core form a closed magnetic circuit;

One port of the first coil and one port of the second coil are respectively connected to two bus ports at one end of the linear capacitor bus integrated module; the two bus ports at the other end of the linear capacitor bus integrated module are connected to the first coil Another port of 103 and another port of the second coil form the input/output port of the busbar type EMI filter;

The inductance of the coil magnetic core inductance module is a common mode inductance, and the leakage inductance is a differential mode inductance;

The coil magnetic core inductance module is sleeved on the linear capacitor bus integrated module. the

As a further optimization scheme of the bus-type EMI filter with a common-mode inductance enhancement structure of the present invention, the linear capacitor-bus integrated module includes 11 layers of material structures, and the layers from the first layer to the eleventh layer are: the first nickel layer, the first high dielectric constant material layer, the second nickel layer, the first copper layer, the third nickel layer, the second high dielectric constant material layer, the fourth nickel layer, the second copper layer, the fifth nickel layer, The third high dielectric constant material layer, the sixth nickel layer, the whole structure is symmetrical with the second high dielectric constant material layer of the sixth layer;

The first copper layer and the second copper layer are busbars conducting the working current;

The first nickel layer, the first high dielectric constant material layer, and the second nickel layer form a common-mode capacitor;

The fifth nickel layer, the third high dielectric constant material layer, and the sixth nickel layer form a common-mode capacitor;

The third nickel layer, the second high dielectric constant material layer, and the fourth nickel layer form a differential mode capacitor;

The first nickel layer and the sixth nickel layer are grounded during operation. the

As a further optimization scheme of the bus-type EMI filter with a common-mode inductance enhancement structure of the present invention, the respective high dielectric constant material layers are made of ceramic materials. the

As a further optimization scheme of the bus-type EMI filter with a common mode inductance enhancement structure of the present invention, the ceramic material is BaTiO ₃ or CaCu ₃ Ti ₄ O ₁₂ .

Compared with the prior art by adopting the above technical scheme, the present invention has the following technical effects:

1. Different from the traditional EMI filter and busbar placed separately, this research group proposes a busbar-type EMI filter that combines EMI filter and busbar, which can reduce the volume and increase the power density;

2. Winding the coil on the jacket magnetic core can effectively increase the inductance and make up for the defect of insufficient inductance of the linear structure, so that it can meet the design requirements of various power converters. the

Description of drawings

Fig. 1 is a structural assembly drawing of busbar type EMI filter of the present invention;

Fig. 2 is a linear structural sectional view in the busbar type EMI filter of the present invention;

Fig. 3 is the wiring diagram of busbar type EMI filter of the present invention;

Fig. 4 is a schematic circuit diagram of a bus-type EMI filter of the present invention. the

In the figure, 101 is a U-shaped magnetic core, 102 is a linear capacitor bus integration module, 103 is a first coil, 104 is a second coil, 105 is an I-shaped magnetic core, 201, 203, 205, 207, 209, and 211 are respectively are the first to sixth nickel layers, 202, 206, and 210 are the first to third high dielectric constant material layers respectively, 204 is the first copper layer, 208 is the second copper layer, 301, 302 are the first coil 305 and 306 are the two ports of the second coil, and 303, 304, 307 and 308 are the four ports of the linear capacitor bus integrated module. the

Detailed ways

Below in conjunction with accompanying drawing technical scheme of the present invention is described in further detail:

As an example shown in Figure 1, the present invention discloses a bus-type EMI filter with a common-mode inductance enhancement structure, including a linear capacitor bus integration module 102, and a coil core inductor module, wherein the coil core inductor The module is composed of a U-shaped magnetic core 101, a first coil 103, a second coil 104 and an I-shaped magnetic core 105. The first coils 103, 104 wind in the same direction and are set on the two magnetic columns of the U-shaped magnetic core 101; the whole The inductance of the coil magnetic core inductance module is a common mode inductance, and the leakage inductance is a differential mode inductance. the

Figure 2 is a cross-sectional view of the multi-layer structure of the linear capacitor bus integration module. The multilayer structure from top to bottom is nickel 201, ceramic 202, nickel 203, copper 204, nickel 205, ceramic 206, nickel 207, copper 208, nickel 209, ceramic 210, nickel 211. The bus bars are copper 204 and copper 208, and nickel 201 and nickel 211 are grounded. In order to simplify the design, the dimensions of the same material are consistent throughout the structure. When the high-frequency electromagnetic interference signal and the working current flow in from the busbar, according to the skin effect, the high-frequency interference current in a single busbar tends to flow through the nickel layers on both sides, and according to the proximity effect, the high-frequency interference current in the two busbars flows through The high-frequency interference current tends to flow through the nickel layer between them. Since the resistivity of nickel is greater than that of copper, the high-frequency interference signal will be more easily converted into heat in the nickel layer and consumed; while the low-frequency operating current is easier to flow from the copper However, it is not easy to be consumed, thus realizing the separation of working current and noise current. Due to the existence of high dielectric constant ceramic materials 202, 206 and 210, the capacitance between the two busbars is a differential mode capacitance, which can reflect the differential mode interference current back to the source; the capacitance between the busbar and the edge nickel layer is a common mode capacitance , can transfer the common mode interference current to the earth. the

FIG. 3 is a connection diagram of the bus-type EMI filter. Among them, the coil ports 301 and 305 are connected to the bus ports 303 and 304 with wires. When the whole structure is regarded as a two-port network, one of the ports is 302 and 306 of the coil, and the other port is the bus bars 307 and 308. The parasitic parameters are ignored. And the approximate equivalent circuit of resistance effect is shown in Fig. 4. the

The various parameters of the bus-type EMI filter can be obtained by the following formula: Assume that the ceramic thickness of the linear capacitor bus integrated module is d, the width is w, the relative permittivity is ε _r , the effective cross-sectional area of the magnetic core is A, etc. The length of the effective magnetic circuit is l, the number of turns of the coil is N, and the relative magnetic permeability is μ _r , then the difference is that the common-mode capacitance is

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; CM</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; CM</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; DM</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; wl</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}$

where ε ₀ is the permittivity of air; the common mode inductance is

${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; CM</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; CM</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}$

where μ ₀ is the vacuum permeability.

A specific example of the present invention has been described in detail above, but it should be understood that the embodiments of the present invention are not limited thereto, and this example is only used to help understand the present invention. Various changes made to the present invention should be included within the scope of the present invention. The patent protection scope of the present invention should be limited by the appended claims. the

Claims (4)

1. common mode inductance strengthens a bus type electromagnetic interface filter for structure, it is characterized in that, comprises linear pattern electric capacity bus integration module (102) and wound core inductor module, wherein:

Described wound core inductor module is made up of U-shaped magnetic core (101), the first coil (103), the second coil (104) and I type magnetic core (105), and described first coil (103), the second coil (104) are around to identical and be enclosed within two magnetic posts of U-shaped magnetic core (101) respectively; Described U-shaped magnetic core (101) and I type magnetic core (105) composition closed magnetic circuit;

A port (301) of described first coil (103), a port (305) of the second coil (104) are connected with two bus ports (303,304) of linear pattern electric capacity bus integration module (102) one end respectively; Two bus ports (307,308) of described linear pattern electric capacity bus integration module (102) other end and another port (302) of the first coil (103), another port (306) of the second coil (104) form the input/output end port of described bus type electromagnetic interface filter;

The inductance of described wound core inductor module is common mode inductance, leakage inductance is differential mode inductance;

Described wound core inductor module is enclosed within described linear pattern electric capacity bus integration module (102).

2. common mode inductance according to claim 1 strengthens the bus type electromagnetic interface filter of structure, it is characterized in that, described linear pattern electric capacity bus integration module (102) comprises 11 layer material structures, be respectively from ground floor to eleventh floor: the first nickel dam (201), first high dielectric constant material layer (202), second nickel dam (203), first layers of copper (204), 3rd nickel dam (205), second high dielectric constant material layer (206), 4th nickel dam (207), second layers of copper (208), 5th nickel dam (209), third high dielectric constant material layer (210), 6th nickel dam (211), total with the second high dielectric constant material layer (206) of layer 6 for symmetry axis is symmetrical,

The bus that described first layers of copper (204), the second layers of copper (208) are ON operation electric current;

Described first nickel dam (201), the first high dielectric constant material layer (202), the second nickel dam (203) form common mode capacitance;

Described 5th nickel dam (209), third high dielectric constant material layer (210), the 6th nickel dam (211) form common mode capacitance;

Described 3rd nickel dam (205), the second high dielectric constant material layer (206), the 4th nickel dam (207) form differential mode capacitor;

Described first nickel dam (201), the 6th nickel dam (211) operationally ground connection.

3. common mode inductance according to claim 2 strengthens the bus type electromagnetic interface filter of structure, it is characterized in that, each high dielectric constant material layer described adopts ceramic material.

4. common mode inductance according to claim 3 strengthens the bus type electromagnetic interface filter of structure, and it is characterized in that, described ceramic material is BaTiO ₃or CaCu ₃ti ₄o ₁₂.