CN-121983417-A - Electromagnetic interference filter based on flexible multilayer strip

Abstract

The invention discloses an electromagnetic interference filter based on a flexible multilayer strip, which comprises an EE type magnetic core, a first winding, a second winding, a third winding and a fourth winding, wherein the first winding is wound on a first side column, the fourth winding is wound on a second side column, the first winding and the fourth winding are both formed by the flexible multilayer strip, the flexible multilayer strip comprises a first copper foil layer, a first dielectric layer, a second copper foil layer, a second dielectric layer, a third copper foil layer, a third dielectric layer and a fourth copper foil layer which are sequentially overlapped, the first copper foil layer is electrically connected with the third copper foil layer to form an L-line common mode inductance winding, the second copper foil layer is electrically connected with the fourth copper foil layer to form an N-line common mode inductance winding, a ground layer is arranged between the second copper foil layer and the third copper foil layer, and the second winding and the third winding are both formed by a single copper foil layer and are wound on a middle column of the EE type magnetic core together. Compared with the prior art, the invention can effectively inhibit high-frequency EMI noise.

Inventors

• LIU YITAO
• ZHOU YISHUN
• LIU XINGYU

Assignees

• 深圳大学

Dates

Publication Date

20260505

Application Date

20260304

Claims (9)

1. 1. An electromagnetic interference filter based on flexible multilayer strips, characterized by comprising an EE-type magnetic core, a first winding, a second winding, a third winding and a fourth winding, wherein: The EE type magnetic core comprises a first side column, a second side column and a middle column positioned between the first side column and the second side column, and an air gap is formed in the middle column; the first winding is wound on the first side column, the fourth winding is wound on the second side column, and the first winding and the fourth winding are both composed of flexible multi-layer strips, wherein each flexible multi-layer strip comprises a first copper foil layer, a first dielectric layer, a second copper foil layer, a second dielectric layer, a third copper foil layer, a third dielectric layer and a fourth copper foil layer which are sequentially stacked; The first copper foil layer is electrically connected with the third copper foil layer to form an L-line common mode inductance winding; The second copper foil layer is electrically connected with the fourth copper foil layer to form an N-wire common mode inductance winding; A grounding layer is arranged between the second copper foil layer and the third copper foil layer; The second winding and the third winding are both composed of a single copper foil layer and are wound on the center post of the EE type magnetic core together.
2. 2. The flexible multilayer strip-based electromagnetic interference filter of claim 1, wherein the first winding and the fourth winding are wound on the first leg and the second leg in a bifilar parallel winding manner, and the number of winding turns of the first winding is equal to the number of winding turns of the fourth winding.
3. 3. The flexible multilayer strip-based electromagnetic interference filter of claim 1, wherein the second winding and the third winding are each wound on the center post in a single wire wound configuration, and the number of turns of the second winding is equal to the number of turns of the third winding.
4. 4. The flexible multilayer tape based electromagnetic interference filter of claim 1, wherein the first winding, the second winding, the third winding and the fourth winding are sequentially arranged from right to left along a yoke of the EE-type magnetic core.
5. 5. The flexible multilayer tape based electromagnetic interference filter of claim 1, wherein the equivalent magnetic resistance of the electromagnetic interference filter is calculated by a first formula: ; Wherein, the Is the equivalent magnetic resistance of the side column, Is the equivalent magnetic resistance of the EE type magnetic core yoke, Is the equivalent magnetic resistance of the center pillar, Is the equivalent magnetic resistance of the air gap of the center pillar, 、 、 And For the cross-sectional area of the corresponding magnetic column, For the magnetic path length of the side posts, For the magnetic path length of the yoke, For the magnetic path length of the center pillar, For the magnetic path length of the air gap, Is the magnetic permeability of the air, and is a magnetic permeability of the air, Is the relative permeability of the magnetic core.
6. 6. The flexible multilayer tape based electromagnetic interference filter of claim 5, wherein the common mode inductance of the first winding is calculated by a second formula: ; Wherein, the For the common-mode inductance of the first winding, Is the coupling coefficient of the side column winding, Is the number of winding turns of the first winding, ; Calculating the common mode inductance of the fourth winding through a third formula, wherein the third formula is as follows: ; Wherein, the For the common-mode inductance of the fourth winding, Is the coupling coefficient of the side column winding, The number of winding turns for the fourth winding, 。
7. 7. The flexible multilayer tape based electromagnetic interference filter of claim 5, wherein the differential mode inductance of the second winding is calculated by a fourth formula: ; Wherein, the For the common-mode inductance of the second winding, The number of winding turns for the fourth winding, , ; Calculating the differential mode inductance of the third winding by a fifth formula: ; Wherein, the For the common-mode inductance of the third winding, Is the number of winding turns of the third winding, , 。
8. 8. The flexible multilayer tape based electromagnetic interference filter of claim 5, wherein the differential mode capacitance value of the electromagnetic interference filter is calculated by a sixth formula: ; Wherein, the Is the value of the differential-mode capacitance, The number of layers being a flexible multi-layer tape, As the relative permittivity of the dielectric layer, For the dielectric constant in vacuum, For the length of the conductor layer, For the width of the conductor layer, For the thickness of the dielectric layer, Is the thickness of the insulating layer.
9. 9. The flexible multilayer tape based electromagnetic interference filter of claim 1, wherein the common mode capacitance value of the electromagnetic interference filter is calculated by a seventh formula: ; Wherein, the Is the value of the common-mode capacitance, As the relative permittivity of the dielectric layer, For the dielectric constant in vacuum, For the length of the embedded formation, For the width of the conductor layer, Is the thickness of the dielectric layer.

Description

Electromagnetic interference filter based on flexible multilayer strip Technical Field The invention belongs to the technical field of filters, and provides an electromagnetic interference filter based on a flexible multilayer strip. Background With the rapid development of power electronics technology, grid-connected inverter systems are continuously evolving towards high frequency, light weight and high power density. In this trend, the increasing switching frequency of the system helps to miniaturize and increase efficiency of the system, but also results in a significant increase in conducted electromagnetic interference (Electromagnetic Interference, EMI) noise. However, the conventional filter mainly suppresses low-frequency noise (such as power frequency harmonic), and it is difficult to effectively cope with high-frequency EMI noise. The prior art constructs a four-layer composite structure by using Flexible multi-layer tapes (FMLF) and UU type magnetic cores, integrating Common Mode (CM) inductors and CM capacitors to improve the suppression capability of high frequency noise. However, the UU-type magnetic core only has two independent magnetic legs, lacks the middle magnetic pillar, causes that the magnetic circuit closure is poor, the magnetic resistance is great, influences magnetic coupling efficiency to reduce the inductance value stability of CM inductance, and the magnetic core window structure is loose, causes FMLF winding to be difficult to closely laminate the magnetic leg, causes window space waste. Disclosure of Invention The invention mainly aims to provide an electromagnetic interference filter based on a flexible multilayer strip, and aims to solve the problem that in the prior art, a four-layer composite structure is built by using FMLF and UU type magnetic cores, and CM inductance and CM capacitance are integrated to improve the high-frequency noise suppression capability. However, the UU type magnetic core only possesses two independent magnetic legs, lacks the middle magnetic pillar, leads to magnetic circuit closure poor, the magnetic resistance is great, influence magnetic coupling efficiency to reduce the inductance value stability of CM inductance, and the magnetic core window structure is loose, leads to FMLF winding to be difficult to closely laminate the magnetic leg, causes the extravagant problem of window space. In order to achieve the above objective, the invention provides an electromagnetic interference filter based on a flexible multilayer strip, which comprises an EE type magnetic core, a first winding, a second winding, a third winding and a fourth winding, wherein the EE type magnetic core comprises a first side column, a second side column and a middle column positioned between the first side column and the second side column, an air gap is formed on the middle column, the first winding is wound on the first side column, the fourth winding is wound on the second side column, the first winding and the fourth winding are all composed of flexible multilayer strips, the flexible multilayer strip comprises a first copper foil layer, a first dielectric layer, a second copper foil layer, a second dielectric layer, a third copper foil layer, a third dielectric layer and a fourth copper foil layer which are sequentially stacked, the first copper foil layer is electrically connected with the third copper foil layer to form an L-wire common mode inductance winding, the second copper foil layer is electrically connected with the fourth copper foil layer to form an N-wire common mode inductance winding, a grounding layer is arranged between the second copper foil layer and the third copper foil layer, and the second copper foil layer and the third copper foil layer are all composed of a single copper foil layer and are wound on the EE type magnetic core. Optionally, the first winding and the fourth winding are wound on the first side column and the second side column in a double-wire parallel winding mode, and the number of turns of the first winding is equal to that of the fourth winding. Optionally, the second winding and the third winding are wound on the center post by adopting a single-wire winding structure, and the number of turns of the second winding is equal to the number of turns of the third winding. Optionally, the first winding, the second winding, the third winding and the fourth winding are sequentially arranged along the yoke of the EE-type magnetic core from right to left. Optionally, the equivalent magnetic resistance of the electromagnetic interference filter is calculated by a first formula: Wherein, the Is the equivalent magnetic resistance of the side column,Is the equivalent magnetic resistance of the EE type magnetic core yoke,Is the equivalent magnetic resistance of the center pillar,Is the equivalent magnetic resistance of the air gap of the center pillar,、、AndFor the cross-sectional area of the corresponding magnetic column,For the magnetic path