# US 12,470,191 B2 · Electromagnetic filter for operating in common and differential mode

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- Number: US 12,470,191 B2
- Document ID: US12470191B2
- Status: Granted
- Kind: B2
- Application number: 18/545,116
- Filed: 2023-12-19
- Published: 2024-06-27
- Granted: 2025-11-11
- Earliest claimed: 2022-12-21
- Assignees: Premo, S.L.
- Applicants: Premo, S.L.
- Inventors: Juan Miguel Cuesta Cano; Paula Pérez Camero; Antonio Rojas Cuevas; Claudio Cañete Cabeza; Francisco Ezequiel Navarro Pérez
- Web page: https://patentgrep.com/patent/US12470191B2

## CPC

- H01F 17/062: {Toroidal core with turns of coil around it}
- H03H 7/0115: {comprising only inductors and capacitors (H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence)}
- H01F 27/022: {Encapsulation}
- H01F 27/08: Cooling (heat-transfer elements F28F); Ventilating (structural details of casings H01F27/02)
- H01F 27/24: Magnetic cores
- H01F 27/2895: {Windings disposed upon ring cores}
- H01F 27/306: {Fastening or mounting coils or windings on core, casing or other support}
- H01F 27/38: Auxiliary core members; Auxiliary coils or windings
- H01F 27/40: Structural association with built-in electric component, e.g. fuse
- H01F 38/48: {Common mode inductor for reducing or eliminating common mode noise on parallel lines}
- H01F 27/22: Cooling by heat conduction through solid or powdered fillings
- H01F 2017/048: {with encapsulating core, e.g. made of resin and magnetic powder}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

An electromagnetic filter for operating in common and differential mode having a toroidal-like magnetic core; first and second separated coils wound around the magnetic core, the first and second coils and the magnetic core configured to provide a common mode filter. The filter also has a third coil that surrounds the magnetic core and the first and second coils and arranged around a Z axis that is coaxial with an inner hollow part of the magnetic core, the third coil being configured to provide a filter operating in differential mode. Two sheets are also arranged between opposite external faces of a capacitor to thermally isolate the capacitor from the coils, the capacitor and sheets being arranged inside the inner hollow part. A layer of a thermal conductive magnetic compound encloses all the elements to increase leakage inductance and to enclose a magnetic field generated by the third coil.

## Claims

### Claim 1

An electromagnetic filter configured to operate in common and differential mode, comprising:
a toroidal-like magnetic core;
first and second separated coils wound around the toroidal-like magnetic core and arranged around a Z axis that is coaxial with an inner hollow part of the toroidal-like magnetic core, the first and second separated coils and the toroidal-like magnetic core being configured to provide a common mode filter, the first and second separated coils are arranged in opposition to each other and around two major separated segments of the toroidal-like magnetic core;
a third coil that is arranged to surround the toroidal-like magnetic core, the third coil being configured to provide a filter operating in differential mode;
at least one capacitor;
two sheets arranged between opposite external faces of the capacitor to thermally isolate the capacitor from the first and second separated coils;
the capacitor and the two sheets being arranged inside the inner hollow part of the toroidal-like magnetic core; and
a layer of a thermal conductive magnetic compound configured to enclose the toroidal-like magnetic core, the first, second and third coils, the capacitor and the two sheets, such that leakage inductance is increased, a magnetic field generated by the third coil is enclosed, and a good thermal link to a cooling plate is provided.

### Claim 2 (depends on 1)

The electromagnetic filter according to claim 1, wherein the toroidal-like magnetic core is oval and elongated.

### Claim 3 (depends on 1)

The electromagnetic filter according to claim 1, wherein the toroidal-like magnetic core is elliptical.

### Claim 4 (depends on 1)

The electromagnetic filter according to claim 1, wherein the third coil is arranged perpendicularly with respect to the first and second separated coils.

### Claim 5 (depends on 1)

The electromagnetic filter according to claim 1, wherein the third coil is decoupled with regard to the first and second separated coils.

### Claim 6 (depends on 1)

The electromagnetic filter according to claim 1, wherein the two sheets are made of a polystyrene material.

### Claim 7 (depends on 1)

The electromagnetic filter according to claim 1, wherein the toroidal-like magnetic core is a nanocrystalline core.