Magnetic field sensor and electrical current sensor therewith

1. Open-loop electrical current sensor for measuring a primary electrical current I p flowing in a primary conductor ( 1 ), including a magnetic circuit ( 3 ) comprising a generally annular shaped core ( 5 ) of soft magnetic material surrounding a central opening ( 7 ) configured to allow a primary conductor to extend therethrough and having an air-gap ( 6 ) formed between end faces ( 27 a , 27 b ) of said core, and a magnetic field sensor positioned in the air-gap, the magnetic field sensor comprising a magnetic field sensing cell ( 10 , 310 ) and a magnetic shield ( 9 , 109 , 209 , 409 ) made of a magnetic material comprising at least two parts ( 12 , 112 , 212 , 412 ) separated by an air-gap ( 20 ) and surrounding the magnetic field sensing cell positioned within a cavity ( 11 ) of the magnetic shield, the magnetic field sensing cell comprising a saturable soft magnetic core ( 17 , 317 ) surrounded by a coil ( 16 ) connected to a circuit for generating and processing the electrical signals of the magnetic field sensing cell in order to provide an output signal that is a function of the primary electrical current.

2. Open-loop electrical current sensor according to claim 1 , wherein the magnetic field sensing cell comprises a flexible circuit ( 14 , 214 ) extending into the magnetic shield through a slot ( 13 , 113 , 213 ) and connected to said coil ( 16 ) of the sensing cell.

3. Open-loop electrical current sensor according to claim 1 , further comprising a circuit board ( 22 ) with conductive tracks thereon, wherein the magnetic field sensor ( 4 , 104 , 204 , 304 , 404 ) is mounted on the circuit board.

4. Open-loop electrical current sensor for measuring a primary electrical current I p flowing in a primary conductor ( 1 ), including a magnetic circuit ( 3 ) comprising a generally annular shaped core ( 5 ) of soft magnetic material surrounding a central opening ( 7 ) configured to allow a primary conductor to extend therethrough and having an air-gap ( 6 ) formed between end faces ( 27 a , 27 b ) of said core, and a magnetic field sensor positioned in the air-gap, the magnetic field sensor comprising a magnetic field sensing cell ( 10 , 310 ) and a magnetic shield ( 9 , 109 , 209 , 409 ) made of a magnetic material comprising at least two parts ( 12 , 112 , 212 , 412 ) separated by an air-gap ( 20 ) and surrounding the magnetic field sensing cell positioned within a cavity ( 11 ) of the magnetic shield, the magnetic field sensing cell comprising a saturable soft magnetic core ( 17 , 317 ) surrounded by a coil ( 16 ) connected to a circuit for generating and processing the electrical signals of the magnetic field sensing cell in order to provide an output signal that is a function of the primary electrical current, further comprising a circuit board ( 22 ) with conductive tracks thereon, wherein the magnetic field sensor ( 4 , 104 , 204 , 304 , 404 ) is mounted on the circuit board and wherein the magnetic field sensor comprises a flexible circuit ( 14 , 214 , 414 ) that is conductively connected to conductive traces on the circuit board that connect the magnetic field sensor to an Application Specific Integrated Circuit (ASIC) ( 23 ) mounted on the circuit board for processing the sensor input and output signals.

5. Electrical current sensor for measuring the electrical current I p flowing in a primary conductor ( 1 ), including a magnetic circuit ( 3 ) comprising a core ( 5 ) of magnetic material surrounding a central opening ( 7 ) through which the primary conductor extends and having an air-gap ( 6 ) formed between end faces ( 27 a , 27 b ) of said core, and a magnetic field sensor mounted in the air-gap, the magnetic field sensor comprising a magnetic field sensing cell ( 10 , 310 ) and a magnetic shield ( 9 , 109 , 209 , 409 ) made of a magnetic material comprising at least two parts ( 12 , 112 , 212 , 412 ) separated by an air-gap ( 20 ) and surrounding the magnetic field sensing cell mounted within a cavity ( 11 ) of the magnetic shield, wherein the magnetic field sensing cell comprises a soft magnetic core ( 17 , 317 ) surrounded by a coil ( 16 ) connected to a circuit for generating and processing the electrical signals of the magnetic field sensing cell in order to provide an output signal that is a function of the magnetic signal to be measured.

6. Electrical current sensor according to claim 5 , wherein the magnetic field sensing cell comprises a flexible circuit ( 14 , 214 ) extending into the magnetic shield through a slot ( 13 , 113 , 213 ) and connected to said coil ( 16 ) of the sensing cell.

7. Electrical current sensor according to claim 5 , further comprising a secondary conductor ( 8 ) wound around the core ( 5 ) of the magnetic circuit for measuring high frequency currents by a transformer effect.

8. Electrical current sensor according to claim 7 , wherein the secondary conductor ( 8 ) is in the form of U-shape wires ( 26 ) positioned over portions of the core ( 5 ) of soft magnetic material and bonded onto conductive tracks of a circuit board ( 22 ).

9. Electrical current sensor according to claim 7 , further comprising a circuit board ( 22 ) with conductive tracks thereon.

10. Electrical current sensor according to claim 9 , wherein the magnetic circuit ( 3 ) is fixed directly on the circuit board.

11. Electrical current sensor according to claim 10 , wherein the magnetic field sensor ( 4 , 104 , 204 , 304 , 404 ) is fixed directly on the circuit board.

12. Electrical current sensor for measuring the electrical current I p flowing in a primary conductor ( 1 ), including a magnetic circuit ( 3 ) comprising a core ( 5 ) of magnetic material surrounding a central opening ( 7 ) through which the primary conductor extends and having an air-gap ( 6 ) formed between end faces ( 27 a , 27 b ) of said core, and a magnetic field sensor mounted in the air-gap, the magnetic field sensor comprising a magnetic field sensing cell ( 10 , 310 ) and a magnetic shield ( 9 , 109 , 209 , 409 ) made of a magnetic material comprising at least two parts ( 12 , 112 , 212 , 412 ) separated by an air-gap ( 20 ) and surrounding the magnetic field sensing cell mounted within a cavity ( 11 ) of the magnetic shield, further comprising a circuit board ( 22 ) with conductive tracks thereon, wherein the-magnetic field sensor comprises a flexible circuit ( 14 , 214 , 414 ) that is conductively connected to conductive traces on the circuit board that connect the magnetic field sensor to an Application Specific Integrated Circuit (ASIC) ( 23 ) mounted on the circuit board for processing the sensor input and output signals.

13. Magnetic field sensor configured to be positioned in an external magnetic field generated by a magnetic field generating system positioned outside of the sensor, comprising a magnetic field sensing cell ( 10 , 310 ) and a magnetic shield ( 9 , 109 , 209 , 409 ) made of a magnetic material comprising at least two parts ( 12 , 112 , 212 , 412 ) separated by an air-gap ( 20 ) and surrounding the magnetic field sensing cell positioned within a cavity ( 11 ) of the magnetic shield, wherein the magnetic field sensing cell comprises a soft magnetic core ( 17 , 317 ) surrounded by a coil ( 16 ) connected to a circuit for generating and processing the electrical signals of the magnetic field sensing cell in order to provide an output signal that is a function of the magnetic signal to be measured.

14. Magnetic field sensor according to claim 13 , wherein the soft magnetic core of the magnetic field sensing cell comprises one or more ribbons made of a soft magnetic material.

15. Magnetic field sensor according to claim 13 , wherein the soft magnetic core of the magnetic field sensing cell comprises fine wires made of a soft magnetic material bundled together.

16. Magnetic field sensor according to claim 13 , wherein the magnetic shield has an essentially axisymmetric shape about a central axis and is arranged in a magnetic field to be measured such that the central axis is substantially parallel to flux lines of the magnetic field.

17. Magnetic field sensor according to claim 13 , wherein the air-gap of the magnetic shield is essentially planar and perpendicular to the magnetic flux lines.

18. Magnetic field sensor according to claim 13 , wherein the magnetic shield is provided with a longitudinal slot ( 13 , 113 , 213 , 413 ) to reduce eddy currents in the magnetic shield.

19. Magnetic field sensor according to claim 13 , wherein the magnetic shield is at least partially stamped and formed from sheet metal.

20. Magnetic field sensor configured to be positioned in an external magnetic field generated by a magnetic field generating system positioned outside of the sensor, comprising a magnetic field sensing cell ( 10 , 310 ) and a magnetic shield ( 9 , 109 , 209 , 409 ) made of a magnetic material comprising at least two parts ( 12 , 112 , 212 , 412 ) separated by an air-gap ( 20 ) and surrounding the magnetic field sensing cell positioned within a cavity ( 11 ) of the magnetic shield, further comprising a flexible circuit ( 14 , 214 ) extending into the magnetic shield through a slot ( 13 , 113 , 213 ) and connected to a coil ( 16 ) of the sensing cell.