Magnetic field sensor and electrical current sensor therewith

• US 20060226826A1
• Filed: 02/18/2004
• Published: 10/12/2006
• Est. Priority Date: 02/21/2003
• Status: Active Grant

• Current Assignee: Liaisons Electroniques-Mecaniques LEM SA
• Original Assignee: Liaisons Electroniques-Mecaniques LEM SA
• Inventors: Teppan, Wolfram
• Granted Patent: US 7,622,909 B2
• Time in Patent Office: Days
• US Class Current: 324/117.H
• CPC Class Codes: G01R 15/185 with compensation or feedback windings or interacting coils, e.g. 0-flux sensors using galvano-magnetic field sensors G01R15/20; conversion of DC into AC using transductors G01R19/20
• CPC Class Codes: G01R 15/202 using Hall-effect devices Hall elements in arrangements for measuring electrical power G01R21/08
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used
• CPC Class Codes: G01R 33/04 using the flux-gate principle

Abstract

A magnetic field sensor comprises a magnetic field sensing cell and a magnetic shield comprising at least two parts separated by an air-gap and surrounding the magnetic field sensing cell positioned in a cavity of the magnetic shield.

Claims

1-17. -17. (canceled)

18. Magnetic field sensor comprising a magnetic field sensing cell (10, 310) and a magnetic shield (9, 109, 209, 409), comprising at least two parts (12, 112, 212, 412) separated by an air-gap (20) and surrounding the magnetic field sensing cell positioned in a cavity (11) of the magnetic shield.

19. Magnetic field sensor according to claim 18, 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.

20. Magnetic field sensor according to claim 18, 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.

21. Magnetic field sensor according to claim 19, wherein the soft magnetic core of the magnetic field sensing cell comprises one or more ribbons made of a soft magnetic material

22. Magnetic field sensor according to claim 19, wherein the soft magnetic core of the magnetic field sensing cell comprises fine wires made of a soft magnetic material bundled together.

23. Magnetic field sensor according to claim 18, 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.

24. Magnetic field sensor according to claim 18, wherein the air-gap of the magnetic shield is essentially planar and perpendicular to the magnetic flux lines.

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

26. Magnetic field sensor according to claim 18, wherein the magnetic shield is at least partially stamped and formed from sheet metal.

27. Electrical current sensor for measuring the electrical current I_p flowing in a primary conductor (1), comprising a magnetic circuit (3) having an air-gap (6) and a magnetic field sensor according to claim 18 positioned in the air-gap.

28. Electrical current sensor according to claim 27, wherein the magnetic circuit comprises a core (5) of soft magnetic material surrounding the primary conductor, end faces (27a, 27b) of the core having extensions (28a, 28b) that reduce the width of the air-gap along an outer periphery of the magnetic core.

29. Electrical current sensor according to claim 27, further comprising a secondary conductor (8) wound around the magnetic core for measuring high frequency currents by the transformer effect.

30. Electrical current sensor according to claim 27, further comprising a circuit board (22) with conductive tracks thereon.

31. Electrical current sensor according to claim 30, wherein the magnetic circuit (3) is fixed directly on the circuit board.

32. Electrical current sensor according to claim 31, wherein the magnetic field sensor (4, 104, 204, 304, 404) is fixed directly on the circuit board.

33. Electrical current sensor according to claim 32, wherein the flexible circuit (14, 214, 414) of the magnetic field sensor is conductively connected to conductive traces on the circuit board that connect the magnetic field sensor to an ASIC (23) mounted on the circuit board for processing the sensor input and output signals.

34. Electrical current sensor according to claim 33, wherein the conductors of a secondary winding (8) in the form of U-shape wires (26) are positioned over portions of the magnetic core (5) and bonded onto conductive traces of the circuit board (22).