Current sensor

• US 10,247,758 B2
• Filed: 08/08/2016
• Issued: 04/02/2019
• Est. Priority Date: 08/08/2016
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Milano, Shaun D., Cisar, Peter, Kranz, Stefan, Schurt, Stephan
• Primary Examiner(s): Aurora, Reena
• Application Number:
  US15/231,133
• Publication Number:
  US 20180038897A1
• Time in Patent Office: 967 Days
• Field of Search: 324127
• CPC Class Codes: G01R 15/183 using transformers with a magnetic core
• 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 15/205 using magneto-resistance devices, e.g. field plates

Abstract

A current sensor includes a ferromagnetic core having a substantially central opening for receiving a current conductor and at least two gaps portions, each of the gap portions having an associated gap spacing. A detector of the current sensor includes at least one first sensing element disposed in a first one of the gap portions and configured to generate a respective first magnetic field signal in response to a first magnetic field generated in the first gap portion in response to a current through the current conductor. The detector also includes at least one second sensing element disposed in a second one of the gap portions and configured to generate a respective second magnetic field signal in response to a second magnetic field generated in the second gap portion in response to the current through the conductor. A method of sensing a current through a current conductor is also provided.

Claims

1. A current sensor, comprising:

a ferromagnetic core having a substantially central opening for receiving a current conductor and at least two gaps portions, each of the gap portions having an associated gap spacing; and

a detector comprising at least one first magnetic field sensing element disposed in a first one of the gap portions and configured to generate a respective first magnetic field signal in response to a first magnetic field generated in the first gap portion in response to a current through the current conductor, and at least one second magnetic field sensing element disposed in a second one of the gap portions and configured to generate a respective second magnetic field signal in response to a second magnetic field generated in the second gap portion in response to the current through the conductor, wherein the first magnetic field has a magnitude greater than the second magnetic field, wherein the detector further comprises a first circuit portion responsive to the first magnetic field signal and a second, substantially identical circuit portion responsive to the second magnetic field signal, and wherein a sensitivity of the first circuit portion is calibrated based on the spacing of the first gap portion and a sensitivity of the second circuit portion is calibrated based on the spacing of the second gap portion to be lower than the sensitivity of the first circuit portion.

2. The current sensor of claim 1, wherein the at least one first magnetic field sensing element is configured to sense a first current level range through the current conductor and wherein the at least one second magnetic field sensing element is configured to sense a second, higher current level range through the current conductor.

3. The current sensor of claim 1, wherein a spacing between the at least one first magnetic field sensing element and the at least one second magnetic field sensing element is based, at least in part, on a spacing between the first and second gap portions.

4. The magnetic field sensor of claim 1, wherein a lateral cross-section of a gap comprising the gap portions comprises a step shape or a ramp shape.

5. The current sensor of claim 1, wherein the detector further comprises circuitry responsive to the first magnetic field signal and to the second magnetic field signal to provide an output signal of the current sensor indicative of the current through the current conductor.

6. The current sensor of claim 1, wherein the at least one first magnetic field sensing element and the at least one second magnetic field sensing element comprise one or more Hall effect elements.

7. The current sensor of claim 1, wherein the at least one first magnetic field sensing element and the at least one second magnetic field sensing element comprise one or more of an anisotropic magnetoresistance (AMR) element, a giant magnetoresistance (GMR) element, a magnetic tunnel junction (MTJ) element and a tunneling magnetoresistance (TMR) element.

8. The current sensor of claim 1, wherein one of the at least one first magnetic field sensing element and the at least one second magnetic field sensing element comprises one or more Hall effect elements, and wherein the other one of the at least one first magnetic field sensing element and the at least one second magnetic field sensing element comprises one or more magnetoresistance elements.

9. The current sensor of claim 1, wherein the at least one first magnetic field sensing element and the at least one second magnetic field sensing element are supported by a single die.

10. The current sensor of claim 1, wherein the at least one first magnetic field sensing element is supported by a first die and wherein the at least one second magnetic field sensing element is supported by a second, different die.

11. The current sensor of claim 10, wherein the first die and the second die are provided in a single integrated circuit package.

12. The current sensor of claim 10, wherein the first die and the second die are provided in separate integrated circuit packages.

13. The current sensor of claim 1, wherein the detector further comprises at least one third magnetic field sensing element disposed between the at least one first magnetic field sensing element and the at least one second magnetic field sensing element and configured to generate a third magnetic field signal, and wherein the detector further comprises a first circuit portion responsive to the first and third magnetic field signals to generate a first differential magnetic field signal, and a second circuit portion responsive to the second and third magnetic field signals to generate a second differential magnetic field signal.

14. A method of sensing a current through a current conductor disposed through a substantially central opening of a ferromagnetic core, the method comprising:

placing a first magnetic field sensing element in a first gap portion of the ferromagnetic core having a first gap spacing, the first magnetic field sensing element generating a first magnetic field signal in response to a first magnetic field in the first gap portion;

placing a second magnetic field sensing element in a second gap portion of the ferromagnetic core having a second gap spacing, larger than the first gap spacing, the second magnetic field sensing element generating a second magnetic field signal in response to a second magnetic field in the second gap portion;

generating a current sensor output signal with a first circuit portion in response to the first magnetic field signal when the current through the current conductor is within a first current level range; and

generating the current sensor output signal with a second circuit portion in response to the second magnetic field signal when the current through the current conductor is within a second, higher current level range, wherein the second circuit portion is substantially identical to the first circuit portion and wherein a sensitivity of the first circuit portion is calibrated based on the spacing of the first gap portion and a sensitivity of the second circuit portion is calibrated based on the spacing of the second gap portion to be lower than the sensitivity of the first circuit portion.

15. The method of claim 14, further comprising providing a sensitivity of the first circuit portion to be greater than a sensitivity of the second circuit portion.

16. The method of claim 14, further comprising providing the first magnetic field sensing element on a first die and providing the second magnetic field sensing element on a second, different die.

17. The method of claim 16, further comprising providing the first and second die in a single integrated circuit package.

18. The method of claim 16, further comprising providing the first and second die in separate integrated circuit packages.

19. A current sensor, comprising:

a ferromagnetic core having a substantially central opening for receiving a current conductor and at least two gaps portions, each of the gap portions having an associated gap spacing; and

a detector comprising at least one first magnetic field sensing element disposed in a first one of the gap portions and configured to generate a respective first magnetic field signal in response to a first magnetic field generated in the first gap portion in response to a current through the current conductor, and at least one second magnetic field sensing element disposed in a second one of the gap portions and configured to generate a respective second magnetic field signal in response to a second magnetic field generated in the second gap portion in response to the current through the conductor, wherein the first magnetic field has a magnitude greater than the second magnetic field, wherein the detector further comprises at least one third magnetic field sensing element disposed between the at least one first magnetic field sensing element and the at least one second magnetic field sensing element and configured to generate a third magnetic field signal, and wherein the detector further comprises a first circuit portion responsive to the first and third magnetic field signals to generate a first differential magnetic field signal, and a second circuit portion responsive to the second and third magnetic field signals to generate a second differential magnetic field signal.

20. A current sensor, comprising:

a ferromagnetic core having a substantially central opening for receiving a current conductor and at least two gaps portions, each of the gap portions having an associated gap spacing; and

a detector comprising at least one first magnetic field sensing element disposed in a first one of the gap portions and configured to generate a respective first magnetic field signal in response to a first magnetic field generated in the first gap portion in response to a current through the current conductor, and at least one second magnetic field sensing element disposed in a second one of the gap portions and configured to generate a respective second magnetic field signal in response to a second magnetic field generated in the second gap portion in response to the current through the conductor, wherein the first magnetic field has a magnitude greater than the second magnetic field, wherein a lateral cross-section of a gap comprising the gap portions comprises a ramp shape.