METHOD AND SENSOR FOR SENSING CURRENT IN A CONDUCTOR

• US 20140253108A1
• Filed: 03/08/2013
• Published: 09/11/2014
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Clements, Neal D., Wieland, Andrew D., Singh, Brij N, Fisk, Aron
• Granted Patent: US 9,410,990 B2
• Time in Patent Office: Days
• US Class Current: 324/227
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: G01R 15/20 using galvano-magnetic devices, e.g. Hall-effect devices , i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
• CPC Class Codes: G01R 19/0007 Frequency selective voltage or current level measuring measuring frequency G01R23/00; testing attenuation in line transmission systems H04B3/48; monitoring testing in transmission systems H04B17/00
• CPC Class Codes: G01R 31/42 AC power supplies

Abstract

A sensor comprises an inductor for sensing an alternating current signal component of an observed signal. The inductor comprises a substrate, conductive traces associated with different layers of the substrate, and one or more conductive vias for interconnecting the plurality of conductive traces. A magnetic field sensor senses a direct current signal component of the observed signal. A first filtering circuit has a high-pass filter response. The first filtering circuit is coupled to the inductor to provide a filtered alternating current signal component. A second filtering circuit has a low-pass filter response. The second filtering circuit coupled to the magnetic field sensor to provide a filtered direct current signal component. A sensor fusion circuit determines an aggregate sensed current based on the filtered alternating current signal component and the filtered direct current signal component.

Claims

1. A current sensor comprising:

an inductor for sensing an alternating current signal component of an observed signal, the inductor comprising a multi-layered substrate, a plurality of conductive traces associated with different layers of the substrate, and one or more conductive vias for interconnecting the plurality of conductive traces;

a magnetic field sensor for sensing a direct current signal component of the observed signal;

a first filtering circuit having a high-pass filter response, the first filtering circuit coupled to the inductor to provide a filtered alternating current signal component;

a second filtering circuit having a low-pass filter response, the second filtering circuit coupled to the magnetic field sensor to provide a filtered direct current signal component; and

a sensor fusion circuit for accepting the filtered alternating current signal component and the filtered direct current signal component and for determining an aggregate sensed current.

2. The current sensor according to claim 1 further comprising:

a current change detector for determining a change in current versus time for the alternating signal component.

3. The current sensor according to claim 1 wherein the inductor and the magnetic field sensor are arranged to be proximate or near a conductor that connects an inverter output of an inverter to an electric motor.

4. The current sensor according to claim 3 wherein the conductor comprises a bus bar or one or more wire bonds associated with a power semiconductor within an inverter.

5. The current sensor according to claim 3 further comprising:

a temperature sensor for estimating a temperature of the conductor.

6. The current sensor according to claim 1 wherein the sensor fusion circuit is adapted to scale a first gain of the filtered alternating signal component and a second gain of the filtered direct current signal component to obtain a conversion factor between actual current of the observed signal flowing through a conductor and the aggregate sensed current.

7. The current sensor according to claim 1 wherein the substrate comprises a circuit board and wherein the conductive vias comprise buried vias.

8. The current sensor according to claim 1 wherein the conductive traces are radially extending with respect to a central axis, and wherein the conductive traces are arranged in the different layers that are spaced apart from each other by intervening dielectric portions of the substrate.

9. The current sensor according to claim 8 wherein the conductive traces form an inductor with at least two taps or terminals, where the conductive traces of each layer of the layers are confined to a generally annular region on the substrate.

10. The current sensor according to claim 1 wherein the magnetic field sensor comprises a programmable or pre-programmed Hall Effect sensor.

11. The current sensor according to claim 10 wherein the magnetic field sensor is associated with a ferrite structure to attenuate stray electromagnetic fields that might otherwise result in distortions in the measurement of the direct current component.

12. The current sensor according to claim 11 wherein the ferrite structure comprises a toroidal core with an air gap and wherein the magnetic field sensor or its probe is mounted in the air gap.

13. The current sensor according to claim 11 wherein the ferrite structure comprises a ferrite members that are placed on opposite sides of the magnetic field sensor or its probe, where the ferrite members are aligned about a common axis.

14. The current sensor according to claim 1 wherein the first filtering circuit, the second filtering circuit and the sensor fusion circuit are formed by mounting electronic components on one or more sides of the substrate in a region outward from an annular region or annular volume of the inductor.

15. The current sensor according to claim 1 wherein the first filtering circuit, the second filtering circuit and the sensor fusion circuit each comprise one or more operational amplifiers and resistors that are interconnected via secondary circuit traces on the substrate.

16. A method for sensing current, the method comprising:

sensing, via an inductor, an alternating current signal component of an observed signal, the inductor comprising a substrate, a plurality of conductive traces associated with different layers of the substrate, and one or more conductive vias for interconnecting the plurality of conductive traces;

sensing a direct current signal component of the observed signal;

filtering the alternate current signal component with a high-pass filter response to provide a filtered alternating current signal component;

filtering the direct current signal component with a low pass filter response to provide a filtered direct current signal component; and

determining an aggregate sensed current by combining the filtered alternating current signal component and the filtered direct current signal component.

17. The method according to claim 16 further comprising:

determining a change in current versus time for the alternating signal component.

18. The method according to claim 16 further comprising:

estimating a temperature of a conductor for carrying the observed signal.

19. The method according to claim 16 wherein arranging the inductor to be proximate or near a conductor that connects an inverter output of an inverter to an electric motor.

20. The method according to claim 19 further comprising:

scaling a first gain of the filtered alternating signal component and a second gain of the filtered direct current signal component to obtain a conversion factor between actual current of the observed signal flowing through the conductor and the aggregate sensed current.

21. The method according to claim 16 further comprising:

arranging the conductive traces in the different layers that are spaced apart from each other by intervening dielectric portions of a substrate wherein the conductive traces are radially extending with respect to a central axis and are limited to occupy a generally annular area or volume of the substrate.

22. The method according to claim 16 further comprising:

mounting electronic components on one or more sides of the substrate in a region outward from an annular region or annular volume of the inductor to form at least a first filtering circuit, a second filtering circuit and a sensor fusion circuit on the substrate.