Non-contact type current sensor and associated methods

Patent metadata

Field	Value
Publication number	US-9927509-B2
Application number	US-201514930252-A
Country	US
Kind code	B2
Filing date	Nov 2, 2015
Priority date	Nov 2, 2015
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A current measurement device is provided for use with a measurement target having a conductive path. The current measurement device includes a non-contact current sensor to be positioned adjacent the conductive path of the measurement target. A calibration current superimposing unit, including a first electrode and a second electrode to be positioned in contact with the conductive path of the measurement target, is configured to output a calibration current to flow through the conductive path between the first electrode and the second electrode. A controller, coupled to the non-contact current sensor and the calibration current superimposing unit, is configured to control the output of the calibration current from the calibration current superimposing unit, and is configured to sample a signal from the non-contact current sensor positioned adjacent the conductive path of the measurement target.

First claim

The invention claimed is:

1. A current measurement device for use with a measurement target having a conductive path, the current measurement device comprising:
a non-contact current sensor to be positioned adjacent the conductive path of the measurement target;
a calibration current superimposing unit, including a first electrode and a second electrode to be positioned in contact with the conductive path of the measurement target, and configured to output a calibration current to flow through the conductive path between the first electrode and the second electrode; and
a controller, coupled to the non-contact current sensor and the calibration current superimposing unit, and configured to control the output of the calibration current from the calibration current superimposing unit, and configured to sample a signal from the non-contact current sensor positioned adjacent the conductive path of the measurement target.

2. The current measurement device according to claim 1 , wherein the calibration current superimposing unit comprises:
a floating current source comprising a first output terminal and a second output terminal;
an amplifier connected to the first output terminal of the floating current source; and
a floating ground terminal connected to the second output terminal of the floating current source.

3. The current measurement device according to claim 2 , wherein the floating current source comprises:
a signal source;
a signal isolator configured to output an output of the signal source to the first output terminal and the second output terminal; and
a ground terminal connected to an output of the signal source, and insulated from the floating ground terminal.

4. The current measurement device according to claim 1 , wherein the calibration current superimposing unit is configured to output the calibration current having a signal component of a first amplitude at a first frequency.

5. The current measurement device according to claim 1 , wherein the calibration current superimposing unit is configured to output the calibration current as a pulse waveform.

6. The current measurement device according to claim 1 , wherein the calibration current superimposing unit is configured to output the calibration current as an M-sequence waveform.

7. The current measurement device according to claim 1 , further comprising a first positioner and a second positioner, configured to position the first electrode and the second electrode, respectively, to be in contact with a conductive pattern of the measurement target.

8. The current measurement device according to claim 7 , further comprising a third positioner for positioning the non-contact current sensor adjacent the conductive path of the measurement target.

9. A method of measuring a current flowing through a measurement target with a current measurement device that includes a non-contact current sensor and a calibration current superimposing unit comprising a first electrode and a second electrode, the method comprising:
positioning the non-contact current sensor adjacent a conductive pattern of the measurement target;
positioning the first electrode and the second electrode in contact with the conductive pattern of the measurement target;
causing a calibration current to flow through the measurement target between the first electrode and the second electrode from the calibration current superimposing unit; and
measuring a signal from the non-contact current sensor adjacent the conductive pattern of the measurement target.

10. The method according to claim 9 , wherein the calibration current includes a predetermined characteristic; and further comprising
extracting a component corresponding to the predetermined characteristic of the calibration current by analyzing the measured signal;
acquiring a transfer function of the measurement target from the extracted component; and
acquiring a corrected current value through use of the transfer function.

11. The method according to claim 10 , further comprising stopping flow of the calibration current after measuring; and wherein acquiring the corrected current value comprises measuring a subsequent signal from the non-contact current sensor and acquiring the corrected current value by applying the transfer function to the subsequent measured signal.

12. The method according to claim 10 , wherein acquiring the corrected current value comprises acquiring the corrected current value by applying the transfer function to a value of the measured signal.

13. The method according to claim 10 , wherein the predetermined characteristic of the calibration current comprises a signal component of a first amplitude at a first frequency.

14. The method according to claim 10 , wherein the predetermined characteristic of the calibration current comprises a plurality of predetermined frequency components; and wherein acquiring the transfer function comprises avoiding using one of the plurality of predetermined frequency components to acquire the transfer function based upon a deviation of an amplitude extracted for the one of the plurality of predetermined frequency components of the calibration current.

15. The method according to claim 9 , wherein positioning the first electrode and the second electrode comprises positioning the first electrode and the second electrode through use of a first positioner and a second positioner, respectively.

16. The method according to claim 15 , wherein positioning the non-contact current sensor comprises positioning the non-contact current sensor, adjacent the conductive pattern of the measurement target, through use of a third positioner.

17. A method of measuring a current flowing through a measurement target with a current measurement device that includes a non-contact current sensor, a calibration current superimposing unit comprising a first electrode and a second electrode, the method comprising:
positioning the non-contact current sensor adjacent a conductive pattern of the measurement target;
positioning the first electrode and the second electrode in contact with the conductive pattern of the measurement target;
causing a calibration current having a predetermined characteristic to flow through the measurement target between the first electrode and the second electrode from the calibration current superimposing unit;
acquiring a first waveform by measuring a voltage signal from the non-contact current sensor adjacent the conductive pattern of the measurement target;
stopping flow of the calibration current;
acquiring a second waveform by measuring a second voltage signal from the non-contact current sensor;
extracting a component corresponding to the predetermined characteristic of the calibration current by analyzing the first waveform and the second waveform;
acquiring a transfer function of the measurement target from the extracted component; and
acquiring a corrected current value through use of the transfer function.

18. The method according to claim 17 , wherein extracting the component corresponding to the predetermined characteristic comprises subjecting each of the first waveform and the second waveform to a frequency analysis to calculate a difference in amplitude at a predetermined frequency.

19. The method according to claim 17 , wherein acquiring the corrected current value comprises applying the transfer function to a value of the second waveform to acquire the corrected current value.

20. The method according to claim 17 , wherein positioning the first electr

Assignees

• Keysight Technologies Inc

Inventors

• Miyake Yasuhiro

Classifications

• G01R19/0092

  Measuring current only · CPC title

• G01R1/02

  General constructional details · CPC title

• G01R35/005 Primary

  Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references (G01R33/0035, G01R35/002 take precedence) · CPC title

• G01R15/14

  Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks · CPC title