Vital current sensor

• US 8,566,050 B2
• Filed: 12/15/2010
• Issued: 10/22/2013
• Est. Priority Date: 12/15/2009
• Status: Active Grant

• Current Assignee: Siemens Mobility, Inc. (Siemens AG)
• Original Assignee: Siemens Rail Automation Corporation
• Inventors: Hoelscher, James R.
• Primary Examiner(s): Le, John H
• Application Number:
  US12/968,944
• Publication Number:
  US 20110144933A1
• Time in Patent Office: 1,042 Days
• Field of Search: 702/58, 702 64- 67, 702/79, 702/89, 702/177, 702182-186, 702/193, 324/522, 324/537, 324/548, 326/136, 345/76, 345/212, 361/42, 701/29.6, 340/2.1, 340/907
• US Class Current: 702/64
• CPC Class Codes: G01R 15/183 using transformers with a magnetic core
• CPC Class Codes: G01R 35/00 Testing or calibrating of apparatus covered by the other groups of this subclass

Abstract

A system for sensing current that includes a processor and a current sensor coupled to the processor. The current sensor includes a sensor threshold value. The system also includes a current generator coupled to the current sensor. The current generator is operable to generate a test current signal defined by a time-varying linear function. The current sensor is operable to be coupled to an external current source and to output a sensor output signal based on a detected current to the processor. The processor is operable to determine a magnitude of the sensor threshold value based on the sensor output signal.

Claims

1. A system for sensing current, comprising:

a processor;

a current sensor coupled to the processor, the current sensor having a first sensor threshold value and a second sensor threshold value; and

a current generator coupled to the current sensor;

wherein the current generator is operable to generate a time-varying linear test current signal having a first value below the first sensor threshold value and a second value above the second sensor threshold value;

the current sensor is operable to be coupled to an external device and the current generator;

the current sensor is operable to output a sensor output signal to the processor, the sensor output signal being dependent on a first current associated with the current generator and a second current associated with the external device; and

the processor is operable to determine a time between a crossing of the first sensor threshold and a crossing of the second sensor threshold.

2. The system of claim 1, wherein the sensor output signal comprises a pulse having a pulse width based on a magnitude of the first sensor threshold and a magnitude of the second sensor threshold.

3. The system of claim 1, wherein:

the test current signal comprises a starting current value and an ending current value, and

the starting current value and the ending current value have opposite polarities.

4. The system of claim 1, wherein:

the external device has at least one operating state; and

the processor is operable to determine the operating state based on the sensor output signal.

5. The system of claim 1, further comprising a display connected to the processor and operable to display a status of the current sensor.

6. The system of claim 1, wherein the current sensor is a Hall effect sensor.

7. The system of claim 1, wherein the sensor output signal is a digital signal.

8. The system of claim 1, wherein the processor is operable to generate an alert based on the time between the crossing of the first sensor threshold and a crossing of the second sensor threshold.

9. The system of claim 8, further comprising a display operable to display the alert.

10. A method for sensing current, comprising:

applying a time-varying linear test current to a current sensor, the current sensor having a current sensor output being dependent on a current flowing through an external device and the test current, the current sensor having a first sensor threshold value and a second sensor threshold value;

determining a time between a crossing of the first sensor threshold and a crossing of the second sensor threshold.

11. The method of claim 10, wherein:

the test current signal comprises a starting current value and an ending current value, and

the starting current value and the ending current value have opposite polarities.

12. The method of claim 10, further comprising:

determining an operating state of the external device based on the sensor output signal.

13. The method of claim 12, further comprising displaying the operating state.

14. The method of claim 10, further comprising generating an alert based on the time between the crossing of the first sensor threshold and a crossing of the second sensor threshold.

15. The method of claim 14, further comprising displaying the alert.

16. The method of claim 10, wherein the sensor output signal is a digital signal.

17. The method of claim 10, wherein the sensor output signal comprises a pulse having a pulse width based on a magnitude of the first sensor threshold and a magnitude of the second sensor threshold.

18. The method of claim 10, wherein the current sensor is a Hall effect sensor.