Systems and methods for switch health determination

• US 9,778,319 B2
• Filed: 11/07/2014
• Issued: 10/03/2017
• Est. Priority Date: 11/07/2014
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Inventors: Edwards, William E., Andresen, Anthony F., Gray, Randall C.
• Primary Examiner(s): Vazquez, Arleen M
• Assistant Examiner(s): SHAH, NEEL D
• Application Number:
  US14/536,017
• Publication Number:
  US 20160131713A1
• Time in Patent Office: 1,061 Days
• Field of Search: 324415, 324418, 324422, 307128, 307130, 327 74, 327 77, 327 87
• CPC Class Codes: G01R 19/16566 Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
• CPC Class Codes: G01R 31/3274 Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance measuring contact resistance G01R27/205
• CPC Class Codes: G01R 31/3275 Fault detection or status indication
• CPC Class Codes: G01R 31/3277 of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches

Abstract

The embodiments described herein provide systems and methods for determining the health status of a sensed switch. In general, the embodiments described herein determine a measure of a health status of the sensed switch by comparing a voltage on the sensed switch, ascertaining a first comparator state under one test condition and ascertaining a second comparator state under a second test condition. The first comparator state and the second comparator state are and then compared to determine the measure of the health status of the sensed switch.

Claims

1. A switch health determination system, comprising:

a comparator coupled to a switch, the comparator configured to selectively compare a voltage on the switch to a first threshold voltage and a second threshold voltage, wherein the first and second threshold voltages have different values; and

a controller coupled to the comparator, the controller configured to ascertain a first comparator state when the first threshold voltage is provided to the comparator and to ascertain a second comparator state when the second threshold voltage is provided to the comparator, the controller further configured to compare the first comparator state to the second comparator state and to determine a measure of health status of the switch based at least in part on the comparing of the first comparator state to the second comparator state.

2. The switch health determination system of claim 1 further comprising:

a current source, the current source coupled to the switch and configured to supply current to the switch.

3. The switch health determination system of claim 1 further comprising:

a variable threshold voltage source, wherein the variable threshold voltage source is coupled to the comparator and the controller, and wherein the variable threshold voltage source is configured to selectively apply the first threshold voltage and the second threshold voltage to the comparator as directed by the controller.

4. The switch health determination system of claim 3 wherein the controller is further configured to determine a value for the second threshold voltage based at least in part on the ascertained first comparator state.

5. The switch health determination system of claim 4 wherein the controller is configured to determine the value for the second threshold voltage to be higher than the first threshold voltage if the ascertained first comparator state indicates the switch is open wherein the controller is to determine the value for the second threshold voltage to be lower than the first threshold voltage if the ascertained first comparator state indicates the switch is closed.

6. The switch health determination system of claim 1 wherein the first threshold voltage is further utilized by the controller to read a state of the switch during operation of the switch.

7. The switch health determination system of claim 1 wherein the measure of health status is used to provide an indication that the switch should be replaced.

8. The switch health determination system of claim 1 wherein the controller is further configured to increase a threshold voltage used to read a state of the switch in response to the measure of the health status of the switch indicating excessive closed-state resistance in the switch, and configured to decrease the threshold voltage used to read the state of the switch in response to the measure of the health status of the switch indicating excessive open-state current leakage in the switch.

9. A switch health determination system, comprising:

a comparator coupled to a switch, the comparator configured to selectively compare a voltage on the switch to a first threshold voltage and a second threshold voltage, wherein the first and second threshold voltages have different values;

a controller coupled to the comparator, the controller configured to ascertain a first comparator state when the first threshold voltage is provided to the comparator and to ascertain a second comparator state when the second threshold voltage is provided to the comparator, the controller further configured to compare the first comparator state to the second comparator state and to determine a measure of health status of the switch based at least in part on the comparing of the first comparator state to the second comparator state; and

a variable threshold voltage source, wherein the variable threshold voltage source is coupled to the comparator and the controller, and wherein the variable threshold voltage source is configured to selectively apply the first threshold voltage and the second threshold voltage to the comparator as directed by the controller.

10. The switch health determination system of claim 9 further comprising:

a current source, the current source coupled to the switch and configured to supply current to the switch.

11. The switch health determination system of claim 9 wherein the controller is further configured to determine a value for the second threshold voltage based at least in part on the ascertained first comparator state.

12. The switch health determination system of claim 11 wherein the controller is configured to determine the value for the second threshold voltage to be higher than the first threshold voltage if the ascertained first comparator state indicates the switch is open wherein the controller is to determine the value for the second threshold voltage to be lower than the first threshold voltage if the ascertained first comparator state indicates the switch is closed.

13. The switch health determination system of claim 9 wherein the first threshold voltage is further utilized by the controller to read a state of the switch during operation of the switch.

14. The switch health determination system of claim 9 wherein the controller is further configured to increase a threshold voltage used to read a state of the switch in response to the measure of the health status of the switch indicating excessive closed-state resistance in the switch, and configured to decrease the threshold voltage used to read the state of the switch in response to the measure of the health status of the switch indicating excessive open-state current leakage in the switch.

15. A switch health determination system, comprising:

a current source, the current source coupled to the switch and configured to supply current to the switch;

a comparator coupled to a switch, the comparator configured to selectively compare a voltage on the switch resulting from the current supplied to the switch to a first threshold voltage and a second threshold voltage, wherein the first and second threshold voltages have different values; and

a controller coupled to the comparator, the controller configured to ascertain a first comparator state when the first threshold voltage is provided to the comparator and to ascertain a second comparator state when the second threshold voltage is provided to the comparator, the controller further configured to compare the first comparator state to the second comparator state and to determine a measure of health status of the switch based at least in part on the comparing of the first comparator state to the second comparator state.

16. The switch health determination system of claim 15 further comprising:

a variable threshold voltage source, wherein the variable threshold voltage source is coupled to the comparator and the controller, and wherein the variable threshold voltage source is configured to selectively apply the first threshold voltage and the second threshold voltage to the comparator as directed by the controller.

17. The switch health determination system of claim 16 wherein the controller is further configured to determine a value for the second threshold voltage based at least in part on the ascertained first comparator state.

18. The switch health determination system of claim 17 wherein the controller is configured to determine the value for the second threshold voltage to be higher than the first threshold voltage if the ascertained first comparator state indicates the switch is open wherein the controller is to determine the value for the second threshold voltage to be lower than the first threshold voltage if the ascertained first comparator state indicates the switch is closed.

19. The switch health determination system of claim 15 wherein the first threshold voltage is further utilized by the controller to read a state of the switch during operation of the switch.

20. The switch health determination system of claim 15 wherein the controller is further configured to increase a threshold voltage used to read a state of the switch in response to the measure of the health status of the switch indicating excessive closed-state resistance in the switch, and configured to decrease the threshold voltage used to read the state of the switch in response to the measure of the health status of the switch indicating excessive open-state current leakage in the switch.