Methods for switch health determination

Patent metadata

Field	Value
Publication number	US-10649033-B2
Application number	US-201715720057-A
Country	US
Kind code	B2
Filing date	Sep 29, 2017
Priority date	Nov 7, 2014
Publication date	May 12, 2020
Grant date	May 12, 2020

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.

First claim

What is claimed is:

1. A method performed by a switch health determination system for determining a health status of a switch, the method comprising:
selectively comparing, by a comparator coupled to the switch, 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;
ascertaining a first comparator state when the first threshold voltage is provided to the comparator, and ascertaining a second comparator state when the second threshold voltage is provided to the comparator;
comparing the first comparator state to the second comparator state;
determining 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
adjusting a threshold voltage used to read a state of the switch in response to the measure of the health status of the switch.

2. The method of claim 1 further comprising:
selectively applying, by a variable threshold voltage source coupled to the comparator, the first threshold voltage and the second threshold voltage to the comparator as directed by a controller.

3. The method of claim 2 further comprising:
determining a value for the second threshold voltage based at least in part on the ascertained first comparator state.

4. The method of claim 3 , further comprising:
determining the value for the second threshold voltage to be higher than the first threshold voltage when the ascertained first comparator state indicates the switch is open; and
determining the value for the second threshold voltage to be lower than the first threshold voltage when the ascertained first comparator state indicates the switch is closed.

5. The method of claim 1 further comprising:
utilizing the first threshold voltage to read a state of the switch during operation of the switch.

6. The method of claim 1 further comprising:
using the measure of health status to provide an indication that the switch should be replaced.

7. The method of claim 1 , wherein adjusting the threshold voltage comprises:
increasing 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 closed-state resistance in the switch; and
decreasing 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.

8. A method performed by a switch health determination system for determining a health status of a switch, the method comprising:
supplying, by a current source, current to the switch;
selectively comparing, by a comparator coupled to the switch, 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;
ascertaining a first comparator state when the first threshold voltage is provided to the comparator;
ascertaining a second comparator state when the second threshold voltage is provided to the comparator;
comparing the first comparator state to the second comparator state;
determining 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
adjusting a threshold voltage used to read a state of the switch in response to the measure of the health status of the switch.

9. The method of claim 8 further comprising:
selectively applying, by a variable threshold voltage source, the first threshold voltage and the second threshold voltage to the comparator as directed by a controller.

10. The method of claim 8 further comprising:
determining a value for the second threshold voltage based at least in part on the ascertained first comparator state.

11. The method of claim 10 further comprising:
determining the value for the second threshold voltage to be higher than the first threshold voltage when the ascertained first comparator state indicates the switch is open; and
determining the value for the second threshold voltage to be lower than the first threshold voltage when the ascertained first comparator state indicates the switch is closed.

12. The method of claim 8 further comprising:
utilizing the first threshold voltage to read a state of the switch during operation of the switch.

13. The method of claim 8 , wherein adjusting the threshold voltage comprises:
increasing 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 closed-state resistance in the switch; and
decreasing 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.

Assignees

• Nxp Usa Inc

Inventors

• Edwards William E
• Andresen Anthony F
• Gray Randall C

Classifications

• G01R31/3275

  Fault detection or status indication · CPC title

• G01R31/3277

  of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches · CPC title

• G01R19/16566

  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 title

• G01R31/3274 Primary

  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 title