Method and apparatus for electrical component life estimation

Patent metadata

Field	Value
Publication number	US-9869722-B1
Application number	US-201615293655-A
Country	US
Kind code	B1
Filing date	Oct 14, 2016
Priority date	Sep 22, 2016
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

Systems and methods for estimating electrical component degradation caused by an operating parameter that stresses the component in a series of stress cycles, in which cycle count values are maintained which individually correspond to a range of values of the operating parameter, and a plurality of maximum cycle values are stored, which individually correspond to one of the ranges and represent the number of stress cycles in the corresponding range at which the component is expected to have a user defined failure probability value. For a given stress cycle, one of the count values is incremented that corresponds to the range that includes a measured or sensed value, and a cumulative degradation value for the electrical system component is computed as a sum of ratios of the individual count values to the corresponding maximum cycle values.

First claim

The following is claimed:

1. A method for estimating degradation of an electrical system component caused by an operating parameter that stresses the electrical system component for each of series of stress cycles, the method comprising:
maintaining by an apparatus a plurality of cycle count values, each individual cycle count value corresponding to one of a plurality of non-overlapping ranges of values of the operating parameter;
storing by the apparatus a plurality of maximum cycle values, each individual maximum cycle value corresponding to one of the plurality of non-overlapping ranges of values of the operating parameter, each individual maximum cycle value representing a number of stress cycles in the corresponding range of values of the operating parameter at which the electrical system component is expected to have a user defined failure probability value;
for a given stress cycle, receiving by the apparatus from the electrical system a first value representing the operating parameter for the given stress cycle;
for the given stress cycle, incrementing by the apparatus one of the cycle count values that corresponds to the range of values of the operating parameter that includes the first value;
for the given stress cycle, computing by the apparatus a cumulative degradation value for the electrical system component as a sum of a plurality of ratios of the individual cycle count values divided by the corresponding maximum cycle values of the plurality of values of the operating parameter;
computing by the apparatus a predicted remaining time when the electrical system component needs to be replaced using the cumulative degradation value and a filtered use case cumulative degradation accumulation rate; and
selectively generating by the apparatus a first message on an interface of the electrical system, the first message comprising at least a warning generated when the cumulative degradation value for the given stress cycle exceeds a user defined first threshold value.

2. The method of claim 1 , further comprising:
selectively generating a second message on the interface of the electrical system, the second message comprising at least an alarm generated when the cumulative degradation value for the given stress cycle exceeds a user defined second threshold value, the second threshold value being greater than the first threshold value.

3. The method of claim 1 , wherein the electrical system component is a motor drive component.

4. The method of claim 3 , wherein the motor drive component is an insulated gate bipolar transistor (IGBT), and wherein the operating parameter is a junction temperature change.

5. The method of claim 3 , wherein the motor drive component is a capacitor, and wherein the operating parameter is one of a temperature and a voltage.

6. The method of claim 3 , wherein the motor drive component is a fan, and wherein the operating parameter is a fan speed and ambient temperature.

7. The method of claim 3 , wherein the method is implemented in a processor of a motor drive.

8. A non-transitory computer readable medium with computer executable instructions for estimating degradation of an electrical system component caused by an operating parameter that stresses the electrical system component for each of series of stress cycles, the computer readable medium comprising computer-executable instructions which, when executed by a processor, cause the processor to:
maintain a plurality of cycle count values, each individual cycle count value corresponding to one of a plurality of non-overlapping ranges of values of the operating parameter;
store a plurality of maximum cycle values, each individual maximum cycle value corresponding to one of the plurality of non-overlapping ranges of values of the operating parameter, each individual maximum cycle value representing a number of stress cycles in the corresponding range of values of the operating parameter at which the electrical system component is expected to have a user defined failure probability value;
for a given stress cycle, receive a first value representing the operating parameter for the given stress cycle from the electrical system;
for the given stress cycle, increment one of the cycle count values that corresponds to the range of values of the operating parameter that includes the first value;
for the given stress cycle, compute a cumulative degradation value for the electrical system component as a sum of a plurality of ratios of the individual cycle count values divided by the corresponding maximum cycle values of the plurality of values of the operating parameter;
compute a predicted remaining time when the electrical system component needs to be replaced using the cumulative degradation value and a filtered use case cumulative degradation accumulation rate; and
selectively generate a first message on an interface of the electrical system, the first message comprising at least a warning generated when the cumulative degradation value for the given stress cycle exceeds a user defined first threshold value.

9. The non-transitory computer readable medium of claim 8 , further comprising computer-executable instructions which, when executed by the processor, cause the processor to:
selectively generate a second message on the interface of the electrical system, the second message comprising at least an alarm generated when the cumulative degradation value for the given stress cycle exceeds a user defined second threshold value, the second threshold value being greater than the first threshold value.

10. The non-transitory computer readable medium of claim 8 , wherein the electrical system component is a motor drive component.

11. The non-transitory computer readable medium of claim 10 , wherein the motor drive component is an insulated gate bipolar transistor (IGBT), and wherein the operating parameter is a junction temperature change.

12. The non-transitory computer readable medium of claim 10 , wherein the motor drive component is a capacitor, and wherein the operating parameter is one of a temperature and a voltage.

13. The non-transitory computer readable medium of claim 10 , wherein the motor drive component is a fan, and wherein the operating parameter is a fan speed and ambient temperature.

14. A system for estimating degradation of an electrical system component caused by an operating parameter that stresses the electrical system component for each of series of stress cycles, the system comprising:
an electronic memory that stores:
a plurality of cycle count values, each individual cycle count value corresponding to one of a plurality of non-overlapping ranges of values of the operating parameter, and
a plurality of maximum cycle values, each individual maximum cycle value corresponding to one of the plurality of non-overlapping ranges of values of the operating parameter, each individual maximum cycle value representing a number of stress cycles in the corresponding range of values of the operating parameter at which the electrical system component is expected to have a user defined failure probability value; and

a processor programmed to:
for a given stress cycle, receive a first value representing the operating parameter for the given stress cycle from the electrical system,
for the given stress cycle, increment one of the cycle count values that corresponds to the range of values of the operating parameter that includes the first value,
for the given stress cycle, compute a cumulative degradation value for the electrical system component as a sum of a plurality of ratios of the individual cycle count values divided by the corresponding

Assignees

• Rockwell Automation Tech Inc

Inventors

• Morris Garron K

Classifications

• H02P29/60

  Controlling or determining the temperature of the motor or of the drive (H02P29/02 takes precedence) · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02P23/14

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• H02P29/0241

  the fault being an overvoltage · CPC title

• G01R31/2849

  Environmental or reliability testing, e.g. burn-in or validation tests (of individual semiconductors G01R31/2642; of printed circuits boards G01R31/2817; of IC's G01R31/2855) · CPC title