Sensor fault detection using paired sample correlation

• US 10,698,033 B2
• Filed: 12/21/2017
• Issued: 06/30/2020
• Est. Priority Date: 12/21/2017
• Status: Active Grant

• Current Assignee: Robert Bosch Battery Systems LLC (Robert Bosch GmbH), Robert Bosch GmbH
• Original Assignee: Robert Bosch Battery Systems LLC (Robert Bosch GmbH)
• Inventors: Riley, Blake Joseph, Brown, Carlton
• Primary Examiner(s): Koval, Melissa J
• Assistant Examiner(s): Nguyen, Trung
• Application Number:
  US15/850,521
• Publication Number:
  US 20190195952A1
• Time in Patent Office: 922 Days
• Field of Search: 324425-435, 324500, 3247503, 32475704, 32476203, 324600, 324663, 324671, 324200, 32420713, 32420722, 324239, 324241, 324515, 324520, 324530, 324 7611, 324105-124
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 35/00 Testing or calibrating of apparatus covered by the other groups of this subclass
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for current sensor fault detection in a battery system comprises receiving a sequence of battery voltage samples from a voltage sensor configured to measure a battery voltage of a battery and a sequence of battery current samples from a current sensor configured to measure a battery current of the battery; determining a change in the battery voltage samples over a predetermined number of samples and a change in the battery current samples over the predetermined number of samples; checking whether a ratio of the change in the battery voltage samples and the change in the battery current samples is within an expected range for one of (i) a resistance of the battery and (ii) a conductance of the battery; and detecting a fault in the current sensor based on whether the ratio is within the expected range.

Claims

1. A method of current sensor fault detection comprising:

receiving a sequence of battery voltage samples from a voltage sensor configured to measure a battery voltage of a battery and a sequence of battery current samples from a current sensor configured to measure a battery current of the battery, the sequence of battery voltage samples and the sequence of battery current samples both having been measured while the battery current was non-zero;

determining a change in the battery voltage samples over a predetermined number of samples and a change in the battery current samples over the predetermined number of samples;

checking whether a ratio of the change in the battery voltage samples and the change in the battery current samples is within an expected range for one of (i) a resistance of the battery and (ii) a conductance of the battery; and

detecting a fault in the current sensor based on whether the ratio is within the expected range.

2. The method according to claim 1, the determining of the change in the battery voltage samples and the change in the battery current samples further comprising:

determining the change in the battery voltage samples as a difference between a value of the battery voltage samples at a first time step and a value of the battery voltage samples at a second time step, the second time step being a first predetermined number of time steps after the first time step; and

determining the change in the battery current samples as a difference between a value of the battery current samples at a third time step and a value of the battery current samples at a fourth time step, the fourth time step being the first predetermined number of time steps after the third time step, the third time step being a second predetermined number of time steps before or after the first time step.

3. The method according to claim 1 further comprising:

receiving a battery temperature measurement from a temperature sensor configured to measure a temperature of the battery; and

determining the expected range based on the battery temperature measurement.

4. The method according to claim 1, the detecting further comprising:

detecting the fault based on the ratio being outside the expected range.

5. The method according to claim 1 further comprising:

repeating the steps of determining and checking for successive time steps of the battery voltage samples and battery current samples;

storing, for each repetition of the check, whether the ratio is outside the expected range;

determining, after a predetermined number of repetitions of the check, a number of times of the predetermined number of repetitions that the ratio was outside the expected range; and

detecting the fault in response to the number of times exceeding a predetermined threshold.

6. The method according to claim 5 further comprising:

adjusting at least one of the expected range and the predetermined threshold based on at least one of (i) cell aging of the battery, (ii) a state of charge of the battery, (iii) a polarity of the battery current, and (iv) a phase difference between the battery current and battery voltage.

7. The method according to claim 1, the checking further comprising:

only performing the check if at least one of (i) a battery temperature of the battery exceeds a minimum temperature threshold, (ii) the change in the battery voltage samples exceeds a minimum voltage change threshold, and (iii) a current value of the battery current samples exceeds a minimum current threshold.

8. The method according to claim 7 further comprising:

adjusting at least one of the minimum temperature threshold, the minimum voltage change threshold, and the minimum current threshold based on at least one of (i) cell aging of the battery, (ii) a state of charge of the battery, (iii) a polarity of the battery current, and (iv) a phase difference between the battery current and battery voltage.

9. The method according to claim 1 further comprising:

operating, in response to detecting the fault, an output device to generate one of (i) an audible alert and (ii) a visual alert.

10. The method according to claim 1 further comprising:

operating, in response to detecting the fault, at least one switch to disconnect the battery from at least one load.

11. A battery system comprising:

a battery operably connected to provide power to at least one load;

a voltage sensor configured to measure a battery voltage of the battery;

a current sensor configured to measure a battery current of the battery; and

a controller operably connected to the voltage sensor and the current sensor, the controller being configured to;

receive a sequence of battery voltage samples from the voltage sensor and a sequence of battery current samples from the current sensor, the sequence of battery voltage samples and the sequence of battery current samples both having been measured while the battery current was non-zero;

determine a change in the battery voltage samples over a predetermined number of samples and a change in the battery current samples over the predetermined number of samples;

check whether a ratio of the change in the battery voltage samples and the change in the battery current samples is within an expected range for one of (i) a resistance of the battery and (ii) a conductance of the battery; and

detect the fault in the current sensor based on whether the ratio is within the expected range.

12. The battery system according to claim 11, the controller being further configured to:

determine the change in the battery voltage samples as a difference between a value of the battery voltage samples at a first time step and a value of the battery voltage samples at a second time step, the second time step being a first predetermined number of time steps after the first time step; and

determine the change in the battery current samples as a difference between a value of the battery current samples at a third time step and a value of the battery current samples at a fourth time step, the fourth time step being the first predetermined number of time steps after the third time step, the third time step being a second predetermined number of time steps after the first time step.

13. The battery system according to claim 11 further comprising:

a temperature sensor configured to measure a temperature of the battery,

wherein the controller is further configured to;

receive a battery temperature measurement from the temperature sensor; and

determine the expected range based on the battery temperature measurement.

14. The battery system according to claim 11, the controller being further configured to:

detect the fault in response to the ratio being outside the expected range.

15. The battery system according to claim 11, the controller being further configured to:

repeat the determination and the check for successive time steps of the battery voltage samples and battery current samples;

store, for each repetition of the check, whether the ratio is outside the expected range;

determine, after a predetermined number of repetitions of the check, a number of times of the predetermined number of repetitions that the ratio was outside the expected range; and

detect the fault in response to the number of times exceeding a predetermined threshold.

16. The battery system according to claim 15, the controller being further configured to:

adjust at least one of the expected range and the predetermined threshold based on at least one of (i) cell aging of the battery, (ii) a state of charge of the battery, (iii) a polarity of the battery current, and (iv) a phase difference between the battery current and battery voltage.

17. The battery system according to claim 11, the controller being further configured to:

only perform the check if at least one of (i) a battery temperature of the battery exceeds a minimum temperature threshold, (ii) the change in the battery voltage samples exceeds a minimum voltage change threshold, and (iii) a current value of the battery current samples exceeds a minimum current threshold.

18. The battery system according to claim 17, the controller being further configured to:

adjust at least one of the minimum temperature threshold, the minimum voltage change threshold, and the minimum current threshold based on at least one of (i) cell aging of the battery, (ii) a state of charge of the battery, (iii) a polarity of the battery current, and (iv) a phase difference between the battery current and battery voltage.

19. The battery system according to claim 11, the controller being further configured to:

operate, in response to detecting the fault, an output device to generate one of (i) an audible alert and (ii) a visual alert.

20. The battery system according to claim 11, the controller being further configured to:

operate, in response to detecting the fault, at least one switch to disconnect the battery from the at least one load.