Method of detecting abnormal electric current in vehicle apparatus for detecting abnormal electric current in vehicle and power supply apparatus for vehicle

• US 5,994,790 A
• Filed: 04/02/1998
• Issued: 11/30/1999
• Est. Priority Date: 04/04/1997
• Status: Expired due to Term

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Kurita, Kaoru, Umeda, Yukihiko, Nagashima, Yoshikazu
• Primary Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US09/053,764
• Time in Patent Office: 607 Days
• Field of Search: 307/10.1, 307/131, 307/31, 307/30, 361/87, 315/307
• US Class Current: 307/10.1
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02H 3/0935 the timing being determined by numerical means
• CPC Class Codes: H02H 5/041 additionally responsive to excess current H02H5/048 takes precedence
• CPC Class Codes: H02H 5/044 using a semiconductor device to sense the temperature

Abstract

A method of detecting an abnormal electric current in a vehicle to detect passage of an abnormal electric current through an electric wire for establishing the connection between a load to which electric power is supplied and a power source, the method of detecting an abnormal electric current in a vehicle comprising the steps of: (a) detecting values of electric currents which pass through the electric wire at predetermined sampling intervals; (b) counting the number of times in a unit detection period that a sampled electric current having a value larger than a predetermined value is detected and determining passage of an abnormal electric current through the electric wire when the number of counts is larger than a first number of times; and (c) counting the number of times that a sampled electric current having a value larger than the predetermined value is detected in a unit detection period after the unit detection period in terms of time in a case where the number of counts is smaller than the first number of times and except for zero and determining passage of an abnormal electric current through the electric wire when the number of counts is larger than a second number of times.

Claims

1. A method of detecting an abnormal electric current passing through an electric connection between a load to which electric power is supplied and a power source, the method comprising the steps of:

(a) detecting values of electric currents which pass through the electric connection at predetermined sampling intervals;

(b) counting the number of times in a first unit detection period that a sampled electric current having a value larger than a predetermined value is detected and determining that a passage of an abnormal electric current has occurred through the electric connection when the number of counts is larger than a first number of times; and

(c) counting the number of times that the sampled electric current having the value larger than the predetermined value is detected in a second unit detection period, said second unit detection period being after the first unit detection period in terms of times in a case where the number of counts is smaller than the first number of times and is not zero, and determining that the passage of the abnormal electric current has occurred through the electric connection when the number of counts is larger than a second number of times.

2. The method of detecting an abnormal electric current according to claim 1, wherein

when the number of counts in the unit detection period in the first determining step (b) or second determining step (c) is zero, a determination is made that the abnormal electric current is not passing through the electric connection, and

when the number of counts in the second determining step is smaller than the second number of times and is not zero, processes similar to the first determining step (b) and the second determining step (c) are repeated in unit detection periods following the second unit detection period in the second determining step (c).

3. The method of detecting an abnormal electric current according to claim 1, wherein the processes in the first determining step (b) and second determining step (c) are not performed until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started, and the first determining step (b) and second determining step (c) are performed after the predetermined period of time has elapsed.

4. The method of detecting an abnormal electric current according to claim 1, wherein the second number of times in the second determining step (b) is smaller than the first number of times.

5. The method of detecting an abnormal electric current according to claim 1, wherein the first and second numbers of times are determined in consideration of a damage characteristic of the electric connection.

6. A method of detecting an abnormal electric current passing through an electric connection between a load to which electric power is supplied and a power source, the method comprising the steps of:

(a) detecting values of electric currents which pass through the electric connection at predetermined sampling intervals;

(b) assigning a first weighting coefficient to the number of times that a sampled electric current having a value larger than a first threshold value is detected in a first unit detection period, assigning a second weighting coefficient smaller than the first weighting coefficient to the number of times that a sampled electric current having a value smaller than the first threshold value and not smaller than a second threshold value the second threshold value being smaller than the first threshold value, is detected, adding up the numbers of times that weight assignment is performed, and determining that an abnormal electric current is passing through the electric connection when the added numbers of times that the weight assignment is performed are larger than a first number of times; and

(c) when the added numbers of times that the weight assignment is performed in the first unit detection period is smaller than a first number of times and is not zero, assigning the first weighting coefficient to the number of times that a sampled electric current having a value larger than the first threshold value is detected in a second unit detection period following the first unit detection period in terms of time, assigning the second weighting coefficient to the number of times that a sampled electric current having a value smaller than the first threshold value and not smaller than the second threshold value is detected, adding up the numbers of times that the weight assignment is performed, and determining that an abnormal electric current is passing through the electric wire when the added numbers of times that the weight assignment is performed is larger than a second number of times.

7. The method of detecting an abnormal electric current according to claim 6, wherein

when the number of counts in the first unit detection period in the first determining step (b) or the second determining step (c) is zero, a determination is made that the abnormal electric current is not passing through the electric connection, and

when the number of counts in the second determining step is smaller than the second number of times and is not zero, processes similar to the first determining step (b) and the second determining step (c) are repeated in unit detection period following the second unit detection period in the second determining step (c).

8. The method of detecting an abnormal electric current according to claim 6, wherein the processes in the first determining step (b) and the second determining step (c) are not performed until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started, and the first determining step (b) and the second determining step (c) are performed after the predetermined period of time has elapsed.

9. The method of detecting an abnormal electric current according to claim 6, wherein the second number of times in the second determining step (b) is smaller than the first number of times.

10. The method of detecting an abnormal electric current according to claim 6, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

12. The apparatus for detecting an abnormal electric current according to claim 7, wherein the abnormality determination means determines that no abnormal electric current is passing through the electric connection when the number of counts in the certain period of time or the number of counts in the period of time following the certain period of time in terms of time is zero and repeats the abnormal-electric-current determination in accordance with the number of counts in the latter period of time when the number of counts in the period of time following the certain period of time in terms of time is smaller than the second number of times and is not zero.

11. An apparatus for detecting an abnormal electric current passing through an electric connection when electric power is supplied from a power source portion to a load through the electric connection, the apparatus comprising:

electric-current detection means for detecting an electric current value which is passing through the electric connection;

sampling means for sampling the detected electric current values at predetermined sampling intervals;

comparison means for subjecting each sampled electric current value and a predetermined threshold value to a comparison;

a counter for counting the number of times that the sampled electric current values are larger than the predetermined threshold value in each predetermined period of time; and

abnormality determination means for determining that a passage of an abnormal electric current through the electric connection has occurred, when the number of counts in a certain period of time in each of the predetermined periods of time is not smaller than a first number of times, and determining that the passage of an abnormal electric current through the electric connection has occurred, when the number of counts in the certain detection period is smaller than the first number of times and is not zero and when a number of counts in a period of time following the certain period of time in terms of time is larger than a second number of times.

13. The apparatus for detecting an abnormal electric current according to claim 11, wherein the determination of the abnormal electric current is not performed until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

14. The apparatus for detecting an abnormal electric current according to claim 11, wherein the second number of times is smaller than the first number of times.

15. The apparatus for detecting an abnormal electric current according to claim 11, wherein the first and second numbers of times are determined in consideration of a damage characteristic of the electric connection.

16. An apparatus for detecting an abnormal electric current passing through an electric connection when electric power is supplied from a power source portion to a load through the electric connection, the apparatus comprising:

electric-current detection means for detecting an electric current value which is passing through the electric connection;

sampling means for sampling the detected electric current values at predetermined sampling intervals;

comparison means for subjecting each sampled electric current value, a first threshold value and a second threshold value smaller than the first threshold value to comparisons;

first and second counters for counting the number of times of the sampled electric current values not smaller than the first threshold value and the number of times of the sampled electric current values smaller than the first threshold value and not smaller than the second threshold value respectively in each predetermined period of time;

weight addition means for assigning a first weighting coefficient to the number of times counted by the first counter, assigning a second weighting coefficient smaller than the first weighting coefficient to the number of times counted by the second counter and adding up the numbers of times that the weight assignment is performed; and

abnormality determination means for determining passage of an abnormal electric current through the electric wire when the number of times that the weight assignment is performed in a certain period of time is not smaller than a first number of times and determining passage of an abnormal electric current through the electric wire when the number of times that the weight assignment is performed in the certain detection period is smaller than the first number of times and is not zero and when a number of times that the weight assignment is performed in a period of time following the certain period of time in terms of time is larger than a second number of times.

17. The apparatus for detecting an abnormal electric current according to claim 16, wherein the abnormality determination means determines that no abnormal electric current is passing through the electric connection when the number of counts in the certain period of time in terms of time is zero and repeats the abnormal-electric-current determination in accordance with the number of counts in the latter period of time when the number of time following the certain period of time in terms of time is smaller than the second number of times and is not zero.

18. The apparatus for detecting an abnormal electric current according to claim 16, wherein the determination of the abnormal electric current is not performed until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

19. The apparatus for detecting an abnormal electric current according to claim 16, wherein the second number of times is smaller than the first number of times.

20. The apparatus for detecting an abnormal electric current according to claim 16, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

21. A power supply apparatus arranged such that electric power is supplied from a power source portion to a load through an electric connection, the power supply apparatus comprising:

electric-current detection means for detecting an electric current value which is passing through the electric connection;

sampling means for sampling the detected electric current values at predetermined sampling intervals;

comparison means for subjecting each sampled electric current value and a predetermined threshold value to a comparison;

a counter for counting the number of times that the sampled electric current values are larger than the predetermined value in each predetermined period of time;

abnormality determination means for determining passage of an abnormal electric current through the electric connection when the number of counts in a certain period of time in each of the predetermined periods of time is not smaller than a first number of times and determining passage of an abnormal electric current through the electric wire when the number of counts in the certain detection period is smaller than the first number of times and is not zero and when a number of counts in a period of time following the certain period of time in terms of time is larger than a second number of times; and

control means for interrupting an electric current which passes through the electric connection by switching off a switch, provided on the electric connection for establishing the connection between the power source portion and the loads when passage of the abnormal electric current has been determined by the abnormality determination means.

22. The power supply apparatus according to claim 21, wherein the switch is not switched off by the control means until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

23. The power supply apparatus according to claim 21, wherein the second number of times is smaller than the first number of times.

24. The power supply apparatus according to claim 21, wherein the first and second numbers of times are determined in consideration of a damage characteristic of the electric connection.

45. The power supply apparatus according to claim 21, wherein the second number of times is smaller than the first number of times.

46. The power supply apparatus according to claim 21, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

25. A power supply apparatus arranged such that electric power is supplied from a power source portion to a load through an electric connection, the power supply apparatus comprising:

electric-current detection means for detecting an electric current value which is passing through the electric connection;

sampling means for sampling the detected electric current values at predetermined sampling intervals;

comparison means for subjecting each sampled electric current value, a first threshold value and a second threshold value to comparisons;

counters for counting the number of times that the sampled electric current values are not smaller than the first threshold value and the number of times that the sampled electric current values are not smaller than the second threshold value, respectively, the second threshold value being smaller than the first threshold value;

weight addition means for assigning a first weighting coefficient to the number of times that the sampled electric current values are larger than the first threshold value, assigning a second weighting coefficient smaller than the first weighting coefficient to the number of times that the sampled electric current values are smaller than the first threshold value and not smaller than the second threshold value and adding up the number of times that the weight assignment is performed;

abnormality determination means for determining passage of an abnormal electric current through the electric connection when the number of counts in a certain period of time is not smaller than a first number of times and determining passage of an abnormal electric current through the electric connection when the number of counts in the certain detection period is smaller than the first number of times and is not zero and when a number of counts in a period of time following the certain period of time in terms of time is larger than a second number of times; and

control means for interrupting an electric current which passes through the electric connection by switching off a switch, provided on the electric connection for establishing the connection between the power source portion and the load, when passage of the abnormal electric current has been determined by the abnormality determination means.

26. The power supply apparatus according to claim 25, wherein the switch is not switched off by the control means until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

27. The power supply apparatus according to claim 25, wherein the second number of times is smaller than the first number or times.

28. The power supply apparatus according to claim 25, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

29. An apparatus for detecting an abnormal electric current passing through an electric connection when electric power is supplied from a power source portion to a load through the electric connection, the apparatus comprising:

an electric-current detector which detects an electric current value which is passing through the electric connection;

a sampling circuit which samples the detected electric current values at predetermined sampling intervals;

a comparison circuit which subjects each sampled electric current value and a predetermined threshold value to a comparison;

a counter for counting the number of times that the sampled electric current values are larger than the predetermined threshold value in each predetermined period of time; and

an abnormality determination circuit which determines that a passage of an abnormal electric current through the electric connection has occurred, when the number of counts in a certain period of time in each of the predetermined periods of time is not smaller than a first number of times, and determines that the passage of an abnormal electric current through the electric connection has occurred, when the number of counts in the certain detection period is smaller than the first number of times and is not zero and when a number of counts in a period of time following the certain period of time in terms of time is larger than a second number of times.

30. The apparatus for detecting an abnormal electric current according to claim 29, wherein the abnormality determination circuit determines that no abnormal electric current is passing through the electric connection when the number of counts in the certain period of time in terms of time is zero and repeats the abnormal-electric-current determination in accordance with the number of counts in the latter period of time when the number of time following the certain period of time in terms of time is smaller than the second number of times and is not zero.

31. The apparatus for detecting an abnormal electric current according to claim 29, wherein the determination of the abnormal electric current is not performed until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

32. The apparatus for detecting an abnormal electric current according to claim 29, wherein the second number of times is smaller than the first number of times.

33. The apparatus for detecting an abnormal electric current according to claim 29, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

34. An apparatus for detecting an abnormal electric current passing through an electric connection when electric power is supplied from a power source portion to a load through the electric connection, the apparatus comprising:

an electric-current detector which detects an electric current value which is passing through the electric connection;

a sampling circuit which samples the detected electric current values at predetermined sampling intervals;

a comparison circuit which subjects each sampled electric current value, a first threshold value and a second threshold value smaller than the first threshold value to comparisons;

first and second counters for counting the number of times of the sampled electric current values not smaller than the first threshold value and the number of times of the sampled electric current values smaller than the first threshold value and not smaller than the second threshold value respectively in each predetermined period of time;

an adder which assigns a first weighting coefficient to the number of times counted by the first counter, assigns a second weighting coefficient smaller than the first weighting coefficient to the number of times counted by the second counter and adds up the numbers of times that the weight assignment is performed; and

an abnormality determination circuit which determines passage of an abnormal electric current through the electric wire when the number of times that the weight assignment is performed in a certain period of time is not smaller than a first number of times, and determines passage of an abnormal electric current through the electric wire when the number of times that the weight assignment is performed in the certain detection period is smaller than the first number of times and is not zero and when a number of times that the weight assignment is performed in a period of time following the certain period of time in terms of time is larger than a second number of times.

35. The apparatus for detecting an abnormal electric current according to claim 34, wherein the abnormality determination circuit determines that no abnormal electric current is passing through the electric connection when the number of counts in the certain period of time in terms of time is zero and repeats the abnormal-electric-current determination in accordance with the number of counts in the latter period of time when the number of time following the certain period of time in terms of time is smaller than the second number of times and is not zero.

36. The apparatus for detecting an abnormal electric current according to claim 34, wherein the determination of the abnormal electric current is not performed until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

37. The apparatus for detecting an abnormal electric current according to claim 34, wherein the second number of times is smaller than the first number of times.

38. The apparatus for detecting an abnormal electric current according to claim 34, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

39. A power supply apparatus arranged such that electric power is supplied from a power source portion to a load through an electric connection, the power supply apparatus comprising:

an electric-current detector which detects an electric current value which is passing through the electric connection;

a sampling circuit which samples the detected electric current values at predetermined sampling intervals;

a comparison circuit which subjects each sampled electric current value and a predetermined threshold value to a comparison;

a counter for counting the number of times that the sampled electric current values are larger than the predetermined value in each predetermined period of time;

an abnormality determination circuit which determines passage of an abnormal electric current through the electric connection when the number of counts in a certain period of time in each of the predetermined periods of time is not smaller than a first number of times, and determines passage of an abnormal electric current through the electric wire when the number of counts in the certain detection period is smaller than the first number of times and is not zero and when a number of counts in a period of time following the certain period of time in terms of time is larger than a second number of times; and

a controller which interrupts an electric current which passes through the electric connection by switching off a switch, provided on the electric connection for establishing the connection between the power source portion and the load, when passage of the abnormal electric current has been determined by the abnormality determination circuit.

40. The power supply apparatus according to claim 39, wherein the switch is not switched off by the controller until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.

41. The power supply apparatus according to claim 39, wherein the second number of times is smaller than the first number of times.

42. The power supply apparatus according to claim 39, wherein the first and second number of times are determined in consideration of a damage characteristic of the electric connection.

43. A power supply apparatus arranged such that electric power is supplied from a power source portion to a load through an electric connection, the power supply apparatus comprising:

an electric-current detector which detects an electric current value which is passing through the electric connection;

a sampling circuit which samples the detected electric current values at predetermined sampling intervals;

a comparison circuit which subjects each sampled electric current value, a first threshold value and a second threshold value to comparisons;

counters for counting the number of times that the sampled electric current values are not smaller than the first threshold value and the number of times that the sampled electric current values are not smaller than the second threshold value, respectively, the second threshold value being smaller than the first threshold value;

an adder which assigns a first weighting coefficient to the number of times that the sampled electric current values are larger than the first threshold value, assigns a second weighting coefficient smaller than the first weighting coefficient to the number of times that the sampled electric current values are smaller than the first threshold value and not smaller than the second threshold value, and adds up the number of times that the weight assignment is performed;

an abnormality determination circuit which determines passage of an abnormal electric current through the electric connection when the number of counts in a certain period of time is not smaller than a first number of times, and determines passage of an abnormal electric current through the electric connection when the number of counts in the certain detection period is smaller than the first number of times and is not zero and when a number of counts in a period of time following the certain period of time in terms of time is larger than a second number of times; and

a controller which interrupts an electric current which passes through the electric connection by switching off a switch, provided on the electric connection for establishing the connection between the power source portion and the load, when passage of the abnormal electric current has been determined by the abnormality determination circuit.

44. The power supply apparatus according to claim 43, wherein the switch is not switched off by the controller until a predetermined period of time elapses from the moment in time at which supply of electric power to the load has been started.