Fault detection in a motor vehicle charging system

• US 6,194,877 B1
• Filed: 08/02/1999
• Issued: 02/27/2001
• Est. Priority Date: 08/02/1999
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Judge, Alan Francis, Deljevic, Zeljko, Renehan, John Francis
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/365,986
• Time in Patent Office: 575 Days
• Field of Search: 322/17, 322/22, 322/23, 322/24, 322/28, 322/36, 322/18, 320/149, 320/156, 320/162
• US Class Current: 322/28
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/54 Testing for continuity
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/14 for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle

Abstract

A fault detection method is disclosed for a motor vehicle charging system including a generator and an electrical component coupled to receive electrical current from the generator. In one embodiment, the method comprises sensing a first voltage at an output of the generator and sensing a second voltage at the electrical component and, if the first voltage and the second voltage differ by more than a predetermined amount, reducing or suspending output of electrical current from the generator. One advantage of the method disclosed herein is in its ability to diagnose a fault in an electrical connection at the output of a motor vehicle generator, where the fault manifests itself as a high resistance connection.

Claims

1. A fault detection method for a motor vehicle charging system including a generator and an electrical component coupled to receive electrical current from an output of said generator, said method comprising the steps of:

(a) sensing a first voltage at an output of said generator;

(b) sensing a second voltage at said electrical component; and

(c) comparing a difference of said first voltage and said second voltage to a predetermined voltage, said predetermined voltage indicative of a high resistance connection between said output of said generator and said component; and

(d) if said difference is greater than said predetermined voltage, reducing or suspending output of electrical current from said generator.

2. A fault detection method as recited in claim 1, further comprising:

(e) a predetermined period of time after reducing or suspending output of electrical power from said generator, ending said reduction or suspension and repeating said steps (a) through (d).

3. A fault detection method as recited in claim 2, further comprising:

after performing said step (e) for a predetermined number of times, logging a diagnostic code in memory and/or illuminating a diagnostic indicator.

4. A fault detection method as recited in claim 2, wherein said electrical component is a battery.

5. A fault detection method as recited in claim 2, wherein:

said generator is controlled by a voltage regulator which is responsively coupled to a powertrain controller; and

said step of reducing or suspending output of electrical current from said generator comprises the powertrain controller providing a signal to the voltage regulator commanding such reduction or suspension.

6. A fault detection method as recited in claim 2, wherein:

said generator is controlled by a voltage regulator which receives a commanded voltage from a powertrain controller; and

said step of reducing or suspending output of electrical current from said generator comprises the powertrain controller reducing said commanded voltage.

7. A fault detection method as recited in claim 6, wherein:

said steps (a) and (b) are performed by said voltage regulator; and

if said first voltage and said second voltage differ by more than said predetermined amount, said voltage regulator provides a fault signal to said powertrain controller.

8. A fault detection method as recited in claim 2, wherein:

said generator is controlled by a voltage regulator which receives a commanded voltage from a powertrain controller;

said steps (a) and (b) are performed by said voltage regulator; and

if said first voltage and said second voltage differ by more than said predetermined amount, said voltage regulator provides a fault signal to said powertrain controller.

9. A fault detection method as recited in claim 2, wherein said predetermined amount is a function of an output current of said generator.

10. A fault detection method as recited in claim 5, wherein said predetermined amount is a function of an output current of said alternator.

11. A fault detection method as recited in claim 7, wherein said predetermined amount is a function of an output current of said alternator.

12. A fault detection method for a motor vehicle charging system including a generator and an electrical component coupled to receive electrical current from said generator, said method comprising the steps of:

(a) sensing a first voltage at an output of said generator;

(b) sensing a second voltage at said electrical component; and

(c) if said first voltage and said second voltage differ by more than a predetermined amount, said predetermined amount being a function of an output current of said generator, reducing or suspending output of electrical current from said generator.

13. A fault detection method as recited in claim 12, further comprising:

(d) a predetermined time after reducing or suspending output of electrical power from said generator, ending said reduction or suspension and repeating said steps (a) through (c).

14. A fault detection method as recited in claim 13, wherein:

said generator is controlled by a voltage regulator which is responsively coupled to a powertrain controller; and

said step of reducing or suspending output of electrical current from said generator comprises the powertrain controller providing a signal to the voltage regulator commanding such reduction or suspension.

15. A fault detection method as recited in claim 14, wherein:

said steps (a) and (b) are performed by said voltage regulator; and

if said first voltage and said second voltage differ by more than said predetermined amount, said voltage regulator provides a fault signal to said powertrain controller.

16. A fault detection method as recited in claim 15, further comprising:

after performing said step (d) for a predetermined number of times, logging a diagnostic code in memory and/or illuminating a diagnostic indicator.

17. A fault detection method for a motor vehicle charging system including a generator, a voltage regulator operatively coupled to said generator, an electrical component coupled to receive electrical current from said generator and a powertrain controller, said method comprising the steps of:

(a) if said charging system has an operational fault, providing a fault indicating signal from said voltage regulator to said powertrain controller indicative of said operational fault; and

(b) if said signal intermittently indicates said operational fault, providing a first charging system control signal from said powertrain controller to said voltage regulator to limit or suspend output of said generator.

18. A method as recited in claim 17, wherein said operational fault is an open circuit at an output of said generator.

19. A method as recited in claim 18, further comprising:

(d) providing a second charging system control signal from said powertrain controller to said voltage regulator to end said limiting or suspension of output of said generator; and

continuing to perform steps (a) through (c).

20. A method as recited in claim 19, wherein said fault-indicating signal, said first charging system control signal and said second charging system control signal are pulse-width modulated.