Stator fault detector for automotive alternator battery charging systems

• US 4,348,629 A
• Filed: 05/22/1980
• Issued: 09/07/1982
• Est. Priority Date: 05/22/1980
• Status: Expired due to Term

• Current Assignee: PEI 1991 Acquisition Incorporated
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Sievers, Kirk A.
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US06/152,224
• Time in Patent Office: 838 Days
• Field of Search: 322/28, 322/58, 322/99, 324/158 MG, 361/20, 361/21, 320/64, 320/68
• US Class Current: 322/99
• CPC Class Codes: G01R 31/007 using microprocessors or computers
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• 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
• CPC Class Codes: Y10S 320/13 Fault detection

Abstract

A detector monitoring the function of the stator and rectifying diodes in a multiphase alternator battery charging system is disclosed. A circuit combines individual phase signals from the alternator to form an artificial neutral at which a normally symmetric wave signal is present. A first comparison means detects deviations in the normally symmetric wave signal greater in value than a first threshold voltage level. A second comparison means detects deviations in the normally symmetric wave signal lesser than a second threshold voltage level. Means coupled to the first and second comparators produce an output signal whenever the normally symmetric wave signal deviates above the first threshold voltage level or below the second threshold voltage level. The detection of assymmetry in the normally symmetric wave signal indicates a fault in the stator or rectifying diodes of the alternator.

Claims

1. In a multiphase alternator battery charging system, said alternator producing a rectified electrical signal for charging said battery, a detector monitoring the function of the stator and rectifying diodes of said alternator comprising:

means coupled between said stator and said rectifying diodes, combining the individual phase signals of said alternator to produce a normally symmetric wave signal representative of the proper performance of said stator and diodes in said alternator;

first and second comparison means coupled to said combining means, said first comparison means detecting deviations in said normally symmetric wave signal greater in magnitude than a first threshold value, and said second comparison means detecting deviations in said normally symmetric wave signal lesser in magnitude than a second threshold value; and

means producing an output signal whenever said normally symmetric wave signal deviates above said first threshold value or below said second threshold value.

2. The detector of claim 1 wherein said combining means includes a common junction establishing an artificial neutral for said normally symmetric wave signal.

3. The detector of claim 2 wherein the signal at said common junction of said combining means is supplied to said first and second comparison means.

4. The detector of claim 3 further including voltage reference means having means to monitor said rectified electrical signal supplied by the alternator to establish said first and second threshold values at voltage values directly proportional to said monitored rectified electrical signal.

5. The detector of claim 4 further including an isolating transistor and wherein said voltage reference means is powered by said rectified electrical signal through (an) said isolating transistor preventing substantial current drain when said charging system is not operative.

6. The detector of claim 5 wherein said voltage reference means includes variable resistor means to separately adjust said first and second threshold values.

7. The method of detecting the operational status of the stator and rectifying diodes in a multiphase alternator battery charging system comprising the steps of:

combining phase signals derived from points between said stator and said rectifying diodes of said alternator producing a normally symmetric wave signal representative of the proper performance of said stator and said rectifying diodes in said alternator;

providing first and second voltage threshold values where the first threshold value is greater than the second;

comparing said normally symmetric wave signal separately with said first and second voltage threshold values; and

generating an output signal when said normally symmetric wave signal deviates above said first threshold value or below said second threshold value.