Motorola Corporation

Robert W Mortonson

Kirk A Sievers

An in situ self-diagnostic automotive alternator battery charging system is disclosed. Included are: a battery; voltage regulator sensing battery voltage and generating an excitation signal; and an alternator driven by a vehicle engine provide a rectified electrical signal to charge the battery in response to the excitation signal. Electronic circuit status detectors, variously coupled to the battery, voltage regulator and alternator, maintain a first logic state when a corresponding signal characteristic is within a predetermined range and a second logic state when the corresponding characteristic is outside the predetermined range. Combinatorial logic means respond to a logic state sequence from the detectors to identify predetermined sequences of the logic states resulting in the identification of faults in the charging system. The logic means also provides a warning to the operator of detection of a fault and a display of the location of the fault as occurring in one of the major components of the charging system.

Fault detection and diagnostic system for automotive battery charging

A detector monitoring the voltage ripple in the rectified electrical output signal of an alternator in a multiphase alternator battery charging system is disclosed. A circuit monitors the undulating alternator output signal and produces a signal level in response. To correct the detector operation for various magnetic phenomena present in the alternator, a first circuit measures the rotational speed of the rotor and produces a proportional signal. A second circuit determines the excitation current supplied to the field coil. The measurement and determination are separately weighted and combined to form a corrected comparison threshold value. A variable threshold circuit combines the signal proportional to the rotational speed of the rotor and the determined field coil excitation current to produce a combined signal level. Comparison means compare the signal level from the monitored alternator output signal with the combined signal level and produce an output signal level indicative of the detection of a voltage ripple in excess of the combined signal level. The output signal is corrected for the effects of significant alternator performance characteristics.

Ripple detector for automotive alternator battery charging systems

A detector monitoring the operational status of the field coil circuit in a multiphase alternator and voltage regulator battery charging system is disclosed. Circuit means monitor a first signal at a first terminal of the field coil circuit. Means generate sampling intervals on a repetitive basis. Circuit means interrupt the excitation signal supplied to the field coil by the voltage regulator during the sampling intervals. A second signal is measured during sampling intervals at a second terminal of the field coil circuit. Comparator means compare the first and second signals and produce an output signal when the comparison varies from a predetermined value.

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Addison, IL, United States of America

Robert W Mortonson