Abstract: A system and method for charging an auxiliary battery (107) that drives an auxiliary load (109) includes a regulator (111', 223) coupled to an auxiliary battery (107). The regulator (111', 223) provides a charge current (121') that is variable dependent on a parameter of a control signal (203). Preferably, the parameter is an amplitude. A switch (113') provides a coupling and a decoupling between the auxiliary battery (107) and the auxiliary load (109). A control device (115') decouples the auxiliary battery (107) from the auxiliary load (109) via the switch (113'), and then provides the control signal (203) to the regulator (111', 223). By effecting this action, the regulator (111', 223) provides the variable charge current (121') to the auxiliary battery (107) dependent on the amplitude of the control signal (203).

Abstract: Semiconductor device protection circuit (10) provides increased power dissipation (current) limits for FET (11) when lower FET temperatures exist. The FET drain to source voltage (V.sub.DS) is monitored to provide a current sense signal (54). When the current sense signal exceeds a predetermined reference limit signal (V.sub.REF,55), a control circuit (23, 32) reduces current (power dissipation) in the FET. Circuitry (24) provides the reference limit signal (V.sub.REF) with a predetermined temperature variation as a function of the sensed temperature of the FET whereby for low device temperatures higher power dissipation (current) limits for the FET are provided. An additional control circuit (21, 30) provides short circuit overcurrent protection by reducing current in the FET when sensed FET current exceeds a predetermined limit. A delay circuit (39) inhibits operation of at least the control circuit (20, 32) until a predetermined time (t.sub.1) after the FET is turned on.

Abstract: The circuit utilizes combinational logic and latching circuits to prevent damage to the regulator or to the battery of an automotive ignition system due to a serious fault such as the ignition being turned "on" but the engine/alternator not rotating. A fixed duty cycle control signal is added to the control signal for the field excitation current only when a serious fault is detected, thus limiting battery drain and excessive temperature in the regulator module but not shutting the whole system down. The system thus provides the desirable "limp-home" capability.

Abstract: The protection system includes an over-temperature warning lamp in addition to the usual charge indicator lamp. Both lamps light at ignition as a test, then both go out. If the alternator should fail, both lamps again light. If the alternator overheats, only the warning lamp is lighted and current to the field coil is removed.

Abstract: A charging system for amplifying AC output voltages induced in at least one stator winding of an alternator by residual magnetism from a low carbon steel rotor to self-excite the charging system by means of the residual magnetism at low engine RPM. An electronic voltage regulator is responsive to small AC output voltages from the stator winding, even below voltage levels required to forward bias a silicon semiconductor junction, to fully energize the field winding of the alternator. Since the voltage regulator is responsive to alternator signal developed at low engine RPM, the regulator can also be used as a sensor to indicate an operative engine condition, such as start up.

Abstract: A regulated automotive alternator battery charging system is disclosed. The system comprises an engine-powered alternator which provides a rectified alternator output signal for charging an automobile battery in accordance with an alternator field coil excitation signal provided by a voltage regulator which senses the battery voltage and alters the field coil excitation in response thereto to maintain the battery in a charged condition. The voltage regulator comprises an oscillator for developing a constant frequency signal which is independent of engine speed and battery load. The regulator includes circuitry for varying the duty cycle of this constant frequency signal in accordance with the sensed magnitude of battery voltage, and the constant frequency but variable duty cycle signal is utilized to provide field coil excitation for the alternator wherein the system maintains the battery voltage at a substantially constant magnitude.

Abstract: Field coil current of an alternator is controlled in response to temperature as well as to battery voltage, thus allowing maximum safe output power at any ambient temperature. A monostable circuit is utilized for reducing the maximum duty cycle of the field excitation driver in response to a sensed temperature without increasing power dissipation in the regulator.

Abstract: 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.

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.

Abstract: A fault indicating circuit for an automobile alternator battery charging system is disclosed. The charging system comprises an alternator providing a rectified battery charging signal in response to alternator field coil excitation which is controlled by a voltage regulator that senses battery voltage. The fault indicating circuit comprises a low voltage detector circuit which provides constant DC excitation for an indicator lamp in response to low alternator output voltage and a high voltage detector circuit which provides intermittent excitation for the lamp in response to an excessively high alternator output voltage, the lamp being maintained in a de-energized state in response to the normal alternator output voltage.

Abstract: 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.

Abstract: An automotive battery charging system having a voltage regulator circuit with an improved feedback network for controlling the duty cycle and frequency of current in the field coil of the alternator. The feedback network includes a filtering circuit to minimize the effect of voltage spikes and ripple on feedback current. The filtering circuit is in the form of a variety of networks for clamping filtering and regulating.