Abstract: A voltage regulation system for an automobile comprises a voltage regulator and a powertrain control module. The powertrain control module has a quartz crystal as its time base, while the voltage regulator has a less-expensive, though more environmentally robust resistive-capacitive (RC) oscillator. The voltage regulator and powertrain control module communicate between one another using pulse-width modulation. Drift in the frequency of the RC oscillator in the voltage regulator is recognized through the powertrain control module's measurement of the frequency of the signal sent by the voltage regulator. The powertrain control module adjusts the frequency of the signal it sends to the voltage regulator, assuring that the drift in frequency of the RC oscillator does not inhibit accurate PWM communications between the two devices.

Abstract: An enhanced charging system for a motor vehicle includes an alternator, a voltage regulator, and an engine controller. The voltage regulator and engine controller are connected by two circuits. One of the circuits provides the engine controller with a measure of the torque about to be applied to the engine by the alternator. The other circuit allows the engine controller to command the target voltage at which the voltage regulator is to control the alternator. The engine controller determines the target voltage based on intake air temperature, a measure of the temperature of the air at the intake of the engine. The engine controller then modifies the target voltage based on (1) whether the throttle of the engine is near wide-open-throttle; (2) whether the brakes of the vehicle are applied; and (3) whether the alternator is about to apply an increased torque to the engine.