Automotive Alternator Synchronous Rectificaton Via Self-Sensing Method for Improved Vehicle Fuel Consumption

This paper presents the improvement in fuel consumption which results when the standard diode rectification scheme is compared to synchronous rectification for a standard automotive alternator. These two alternator rectification methods are compared when the alternator is installed in a ´small´ vehicle and run over a standard federal urban driving cycle. This paper shows that a more efficient rectification scheme will have a measurable impact on fuel consumption for a smaller vehicle. Accessory loads are more significant for small vehicles since these loads are a greater percentage of total power needed to propel the vehicle. A simple rotor position self-sensing method is used to determine when to switch the synchronous rectifiers and thereby emulate the operation of standard diodes.