Model of Automotive Alternator Output Voltage with Rectifier and Voltage Regulator

The automotive alternator is a key component of the power supply system that provides power to on-board consumers and battery charging. The alternator's technical condition can be assessed by comparing the available output voltage and the voltage of a healthy alternator. The impact of a rectifier and a voltage regulator on the alternator voltage needs to be determined. The authors established that the connection of a rectifier distorts the appearance of the alternator parameters due to the Zener diodes used in it. The dependencies are linearized: further voltage increase is determined by the increases in alternator rotor rotation speed and excitation current. When connecting the voltage regulator, the required alternator voltage can be provided using the pulse-width modulation of the excitation winding current. The duty factor of the excitation winding current cycle reduces along with the increase of the rotor speed and increases proportionally to the alternator load current. The adequacy of the analytical model of the excitation winding current was confirmed in experiments with the dynamic change cycle of its variables. The developed analytical models describe the changes in the output voltage of a healthy alternator. These will be used to develop an imitation model that can accurately identify typical alternator faults, which can be used in the development of an onboard monitoring system for the automobile power supply system condition.