| In this paper there are presented a few aspects regarding the operation of the direct current power supply system of cars. The operation of the electronic voltage con-troller is specially approached. Theoretical aspects of the problem are presented. In the second part of the paper there are presented a series of experimental determinations car-ried out on a modern stand. The results have been con-firmed by measurements with a car. In order to analyze the rectifier defects there have been viewed the output voltage waveforms for five situations of defect of the diodes. In or-der to analyze the voltage control, there have been obtained the waveforms of the excitation current for three particular situations. In the last part of the paper there are presented the conclusions obtained following the researches. It is em-phasized that: damaging one or more diodes of the rectifier can be identified by viewing, by means of an oscilloscope, the waveform of the output voltage of the alternator; when one of all the diodes is functional, the waveform is symmet-rical, waved and with small variations; for the same number of damaged diodes, the distortion degree of the voltage also depends on their position in the rectifying bridge (e. g. the distortion is higher when two positive diodes are damaged than in case when a positive diode and a negative one are damaged); an existing fault situation can be identified by viewing the output voltage of the alternator. |
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