Can an AC (alternating current) electrical system replace the present DC system in the automobile? An investigative feasibility study. I. System architecture

In the aerospace industry, the 400-Hz AC system replaced the DC system, and the latest trend in aerospace industry involves a combination of mixed AC and DC electrical system applications. With more and more equipment in the newer automobiles and a corresponding increase in power requirement, it is anticipated that in the not too distant future higher voltage and/or some different architecture will be necessary in order to have an efficient electrical system. The question addressed in this paper is whether an alternative single- or three-phase AC electrical distribution and load system could replace the present DC system and, if so, what kind of architecture should be used. In this paper, first the electrical system architecture is described. Other issues discussed include the comparison of relative cost and size issues arising due to: (1) additional DC-AC power electronic converter hardware; (2) changes in the wiring system; and (3) the use of induction motors which can adequately handle the motor loads without any added power and/or control electronics at certain chosen frequency(ies). It is shown that for a three-phase system there will be a net total saving. The benefits of the AC system are not just based on cost, but on reliability and robustness as well. It seems that a replacement of the present electrical system with a three-phase AC system could be a reasonable step toward alternative electrical system selections.