A system for charging of dual voltage level batteries in automotive applications

The aim of the paper is to present a new system for charging of dual voltage level batteries in automotive applications. The proposed system is built as an arrangement of in induction machine and a bi-directional converter. In a near future, two batteries with different voltages will coexiste on the automotive electrical system board. A first one for power hungry devices, start-up, alternator, auxiliary motors and a second with 14 V for digital, calculation or radio circuits. The two batteries are recharged using a single alternator. An initial solution for this consists of using two converters. Firstly, the alternator recharges the highest voltage battery using a rectifier or a switching mode converter. Then the high level battery recharges the lower voltage battery, through a separate DC/DC step-down shopper. Compare to this traditional solution, a more economic one would be a DC/DC chopper by recharging the two batteries through a single switching mode converter. This article studies the resulting device and simulates its functioning in the case of an induction generator. Only simulations results are shown, practical results will be published in a next paper.