Dual voltage automotive electrical system with sub-resonant DC-DC converter

Abstract

An improved dual voltage automotive electrical system in which low voltage loads are powered by a series resonant DC-DC converter operated at a fixed switching frequency below the resonant frequency of its tank circuit. With this arrangement, the converter provides a fixed conversion ratio from the regulated upper system voltage, and operates with the beneficial attributes of zero current switching and inherent overload protection. In a first embodiment, a transformer inductively couples the converter tank circuit to the low voltage loads, providing full input/output galvanic isolation. In a second embodiment, the converter is configured so that a portion of the power supplied to the low voltage loads is directly coupled from the upper system voltage source, with the remaining portion being coupled through the converter. In either embodiment, the accuracy of the conversion ratio and its load current independence are enhanced by a compounding coil having a load current dependent inductance coupled to the tank circuit.

Dependencies are inferred from the claim text.