Dual voltage automotive electrical system with sub-resonant DC-DC converter
First Claim
1. A dual voltage automotive electrical system comprising in combination:
- a regulated source of DC defining a first system voltage;
a series resonant converter coupled to said first system voltage for supplying power to a load circuit at a regulated second system voltage that is lower than said first system voltage, said converter including a series resonant tank circuit inductively coupled to said load circuit and comprising series resonant tank elements defining a dominant resonant frequency of said tank circuit, a transistor bridge circuit including alternately activated bridge transistors for supplying current from the regulated source of DC to the tank circuit, and a gate drive circuit for activating said bridge transistors at a fixed and predetermined switching frequency below said dominant resonant frequency of said, tank circuit to provide a fixed and predetermined voltage conversion ratio between said first and second system voltages.
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Accused Products
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.
69 Citations
10 Claims
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1. A dual voltage automotive electrical system comprising in combination:
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a regulated source of DC defining a first system voltage; a series resonant converter coupled to said first system voltage for supplying power to a load circuit at a regulated second system voltage that is lower than said first system voltage, said converter including a series resonant tank circuit inductively coupled to said load circuit and comprising series resonant tank elements defining a dominant resonant frequency of said tank circuit, a transistor bridge circuit including alternately activated bridge transistors for supplying current from the regulated source of DC to the tank circuit, and a gate drive circuit for activating said bridge transistors at a fixed and predetermined switching frequency below said dominant resonant frequency of said, tank circuit to provide a fixed and predetermined voltage conversion ratio between said first and second system voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification