Multiple-voltage power supply circuitry for motor vehicles

Details Multiple-voltage power supply circuitry for motor vehicles Multiple-voltage power supply circuitry for motor vehicles

2002-04-19

2004-04-06

Berhane, Adolf D. (Department: 2838)

Electrical transmission or interconnection systems

Vehicle mounted systems

Automobile

C307S038000

Reexamination Certificate

active

06717288

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to electrical power supply circuits, configured particularly for use on automobile vehicles.
More precisely, the present invention relates to an electrical power supply circuit of this type including a main direct voltage source powered by a rotating machine, and at least first and second auxiliary direct voltage sources powered from the main source.
BACKGROUND INFORMATION
The most conventional and the most widespread electrical circuit architecture at the moment is composed of an alternator driven by the engine of the vehicle and powering a distribution network at a single voltage, for example 14 volts, a 12 volt battery being installed on this network as a buffer.
Devices consuming electrical energy take power from this network through distribution boxes equipped with fuses that protect the electrical harness by isolating any electricity consumer device from the network if the device becomes defective, and particularly any device in which there is a short circuit.
In this type of architecture, devices consuming electrical energy can only dialog with each other through a multiplexed information network independent of the electrical energy distribution network.
The new situation created by the very fast growth in the number of electrical devices on automobile vehicles has recently made some automobile manufacturers consider increasing the voltage output by the electrical energy distribution circuit, for example increasing it to 42 volts instead of 14 volts.
However, since the construction of some electrical devices makes them inherently unsuitable for such an increase in the power supply voltage, and since a specific adaptation of these devices would lead to prohibitive costs, the planned evolution would initially require the use of at least two distribution networks, outputting electrical energy at two different voltages.
An example of the architecture of such an electrical energy supply circuit conform with this evolution is illustrated in FIG.
1
.
This type of circuit typically includes a rotating machine, such as an alternator A
0
, for example, outputting a voltage of 24 volts, this alternator AO being connected to a rectifier forming a main direct voltage source S
0
, for example, outputting a direct voltage V
0
equal to 42 volts.
A first auxiliary source S
z
outputting a direct voltage V
y
equal to 42 volts, is directly formed by the main source S0 buffered by a battery BAT
y
, for example, a 36 volt battery, this first auxiliary source supplying a first distribution network RD
y
.
A second auxiliary source S
z
outputting a direct voltage V
z
equal to 14 volts includes a direct/direct converter powered by the main source S
0
, the output of which is buffered by a battery BAT
z
, for example, a 12 volt battery, this second auxiliary source powering a second distribution network RD
z
.
Conventional solutions may be sufficient to satisfy some needs, and although these solutions use a single voltage as is the case for the classical solution, or at least two voltages as is the case of the architecture illustrated in
FIG. 1
, but a number of problems can arise with these solutions.
Firstly, the distribution of electrical energy using a voltage regulated circuit makes it necessary for each consumer device to includes its own direct-direct converter or be dimensioned to accept the available power supply voltage.
For example, since computers use electronic components that only accept low power supply voltages, usually 3 volts or 5 volts, all computers must be provided with direct-direct converters.
However, on the other hand, filament lamps must be sized to be supplied at 12 volts since they are too numerous and their value is too low to be fitted with such a converter. However, this size imposes the choice of relatively thin filaments, and consequently their life is not optimized.
Moreover, since these conventional solutions are designed such that a strong variation in the consumption of electrical energy will change the available voltage on the distribution network, the devices consuming electricity energy must themselves be designed to be able to resist these variations and therefore satisfy a severe specification that increases their manufacturing cost.
Furthermore, since conventional architectures are designed such that a short circuit in any one of the devices consuming electrical energy could cause an over current in the electrical harness and could destroy it if an appropriate protection is not provided, it is essential that the distribution network should be protected by fuses.
Finally, since they impose the use of capacitive input stages that naturally act as filters for high frequency signals, these architectures cannot be used as physical supports for carrier current information transmission systems.
It is an object of the present invention to provide an electrical energy supply circuit for an automobile vehicle, capable of solving at least one of the problems mentioned above due to its inherent principle.
SUMMARY
Consequently, the circuit according to the present invention includes a primary stage and at least first and second secondary modules forming the first and second auxiliary sources respectively, the primary stage including a primary alternating current generator supplied by the main source, a current loop that carries an alternating current produced by the primary generator, and at least first and second windings installed in series in the current loop and forming primary windings of the corresponding first and second transformers, and each secondary module including a corresponding transformer secondary winding and a current-voltage converter connected to this secondary winding, this current-voltage converter being configured to produce a direct output voltage from the alternating current circulating in the secondary winding.
Each secondary module may thus be sized such that its output voltage is adapted to the type of device powered by this module.
Therefore, devices consuming electrical energy are no longer sized under the constraint of an imposed power supply voltage, but they may be sized simply to satisfy the need to optimize its cost with regard to its function.
Moreover, to the extent that the network is configured for an alternating current, it does not filter high frequency signals, and therefore it may be used as a physical support for a carrier current information transmission system.
In an example embodiment of the present invention, the primary alternating current generator includes a primary alternating current regulator capable of controlling the amplitude of the current circulating in the current loop, and each secondary module includes a voltage regulator.
Due to the independence thus introduced between the global load on the circuit and the individual load of the different secondary modules, variations in the load on one such module do not affect the other modules, for which the output voltage is thus protected from any variation.
Moreover, to the extent that the current in the current loop, in other words in the harness that passes through the vehicle, is regulated in a primary stage, the risk that a short circuit in an electricity energy consumer device may cause a short circuit that would burn the harness is very much reduced.
For example, the primary alternating current generator may include a resonant circuit installed in series in the current loop and in which oscillations are maintained by pumping electrical charges taken at a given frequency on a charge storage circuit connected to the main direct voltage source and itself including one or several capacitors.
Consequently, the primary alternating current generator may include a transistor bridge and a driver circuit, the transistor bridge being connected to the charge storage circuit and to the resonant circuit to transfer electrical charges picked up from the charge storage circuit to the resonant circuit, and each pair of transistors in the transistor bridge adopting a cyclically variable conducting state, co

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