Electrical transmission or interconnection systems – Vehicle mounted systems – Automobile
Patent
1998-06-01
2000-03-28
Paladini, Albert W.
Electrical transmission or interconnection systems
Vehicle mounted systems
Automobile
318154, 318493, B60L 1102
Patent
active
060435674
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to a vehicle electrical system with a generator that has an exciter circuit which is influenced by a voltage controller wherein a first voltage level and a second, higher voltage level are provided.
In conventional electrical systems, electrical energy is usually generated with the aid of a three-phase generator. The three-phase generator voltage is converted by a diode rectifier to the required direct voltage for the vehicle electrical system. Circuits using rectifier diodes, Schottky diodes or Z-diodes are known for converting three-phase voltage to the required direct voltage. Moreover, combinations of various diode designs in a rectifier are conceivable as well. Parallel-connected diodes for increasing the maximum current can also be used as needed.
A voltage controller that is connected to the generator exciting circuit is used to adjust the amplitude for the rectifier output voltage to the value necessary for supplying voltage to the vehicle electrical system.
A vehicle electrical system having a higher medium voltage as compared to the battery voltage, as well as a high voltage, is known from the DE 40 41 220 A1, from which the invention starts. A joint medium voltage bus bar is provided, for which a stabilized voltage is maintained by a voltage-controlled converter arrangement. The system has the disadvantage that the battery is charged by a generator to the lowest voltage level, which results in higher losses in the generator, as compared to a generator that generates a higher voltage. The layout for a vehicle electrical system still widely used is based on the concept of adjusting to the generator output voltage. This concept has the disadvantage that all voltage drops occurring between generator and battery are not taken into account. The rated 12V voltage is present at the battery and at the majority of the electrical consumers or devices which consume electrical energy.
An electrical system for a satellite, having a battery voltage of 64-84V and a higher bus bar voltage of 120V is known from an article contributed to a conference by the Aerospace Power, San Diego, Aug. 3-7, 1992,Vol. 1, IEEE, pages 1.73-1.78, XP000366011, by J. P. Noon et al., `Design of a Multi-module, Multi-phase Battery Charger for the NASA EOS Space Platform Testbed.` Solar panels feed energy into the bus and charge up the battery via several parallel-connected chopper stages. After dark, the bus bar voltage is obtained in a reverse operation from the battery voltage.
If particularly powerful electrical consumers are used, the low voltage of the vehicle electrical system is problematic because of the high current intensities. For example, the resulting high losses must be taken into account for the cable cross section rating. If semiconductor elements are additionally used in the powerful consumers, then these must also be dimensioned for the high current levels, which results in increased costs.
SUMMARY OF THE INVENTION
It is the object of the invention to solve the problem of providing an additional, higher direct voltage level U2 with a constant voltage for powerful electrical consumers in addition to the lower conventional electrical system voltage U1 which may be rated 12V.
In accordance with the invention, the problems associated with the prior art are solved by realizing the first lower voltage level through a parallel connection of several chopper stages and wherein the second, higher voltage level is present at the output of the generator and the voltage controller adjusts the first, lower voltage level.
When using power-electronics circuits, such as unidirectional or bidirectional DC/DC converters, it is particularly important to observe the regulations applicable for motor vehicles with respect to the electromagnetic compatibility of these circuits.
If a second, higher direct voltage level U2 for powerful consumers is introduced in the motor vehicle in addition to the conventional voltage level U1 of rated 12V, and if the two nets are connected with the aid of a chopper, the
REFERENCES:
patent: 4143280 (1979-03-01), Kuehn et al.
patent: 4191914 (1980-03-01), Lecluse
patent: 4264846 (1981-04-01), Sauer et al.
patent: 5642023 (1997-06-01), Journey
Noon et al, "Design of a Multi-Module, Multi-Phase Battery Charge for the NASA EOS Space Platform Testbed", IECEC-92, San Diego, CA, Aug. 3-7, 1992, vol. 1, pp. 1.74-1.78.
Uhler Rainer
Zimmer Markus
Daimler-Benz Aktiengesellschaft
Paladini Albert W.
Spencer George H.
Voorhees Catherine M.
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