Electricity: single generator systems – Automatic control of generator or driving means – Speed or frequency of generator
Reexamination Certificate
1999-03-26
2001-10-09
Enad, Elvin (Department: 2834)
Electricity: single generator systems
Automatic control of generator or driving means
Speed or frequency of generator
C322S028000, C322S059000
Reexamination Certificate
active
06300746
ABSTRACT:
The invention is based on a method for regulating a generator, in particular a three-phase generator that can be driven by an internal combustion engine in a motor vehicle, as generically defined by the preamble to the main claim.
PRIOR ART
To generate the electrical energy needed in the motor vehicle, claw pole generators are typically used today. These claw pole generators are three-phase generators, whose output current is rectified with the aid of a diode bridge and is used both for supplying the electrical consumers of the vehicle and for charging the battery.
A three-phase generator of this kind includes a field coil, through which field current flows. The field current is regulated with the aid of a voltage regulator in such a way that the output voltage of the generator is approximately constant, regardless of the rpm of the generator. In the stator windings of the generator, it is known that an rpm-dependent voltage is induced that drives a current through the rectifier bridge. The output current of the generator together with the generator voltage produces the power furnished by the generator. In
FIG. 1
, the generator power P(kW) of a claw pole generator, at UGN=14 V, it plotted over the generator rpm n(1/min) at different output voltages Ub. The maximum output power as a function of the generator rpm extends along the tangent line T. It is along this line that the utilization C=P
of the generator is highest. The power per rpm is accordingly at a maximum on the tangent line T.
From the Bosch publication entitled “Elektrische Motorausrüstung” [Electric Motor Equipment] by G. Henneberger, published by Vieweg-Verlag, p. 55, it is known that generators in operation with free voltage (free generator mode) produce higher output capacities at a corresponding terminal resistance than in the mode with regulation to a constant 14 V output voltage. Yet a free generator mode is not readily possible, since generator output voltages could arise then that could considerably impair the on-board electrical consumers.
ADVANTAGES OF THE INVENTION
The method of the invention for regulating a generator as defined by the characteristics of claim
1
has the advantage that the power range of the generator is better exploited.
These advantages are attained in that the exciter current of the generator is not regulated in a lower generator rpm range, so that the generator then operates in the free mode. Above a predeterminable rpm, the field current is regulated, so that excessively high generator voltages do not result.
Further advantages of the invention are attained by the characteristics recited in the dependent claims. It is especially advantageous that the rpm beginning at which the regulation of the exciter voltage is performed is an rpm at which the generator voltage is approximately equivalent to the on-board electrical voltage. This assures that regulation of the field current begins before excessively high generator voltages become possible. Since in the free generator mode at low rpm operation along the tangent line is possible, a maximum rate of increase of the power as a function of the available generator rpm can be attained. By using direct voltage converters that convert the output voltage of the generator to on-board electrical voltage, it is possible to adapt the generator to predeterminable conditions. If direct voltage converters which can function as both step-up converters and step-down converters are used, a further increase in generator power as a function of the available generator rpm is possible over a wide generator rpm range.
REFERENCES:
patent: 5061889 (1991-10-01), Iwatani et al.
patent: 5880577 (1999-03-01), Aoyama et al.
patent: 5998976 (1999-12-01), Steffan
patent: 6037753 (2000-03-01), Uematsu et al.
patent: 6060866 (2000-05-01), Sada et al.
“Elektrische Motorausruestung”, by G. Henneberger, published by Vieweg-Verlag, pp. 54-57.
Dittmer Bernd
Luz Oliver
Mueller Wolfgang
Schoettle Richard
Enad Elvin
Medley Peter
Robert & Bosch GmbH
Striker Michael J.
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