Electricity: single generator systems – With physical starting and/or stopping of the generator
Patent
1998-06-22
1999-12-07
LaBalle, Clayton
Electricity: single generator systems
With physical starting and/or stopping of the generator
322 29, 307 106, 290 31, 290 46, H02P 300, H02H 706, B60R 2200, F02N 1104
Patent
active
059989769
DESCRIPTION:
BRIEF SUMMARY
The invention is based on an arrangement for voltage supply as generically defined by the preamble to the main claim. Such an arrangement includes an electrical machine which can be operated as a generator or as a starter and is drivable by an internal combustion engine and can be connected to a battery via an intermediate voltage circuit, which includes at least one voltage converter and at least one changer.
PRIOR ART
Generating electrical energy, especially for an on-board electrical system of a motor vehicle, is typically done with a rotary current generator, whose output voltage is regulated by a voltage regulator. As generators, electrical machines that also act as starters in the starting mode can be used. One arrangement for voltage supply in an on-board electrical system of a motor vehicle in which this kind of starter/generator is employed is known for instance from German Published, Non-Examined Patent Application DE-OS 37 43 317. Here the starter/generator is connected to the battery via an intermediate voltage circuit, which includes changers and voltage converters. The starter/generator is designed such that in the generator mode it generates a voltage that is substantially higher than the on-board electrical system voltage. The on-board electrical system voltage is generated from this substantially higher voltage by using a voltage converter. In the starter mode, the voltage converter generates the higher voltage for the starter from the on-board electrical system voltage of the battery.
ADVANTAGES OF THE INVENTION
The arrangement for voltage regulation according to the invention, having the characteristics of claim 1 has the advantage over the known embodiment that the voltage at the electrical machine that can be operated as a starter/generator is optimally adaptable to the needs prevailing in starting and to those prevailing during normal generator operation. These voltage requirements during starting and during normal operation are such that in starting, when the electrical machine is operated as a starter that is intended to bring the engine to a relatively low rpm (starting rpm), a low voltage suffices to generate a sufficiently high moment, while during normal operation at higher rpm, a higher voltage leads to a better voltage supply for the on-board electrical system. The fact that only a low voltage is needed during starting is especially advantageous, because precisely in starting a lesser power or voltage can be output by the battery.
This advantage is attained by bypassing the voltage converter during the starting phase and supplying the changer, which is connected to the starter/generator, with the lower on-board electrical system or battery voltage, while in the generator mode the voltage converter is activated and as a result the changer is operated with the high voltage.
Further advantages of the invention are attained by the provisions recited in the dependent claims. It is especially advantageous that in the starting mode and in normal operation the voltage can be adapted within certain limits to requirements; suitable triggering means for the changers or partial bypassing of the voltage converter make it possible to generate different voltages. Since in the generator mode, for the sake of good efficiency, high voltages are desired, it may be advantageous to design the generator such that it achieves voltages that are far higher than the voltage of the on-board electrical system. To allow maximum power in operation of the machine as a generator, up to the maximum rpm, it may be helpful, in the case of drives that have a field attenuation region, to vary the transition to field attenuation by lessening or reducing the bypassing of the converter.
It is not absolutely necessary to use a bidirectional voltage converter as the voltage converter, because voltage conversion in only one direction is needed during generator operation. The design of the system need not take extreme cold starting values into account, since the starting power does not necessarily have to be trans
REFERENCES:
patent: 4883973 (1989-11-01), Lakey et al.
patent: 5175439 (1992-12-01), Harer et al.
patent: 5929537 (1999-07-01), Glennon
LaBalle Clayton
Medley Peter
Robert & Bosch GmbH
Striker Michael J.
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