Electricity: single generator systems – Automatic control of generator or driving means – Plural conditions
Patent
1994-12-08
1996-06-04
Stephan, Steven L.
Electricity: single generator systems
Automatic control of generator or driving means
Plural conditions
322 28, 322 59, H02J 714
Patent
active
055236723
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is directed to a voltage regulator for regulating the output voltage of an alternator driven by an internal combustion engine as set forth in the generic part of the main claim.
Currently, three-phase alternators are preferably used for supplying the electrical consumers of a motor vehicle. These alternators generate an AC voltage or alternating current which is rectified in a rectifier arrangement connected downstream of the alternator and is used to supply consumers and charge the battery. Since the output voltage of the three-phase alternator substantially depends upon the rate of rotation of the alternator, a voltage regulator must be used to achieve the desired constant output voltage.
In separately excited alternators, the voltage regulator influences the alternator exciter current. The exciter current switches on and off continuously by means of a transistor. The given exciter current duty cycle depends on the magnitude of the load on the alternator and on the speed of the internal combustion engine and accordingly on the speed of the alternator.
An alternator/voltage regulator system of this kind is known, for example, from U.S. Pat. No. 4,424,477. In this known system, the voltage of the battery of the vehicle is measured and tested to determine whether or not this voltage lies below a set value. If it does, the idling speed of the internal combustion engine and that of the alternator is increased so as to increase the output power of the alternator. This known voltage regulator has the disadvantage that the battery voltage must be measured additionally to detect a poor charging state.
ADVANTAGES OF THE INVENTION
The voltage regulator according to the invention for regulating the output voltage of an alternator which is driven by an internal combustion engine has the advantage over the prior art that the exciter voltage duty cycle is measured directly and is used to form a suitable digital signal so that additional steps required as a result of a poor charge state or intensive loading of the alternator can be carried out in a simple manner.
In an advantageous manner, a signal can be tapped directly via an additional connection at the regulator so that it may be determined on the basis of the level of this signal whether or not to carry out additional steps, e.g., an increase in the idling speed.
DRAWING
An embodiment example of the invention is shown in the drawing and explained in more detail in the following description. FIG. 1 shows a conventional alternator/regulator system of a motor vehicle which is supplemented by the circuit according to the invention. This circuit according to the invention is shown in more detail in FIG. 2.
DESCRIPTION OF THE EMBODIMENT
A three-phase alternator 10 supplying an onboard power supply system, designated by 11, is shown schematically in FIG. 1. The alternator output voltage UB+ is regulated by a voltage regulator 12. The connection terminals in an alternator voltage system of this kind are conventionally designated by D-, DF, D+ and B+.
The alternator 10 has an exciter winding 14 in addition to stator windings 13a, 13b, 13c. The drawing also shows rectifier bridges 15a, 15b and 16 for rectifying the alternator output current or exciter current.
Only the following elements of the motor vehicle power supply system are shown in the drawing: charge level indicator light 15, terminal KL.15 which is connected with the ignition switch 16, a switch 17, a consumer 18, and battery 19 to which the individual consumers are connected.
The parts of the voltage regulator essential to an understanding of the invention are a switching element, e.g., a switching transistor 20 with a parallel-connected protective diode 21, a freewheel diode 22, and a controller 23 driving the transistor 20.
The exciter winding 14 between connections D+ and DF and the transistor 20 between DF and D- form a series connection. The current flow IE through the exciter winding 14 is controlled by opening and closing the switching path of the transistor 20. The duty c
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Kohl Walter
Meyer Friedhelm
Mittag Rainer
Schramm Guenter
Ponomarenko Nicholas
Robert & Bosch GmbH
Stephan Steven L.
Striker Michael J.
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