DE2458779A1 - AC GENERATOR - Google Patents

Description

R. 2 4 8 6

12/4/74 Chr / Sm

Attachment to

Patent and

Usage pattern auxiliary registration

ROBERT BOSCH GMBH, Stuttgart Alternator

The invention relates to an alternator according to the preamble of the main claim. Alternators for that Supply of a battery charger and other consumers in motor vehicles are in a very wide speed range operated. However, the generator output voltage should always be constant, this is generally done with the help of a voltage

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controller reached. How to get from the well-known generator characteristic can be seen, the achievable output current of a generator increases roughly in form with a constant output voltage of a horizontal parabola with increasing speed. The achievable output current increases in the higher speed range but only a little too, so the output current is limited. If you increase the number of turns per phase of the stator winding at a generator, the output current starts at a lower rotor speed, but it can only be achieve lower output currents in the upper speed range. One is therefore forced to make a compromise to the effect that that a generator is sufficient in the lower speed range Can deliver output current, but also has as large an output current as possible in the upper speed range. the Experience has shown that generators that meet the performance requirements in the lower speed range, in the upper Speed range work below the operating temperatures already reached in the lower speed range. This is an indication ensure that these generators are not fully utilized in the upper speed range.

Arrangements have already become known in which the stator winding a delta connection is switched to a star connection depending on the rotor speed. There are also orders became known, in which the individual windings of the stator from a star connection in a series connection be switched. These arrangements require a relatively high expenditure of switching means. Also join the Switching high voltage peaks on. Reach the voltage peaks Values that are a multiple of the nominal voltage of the generator. This can cause the well-known consequences such as winding shorts and short circuits to ground occur, repeated switching can even destroy the rectifier diodes.

The invention is concerned with possibilities, the performance and the efficiency of alternators in the upper speed range to be improved by a new type of circuit technology

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- In particular during the operation of the generator -, and has the characterizing features of the main claim. Through the The measures listed in the subclaims are advantageous developments and improvements of the measures specified in the main claim Generator possible.

The invention enables a better energy supply of Motor vehicles, the generator according to the invention has a higher efficiency than the generators commonly used up to now. With the same output power, a smaller "volume and Less weight is required than with the generators customary up to now, resulting in better installation options especially in motor vehicles.

That the various known solutions did not prevail is due to economic and technical reasons. The known solutions require a plurality of switching elements, which are partially or completely to the maximum Electricity must be dimensioned. During the switching process, the phase windings of the generator are separated from each other, which equates to a complete generator relief; but the magnetic energy accumulated in the runner cannot, at the moment can be reduced, as a result of which high voltages can be induced in the stator windings, which is the case above the described destruction of semiconductor elements. The invention avoids all of these disadvantages.

The generator according to the invention has a stand with a Three-phase winding. As the winding connections to the rectifier bridge are connected, the generator according to the invention is a three-phase system. Characteristic for this circuit is that with a highly utilized generator that works in a large speed range, in the upper speed range a better characteristic is achieved than with a conventional generator,

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which has stator windings connected in a triangle. The reason This is because the third harmonic of the voltage, which occurs at high speeds and high loads, has a third Generates harmonic current for which the delta connection represents a short-circuit winding. This current with the usual generators generates the additional copper losses, which result in a heating of the phase winding and in an increase in size express the winding resistance and thus lead to a reduction in performance to lead. When the invention. Generator can Third harmonic currents do not arise because the Phase windings are separated from one another by the rectifier arrangement for the currents of the third harmonic.

In a further advantageous embodiment of the generator according to the invention is in a very simple way the three-phase single-phase connection can be converted into a real star connection. The stator winding is in the lower speed range Connected in star, after opening the switching bridges of the switching device, the generator works in three-phase operation Further. Switching from star connection to three-phase single-phase connection and vice versa can be done in different ways Points of view happen, z. B. load current ·; speed, frequency or depending on the temperature or manually.

Switching from star connection to three-phase operation can also be carried out continuously according to further exemplary embodiments of the invention, so that a continuous one is obtained Transition from the characteristic curve of the star connection to the characteristic curve of the three-phase single-phase connection.

The means for switching can be mechanical contact bridges, but also controllable semiconductors, transducers, chokes, Resonant circuits or resistors with a positive temperature coefficient. All exemplary embodiments can be used with generators with slip rings or with generators without slip rings or with permanent magnet generators. · ·

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The following are embodiments of the invention by reference explained in more detail on the drawing.

Fig. 1 shows a first and a second embodiment of the generator according to the invention. A rectifier arrangement initially contains three plus load diodes 1 and three minus load diodes

2, which are connected in the usual way and are connected to the plus output terminal and the minus output terminal of the generator. Furthermore, the rectifier arrangement contains three excitation diodes 3 »A phase winding arrangement 4 is divided into three partial windings 4a, 4b, 4c which are electrically offset from one another 120. One end of each of these partial windings 4a, 4b, 4c is at the anode of a plus load diode 1, the cathode of a minus load diode 2 and the anode of an exciter diode 3 « ^f _{s contains} three minus load diodes 2 'and three excitation diodes 3'. The second ends of the partial windings 4a, 4b, 4c are each connected to the anode of one of these additional plus load diodes I ¹ , the cathode of an additional minus load diode 2 ^f and the anode of an additional exciter diode 3 '. In the exemplary embodiment shown, the generator according to the invention also has an excitation winding 5, which is connected on the one hand to the negative output terminal of the generator and, on the other hand, via a voltage regulator 6 to the cathodes of the excitation diodes

3, 3 'is connected. The series circuit of an ignition switch 7 and one leads from the cathodes of the excitation diodes 3, 3 ' Charge control lamp 8 to the positive output terminal of the generator. There is a series circuit across the two output terminals of the generator from a load 9 and a load switch 11 and a battery 10. The generator is as described so far is already functional and has all the essential advantages of the invention.

Another exemplary embodiment is also indicated in FIG. 1. A contact bridge 12a, 12b, 12c of a switching device 12 is connected to the second ends of the partial windings -4a _{s 4b, 4c of the phase winding arrangement 4.} The others

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Contacts of the contact bridges 12a, 12b, 12c are connected to one another. If the contact bridges 12a, 12b, 12c of the switching device 12 are closed, then the three-phase single-phase connection is established of the first embodiment is converted into a star connection.

The switchover device 12 can be switched over in several ways. In Fig. 1, the switch is with the help of a Power relay device 13 is shown. The current relay device IJ responds to the output current of the generator, i.e. the load current. When the generator in the star connection has an output current supplies, which it can also supply in the three-phase single-phase circuit at this speed, actuates the current relay device 13 the switching device 12, the switching bridges 12a, 12b, 12c are opened and the generator works instead of in the star connection in the three-phase single-phase circuit. The load current increases or the speed continues, the generator remains in the three-phase single-phase connection. However, if the speed and / or the load current decreases, the generator is switched back to the star connection switched. · ■

In Fig. 2 is a second embodiment of the invention Generator shown. The same parts are provided with the same reference symbols. The second embodiment differs differs from the first embodiment in that the switching device 12 has only two switching bridges 12a, 12b. The third switching bridge has been replaced by a simple line. It can be seen that the mode of action is the same as with the first Embodiment.

In Fig. 3a it is indicated how the switching bridges 12a, 12b and optionally 12c by an arrangement with controllable rectifiers 14 can be realized. Fig. 3b shows a Realization of the switching bridges 12a, 12b and possibly 12c by magnetic amplifier arrangements 15 · The impedance of the magnetic amplifier arrangement 15 is a function of the load current and the generator speed. The switching arrangements 12 in the Embodiments

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after Pig. 3a and 3b must be controlled from the outside.

In Fig. 4 circuit arrangements 12 are shown, which none Need external control. The switching arrangements 12 according to FIG. 4 enable a continuous characteristic curve. The circuit arrangement 12 according to FIG. 4a contains a throttle arrangement 16, whose impedance is a function of the generator speed. The embodiment of Fig. 4b shows a switching device 12, the resonant circuit arrangements with chokes 17 and capacitors 18; is the impedance of the resonant circuit arrangements 17, 18 also a function of the generator speed. In Fig. 4c an embodiment is indicated in which the changeover device 12 resistors 19 with a positive temperature coefficient having; the resistance value of the resistor 19 is a function of the temperature, the resistor 19 is expediently placed inside the generator.

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Claims (10)

/4.58779 - 8 - R. ■ £ 4 ξ> Claims 1. Alternator, especially alternator for Motor vehicles', with a phase winding arrangement electrically offset from one another by 120, preferably in the stator, with one of the phase winding arrangement downstream, Rectifier arrangement containing load plus diodes, minus load diodes and exciter diodes and with an exciter winding arrangement, preferably in the rotor, characterized in that the phase winding arrangement (4) contains a partial winding (4a, 4b, 4c) with separately lead-out winding ends for each phase and that each of the partial windings (4a, 4b, 4c) has its own full-wave rectifier bridge with plus load diodes (1, 1 ') and minus load diodes (2, 2 ¹ ) and its own set of excitation diodes (3, 3' ) is connected downstream. 2. AC generator according to claim 1, characterized in that one winding ends of the partial windings (4a, 4b, 4c) ' can be connected to one another by means of a switching device (12) are. 3. AC generator according to claim 2, characterized in that the switching device (12) for each winding end one Contains switching bridge (12a, 12b, 12c). -9 - ■ 609825/0153 4. AC generator according to claim 2, characterized in that the switching device (12) has two switching bridges
(12a, 12b), one contact of which is connected to one winding end (4a, 4b) and the other contacts of which are connected to the third winding end (4c). 5. AC generator according to one of claims 2 to 4, characterized characterized in that the Umsehaltvorrichtung (12) means a current relay device (13) can be controlled by the generator output current. 6. AC generator according to one of claims 2 to 5, characterized characterized in that the switching bridges (12a, 12b; 12c) are realized by thyristors (14) (Fig. 3a). 7. AC generator according to one of claims 2 to 5, characterized in that the switching bridges (12a, 12b; 12c) are realized by magnetic amplifier arrangements (15)
(Fig. 3b). 8. AC generator according to one of claims 2 to 5, characterized in that the switching bridges (12a, 12b, 12c) by inductive resistors, preferably by chokes
(16), are realized (Fig. 4a). - 10 - 609825/01 53 9. AC generator according to one of claims 2 to 5j, characterized in that the switching bridges (12a, 12b; 12c) are realized _{by resonant circuit arrangements (17 3 l8)}
(Fig. 4b). 10. AC generator according to one of claims 2 to 5 _S, characterized in that the switching bridges (12a, 12b, 12c) are realized by resistors (19) with a temperature-dependent resistance value (Pig. ¹ Ic). 609825/0153