JPS61173700A - Exciter of self-excited ac generator - Google Patents

Abstract

PURPOSE:To self-establish a voltage at operation starting time with a simple structure without separately providing an exclusive DC power source by utilizing the remaining voltage of a generator as the initial exciting power source of an exciter of a self-excited AC generator. CONSTITUTION:An AC generator 1 is rotated by a driver 3. At this time, a thyristor 8 is impossible to control, but a light current is flowed through a generator W-phase, a normal-closed contact 4b, a regulating resistor 17, a reverse current blocking diode 18, a field winding 10, a generator U-phase during a period that the W-phase is higher than U-phase by the remaining voltage of the generator 1 in the example as shown, and the generator starts rising. Thus, the current further increases. The field current is increased while smoothing by the operation of the inductance of the winding 10 and a flywheel diode 9. An automatic voltage regulator starts controlling to self-establish the voltage, thereby starting the operation by an automatic voltage regulator.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an excitation device for a self-excited alternating current generator, and particularly to an improved means for establishing voltage at the start of operation.

(Prior Art) Most automatic voltage regulators (AVRs) for self-excited alternating current generators have recently been made into semiconductors, and among them, those based on a shunt-winding thyristor phase control system are the mainstream.

By the way, the automatic voltage regulator using the shunt-winding thyristor phase control method uses the output voltage of the alternator as the excitation power source, but at the start of operation, the automatic voltage regulator is still unable to control because the output voltage is small. Therefore, a separately excited initial excitation circuit is required that supplies initial excitation current from a separately prepared DC power source (for example, a battery power source with a charger).

FIG. 4 shows an example of an initial excitation circuit using a conventional separately excited DC power supply, and in this example, the automatic voltage regulator uses a single-phase half-wave rectification system among the thyristor phase control systems. In Fig. 4, 1 is a three-phase alternating current generator;
The generator 1 is coupled to a drive machine 3 such as an engine via a coupling device 2, and the generator 1 is rotationally driven by the drive machine 3. The line voltage between, for example, the W phase and the U phase of the output bus lines U phase, ■ phase, and W phase of the generator 1 is input to the voltage detection relay 4, and when the above line voltage reaches a predetermined value, the relay 4 is activated, opening the normally closed contact 4b in the initial excitation circuit 1, which will be described later.

Reference numeral 5 designates a control circuit for an automatic voltage regulator, into which, for example, the line voltage between the W phase and the U phase is input, and this voltage and the voltage setting device 6
is compared with the set voltage of AC generator 1, and the deviation signal is sent to AC generator 1.
The terminal type synchronizes with the phase of the wind and converts it into a phase-controlled dart pulse. 7 is a rectifier circuit consisting of a thyristor 8 and a flywheel diode 9. The f-) nolus output from the control circuit 5 is applied to the dart electrode of the thyristor 8 to control the conduction angle of the thyristor 8, and the half-wave rectified voltage is supplied to the field winding 10. be done.

11 is an initial excitation circuit; a DC power supply 12 for initial excitation;
It is composed of an initial excitation switch 13, a normally closed contact 4b of the voltage detection relay 4, an initial excitation current adjustment resistor 14, a backflow prevention diode 15, and the like.

To explain the action of the excitation device shown in FIG. 4, when the AC generator 1 is rotated by the drive machine 3 and the excitation switch 13 is closed when the rotation starts, the DC current from the DC power supply 12 for initial excitation is generated. is the normally closed contact 4b, and the initial excitation current adjustment resistor 14
The current flows through the backflow prevention diode 15 to the field winding 10, and excites the field winding 10 of the alternator. As a result, current flows through the armature winding of the generator 1, and its output voltage begins to rise. When the output voltage exceeds a certain value, the automatic voltage regulator becomes controllable and the output voltage approaches the rated setting value. During this time, voltage detection relay 4
operates, and the normally closed contact 4b is opened, so the initial excitation circuit 11 is turned off, and the generator 1 is thereafter operated by the automatic voltage regulator.

The above-mentioned initial excitation switch 13 can be operated both automatically and manually. In the case of automatic operation, the switch 13 itself is turned off by the output of the voltage detection relay 4, and a contact is made in the initial excitation circuit 11. Many do not insert 4b,
Further, even when the switch 13 is manually operated, the contact 4b may not be provided.

(Problems to be Solved by the Invention) However, in any case, in order to establish the initial voltage of an alternator using an automatic voltage regulator based on the conventional shunt-wound thyristor phase control method, a separate DC power supply and Therefore, in cases where there is no DC power supply, such as when driving an engine generator with an air start method, it is necessary to prepare a dedicated DC power supply for initial excitation. Ta.

The present invention eliminates the above-mentioned drawbacks in the initial excitation means of the conventional self-excited alternator, and makes it possible to establish a voltage at the start of operation of the self-excited alternator without separately providing a dedicated DC power supply. The present invention attempts to provide a certain excitation device.

(Means for Solving the Problems) In order to solve the above problems, the present invention makes it possible to self-establish the generator voltage by using the slight residual voltage of the alternator. a field winding of an alternator, an automatic voltage regulator for supplying an exciting current to said field winding in steady state, and an automatic voltage regulator connected in series with said field winding to an output bus of the alternator; and a self-exciting voltage self-establishing circuit.

(Function) In the above configuration, a small amount of current flows through the field winding due to the residual voltage of the alternator, and as the generator output voltage starts to rise, the current in the field winding increases. Thereafter, the same process repeats itself, and due to the combination of cause and effect, the generator voltage rapidly rises and becomes self-established, and the alternating current generator enters operation by the automatic voltage regulator.

(Embodiments) Hereinafter, one embodiment and other embodiments of the excitation device for an alternating current generator of the present invention will be described in detail in order with reference to FIGS. 1 to 3 and the like.

(One embodiment of the excitation device for an alternator of the present invention) (First embodiment)
(Fig. 2) Fig. 1 shows an embodiment using a single-pair kneading thyristor control system, and as a means for embodying the main features of the present invention,
A voltage self-establishing circuit 16 that performs initial excitation between, for example, the W phase and the U phase of the output bus of the alternating current generator 1 is connected in series with the field winding 10 .

In the illustrated example, this voltage self-establishment circuit 16 includes a normally closed contact 4b that is opened by energization of the voltage detection relay 4, an initial excitation current adjustment resistor 17, and a backflow prevention diode 18 connected in series. It consists of

7 is a single-phase half-wave rectifier circuit of the automatic voltage regulator;
Thyristor 8 and flywheel diode 9 as shown in the figure
It consists of Other circuits or elements in the device shown in FIG. 1 whose configuration and function are basically the same as those shown in FIG. 4 are as follows:
The same reference numerals as in FIG. 4 are used, and the explanation thereof will be omitted.

At this point, the thyristor 8 is uncontrollable, but due to the residual voltage of the generator 1, in the illustrated example, during a period in which the voltage of the W phase is higher than that of the U phase, the generator W phase - normally closed contact 4b - is adjusted. Resistor 1
A small amount of current flows through 7-backflow prevention diode 18-field winding 10-generator U phase, and the generator voltage starts to rise, so the above current increases further. Second
The figure shows the state in which the field voltage and field current (initial excitation current) rise during this period, and the field voltage is proportional to the generator voltage and becomes a single-phase half-wave rectified type. , the field current increases while being smoothed by the inductance of the field winding 10 and the action of the flywheel diode 9 in the rectifier circuit. Note that FIG. 2 is illustrated on the assumption that the rotation speed of the generator 1 is constant and the voltage is established. In this way, the cause and effect combine to cause the generator voltage to rise rapidly, and the automatic voltage regulator also starts control operation, approaching the rated voltage. Since the voltage detection relay 4 is activated and the contact 4b is opened, the voltage is self-established and the automatic voltage regulator starts operating.

The residual voltage of the above-mentioned generator is often about 2V or more in normal generators, and in brushless generators, which are currently the mainstream of generators, the iron core material of the AC exciter (usually silicon steel plate) Considering this, this value can be easily secured, and it can be said that the production cost of the generator will hardly increase due to securing this residual voltage.

(Another embodiment of the excitation device for an alternating current generator according to the present invention) (Fig. 3) Fig. 3 shows an embodiment using a single-phase mixed bridge control system, in which the rectifier circuit 7 is composed of two thyristors 8a s 8
The full-wave rectifier circuit is composed of a bridge circuit consisting of a diodes 8c and 8d, and its voltage self-establishment function is the same as that of the embodiment shown in FIG.

In the embodiments shown in FIGS. 1 and 3, the voltage self-establishment circuit 16 is connected between two lines of the output bus of the generator 1, but in the case of an asymmetrical Y-connection multiphase AC power supply, the voltage self-establishment circuit 16 is connected between the two output bus lines of the generator 1. The circuit may be connected between one of the phases and the neutral wire.

In implementing the present invention, the generator 1 can be either brushed or brushless. Furthermore, in the above-mentioned embodiment, the generator 1 is directly connected to the automatic voltage regulator, but even when an excitation transformer is used in a high-voltage generator, the residual voltage is equivalent to the secondary side of the excitation transformer. If approximately 2V or more is secured at , the present invention can be applied in the same manner as described above.

Furthermore, if you want to establish the voltage after a certain signal is input, or if you want to establish the voltage manually, insert an automatic or manual voltage establishment switch in series with the voltage self-establishment circuit 16, respectively. do it.

(Effects of the Invention) As described above, according to the present invention, by utilizing the residual voltage of the generator as an excitation device for a self-excited alternating current generator, a simple and simple DC power supply device is not required. Depending on the configuration, voltage can be self-established at the start of operation.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of an excitation device for an alternating current generator according to the present invention, FIG. 2 is a waveform diagram showing rising states of field voltage and field current in the device of FIG. 1, and FIG. 4 is a system diagram of another embodiment of the excitation device for an alternator according to the present invention, and FIG. 4 is a system diagram of a conventional excitation device. Explanation of symbols 1: AC generator, 4: Voltage detection relay, 4b: Normally closed contact, 5: Automatic voltage regulator control circuit, 6 Two voltage setting device,
7: Rectifier circuit, 10: Field winding, 16: Voltage self-establishment circuit, 17: Initial excitation current adjustment resistor, 18: Backflow prevention diode 7. Figure 1 Figure 2 1 hour

Claims (2)

[Claims] (1) A field winding of an alternator; an automatic voltage regulator that supplies exciting current to the field winding in a steady state; an excitation device for a self-excited alternator, comprising: a voltage self-establishing circuit connected to; (2) The voltage self-establishment circuit is a circuit in which a normally closed contact of a voltage detection relay connected to the output bus, an initial excitation current adjustment resistor, and a backflow prevention diode are connected in series. (1) An excitation device for the self-excited alternating current generator.