JP2710020B2 - AC generator voltage controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC generator voltage control device for controlling a terminal voltage of an AC generator directly connected to a prime mover such as a diesel engine.

[0002]

2. Description of the Related Art Conventionally, in a power generator in which the terminal voltage of an AC generator directly connected to a prime mover such as a diesel engine is generally controlled by an automatic voltage regulator, a load such as a pump motor or a fan motor is directly driven. In such a case, a large current exceeding the rating transiently flows into the AC generator due to the starting current of the induction motor, and the automatic voltage regulator controls the voltage of the AC generator to be constant, but the prime mover rotates. The number decreases and the frequency of the alternator frequency drops. In extreme cases, the engine may be stopped. In order to avoid this phenomenon, a method for smoothly starting the induction motor using an automatic voltage regulator that performs V / f constant control in which the terminal voltage of the AC generator changes substantially in proportion to the rotation speed of the prime mover is used. Was used.

[0003]

However, when it is necessary to quickly start the pump motor and the fan motor, the conventional V / f constant control requires a long time until the start is completed.
There was a problem that the motor could not be started quickly. In addition, when the AC generator and the motor load are paired, the above-described control is possible.However, when the motor load is directly inserted around the rated frequency as the power generator and started, as described above, during the motor start period, There has been a problem that a frequency drop of the AC generator occurs and other loads connected to the AC generator are affected by the frequency drop. Therefore, it is necessary to select the prime mover to have a capacity that can continuously withstand the direct drive of the motor, which causes a problem that a large-sized power generator is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a voltage control system for an alternator capable of suppressing a frequency drop of a prime mover even when a motor is rapidly inserted directly around a rated frequency and started. It is to provide a device.

[0005]

In order to achieve the above object, an AC generator for controlling the terminal voltage of an AC generator directly connected to a prime mover by an automatic voltage regulator is provided. In the voltage control device, an AC current detection circuit for detecting the output current of the AC generator, an AC voltage conversion circuit for changing the current detected by the AC current detection circuit to a voltage, and an output voltage of the AC voltage conversion circuit a DC voltage converter for converting the rectified DC voltage, output of the AC generator
A voltage drooping start point setting circuit for setting a drooping start point of the force voltage, and an output current of the alternator being equal to or higher than a rated current value.
When the output voltage of the DC voltage conversion circuit exceeds the voltage droop start point set by the voltage droop start point setting circuit, the voltage droop that sets the voltage droop amount of a gradual characteristic curve according to the amount of current that has exceeded the voltage droop start point Amount setting circuit and the voltage droop amount setting
The output voltage of the voltage droop amount of the constant circuit is controlled by the automatic voltage regulator.
To the load, and the load is
The output voltage of the AC generator is lowered in accordance with the voltage drop quantity of the voltage droop amount setting circuit DOL startup, alternating onset
It is characterized in that it is configured to suppress the frequency drop of the electric machine and shorten the load startup time.

According to a second aspect of the present invention, in the voltage control device for an AC generator according to the first aspect, an output signal of the voltage drooping control device is added to an error amplifier circuit of the automatic voltage regulator. Features.

According to a third aspect of the present invention, in the voltage control device for an AC generator according to the first aspect, an output signal of the voltage drooping control device is added to a voltage reference circuit of the automatic voltage regulator. Features.

According to a fourth aspect of the present invention, in the voltage control device for an AC generator according to the first aspect, an output signal of the voltage drooping control device is added to a generator voltage detection circuit of the automatic voltage regulator. It is characterized by the following.

According to a fifth aspect of the present invention, in the voltage control device for an AC generator according to the first aspect, a detector used in the AC current detection circuit uses an AC CT or a Hall element type CT. I do.

According to a sixth aspect of the present invention, in the voltage control device for an AC generator according to the first aspect of the present invention, the voltage control apparatus is configured to supply active power of the AC motor at a rated current of the AC generator or more. .

[0011]

The voltage drooping control device according to the present invention detects an AC generator output current when a large current flows at the time of starting a fan motor, a pump motor load, etc. connected to the AC generator, and outputs the AC generator output current. Is greater than or equal to the current value set by the voltage droop point start setting circuit, a voltage droop signal is output. Therefore, by adding the output signal of the voltage drooping control device to, for example, an error amplifier circuit of the automatic voltage regulator, the terminal voltage of the AC generator is reduced while the motor is being started, and the generator output current is reduced by the completion of the start. When the current drops below the current value set by the voltage drooping point start setting circuit, the terminal voltage of the AC generator is returned to the rated voltage, whereby the frequency drop of the prime mover can be suppressed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, a circuit diagram of a voltage drooping control device of an AC generator to which the present invention is applied will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a prime mover, 2 denotes an AC generator directly connected to the prime mover, and 20 denotes a voltage drooping control device. Here, each component constituting the voltage drooping control device 20 will be described. Reference numeral 3 denotes an AC CT of an AC current detection circuit for detecting an output AC current of the AC generator 2;
A resistance of an AC current / voltage conversion circuit for converting the AC current detected by T3 into an AC voltage, 5a to 5d are diodes for converting a single-phase full-wave rectification of the AC voltage to a DC voltage, 6 is a resistor,
Reference numeral 7 denotes a capacitor, which constitutes a DC voltage conversion circuit including the diodes 5a to 5d, the resistor 6, and the capacitor 7, and outputs a DC voltage proportional to the output current of the AC generator.

Next, as a voltage drooping start point setting circuit for setting a voltage drooping start point for drooping the output voltage of the AC generator when the rated current of the AC generator is higher than the rated current, a resistor 9 is connected to the output of the DC voltage conversion circuit. Zener diodes 8 are connected in series. Further, a Zener diode 10 and a variable resistor 11 are connected in parallel to the output of the voltage drooping start point setting circuit, and when an AC generator current exceeding the voltage set by the voltage drooping start point setting circuit flows, the AC generator Is a droop amount setting circuit that sets the voltage droop amount of.

For example, if the zener voltage of the zener diode 8 is selected to be equivalent to 150% of the rated current of the alternator 2, the zener diode 8 is turned off when a current less than the rated current flows through the alternator 2. In this state, the output voltage of the voltage drooping control device 20 is 0V. Next, when a current of 150% or more of the rated current flows through the alternator 2,
The Zener diode 8 is turned on, and the output voltage of the voltage drooping control device 20 becomes 15 times the rated current of the AC generator 2.
It increases in proportion to the current of 0% or more. However, the output voltage is limited by the voltage limit by the Zener diode 10 and the variable resistor 11, and the amount of voltage droop is determined.

FIG. 2 is an output voltage characteristic diagram with respect to the generator output current of the voltage drooping control device 20 described above. FIG.
FIG. 5 is a characteristic diagram in which a voltage droop start point setting circuit is set to 150% and a voltage limit of a droop amount setting circuit is set to 300% as an example. It should be noted that the characteristic diagram in the figure is shown with the polarity of the output characteristic reversed for easy understanding. As described above, the voltage droop start point and the droop amount can be set according to the application, and can be further varied.

FIG. 3 is a circuit diagram of one embodiment (corresponding to claims 1 and 2) of the present invention, and the voltage drooping control device 20
FIG. 2 is a connection circuit configuration diagram of an automatic voltage control device (hereinafter referred to as AVR) 30. Since the AVR 30 has a known configuration, a detailed description thereof will be omitted.

In FIG. 3, an output voltage VD of the voltage control device 20 is added by an adder 32 described below and input to an error amplifier circuit 33 of the AVR 30. The error amplification circuit 33 adds the generator detection voltage VG obtained by stepping down the AC voltage of the AC generator 2 by the detection transformer 31 and the reference voltage VS set by the voltage reference circuit by the adder 32 and inputs the result. Configuration. The output of the error amplifier 33 is
The input to the phase control circuit 34 is output from the AVR 30, and controls the field winding 2a of the AC generator 2.

As an example, the reference voltage VS is set to a minus signal, the generator detection voltage VG is set to a plus signal, and the output signal VD of the voltage drooping control device is set to a plus signal. When the output signal of the voltage drooping control device 20 is 0 V, the normal AV
During the operation of R30, the voltage of the alternator 2 is controlled to a constant rated voltage. Next, when a motor such as a fan or a pump is directly inserted and a current equal to or greater than the rated current flows through the AC generator 2, an output signal VD is output from the voltage drooping control device 20, and the AC generator 2 is compared with the reference voltage VD. The error amplifying circuit 33 controls the detection voltage to increase, and as a result, AVR
30 causes the output voltage of the alternator 2 to drop.

(Other Embodiments) In the embodiment shown in FIG. 1, the voltage droop controller has a simple discrete circuit configuration. However, the voltage droop controller is not limited to this, and the voltage droop start point setting circuit and the voltage droop amount setting circuit are not limited to this. The same effect can be obtained even if the circuit is constituted by a 0P amplifier. Also, the method of realizing the voltage drooping control device by hardware has been described.
The same effect can be obtained by realizing with software using.

Further, the output signal of the voltage droop control device is:
Although the configuration is such that the addition is made to the error amplifier circuit of the automatic voltage regulator, the configuration is such that it is added to the voltage reference circuit of the automatic voltage regulator (corresponding to claim 3), and also the configuration which adds to the detection circuit (corresponding to claim 4). The same effect as in the above embodiment can be obtained.

Although an AC CT is used as an AC current detecting circuit for detecting an output current of the AC generator,
The same effect can be obtained by using a configuration using a Hall element type CT (corresponding to claim 5). Furthermore, the same effect can be obtained by using a configuration in which active power is used instead of the output current of the AC generator (corresponding to claim 6). In the embodiment, the AC generator has been described as not including the exciter. However, a brushless excitation type generator having an AC exciter and a rotary rectifier can be applied similarly to the embodiment.

[0024]

As described above, the voltage drooping control device of the present invention reduces the output current of the alternator when a large current flows when the load of the fan motor, the pump motor, etc. connected to the alternator starts. If the output current of the alternator becomes equal to or higher than the current value set by the voltage droop point start setting circuit, a voltage droop signal is output. As a result, the terminal voltage of the alternator is reduced while the motor is running, and the output current of the generator is reduced when the motor is started, and the current drops below the current value set by the voltage droop point start setting circuit. If possible, by returning the terminal voltage of the AC generator to the rated voltage, the frequency drop of the prime mover can be suppressed.
Therefore, even when the motor is quickly inserted directly around the rated frequency and started as a power generator without using a large-capacity power generator, the frequency drop of the prime mover can be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a voltage drooping control device of an AC generator to which the present invention is applied.

FIG. 2 is an output voltage characteristic diagram of the voltage drooping control device of FIG.

FIG. 3 is a circuit configuration diagram of an AC generator voltage control device according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Prime motor, 2 ... AC generator, 2a ... Field winding of AC generator, 3 ... AC CT, 4 ... Current / voltage conversion resistance, 5a-
5d: Rectifying diode, 6: Smoothing resistor, 7: Smoothing capacitor, 8: Zener diode for setting voltage droop start point, 9: Resistor for setting voltage droop start point, 10: Zener diode for setting voltage droop amount, 11 ... A variable resistor for setting a voltage droop amount, 20 a voltage droop control device, 30 an automatic voltage regulator (AVR), 31 a detection transformer, 32 an adder, 33 an error amplifier circuit, and 34 a phase control circuit.

Continuation of the front page (56) References JP-A-6-237543 (JP, A) JP-A-60-97000 (JP, U) JP-B1-32741 (JP, B2) JP-B-59-43909 (JP, B2) , B2) Jikken 34-20200 (JP, Y1)

Claims (6)

(57) [Claims] 1. An AC generator voltage control device for controlling a terminal voltage of an AC generator directly connected to a prime mover by an automatic voltage regulator, wherein the AC current detection circuit detects an output current of the AC generator. An AC voltage conversion circuit that converts a current detected by the AC current detection circuit into a voltage, a DC voltage conversion circuit that rectifies an output voltage of the AC voltage conversion circuit and converts the output voltage to a DC voltage, and an output of the AC generator. a voltage drop start point setting circuit for setting a vertical <br/> under the starting point of the voltage, the exchange
When the output current of the flow generator exceeds the rated current value and the output voltage of the DC voltage conversion circuit exceeds the voltage droop start point set by the voltage droop start point setting circuit, the current that has exceeded
A voltage droop amount setting circuit for setting a voltage droop amount of a gradual characteristic curve according to the amount , and a voltage of the voltage droop amount setting circuit.
The output voltage of the droop amount is input to the automatic voltage regulator,
Load direct start by dynamic voltage regulator
Sometimes, the output voltage of the AC generator is reduced according to the voltage droop amount of the voltage droop amount setting circuit, so that the frequency drop of the AC generator is suppressed and the load startup time is shortened. Generator voltage control device. 2. The alternator voltage control device according to claim 1, wherein an output signal of the voltage drooping control device is added to an error amplifier circuit of the automatic voltage regulator. Voltage control device. 3. An AC generator according to claim 1, wherein an output signal of said voltage drooping control device is added to a voltage reference circuit of said automatic voltage regulator. Voltage control device. 4. The voltage control device for an AC generator according to claim 1, wherein an output signal of the voltage drooping control device is added to a generator voltage detection circuit of the automatic voltage regulator. Generator voltage control device. 5. A voltage control device for an AC generator according to claim 1, wherein the detector used in the AC current detection circuit uses an AC CT or a Hall element type CT. Control device. 6. The voltage control device for an AC generator according to claim 1, wherein the active power of the AC motor is supplied at a rated current of the AC generator or more. apparatus.