JP2640641B2 - AC generator voltage droop control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage drooping control device for an alternator using an automatic voltage regulator for controlling a terminal voltage of an alternator 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 constantly controlled by an automatic voltage regulator, a load such as a pump motor or a fan motor is directly driven. In this case, a large current exceeding the rating flows transiently through the AC generator due to the starting current of the induction motor, so it is necessary to control the voltage of the AC generator with an automatic voltage regulator to keep it constant. The rotation speed of the prime mover decreases, and the frequency of the alternator decreases. In extreme cases, the engine may be stopped. In order to avoid this phenomenon, a method of smoothly starting the induction motor using an automatic voltage control device that performs V / F constant control in which the terminal voltage of the alternator changes substantially in proportion to the rotation speed of the prime mover is used. Was used.

However, when it is necessary to quickly start the pump motor and the fan motor, the above-described constant V / F control has a long time until the start is completed, and the motor cannot be started quickly. . Further, when the AC generator and the motor load are paired, the above-described constant V / F control is possible. As described above, the frequency drop of the AC generator occurs, and another load connected to the AC generator is affected by the frequency drop. Therefore, it is necessary to select a prime mover having a capacity that can continuously withstand the direct drive of the motor, and there is a problem that a large-sized power generator is required.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has as its object to provide a large-sized power generator which can be used as a power generator even when a motor is quickly inserted directly around a rated frequency and started. It is an object of the present invention to provide a voltage drooping control device of an AC generator that can suppress a frequency drop of a prime mover without using a motor.

Another object of the present invention is to provide a pump motor and a fan motor having different characteristics in accordance with the characteristics of each control object in order to smoothly start even when the load is connected to an AC generator. Another object of the present invention is to provide a voltage drooping control device for an alternator that can easily change settings during operation.

[0006]

In order to achieve the above object, a first aspect of the present invention is to control a prime mover, an AC generator directly connected to the prime mover, and a constant terminal voltage of the AC generator. An automatic voltage regulator, an AC current detection circuit for detecting an output AC current of the AC generator, an AC current / voltage conversion circuit for converting the detected AC current to an AC voltage, and an output of the AC current / voltage conversion circuit. A DC voltage conversion circuit for converting an AC voltage to a DC voltage and smoothing the signal; and a signal for drooping the output voltage of the DC generator in accordance with an output signal of the DC voltage conversion circuit. A voltage drooping control device for an AC generator having a voltage drooping circuit input to a circuit, wherein the voltage drooping circuit outputs an output voltage of the AC generator at a rated current of the AC generator or more. A voltage droop start point setting circuit capable of variably setting a voltage droop start point to be dropped, and a droop amount of a voltage with respect to the generator AC current when the AC generator current flows beyond the voltage set by the voltage droop start point setting circuit. And a droop rate variable circuit capable of variably setting the voltage droop amount of the AC generator.

According to a second aspect of the present invention, in the voltage drooping control device for an AC generator according to the first aspect, the voltage drooping start point setting circuit and the voltage drooping amount setting circuit are constituted by operational amplifiers.

According to a third aspect of the present invention, in the voltage drop control device for an AC generator according to the first aspect, a detector used for an AC current detection circuit for detecting an output current of the AC generator is:
It is an AC CT or a Hall element type CT.

According to a fourth aspect of the present invention, there is provided a voltage drooping control device for an AC generator according to the first aspect of the present invention, further comprising a detector for detecting an active power of the AC generator. It is characterized in that it is supplied to a voltage droop circuit instead of a signal.

According to a fifth aspect of the present invention, in the voltage drop control device for an AC generator according to the first aspect, the AC generator is a generator of a brushless excitation type to which an AC exciter and a rotary rectifier are added. It is characterized by.

[0011]

The voltage drooping control device for an AC generator according to the present invention detects an output current of the AC generator when a large current flows at the time of starting a fan motor, a pump motor load or the like connected to the AC generator. The voltage of the AC generator is drooped at a value equal to or higher than the value set by the droop start point setting circuit. At this time,
The voltage drooping start point is set so that the voltage droops when the voltage becomes equal to or higher than the value set by the voltage drooping start point setting circuit in consideration of the starting current at the time of starting the fan, the pump motor load, and the like. Do not allow the voltage to drop when completed. Thus, the frequency drop of the prime mover can be suppressed.

Further, the set value of the voltage droop start point can be varied by a variable resistor. Here, fan motors with different characteristics
Even if a pump motor load or the like is to be controlled, the voltage drooping start point can be easily changed with a variable resistor. Also,
Even if the performance of the same fan motor, pump motor load, or the like is deteriorated due to the elapse of the operation time, the voltage droop start point can be easily changed using the variable resistor to match the deteriorated performance.

Furthermore, the voltage droop rate, which is the ratio of the voltage droop to the output current of the alternator, can also be varied. Changing the voltage droop start point will also change the voltage droop end point, but depending on the characteristics of the AC generator, even if the voltage droop start point is changed, if the voltage droop end point is desired to be kept constant, the voltage It becomes possible by changing the droop rate, and can be easily realized in a variable resistor. Also, the voltage droop amount (voltage droop limit point) determined in consideration of the actual starting current of the fan and the pump motor can be easily changed by the variable resistor according to the performance of the fan motor, the pump motor load and the like. . Therefore, the application that can be applied to one type of voltage drooping control device can be expanded by adjusting the variable resistor.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, a voltage drooping control device 100 to which the present invention is applied
FIG. 3 showing a connection configuration between an automatic voltage control device (hereinafter abbreviated as AVR) 200 and the automatic voltage control device 200 will be described.

In FIG. 3, 1 is a prime mover and 2 is a prime mover 1.
An AC generator 3 directly connected to the AC generator 3 is an AC CT of an AC current detection circuit for detecting an output AC current of the AC generator 2. Since the AVR 200 is well known, a detailed description thereof will be omitted.

Output voltage VD of voltage drooping control device 100
Is input to the error amplification amplifier 60 of the AVR 200.
In the error amplification amplifier 60, a generator detection voltage VG obtained by stepping down the AC voltage of the AC generator 2 by the detection transformer 50 and a reference voltage VS set by a voltage reference circuit are subtracted. The output of error amplifier 60 is input to phase control circuit 70, and the output of AVR 200 controls field winding 2a of 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 100 is 0 V, the normal AVR
During operation, the voltage of the alternator 2 is controlled to a constant rated voltage. Motors such as fans and pumps are directly inserted and started,
When a current equal to or greater than the rated current flows through the alternator 2, an output signal VD is output from the voltage drooping control device 100, and the error amplifier circuit controls the reference voltage VS as if the detected voltage of the alternator increased. As a result, the AVR 200 causes the output voltage of the AC generator 2 to drop.

FIG. 1 is a block diagram of a voltage drooping control device for an AC electric machine according to an embodiment (claim 1) of the present invention. The same parts as those in FIG. Is omitted.

In FIG. 1, reference numeral 4 denotes a resistor of an AC current / voltage conversion circuit for converting an AC current detected by the AC CT 3 into an AC voltage. The DC voltage conversion circuit includes diodes 5a to 5d that perform single-phase full-wave rectification on the AC voltage and convert the AC voltage into a DC voltage.
And a resistor 6 and a capacitor 7 for smoothing the rectified DC voltage.
And outputs a DC voltage proportional to the output current of the AC generator.

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 of the AC generator is connected to a resistor 8 connected to the output of the DC voltage conversion circuit. Are connected in series, then a variable resistor 9 is connected in parallel, and a zener diode 10 is connected in series. A variable resistor 11, a zener diode 12, and a variable resistor 13 are connected in parallel to the output of the voltage droop start point setting circuit to constitute a droop amount setting circuit. This droop amount setting circuit, when the AC generator current that is equal to or greater than the value set by the voltage droop start point setting circuit flows,
Is a circuit for setting the amount of voltage droop.

Next, the operation of this embodiment will be described.
After the AC current detected by the AC CT 3 is converted into an AC voltage by the resistor 4, the AC voltage is rectified by a DC voltage conversion circuit including diodes 5 a to 5 d, a resistor 6 and a capacitor 7, and the smoothed DC voltage is Device 8 and variable resistor 9
When the voltage becomes equal to or higher than the current value set by the voltage drooping start point setting circuit, the Zener voltage of the Zener diode 10 is output. Here, the Zener diode is an element that exhibits an infinite resistance value when the voltage applied thereto is equal to or lower than the Zener voltage, and has a zero resistance value when the voltage equal to or higher than the Zener voltage.

When the voltage applied to the Zener diode 10 is low, the resistance value of the Zener is infinite, so that the voltage across the variable resistor 9 is applied across the Zener diode 10 by the voltage division of the variable resistor 9 and the resistor 8. . The point at which the voltage applied to the variable resistor 9 and the voltage applied to the Zener diode 10 match is the voltage drooping start point. When the output current of the alternator 2 further increases, a voltage droop signal starts to be output.

Therefore, the magnitude of the output current of the AC generator that can output the Zener voltage of the Zener diode 10 can be changed by the value of the variable resistor 9. For example, the standard set value is set to 150% of the rated current of the alternator 2. At this time, when the resistance value of the variable resistor 9 is increased, the Zener voltage is output at a value smaller than the standard set value. Therefore, the voltage droop start point has a value smaller than the standard set value. Conversely, when the resistance value of the variable resistor 9 is reduced, a value larger than a standard set value is required to output a Zener voltage. Therefore, the voltage droop start point has a value larger than the standard set value. Here, the Zener voltage of the Zener diode 10 and the resistance value of the variable resistor 9 are
For example, if it is selected to be equivalent to 150% of the rated current of the alternator 2, the Zener diode 10 is in the off state when the current of 150% or less of the rated current of the alternator 2 flows, and the voltage drooping control device 100 Is 0V.

Next, the AC generator 2 is supplied with 150% of the rated current.
When the above current flows, the Zener diode 10 is turned on, and the output voltage of the voltage drooping control device 100 increases in proportion to a current of 150% or more of the rated current of the AC generator 2. The rate of this increase can be varied. Thus, the output voltage is limited by the voltage limit of the variable resistor 11, the zener diode 12, and the variable resistor 13, and the voltage droop amount is determined.

The voltage across the variable resistor 9 is divided by a Zener diode 10 and a variable resistor 11, and the Zener voltage of the Zener diode 12 is output from the voltage across the variable resistor 11. When the variable resistor 11 is changed, the combined resistance value of the variable resistors 9, 11, and 13 changes, and the output voltage of the voltage drooping control device 100 with respect to the output current of the AC generator 2 changes. Further, the variable resistor 11
When the resistance value of the variable resistor 11 is set to be large, the output voltage with respect to the output current of the AC generator 2 becomes large, and when the resistance value of the variable resistor 11 is set small, the output voltage with respect to the output current of the AC generator 2 becomes small. From the above, it is possible to change the voltage droop rate (the droop slope) which is the ratio of the droop amount of the output voltage to the output current of the AC generator 2 after the voltage droop start point.

FIG. 2 shows the output voltage characteristics of the voltage drooping control device 100 described above with respect to the generator output current. Here, as an example, the voltage droop amount is set in the droop amount setting circuit so that the voltage droop start point setting circuit starts drooping at the generator output current of 150%, thereby setting the voltage limit start point to 300%. The characteristics are shown by the solid line in FIG. When the variable resistor 9 is set such that the voltage droop start point X changes to X ′ from this characteristic diagram, the voltage droop end point Y also changes at the same time, so that the voltage droop end point of the variable resistor 11 becomes 300%. The voltage droop rate as follows. Also,
The voltage droop amount is set by the variable resistor 13. As described above, the voltage droop start point, the droop amount, and the droop rate can be set according to the application and are variable. The setting of the voltage droop start point, the droop amount, and the droop rate are respectively performed by the variable resistors 9, 11, 1
3, the range of use can be easily expanded with one type of voltage control device.

(Other Embodiments) In the above embodiment, the configuration of the voltage droop control device shown in FIG. 1 is a simple discrete circuit configuration. However, the present invention is not limited to this. The same effect can be obtained even if the droop amount setting circuit is constituted by a PO amplifier (corresponding to claim 2).
In the above embodiment, the voltage drooping control device is configured by hardware, but the same effect can be obtained by realizing the voltage drooping control device by software using a CPU.

In the above embodiment, the output signal of the voltage drooping control device is subtracted from the error amplifier circuit of the automatic voltage regulator, but the same applies to the configuration in which the output signal is subtracted from the voltage reference circuit of the automatic voltage regulator. The same effect can be obtained even if the effect is subtracted from the detection circuit.

Further, although the AC current detection circuit for detecting the output current of the AC generator uses the AC CT, the same effect can be obtained by using a Hall element type CT (corresponding to claim 3). The same effect can be obtained by detecting the active power instead of the output current of the AC generator (corresponding to claim 4). In the above embodiment, the AC generator does not include an exciter. However, the present invention can also be applied to a brushless excitation type generator to which an AC exciter and a rotary rectifier are added (corresponding to claim 5).

[0030]

As described above, according to the present invention,
If a large current flows when starting the fan motor, pump motor load, etc. connected to the AC generator, the output current of the AC generator is detected, and when the current exceeds the value set by the voltage droop start point setting circuit, the AC power is generated. Drop the machine voltage. The voltage drooping start point is set so that the voltage droops when it becomes a certain value or more in consideration of the starting current at the time of starting the fan, pump motor load, etc.When the start is completed, the voltage droops. Frequency drop can be suppressed. Therefore, even when the motor is quickly inserted directly around the determined frequency as the power generating device without using a large power generating device, the frequency drop of the prime mover can be suppressed.

Further, since the set value of the voltage drooping start point can be varied by the variable resistor, even if a fa motor, a pump motor load, etc. having different characteristics are to be controlled, the voltage drooping start point can be easily set by the variable resistor. Settings can be changed. Furthermore, even when the performance of the same fan motor, pump motor load, or the like is deteriorated due to the elapse of the operation time, the voltage droop start point can be easily changed using a variable resistor to match the deteriorated performance. it can. Also, the voltage droop rate, which is the ratio of the voltage droop to the output current of the alternator, can be varied. When changing the voltage droop start point, the voltage droop end point also changes, but depending on the performance of the AC generator, when the voltage droop start point is changed, the voltage droop end point is desired to be kept constant. It becomes possible by changing the voltage droop rate, and can be easily realized in a variable resistor.
Also, the voltage droop amount (voltage droop limit point) determined in consideration of the actual starting currents of the fan and the pump motor can be varied by the variable resistor, so that it can be easily changed according to the performance of the fan motor, the pump motor load and the like. I can do things. Therefore, the application that can be applied to one type of voltage drooping control device can be expanded by adjusting the variable resistor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a voltage drooping control device of an AC generator according to an embodiment of the present invention.

FIG. 2 is an output voltage characteristic diagram of the voltage drooping control device of the present invention with respect to the output current of the AC generator.

FIG. 3 is a connection configuration diagram of a voltage drooping control device to which the present invention is applied and an automatic voltage adjustment device.

[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: resistor for setting voltage droop start point, 9 ...
Variable resistor for setting voltage droop start point, 10 ... Zener diode for setting voltage droop start point, 11 ... Variable resistor for setting voltage droop rate, 12 ... Zener diode for setting voltage droop amount, 13 ... Variable for setting voltage droop amount Resistor, 100: Voltage drooping control device, 50: Detection transformer, 60: Error amplification amplifier, 70: Transfer control circuit, 200: AVR.

Claims (5)

(57) [Claims] 1. A motor, an AC generator directly connected to the motor, an automatic voltage regulator for controlling a terminal voltage of the AC generator to be constant, and an AC current for detecting an output AC current of the AC generator. A detection circuit, an AC current / voltage conversion circuit for converting the detected AC current to an AC voltage, a DC voltage conversion circuit for converting an output AC voltage of the AC current / voltage conversion circuit to a DC voltage, and smoothing the DC voltage conversion circuit; A voltage drooping control device for an alternator including a voltage drooping circuit for inputting a signal for drooping an output voltage of a DC generator to an error amplifier circuit or a voltage reference circuit of the automatic voltage regulator according to an output signal of the circuit. The voltage drooping circuit is capable of variably setting a voltage drooping start point at which the output voltage of the AC generator droops above the rated current of the AC generator. And a droop rate variable circuit capable of variably setting a ratio of a voltage droop amount to the generator AC current when an AC generator current greater than that set by the voltage droop start point setting circuit flows; and And a droop amount setting circuit capable of variably setting a voltage droop amount of the machine. 2. The voltage drooping control device for an AC generator according to claim 1, wherein the voltage drooping start point setting circuit and the voltage drooping amount setting circuit are configured by an operational amplifier. . 3. The voltage drop control device for an AC generator according to claim 1, wherein a detector used in an AC current detection circuit for detecting an output current of the AC generator is an AC CT or a Hall element type CT. A voltage drooping control device for an alternator. 4. The voltage drop control device for an AC generator according to claim 1, further comprising a detector for detecting an active power of the AC generator, wherein the active power signal of the detector is replaced with an AC current signal and the voltage is dropped. A voltage drop control device for an alternator, which is supplied to a circuit. 5. An AC generator according to claim 1, wherein said AC generator is a brushless excitation type generator to which an AC exciter and a rotary rectifier are added. Machine voltage droop control device.