JP3400960B2 - Automatic 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 automatic voltage controller, and more particularly to an automatic voltage controller having a power saving function for reducing power consumption by controlling the voltage of a commercial power source and / or a function for compensating the voltage corresponding to a drop in the voltage. Regarding the control device.

[0002]

2. Description of the Related Art Conventionally, in this kind of power saving device, voltage compensating device or voltage controlling device, a series winding or a shunt winding is formed by using a transformer having a plurality of single winding parts wound around the same iron core. In this configuration, the shunt winding is provided with a tap, the tap is switched by a thyristor (SCR) or a relay, and an arbitrary voltage is selected to perform voltage conversion. As such an example, JP-A-6-178462 and JP-A-8-1
The device described in Japanese Patent No. 91542 is known. However, in such a configuration, a large surge current flows due to the emission of residual magnetism when the tap is turned off, and a large surge voltage is momentarily generated when the tap is connected. Since such a large current or high voltage may damage the thyristor or the like, it has been a cause of cost increase such as using a thyristor having a high breakdown voltage. Further, in such a conventional configuration, when the tap is released, there is a risk that the imbalance of the load directly affects the phase balance of the transformer and the input / output voltage becomes abnormally high. .

In such a conventional device, windings are alternately combined in order to balance the phase voltages. However, if a neutral wire is taken into a winding in a transformer, a large amount of current will flow into one phase. Since there is a risk of damaging the transformer itself, the neutral wire is not taken in, it is put into a through state, and only voltage conversion is performed.

On the other hand, as another conventional device, an actual flat plate 2-3 is used.
Japanese Patent Laid-Open No. 8-3351.
There is one disclosed in Japanese Patent No. In the devices described in these publications, the shunt winding and the series winding are wound on separate iron cores. Therefore, as described above, problems such as surge voltage, surge current, and imbalance between phases that occur when the both are wound on the same iron core do not occur. However, the shunt winding (shunt transformer) has a multi-winding structure, and the shunt winding V
The capacity represented by A increases and the volume also increases. Furthermore, if the shunt transformer has a multi-winding structure, the conversion efficiency is poor, the no-load current and the load loss increase, and the power loss of the circuit reaches 5 to 10% of the whole. This violates the original purpose of the device that controls the voltage to save power. Further, in Japanese Utility Model Laid-Open No. 2-35426, since a plurality of separate windings are provided on the secondary side of the shunt transformer, the number of switching elements such as thyristors for switching the windings increases and control becomes complicated. There is also the problem of becoming.

[0005]

Therefore, according to the present invention, a large surge current and a large surge voltage are not generated, the phase balance of the transformer is not lost even if there is an imbalance of the load, and the shunt winding is An object of the present invention is to provide an automatic voltage control device that does not increase the capacity or volume, has little power loss due to shunt winding, and can easily control a switch element.

[0006]

To achieve the above object, the present invention has a structure in which a shunt winding and a series winding are wound on separate iron cores, and the shunt winding is a single winding structure. One of a plurality of taps of the wire is selected by the switch means and an arbitrary voltage is supplied to the secondary winding of the transformer constituted by the series winding to control the voltage.

That is, according to the present invention, a plurality of output voltages can be obtained in a single winding to which the input voltage supplied to the input terminal is applied.
Used for selecting the shunt winding with because taps, one of said plurality of different output voltages of the shunt winding
And a plurality of switch means in which thyristors are connected in antiparallel, a primary winding connected between the input terminal and the output terminal, and an iron core of the primary winding. A series transformer having a secondary winding, a means for supplying the output of the switch means to the secondary winding, and a control signal for detecting the input voltage and controlling the on / off operation of the switch means. And a control means for controlling the automatic voltage control device.

Further, according to the present invention, a plurality of output voltages can be obtained in a single winding to which the input voltage supplied to the input terminal is applied .
For selecting one of the plurality of different output voltages of the shunt winding and a shunt winding for
A plurality of first switch means having a configuration in which thyristors are connected in antiparallel, a primary winding connected between the input terminal and the output terminal, and a plurality of taps wound around an iron core of the primary winding. A series transformer having a secondary winding, a second switch means for selecting one of the plurality of taps of the secondary winding to supply the output of the first switch means, and detecting the input voltage. , And a control means for generating a control signal for controlling the on / off operation of the first and second switch means.

Also, the switch means or the first
Further comprising switch means for switching between in-phase and anti-phase when supplying the output of the switch means to the secondary winding,
This is a preferred embodiment of the present invention.

Furthermore, the output voltage of the shunt winding is
It is a further preferred embodiment of the present invention that the reactor is interposed in the portion to be supplied to the next winding.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an R-phase circuit portion of a single-phase three-wire automatic voltage controller as a preferred embodiment of the automatic voltage controller according to the present invention. A series winding 16-1 is inserted between the R-phase input terminal 10 and the R-phase output terminal 20. When the series winding 16-1 is the primary winding, the secondary winding 16-2 is provided in common with the iron core 16-3. Secondary winding 16
-2 is provided with a plurality of (five in this example) taps. Series winding 16-1, secondary winding 16-2, and iron core 1
6-3 constitutes a series transformer 16. The neutral wire input terminal 12 is directly connected to the neutral wire output terminal 22.
The input terminals 10 and 12 are respectively connected to both ends of a shunt winding 14 having a single winding structure (single winding transformer). The shunt winding 14 is provided with one intermediate tap.

Both terminals and the center tap of the shunt winding 14 are respectively thyristors 18-1 and 18 as switching means.
It is connected to both terminals of the reactor 24 via -2 and 18-3. The taps of the reactor 24 are connected to each tap and one terminal of the secondary winding 16-2 of the series transformer 16 via thyristors 28-1, 28-2, 28-3, 28-4, 28-5. There is. The other terminal of the secondary winding 16-2 of the series transformer 16 is connected to the input terminal 10 and the input terminal 12 via thyristors 26-1 and 26-2 as switching means.

The control circuit 30 is connected to the output terminals 20 and 22, and detects the voltage between the output terminals 20 and 22 to obtain the required output voltage, that is, each switch, that is, thyristors 18-1 to 18-. 3,28-1 to 28-5,2
A control signal for controlling the on / off operation of 6-1 and 26-2 is generated. FIG. 2 is a block diagram showing the internal configuration of the control circuit 30. As shown in the figure, the control circuit 30 includes a reference voltage setting unit 32 for the user to set a desired output voltage V5, an output voltage detecting unit 34 for detecting the output voltage between the output terminals 20 and 22, and an output voltage detecting unit 34 for detecting the output voltage. An interface (I / F) 36 for receiving a signal, a CPU 38 connected to the interface 36, a memory 40 for receiving and storing a control pattern from the outside, and a control signal for controlling ON / OFF of each thyristor by an output signal of the CPU 38. For generating three thyristor control signal generators 42-
1, 42-2, 42-3.

FIG. 3 is a flow chart for explaining the operation of the CPU 38 shown in FIG. When the power is turned on, CP
U38 first reads the control pattern stored in the memory 40 in step S1. This control pattern is in the form of a list of numerical values that give how much the input voltage is lowered or raised about the reference voltage which is the target value of the output voltage. That is, as shown in FIG. 4, when the rating of the input voltage is 100V, the reference voltage is 97V, and the range of the actual input voltage is 8V.
When the voltage is controlled in steps of 1V in the range of 7V to 97V, a pattern for increasing or decreasing the input voltage by a voltage which is a difference between the input voltage and the reference voltage is provided. Therefore, this control pattern can be arbitrarily changed according to the expected range of the input voltage and the desired voltage adjustment range. In FIG. 4, when the input voltage is higher than the reference voltage, the automatic voltage control device of the present invention operates as a power saving device, while when the input voltage is lower than the reference voltage, it operates as a voltage compensation device.

FIG. 5 is a circuit diagram in which the reactor and the thyristor of FIG. 1 are omitted in order to explain the operation principle of the automatic voltage controller of the present invention. In FIG. 1, the reactor 24 is the side of the shunt winding 14 and the secondary winding 1 of the series transformer 16.
It plays the role of a shock absorber between 6-2. That is,
As will be described later, a surge voltage generated by turning on / off the thyristor is branched into a forward direction and a reverse direction of the thyristor, and in that direction, through a reactance, from a tapped midpoint
It can be reduced by allowing the current to flow in the direction of the next winding 16-2. However, in the case where such surge voltage does not affect, the reactor 24 can be omitted.

In FIG. 5, the output voltage V5 is determined by the following function with respect to the input voltage V1. V5 = V1 ± (V2 · V4 / V3) where V2 is the voltage of the series winding 16-1, V3 is the output voltage of the shunt transformer 14, and V4 is the voltage of the secondary winding 16-2 of the series transformer 16. Is. In FIG. 5, arrows I1, I2
I3 and I4 respectively indicate the directions of current at a certain moment. Now, as shown in FIG. 5, from the input terminal R to the series winding 1
When the currents I1 and I2 flow into the 6-1 and the shunt winding 14, respectively, a counter electromotive force is generated in the shunt winding 14 to generate the current I2.
A current I3 in the opposite direction to the current flows through the secondary winding 16-2 of the series transformer 16 via the tap.

On the other hand, in the secondary winding 16-2, the series winding 16
A secondary voltage is induced by the current I1 flowing in −1, and a current I4 flowing in the direction of the shunt winding 14 is generated. Here, the currents I3 and I4 are in opposite directions, and some of them are canceled. Therefore, the voltage V4 drops below the voltage originally generated by the voltage V2 of the series winding. Therefore, the voltage of the secondary winding 16-2 reduces the voltage V2 of the series winding 16-1 and thus the output voltage V5 = V1 + V2.
The configuration shown in FIG. 5 is a case where the input voltage V1 is lowered to the output voltage V5, while when the input voltage V1 is raised to the output voltage V5, the currents I3 and I4 are in the same direction. So that the thyristors 26-1, 26- of FIG.
It is only necessary to switch between 2.

Next, the specific operation of the automatic voltage controller of FIG. 1 will be described with reference to FIG. FIG. 6 shows how the input voltage is raised or lowered by the on / off operation of each thyristor in FIG. First, as explained in FIG. 4, when the input voltage V1 is higher than the reference voltage Vref, the thyristor 26-2 is turned on and the thyristor 26-1 is turned off so that the automatic voltage control device of the present invention operates as a power saving device. Becomes On the other hand, when the input voltage V1 is lower than the reference voltage Vref, the thyristor 26-1 is turned on and the thyristor 26-2 is turned off to operate as a voltage compensator. 6A shows the case where the device is operated as a voltage compensation device (thyristor 26-1 is on, thyristor 26-2 is off), and FIG. 6B is the case where it is operated as a power saving device (thyristor 26). -2 is on, and thyristor 26-1 is off).

In FIG. 6, in the two tables, thyristor 1
"8-1 to 18-3" indicates that only the corresponding thyristor is on (conducting state) and the other thyristors are off (non-conducting state).
The fact that 8-1 to 28-5 are on indicates that only the corresponding thyristor is on (conduction state) and the other thyristors are off (non-conduction state). Therefore,
For example, in FIG. 6A, when the thyristor 18-3 is on and the thyristor 28-3 is on, the voltage is increased by 8V. The minus sign in (B) of FIG. 6 means a decrease in voltage. As can be seen from FIG. 6, in the present embodiment, it is possible to control in steps of 1 V from 0 V to 10 V at the time of rising, and similarly from 0 V to −10 V at the time of falling.
Up to 1V can be controlled.

Returning to the flowchart of FIG. 3, step S
After the pattern is read in 1, the reference voltage Vref is read in step S2. Then, in step S3, the output voltage V5
To read. Then, in step S4, it is determined whether or not the output voltage V5 is higher than the reference voltage Vref, and if YES, the voltage decrease is controlled according to the pattern in step S5. On the other hand, if NO, the output voltage V5 is the reference voltage Vre in step S6.
It is determined whether or not it is lower than f, and if YES, control of voltage increase is performed according to the pattern in step S7. On the other hand, if NO, the process returns to step S4. When step S5 or S7 is completed, the output voltage V5 is changed to the reference voltage Vref in step S8.
If it is YES, the process returns. On the other hand, if NO, the process returns to step S4 to continue the voltage control.

As can be seen from the flow chart of FIG. 3 and the on / off mode of the thyristor for control of FIG. 6, the control is performed in the mode of FIG. 6 in steps S5 and S7 of the flow chart. That is, now, the output voltage V5 is 1
Assuming that the voltage is 05V, which is higher than the reference voltage Vref = 97V by 8V, a voltage drop of "-8V" in FIG. 6B is required, and the thyristor 26-2 is turned on to enter the drop mode. Further, the thyristors 18-1 and 28-3 are turned on. As a result, the output voltage V5 drops and 104
It approaches V. Then, this time, it is necessary to decrease the voltage by "-7V", and the thyristor 26-2 remains on.
The thyristors 18-1 and 28-3 are turned off, and at the same time, the thyristors 18-2 and 28-5 are turned on. in this way,
"-8V" → "-7V" → "-6V" → "-5V" →
"-4V" → "-3V" → "-2V" → "-1V" →
The thyristor on / off control is sequentially performed until the difference between the output voltage V5 and the reference voltage Vref disappears in the order of "0V".
The same applies when increasing the voltage.

FIG. 7 is a voltage waveform diagram showing the operating condition of the thyristor. Taking advantage of its characteristics, the timing of switching the thyristor generates a turn-off voltage when it receives a control signal (OFF command) to turn off the thyristor that is currently on. The thyristor of the next tap is turned on so as to switch to the next tap at the upper limit of 260 V in synchronism with the timing of the voltage generated when the current due to and the release current flows (ON command). The time from the off command to the on command is about 0.5 to 1 ms. With such an operation, the inrush current generated when the thyristors are switched does not affect the output voltage, and the breakdown voltage of each thyristor can be suppressed low.

In the above embodiment, the plurality of output voltages of the shunt winding 14 are selectively supplied to the secondary winding 16 of the series transformer 16.
-2, in addition to thyristors 18-1 to 18-3,
Thyristor 28-1 for selecting tap of secondary winding
28-5 are provided, the provision of the latter enables fine voltage adjustment as described with reference to FIG.
However, the thyristors 28-1 to 28-5 are omitted, and the tap of the reactor 24 is directly connected to one terminal of the secondary winding 16-2 (the terminal to which the thyristor 28-5 is connected in FIG. 1).
You may connect to. In this case, it becomes the same as the case where 28-5 is turned on in FIGS. When the taps of the reactor 24 are directly connected to the secondary winding 16-2 as described above, the output voltage V5 can be adjusted to a certain degree by increasing the number of taps provided in the shunt winding 14.

In the above embodiment, the automatic voltage control device of the present invention operates as a power saving device, and when the input voltage is lower than the reference voltage, it operates as a voltage compensating device. When only one of the compensating devices needs to operate, the thyristors 26-1 and 26-2 for switching the operation are unnecessary, and instead of these, the wires may be directly connected according to the required operation. In the above embodiment, the R phase in the case of the single-phase three-wire system has been described, but if the neutral line N is shared and two circuits similar to those in FIG. 1 are combined, a configuration as shown in FIG. 8 is obtained. . In addition, in FIG. 8, the winding portion is simply represented by a cross mark. Further, the present invention can be applied not only to a single-phase three-wire system but also to a single-phase two-wire system, a three-phase three-wire system, a three-phase four-wire system, and the like.

[0025]

As described above, according to the present invention, the shunt winding and the series winding are separated and wound on separate iron cores, and the shunt winding has a single winding structure. Since the output voltage is selectively supplied to the secondary winding of the series winding, there is no large surge current or large surge voltage, and the phase balance of the transformer is lost even if there is an imbalance in the load. There is no increase in the capacity and volume of the shunt winding, and there is little power loss due to the shunt winding.
An effect that the control of the switch element can be easily performed is achieved. Further, by providing a tap also on the secondary winding of the series winding and selecting a tap for supplying the output voltage of the shunt winding by the switch element, more fine voltage adjustment is possible. In this case, since a plurality of switch elements are provided and the voltage is changed little by little by switching the taps, there is an advantage that one switch element has a small voltage and a low withstand voltage can be used.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a preferred embodiment of an automatic voltage control device according to the present invention.

FIG. 2 is a block diagram showing an internal configuration of a control circuit 30 in FIG.

FIG. 3 is a flowchart illustrating an operation of a CPU 38 in FIG.

4 is a diagram showing a pattern of voltage control of the circuit of FIG.

5 is a circuit diagram in which the reactor and the thyristor of FIG. 1 are omitted in order to explain the operating principle of the automatic voltage control device of the present invention.

FIG. 6 is a diagram showing how the input voltage is raised or lowered by the on / off operation of each thyristor in FIG.

FIG. 7 is a voltage waveform diagram showing an operating condition of the thyristor.

FIG. 8 is a circuit diagram in the case where an automatic voltage controller for a single-phase three-wire system is configured by combining two circuits similar to those in FIG. 1 with a common neutral wire N.

[Explanation of symbols]

10 R-phase input terminal 12 Neutral wire (N) input terminal 14 Shunt winding 16 Series transformer 16-1 Series winding 16-2 Secondary winding 16-3 Iron core 18-1, 18-2, 18 -3, 28-1, 28-2,
28-3, 28-4, 28-5 Thyristor (switch means) 20 R-phase output terminal 22 Neutral wire (N) output terminal 24 Reactor 26-1, 26-2 Thyristor (switch for switching in-phase and anti-phase) Means) 30 control circuit (control means) 36 interface (I / F) 38 CPU 42-1, 42-2, 42-3 thyristor control signal generation unit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Takahashi 2-21-4 Shin-Kamata, Ota-ku, Tokyo Within Japan Pan-Agreed Co., Ltd. (56) Reference JP-A-11-95846 (JP, A) JP-A 11-134041 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G05F 1/14 H01F 29/04 H02P 13/06

Claims (5)

(57) [Claims] 1. A shunt winding having a tap for obtaining a plurality of output voltages in a single turn to which an input voltage supplied to an input terminal is applied; and a plurality of the shunt windings. For selecting one of the different output voltages, in which the thyristors are connected in anti-parallel
A plurality of switch means having the above configuration, a primary winding connected between the input terminal and the output terminal, a series transformer having a secondary winding wound around an iron core of the primary winding, and the switch means An automatic voltage control device comprising: a means for supplying the output of the above to the secondary winding; and a control means for detecting the input voltage and generating a control signal for controlling the on / off operation of the switch means. 2. The automatic voltage control device according to claim 1, further comprising switch means for switching between in-phase and anti-phase when the output of the switch means is supplied to the secondary winding. 3. A shunt winding having taps for obtaining a plurality of output voltages in a single turn to which an input voltage supplied to an input terminal is applied, and the plurality of shunt windings. For selecting one of the different output voltages, in which the thyristors are connected in anti-parallel
A plurality of first switching means, a primary winding connected between the input terminal and the output terminal, and a secondary winding wound around an iron core of the primary winding and having a plurality of taps. A series transformer and one of the plurality of taps of the secondary winding are selected to select the first
Automatic voltage control having: a second switch means for supplying an output of the switch means; and a control means for detecting the input voltage and generating a control signal for controlling the on / off operation of the first and second switch means. apparatus. 4. The output of the first switch means is set to the second output.
Claims further comprising a third switching means for switching the phase and anti-phase when supplied to said secondary winding via the switching means
Item 5. The automatic voltage controller according to Item 3 . 5. The automatic voltage control device according to claim 1, wherein a reactor is provided in a portion that supplies the output voltage of the shunt winding to the secondary winding.