JPS6318420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a power supply device that supplies power from a commercial power source and an inverter device to the same load. This invention relates to an operating method that prevents fluctuations in voltage, distortion of voltage waveforms, and cross currents from commercial power sources to inverter devices.

Generally, an inverter device is used as a power supply device that supplies constant-frequency, constant-voltage power to a load. Commercial power supply (AC power supply) as shown in the diagram
1 and the output side of the inverter device 2, respectively.
and a second static switch 31 and 32 are connected to each other, and the output sides of the first and second static switches 31 and 32 are used in common to supply power to the same load 4. . Further, the first and second static switches 31 and 32 each have thyristors 33 and 34 connected in antiparallel.
and 35, 36.

In the above configuration, the normal load 4 has a second
Inverter device 2 via static switch 32
Constant frequency and constant voltage power is supplied. During maintenance and inspection of the inverter device 2 or when an accident occurs, the second static switch 32 is shut off and the first static switch 31 is turned on to supply power from the commercial power source 1 to the load 4. .

When the maintenance and inspection of the inverter device 2 is completed in this state, or when the accident in the inverter device 2 is recovered, the first static switch 31 is shut off and the second static switch 32 is turned on, and the inverter device is restarted. 2 will supply power to the load 4.

However, in this method, when the power applied to the load 4 is switched from the commercial power supply 1 to the inverter device 2, the inverter device 2 suddenly changes from a no-load state to a full-load state, resulting in a phenomenon in which the output voltage of the inverter device 2 drops significantly ( There was a problem that caused a voltage drop phenomenon.

This invention was made in view of the above points,
The first object of the present invention is to provide a method for operating a power supply device that prevents the voltage drop phenomenon that occurs when switching the power supply to a load from a commercial power source to an inverter device.
Another object of the present invention is to provide a method of operating a power supply device that suppresses cross current from the commercial power source to the inverter device, which occurs when power supply to a load is switched from the commercial power source to the inverter device.

In order to achieve these objects, the present invention synchronizes the inverter device with the commercial power source when switching the power supply to the load from the commercial power source to the inverter device, and also provides a first and the thyristors of the second static switch in the same direction are made conductive, and the control angle of the thyristor of the first static switch is gradually increased to supply power to the load from the commercial power source to the inverter device. It is made to switch.

Furthermore, the inverter device is synchronized with the commercial power supply and the thyristors of the first and second static switches connected to the commercial power supply and the output side of the inverter device are made conductive in the same direction, and the second A resistor is connected in parallel to both ends of the first static switch, and the control angle of the thyristor of the first static switch is gradually increased to switch the power supply to the load from the commercial power source to the inverter device. It is configured to suppress cross current from the commercial power source to the inverter device.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of a power supply device in which the present invention is implemented.

In the figure, 1 is a commercial power supply (AC power supply), 2
are inverter devices, and first and second static switches 31 and 32 are installed on the output sides of these devices, respectively.
and connect these first and second static switches 3
Connect the output sides of 1 and 32 in common and use the same load 4
to supply power. Further, the first and second static switches 31 and 32 are respectively constituted by thyristors 33, 34 and 35, 36 connected in antiparallel. Further, current detectors 5 and 6 are provided on the output sides of the commercial power supply 1 and the inverter device 2, respectively, and detection signals from these current detectors 5 and 6 are supplied to the inverter device 2, and the inverter device 2 is connected to the commercial power source. It is synchronized to 1. Also 7
is a soft start device that responds to the operation of the inverter device 2, and from this soft start device 7 to the first and second static switches 31 and 32,
Gate signals A and B are supplied respectively.

In the above configuration, the constant frequency and constant voltage power normally required by the load 4 is supplied from the inverter device 2 via the second static switch 32. When performing maintenance or inspection on this inverter device or in the event of an accident, the second static switch 32 is shut off, the first static switch 31 is turned on, and the load 4 is connected to the commercial power supply. Provides more power.

Next, when the maintenance and inspection of the inverter device 2 is completed, or when the accident in the inverter device 2 is recovered, the power supply to the load 4 is switched from the commercial power source 1 to the inverter device 2.

When performing a switching operation in which the power supply to the load 4 is switched from the commercial power supply 1 to the inverter device 2, the inverter device 2 is first started, and based on the detection signals of the current detectors 5 and 6, the inverter device 2 is switched from the commercial power source 1 to the inverter device 2. The inverter device 2 is synchronized with the power source 1, and the output voltage of the inverter device 2 is set to be the same as or slightly lower than the output voltage of the commercial power source 1. Next, the soft start device 7 supplies the thyristors 33 and 34 of the first static switch 31 with gate signals A (gate signals shown in FIGS. 3b and 3c) whose control angle gradually increases, and the second
Thyristors 35 and 36 of the static switch 32
A gate signal B (the gate signal shown in FIGS. 3e and 3f) is supplied to each of the thyristors 33 and 34 in the same direction as those described above to make them conductive in the same power supply cycle.

The thyristor 35 or 36 is fired by the gate signal shown in FIG. It flows to the load 4 via. During the same half cycle of the voltage waveform, the gate signal shown in FIG. 3b or c is supplied to the first static switch 31, thereby igniting the thyristor 33 or 34. When the first static switch 31 becomes conductive, the thyristors 35 and 36 of the second static switch 32 are connected to the first static switch because the impedance of the inverter device 2 is larger than the impedance of the commercial power supply 1. 31 is conductive, a reverse voltage is applied, and the inverter device 2
The output current is forcibly commutated by the output current output from the commercial power supply 1, cut off as shown in Figure 3g, and then transferred from the commercial power supply 1 to the load 4 as shown in Figure 3d. Current flows, and when the output current of this commercial power supply 1 becomes zero, natural commutation occurs again, and current is supplied to the load 4 from the inverter device 2 via the second static switch 32 from the beginning of the next half cycle. It turns out. When the first static switch becomes conductive, the output current of the inverter device 2 is cut off by forced commutation again, and power is supplied to the load 4 from the commercial power supply 1, and the same operation is repeated thereafter. . In this state, the control angle of the gate signal supplied to the thyristors 33 and 34 is gradually increased by the soft start device 7 as shown in FIG. 3b and c.
As the control angle of this gate signal increases, the output current of the commercial power supply 1 (shown in Figure 3 d) gradually decreases, and the output current of the inverter device 2 (shown in Figure 3 g) gradually increases. However, power is finally supplied to the load 4 only from the inverter device 2. After all, even during such switching of the power supply, the current flowing through the load 4 is a sinusoidal current without any change as shown in FIG. 3a.

As described above, the output current is transferred from the commercial power supply to the inverter device in a soft manner, and the power supply to the load 4 is switched from the commercial power supply 1 to the inverter device 2 in a soft manner.

In addition, in the above-mentioned embodiment, when it is actually put into practical use, it is necessary to solve the problem of so-called cross current. That is, for example, when transitioning from a half cycle in which a gate signal is applied to the thyristors 33 and 35 to the next half cycle, after stopping the supply of the gate signal to the thyristors 33 and 35, and before the thyristors 33 and 35 are cut off. This is because when a gate signal is applied to the thyristor 36, a cross current flows from the commercial power supply 1 to the inverter device via the thyristor 33 and the thyristor 36, and an overcurrent flows to the inverter device 2, causing a failure. For this reason,
When the thyristor 36 is turned on after the thyristor 33 has stopped, or the thyristor 35 is turned on after the thyristor 34 has stopped, there is a pause period _t1 between each gate signal, as shown in FIGS. 4b and 4c. It becomes necessary.

By providing such a pause section _t1 , it is possible to prevent cross current from the commercial power supply 1 flowing into the inverter device 2, but by providing this pause section _t1 , the output current also increases as shown in Figure 4a. Part of it will be cut off. As a result of this cutoff of the output current shown in FIG. If a cyclic sine wave voltage is required, there are disadvantages such as an adverse effect on the load 4.

FIG. 5 is a block diagram of a power supply device that solves the above-mentioned problems, and in addition to the configuration shown in FIG. The bodies are connected in parallel.

In the above configuration, the operation method when switching the power supply to the load 4 from the commercial power supply 1 to the inverter device 2 is almost the same as that of the power supply device shown in FIG. When starting the inverter device 2 and operating the soft start device 7, the relay contact 9 is turned on. As a result of this ON operation of relay contact 9, FIG.
and the sixth in the pause period of the gate signal shown in c.
As shown in Figure a, current flows from the inverter device 2 to the load 4 through the series connection of the relay contact 9 and the resistor 8, and the output voltage supplied to the load 4 becomes a complete cycle voltage. Further, the cross current flowing between the commercial power source 1 and the inverter device 2 is limited by the resistor 8. Note that the relay contact 9 is opened when the soft start by the soft start device 7 is completed, that is, when the load 4 is disconnected from only the inverter device 2.
This is done when power is supplied to the

As described above, according to the present invention, since the switching operation of the output current from the commercial power supply to the inverter device can be smoothly transferred, the load voltage does not drop and the inverter device is not adversely affected. Not at all.

Further, according to the present invention, the cross current flowing between the commercial power source and the inverter device is limited by the resistor connected in parallel to the second static switch, so that no overcurrent flows to the inverter device. In addition, the voltage supplied from the inverter to the load has a smooth voltage waveform, and a complete cycle voltage waveform is applied to the load, reducing the negative impact on the load when switching the power supply from commercial power to the inverter. It is possible to perform extremely stable power supply switching operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a general power supply device, FIG. 2 is a block diagram showing the configuration of a power supply device to which the present invention is applied, FIG. 3 is a signal waveform diagram of each part to explain its operation, and FIG. Figure 4 is a signal waveform diagram showing the relationship between output current and gate signal, Figure 5 is a block diagram showing the configuration of another power supply device to which the present invention is applied, and Figure 6 is an output waveform diagram to explain its operation. be. 1...Commercial power supply, 2...Inverter device, 31
...First static switch, 32... Second static switch, 33-36... Thyristor, 4...
Load, 7... Soft start device, 8... Resistor,
9... Switch means.

Claims (1)

[Claims] 1. A commercial power source, a first static switch consisting of an anti-parallel connected thyristor connected to the output side of the commercial power source, an inverter device, and a first static switch connected to the output side of the inverter device. and a second static switch made of anti-parallel connected thyristors, the power supply device supplies power to the same load by sharing the output sides of the first and second static switches, wherein the inverter device is connected to the inverter device as described above. synchronized with a commercial power supply and causing thyristors in the same direction of the first and second static switches to conduct;
and the control angle of the thyristor of the first static switch is gradually increased to switch the power supply to the same load from the commercial power source to the inverter device. Method. 2. A first static switch consisting of a commercial power source, an anti-parallel connected thyristor connected to the output side of this commercial power source, an inverter device, and an anti-parallel connected thyristor connected to the output side of this inverter device. and a second static switch configured to supply power to the same load by sharing the output sides of the first and second static switches, wherein a switch is connected in parallel to the second static switch. a resistor is connected through a means to synchronize the inverter device with the commercial power source and to cause thyristors in the same direction of the first and second static switches to conduct; A power supply device characterized in that the control angle of the thyristor of the switch is gradually increased and the switch means is closed to switch the power supply to the same load from the commercial power source to the inverter device. how to drive.