JPH079594Y2 - Inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an inverter device for supplying AC power to a plurality of loads.

[Conventional technology]

FIG. 2 is a main circuit connection diagram showing a conventional example of an inverter device that supplies AC power to a plurality of loads.

This FIG. 2 shows that the AC power from the AC power supply 2 is converted into DC power by the first rectifier 11, this DC power is converted into AC power by the first inverter 14, and this AC power is supplied to the first load 15. The second rectifier 21 and the second inverter.
The 24 also converts the AC power from the AC power supply 2 into the second load.
AC power is being supplied to 25.

The AC power supply 2 may have a power failure for a very short time (hereinafter referred to as a momentary power failure) due to a lightning strike, a line switching, or the like. It is troublesome and complicated to stop and restart No.24 and No.24, and it is desirable to avoid such an operation stop due to a power failure depending on the load.

Therefore, the so-called DC intermediate circuit, which connects the DC sides of the first rectifier 11 and the first inverter 14, or the DC sides of the second rectifier 21 and the second inverter 24, to each other, the capacitors 12 and 13, or the capacitors. If 22 and 23 are connected and the power failure of the AC power supply 2 is a momentary power failure, the electric charges charged in these capacitors are discharged during this momentary power failure, so that the AC power source 2 fails. However, each of the inverters 14 and 24 is operated to continue supplying power to the loads 15 and 25.

As described above, when the capacitor is used as a backup power source during a momentary power failure, even if the inverters that supply AC power to multiple loads are separate, there is only one rectifier that supplies DC power to these inverters. Then, connecting a large-capacity capacitor to the DC side of this rectifier has a simpler configuration than the conventional example circuit shown in FIG. 2, so that the cost can be reduced.

However, if the allowable voltage fluctuation range is different for each load, the DC intermediate circuit cannot be shared, that is, the rectifier cannot be shared.

[Problems to be solved by the device]

Therefore, inevitably, an inverter device composed of a rectifier, an inverter, and a backup capacitor as shown in FIG. 2 is separately prepared for each load. Such a device also has a backup capacitor. It has the drawback of requiring extra, making the device bulky and expensive.

Therefore, an object of the present invention is to reduce the size and cost of the device by sharing a common DC power source side of an inverter that separately supplies alternating current to loads having different voltage fluctuation allowable values.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, an inverter device of the present invention comprises a rectifier that is connected to an AC power source and outputs DC, a first inverter that is directly connected to a DC output side of the rectifier, and the rectifier. A second inverter connected to the DC output side via a diode, a capacitor connected to the DC input side of the first inverter, and a DC input side of the second inverter and the diode. And a capacitor to be connected.

[Action]

This invention supplies DC power output from one rectifier to a plurality of inverters. A separate diode is inserted between this rectifier and each inverter, and a backup capacitor is connected to each diode. By separately connecting the inverter and the inverter, it is possible to operate in conformity with loads having different voltage fluctuation allowable values.

〔Example〕

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention.

In FIG. 1, the AC power from the AC power supply 2 is converted into DC power by the rectifier 3 and then output to the DC intermediate circuit. A first inverter 14 for supplying AC power to the first load 15, a second inverter 24 for supplying AC power to the second load 25, and capacitors 4, 5 and 7 are connected to the DC intermediate circuit. However, the group of the capacitors 4 and 5 and the second inverter 24 and the group of the capacitor 7 and the first inverter 14 are separated by the diode 6.

Now, it is assumed that the second load 25 has a larger capacity than the first load 15, and the allowable voltage fluctuation range is larger for the second load 25. When the AC power supply 2 is supplying AC power, the capacitors 4, 5 and 7 are in a charging completed state.
Here, when the AC power supply 2 fails, each capacitor reduces its voltage according to a predetermined time constant while discharging its charge to the first load 15 and the second load 25. At this time, the capacitors 4 and 5 supply electric power to the second load 25 having a large capacity, and the voltage thereof is lowered relatively quickly. However, since the diode 6 is inserted, the charge of the capacitor 7 is the second. It does not flow to the load 25 and discharges only to the first load 15.

[Effect of device]

DC power is supplied from a common rectifier to the DC side of each inverter that separately supplies AC power to loads with different allowable voltage fluctuation ranges. It is a separate circuit, and a backup capacitor in case of power failure is installed at the DC input end of each inverter. With this configuration, even if a large-capacity capacitor is installed as a backup for a load with a small allowable voltage fluctuation value, the inserted diode prevents the charge of this capacitor from being discharged to another load. Since the rectifier that supplies DC power can be shared and the backup capacitor can be installed in an appropriate place with an appropriate capacity, the device becomes large and expensive. Can be avoided.

[Brief description of drawings]

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention, and FIG. 2 is a main circuit connection diagram showing a conventional example of an inverter device for supplying AC power to a plurality of loads. 2 ... AC power supply, 3 ... Rectifier, 4,5,7,12,13,22,23 ... Capacitor, 6 ... Diode, 11 ... First rectifier, 14 ... First inverter, 15 ... First load, 21 ... Second 2 rectifier, 24 ... second inverter, 25 ... second load.

Claims (1)

[Scope of utility model registration request] 1. A rectifier that is connected to an AC power source to output DC, a first inverter that is directly connected to the DC output side of the rectifier, and a DC output side of the rectifier that is connected via a diode. A second inverter, a capacitor connected to the DC input side of the first inverter, and a capacitor connected between the DC input side of the second inverter and the diode. Characteristic inverter device.