JPH0721074Y2 - AC uninterruptible power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention constantly supplies electric power having a predetermined voltage and frequency to the output, and does not break when a commercial power source fails or drops in voltage. More specifically, the present invention relates to an improvement of an uninterruptible power supply device that can output the power via an inverter and can output a commercial power supply by a changeover switch.

2. Related Art and Problems Thereof FIG. 2 and FIG. 3 show a conventional example of a constant inverter power supply system in an AC uninterruptible power supply. In FIG. 2, the AC input from the commercial power source 1 is constantly converted into DC by the rectifier 2 and converted into AC again by the inverter 6,
It is electrically isolated at 12 and its power is supplied to the load at output 11 via switch 8. When the commercial power supply fails or the voltage drops, power is supplied from the battery 5 to the output 11 via the inverter 6, the transformer 12 and the switch 8. If the inverter should fail, the switch 7 is turned on and the switch 8 is turned off so that the commercial power is continuously supplied to the output through the bypass circuit 10.

Similarly in FIG. 3, the AC input from the commercial power source 1 is constantly converted to DC by the rectifier 2, insulated by the high-frequency link DC / DC converter 13, converted into a constant voltage, and converted again to AC by the inverter 6, and then the switch 8 The power is supplied to the load from the output 11 via. If the commercial power supply fails or the voltage drops, the battery 5 drives the inverter 6, the switch 8
To feed the load. If the inverter should fail, switch 7 is turned on immediately and switch 8 is turned off.
Then, the commercial power is continuously supplied to the output through the bypass circuit 10.

However, since the conventional uninterruptible power supply of this type includes the bypass circuit, the transformer 12 of FIG. 2 and the high frequency link DC / DC converter 13 of FIG.
It was necessary to make electrical insulation somewhere from the input to the output. If this is not done in the conventional circuit, the power supply is short-circuited in the mode shown in FIG. 4 and the device fails. However, since the transformer 12 of FIG. 2 is for commercial power supply frequency, the weight and volume are large, and it is becoming unsuitable for the present situation where the device is becoming smaller and lighter.

The high-frequency link DC / DC converter shown in FIG. 3 has a complicated circuit configuration because it internally converts direct current into high-frequency alternating current, electrically insulates it with a high-frequency transformer, and then converts it back into direct current. It also comes with the drawback of high costs.

Means for Solving the Problems In view of the above-mentioned drawbacks of an AC uninterruptible power supply device having a conventional bypass circuit, the present invention is lightweight, compact and inexpensive without insulating the input and the output by simple means. With the aim of providing a simple uninterruptible power supply, a switch that turns ON / OFF the positive and negative lines that connect the rectifier and the inverter, a switch that switches the inverter output and commercial power supply, and other input V phase and output V phase By providing a switch to turn ON / OFF, the main circuit part of the uninterruptible power supply is made non-insulated.

Embodiment FIG. 1 shows an embodiment of an AC uninterruptible power supply system of a constant inverter power supply according to the present invention.

AC input from commercial power supply 1 is always connected to rectifier 2 and non-isolated DC
The DC / DC converter 3 converts the DC power to a smooth voltage, the ON / OFF function controllable switch 4 is used, and the inverter 6 converts the AC power to a commercial frequency AC power having a predetermined voltage again. Power is supplied to the load from output 11 via.

Here, as shown in FIG. 5, the control signal of the switch 8 is immediately turned off as soon as the output of the inverter exceeds the output for some reason.
Then, the control signals of the switches 7 and 9 are turned on, and at the same time, the switch 4 is forcibly turned off to perform bypass power feeding.

Then, the inverter output becomes normal again, and after a certain confirmation time, the control signal of the switch 8 is turned on, and at the same time, the switch 7 is turned on.
And the control signal of the switch 9 is turned off. After a lapse of a half cycle or more of the power supply frequency, the switch 4 is turned on to return to the inverter power supply.

By controlling the ON / OFF timing of these switches in this way, it is possible to omit the provision of a circuit for electrically insulating the main circuit portion of the uninterruptible power supply.

As described above, the present invention provides a constant inverter power supply type uninterruptible power supply device having a bypass circuit, in which the inverter output and the commercial power supply are U-phase without electrical insulation by an inverter transformer or a high frequency link DC / DC converter. By providing a switch for switching, a switch for turning on and off the input V phase and output V phase, and a switch for turning on and off the positive and negative lines of the non-isolated DC / DC converter section respectively, it is possible to reduce the size and weight. It can have the same functions as conventional products.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of an AC uninterruptible power supply of the present invention, FIGS. 2 and 3 are circuit diagrams showing a conventional example, and FIG.
FIG. 5 is a diagram showing a power supply short-circuit mode when the conventional device is not insulated, and FIG. 5 is a diagram showing switch timing. 1 ... Commercial power supply, 2 ... Rectifier, 3 ... Non-insulated DC / DC converter, 4 ... ON / OFF function control switch, 5 ... Battery, 6 ... Inverter, 7,8,9 ... ON Function enable control switch, 10 …… Bypass, 11 …… Output

Claims (1)

[Scope of utility model registration request] 1. A rectifier for converting a commercial AC power source into DC power, a DC / DC converter for transforming the DC power, and a DC / DC converter therefor.
A battery that matches the output of the DC converter, an inverter that converts its DC power into AC power having a predetermined voltage and frequency, and a switch that switches the power supplied to the output from a commercial power source or an inverter output, In an uninterruptible power supply capable of supplying required power to a load without interruption when the commercial power supply fails or drops in voltage, the positive line and the negative line between the DC / DC converter and the inverter are turned on respectively. An uninterruptible power supply characterized by having an ON / OFF function control switch and an ON function control switch on each of the inverter output U line and bypass circuit V line.