JPH0360343A - Uninterruptible power-supply device - Google Patents

Abstract

PURPOSE:To miniaturize a enclosure and improve the using efficiency of a enclosed equipment by providing each primary side of an insulating transformer with a current transformer, and by detecting the load current of a by-path circuit and an inverter circuit with a current transformer. CONSTITUTION:To the load of an inverter 3, the one side of the primary winding of an insulating transformer 5 is connected via a switch 7B inserted into a non-grounded line side, and to a by-path circuit 6, the other end of the primary winding is connected on a load side via a switch 7A. To the grounded line side of the by-path circuit 6 and the grounded line side of the load side of the inverter 3, a current transformer 9 having two primary windings is inserted, and the load side current of the by-path circuit 6 and the inverter 3 is detected by the one current transformer. The current detected by the current transformer 9 is recognized on the load side of the by-path circuit 6 or the inverter 3 by the change-over of the switches 7A, 7B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an uninterruptible power supply equipped with a bypass circuit.

(Prior Art) In Figure 2, which shows the main circuit connection diagram of a conventional uninterruptible power supply equipped with a bypass circuit, the input side terminal of the uninterruptible power supply surrounded by a dotted line is connected to the noise of the uninterruptible power supply. A filter 2 is connected, and the AC input side of an inverter 3 is connected to the load side of this noise filter 2.
A backup storage battery 4 is connected to the DC input side of the converter via a switch (not shown). On the other hand, inverter 3
An insulating transformer 5 is connected to the output side of the insulating transformer 5, and the grounding line side of the load side of the insulating transformer 5 is connected to the electronic computer as the load 8 of this uninterruptible power supply via the output side terminal of the uninterruptible power supply. The ungrounded line side of the load side of the isolation transformer 5 is connected to the output side terminal of the uninterruptible power supply to the load 8 via the switch 7B.

Further, a bypass circuit 6A is connected between the AC input side of the inverter 3 and the output side of the uninterruptible power supply, and a switch 7A is connected to the ungrounded line of the bypass circuit 6A.

In addition, the box of the load 8 is grounded via the ground terminal, and the input terminal of the uninterruptible power supply is connected to the ground line side or the AC 100 V
is connected to the commercial power supply 1.

In the uninterruptible power supply configured as described above, during normal operation, AC power supplied from the commercial power supply 1 is converted to DC by a rectifier (not shown) in the inverter 3, and then converted to a predetermined voltage by an inverter circuit (not shown). The frequency is reversely converted into alternating current and supplied to the load 8 from the isolation transformer 5 and the switch 7B, and at the same time, the storage battery 4 is charged. If the inverter 3 fails, synchronization with the commercial power source 1 is confirmed, switches 7A and 7B are switched, and power is supplied from the commercial power source 1 to the load 8.
If the voltage of the commercial power source 1 drops, a switch (not shown) is switched, and the power of the storage battery 4 is reversely converted by the inverter 3 to supply power to the load 8.

By the way, in a load such as a computer, if there is a potential difference of 0.5 V or more between the potential on the ground line side and the ground terminal of the box, it will cause a failure, so it is required to reduce this difference.

However, in the uninterruptible power supply with such a configuration, a voltage is induced across the noise filter 2 by the high frequency component of the noise generated from the inverter 3, and the potential on the ground line side of the load 8 is increased via the bypass circuit 6A. There is a risk that the potential difference between the ground terminals of the box will also rise.

For this reason, an uninterruptible power supply as shown in Figure 3 is used.

This involves inserting the isolation transformer 5A into the bypass circuit 6B and connecting the ground line on the secondary side of the isolation transformer 5B on the load side of the inverter 3 to the ground via the ground terminal on the box of the uninterruptible power supply. This prevents the voltage of the ground side line of the load 8 from increasing due to the induced voltage induced by the noise filter 2.

(Problem to be Solved by the Invention) However, in the uninterruptible power supply having such a configuration, a current transformer is installed on the primary side of the isolation transformer 5B to detect overcurrent due to an accident between the inverter 3 and the load 8. In addition, a current transformer 9A is also required on the primary side of the isolation transformer 5A due to overcurrent and the following reasons.

That is, as shown in Fig. 4, when computer loads 8A and 8B are connected in parallel to the uninterruptible power supply,
If a load 8B is applied while the load 8A is operating, and the voltage of the inverter 3 decreases due to the charging current to the capacitor in the load 8B, the inverter circuit is switched to the bypass circuit as shown in Figure 5 after the charging current is reduced. This is because it is necessary to detect the return current when returning to the current state.

Therefore, as shown in Fig. 3, it is possible to insert the current transformer 11 shown by the dotted line inside the output terminal of the uninterruptible power supply, but if this happens, the elements inside the inverter 3 may be damaged. Even if a DC overcurrent flows, it may not be detected.

Then, since two current transformers are required, not only the storage space increases and the box becomes large, but also the current transformer 9A has a low utilization rate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain an uninterruptible power supply device equipped with a bypass circuit that can reduce the size of the box and increase the utilization rate of the stored equipment.

[Structure of the Invention] (Means and Effects for Solving the Problems) The present invention provides an uninterruptible power supply in which isolation transformers are inserted into the load side of an inverter and a bypass circuit, respectively. By inserting a switch on the primary side of the isolation transformer on the load side of the inverter and the load side of the inverter, and providing one current transformer with a primary winding connected to each primary line of these isolation transformers, This is an uninterruptible power supply device using bypass circuit materials that detects the load currents of the bypass circuit and inverter circuit with a single current transformer, reduces the external size of the box, and increases the utilization rate of the current transformer.

(Example) Hereinafter, one example of the uninterruptible power supply device of the present invention will be described with reference to the drawings. However, parts that overlap with FIGS. 2 to 5 are omitted.

In FIG. 1, one side of the two primary windings of an isolation transformer 5 is connected to the load of the inverter 3 via a switch 7B inserted on the non-grounded line side, and the bypass circuit 6 is connected to a switch 7A. The other sides of the two primary windings are connected to the load side via the insulating transformer 5, and the secondary side of the isolation transformer 5 is directly connected to the output side terminal of the uninterruptible power supply.

On the other hand, a current transformer 9 having two primary windings is inserted and connected to the ground line side of the bypass circuit and the ground line side of the load side of the inverter 3, respectively.

In the bypass circuit type uninterruptible power supply with such a configuration, the bypass circuit 6 and the current on the load side of the inverter 3 can be detected with one current transformer, so it is possible to increase the size of the box of the uninterruptible power supply. This can be prevented and the utilization rate of the current transformer can be increased. Note that whether the current detected by the current transformer 9 is from the bypass circuit or the load side of the inverter is determined by the switch 7A.
, 7B can be easily recognized by the control system that issues a switching command.

[Effects of the Invention] As described above, according to the present invention, in an uninterruptible power supply in which an isolation transformer is provided on the load side of an inverter and a bypass circuit, switching is performed on the bypass circuit on the primary side of the isolation transformer and the load side of the inverter. Since one current transformer with a primary winding connected to the transformer and each primary side is provided, it is possible to obtain an uninterruptible power supply device with a bypass circuit that allows the device to be miniaturized.

[Brief explanation of drawings]

Fig. 1 is a main circuit connection diagram showing one embodiment of the uninterruptible power supply of the present invention, Figs. 2 and 3 are main circuit connection diagrams showing a conventional uninterruptible power supply, and Fig. 4 is a main circuit connection diagram showing a conventional uninterruptible power supply. A connection diagram showing the operation of an uninterruptible power supply. FIG. 5 is a diagram showing the operation of a conventional uninterruptible power supply. 3...Inverter 5...Isolation transformer 6...Bypass circuit 7A, 7B...Switch 9...Current transformer (8733) Agent Patent attorney Yoshiaki Inomata (and others)
1 person)

Claims (1)

[Claims] In an uninterruptible power supply in which isolation transformers are inserted in the load side of an inverter and a bypass circuit, respectively, switching is performed on the primary side of the isolation transformer in the bypass circuit and the primary side of the isolation transformer on the load side of the inverter. 1. An uninterruptible power supply device characterized in that a single current transformer is provided, the primary winding being connected to each of the primary lines.