JPH02299435A - Surge current supplying circuit - Google Patents

Abstract

PURPOSE:To prevent voltage fluctuation and/or noise trouble in a direct supply power source system by a method wherein a circuit, supplying a surge current having a high peak value generated upon starting a capacitor input type load connected in parallel, is provided. CONSTITUTION:When a capacitor input type load is connected to an AC non- service interruption power source device, a surge current having a high peak value is conducted to charge capacitors 12, 13 in the load. An inverter 1 is locked instantaneously by the operation of an overcurrent detector 23 provided in the output circuit of the inverter 1 while a control circuit 11 sends an ignition signal to gate circuits 21, 22 to put thyristors 14, 15 ON whereby an electric charge, charged in the capacitors 12, 13, is discharged to supply a peak current.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention supplies inrush current that occurs when a load is connected to an AC uninterruptible power supply (hereinafter referred to as UPS) that uses a constant inverter power supply system. The present invention relates to an inrush current supply circuit attached to a UPS that can perform

[Conventional technology]

The spread of computer-applied equipment and
As systems become more networked, capacitor input type loads are becoming more common as UPS loads.

When this capacitor input type load is started in parallel, a rush current with a large peak value flows, so in a conventional UPS with a bypass circuit, the load is switched to the bypass circuit side to protect the inverter from overcurrent.

[Problem to be solved by the invention]

As mentioned above, the inrush current switched from the inverter to the bypass circuit is transferred to the commercial AC power supply (
Hereinafter, it is referred to as direct power supply. ).

As a result, voltage fluctuations occur in the direct power supply system, causing problems such as a drop in the supply voltage to other connected devices and an increase in noise.

In order to solve the above-mentioned problems, the present invention provides a circuit that supplies inrush current with a large peak value that occurs when starting a capacitor input type load in parallel, thereby supplying inrush current from a direct power supply. The purpose of this is to prevent failures in the direct power supply system that occur during

[Means to solve the problem]

In order to achieve the above object, the present invention provides an AC uninterruptible power supply device of a constant inverter power supply type configured by an inverter equipped with a switch in an output circuit, a bypass circuit equipped with a switch connected in parallel, etc. A circuit consisting of a semiconductor switch in which a diode and a thyristor are connected in parallel between two input terminals of a bypass circuit and two output circuit terminals of an inverter, and
A circuit in which the above semiconductor switch and reactor are connected in series,
The primary side is connected in parallel to the input terminals of the two sets of semiconductor switches mentioned above, and both terminals of the secondary side are connected to the positive side of the capacitor through a diode, and a resistor is provided at the intermediate tap on the secondary side. A transformer connected to the negative side of the above two sets of capacitors via a diode, and
Two sets of parallel circuits, each of which has its positive side connected to the output side of the semiconductor switch via a thyristor, and whose negative side is connected to the output side of the semiconductor switch on the opposite side, and further of the inverter. The peak current is detected by an overcurrent detector installed in one line of the output circuit, and upon receiving this detection signal, the two sets of thyristors connected to the positive terminal of the capacitor and the two sets of thyristors forming the semiconductor switch are selected. ignite 2
This is an inrush current supply circuit for an AC uninterruptible power supply device consisting of a control circuit equipped with a set of gate circuits, and a control circuit equipped with a set of gate circuits.

[Effect]

When AC power is constantly supplied from an inverter to a general load, two capacitors connected to the secondary side of the transformer via diodes are charged by a transformer connected in parallel to the direct power supply. Ru.

When a capacitor input type load is applied as a UPS load, an inrush current with a large peak value flows to charge a capacitor inside the load.

The inverter is instantly locked by the activation of the overcurrent detector provided in the output circuit of the inverter, and the control circuit sends an ignition signal to the gate circuit to turn on the cyrisk. When the thyristor is turned on, the charge stored in the capacitor is discharged and a peak current is supplied.

〔Example〕

An embodiment of the inrush current supply circuit according to the present invention will be described below with reference to FIG.

The UPS is composed of an inverter 1 equipped with a switch 2, a bypass circuit 3 equipped with a switch 4, etc., and the inrush current supply circuit according to the present invention connects the inlet terminal USV of the commercial AC power supply of the UPS and the output terminal to the load. U, ,V
, is inserted between.

That is, the input terminal U and the output terminal U. A semiconductor switch 6 and a reactor 8 configured by connecting a diode and a thyristor in parallel are inserted in series between the input terminal V and the output terminal V. The semiconductor switch 6
The same semiconductor switch 7 is inserted.

Further, a transformer 5 is connected in parallel between the input terminals U and V, and charges capacitors 12 and 13 connected to the secondary side.

The positive terminal of the capacitor 12 is connected to the output side of the semiconductor switch 6 via the anode of a thyristor 14 including a gate circuit 21, and the negative terminal is connected to the output side of the semiconductor switch 7.

Similarly, the positive terminal of the capacitor 13 is connected to the output side of the semiconductor switch 7 via the anode of the thyristor 15 provided with the gate circuit 22, and the negative terminal is connected to the output side of the semiconductor switch 6.

Both terminals on the secondary side of the transformer 5 are connected to the capacitors 12 and 13 via diodes 16 and 17, respectively.
A resistor 20 connected to the positive terminal of the transformer 5 and the intermediate tap of the secondary coil of the transformer 5 is connected to the negative terminals of the capacitors 12 and 13 via diodes 18 and 19.

U of the inverter output circuit. A CT is provided on the coarse side, and sends a signal to the control circuit 11 via the overcurrent detector 23 when an overcurrent flows.

The control circuit 11 receives the signal and determines whether an overcurrent has occurred. Aika V. A signal is sent to the gate circuit 21 or 22.

The gate circuit 21 sends a firing signal to the thyristor 14 and the thyristors of the semiconductor switches 7 and 6, and the gate circuit 22 also sends a firing signal to the thyristor 14 and the thyristors of the semiconductor switches 7 and 6.
It has the function of sending an ignition signal to the thyristors 7 and 7.

Therefore, upon receiving the signal from the control circuit 11, it operates as shown in the time chart shown in FIG.

Figure 2 is U. This shows an example in which an inrush overcurrent occurs in a phase, and when the thyristor 14 is fired, the charge stored in the capacitor 12 is released, and an inrush current is supplied to the load. Here, the reactor 8 is inserted to determine the waveform of the peak current supplied from the capacitor.

The semiconductor switches 6 and 7 serve to prevent backflow from the inverter to the direct power supply during the inverter operation. The inverter 1 is locked due to the rush current flowing, and at the same time as the peak current is supplied from the capacitor 12 or 13 by firing the thyristor 14 or 15, the thyristors provided in the semiconductor switches 6 and 7 are also fired, Current is supplied to the load from the direct power source as shown in the time chart shown in FIG. This current supply is carried out for a period from when the inverter switch 2 is pulled out to when the bypass circuit switch 4 is turned on to start supplying power from the bypass circuit to the load.

Therefore, the peak value of the rush current generated by the parallel connection of a capacitor input type load can be supplied by the discharge current from the capacitor, and the remaining current can be supplied from the direct power supply via the semiconductor switches 6 and 7. Therefore, problems such as voltage drop and noise generation in the direct power supply system can be prevented.

〔Effect of the invention〕

As explained above, the UPS inrush current supply circuit according to the present invention can instantly detect the inrush current with a large peak value due to the parallel connection of a capacitor input type load, and fire the thyristor via the control circuit. The capacitor is discharged from the pre-charged charge, and the peak current is supplied to the load.

Therefore, since the direct power supply only needs to supply current other than the peak current, voltage fluctuations and noise disturbances in the direct power supply system can be reduced.

That is, by providing the inrush current supply circuit according to the present invention in a UPS with a bypass circuit, the inrush current associated with the load can be supplied regardless of the load, and there is also the effect of improving the supply stability of direct power supply.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of an inrush current supply circuit for a UPS according to the present invention, and FIG. 2 is a time chart for explaining the operation of the inrush current supply circuit. DESCRIPTION OF SYMBOLS 1... Inverter, 2.4... Switch, 3... Bypass circuit, 5... Transformer, 6.7... Semiconductor switch, 8... Reactor, 11... Control circuit, 12 .13... Capacitor, 14.15... Thyristor, 21.22... Gate circuit, 23... Overcurrent detector.

Claims (1)

[Scope of Claims] 1. An AC uninterruptible power supply device of a constant inverter power supply type configured by an inverter equipped with a switch in its output circuit and a bypass circuit equipped with a switch connected in parallel, the two A circuit consisting of a semiconductor switch in which a diode and a thyristor are connected in parallel between an input terminal and two output circuit terminals of an inverter, and a circuit in which the above semiconductor switch and a reactor are connected in series, and the primary side is the above 2. The two terminals on the secondary side are connected to the positive side of the capacitor through diodes, and a resistor is provided at the intermediate tap on the secondary side, and the two terminals are connected in parallel to the input sides of the semiconductor switches of the set. A transformer is connected to the negative side of one set of capacitors, and the positive sides of the two sets of capacitors are each connected to the output side of the above semiconductor switch via a thyristor, and the negative sides are connected to the output side of the semiconductor switch on the opposite side. The peak current is detected by the connected two sets of parallel circuits and an overcurrent detector installed in one line of the output circuit of the inverter, and upon receiving this detection signal, the two sets of parallel circuits connected to the positive terminal of the above capacitor are detected. An inrush current supply circuit for an AC uninterruptible power supply, comprising: a control circuit comprising a thyristor and two sets of gate circuits for selectively firing a thyristor and two sets of thyristors constituting the semiconductor switch;