JPH0318233A - Uninterruptible power supply device - Google Patents

Abstract

PURPOSE:To ensure an uninterruptible power supply by providing a plurality of storage batteries to be connected in parallel at the time of service interruption and a plurality of charging circuits for charging respective storage batteries separately, by connecting one of the storage batteries directly with the load side, and by inserting and connecting a relay contact to be ON-driven at the time of service interruption between the output ends of the other storage batteries and the load side. CONSTITUTION:An apparatus is provided with two storage batteries 21, 22 and two chargers 11, 12, and the storage battery 21 is directly connected with a dropper circuit 5 while a relay contact R1 is inserted in and connected with the storage battery 22. The relay contact R of the relay Ry is a normally closed type and returns to ON, when the relay Ry is turned OFF at the time of service interruption, but the contact is OFF usually. When a commercial power supply is sound, a load 3 is supplied wtih a stable DC power by a DC power circuit 4. When the electricity is cut OFF, power is supplied from the storage battery 21 to the load 3 via the dropper circuit 5 without momentary break. After that, the contact R1 is turned ON so that the storage batteries 21, 22 supply the load 3 with power in a parallel-connected state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an uninterruptible power supply that supplies power to a load from a plurality of normally charged storage batteries during a power outage.

[Conventional technology] DC uninterruptible power supplies (with backup function) are increasingly being introduced for disaster prevention and other equipment, and AC uninterruptible power supplies are increasingly being introduced for computer equipment such as personal computers. As a circuit for charging Ni-Cd storage batteries etc. used in If you leave it in a charged state, even if the power supply from the commercial power source is cut off at any time,
A predetermined amount of power can be supplied using the power of a storage battery.

Here, if the output capacity of the power supply device is relatively large,
If the power outage compensation time (backup time +8!) is long,
A storage battery with a large capacity is required, but since commercially available storage batteries have a limited capacity, storage batteries may have to be connected in parallel. For example, Ni-Cd
In the case of storage batteries, the maximum capacity of currently commercially available products is 4Ah (ampere hour), but if 6Ah is required, 3Ah
Storage battery 1 - 2 ? Must be used in parallel.

FIG. 4 shows a conventional example, in which one charger 1 is provided with a plurality of storage batteries 2 each having a plurality of cells arranged in an elliptical manner.
．． 2■...This is a case where 2n are connected in parallel and charged. When two or more sets of storage batteries 2,... are charged in parallel using the constant current charging method, the charging current flowing to each storage battery 2,...
1 to I n are determined by the internal impedance of each storage battery 21 . Therefore, if the internal impedances of the storage batteries 21 are the same, they will be charged equally, but since they usually vary, the charging currents I1 to I
n will also vary. Therefore, even if a plurality of storage batteries 21, . As a result, in order to charge a plurality of storage batteries 21 with constant current, a charger must be provided for each battery.

FIG. 5 shows a conventional example of a DC uninterruptible power supply circuit using two sets of storage batteries 21 and 22.

When the commercial power supply is healthy, are storage batteries 2, 2 ■ chargers? 1
．． 1), the batteries are charged in a fully charged state at all times, and a stable DC power is supplied to the load 3 by the DC power supply circuit 4. When a power outage occurs, the power supply from the DC power supply circuit 4 is interrupted, and the power from the storage battery 2 is used to supply power to the load 3 via the diodes D, D2 and the dropper circuit 5. By doing so, the power supply to the load 3 can be uninterrupted without interruption. still,
The diodes D, D2 are diodes for preventing backflow so that each charging current does not flow into the other storage battery 2.

[Problem to be solved by the invention] In the conventional example shown in FIG.
Since r and D2 are used, the voltage at point a in the figure is b
The voltage will be lower than the voltage at the point. That is, due to the characteristics of the diode, a forward voltage drop occurs. In the case of silicon-based diodes, the drop voltage is about 0.7V<. This voltage drop causes the following problems.

■ Considering the input voltage range of the load 3, there is a voltage drop 34, so it is necessary to compensate for the drop by increasing the number of cells in the storage battery 2.

■ If the output current is large, the diode D. The power loss consumed by D2 becomes large.

(2) Additionally, it is necessary to use a large-capacity diode, and fins for heat dissipation are required, which is uneconomical.

The present invention has been provided in view of the above-mentioned points, and when a plurality of storage batteries are used, power is supplied to the load without interruption, and there is no voltage drop between the storage batteries and the output. The purpose is to provide a relatively low-cost uninterruptible power supply.

[Means for Solving the Problems] The present invention includes a plurality of storage batteries connected in parallel during a power outage,
It has a plurality of charging circuits that charge each of these storage batteries independently, and one of the plurality of storage batteries is directly connected to the load side, and a circuit between the output terminal of the remaining storage batteries and the load side is turned on in the event of a power outage. This is characterized by the fact that a relay contact is inserted and connected.

? Effect] With the above configuration, in the event of a power outage, power is supplied to the load through the relay contact without causing a voltage drop on the load side.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure shows a specific circuit diagram, and includes two storage batteries 2, 2 and 2.
One storage battery 2 is directly connected to the dropper circuit 5, and the other storage battery 22 has a relay contact R inserted therein. Relay RS1 is connected to the commercial power supply side, and the relay contact RI of this relay R is a normally closed type. During a power outage, relay Ry turns off, returns to turn on, and normally turns off. It has become.

When the commercial power supply is healthy, storage batteries 2 and 22 are connected to charger 1+.
, 1■, respectively, and are always fully charged. At this time, since the relay contact R1 of the relay RV is in an open state, each charging current does not flow into the other storage battery 2. In addition, the load 3 is connected to the DC power supply circuit 4 by 5 6 ? Provides stable DC power.

When a power outage occurs, at that moment, power is supplied from the storage battery 21 to the load 3 via the dropper circuit 5 without momentary interruption. After that, relay contact R1 is turned on, so storage battery 2. ,2■
are connected in parallel and supply power to the load 3. Therefore, power can be supplied to the load 3 completely without interruption.

FIG. 2 shows an embodiment in which there are n storage batteries 2, and in this case, only the storage batteries 21 are directly connected to the dropper circuit 5,
The other storage battery 2■... is the relay contact R1 of the relay Ry.
are connected. In this embodiment, as in the case of FIG. 1, power can be supplied without interruption, and moreover, during charging, the charging current can be prevented from flowing into the battery by the relay contact R for the charging current.

FIG. 3 shows still another embodiment, and in the previous embodiment, a DC uninterruptible power supply was used, but this shows an AC uninterruptible power supply. The difference from the previous embodiment is that an inverter circuit 7 is inserted before the load 3. At this time, when the commercial power source is healthy, the rectifier circuit 6 converts the commercial power source into direct current and supplies power. At the same time, each of the storage batteries 21 . . . is being charged by the charger 1 . When a power outage occurs, the DC power of the storage batteries 2B is converted into AC power by the inverter circuit 7 and supplied to the load 3 in the same process as in the previous embodiment.

[Effects of the Invention] As described above, the present invention includes a plurality of storage batteries that are connected in parallel during a power outage, and a plurality of charging circuits that independently charge the storage batteries, and one of the plurality of storage batteries is It is directly connected to the load side, and a relay contact that is turned on during a power outage is inserted between the output end of the remaining storage battery and the load side, so in the event of a power outage, the voltage is transferred to the load side via the relay contact. It is designed to supply power to the load without causing a voltage drop, and it can supply power to the load without interruption, and there is almost no voltage drop between the storage battery and the load. Since the circuit configuration is simple, the circuit can be assembled at relatively low cost, and since the storage batteries are charged individually, there is an effect that there is little variation in the charging state of each storage battery.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram of another embodiment same as above, Fig. 3 is a circuit diagram of still another embodiment same as above, and Fig. 4 is a circuit diagram of a conventional example. , FIG. 5 is a circuit diagram of another conventional example. 1 is a charger, 2 is a storage battery, 3 is a load, and R1 is a relay contact.

Claims (1)

[Claims] (1) In an uninterruptible power supply system that normally supplies DC power generated from a commercial power supply to the load, and during a power outage, supplies power to the load from a storage battery that has been charged during normal times, when connected in parallel during a power outage. It has a plurality of storage batteries and a plurality of charging circuits that charge each of the storage batteries independently.One of the plurality of storage batteries is directly connected to the load side, and the output end of the remaining storage battery is connected to the load side. An uninterruptible power supply device characterized in that a relay contact that is turned on during a power outage is inserted and connected in between.