JPH04312331A - Uninterruptible power supply - Google Patents

Abstract

PURPOSE:To enhance reliability of an uninterruptible power supply employing sealed lead batteries. CONSTITUTION:In an uninterruptible power supply comprising sealed lead batteries 6 connected thorugh a switch 5 to the joint of a rectifier 2 and an inverter 3, the switch 5 is normally turned OFF and periodically turned ON based on the output from a timer circuit 7 thus charging the sealed lead batteries 6. Consequently, the sealed lead batteries can be prevented from early degradation due to continuous charge operation, resulting in the enhancement of the reliability of uninterruptible power supply.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uninterruptible power supply, and more specifically, to improving the reliability of an uninterruptible power supply used as a backup power source for computers, communication equipment, and the like.

0002

2. Description of the Related Art As shown in the block diagram of FIG. 2, an uninterruptible power supply device normally supplies AC power from a commercial power supply 1 to computers, communication equipment, etc., either directly or via a rectifier and an inverter. In the event of a power outage, the DC power from the storage battery 6' is converted into AC power by the inverter 3 and supplied to the load 4, thereby preventing troubles in the load 4 due to a power outage.

[0003] The storage battery 6' in such an uninterruptible power supply is configured so that it is always kept in a fully charged state by floating charging with DC power obtained by rectifying AC power from a commercial power source 1 with a rectifier 2. backup is ensured in the event of a power outage.

[0004] On the other hand, in recent years, there has been an increasing demand for such uninterruptible power supplies to be maintenance-free, smaller, and lower in price, and storage batteries 6' are becoming more hermetically sealed and devices are becoming more densely packed. It's progressing.

That is, a sealed lead-acid battery 6 is used as the storage battery 6', and components including the sealed lead-acid battery 6 are being mounted in a housing at a high density.

By the way, the positive electrode plate used in the sealed lead-acid battery 6 is a grid made of a lead alloy filled with lead dioxide as an active material, and the surface of the grid is oxidized and corroded by charging. The volume expands, causing internal stress and reducing the strength of the lattice.

Therefore, when a sealed lead-acid battery is used under a floating state of charge, as in an uninterruptible power supply, the lattice will grow as charging continues, resulting in a short circuit with the negative strap, rupture of the battery case, and leakage. Liquid is more likely to be generated.

It is known that the growth increases as the amount of electricity charged increases, and that the amount of electricity charged in a floating charging state increases as the battery temperature increases. In the sealed lead-acid battery 6, since the battery temperature becomes high, the amount of charged electricity increases, which further increases the battery temperature.

[0009]

[Problems to be Solved by the Invention] In the above-mentioned uninterruptible power supply, the sealed lead-acid battery 6 deteriorates early, making it difficult to ensure high reliability over a long period of time. What is actually done for this purpose is to replace the sealed lead-acid battery 6 every two to three years, which has the problem of not being able to meet the requirement for maintenance-free operation.

0010

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a rectifier that rectifies AC power from a commercial power source, an inverter that converts the DC power from the rectifier into AC power, and a rectifier that rectifies AC power from a commercial power source. Consists of a sealed lead-acid battery connected via a switch from the connection point with the inverter.
Normally, the switch is turned off to supply power to the load from the commercial power supply directly or via an inverter, and the switch is turned on periodically to charge the sealed lead acid battery, and in the event of a power outage, the sealed lead acid battery is It is characterized in that the inverter converts DC power from the lead-acid battery into AC power to continue supplying power to the load.

[0011]

[Function] As described above, the present invention eliminates the need for a sealed lead-acid battery to be kept on standby in a floating charging state all the time, and can prevent deterioration of the sealed lead-acid battery due to growth of the lattice.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an uninterruptible power supply according to the present invention, in which parts having the same functions as those in FIG.

The feature of the present invention is that the rectifier 2 and the inverter 3
A sealed lead-acid battery 6 is connected through a switch 5 from the connection point with the switch 5, and a timer circuit 7 is provided to periodically turn on the switch 5. A signal sent from the timer circuit 7 normally turns on the switch. 5 is turned off, and power is supplied to the load 4 from the commercial power source 1 via the direct line 10 or via the rectifier 2 and inverter 3.

When the commercial power supply 1 is out of power, the diode 8 connected in parallel with the switch 5 becomes conductive, so that the DC power from the sealed lead-acid battery 6 is converted to AC power by the inverter 3, and the power is supplied to the load. 4 can be continued.

Further, when the timer circuit 7 operates and the first set time elapses, a signal is sent from the timer circuit 7 to turn on the switch 5, and the switch 5 is turned on and the sealed lead acid battery 6 is turned on. Charging is performed. This charging continues for a second set time of the timer circuit 7,
When the second set time has elapsed, a signal to turn off the switch 5 is sent from the timer circuit 7, and the switch 5 is turned off to stop charging the sealed lead acid battery 6.

Each of the set times is determined by the self-discharge characteristics of the sealed lead-acid battery 6, and the sealed lead-acid battery 6 has a 90% discharge rate in order to ensure the reliability of the uninterruptible power supply.
It is necessary to maintain the above capacity. Normally, the above capacity can be maintained by charging for about 24 hours once a month, so it is appropriate to set the first setting time to one month and the second setting time to 24 hours. However, it goes without saying that it can be changed depending on the type of sealed lead acid battery 6.

In the present invention, in the case of a constant commercial power supply system using the direct feed line 10, the rectifier 2 may be operated or stopped instead of turning the switch 5 on and off. Note that the present invention can also be applied to a constant inverter power supply system in which the direct feed line 10 is used as a backup in case of a failure of the inverter 3, but in this case, it can be realized only by turning the switch 5 on and off.

[0018]

As described above, according to the present invention, the sealed lead acid battery 6 is kept open at all times and is periodically charged by the timer circuit 7. early deterioration of the uninterruptible power supply can be prevented, and the reliability of the uninterruptible power supply can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an uninterruptible power supply according to the present invention.

FIG. 2 is a block diagram of a conventional uninterruptible power supply.

[Explanation of symbols]

1 Commercial power supply 2 Rectifier 3 Inverter 4 Load 5 Switch 6 Sealed lead acid battery 7 Timer circuit

Claims (2)

[Claims] 1. A rectifier that rectifies AC power from a commercial power source, an inverter that converts the DC power from the rectifier into AC power, and a sealed type connected via a switch from a connection point between the rectifier and the inverter. The switch is normally turned off and power is supplied to the load from the commercial power source directly or via a rectifier and inverter, and the switch is turned on periodically to supply power to the load. An uninterruptible power supply device characterized in that the DC power from the sealed lead-acid battery is converted into AC power by the inverter during a power outage to continue power supply to a load. 2. The switch is operated by a timer circuit that sends a signal that turns on when a first set time elapses and turns off when a second set time elapses after being turned on. The uninterruptible power supply according to paragraph 1.