JPH02155443A - Uninterruptible power source - Google Patents

Abstract

PURPOSE:To reduce the DC voltage width of an inverter by charging a floating battery by a DC forwardly converted from an AC and employing a sealing type lead storage battery unnecessary for uniformly charging as the floating battery of a circuit for generating the AC in an inverter circuit. CONSTITUTION:An AC power source AC is rectified by a rectifier 1, smoothed by a capacitor 2 to generate a DC to be forward converted. The generated DC is reversely converted by an inverter 3, the generated AC is supplied to a load 5, and a floating battery 4 is charged by the DC. As the floating battery 4, a lead storage battery unnecessary for uniformly charging is employed, and a suitable charging state is maintained only by floating charging. Thus, a variation in the DC voltage width of the inverter is reduced, and the necessary capacity of the inverter is decreased.

Description

[Detailed description of the invention] A. Industrial application field The present invention relates to an uninterruptible power supply.

B. Summary of the Invention The present invention reduces the required capacity of an inverter in an uninterruptible power supply having a storage battery that is charged in a floating manner by eliminating the need for equal charging of the storage battery.

C0 Conventional technology An uninterruptible power supply device reversely converts DC power obtained from a commercial power source through a forward converter into AC power using an inverter, and by installing a battery on the DC side of the inverter, it can be used even during a power outage of the commercial power source. The inverter uses DC power to provide uninterruptible output.

In such an uninterruptible power supply, a paste type lead acid battery is used as the storage battery, and a floating charging method in which the storage battery is always connected to the DC side is often adopted.

In conventional uninterruptible power supplies, storage batteries are constantly maintained in a charged state by floating charging, but when used for a long period of time, variations in voltage and electrolyte specific gravity occur between cells, causing changes in floating voltage. There is. For this reason, conventionally, once every few months, a larger charging current (
Equal charging is performed by charging at a voltage higher than the floating voltage (constant current charging method) or a voltage higher than the floating voltage (constant voltage charging method) to correct the balance of the voltage and specific gravity of the storage battery cells. Further, the forward converter is capable of outputting up to an equal charging voltage for charge control of the storage battery, and is equipped with a control means that normally lowers the output voltage to a floating charging voltage lower than the equal charging voltage.

D1 Problems to be Solved by the Invention In an uninterruptible power supply having a storage battery that performs equal charging and floating charging as described above, the eight rated inverter outputs are determined from the device output capacity, but the input voltage of the inverter ( DC input voltage) fluctuates from the uniform charging voltage of the storage battery to the voltage at the end of discharge of the storage battery. Therefore, the actual capacity of the inverter is the maximum input voltage (
The current is determined by the minimum input voltage (equal charging voltage).
The problem is that voltage fluctuations increase the required capacity of the inverter.

An object of the present invention is to provide an uninterruptible power supply that reduces the increase in required capacity of an inverter due to fluctuations in DC voltage.

81 Means and Effects for Solving the Problems In order to achieve the above object, the present invention provides an uninterruptible power supply device that obtains AC power from an inverter whose DC power source is a forward converter and a storage battery that is floatingly charged by the forward converter. The storage battery is a Nord-type lead-acid battery that eliminates the need for equal charging.This eliminates the need for high-voltage equal charging of the storage battery to reduce the DC voltage fluctuation range of the inverter, thereby reducing the required capacity of the inverter.

F. Embodiment diagram is a configuration diagram showing an embodiment of the present invention. The rectifier 1 rectifies AC power from a commercial power source to obtain DC power, and uses the DC power smoothed by a smoothing capacitor 2 as a DC input to an inverter 3 and as a floating charging power source to a storage battery 4.

The inverter 3 obtains AC power whose voltage and frequency are controlled and supplies it to a load 5 such as a computer.

Here, the storage battery 4 is a sealed lead-acid battery that does not require equal charging. Such a storage battery 4 is disclosed in, for example, Japanese Unexamined Patent Publication No. 5
It is disclosed in Japanese Patent No. 3-66542, and a proper charging state is maintained only by floating charging without performing equal charging.

According to the above-mentioned uninterruptible power supply using the sole type lead acid battery, it is possible to reduce the required capacity of the inverter 3 by eliminating the need for equal charging, which results in a higher voltage than floating charging, and in other words, to increase the actual capacity. For example, a sealed lead-acid battery has a floating charging voltage of 2.23V/cell, whereas a conventional lead-acid battery has an equal charging voltage of 2.3V/cell, making the minimum end-of-discharge voltage of both batteries the same. Therefore, there is a difference of 5%q in the input terminal fluctuation range of the inverter 3 between the two batteries, and the required capacity of the inverter 3 can be reduced by 5%.

In addition, by using the sealed lead-acid battery 4, the rectifier 1 eliminates the need for a switching function between floating charging voltage and equal charging voltage, and also eliminates the need for a voltage control function when the human-powered commercial power supply is stable. The voltage-one-frequency control on the side allows for the simplification of the control circuit and rectifier of the device.

G1 Effects of the Invention As described above, according to the present invention, since a floating charging type storage battery that does not require equal charging is used, the DC voltage fluctuation width of the inverter is reduced, thereby reducing the required capacity of the inverter. In other words, the actual capacity can be increased, and the charging means can be simplified, such as by replacing the forward converter with a rectifier.

1... rectifier, 5...Load.

inverter, 4...Storage battery, 2 people outside

[Brief explanation of the drawing]

The drawing is a configuration diagram showing an embodiment of the present invention.

Claims (1)

[Claims] (1) An uninterruptible power supply device that obtains AC power from an inverter that uses a forward converter and a storage battery that is floatingly charged by the forward converter as a DC power source, characterized in that the storage battery is a sealed lead-acid battery that eliminates the need for equal charging. Uninterruptible power supply.