JPH04322135A - Uniterruptible power supply - Google Patents

Abstract

PURPOSE:To enhance reliability and performance of an uninterruptible power supply employing enclosed lead battery. CONSTITUTION:The uninterruptible power supply comprises an enclosed lead battery 6 connected through a first switch 5-1 with the joint of a rectifier 2 and an inverter 3 and a charger 9 for feeding the enclosed lead battery 6 with power from a commercial power supply 1 through a second switch 5-2. The second switch 5-2 is normally turned OFF and a control signal generator 7 monitors the open circuit voltage of the enclosed lead battery 6. When the open circuit voltage drops below a predetermined level, the second switch 5-2 is turned OFF to charge the enclosed lead battery 6 and after detection of closed circuit voltage, the second switch 5-2 is turned OFF. Consequently, early deterioration of the enclosed lead battery 6 due to sustained charging operation can be prevented resulting in enhancement of the reliability and performance of uninterruptible power supply.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an uninterruptible power supply, and more specifically, to improving the reliability and performance of an uninterruptible power supply used as a backup power source for computers, communication equipment, etc. be.

0002

2. Description of the Related Art A conventional uninterruptible power supply, as shown in FIG. By converting the DC power from the AC power source into AC power using the inverter 3 and supplying the AC power to the load 4, problems with the load 4 due to power outages can be prevented.

[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.

[0007] Therefore, when used in a floating charging state 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. .

[0008] Generally, the growth increases as the amount of charged electricity increases, but since the battery temperature becomes high in such a densely packed sealed lead-acid battery 6, the amount of charged electricity increases and the battery temperature further rises. I will let you do it.

For this reason, some batteries are equipped with a temperature compensation circuit that reduces the floating charge voltage as the temperature rises, but what is actually done to improve the reliability of this is the sealed lead-acid battery. 6 is replaced every 2 to 3 years.

0010

[Problems to be Solved by the Invention] Conventional uninterruptible power supplies as described above have a problem in that high reliability cannot be ensured over a long period of time.

[0011]

[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. It consists of a sealed lead-acid battery connected via a first switch from a connection point with an inverter, and a charger that supplies charging power from a commercial power source to the sealed lead-acid battery via a second switch, and at least A control signal generator having a function of monitoring the commercial power supply voltage and a function of monitoring the closed circuit voltage of the sealed lead-acid battery is provided, and the first and second switches are always turned off and the control signal generator is connected to the commercial power supply. Power is supplied to the load from the power supply directly or via a rectifier and an inverter, and in the event of a power outage, the first switch is turned on and the DC power from the sealed lead acid battery is converted to AC power by the inverter, and the power is supplied to the load. The power supply is continued, and after the power is restored, the power supply is switched to the commercial power supply, and the second switch is turned on to charge the sealed lead-acid battery via the charger. This feature is characterized by turning off the second switch.

0012

[Function] With the above structure, the sealed lead-acid battery does not stand by in a floating state of charge, and the growth of the lattice can be reduced.

[0013]

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 charger that connects a sealed lead acid battery 6 from a connection point with a first switch 5-1 and charges the sealed lead acid battery 6 from a commercial power source 1 through a second switch 5-2. A control signal generator 7 is provided which has a function of monitoring the voltage of the commercial power supply 1 and a function of monitoring the open circuit voltage and closed circuit voltage of the sealed lead acid battery 6. The first and second switches 5-1 and 5-2 are turned off by a signal sent from the commercial power supply 1 through the direct line 10, and power is supplied to the load 4 from the commercial power supply 1 through the direct transmission line 10. is monitored for its open circuit voltage.

When the control signal generator 7 detects a power outage in the commercial power supply 1, the control signal generator 7 sends a signal to turn on the first switch 5-1, and the sealed lead-acid battery is turned on. The DC power from 6 is converted into AC power by the inverter 3 to continue supplying power to the load 4.

Further, when it is detected that the open circuit voltage of the sealed lead-acid battery 6 has decreased to 102 V (12.75 V per cell) or less, the control signal generator 7 sends a signal to the second switch 5-2. A signal is sent to turn on the battery charger 9, and the sealed lead acid battery 6 is charged by the charger 9. At this time, the closed circuit voltage of the sealed lead acid battery 6 is monitored.

Next, when the control signal generator 7 detects the restoration of the commercial power supply 1, the first switch 5-
1 is turned off and the second switch 5-2 is turned on, the commercial power supply 1 starts supplying power to the load 4, and the charger 9 starts charging the sealed lead-acid battery 6. When it is detected that the closed circuit voltage has reached a predetermined value, the control signal generator 7 sends a signal to the second switch 5-2.
A signal is sent to turn off the battery, and monitoring of the open circuit voltage of the sealed lead-acid battery 6 is restarted. From this point on, the control signal generator 7 then increases the open circuit voltage to 102V (12V per cell).
．． The time (open circuit voltage) until it drops to 75 V) or less is monitored, and the time to turn on the second switch 5-2 is calculated based on this open circuit time, and when the open circuit voltage decreases, the closed type After the lead acid battery 6 is charged, the second
It also has a function to turn off the switch 5-2. This can prevent charging of the sealed lead acid battery 6 from continuing longer than necessary.

Now, the uninterruptible power supply A of the present invention as described above
When we set the conventional uninterruptible power supply B shown in Fig. 3 in a constant temperature room at 40°C, and conducted a life performance test to investigate the 10-minute rate capacity of the sealed lead-acid battery 6 every 6 months, the following results were obtained. 1
The following results were obtained.

[0019]

[Table 1]

From Table 1, it can be seen that the sealed lead-acid battery 6 of the uninterruptible power supply A according to the present invention
times, approximately 12Ah is charged per time, and a total of approximately 4
00Ah charging, whereas conventional uninterruptible power supply B
It was found that an average current of about 30 mA always flows through the sealed lead-acid battery 6, and the life span was reached after 30 months after being charged for a total of about 650 Ah. This shows that the uninterruptible power supply A of the present invention has high reliability over a long period of time. was found to be obtained.

Next, another embodiment of the present invention will be explained with reference to FIG. In the embodiment shown in FIG. 2, an indicator 8 is added to the control signal generator 7, and when the open circuit time from the start of open circuit voltage measurement to the time when the open circuit voltage decreases to a predetermined value is shorter than a predetermined time, the sealed type This display indicates that the lead-acid battery 6 should be replaced, and the time for replacing the sealed lead-acid battery 6 can be displayed well in advance.

That is, at the end of its life, the sealed lead-acid battery 6 increases its self-discharge amount and shortens its open circuit time, which greatly contributes to improving the reliability of the uninterruptible power supply.

Furthermore, in this embodiment, the control signal generator 7
It is also possible to provide a function to monitor the internal resistance of the sealed lead-acid battery 6, and to display on the display 8 that the sealed lead-acid battery 6 should be replaced when the internal resistance exceeds a predetermined value.

Furthermore, the control signal generator 7 is provided with a function of monitoring the historical temperature of the sealed lead-acid battery 6, and displays a message to replace the sealed lead-acid battery 6 when the temperature exceeds a predetermined value for a predetermined period of time. It can also be displayed on the device 8.

[0025] The replacement timing of the sealed lead-acid battery 6 is calculated by appropriately combining the historical temperature monitor value, the open circuit time monitor value, the internal resistance monitor value, and the open circuit voltage monitor value, and calculates the result of the calculation. It is also possible to do this by

The above-mentioned embodiment has been explained using a constant commercial power supply system using the direct feed line 10; however, the direct feed line 10
It goes without saying that a constant inverter power supply system that uses the inverter 3 as a backup in case of a failure can also be applied.

[0027]

Effects of the Invention As described in detail in the embodiments, the uninterruptible power supply of the present invention keeps the sealed lead-acid battery on standby in an open state at all times, monitors its open circuit voltage, and prevents the open circuit voltage from decreasing below a predetermined value. When this occurs, the switch is turned on for a time calculated based on the open circuit time to charge the sealed lead acid battery, thereby preventing premature deterioration of the sealed lead acid battery 6 due to continued charging. Can be done.

[0028] In addition, the control signal generator is equipped with an open circuit voltage monitoring function, an internal resistance monitoring function, a historical temperature monitoring function, and a closed circuit voltage monitoring function of the sealed lead-acid battery, either singly or in combination. By displaying the time to replace the lead-acid battery, it is possible to improve the reliability of the uninterruptible power supply.

[Brief explanation of drawings]

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

FIG. 2 is a block diagram of an uninterruptible power supply according to the present invention.

FIG. 3 is a block diagram of a conventional uninterruptible power supply.

[Explanation of symbols]

1 Commercial power supply 2 Rectifier 3 Inverter 4 Load 5-1 First switch 5-2 Second switch 6 Sealed lead acid battery 7 Control signal generator 8. Display 9 Charger

Claims (6)

[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 first switch connected to the connection point between the rectifier and the inverter. a sealed lead-acid battery; and a charger that supplies charging power from a commercial power source to the sealed lead-acid battery via a second switch, the charger having at least a function of monitoring the commercial power supply voltage, and a charger that supplies charging power to the sealed lead-acid battery from a commercial power supply. A control signal generator having a function of monitoring the closed circuit voltage of the circuit is provided, and the first and second switches are always turned off, and power is supplied to the load from the commercial power source directly or via a rectifier and an inverter. , during a power outage, the first
The switch is turned on, and the inverter converts the DC power from the sealed lead-acid battery into AC power to continue power supply to the load. After power is restored, the power supply is switched to the commercial power supply, and the second An uninterruptible power supply device characterized in that a switch is turned on to charge the sealed lead-acid battery via a charger, a closed circuit voltage of the battery is detected, and the second switch is turned off. Claim 2: The control signal generator is provided with a function of monitoring the open circuit voltage of the sealed lead-acid battery when the second switch is turned off, and when the open circuit voltage drops below a predetermined value, the second switch is turned on. The uninterruptible power supply according to claim 1, characterized in that: 3. The control signal generator is provided with a function of monitoring an open circuit time from the start of open circuit voltage measurement to the time when the open circuit voltage decreases to a predetermined value, and the second switch is turned on based on this open circuit time. 2. The uninterruptible power supply according to claim 1, wherein time is calculated. 4. The uninterruptible power supply according to claim 1, wherein the control signal generator is provided with a function of monitoring the internal resistance of the sealed lead acid battery. 5. The uninterruptible power supply according to claim 1, wherein the control signal generator is provided with a function of monitoring the historical temperature of the sealed lead acid battery. 6. The control signal generator is provided with an indicator, and when any one of the open circuit voltage monitor value, internal resistance monitor value, historical temperature monitor value, and open circuit time monitor value reaches a predetermined value, or 2. The uninterruptible power supply device according to claim 1, wherein each monitor value is combined and calculated, and the time to replace the sealed lead acid battery is displayed on the display according to the calculation result.