JP3751941B2 - Uninterruptible power supply system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an uninterruptible power supply system that supplies backup power in the event of a power failure.
[0002]
[Prior art]
In recent years, large-scale regional power outages have been drastically reduced due to the improvement of the power supply environment in Japan, but there are many cases where large power facilities such as large air conditioners and refrigerators are juxtaposed in store systems. The frequency of occurrences of power outages in stores due to overcapacity or instantaneous power outages due to breakers in each power system is not rare. In addition, the frequency is increasing in the unstable field of power supply environments such as overseas.
[0003]
Thus, in order to ensure stable operation in a store system or the like, it is indispensable to install an uninterruptible power supply system. Moreover, since the storage battery used for an uninterruptible power supply system has a lifetime, it is important to perform a lifetime determination test and know an appropriate replacement time based on the test result.
[0004]
As a conventional method for determining the life of a storage battery, for example, there are methods described in JP-A-2-55536 and JP-A-2000-21215.
[0005]
The method disclosed in Japanese Patent Laid-Open No. 2-55536 is to perform a battery life determination test by discharging a backup battery at regular intervals (see Patent Document 1).
[0006]
Japanese Patent Laid-Open No. 2000-21215 starts a test operation every predetermined period, and determines the life based on the voltage value of the battery after a specified time during the test operation (see Patent Document 2). .
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2-55536 (second page, lower left column, line 8 to same page, lower right column, line 12, FIG. 1)
[Patent Document 2]
JP 2000-21215 (paragraphs 0019 to 0022, FIGS. 1 and 4)
[0008]
[Problems to be solved by the invention]
However, in the conventional life determination method, since the life determination test is performed at regular intervals, not only the capacity of the battery is reduced, but also switching to the backup power source is delayed if a power failure occurs during the life determination test. There was a problem that the reliability of backup decreased.
[0009]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an uninterruptible power supply system capable of suppressing the number of life determination tests and improving the reliability of power backup.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an uninterruptible power supply system for supplying power to a backup storage battery in the event of a power failure and performing power backup, a means for detecting a power failure, a means for discharging the current of the storage battery, Connection means for turning on / off the connection between the discharge means and the storage battery, and resetting when a power failure is detected or a preset specified count value is exceeded, or the backup operation of the storage battery is completed, or the discharge A timing means for starting a counting operation when the connection between the means and the storage battery is turned off, a measuring means for measuring the current and voltage of the storage battery, and a battery voltage value after a predetermined time from the start of discharge measured by the measuring means Is calculated with respect to the expected value of the battery voltage after the predetermined time when discharged at the current value measured by the measuring means, And means for performing life determination of the battery by the calculation result to determine meets criteria battery voltage with respect to the expected value, the lifetime determination means, the count value of said counting means of said battery When a power failure is detected by the power failure detection means while the charging completion time is exceeded and the specified count value is not exceeded, the life of the storage battery is determined, and further, the count value of the time measuring means is the value of the storage battery. When the charge completion time is exceeded and the specified count value is exceeded, the connection means turns on the connection between the storage battery and the discharge means, and the life determination means then determines the life of the storage battery. It is characterized by.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of an uninterruptible power supply system according to the present invention. In FIG. 1, reference numeral 1 denotes a backup storage battery used during a power failure, and reference numeral 11 denotes a charging circuit that charges the storage battery 1. The charging circuit 11 charges the storage battery 1 in a steady state at the time of uninterruptible power.
[0012]
2 is a current detection circuit for detecting the current of the storage battery 1, and 3 is a voltage detection circuit for detecting the voltage of the storage battery 1. The calculation unit 4 calculates the life of the storage battery 1 based on the current value detected by the current detection circuit 2 and the voltage value detected by the voltage detection circuit 3, and updates the predicted life data of the storage battery 1. The life determination unit 5 determines the life of the storage battery 1 based on the calculation result of the calculation unit 4 and gives an instruction to replace the storage battery 1. Calculations and determination methods by the calculation unit 4 and the life determination unit 5 will be described later.
[0013]
Also, 6 is a changeover switch, 7 is a power failure detection circuit for detecting a power failure, 8 is a timer, 9 is a power supply circuit that converts the power supply of the storage battery 1 to a predetermined voltage value at the time of a power failure, and supplies it to a load as a backup power source. Is a discharge circuit which performs resistance discharge and is used for a life determination test of the storage battery 1. The change-over switch 6 is switched according to the output of the power failure detection circuit 7 and the state of the timer 8, and turns off the connection between the storage battery 1, the power supply circuit 9, and the discharge circuit 10 in a steady state at the time of no power failure.
[0014]
When a power failure is detected by the power failure detection circuit 7, the changeover switch 6 connects the storage battery 1 and the power supply circuit 9 via the current detection circuit 2 and backs up the power supply from the storage battery 1 from the power supply circuit 9. The timer 8 is used for controlling the timing of the life determination test. For example, the timer 8 is reset when a power failure occurs, and starts counting when the storage battery 1 starts to be charged, that is, when the backup operation of the power supply circuit 9 is completed. The timer 8 is reset when a preset time is counted, and is set after a certain time.
[0015]
Timer 8 is set to count up when a set time (specified count value) equal to or greater than the charging completion time of storage battery 1 is set according to the power supply environment of the system, and power failure occurs until timer 8 counts the specified count value. Only when the detection is not performed, the changeover switch 6 connects the storage battery 1 and the discharge circuit 10. Therefore, only when the power failure is not detected for a certain period of time after the power failure is restored, the storage battery 1 and the discharge circuit 10 are connected and the life judgment test of the storage battery 1 is performed.
[0016]
On the other hand, when a power failure is detected before the timer 8 counts the specified count value, the changeover switch 6 does not connect the storage battery 1 and the discharge circuit 10 and does not perform a life determination test of the storage battery 1.
[0017]
Next, the operation of this embodiment will be described in detail with reference to the timing chart of FIG. FIG. 2A shows a power failure detection of the power failure detection circuit 7, and FIG. 2B shows charging and stopping of the storage battery 1 by the charging circuit 11. First, when a power failure is detected by the power failure detection circuit 7 as shown in FIG. 2A at time t1, charging of the storage battery 1 is stopped as shown in FIG. 2B, and charging is not performed during the power failure period. When the power failure ends at time t2, the storage battery 1 is charged.
[0018]
Further, when a power failure is detected by the power failure detection circuit 7 at time t1, the storage battery 1 and the power circuit 9 are connected by the changeover switch 6, and the power source is backed up from the power circuit 9 as shown in FIG. . When the power failure occurs, the current of the storage battery 1 is detected by the current detection circuit 2, the voltage of the storage battery 1 is detected by the voltage detection circuit 3, and the calculation unit 4 performs the calculation of the storage battery 1 based on the detection result. Update lifetime data as shown in f).
[0019]
As a method for determining the life, for example, the discharge current Idc during backup is measured by the current detection circuit 2, and the battery voltage Vbt after a predetermined time set in advance from the start of backup (start of discharge) is measured by the voltage detection circuit 3. This specified time is measured using a timer (not shown). The expected value of the battery voltage Vbt after discharging for a specified time with the discharge current Idc is determined by the battery characteristic data, and this information is input to the calculation unit 4 in advance.
[0020]
The calculator 4 calculates how much the measured battery voltage Vbt is relative to the expected value. In addition, a criterion for determining the battery voltage Vbt relative to the expected value is determined in advance (for example, 50% or less as the lifetime), and the lifetime determining unit 5 determines the battery lifetime based on this criterion. If the battery voltage Vbt is 50% or less of the criterion, it is determined that the storage battery 1 has reached the end of its life, and a notification to that effect is given to the user to prompt replacement of the storage battery 1. When the power failure is restored at time t2, the changeover switch 6 disconnects the connection between the storage battery 1 and the power supply circuit 9, and supplies power from the commercial power supply as shown in FIG. 2 (d) (AC drive).
[0021]
On the other hand, the timer 8 is reset when a power failure is detected at time t1, as shown in FIG. 2E, and starts counting when the backup operation of the power supply circuit 9 ends at time t2. The specified count value of the timer 8 is set to be equal to or longer than the charging completion time of the storage battery 1 as described above. When the timer 8 counts up the specified count value at time t3 as shown in FIG. Is reset. Further, as shown in FIG. 2C , at the same time, the storage battery 1 and the discharge circuit 10 are connected by the changeover switch 6.
[0022]
That is, since the changeover switch 6 connects the storage battery 1 and the discharge circuit 10 only when the power failure detection is not performed until the timer 8 counts the specified count value as described above, FIG. The storage battery 1 and the discharge circuit 10 are connected as shown in FIG. The changeover switch 6 keeps the connection between the storage battery 1 and the power supply circuit 9 disconnected.
[0023]
When the storage battery 1 and the discharge circuit 10 are connected, resistance discharge is performed by the discharge circuit 10, the current of the storage battery 1 is detected by the current detection circuit 2, and the voltage of the storage battery 1 is detected by the voltage detection circuit 3. Is done. The arithmetic unit 4 calculates the life of the storage battery 1 based on the detected current value and voltage value, and the life determination unit 5 determines the life of the storage battery 1 based on the life criterion. The life judgment method in this case is exactly the same as in the case of a power failure.
[0024]
Next, the timer 8 is reset for a certain period as shown in FIG. 2 (e), and starts counting at time t4. Next, when a power failure is detected by the power failure detection circuit 7 at time t5, charging of the storage battery 1 is similarly stopped. Moreover, the storage battery 1 and the power supply circuit 9 are connected by the changeover switch 6, and the power supply is backed up from the power supply circuit 9 as shown in FIG.
[0025]
Further, when the occurrence of a power failure at time t5 is detected, the timer 8 is reset as shown in FIG. 2E. In this case, the power failure occurs before the timer 8 counts the specified count value from the start of the count operation at time t4. Therefore, the changeover switch 6 does not connect the storage battery 1 and the discharge circuit 10 as shown in FIG. Therefore, the life of the storage battery 1 is not calculated by the calculation unit 4 and the life data is not updated as shown in FIG.
[0026]
As described above, in the present embodiment, the life judgment test of the storage battery 1 is performed when a power failure occurs during system operation, and only when the power failure is not detected until the set time longer than the charging completion time of the storage battery 1 after the power failure is restored. Since the life determination test is performed, the number of life determination tests by resistance discharge can be minimized.
[0027]
Therefore, in the case where the life is determined by the discharge resistance at regular intervals unconditionally, it may be possible to impair the reliability of the power backup, but in this embodiment, the number of life determination tests is minimized. Therefore, the capacity of the storage battery 1 is not wasted, and the possibility of delay in switching to the backup power source when a power failure occurs is reduced, and the reliability of power backup can be improved.
[0028]
In particular, in a field where the power supply environment is bad and frequent power outages occur, the life test can be performed during backup operation as described above, and the number of tests with periodic discharge resistance can be reduced, reducing reliability. It is effective because a life test can be performed.
[0029]
In this embodiment, the life determination at the time of a power failure depends on the life determination time, and in the case of a short power failure, the life determination may not be performed. When the life determination method as described above is used, for a power failure that recovers in a short time (for example, 2 to 3 seconds), the discharge time is short and accurate measurement and life calculation are not possible. If the life can be determined in a short time, the life can be determined even in the event of an instantaneous power failure.
[0030]
Here, when the life of the storage battery 1 is determined, the battery voltage after the specified time is detected using the timer as described above, but when the power failure is restored before the specified time is measured, the battery voltage is measured. I can't. It should be noted that a short power outage that cannot be determined for the life is considered to have no effect on the system or on the life determination due to the next discharge resistance because the storage battery 1 is consumed little and recovers immediately.
[0031]
【The invention's effect】
As described above, according to the present invention, by performing a life determination test of a storage battery at the time of a power failure, by performing a life determination test only when there is no power outage for a certain period of time beyond the charging completion time of the storage battery from power failure recovery, The life determination test of the storage battery can be suppressed to the minimum necessary, and the reliability of the power backup can be improved as compared with the conventional case.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an uninterruptible power supply system of the present invention.
FIG. 2 is a timing chart showing the operation of the embodiment of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Storage battery 2 Current detection circuit 3 Voltage detection circuit 4 Operation part 5 Life judgment part 6 Changeover switch 7 Power failure detection circuit 8 Timer 9 Power supply circuit 10 Discharge circuit 11 Charging circuit

Claims (3)

In an uninterruptible power supply system that performs power backup by supplying power to the backup storage battery when a power failure occurs,
A means of detecting a power outage;
Means for discharging the current of the storage battery;
Connection means for turning on / off the connection between the discharge means and the storage battery;
It is reset when a power failure is detected, or when a preset count value set in advance is exceeded, and the backup operation of the storage battery is completed, or the count operation is started when the connection between the discharge means and the storage battery is turned off. Means ,
Measuring means for measuring the current and voltage of the storage battery;
What is the battery voltage value after a predetermined time from the start of discharge measured by the measuring means with respect to the expected value of the battery voltage after the predetermined time when discharged at the current value measured by the measuring means? Means for determining the life of the storage battery by determining whether the calculation result satisfies a criterion for determining a battery voltage with respect to the expected value ,
The life determination unit is configured such that when a power failure is detected by the power failure detection unit while the count value of the time measuring unit exceeds the charging completion time of the storage battery and does not exceed the specified count value, the life of the storage battery is determined. Make a decision,
Further, when the count value of the time measuring means exceeds the charging completion time of the storage battery and exceeds the specified count value, the connection means turns on the connection between the storage battery and the discharge means, and the life determination means In this case, an uninterruptible power supply system that determines the life of the storage battery . 2. The uninterruptible power supply system according to claim 1 , wherein the life determination unit does not perform a life determination when a short power failure that cannot be measured by the measurement unit occurs. 3. The uninterruptible power supply system according to claim 1 , wherein when determining that the storage battery has reached the end of life, the life determination unit notifies the user of the battery life and prompts the user to replace the battery.

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