JP2002354708A - Uninterruptible power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply which can indicate an accurate time for possible back up. SOLUTION: An ambient temperature of a lead storage batter is measured, a life drop index K is calculated from the ambient temperature, a reduced time-of-use L of the lead storage battery is calculated by multiplying the life drop index K and the time-of-use of the lead storage battery, a capacity coefficient M for possible discharging is calculated by the reduced time-of-use L, an expected life time and an expected capacity ratio in the expected life time and indicate the time in which the back-up of the load is possible from the capacity coefficient M for possible discharging, a charged quantity (%) of the lead storage battery and the power consumption of the load. The life drop index K uses of an equation K=2[(T<-> T<0)/10> ] in the predetermined temperature range where T0=25 deg.C. The capacity coefficient M for possible discharging uses M=1-(expected capacity ration in the expected life time ÷expected life time)×reduced-time-of-use L. An arrangement, operation and memory of these data are carried out in a microcomputer control part 20.

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.

[0002]

2. Description of the Related Art As a countermeasure for the occurrence of a power failure in a commercial power supply, use of an uninterruptible power supply having a built-in storage battery such as a lead storage battery has become widespread.

FIG. 5 is a block diagram of a conventional uninterruptible power supply. Reference numeral 21 denotes an uninterruptible power supply main unit, which includes a lead storage battery 3, a charger 2, a power failure detection circuit 22 for detecting a power failure of the commercial power supply 1, and converts an output from the lead storage battery 3 into an alternating current during a power failure to supply power to the load 6. It comprises an inverter 4 to be supplied, an AC current detection circuit 24, and a UPS switch 5 for switching the output from the commercial power supply 1 or the inverter 4.

That is, in the uninterruptible power supply, AC power is always supplied from the commercial power supply 1 to the load 6 through the UPS switch 5, and the AC power of the commercial power supply 1 is converted into DC power by the charger 2. The lead storage battery 3 is charged. When the commercial power source 1 loses power, the power failure detection circuit 22
To the inverter 4 side to cut off the power supply from the commercial power supply 1 to the load 6.

[0005] Thereafter, upon receiving the start signal from the power failure detection circuit 22, the inverter 4 starts immediately, converts the DC power of the lead storage battery 3 into AC power, and supplies power to the load 6 through the UPS switch 5.

[0006] Recently, there has been a demand for a structure capable of displaying a time during which backup can be performed by an uninterruptible power supply in the event of a commercial power failure. In other words, there is a request from the user to take a backup of the memory while the uninterruptible power supply is operating, or to normally terminate the equipment being used.

The time during which backup by the uninterruptible power supply is possible has been determined mainly in accordance with the power consumption of the load 6 being used, the nominal capacity of the lead storage battery 3 and the state of charge. Although the power consumption of the load 6 can be relatively easily determined by the load power detection circuit 23, it is difficult to determine the state of charge of the lead storage battery 3.

Therefore, conventionally, the state of charge of the lead storage battery 3 is measured by the method shown in FIGS. That is, when the lead-acid battery 3 is charged by the charger 2, generally, as shown in FIG. Is used.

In this method, as shown in FIG. 3, when the charge amount (%) at the initial stage of charge is low, the battery is mainly charged with a constant current.
As the charge amount (%) gradually increases, that is, as the voltage of the lead storage battery increases, the charge current value is reduced, and finally the battery is charged at a constant voltage.

Therefore, as shown in FIG. 3, the method of determining the charge amount (%) of the lead storage battery 3 is (1) a method of determining from the charge voltage value or (2) a determination of the charge current value. One of the methods was used.

The charging current from the charger 2 to the lead storage battery 3 can be measured by converting the voltage into a voltage with the shunt 8, digitizing the voltage with the A / D converter 11 a, and inputting it to the charge state detection circuit 12. .

The charging voltage of the lead storage battery 3 is determined by the A / D converter 11b.
, And can be measured by inputting to the charge state detection circuit 12 and the charger control unit 7. The charge state detection circuit 12 calculates the amount of charge (%) of the lead storage battery according to the charge current and the charge voltage, and outputs the result to the backup time calculation circuit 13.

On the other hand, the charger control unit 7 controls the charger 2 in accordance with the charging current and the charging voltage of the lead storage battery 3 so as to perform constant current-constant voltage charging as shown in FIG.

The power consumption of the load 6 is calculated by the load power detection circuit 23.
And then input to the backup time calculation circuit 13.

The backup time calculation circuit 13 calculates the time during which backup can be performed by the uninterruptible power supply from the nominal capacity of the lead storage battery 3 being used, the charge amount (%), and the power consumption of the load 6, and outputs the calculated time. It was output to the display 17 via the port 16 and displayed.

[0016]

However, according to the above-described method, although the amount of charge (%) of the lead storage battery 3 and the power consumption of the load 6 can be grasped, it is not possible to accurately estimate the backup available time. The problem of difficulty was recognized.

That is, the above-mentioned conventional method does not consider the influence of the aging deterioration of the dischargeable capacity of the lead storage battery. And it has been clarified that the aging of the lead storage battery is greatly affected by the environmental temperature during use.

For example, a lead-acid battery having an ambient temperature of 25 ° C. and an expected life of 5 years in normal use has an ambient temperature of 35 ° C.
At 25 ° C., the expected life is 2.5 years, which is half of 25 ° C., and at an ambient temperature of 45 ° C., the expected life is 1.25 of １ ／ of 25 ° C.
It is known that it will be years (Fig. 4). In general, a state in which the charge capacity is reduced to half (50%) of the initial discharge capacity in a fully charged state is called the life of the lead storage battery.

This law states that the corrosion of the grid of the electrode plate, which is a factor of the life of the lead-acid battery, increases by 2 ° every time the ambient temperature increases by 10 ° C.
It is based on the law of chemical reaction, generally known as Arrhenius' law, which proceeds at twice the speed.

When a lead storage battery is used for 5 years or more, it is known that the life of the active material is reduced due to other factors, such as falling of the active material from the current collector and increase in internal resistance, regardless of the ambient temperature. Have been.

An object of the present invention is to provide an uninterruptible power supply capable of more accurately displaying the time during which backup is possible.

[0022]

In order to solve the above-mentioned problems, an uninterruptible power supply according to the present invention comprises a life deterioration coefficient K calculated from an ambient temperature of a lead storage battery during use, and a converted use time L calculated from use time. Is calculated from the converted usage time L, the expected life, and the capacity ratio at the expected life, and the dischargeable capacity coefficient M, the charge amount (%) of the lead storage battery, and the power consumption due to the load are calculated. Therefore, the time at which backup is possible is accurately displayed.

That is, in the first invention, the ambient temperature of the lead storage battery is measured, the life reduction coefficient K is calculated from the ambient temperature, and the life reduction coefficient K is multiplied by the actual use time of the lead storage battery. Calculate the converted use time L of the storage battery, calculate the dischargeable capacity coefficient M from the converted use time L, the expected life and the expected capacity ratio at the expected life time, and calculate the dischargeable capacity coefficient M and the charge amount of the lead storage battery. Are integrated, and the time during which the load can be backed up is calculated and displayed from the value obtained by the integration and the power consumption of the load. That is, in the first invention, the situation of deterioration of the lead storage battery due to the ambient temperature is considered.

In the second invention, the life reduction coefficient K is obtained by an equation of K = 2 ^{[(T− T0) / 10] in} a predetermined temperature range (where T is the average ambient temperature and T0 is the average ambient temperature).
Is a constant value. ), When the average ambient temperature T is lower than the above-mentioned T0, a life reduction coefficient K considered as T = T0 is used. In the third invention, the T0 is 25 ° C.
In the fourth invention, the dischargeable capacity coefficient M is obtained by an equation of M = 1− (expected capacity ratio at expected life / expected life) × converted usage time L. And

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the method and apparatus according to the present invention will be described below with reference to FIGS. 1. Uninterruptible power supply main body The uninterruptible power supply main body 21 according to the present invention is a lead storage battery 3,
A power failure detection circuit 22, which detects a power failure of the charger 2, the commercial power supply 1,
In the event of a power failure, the inverter 4 that converts the output from the lead storage battery 3 into alternating current and supplies power to the load 6, the alternating current detection circuit 23, and switches the output from the commercial power supply 1 or the inverter 4 U
It is composed of a PS switch 5.

That is, in the uninterruptible power supply, AC power is always supplied from the commercial power supply 1 to the load 6 through the UPS switch 5, and at the same time, the AC power of the commercial power supply 1 is converted into DC power by the charger 2. The lead storage battery 3 is charged.

When the commercial power supply 1 fails, a power failure detection circuit 22
Switches the UPS switch 5 to the inverter 4 side and cuts off the power supply from the commercial power supply 1 to the load 6.

Upon receiving the start signal from the power failure detection circuit 22, the inverter 4 starts up immediately, converts the DC power of the lead storage battery 3 into AC power, and loads the load 6 through the UPS switch 5.
To supply power.

In the present embodiment, a 12V (2V
A series connection of 12 monoblock lead-acid batteries with a nominal capacity of 7 Ah (approximately 144 cells)
V). The expected life of the lead storage battery 5 when the ambient temperature is 25 ° C. and the normal use is about 5 years.

2. Microcomputer control unit 2.1 Calculation of power consumption by charge amount and load of lead storage battery The charging current from charger 2 to lead storage battery 3 is converted to voltage by shunt 8 and digitized by A / D converter 11a. It is input to the charge state calculation circuit 12 and the charger control unit 7. on the other hand,
The voltage at the time of charging the lead storage battery 3 is digitized by the A / D converter 11b and input to the charge state detection circuit 12 and the charger control unit 7.

The charger control unit 7 controls the charger 2 in accordance with the charging current and charging voltage of the lead storage battery 3 so as to perform constant current-constant voltage charging as shown in FIG.

The charger 2 of the lead storage battery 5 has a maximum charging current of 0.7 A (0.1 C
A). The highest charging voltage in the fully charged state is 2.275 V / cell (164 V in total).
(FIG. 3).

That is, as the lead storage battery 5 is charged, the charger 2 is controlled so that the charging current gradually decreases and the charging voltage gradually increases. Finally, the charging voltage was controlled to be constant at 164V.

The state-of-charge detection circuit 12 calculates the charge amount (%) of the lead-acid battery from the relationship between the charge current and the charge voltage of the lead-acid battery 3 (FIG. 3). Added output.

On the other hand, the power consumption of the load 6 is input to the backup time calculation circuit 13 after the load power detection circuit 24 calculates the AC power value from the AC current value and the voltage value.

2.2 Dischargeable Capacity Factor M of Lead-Acid Battery 2.2.1 Measurement of Ambient Temperature of Lead-Acid Battery The ambient temperature of the lead-acid battery 3 is measured and accumulated every minute as described later (FIG. 2). ), Which stores the average value of the temperature accumulated over one hour. For example, a temperature sensor 18 such as a thermistor is directly fixed to the outer wall of the battery case of the lead storage battery.

That is, the temperature of the lead storage battery 3 measured by the temperature sensor 18 is digitized by the A / D converter 11c, and is input to the storage unit corresponding to each temperature of the temperature counter 14 every hour. And add. That is,
The temperature counter 14 is a memory that accumulates and stores the time used at 25 ° C. or less, the time used at 26 ° C.,..., The time used at 50 ° C. or more.

2.2.2 Calculation of Life Deterioration Coefficient K and Reduced Use Time L of Lead-Acid Battery In the dischargeable capacity coefficient calculation circuit 15, the values input to the respective memories in the temperature counter 14 at first are also used. Then, the life deterioration coefficient K is calculated, and the use time when converted to use at 25 ° C. (hereinafter referred to as converted use time L) is calculated by the following means.

The life reduction coefficient K of a lead storage battery can be calculated using the so-called Arrhenius law. That is, K = 2 ^{[(T-T0) / 10]} . Here, T is the average periodic temperature, and T0 is the constant ambient temperature at the time of calculating the life end integrated value.

As shown in FIG. 4, when the average ambient temperature T is lower than a predetermined temperature range (25 ° C.), the life reduction coefficient K is calculated by assuming that T = T0. on the other hand,
If the average ambient temperature T is higher than a predetermined temperature range (50 ° C.), the average ambient temperature T is regarded as the predetermined temperature range (that is, T = 50 ° C.) and the life reduction coefficient K is set.
Was calculated.

Therefore, in the following, the calculation was performed using the following equation ^: K = 2 ^{[(T−25) / 10]} (1)

Then, the relationship between the converted use time L of the lead storage battery and the actual use time was calculated as L = actual use time × K (2).

For example, according to equation (2), use at 26 ° C. for 1 hour corresponds to 1.07 hours as the conversion use time L at 25 ° C. In addition, the use at 35 ° C. for 1 hour corresponds to the use of 2 hours as the converted use time L at 25 ° C.

2.2.3 Calculation of Dischargeable Capacity Coefficient M of Lead-Acid Battery Next, the dischargeable capacity coefficient calculation circuit 15 calculates the converted use time L
, The dischargeable capacity coefficient M is calculated.

As described above, in the lead storage battery, the expected capacity at the end of the expected life is half of the initial discharge capacity. Therefore, assuming that the initial dischargeable capacity coefficient M is 1, 2
When used at 5 ° C. for 5 years (after 43,800 hours), the expected capacity ratio at the expected life is 0.5. That is, M = 1− (expected life ratio at expected life 寿命 expected life) × converted use time L (3) That is, the dischargeable capacity coefficient M of the lead storage battery used at 25 ° C. for 5 years is the above (3) In this case, the dischargeable capacity coefficient M is 0.5.

M = 1− (0.5 ÷ 43800) × 43800 = 0.5 Further, assuming that the lead storage battery has been used at 35 ° C. for 2 years (17520 hours), K = 2 from the equation (1). 2
From the equation (2), the conversion use time L at 5 ° C. is L = 2 × 17520 hours, that is, it is equivalent to 35040 hours (4 years) at 25 ° C.

At this time, the dischargeable capacity coefficient M of the lead storage battery obtained from the equation (3) is M = 0.6.
It is estimated that it has deteriorated to 60% of the discharge capacity at the beginning of use.

M = 1− (0.5 ÷ 43800) × 35
040 = 0.6 2.3 Calculation of Backup Available Time The backup time calculation circuit 13 calculates the charge amount (%) of the lead storage battery 3 output from the charge state calculation circuit 12 and the dischargeable capacity coefficient calculation circuit 15 Based on the dischargeable capacity coefficient M output from and the power consumption of the load 6 output from the load power detection circuit 23, a time during which backup can be performed by the uninterruptible power supply is calculated, and This is a part for outputting to the display 17.

For example, an initially fully charged state (a charge amount of 10
0%), it is assumed that a lead-acid battery capable of backing up a certain load 6 for 60 minutes is used. After the battery is used at 35 ° C. for two years (17520 hours), the time when backup by the uninterruptible power supply is possible is compared between the conventional method and the method according to the present invention as follows. did.

(Display time during which backup is possible in the case of using the conventional method) In the conventional method, the discharge time when the charge amount of the lead storage battery is 90% and the battery is used at 35 ° C. for 2 years (17520 hours) is as follows. It was displayed as in equation (4).
That is, conventionally, the deterioration of the discharge capacity due to the use condition has not been considered.

60 minutes × 0.9 = 54 minutes (4) (Display time during which backup is possible when using the method according to the present invention) In the method according to the present invention, the charged amount of the lead storage battery is 90%, 35%. The discharge time when used for 2 years (17520 hours) at ° C. is expressed as in equation (5).

60 minutes × 0.9 × 0.6 (M) = 32.4 minutes (5) That is, in the method according to the present invention, in addition to the charge amount (%) of the lead storage battery and the power consumption by the load, Since the backup available time is calculated and displayed in consideration of the use temperature of the lead storage battery, a more accurate display can be performed as compared with the conventional method. As a means for displaying the backup available time, for example, a bar graph display using an LED or a numerical value of 32.4 minutes can be displayed.

2.4 Software According to the Present Invention The software for calculating the time during which the uninterruptible power supply according to the present invention can back up the load is shown in FIG.
This will be described in detail with reference to FIG.

In step ST100, the time counter of 25 ° C. to 50 ° C. in the temperature counter 14 is first cleared to zero. As described above, when the temperature is 25 ° C. or less, the data is stored in the 25 ° C. counter, and when the temperature is 50 ° C. or more, the data is stored in the 50 ° C. counter.

In step ST110, a timer for measuring the use time of the lead storage battery is started.

In step ST120, it is checked whether one minute has elapsed.

In step ST130, the ambient temperature is read from the temperature sensor 18 through the A / D converter 11c. That is, the ambient temperature is measured every minute.

In step ST140, the ambient temperature read every minute is added to the average temperature area.

In step ST150, it is checked whether one hour has elapsed.

In step ST160, if one hour has elapsed, the value of the average temperature area is divided by 60, and the quotient is set in the average temperature area. By this operation, the average temperature for one hour of the temperature measured every minute is set in the average temperature area.

In step ST170, it is checked whether the value of the average temperature area 8 is 24 ° C. or less.

In step ST180, if the average temperature area is 24 ° C. or less, 25 ° C. is set in the average temperature area. At a temperature of 25 ° C. or lower, the demand for the storage battery is assumed to be constant at 5 years.

In step ST200, the temperature counter 14 corresponding to the temperature of the average temperature area is incremented by one.

In step ST210, the A / D converter 11
The charge current value is read into the charge state detection circuit 12 from a.

In step ST 220, the state of charge (%) is calculated by the state of charge detection circuit 12, and the result is output to the backup time calculation circuit 13.

In step ST230, the dischargeable capacity coefficient calculating circuit 15 is calculated based on the temperature environment in which the lead storage battery has been used.
Calculates the dischargeable capacity coefficient M, and outputs the result to the backup time calculation circuit 13.

In step ST240, the power consumed by the load 6 is measured by the load power calculation circuit 23, and the result is output to the backup time calculation circuit 13.

In step ST250, the backup time calculation circuit 13 determines the dischargeable time during which the load 6 can be backed up based on the charge amount (%) of the lead storage battery, the dischargeable capacity coefficient M, and the power consumption of the load 6. calculate.

In step ST260, the dischargeable time is displayed on the display 17 through the output port 16.

In step ST270, 0 is input to the average temperature area.

In step ST280, after the timer is initialized, the process returns to step 120.

[0072]

As described above, the uninterruptible power supply according to the present invention takes into consideration the ambient temperature at which the lead-acid battery has been used, in addition to the charge (%) of the lead-acid battery and the power consumption by the load. I have. Therefore, the time that can be backed up by the uninterruptible power supply can be displayed more accurately than before, which is excellent.

[Brief description of the drawings]

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

FIG. 2 is software of an uninterruptible power supply according to the present invention.

FIG. 3 is a schematic diagram showing changes in charging current and charging voltage of a lead storage battery during charging.

FIG. 4 shows a relationship between the ambient temperature and the life of a lead storage battery.

FIG. 5 is a block diagram of a conventional uninterruptible power supply.

[Explanation of symbols]

1: commercial power supply, 2: charger, 3: lead storage battery, 4: inverter, 5: UPS switch 6: load, 7: charger controller,
8: shunt, 9: charging current detection circuit, 10: storage battery voltage detection circuit, 11a to c: A / D converter, 12: charge state calculation circuit, 13: backup time calculation circuit, 14:
Temperature counter, 15: dischargeable capacity coefficient calculation circuit, 1
6: output port, 17: display, 18: temperature sensor, 2
0: microcomputer control unit, 21: uninterruptible power supply main unit, 2
2: Power failure detection circuit, 23: Load power detection circuit

Continued on the front page F term (reference) 2G016 CB12 CB31 CC01 CC06 CC07 CC10 CC12 CC13 CC16 CC21 CC23 CC27 CD14 CF06 5G003 AA01 BA01 CA01 CA11 CB01 CC02 DA07 DA18 EA08 FA08 GB06 GC05 5G015 FA04 GA04 HA13 JA21 JA34 JA35 JA59 KA05 A06 A05A06 A AA17 BB05 DB02 DB07 DC02 DC05 DC08

Claims (4)

[Claims] 1. An ambient temperature of a lead storage battery is measured, a life reduction coefficient K is calculated from the ambient temperature, and the life reduction coefficient K is multiplied by the actual usage time of the lead storage battery to convert the lead storage battery's conversion usage time L Is calculated from the converted usage time L, the expected life and the expected capacity ratio at the expected life, and the dischargeable capacity coefficient M and the charge amount of the lead storage battery are integrated. An uninterruptible power supply device that calculates and displays a time during which the load can be backed up from the value obtained as a result and the power consumption of the load. 2. The service life reduction coefficient K is determined by an equation of K = 2 ^{[ (T−T0) / 10] in} a predetermined temperature range (where T is an average ambient temperature and T0 is a constant value). 2. The uninterruptible power supply according to claim 1, wherein when the average ambient temperature T is lower than T0, a life reduction coefficient K assumed to be T = T0 is used. 3. The uninterruptible power supply according to claim 2, wherein said T0 is 25 ° C. 4. The dischargeable capacity coefficient M is M = 1−1.
4. The uninterruptible power supply according to claim 1, wherein the expected capacity ratio at the expected service life / expected service life is calculated by the following formula.