JPH02273037A - Storage battery monitoring device - Google Patents

Abstract

PURPOSE:To reduce an error between the actual retaining amount of electricity and the operated amount of the same by a method wherein the amount of retaining electricity of a storage battery is operated based on a charging efficiency, operated based on the measured voltage of the storage battery, and the measured charging current of the same. CONSTITUTION:A storage batter 6 is charged by the fluctuating output of a solar battery 1 through a reverse current precluding diode 2 and a switch 3 while the storage battery 6 supplies electric power to a plurality of loads 9 through switches 8. A storage battery monitoring device 10A measures the fluctuating output voltage VB by a voltage divider 4 at all times and obtains the charging and discharging current IB of the battery by the voltage divider 5. The storage battery monitoring device 10 opens and/or closes a power source switch 3 and the load switches 8 in accordance with the output of the solar battery. Further, the storage battery monitoring device 10 changes a charging efficiency based on a measured voltage through a CPU and a memory, accommodated therein, and operates the amount of retaining electricity based on the measured charging and discharging current and the charging efficiency to control the switches 3, 8. According to this method, an error between the actual amount of retaining electricity and the operated amount of retaining electricity may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a storage battery monitoring device for a solar power generation device or the like using a solar cell.

In particular, the present invention relates to a storage battery monitoring device that can automatically correct measurement errors in the amount of electricity held in a storage battery.

[Conventional technology] The configuration of a conventional example will be explained with reference to FIG.

FIG. 3 is a circuit diagram showing a conventional storage battery monitoring device disclosed in, for example, Japanese Unexamined Patent Publication No. 82-187266.

In Figure 3, the conventional solar power generation device consists of solar cells (
1), a backflow prevention diode (2) connected to one end of this solar cell (1), and this backflow prevention diode (2)
The power switch (3) connected to the
) and the voltage divider (4) connected in parallel to the other end of the solar cell (1).
), a shunt (5) with one end connected to one end of this voltage divider (4), a positive side connected to the other end of this shunt (5), and a negative side connected to the other end of the solar cell (1). or a connected accumulator (
6), a specific gravity sensor (7) installed in the electrolyte of this storage battery (6), a plurality of load switches (8) connected to the power switch (3), and a load switch ( 8) and a storage battery monitoring device (10).

The conventional storage battery monitoring device (10) includes a power switch (3),
A device connected to the voltage divider (4), flow divider (5), specific gravity sensor (7), and load switch (8) and consisting of, for example, a computer Next, the operation of the above-mentioned conventional example is shown in FIG. I will explain while doing so.

Figure 4 shows a storage battery (6) of a conventional storage battery monitoring device (10).
) is a flowchart diagram showing the calculation operation of the amount of electricity possessed.

The solar power generation device described above uses a solar cell (1), which is an unstable power source as a DC power source, and compensates for the difference in power required by the load (9) with the charging/discharging power of the storage battery (6). ) is a device that supplies stable power to the

A storage battery monitoring device (10) calculates the amount of electricity held in the storage battery (6), and opens a power switch (3) to prevent overcharging when the amount of electricity held is an upper limit value.

On the other hand, if the amount of electricity held is at the lower limit, all load switches (8) are opened to prevent overdischarge.

In addition, in cases other than those mentioned above, the load switch (8) is opened according to the amount of electricity held to control the increase or decrease of the load (9). In other words, if the amount of electricity held in the storage battery (6) increases, the load switch (8) is If the number of closed circuits (8) is increased and the amount of electricity held decreases, the number of closed circuits of the load switch (8) is decreased to increase or decrease the overall load, and the amount of electricity held in the storage battery (6) is decreased. Control so that it is always within the specified range.

The amount of electricity held by the storage battery (6) mentioned above is determined as follows.

In Step 40), the storage battery monitoring device (10) constantly measures the charging/discharging current Is (positive when charging, negative when discharging) of the storage battery (6) using the shunt (5).

Stella 7'' (41) calculates the amount of electricity change ΔAH (ampere hour) during the calculation cycle period t using the following equation.

ΔAH= I B If not charging (NO), proceed to step (44).

y, te, a'' (43), calculate the amount of electricity A H (n) held in case of charging from the following formula, and step (45)
Proceed to.

AH(n)-AH(n-1)+77XΔAH Furthermore, AH
(n-1) is the amount of electricity held before calculation, η (η × 1)
is the charging efficiency.

Since the storage battery (6) cannot extract all of the charged electricity as discharged electricity due to internal losses such as resistance loss and loss due to gas generation, the charging efficiency η is used to calculate the stored electricity.
Multiply by

At Step L7'' (44), the amount of electricity AH(n) held in case of discharge is calculated from the following equation, and the process proceeds to Step A (45).

AH(n) = AI-1(n-1)-ΔAH In step (45), when L seconds of the calculation period have elapsed, the process returns to step (40).

However, there are errors such as measurement errors in the above-mentioned amount of held electricity. Even if the measurement error of the charging/discharging current IB is small, this error becomes extremely large as an integrated error over a long period of time.

In addition, the charging efficiency η changes depending on the amount of electricity held, and in particular, the closer to the end of charging, the more gas is generated and it drops dramatically, and it also changes slightly depending on the size of the charging current and the temperature of the storage battery (6). Even if there is no measurement error in the charging/discharging current IB, an error will occur over a long period of time between the charging and discharging current IB and the actual amount of electricity held in the storage battery (6).

Furthermore, in the case of irregularly repeated charging and discharging use, the charging and discharging efficiency varies with each repetition and errors increase.

Therefore, the operation for correcting the error in the amount of electricity held will be explained with reference to FIG. 5.

Figure 5 shows the amount of electricity held in the storage battery (6) and the storage battery voltage VB.
FIG.

When the integration error of the storage battery monitoring device (10) is negative, the actual amount of electricity held in the storage battery (6) gradually increases (charging) more than the amount of electricity calculated and measured. As shown in the figure, since the storage battery voltage vB tends to rise sharply near the upper limit of the amount of electricity held (at the end of charging),
The storage battery monitoring device (10) can measure the storage battery voltage vB. Then, the storage battery voltage vB is the upper limit voltage E
c, the amount of electricity calculated and measured is corrected to the upper limit amount of electricity AH, which corresponds to the upper limit voltage Ec.

In addition, when the integration error is positive, the actual amount of electricity held by the storage battery (6) gradually decreases (discharges) compared to the amount of electricity held by the calculation measurement. Since the specific gravity of the electrolytic solution is approximately proportional to the amount of discharge, the actual amount of electricity held by the storage battery (6) can be determined from the specific gravity of the electrolytic solution only during discharging.

In other words, the contact of the specific gravity sensor (7) closes when the specific gravity of the electrolyte in the storage battery (6) reaches the specified lower limit specific gravity value, so the amount of electricity held by calculation measurement is adjusted to the corresponding lower limit amount of electricity AHL. to correct.

There are other methods of correcting the error in the amount of electricity in addition to those described above.

For example, once a week, irrespective of the sign or negative of the integration error, overcharging is performed until the amount of electricity stored reaches approximately 120%, and then the amount of electricity calculated and measured is reset to 100%. , there is a method to correct the integration error.

However, this method has the disadvantage that more than 100% of the stored electricity results in power loss, shortens the life of the storage battery (6), and significantly reduces the amount of electrolyte due to gas generation due to overcharging. There are drawbacks.

[Problem B to be Solved by the Invention] In the conventional N battery monitoring device as described above, even if the integration error becomes large to a certain extent, error correction is not performed until the storage battery voltage reaches the upper limit value or the lower limit value. If the amount of correction becomes large and the integration error is in either the positive or negative direction, the range of use of the stored electricity of the storage battery will be narrowed, and the usage range will tend to be biased toward the charging side or the discharging side, shortening the life of the storage battery. There was a problem.

In addition, when the load is controlled by opening and closing the load switch according to the calculated and measured amount of electricity, there is a problem that the control state changes suddenly due to a large change in the amount of electricity that is stored during error correction. there were.

Furthermore, the storage battery voltage during charging varies depending on the charging current or electrolyte temperature even if the amount of electricity held is the same (for example, large charging current → high voltage, high electrolyte temperature → For this reason, accurate correction cannot be made unless the upper limit voltage Ec is made variable according to the photoelectric current or electrolyte temperature.As a result, the same problem as mentioned above occurs, and the upper limit voltage Ee cannot be adjusted. In the case of making it variable, there is a problem that the device becomes complicated and the cost increases.

This invention was made in order to solve the above-mentioned problems, and its purpose is to obtain a storage battery monitoring device that can always reduce the error between the actual amount of electricity held in a storage battery and the amount of electricity calculated and measured. shall be.

[Means for Solving the Problems] A storage battery monitoring device according to the present invention includes the following means.

(i) Charging efficiency variable means that measures the voltage of the storage battery and changes the charging efficiency based on the voltage.

(ii) A retained electricity amount calculation means that measures the charging/discharging current of the storage battery and calculates the retained electricity amount of the storage battery based on the charging/discharging current and the charging efficiency.

[Operation] In the present invention, the voltage of the storage battery is measured by the charging efficiency variable means, and the charging efficiency is changed based on the measured voltage.

Further, the charging/discharging current of the storage battery is measured by the stored electricity amount calculation means, and the amount of electricity held by the storage battery is calculated based on the charging/discharging current and the charging efficiency.

[Example] The configuration of the embodiment will be explained with reference to FIG.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which the solar cell (1) to storage battery (6), load switch (8) and load (9) are those of the above-mentioned conventional solar power generation device. is exactly the same.

In FIG. 1, a solar power generation device using an embodiment of the present invention is composed of the same components as the conventional device described above and a storage battery monitoring device (10^).

A storage battery monitoring device (IOA), which is an embodiment of the present invention, is connected to a power switch (3), a voltage divider (4), a current divider (5), and a load switch (8), and is connected to, for example, a computer (
Including attached equipment such as CPU, memory, interface, etc.
).

By the way, the charging efficiency variable means of the present invention, in the above-described embodiment of the present invention, is composed of program steps that change the charging efficiency according to the storage battery voltage, and the retained electricity amount calculation means calculates the retained electricity amount from the charging/discharging current and the charging efficiency. It consists of program steps to determine the quantity of electricity.

Next, the operation of the above embodiment will be explained with reference to FIG.

FIG. 2 is a flowchart showing the operation of one embodiment of the present invention.

Stella 7'' (20) to (24) are the steps of the above-mentioned conventional example.

The operations are the same as those in (40) to (44). Note that η is 9
It is around 5%.

In step (25), the storage battery monitoring device (108)
is the storage battery voltage v of the storage battery (6) by the voltage divider (4)
Measure R.

If the cumulative error in the amount of electricity held is negative, the actual amount of electricity held in the storage battery (6) gradually increases (charging) compared to the calculated amount of electricity held, and the voltage vB of the storage battery (6)
As shown in Fig. 5, there is a tendency for the storage battery monitoring device W (
IOA) can measure its voltage VB.

At step 7° (26>), it is determined whether the N battery voltage vB exceeds the upper limit voltage Ec. If it does (YES), proceed to step (27); if it does not (NO), proceed to step (27). Proceed to step (28).

In Stellaf Responsibility27), charging efficiency η is its upper limit ηH
Only when it is smaller (η × ηH), then the charging efficiency η is increased by Δη every 2 hours. Note that tl is about 1.0x60 seconds, and Δη is about 1%.

1 TeJ'' (28), when the storage battery voltage Ve recovers to the upper limit voltage Ec, the charging efficiency increases every tz (h>1+) hours only when the charging efficiency η is larger than the average η (η>ηK). η is decreased by Δη. Note that t2 is 3
It is about X60X60 seconds.

Therefore, as a result of calculating and measuring the amount of electricity held as the charging efficiency η - η, if a negative integration error occurs and the storage battery voltage vB exceeds the upper limit voltage Ec, the charging efficiency η is increased from η to ηH. Therefore, from the point at which this charging efficiency η exceeds the actual value, the amount of stored electricity calculated and measured becomes greater than the amount of stored electricity that was actually charged, and as a result, the integration error gradually corrects. Error correction is performed in the direction of .

On the other hand, if the cumulative error of the amount of electricity held is positive, the storage battery (
6) The actual amount of electricity held is gradually decreasing (discharging) compared to the amount of electricity calculated and measured.

As shown in Fig. 5, the voltage vB of the storage battery (6) tends to drop sharply near the lower limit of the amount of electricity held, so N battery monitoring bag! (10^) can measure its voltage vB.

Stella y" (29), it is determined whether the storage battery voltage vB is below the lower limit voltage Ed. If it is below (YES), proceed to step (30); if it is not below (NO), proceed to step (30). Go to 7° (31).

In step (30), the charging efficiency η is set to its lower limit ηL
Only when it is larger (η>ηL), the charging efficiency η is decreased by Δη every L1 hours.

In Stella 7'' (31), when the storage battery voltage VB recovers to the lower limit voltage Ed or higher, only when the charging efficiency η is smaller than the average η (η<ηK), the charging efficiency η changes every time t2 (h>b). is increased by Δη.

Therefore, as a result of calculating and measuring the amount of electricity held with the charging efficiency η = η, a positive integration error occurs, and if the storage battery voltage vB becomes lower limit voltage Ed or less, the charging efficiency η becomes ηK
Since the charging efficiency η is reduced from the actual value to ηL, the amount of stored electricity that is calculated and measured becomes smaller than the amount of electricity that is actually charged.
As a result, the cumulative error gradually moves toward the negative direction, and error correction is performed.

In one embodiment of the present invention, as described above, the charging efficiency η used for calculating and measuring the amount of electricity held is increased by a specified amount at every specified time when the storage battery voltage exceeds a specified value; When the value becomes less than a specified value, the amount decreases by a specified amount at specified time intervals.

That is, the positive or negative error is detected by the rise or fall of the storage battery voltage, and at this time, by gradually increasing or decreasing the charging efficiency η, if the error is negative or positive, the amount of electricity held is increased or decreased. Since the error is corrected in the positive or negative direction, it is possible to solve the above-mentioned problems in the operation of the device due to large changes in the amount of electricity held when the error is corrected, and it is also possible to correct the storage battery such as charging/discharging current and electrolyte temperature. Even if the voltage characteristics change depending on the various conditions, the error is corrected on the average based on the voltage characteristics for each condition, so the above-mentioned problem with the accuracy of the correction value can be solved. .

In addition, in Fig. 2, 2 hours for t (L2>
If t+) is selected appropriately, error correction at the upper or lower limit voltage of the storage battery voltage can be maintained appropriately even after voltage recovery, and even if the measurement error is in one direction, positive or negative, the storage battery The bias of the usage area toward the charging side or the discharging side can be alleviated.

Furthermore, since error correction can be performed without periodic overcharging, problems such as power loss, shortened battery life, and decrease in electrolyte caused by overcharging can be solved.

In addition, in the above embodiment, both the positive and negative cumulative errors of the amount of electricity held are corrected by the voltage of the storage battery (6).
As long as it is during discharge, a similar operation can be expected even if a specific gravity sensor is used.

Furthermore, in the above example, the program step for calculating the amount of electricity held and the program step for changing the charging efficiency are continued in a series, but the intended purpose can also be achieved by processing each program in parallel as separate programs. Needless to say.

[Effects of the Invention 1] As explained above, the present invention includes a charging efficiency variable means that measures the voltage of a storage battery and changes the charging efficiency based on the voltage; Since the storage battery is equipped with a retained electricity amount calculation means that calculates the retained electricity amount of the storage battery based on the charging efficiency, it is possible to always reduce the error between the actual retained electricity amount of the storage battery and the calculated and measured retained electricity amount. be effective.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of an embodiment of the invention, and FIG.
The figure is a circuit diagram showing a conventional storage battery monitoring device, FIG. 4 is a flowchart showing the operation of the conventional storage battery monitoring device, and FIG.
The figure is a characteristic diagram showing the relationship between the electricity I held by the storage battery and the voltage. In the figure, (IOA>... storage battery monitoring device, (4)...
Voltage divider, (5)... shunt, (6)... storage battery. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A charging efficiency variable means that measures the voltage of the storage battery and changes the charging efficiency based on the voltage; and a charging efficiency variable means that measures the charging and discharging current of the storage battery and calculates the amount of electricity held by the storage battery based on the charging and discharging current and the charging efficiency. A storage battery monitoring device comprising a retained electricity amount calculation means and controlling a switch connected to the storage battery based on the retained electricity amount.