JPH0723906B2 - Battery monitoring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a storage battery monitoring device capable of automatically correcting an integration error in the calculation and measurement of the amount of electricity possessed by a storage battery efficiently and without impairing the life of the storage battery. is there.

[Prior Art] Generally, a storage battery has a shortened life if it is repeatedly overcharged or overdischarged. Further, overcharge causes a power loss and a decrease in an electrolytic solution, and overdischarge causes a significant voltage drop. Therefore, in order to prevent this, it is required to detect the charge limit and discharge limit of the storage battery and operate the storage battery within this limit.

FIG. 3 is a circuit diagram showing a part of a conventional storage battery monitoring device in a block diagram. In the figure, (1) is an unstable DC power supply device such as a solar cell, (2) is a diode for preventing backflow connected to the current supply side of the DC power supply device (1), (3)
Is a power switch connected to the diode (2).

(4) is a storage battery as an electric power storage device connected between the power switch (3) and the other end of the DC power supply (1), and the DC power supply when the power switch (3) is closed. (1)
It is designed to be charged by.

(5) is a shunt connected in series with the storage battery (4),
The current flowing in the storage battery (4), that is, the charging / discharging current I _B is detected.

(6) is a plurality of load switches each having one end connected to the power switch (3), and (7) is a plurality of loads connected to the other end of each load switch (6). When the container (6) is closed, the storage battery (4) is connected to the load (7) connected to it.
Power is supplied from.

(8) is an auxiliary power source connected to both ends of a series circuit composed of a storage battery (4) and a shunt (5), and an AC power source (8a)
And a switching element (8b) such as a thyristor,
By appropriately controlling the conduction ratio of the switching element (8b), an appropriate current is supplied to the storage battery (4) to charge it.

(9) is a battery monitoring device, calculates the shunt held electric quantity AH (ampere-hours) of the battery from the charge-discharge current I _B detected in (5) (4), based on the results, the power-off The switching element (8b) of the switch (3), the load switch (6) and the auxiliary power supply (8) is controlled to be opened and closed.

The conventional storage battery monitoring device is configured as described above, and operates the storage battery (4) within the charge limit and the discharge limit by continuously calculating and measuring the stored electricity amount AH of the storage battery (4),
The difference between the required power of the DC power supply device (1) and the required power of the load (7) is compensated for by the discharged power of the storage battery (4), so that the load (7) is always supplied with stable power.

In other words, if the quantity of electricity AH held exceeds the upper limit value, the power switch (3) is opened to prevent overcharging, and then the pumping of the power switch (3) is prevented. When the amount of stored electricity AH decreases, turn on the power switch (3) again.

Also, when the capacity of the DC power supply (1) such as a solar cell becomes insufficient due to weather conditions and the amount of electricity AH held falls below the specified value, the load switch (6) is opened appropriately to reduce the load. To reduce current consumption. At this time, the backup power supply (not shown) supplies power to the load (7) that cannot be shut down. Even if the load amount is reduced, if the stored electricity amount AH further decreases and reaches the lower limit, the auxiliary power supply (8)
The switching element (8b) therein is turned on, and the storage battery (4) is charged until the stored electricity amount AH recovers to a specified value or more.

In order to perform such control, it is necessary to continuously calculate and measure the stored electricity amount AH of the storage battery (4), and the calculation method is as follows.

AH = AH ₀ + [(I _B i ₁ + I _B i ₂ + ... + I _B ij) η- (I _B m ₁ + I _B m ₂ + ... + I _B mn] t / 3600 (j + n) ……
However, AH ₀ : Initial amount of electricity I _B i _{1 to} I _B ij: Charging current (A) η: Charging efficiency I _B m _{1 to} I _B mn: Discharge current (A) t: Calculation cycle (sec) j + n: sampling number t seconds that is, constantly detects the discharge current I _B of battery (4) that repeatedly charged and discharged, an average value for every predetermined period t seconds, and totalizing the holdings electrical quantity AH of the time ing.

However, in reality, even a small calculation error will increase as an integrated error over a long period of time, and the value of the charging efficiency η will change depending on the charging / discharging current value and the amount of stored electricity. Due to the extreme decrease, a large error will occur between the actual stored electricity amount AH of the storage battery (4) and the calculation result in a long period of time. In order to prevent this, the storage battery monitoring device (9) of the related art turns on the switching element (8b) of the auxiliary power supply (8) periodically, for example, about once a week, and the stored electricity amount AH is 120. The storage battery (4) was overcharged until it reached about 100%, and then the stored electricity amount AH was reset to 100% to correct the accumulated error.

[Problems to be Solved by the Invention] As described above, the conventional storage battery monitoring device periodically overcharges the storage battery (4) in order to reset the accumulated error. All the above electricity amount causes power loss, and the life of the storage battery (4) is shortened.
There was a problem that the amount of electrolyte solution decreased remarkably due to the generation of gas due to overcharge, and the rehydration cycle was shortened.

The present invention has been made to solve the above-described problems, and does not perform periodic overcharging, and even during irregular charging / discharging in which the current value changes, the stored battery charge AH
It is an object of the present invention to obtain a storage battery monitoring device capable of automatically correcting the accumulated error of the calculation and measurement of.

[Means for Solving Problems] A storage battery monitoring device according to the present invention includes an upper limit detection unit that detects an upper limit voltage value of a terminal voltage corresponding to an upper limit value of the actual amount of electricity stored in the storage battery, and an actual storage battery The lower limit detection means for detecting the specific gravity value of the electrolytic solution corresponding to the lower limit value of the stored electricity amount, the upper limit detection means is a voltage divider connected to both ends of the storage battery, the lower limit detection means is the specific gravity provided in the storage battery. It is a sensor, and when each detecting means detects the upper limit value or the lower limit value, it corrects the stored electricity amount obtained by the arithmetic measurement to a value corresponding to the upper limit value or the lower limit value.

[Operation] In the present invention, when each detecting means detects the upper limit voltage value or the lower limit specific gravity value, the stored electricity amount obtained by the arithmetic measurement is automatically corrected to a value corresponding to the upper limit value or the lower limit value, The storage battery is always operated between the upper limit value and the lower limit value.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 is a circuit diagram showing a partial block diagram of an embodiment of the present invention. In the figure, (1) to (8) are the same as the above-mentioned conventional device, and (9A) corresponds to the storage battery monitoring device (9).

(10) is a voltage divider as an upper limit detecting means for detecting the terminal voltage V _B of the storage battery (4), which is connected to both ends of a series circuit composed of the storage battery (4) and the shunt (5) and connected in series. It consists of three resistors (10a) to (10c). The voltage across the center resistor (10b) is input to the storage battery monitoring device (9A).

(11) is installed in the battery case (4a) of the storage battery (4),
For example, a float-type specific gravity sensor as a lower limit detection unit that detects the specific gravity of the electrolytic solution of the storage battery (4), and a contact (11) that closes (makes) when the specific gravity of the electrolytic solution falls below a specified value.
have a). Then, the detection signal from the contact (11a) is input to the storage battery monitoring device (9A).

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described. Battery monitoring device (9A) by using the charge-discharge current I _B of battery (4), the held electric quantity AH of the battery (4) is measured by calculating the equation in the same manner as described above, the switches on the basis of the result (3), (6) and the switching element (8b) are controlled.

Here, a case will be described in which an accumulated error occurs in the calculation measurement value in the storage battery monitoring device (9A) for the above reason.

First, when the integration error is negative, the actual stored electricity amount AH of the storage battery (4) gradually moves toward the upper limit (charging) from the measured value calculated by the formula. However, as shown in FIG. 2, the terminal voltage V _B of the storage battery (4) tends to rise sharply near the upper limit of the stored electricity amount AH (end of charging). Therefore, the storage battery monitoring device (9A) constantly detects the terminal voltage V _B , and when the specified upper limit voltage value V _BM is reached, the stored electric quantity AH by calculation measurement is set to the upper limit voltage value V _BM of the terminal voltage. It can be corrected to the corresponding upper limit value AH _M of the stored electricity.

The charging characteristics because changes the charging current value I _B and the environmental temperature, if the upper limit voltage value V _BM variably by the charging current value I _B and the environmental temperature, it is possible to perform more accurate correction. At this time, since the upper limit voltage value V _BM is detected based on the voltage across the center resistor (10b) of the three resistors (10a) to (10c), the detection voltage value setting and variable processing are performed. Will be easier.

Next, when the integration error is positive, the actual stored electricity amount AH of the storage battery (4) is gradually lower than the calculated measurement value (discharge).
Head to. However, since the specific gravity of the electrolytic solution in the battery case (4a) of the storage battery (4) decreases almost in proportion to the amount of discharge only when discharging, the actual stored electricity of the storage battery (4) depends on the specific gravity value of the electrolytic solution. You can know the quantity AH. Specific gravity sensor (11)
Is set so that the contact (11a) is closed when the specific gravity of the electrolytic solution of the storage battery (4) reaches a specified lower limit specific gravity value. Therefore, the storage battery monitoring device (9A) can correct to the lower limit value of the stored electricity amount AH corresponding to the lower limit specific gravity value of the electrolytic solution by the contact point (11a) closing signal from the specific gravity sensor (11).

Note that the specific gravity of the electrolytic solution changes somewhat depending on the electrolytic solution temperature, that is, the environmental temperature.In the case of the float type specific gravity sensor (11), however, if a material with suitable thermal expansion is selected as the float material, the environmental temperature changes. The fluctuation of the operating point of the contact (11a) due to can be compensated. That is, if the specific gravity sensor (11) including a float material having a thermal expansion that compensates for a change in the detected value of the specific gravity due to a change in the ambient temperature is used, it is reflected in the detected value so as to cancel the temperature change. Therefore, the specific gravity sensor (11) having good specific gravity reproducibility can be realized. In particular, with respect to monitoring device of the storage battery (4) irregular charging and discharging is performed, it detects the upper limit value AH _M by divider with sudden change phenomenon of the terminal voltage V _B of the vicinity of the upper limit (10),
By detecting the lower limit value corresponding to the specific gravity of the electrolytic solution of the storage battery (4) using the specific gravity sensor (11), the detection error is controlled and the reliability can be remarkably improved.

In this way, even if an accumulated error occurs in the calculation measurement result, the stored electricity amount AH of the storage battery (4) can be managed between the specified upper limit value and lower limit value.

As the float material of the specific gravity sensor that can have a temperature compensation function, acid-resistant and oxidation-resistant plastic such as polyethylene resin is used, and its linear expansion coefficient is 4 × 10 ^-5 / ° C.
It is ~ 20 × 10 ^-5 / ℃.

On the other hand, the temperature coefficient of the specific gravity of the electrolyte to be measured for specific gravity is −
Since 7 × 10 ^-4 / ℃ about a, the thermal expansion coefficient of the reduced volume of the float member, so that it is sufficient to match the 7 × 10 ^-4 / ℃.

Therefore, if the coefficient of linear expansion of the float material is set to about (1 + 7 × 10 ⁻⁴ ) ^1/3 −1 (≈23 × 10 ⁻⁵ ), temperature change can be compensated.
That is, the coefficient of linear expansion is the temperature coefficient of the specific gravity of the electrolyte (−7 × 10 ⁻⁴
It can be seen that the error due to the temperature change of the specific gravity of the electrolytic solution is canceled by using the float material of the equivalent order (about 23 × 10 ^-5 / ° C) corresponding to / ° C).

It goes without saying that the specific gravity sensor having the same operation as described above is not limited to the float type and various types can be applied.

[Effects of the Invention] As described above, according to the present invention, the upper limit detection means for detecting the upper limit voltage value of the terminal voltage corresponding to the upper limit value of the actual amount of electricity stored in the storage battery, and the actual amount of electricity stored in the storage battery With a lower limit detection means for detecting the specific gravity value of the electrolytic solution corresponding to the lower limit value, the upper stage detection means is a voltage divider connected to both ends of the storage battery, the lower stage detection means is a specific gravity sensor provided in the storage battery, When each detecting means detects the upper limit value or the lower limit value, the stored electric quantity obtained by calculation measurement is automatically and reliably corrected to a value corresponding to the upper limit value or the lower limit value. Even in the case of irregular charging / discharging, the measurement error of the storage battery electricity can be automatically corrected, the storage battery can always be operated between the upper limit value and the lower limit value without periodic overcharging, and the storage battery power loss and Prevents life reduction
Moreover, there is an effect that a storage battery monitoring device capable of preventing the decrease of the electrolytic solution can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a partial block diagram of an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the relationship between the amount of electricity stored in a storage battery and the terminal voltage, and FIG. 3 is a conventional storage battery monitoring device. It is a circuit diagram shown by a partial block diagram. (1) ...... DC power supply device, (4) …… storage battery (4a) …… battery case, (5) …… current divider (9A) …… storage battery monitoring device, (10) …… voltage divider (10a) ~ (10c) …… resistor, (11) …… specific gravity sensor (11a) …… contact, I _B …… charge / discharge current V _B …… terminal voltage, V _BM …… upper limit voltage value AH …… retained electricity quantity, AH _M ...... upper limit in the figure, the same reference numerals denote the same or corresponding parts.

Claims (6)

[Claims] 1. A storage battery monitoring device for detecting a charge / discharge current of a storage battery to calculate and measure an amount of electricity retained in the storage battery, wherein an upper limit voltage value of a terminal voltage corresponding to an upper limit value of an actual amount of electricity retained in the storage battery is set. An upper limit detecting means for detecting and a lower limit detecting means for detecting a specific gravity value of an electrolytic solution corresponding to a lower limit value of an actual amount of electricity stored in the storage battery are provided, and the upper limit detecting means is connected to both ends of the storage battery. It is a voltage divider, the lower limit detection means is a specific gravity sensor provided in the storage battery, and when each of the detection means detects an upper limit value or a lower limit value, the stored electricity amount obtained by the arithmetic measurement is the upper limit. A storage battery monitoring device characterized by correcting the value or a value corresponding to a lower limit value. 2. The storage battery according to claim 1, wherein the voltage divider is composed of three resistors connected in series, and the voltage value is taken out from one end of one of the resistors in the center. Monitoring equipment. 3. The storage battery monitoring device according to claim 1 or 2, wherein the upper limit voltage value is variable depending on the charging / discharging current value and the environmental temperature. 4. The storage battery monitoring device according to claim 1, wherein the specific gravity sensor is a float type specific gravity sensor installed in a battery case of the storage battery. 5. The storage battery according to claim 1 or 4, wherein the specific gravity sensor includes a float material having a thermal expansion that compensates for a change in a detected value due to a change in environmental temperature. Monitoring equipment. 6. The storage battery monitoring device according to claim 1, 4, or 5, wherein the specific gravity sensor has a contact point that is closed when the specific gravity of the electrolytic solution becomes equal to or lower than the lower limit value. .