JPH08140280A - Battery charge control device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent recharge of nickel-hydrogen storage batteries used in automobiles. [Constitution] The charging voltage of the nickel-hydrogen storage battery is measured by a voltage measuring means, and the voltage measured 1 minute after the start of charging is compared with a preset voltage. When the measured voltage is higher than the set voltage, it is determined to be recharge and the charge is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery for a mobile body mounted on a mobile body such as an electric vehicle in the form of an assembled battery composed of an assembly of sealed nickel-hydrogen storage batteries. It relates to a controlling device.

[0002]

2. Description of the Related Art As a prior art of a device for controlling the charging of a small nickel-hydrogen storage battery, for example, Japanese Patent Application Laid-Open No. Hei.
There is one disclosed in Japanese Patent Publication No. 109833. In this prior art, the temperature change rate ΔT which is the temperature rise value per unit time of the nickel-hydrogen storage battery being charged is measured. When the temperature change rate ΔT exceeds the preset first threshold value, the charging is stopped. As a threshold value, a second threshold value (hereinafter referred to as a low threshold value) lower than the first threshold value is set within a predetermined time immediately after the start of charging. By setting a low threshold value in the initial charging stage, for example, a fully charged nickel-hydrogen storage battery (hereinafter referred to as a fully-charged storage battery) is recharged (a fully-charged nickel-hydrogen storage battery is further charged). ), The temperature starts to rise immediately after the start of recharging, so the temperature change rate reaches the low threshold value in a relatively short time, and charging is stopped.
As a result, we try to minimize overcharging.

[0003]

For example, in a large capacity nickel-hydrogen storage battery used for driving an electric vehicle or the like, if charging is started in a completely discharged state, charging is performed in the same manner as in the above-mentioned prior art. The temperature change rate increases immediately after the start. However, unlike the small-sized storage battery in the prior art, the temperature change rate has a peak in the initial stage of charging. It has been experimentally known that this peak reaches an initial peak value ten minutes after the start of charging from a completely discharged state in the case of charging a nickel-hydrogen storage battery which requires 7 to 8 hours for complete charging. There is. This initial peak value is the peak value H in the curve of the temperature change rate TV in FIG. After reaching the initial peak value H, the temperature change rate T
V decreases once and remains almost constant until just before full charge. It is presumed that the cause of the peak value H is that the internal resistance of the storage battery changes at the beginning of charging.

In a large capacity nickel-metal hydride storage battery for driving an electric vehicle, if the low threshold value of the temperature change rate is set to a value equal to or lower than the peak value H, as in the above-mentioned prior art, it is re-set. Even when not charging
Ten or more minutes after the start of charging, the rate of temperature change exceeds the low threshold value and charging is stopped. Since charging cannot be performed with this, if the low threshold value is set higher than the peak value H, the time until the temperature change rate reaches the low threshold value becomes longer and the overcharge time becomes longer at the time of recharging. As a result, there is a problem that the negative electrode material is oxidized by the oxygen gas generated from the positive electrode during overcharge, and the adverse effect on the storage battery such as the deterioration of the battery constituent material such as the separator becomes large. Was needed.

[0005]

According to another aspect of the present invention, there is provided a charge control device for a nickel-hydrogen storage battery, which is a voltage for detecting a terminal voltage during charging of an assembled battery constituted by connecting a plurality of nickel-hydrogen storage battery cells. A sensor, a comparison means for comparing a detection voltage of the voltage sensor and a preset voltage that is substantially equal to a preset terminal voltage of the assembled battery after full charging, and a charging time from the start of charging of the assembled battery. It is provided with timer means for measuring and setting a predetermined charging time, and control means for stopping charging when the detected voltage exceeds the set voltage within the predetermined charging time after the start of charging of the assembled battery. .

According to the second aspect of the invention, the predetermined charging time set in the timer means is one minute. According to the invention of claim 3, further, a temperature sensor for detecting a temperature during charging of the nickel-hydrogen storage battery cell, and a temperature change rate calculating means for obtaining a temperature change rate representing a time change of the temperature based on a detection output of the temperature sensor. A means for setting a predetermined temperature change rate and a comparing means for comparing the temperature change rate obtained by the temperature change rate calculation means with a set value of the set temperature change rate; A voltage sensor for detecting the terminal voltage of the, the detection voltage of the voltage sensor, a comparison means for comparing a predetermined charging voltage of the nickel-hydrogen storage battery when fully charged, provided in the nickel-hydrogen storage battery cell, A pressure sensor that detects an internal pressure that is the internal pressure of the nickel-hydrogen storage battery cell, a comparison unit that compares the internal pressure with a preset value, and the temperature. And a control means for stopping charging when rate is less than the set value, and the voltage and pressure are both set value or more.

According to the fourth aspect of the invention, when the temperature change rate is increasing, the charging is stopped if the internal pressure is not 0.1 kgf / cm ² or more. According to the invention of claim 5, when the temperature change rate is increasing, the charging is stopped when the internal pressure becomes 2 kgf / cm ² or more. According to the invention of claim 6, when each group obtained by dividing a large number of nickel-hydrogen storage battery cells in the assembled battery into a plurality of groups is defined as a module, a voltage sensor for measuring a charging voltage between both terminals of each module, and , The total voltage which is the total value of the charging voltage of all modules, the difference voltage between the charging voltage of the assembled battery and the total voltage is obtained, and the difference voltage is compared with a preset setting value to obtain the difference voltage. Is provided with a control means for stopping charging when is equal to or higher than a set value.

According to the invention of claim 7, the total voltage is further divided by the number of modules to obtain an average module voltage, and the difference voltage between the voltage of each module and the average module voltage is obtained.
A control means for comparing the difference voltage with a predetermined set value K and a display means for displaying the module number when the difference voltage is larger than the set value are provided. According to the invention of claim 8, the module voltages of all the modules are compared with each other, and the charging is stopped when the difference between the maximum value and the minimum value of the module voltages is 1 volt or more. The invention of claim 9 further includes a temperature sensor for detecting the temperature of the highest temperature and a temperature of the lowest temperature of the plurality of nickel-hydrogen storage battery cells constituting the assembled battery, and the detection values of both temperature sensors. Comparing means for comparing is provided, and control means for stopping charging when the difference between the detection values of both temperature sensors is equal to or greater than a predetermined value.

According to a tenth aspect of the present invention, a temperature sensor and a set for measuring the temperature of each of the nickel-hydrogen storage battery cells having the highest temperature and the temperature of each of the nickel-hydrogen storage battery cells having the lowest temperature constituting the battery pack are further provided. A temperature sensor for measuring the ambient temperature of the battery, and means for comparing the temperature of the module having the highest temperature or the temperature of the module having the lowest temperature with the temperature of the atmosphere, and the comparison result is predetermined. It is equipped with a means for stopping charging when the value is equal to or higher than the value. The invention of claim 11 has means for comparing the charging voltage after full charging with a predetermined value, and means for stopping charging when the charging voltage is higher than the predetermined value.

[0010]

According to the invention of claim 1, the charging voltage (the terminal voltage of the storage battery at the time of charging) immediately after the start of charging (after about 1 minute) when the nickel-hydrogen storage battery which is not completely charged is charged is:
It is lower than the charging voltage immediately after the start of charging when recharging a fully charged nickel-metal hydride storage battery. Therefore, it is possible to determine whether to recharge or not by detecting the charging voltage. According to the third aspect of the invention, when the nickel-hydrogen storage battery is deteriorated, both the voltage and the internal pressure increase abnormally before the full charge, and this is detected by the voltage sensor and the pressure sensor. In the invention of claim 4, when the nickel-hydrogen storage battery cell loses hermeticity, gas leakage occurs and the internal pressure does not rise. In the invention of claim 5, the upper limit of the internal pressure that can rise during charging is set lower than the general pressure resistance of the container.

In the sixth aspect of the invention, the difference between the charging voltage and the total voltage of the assembled battery represents the voltage drop of the connection line of each nickel-hydrogen storage battery cell. In the invention of claim 7, the degree of deterioration of the module is represented by the difference between the module voltage and the average module voltage. According to the invention of claim 8, when the variation of the module voltage is 1 V or more, it is determined as a failure.

In the invention of claim 9, the temperature difference between the highest temperature nickel-hydrogen storage battery cell and the lowest temperature nickel-hydrogen storage battery cell indicates the degree of deterioration of the entire battery pack. In the invention of claim 10, the difference between the ambient temperature and the temperature of the nickel-hydrogen storage battery cell is equal to or more than a predetermined value, which indicates a malfunction of the cooling device. In the eleventh aspect of the present invention, when the electrolyte is insufficient, the internal resistance of the battery rises when the battery is close to full charge, and the charging voltage abnormally rises to indicate the electrolyte shortage.

[0013]

EXAMPLES Configuration of Example A sealed nickel-metal hydride storage battery (hereinafter simply referred to as a storage battery) mounted on a moving body such as an electric vehicle has a nominal voltage of 1.
One 2V nickel-hydrogen storage battery cell (hereinafter simply referred to as storage battery cell) is connected in series to form one module. Further, 24 of these modules are connected in series (240 cells) to form one assembled battery 1. 24
The electric capacity of the whole assembled battery 1 which is a series body of 0 cells is set to about 100 Ah. The method of connecting a large number of storage battery cells in the assembled battery 1 is not limited to the one in which all of the above are connected in series, and there are cases in which series connection and parallel connection are combined. Since the nominal voltage of one storage battery cell is 1.2V, when all are connected in series, the total voltage between both terminals of the battery pack 1 is 288V. A voltage sensor 2 which is a means for detecting the voltage at both terminals of the assembled battery 1 is attached, and the measured voltage output is input to the charging control circuit 5.

The assembled battery 1 further includes a temperature sensor 3 for detecting the temperature of the electrode plate of the at least one storage battery cell.
A is provided. As the temperature sensor 3A, one having a built-in power supply and an amplifier is usually used. In this embodiment, three temperature sensors are provided, and the first temperature sensor 3A is provided.
Is attached to the storage battery cell which has the lowest heat dissipation in the assembled battery 1 and therefore has a high temperature. Second temperature sensor 3B
Is the one that has the most heat dissipation and is therefore attached to the storage battery cell that has the lowest temperature. The third temperature sensor 3C is arranged in the vicinity of the battery pack 1 to measure the temperature around the battery pack 1.
The assembled battery 1 is further provided with a pressure sensor 4 in at least one of the many storage battery cells. The pressure sensor 4 measures the pressure inside the sealed storage battery cell. As the pressure sensor 4, one having a built-in power supply and an amplifier is usually used.

The detection outputs of the voltage sensor 2 and the pressure sensor 4 are input to a charge control circuit 5, in which they are converted into digital signals by respective analog / digital converters (hereinafter abbreviated as ADC) 6 and 8. To be done. AD
The digital signals of C6 and C8 are input to the CPU 11 and processed as described later. In addition, the temperature sensors 3A, 3
One of the detection outputs of B and 3C is selected by the measurement switching circuit 9 according to the control mode described later, and is input to the ADC 7. The output of the ADC 7 is sent to the CPU via the measurement control circuit 10 and the temperature change rate calculation circuit 12.
11 is input. The "voltage" in the description of this embodiment means the voltage between both terminals of the storage battery cell or the voltage between both terminals of the assembled battery during charging.

As described above, in the assembled battery, 10 storage battery cells are connected to form one module, and 24 modules are connected to form one assembled battery. In the preferred embodiment, the assembled battery 1 configured as described above is provided with one voltage sensor 17 for each module and configured to measure the voltage of each module. Further, a voltage sensor switching circuit 18 is provided, and the measured voltage data of each module is time-divisionally sequentially passed through the ADC 19 to the CPU.
11 is input. The charging power source 20 is a DC power source having a predetermined voltage, and its DC output is applied to the assembled battery 1 via the charging switch 14 of the charging control circuit 5.

Operation of Embodiment Next , the operation of the charging control device of this embodiment will be described.
When the temperature detected by any one of the temperature sensors 3A, 3B, and 3C is T, the temperature T is 1 for each sensor under the control of the measurement control circuit 10.
The average temperature T1, T2, T3, ... For 1 minute for each sensor is obtained from the instantaneous values of 6 measurements within the time width of 1 minute. The time width for obtaining the average temperature is not particularly limited to 1 minute, and can be set to an appropriate value of about 30 seconds to 10 minutes. Each average temperature T1, T2 thus obtained
T3 ... Is input to the temperature change rate calculation circuit 12. In the temperature change rate calculation circuit 12, the average temperature T for the first one minute
1 and the average temperature T2 for the next one minute dT (T2-
T1 = dT) is calculated, and the temperature change rate TV (TV = dT / dt), which is the ratio of the temperature difference dT to the unit time dt, is calculated. The data of the temperature change rate TV is input to the CPU 11.

In the charge control device of the present invention, the temperature change rate calculation circuit 12 is used by the temperature change rate calculation circuit 12 based on the voltage and pressure detected by the voltage sensor 2 and the pressure sensor 4, respectively, and the temperature detected by the temperature sensor 3A, 3B or 3C. The calculated temperature change rate TV is used as input data of the CPU 11 to control charging in various control modes described below.

[Control Mode 1] Charging Control During Recharging The charging operation is terminated in a state where the storage battery is fully charged (hereinafter referred to as "full charge"), and the power is not used again for a certain period of time and then the charging operation is performed again. Charging is called "recharging". This recharging will overcharge the storage battery and is harmful to the storage battery and should be avoided. Control mode 1 aims to prevent this recharging. In the CPU 11, control is performed based on the detection output of the voltage sensor 2.

FIG. 2 is a graph showing the change over time of the voltage V (terminal voltage during charging) during normal charging and the temperature change rate TV of the temperature performed by the temperature sensor 3A.
The horizontal axis represents time t, and the vertical axis represents voltage V and temperature change rate TV.
Indicates. At time t1 on the horizontal axis, the assembled battery 1 is charged to about 90% of its capacity, and the voltage at this time is V1.
Is. After time t1, the voltage V and the temperature change rate VT
Rises rapidly and the slopes of both curves become steep. CPU11
Is configured to determine that charging is completed (fully charged) when the temperature change rate TV exceeds the set value TV2,
At that time t2, the charging switch 14 is opened to cut off the charging current in order to terminate the charging. The voltage at this time is V2.
After opening the charge switch 14, the terminal voltage drops to a value slightly lower than V1 in a short time. FIG. 3 shows the voltage V and the temperature change rate TV when the battery is recharged after a lapse of time (for example, 1 hour or more) in which the temperature of the storage battery returns to room temperature. As shown in FIG. 3, the temperature change rate TV starts increasing immediately and at time t.
The temperature change rate TV2 is reached at 3 (for example, ten and several minutes). On the other hand, the voltage V is slightly lower than the voltage V1 at the start of recharging, but exceeds the voltage V1 within one minute and increases toward the voltage V2. An outline of the phenomenon that occurs inside the storage battery due to this recharging will be described. Since the storage battery is already fully charged, the supplied power causes the storage battery to be overcharged. As a result, oxygen is generated from the positive electrode. The generated oxygen is reduced on the surface of the negative electrode. Reaction heat is generated by this reduction reaction and the temperature of the storage battery rises.

When the temperature change rate TV reaches TV2, the CPU
The charging switch 14 is opened by the control of 11 and charging is stopped, but overcharging is performed during the time t3 from the time from the start of recharging to the stop to the stop of charging. In the present embodiment, the voltage V one minute after the start of recharging is detected by the CPU 11, and when the voltage is equal to or higher than the voltage V1, the CPU 11 controls to open the charging switch 14 (step of the flowchart of FIG. 4). 101, 102, 103, 104). As a result, even if the battery is recharged, overcharge for more than 1 minute can be avoided, and the adverse effect on the storage battery can be minimized.

[Control Mode 2] Determining Deterioration of Storage Battery When the negative electrode active material of the storage battery deteriorates, the voltage V of the storage battery and the pressure in the storage battery cell (hereinafter referred to as internal pressure P) may increase at the end of the charging process. Are known. Generally, in nickel-metal hydride storage batteries, the chargeable capacity of the negative electrode is designed to be larger than the chargeable capacity of the positive electrode. Therefore, when a normal storage battery cell is overcharged, oxygen gas is first generated from the positive electrode. However, when the chargeable capacity of the negative electrode is smaller than that of the positive electrode due to deterioration of the negative electrode, hydrogen gas is first generated from the negative electrode. When the battery is further charged to reach the chargeable capacity of the positive electrode, oxygen gas is then generated from the positive electrode and the temperature of the storage battery starts rising. Since the hydrogen gas generated from the negative electrode fills the storage battery cell, the internal pressure P rises. If charging is further continued in this state, the safety valve of the storage battery cell opens and hydrogen gas is released to the outside.
Hydrogen gas is easily ignited and may explode, so such overcharging should be stopped immediately. Therefore, in the control mode 2, deterioration of the storage battery cell is determined by measuring the internal pressure P and detecting the increase, and if it is determined that the storage battery cell is deteriorated, charging is immediately stopped and a display for instructing replacement of the storage battery is displayed. Is configured.

Next, a control operation for dealing with the above-described deterioration determination will be described. In FIG. 1, the detection output of the pressure sensor 4 is input to the CPU 11 via the ADC 8. CP
The operation in U11 is shown in steps 110 to 116 of the flowchart of FIG. As shown in FIG. 5, when the temperature change rate TV becomes equal to or higher than the set value, it is determined that the charging is completed and the charging is stopped (steps 112 and 113). Temperature change rate T
When the voltage V and the internal pressure P become equal to or higher than the set values even though V is less than the set value, it is determined that the storage battery is deteriorated and the charging is stopped (steps 114, 115, 116). That is, when the storage battery is deteriorated, as shown in FIG.
When the temperature change rate TV is still low before it becomes fully charged,
Since the voltage V and the internal pressure P increase, the deterioration is judged from this. In this case, the display device 16 displays a warning indicating that the storage battery should be replaced (step 117). The set value of the voltage V is the voltage V2,
It is desirable to set the internal pressure P to about 2 kgf / cm ² . When charging / discharging is repeated in the assembled battery 1, each storage battery cell in the assembled battery 1 usually deteriorates uniformly at the same time. Therefore, it is usually possible to determine the deterioration of the entire battery pack 1 by determining the deterioration of one storage battery cell.

[Control Mode 3] Determination of Sealability of Storage Battery In control mode 3, the sealability of the storage battery cell provided with the pressure sensor 4 is determined. Since the pressure sensor 4 is provided only in one of the many storage battery cells of the battery pack 1, it is not possible to make a determination for other storage battery cells.
In particular, when it is necessary to more reliably determine the airtightness, more reliable storage cells can be provided with the pressure sensor 4 for more reliable determination.

If the hermeticity of the storage battery is lost, the hydrogen gas dissociated from the negative electrode of the hydrogen storage alloy is released to the outside, and there is a risk of explosion or the like. In the determination of the airtightness, the internal pressure P is set to a predetermined set value, for example, 0.1 kgf at the end of the charging process by the operation shown in steps 120 and 121 of the flowchart of FIG. 7 based on the measurement data of the pressure sensor 4.
Check to see if it is above / cm ² . In a normal storage battery cell, the internal pressure P becomes 0.5 kgf / cm ² or more at the end of charging. Therefore, when the internal pressure P is 0.1 kgf / cm ² or less, it is determined that the hermeticity of the storage battery cell is lost and gas leakage occurs. When it is determined that the hermeticity is lost, charging is stopped (step 122). Further, interlock control may be performed so that the battery cannot be charged again. If necessary, an alarm may be displayed on the display device 16 as shown in step 123.

Further, in the control mode 3, it is possible to perform safety control so that the internal pressure P of the storage battery cell does not exceed a predetermined maximum limit. The closed container of each storage battery cell is generally molded from engineering plastic such as polypropylene, and its wall thickness is set to 2.0 to 3.0 mm in consideration of heat dissipation, strength and durability. The pressure resistance of the container, which is determined by this wall thickness, is 4 to 6 kgf / cm ² in the operating temperature range of the storage battery. Therefore, the upper limit of the internal pressure P of the container that is allowed to be used is set to, for example, 2 kgf / cm ² in consideration of deterioration due to long-term use and variations in the strength of the container. When the internal pressure P exceeds that level, it is determined that an abnormality has occurred, and charging is stopped. This prevents damage to the storage battery and gas leakage. (Steps 124, 125, 12 in FIG. 7)
6).

[Control mode 4] Judgment of quality of connection line connecting each storage battery cell of the assembled battery 1 In FIG. 1, the charging voltage V between both terminals 21 and 22 of the assembled battery 1 being charged is measured by the voltage sensor 2. To do. On the other hand,
The module voltage Vm, which is the terminal voltage of each module during charging, is measured by each voltage sensor 17. The measurement output of the voltage sensor 17 is sequentially switched by the changeover switch 18 and input to the CPU 11, and the module voltages Vm of all the modules are added to each other. The voltage added to each other is called the total voltage Vadd. The total voltage Vadd obtained in this way is the sum of the voltage across the terminals of each module for all modules. Therefore, the total voltage does not include the voltage drop in a large number of connection lines that connect adjacent modules. That is, the total voltage Vadd is lower than the charging voltage V by the sum of the voltage drops in the connection lines between the modules. The charging voltage V and the total voltage Vadd are compared in the CPU 11, and the voltage difference V
d is obtained (Vd = V-Vadd). The voltage difference Vd represents the sum of the voltage drops of all the connection lines connecting the modules. Therefore, when the voltage difference Vd is equal to or larger than a predetermined value, it is determined that the connection line is abnormal due to loosening or the like, and the abnormality is displayed.
(Steps 130, 131, 1 of the flowchart of FIG.
32, 133, 133A).

Next, the total voltage Vadd is divided by the number of modules to obtain the average module voltage Vav (step 134 in FIG. 8). The module voltage Vm of all modules is compared with the average module voltage Vav, and the absolute value of the difference is | Vav−
Vm | is calculated. If the absolute value of this difference is larger than the preset value K, the module is determined to be defective (step 135 in FIG. 8). The module determined to be defective is displayed on the display unit 16 by its number or the like. Also, the module voltage Vm is compared with each other for all modules. When the variation of the module voltage Vm is equal to or more than a predetermined value, for example, 1 V, it is estimated that some of the storage battery cells in the module have a large decrease in capacity, a failure such as a short circuit of the electrode plate, and the module is abnormal. Is displayed. (Steps 137, 138 of FIG.
139).

[Control Mode 5] Judgment of Heat Dissipation and Deterioration of Storage Battery Cells Due to Variations in Temperature of Storage Battery Cells in the Battery Assembly 1 In FIG. The signals are sequentially switched and input to the ADC 7. The output of the ADC 7 is detected as a temperature value by the measurement control circuit 10 and directly input to the CPU 11. The temperature detected by each temperature sensor 3A, 3B, 3C is C
It is compared in each PU 11.

The battery pack 1 made up of nickel-hydrogen storage battery cells for an automobile is housed in a casing having a forced ventilation device. The container of each storage battery cell has a cooling fin integrally formed on its side surface. In the housing, the wind of the forced ventilation device is applied to the cooling fins to cool the storage battery cells. The temperature sensor 3A measures the temperature of the storage battery cell that should have the highest temperature in the battery pack, and the temperature sensor 3B measures the temperature of the storage battery cell that also has the lowest temperature. These temperature sensors 3A, 3
The temperature of each storage battery cell in the assembled battery to which B, 3C, etc. are attached is previously measured by comparison, and temperature sensors 3A, 3B are used.
The storage battery cell to be mounted is determined. The temperature sensor 3C is provided inside the casing and measures the temperature of the intake air of the ventilation device. The temperature of this intake air is substantially equal to the ambient temperature of the place where the assembled battery is placed.

The operation relating to the temperature measured by the temperature sensor is shown in the flowchart of FIG. Step 140,
141, 142, and 142A, when the difference between the detection values of the temperature sensors 3A and 3B is equal to or greater than a predetermined value, it indicates that the capacity of each storage battery cell has a large variation, and the entire battery pack deteriorates. It means that there is. Also in this case, the charging is stopped and the deterioration is displayed on the display unit 16. Further, as shown in steps 143, 144, and 145, the detected value of the temperature sensor 3A or 3B and the temperature sensor 3 are detected.
If the difference between the detected values of C is greater than or equal to the predetermined value, it indicates that the effect of forced ventilation is low. In this case, the ventilation system malfunctions,
This indicates that the cooling fins of the storage battery cells are clogged. Also in the above case, the charging is stopped and the abnormality is displayed on the display unit 16.

[Control Mode 6] Judgment of Insufficiency of Electrolyte Based on Increase in Charging Voltage of Storage Battery In FIG. 2, charging from time 0 to time t1 (hereinafter,
It is charged up to about 90% of full capacity by the first-stage charging). The charging method at this time is constant power charging. Constant power charging is a method of charging while keeping the power constant. Further, the battery is fully charged by the charging from the time t1 to t2 (hereinafter referred to as the second stage charging). The charging method at this time is constant current charging. Constant current charging is a current charging method for charging while maintaining a constant current. The current for the second-stage charging is usually about a fraction of that for the first-stage charging. At the time of switching from the first-stage charging to the second-stage charging, about 70% of the design charging time until full charging is the first-stage charging, and the remaining about 30%.
The time of may be the second-stage charging. Since the end of the second stage charging is close to overcharging, the voltage V remarkably rises at the end of the second stage charging when the electrolyte is insufficient. Therefore, the shortage of the electrolytic solution can be detected by detecting the increase in the voltage V. The operation of detecting the electrolyte shortage is performed in steps 146, 147, 148, 148 of the flowchart of FIG.
Shown in A. The charging voltage V at time t2 is compared with a predetermined value set by the CPU 11. When the charging voltage is higher than the predetermined value, it is determined that the electrolyte solution is insufficient, charging is stopped, and an abnormality is displayed on the display unit 16.

[0033]

According to the invention of claim 1, the voltage V after a predetermined time (for example, 1 minute) from the start of recharging is detected, and when the voltage is equal to or higher than the terminal voltage V1 at the time of full charging, recharging is performed. Then, the charging is stopped. The terminal voltage of a fully charged storage battery is the same as the predetermined time (for example, about 1 minute) during recharging.
Since the charging voltage V2 at the time of full charging is reached in a short time, it takes 1 time to exceed the terminal voltage V1 at the time of full charging.
It is a short time within minutes. Therefore, the overcharge time can be a short time within the predetermined time, and the adverse effect on the storage battery can be sufficiently reduced. According to the invention of claim 3, even if the temperature change rate is less than the set value, when the voltage and the internal pressure exceed the set values, it is determined that the storage battery is deteriorated, the charging is stopped, and the fact is displayed. Therefore, it is possible to prevent serious damage due to deterioration of the storage battery and to know it reliably.

According to the fourth aspect of the present invention, it is possible to know that the hermeticity of the storage battery cell has been lost by detecting that the internal pressure has dropped below the set value. According to the invention of claim 5, damage to the storage battery and gas leakage can be prevented by setting the upper limit of the internal pressure. According to the invention of claim 6, it is possible to know the abnormality of the connection line between the modules. According to the inventions of claims 7 and 8, it is possible to identify a defective module among a plurality of modules of the assembled battery.

According to the invention of claim 9, there is a large difference in temperature between both storage battery cells provided with both temperature sensors for the highest temperature cell and the lowest temperature cell. Can be estimated. According to the invention of claim 10, since the difference between the temperature of the storage battery and the ambient temperature is large, it is possible to know the abnormality of the ventilation device for cooling. According to the invention of claim 11, since the charging voltage abnormally rises at the end of the second stage charging, it is possible to know the shortage of the electrolytic solution.

[Brief description of drawings]

FIG. 1 is a block diagram of a charge control device for a nickel-hydrogen storage battery according to an embodiment of the present invention.

FIG. 2 is a graph showing changes over time in voltage and temperature change rates during charging of a large nickel-hydrogen storage battery.

FIG. 3 is a graph showing changes over time in voltage and temperature changes during recharging of a large nickel-hydrogen storage battery.

FIG. 4 is a flowchart showing the operation of control mode 1 in the charging control device of the present invention.

FIG. 5 is a flowchart showing the operation of control mode 2 in the charging control device of the present invention.

FIG. 6 is a graph showing changes over time in voltage and temperature change rates during charging of a deteriorated nickel-hydrogen storage battery.

FIG. 7 is a flowchart showing the operation of control mode 3 in the charging control device of the present invention.

FIG. 8 is a flowchart showing the operation of control mode 4 in the charging control device of the present invention.

FIG. 9 is a flowchart showing the operations of control modes 5 and 6 in the charging control device of the present invention.

[Explanation of symbols]

 2, 17 Voltage sensor 3A, 3B, 3C Temperature sensor 4 Pressure sensor

Front page continued (72) Inventor Noboru Ito 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Kanji Takada 1006, Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. A voltage detecting means for detecting a terminal voltage during charging of an assembled battery constituted by connecting a plurality of nickel-hydrogen storage battery cells, a detection voltage of the voltage detecting means, and a preset voltage of the assembled battery. Comparing means for comparing a set voltage substantially equal to the terminal voltage after full charge, timer means for measuring a charging time from the start of charging the assembled battery and counting a predetermined charging time, and the assembled battery A charging control device for a nickel-hydrogen storage battery, comprising: a control unit that stops charging when the detected voltage exceeds the set voltage within the predetermined charging time after the start of charging. 2. The charge control device for a nickel-hydrogen storage battery according to claim 1, wherein the predetermined charging time after the start of charging is 1 minute. 3. The nickel-hydrogen storage battery according to claim 1, further comprising: a temperature sensor that detects a temperature during charging of the nickel-hydrogen storage battery cell, and a temperature that represents a temporal change in temperature based on a detection output of the temperature sensor. Temperature change rate calculating means for obtaining a change rate, means for setting a predetermined temperature change rate, and comparing means for comparing the temperature change rate obtained by the temperature change rate calculating means with the set value of the set temperature change rate. A voltage detecting means for detecting a terminal voltage during charging of the nickel-hydrogen storage battery cell; a comparing means for comparing a detection voltage of the voltage detecting means with a predetermined charging voltage of the nickel-hydrogen storage battery at the time of full charge; , Provided in the nickel-hydrogen storage battery cell,
A pressure sensor that detects an internal pressure that is the internal pressure of the hydrogen storage battery cell, a comparison unit that compares the internal pressure with a preset value, and the temperature change rate is less than a set value, and the voltage and the internal pressure are both set values. A charging control device for a nickel-hydrogen storage battery, which has a control means for stopping charging when the above is the case. 4. The charge control device for a nickel-hydrogen storage battery according to claim 3, wherein the charging is stopped when the internal pressure is not 0.1 kgf / cm ² or more while the rate of temperature change is increasing. 5. The charge control device for a nickel-hydrogen storage battery according to claim 3, wherein the charging is stopped when the internal pressure becomes 2 kgf / cm ² or more while the temperature change rate is increasing. 6. The nickel-hydrogen storage battery according to claim 1, further comprising: when defining each group obtained by dividing a large number of nickel-hydrogen storage cells in the assembled battery into a plurality of groups as a module, between both terminals of each module. Voltage detection means for measuring the charging voltage of, and the total voltage which is the total value of the charging voltage of all modules,
Nickel having a control means for determining the difference voltage between the charging voltage and the total voltage of the assembled battery, and comparing the difference voltage with a predetermined set value, and stopping the charging when the difference voltage is equal to or higher than the set value. Charge control device for hydrogen storage batteries. 7. The nickel-hydrogen storage battery according to claim 6, further comprising: dividing the total voltage by the number of modules to obtain an average module voltage, obtaining a difference voltage between the voltage of each module and the average module voltage, and calculating the difference between them. A charging control device for a nickel-hydrogen storage battery, comprising control means for comparing a voltage with a predetermined set value K and display means for displaying the module number when the difference voltage is larger than the set value. 8. The module voltages of all modules are compared with each other, and the difference between the maximum value and the minimum value of the module voltage is 1.
The charge control device for a nickel-metal hydride storage battery according to claim 6, wherein charging is stopped when the voltage is equal to or higher than the voltage. 9. The nickel-hydrogen storage battery according to claim 3, further comprising temperature sensors for respectively detecting the temperature of the highest temperature and the temperature of the lowest temperature of the plurality of nickel-hydrogen storage battery cells forming the assembled battery, Also, a charge control device for a nickel-hydrogen storage battery, comprising a comparison means for comparing the detection values of both temperature sensors, and having a control means for stopping charging when the difference between the detection values of both temperature sensors is equal to or greater than a predetermined value. 10. A temperature sensor for detecting the temperature of each of the nickel-hydrogen storage battery cells having the highest temperature and the lowest temperature of the nickel-hydrogen storage battery cells constituting the battery pack, and an atmosphere in which the battery pack is placed. A temperature sensor for detecting a temperature, and means for comparing the temperature of the highest temperature module or the lowest temperature module with the temperature of the atmosphere, and when the temperature difference of the comparison result is a predetermined value or more. The charging control device for a nickel-hydrogen storage battery according to claim 3, wherein charging is stopped. 11. The nickel-hydrogen storage battery according to claim 1, further comprising means for comparing the charging voltage after full charging with a predetermined value, and stopping the charging when the charging voltage is higher than the predetermined value. A charge control device for nickel-hydrogen storage batteries.