JPH08163786A - Method and apparatus for controlling charging of battery bank - Google Patents

Abstract

PURPOSE: To control charging properly according to the state of battery bank such as the battery temperature, the progress of charging, etc., by conducting charging by constant power charging for a first charging period and constant current charging for a second charging period. CONSTITUTION: When charging is started, a battery bank 1 is supplied with a charging current by constant power as main charging from a charging apparatus 12. A temperature sensor 2 detects the temperature of a battery 1 at all times, and outputs the instantaneous value of the temperature as voltage, and the output is input to a CPU 8 as an instantaneous temperature data through an A/D converter 7. The CPU 8 reads the instantaneous temperature data at a plurality of times for a fixed period, and uses the mean value of the data as the temperature of the battery bank 1. A capacity reference value (the limit of charging capacity to the temperature of the battery bank 1) corresponding to the temperature of the battery bank 1 is read from a ROM. The CPU 8 reads the residual capacity of the battery bank 1 determined at all times. transmits a signal to the charging apparatus 12 and completes constant power charging when the residual capacity reaches the capacity reference value, and conducts constant current charging as supplement charging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling the charge of a storage battery in the form of an assembled battery composed of an assembly of sealed nickel-hydrogen storage batteries, etc., especially mounted on a mobile body such as an electric vehicle. Regarding

[0002]

2. Description of the Related Art Sealed nickel-hydrogen storage batteries have excellent basic characteristics such as energy density, output density, cycle life, etc., and have been developed for practical use as a power source for driving motors of moving bodies such as electric vehicles. I am advancing. When the battery is used as a power source for an electric vehicle, the battery capacity is about 50 to 120 Ah and 10 to obtain a predetermined driving output.
A total voltage of about 0 to 350 V is required. The output voltage of a nickel-hydrogen battery is 1.2, which is the minimum unit.
Since it is about V, many cells are connected in series to obtain a required total voltage. For example, connecting 10 cells in series to form one module battery,
If four batteries are connected in series, a total of 240 cells will be obtained and a total voltage of 288V will be obtained. When charging such an assembled battery, pay attention to the point that the voltage and temperature of the assembled battery rises as charging progresses, as in the case of a single battery, by applying a predetermined charging voltage between both ends of the assembled battery. To determine if charging is complete.

However, the above-mentioned assembled battery is an assembly of a large number of cells, and it is substantially impossible to manufacture such a large number of cells into physically identical ones. Therefore, even if they are connected in series as an assembled battery, there are individual differences in the discharge state of each cell. There are also subtle differences in usage conditions, such as different temperature conditions depending on the spatial arrangement of the assembled battery. As a result,
In reality, the depth of discharge is not the same depending on the cell and the module battery. Therefore, even if the entire assembled battery is charged, the progress of charging is not the same when looking at each cell. That is, even if the battery capacity of one cell has recovered to 100%, that of another cell is still 90%.
The situation like% occurs. Therefore, in order to have a battery capacity of 100% or more for all cells, it is necessary to uniformly perform supplementary charging to raise the battery capacity as a whole. FIG. 12 shows the battery temperature T, the battery voltage V, the charging current I, and the battery temperature in the case of adopting the two-stage charging method in which the charging condition is changed after the first charging period T1 and the second charging period T2 is a supplementary charging. It is a graph which shows the characteristic of rate of change dT / dt. The timing of switching the charging current from the first charging period to the second charging period is determined by capturing the change in the battery temperature T, the battery voltage V, or the change rate dT / dt of the battery temperature.

[0004]

However, the limit of the battery capacity that can be charged by the battery temperature is not constant. Therefore, if the above-mentioned conventional charging method is used to uniformly perform the supplementary charging for the second charging period in a state where this limit is lowered, there is a case where it is considerably overcharged. Further, regarding a battery having a peculiarity of an assembled battery, the discharge state of each cell is not constant as described above, but the individual difference in the discharge state may be very small. That is, in some cases, the discharge depth before charging of each cell is almost the same, and the charging is progressing uniformly. In this case, if the supplementary charge for the second charge period is uniformly performed, energy is wasted and all cells are overcharged. As described above, the conventional charging method easily causes overcharge, and the amount of overcharge of the entire assembled battery is large. Such overcharging accelerates the deterioration of the battery and thus shortens the life of the battery.

The present invention has been made to solve the above-mentioned problems, and a method and a method capable of appropriately controlling charging according to the state of the assembled battery, for example, the battery temperature and the progress of charging. The purpose is to provide a device.

[0006]

A charge control method for an assembled battery according to the present invention is a charge control method for an assembled battery composed of an assembly of a plurality of storage batteries, wherein the assembled battery is controlled under a first condition. A step of performing main charging, detecting the battery temperature of the assembled battery, obtaining a remaining capacity of the assembled battery and a capacity reference value corresponding to the battery temperature;
When the remaining capacity reaches the capacity reference value, the charging current is reduced to perform supplementary charging under the second condition.

[0007] Further, the main charging of the assembled battery under the first condition, the battery temperature of the assembled battery is detected, the remaining capacity of the assembled battery, and the capacity corresponding to the battery temperature. Obtaining a reference value, and determining the voltage across each of the module batteries and the rate of change of the voltage, the inter-module difference of the voltage when the remaining capacity reaches the capacity reference value, and When at least one of the inter-module differences in the rate of change of the voltage exceeds a predetermined value, the charging current is reduced to perform supplementary charging under the second condition, and when the predetermined value is not exceeded, the charging is terminated. It is equipped with.

After the step of performing supplementary charging, the voltage across the assembled battery and the voltage reference value for supplementary charging corresponding to the battery temperature are read, and if the difference is less than a predetermined value, supplementary charging is performed. The method further includes a step of continuing and stopping supplementary charging and issuing an alarm output if the predetermined value is exceeded.

The battery pack charge control device according to the present invention is a charge control device for a battery pack consisting of a series assembly of a plurality of module batteries, and a current detection device for detecting a charge / discharge current of the battery pack. Means, a battery capacity measuring means for integrating the current detected by the current detecting means by time, and adding / subtracting to / from the initial value of the battery capacity of the assembled battery to obtain the remaining capacity of the battery capacity; Battery temperature detection means for detecting the battery temperature, the remaining capacity, the determination means for producing a predetermined output when the capacity reference value corresponding to the battery temperature, and connected to both ends of the assembled battery to perform charging, And a charging device that receives the output to reduce the charging current and perform supplementary charging.

Further, the current detecting means for detecting the charging / discharging current of the assembled battery, and the current detected by the current detecting means are integrated by time to add / subtract to the initial value of the battery capacity of the assembled battery. Battery capacity measuring means for determining the remaining capacity of the capacity, battery temperature detecting means for detecting the battery temperature of the assembled battery, voltage detecting means for detecting the voltage across each of the plurality of module batteries, and the remaining capacity. When the capacity reference value corresponding to the battery temperature is reached, the first signal is output if at least one of the inter-module difference in the voltage and the rate of change of the voltage exceeds a predetermined value, and the second signal is output if not. And the determination means that generate the respective signals of
A charging device connected to both ends of the assembled battery for charging, performing supplementary charging while reducing the charging current when receiving the first signal, and ending charging when receiving the second signal. It is equipped with and.

Further, the current detecting means for detecting the charging / discharging current of the assembled battery, and the current detected by the current detecting means are integrated by time to add / subtract to the initial value of the battery capacity of the assembled battery. Battery capacity measuring means for obtaining the remaining capacity of the capacity, voltage detecting means for detecting the voltage across the assembled battery, battery temperature detecting means for detecting the battery temperature of the assembled battery, the remaining capacity, and battery temperature And a capacity reference means for outputting a first signal when the remaining capacity reaches the capacity reference value, the voltage, and a voltage reference value at the time of supplementary charging with respect to the battery temperature. If the difference exceeds a predetermined value, then the second
Is connected to both ends of the assembled battery for charging, and when the first signal is received, supplementary charging with reduced charging current is started, and the second signal is output. And a charging device for stopping charging when received.

[0012]

In the charge control method for the assembled battery according to the present invention, initially, the assembled battery is mainly charged under the first condition,
Next, the battery temperature of the assembled battery is detected, the remaining capacity of the assembled battery and the capacity reference value corresponding to the battery temperature are obtained, and the charging current is reduced when the remaining capacity reaches the capacity reference value. Supplementary charging is performed under the condition of 2.

Main charging of the assembled battery under the first condition is performed, then the battery temperature of the assembled battery is detected, and the remaining capacity of the assembled battery and the capacity reference value corresponding to the battery temperature are detected. And the voltage across each of the module batteries and the rate of change of the voltage. When at least one of the inter-module difference in voltage and the inter-module difference in voltage change rate when the remaining capacity reaches the capacity reference value exceeds a predetermined value, the charging current is reduced to compensate for the second condition. Charging is performed, and if the predetermined value is not exceeded, charging is terminated.

After starting the supplementary charge, the voltage across the assembled battery and the voltage reference value during supplementary charging corresponding to the battery temperature are read. If the difference is less than a predetermined value, supplemental charging is continued. If it exceeds the predetermined value, supplementary charging is stopped and an alarm output is issued.

Further, the battery pack charge control device of the present invention is
The charging / discharging current of the battery is detected by the current detecting means, and the detected current is integrated by time by the battery capacity measuring means to obtain the remaining capacity of the battery capacity by adding / subtracting to / from the initial value of the battery capacity of the assembled battery, The battery temperature of the assembled battery is detected by the battery temperature detecting means. Then, the determination means produces a predetermined output when the remaining capacity reaches the capacity reference value corresponding to the battery temperature, and the charging device thereby performs supplementary charging with reduced charging current.

Further, the battery pack charge control device of the present invention is
The charging / discharging current of the battery is detected by the current detecting means, and the detected current is integrated by time by the battery capacity measuring means to obtain the remaining capacity of the battery capacity by adding / subtracting to / from the initial value of the battery capacity of the assembled battery, The battery temperature of the assembled battery is detected by the battery temperature detecting means. Furthermore, the voltage detection means detects the voltage across each of the plurality of module batteries. When the remaining capacity reaches the capacity reference value corresponding to the battery temperature, the determination means exceeds the first signal if at least one of the difference between the modules of the voltage and the rate of change of the voltage exceeds a predetermined value. If not, each produces a second signal,
The charging device receives the first signal to perform supplementary charging with reduced charging current, and ends the charging when receiving the second signal.

Further, the charging / discharging current of the battery is detected by the current detecting means, and the detected current is integrated by the battery capacity measuring means by time to add / subtract it to / from the initial value of the battery capacity of the assembled battery. The remaining capacity is obtained, and the battery temperature of the assembled battery is detected by the battery temperature detecting means. Then, the capacity comparison means compares the remaining capacity with a capacity reference value corresponding to the battery temperature, outputs a first signal when the capacity reaches the capacity reference value, and the voltage comparison means compares the voltage with the voltage. The difference between the battery temperature and the voltage reference value during supplementary charging is compared with a predetermined value, and if the difference exceeds the predetermined value, a second signal is output. When the charging device receives the first signal, the charging current is reduced to perform supplementary charging, but when the second signal is received, the charging is stopped.

[0018]

【Example】

(Embodiment 1) FIG. 1 is an internal circuit diagram of a storage battery which is mounted on a moving body such as an electric vehicle and is composed of an assembly of sealed nickel-hydrogen storage batteries. The battery 1 includes a plurality of (for example, 24 in this embodiment) modules 101, 102,
103 ,. ． ． , And 124 are connected in series (hereinafter referred to as assembled battery 1), and each module is further composed of a series connection body of a plurality of (usually 10) cells. FIG. 2 is a block circuit diagram showing a battery pack charge control device and the like of the present invention. In FIG. 2, a pair of input terminals of the voltage detection circuits 201 to 224 are respectively connected to both ends of the modules 101 to 124, and an analog voltage output signal proportional to a voltage between both ends of the modules 101 to 124 Input to the / D converter 7. Module 1
A battery temperature sensor 2 is provided inside 02, and its output is sent to the A / D converter 7. Here, the battery temperature sensor 2 is, for example, a thermistor temperature sensor. In addition,
Although the example in which the battery temperature sensor 2 is provided in the module 102 has been described, this is shown as an example and may be provided in another module. Further, the battery temperature sensor 2 may be provided in two or more modules so that the CPU 8 takes an average or maximum output value.

Between the both ends of the assembled battery 1, a charging device 12,
Also, a series body of the switch 5 and the load 6 is connected.
The load 6 is a motor or the like in an electric vehicle. In a normal traveling state, the switch 5 is closed to supply the current to the load 6. At the time of charging, the switch 5 is opened to disconnect the load 6, and the charging device 12 applies a DC charging voltage. The plug 13 of the charging device is connected to, for example, an AC 200V power source while the electric vehicle is stopped. When the charging device 12 is activated, a signal indicating that is sent to the A / D converter 7. The current flowing through the load 6 is detected by the current sensor 3 such as a Hall element and sent to the A / D converter 7. A voltage sensor 4 using, for example, resistance voltage division is connected between both ends of the assembled battery 1, and the voltage proportional to the voltage (total voltage) between both ends of the assembled battery 1 is A /
Input to the D converter 7. The digital output signal of the A / D converter 7 is sent to the CPU 8. A ROM 9 as a storage device is connected to the CPU 8. A / D converter 7, C
The PU 8 and the ROM 9 form a charge control circuit 10. Then, the output of the CPU 8 is sent to the display device 11. The display device 11 is arranged, for example, in front of a driver's seat of an electric vehicle,
It is visible to the driver.

Next, the operation of the charging control device configured as described above will be described. First, in FIG.
While the electric vehicle is running, the switch 5 is closed and a current flows through the load 6. The current sensor 3 detects the load current, and A /
A signal corresponding to the current value is sent to the CPU 8 via the D converter 7. The CPU 8 integrates this for each unit time to obtain the consumption amount of the capacity [current / time] of the battery pack 1 and subtracts this from the initial capacity (predetermined value) to always grasp the remaining capacity at the present time. . Further, during charging, which will be described later, the charging current supplied from the charging device 12 is detected by the current sensor 3, and similarly, the CPU 8 performs integration processing, and the remaining capacity during charging is sequentially added to the immediately preceding capacity. Figure out

Next, the charging control method will be described with reference to the flowchart of FIG. For charging, the switch 5 shown in FIG. 2 is opened to disconnect the load 6, and the charging device 12 is activated to start charging. Charging is performed by constant power charging (main charging) in the first charging period and constant current charging (complementary charging) in the second charging period. To switch from constant power charging to constant current charging and to stop charging, use CP
This is done by sending a signal from U8 to the charging control device 12. First, when charging is started, the charging device 12 to 5
A charging current with a constant power of ˜6 kW is supplied to the assembled battery 1 (step S11). On the other hand, in FIG. 2, the temperature sensor 2 constantly detects the battery temperature and outputs the instantaneous value as a voltage. The output is CP through the A / D converter 7.
Input to U8 as instantaneous temperature data. CPU here
8 reads the instantaneous temperature data a plurality of times at a constant cycle, and reads the average value as data corresponding to the battery temperature T (hereinafter simply referred to as battery temperature T) (step S12).

Next, in step S13, the capacity reference value AH _ref corresponding to the battery temperature T is read from the ROM 9 (FIG. 2). Here, the capacitance reference value will be described. FIG. 4 is a graph showing the upper limit value of the battery capacity with respect to the battery temperature in a range where overcharging does not occur. This example has a battery capacity of 10
The characteristics of a battery of 0 [A · hour] are shown, but as shown in the figure, even a battery having a capacity of 100 [A · hour] can always be charged to 100 [A · hour]. Not necessarily, but the capacity limit decreases with temperature. For example, when the battery temperature is 40 ° C., charging can be performed only up to about 95 [A · hour], and when the battery temperature is −20 ° C., charging can be performed only up to about 76 [A · hour]. The practical range in which charging is possible is -20 ° C to 60 ° C. in this way,
The battery capacity at that time determines the maximum chargeable capacity. The capacity limit for the battery temperature is the capacity reference value AH _ref . As the capacity reference value AH _ref for various battery temperatures, specific numerical values shown in the graph of FIG. 4 are stored in the ROM 9 in advance.

Returning to FIG. 3, in step S13, in addition to the capacity reference value AH _ref [A · time], the remaining capacity AH [A [A
・ Read [Time]. Next, in step S14, the remaining capacity A
It is determined whether H has reached the capacity reference value AH _ref .
If it has reached, the process proceeds to step S15, and if it has not reached, the process returns to step S11. In step S15, the charging device 1
2 (FIG. 2) is sent to terminate the constant power charging, and then the constant current charging as the auxiliary charging is performed. In constant current charging, charging is performed with a minute charging current such that the remaining capacity of each module is 100% to 110%. Charging is completed when constant current charging is performed for a predetermined time.

As described above, by determining the upper limit of the originally chargeable capacity in consideration of the battery temperature, the high temperature range (for example, 40 ° C. or higher) and the low temperature range (for example, -10 ° C. or lower) where the capacity limit is lowered. In the above, since the charge limit capacity is set to be relatively low, it is possible to prevent the situation of remarkably overcharging. Therefore, overcharging causes less damage to the battery and less energy loss, so that charging efficiency is improved. As described above, when the upper limit value of the originally chargeable capacity is charged in consideration of the battery temperature (A), the upper limit value of the originally chargeable capacity is always a constant value (for example, 100 [ [A · time]), the charge / discharge test was performed for each of the case (B) in which the auxiliary charge was started when the constant value was reached. Then, it was investigated how the distance that can be traveled by one charge changes with the increase in the number of cycles (the number of times of charging and discharging). The charging current value in the first charging period was 10 A, the charging current in the second charging period was 2 A, and the charging time was 3 hours. In addition, the battery temperature during charging is -20 ° C to 4 ° C mainly considering the weather conditions throughout the year in Japan.
The temperature was set in the range of 0 ° C, and the steps were repeated in the order of -20 ° C, 0 ° C, 20 ° C, and 40 ° C. The electric discharge was performed by using the electric vehicle motor as a pseudo load. The test results are shown in FIG. In FIG. 5, the horizontal axis indicates the number of cycles, and the vertical axis indicates running (possible).
The distance [km] is shown. As is clear from the figure, in the case of A, the initial mileage is maintained even when the number of cycles reaches 200, but in the case of B, the mileage rapidly decreases with an increase in the number of cycles, and In the number of hundreds, it is less than half of the initial mileage. As described above, it is understood that the deterioration of the battery is accelerated when the charge capacity limit due to temperature is not taken into consideration (case B). This is because deterioration of the battery is accelerated due to significant overcharge particularly in the high temperature range and the low sound range.

(Second Embodiment) Next, a second embodiment will be described. FIG. 6 is a flowchart showing the charging control method in the second embodiment. The circuit configuration is shown in FIG.
Since the configuration is the same as that of 1, the description thereof will be omitted. Also,
Since steps S21 to S23 of FIG. 6 are the same as steps S11 to S13 of FIG. 3, respectively, description thereof will be omitted.
Now, in step S24 of FIG. 6, it is determined whether or not the remaining capacity AH of the battery pack 1 (FIG. 2) has reached a predetermined value for the capacity reference value AH _ref . For example, it is determined whether the remaining capacity AH has reached 90% of the capacity reference value AH _ref .
If not reached, the process returns to step S21. If it has reached, it proceeds to step S25. In step S25, as shown in FIG.
Detected by the voltage detection circuits 201 to 224 of the CPU 8
For each of the voltages Vm1 to Vm24 of the 24 modules 101 to 124 sent to, the rate of increase per unit time, that is, dVmi / dt (i = 1 to 24) is obtained. The unit time is, for example, 1 minute. Then, step S26
At, it is determined whether the remaining capacity AH has reached the capacity reference value AH _ref . If not reached, the process returns to step S21 and the above-described operation is repeated. When the remaining capacity AH reaches the capacity reference value AH _ref , the process proceeds to step S27, and the two conditions are determined. One of the conditions is module 1
It is whether or not the inter-module difference of each voltage Vmi (Vm1 to Vm24) of 01 to 124 exceeds a predetermined value. The other one is whether or not the inter-module disparity in the value of dVmi / dt exceeds a predetermined value. As an example of these predetermined values, the former is 0.01 [V] and the latter is 0.00
25 [V / min]. Two conditions are AND
Although it is treated as a condition, it can be treated as an OR condition if necessary. If the conditions are satisfied, the process proceeds to step S28, a signal is sent to the charging device 12 (FIG. 2) to perform constant current charging as auxiliary charging, and then the charging is ended. on the other hand,
If the condition is not satisfied in step S27, the charging device 12
A stop signal is sent to, and charging is terminated without performing constant current charging. In this way, each module 101-
If both the voltage of 124 and the rate of change thereof are smaller than a predetermined value, that is, each of the modules 101 to 124
If the battery capacities are substantially uniform, the charging is terminated without further supplementary charging. Therefore, in that case, overcharging does not occur.

A case where the charging method which does not always perform the constant current charging is adopted as in the case of the above-mentioned second embodiment is defined as a case of C,
The characteristics are compared with those of A of Example 1. Figure 7 shows the battery pack 1
Energy efficiency of (Fig. 2) (= (output / input) x 10
It is a graph which shows how 0) changes with an increase in the number of cycles. As is clear from this graph, C
In case of, energy efficiency is several% on average compared to case of A
high. This is because in the case of A, since it is always supplemented by constant current charging, the overcharge amount of the entire assembled battery 1 is large and the energy loss is large, whereas in the case of C, constant current charging is often not performed. Is. However, in the case of C as well, for example, the voltage difference between the modules becomes larger than a predetermined value at a rate of about once every three cycles, and as a result, constant current charging (complementary charging) is performed, so that at that time, the energy is temporarily The efficiency drops to the same level as in the case of A.

FIG. 8 is a graph similar to FIG. 5, showing a change in the traveled distance with respect to the number of cycles. As is clear from FIG. 8, in the case of C, the characteristics are further improved as compared with the case of A. In the case of A, as mentioned above, the initial mileage is almost maintained up to about 200 cycles,
When the number of cycles further increases, the number of cycles starts to gradually decrease, and when the number of cycles reaches 600, the mileage sharply decreases. But C
In the case of, even if the number of cycles reaches 600, the traveling distance of about 70 to 80% of the initial state is still maintained. In the case of C, the number of times constant current charging (complementary charging) is performed is A
This is because the battery deterioration is slower than in the case of.
In the initial stage where the number of cycles is small, the traveling distance in A is often slightly larger than that in C. This is because the constant current charging is always performed in the case of A, whereas the constant current charging is performed in the case of C only under the predetermined condition, and thus a slight difference occurs in the battery capacity.

(Third Embodiment) Next, a third embodiment will be described. Figure 9 shows a normal battery that has not deteriorated yet.
It is a graph which shows the relationship between battery temperature and the voltage value between terminals of the assembled battery 1 (FIG. 2) at the time of constant current charge (complementary charge) in a charge period. As described above, the voltage of the normal assembled battery 1 after the start of the second charging period has a substantially predetermined value according to the battery temperature. Therefore, it is possible to set a reference voltage that is what voltage the voltage of the assembled battery 1 should be for a certain battery temperature. Therefore, reference voltages for various battery temperatures are stored in the ROM 9 (FIG. 2) in advance. FIG. 10 is a graph showing changes in the voltage shift with respect to the number of cycles in each of the case A, the case C, and the case B described above. Here, the voltage shift means a shift (shift of +, that is, increase) from the reference voltage of the assembled battery 1 with respect to the battery temperature at that time, which is determined by the characteristics of FIG. As is clear from FIG. 10, in the case of B, the deviation of the voltage rapidly increases as the number of cycles increases. This is because the internal resistance is rapidly increasing due to the rapid deterioration of the battery. On the other hand, in the case of A, the number of cycles is 400
The deviation of the voltage increases sharply from the time when the voltage exceeds the limit. In the case of C, the increase in the voltage shift is very slow, but it slightly increases in the vicinity of 600 cycles. In this way, the deterioration of the battery can be known by detecting how much the voltage at the time of supplementary charging deviates from the reference value. The following method controls the charging with this in mind.

FIG. 11 is a flowchart showing a charge control method in the third embodiment. Since the circuit configuration is the same as that of the first embodiment shown in FIG. 2, its description is omitted.
In addition, steps S31 to S35 of FIG.
Since it is the same as steps S11 to S15, the description thereof will be omitted. In FIG. 11, when a signal is sent to the charging device 12 (FIG. 2) in step S35 to start constant current charging (complementary charging), the voltage V of the assembled battery 1 is read in the next step S36, and The reference voltage V _ref at the time of supplementary charging corresponding to the battery temperature T is read. Next, in step S37, the value of V- _Vref is obtained, and it is determined whether or not it is less than or equal to a predetermined value. If it is less than or equal to the predetermined value, the process proceeds to step S38, the constant current charging is continued as it is, and then the charging is ended. On the other hand, if the value exceeds the predetermined value in step S37, the process proceeds to step S39, a signal is sent to the charging device 12 to stop charging, and an alarm output is sent to the display device 11 (FIG. 2). The reason for exceeding the predetermined value is that the internal resistance increases as the capacity of the battery decreases (deteriorates), and the voltage during charging increases. The method of stopping charging as described above is performed by each of the modules 101 to 1 constituting the assembled battery 1.
24 (FIG. 2) is particularly effective when the deterioration progresses uniformly as a whole. This is because when the assembled battery 1 is uniformly deteriorated as a whole, the voltage difference between the modules does not increase, and it is difficult to detect the deterioration of the battery even if the increase in the voltage difference is monitored.

Although the above-mentioned Examples 1 to 3 have been described with respect to the assembled battery composed of the assembly of the sealed nickel-hydrogen storage battery as the object of charge control, the method and apparatus of the present invention are not necessarily limited to this. It is also applicable to an assembled battery composed of an assembly such as a lead storage battery or a nickel-cadmium storage battery.

[0031]

The charge control method and the charge control device for an assembled battery according to the present invention configured as described above have the following effects.

In the charge control method for the assembled battery according to the first aspect, first, the assembled battery is mainly charged under the first condition, and then the battery temperature of the assembled battery is detected.
The remaining capacity and the capacity reference value corresponding to the battery temperature are obtained, and when the remaining capacity reaches the capacity reference value, the charging current is reduced to perform supplementary charging under the second condition. Switching to auxiliary charging is performed based on the appropriate capacity reference value. Therefore, the situation in which the amount of charge due to supplementary charging is too large and the battery is significantly overcharged does not occur, so that the deterioration of the battery is delayed and the life of the battery can be extended.

Further, in the charge control method for the assembled battery according to the second aspect, the voltage between both ends of each of the module batteries and the change rate of the voltage are obtained, and the voltage when the remaining capacity reaches the capacity reference value is calculated. When at least one of the inter-module disparity and the inter-module disparity of the voltage change rate exceeds a predetermined value, the charging current is reduced to perform supplementary charging under the second condition, and when it does not exceed the predetermined value, the charging is terminated. As a result, when the voltage variation of the module battery is small, the auxiliary charging is not intentionally performed. Therefore, the overcharge is less likely to occur, and the deterioration of the battery is delayed to prolong the service life.

Further, in the charge control method for the assembled battery according to the third aspect, after starting the auxiliary charging, the voltage across the assembled battery and the voltage reference value during the auxiliary charging corresponding to the battery temperature are read, and the difference between them is read. If the value is less than or equal to the predetermined value, supplementary charging is continued, and if it exceeds the predetermined value, supplementary charging is stopped and an alarm output is issued. This can be quickly detected and notified, and unnecessary use of supplementary charging can be avoided.

Further, in the charge control device for the assembled battery according to the fourth aspect, the battery capacity measuring means integrates the current detected by the current detecting means by time to add or subtract the initial value of the battery capacity of the assembled battery. The remaining capacity of the battery capacity is obtained, and when the remaining capacity reaches the capacity reference value corresponding to the battery temperature of the assembled battery, the charging current is reduced and auxiliary charging is started. Therefore, the charging condition is switched based on the battery capacity in consideration of the battery temperature, and a situation in which the amount of charge by supplementary charging is too large and the battery is significantly overcharged does not occur. As a result, the deterioration of the battery is delayed and the life of the battery can be extended.

Further, in the battery pack charge control device according to the present invention, the battery capacity measuring means integrates the current detected by the current detecting means by time to add or subtract the initial value of the battery capacity of the assembled battery. When the remaining capacity of the battery capacity is calculated and the remaining capacity reaches the capacity reference value corresponding to the battery temperature, the charging current is reduced if at least one of the difference between the modules of the voltage and the rate of change of the voltage exceeds a predetermined value. Then, the auxiliary charging is performed, and if the predetermined value is not exceeded, the charging is immediately terminated. As a result, when the voltage variation of the module battery is small, the supplementary charging is not intentionally performed. Therefore, the overcharge is less likely to occur, and the deterioration of the battery is delayed to prolong the service life.

Further, in the charge control device for the assembled battery according to the sixth aspect, when the remaining capacity of the assembled battery reaches the capacity reference value corresponding to the battery temperature at that time by the main charging, the charging current is reduced to further perform the supplementary charging. On the other hand, the difference between the voltage of the assembled battery and the voltage reference value at the time of supplementary charging with respect to the battery temperature is compared with a predetermined value, and if the difference exceeds the predetermined value, supplementary charging is stopped.
Therefore, when the battery is deteriorated and the internal resistance is increased, the fact can be detected and notified promptly, and useless auxiliary charging is not required.

[Brief description of drawings]

FIG. 1 is a diagram showing an internal circuit configuration of an assembled battery.

FIG. 2 is a block circuit diagram showing a schematic configuration of a battery pack charge control device according to the present invention.

FIG. 3 is a flowchart showing a charge control method according to the first embodiment of the present invention.

FIG. 4 is a graph showing the original upper limit value of the battery capacity corresponding to the battery temperature of the assembled battery.

FIG. 5 is a graph showing how the traveling (possible) distance after charging of an electric vehicle equipped with an assembled battery changes with an increase in the number of cycles for Example 1.

FIG. 6 is a flowchart showing a charge control method according to the second embodiment of the present invention.

FIG. 7 is a graph showing how the energy efficiency of the assembled battery changes with an increase in the number of cycles in Example 2.

FIG. 8 is a graph showing how the traveling (possible) distance after charging of an electric vehicle equipped with an assembled battery changes with an increase in the number of cycles in Examples 1 and 2.

FIG. 9 is a graph showing the relationship between battery temperature and voltage during supplementary charging.

10 is a graph showing how the deviation from the voltage shown in FIG. 9 changes as the number of cycles increases.

FIG. 11 is a flowchart showing a charge control method according to the third embodiment of the present invention.

FIG. 12 shows the battery temperature T, the battery voltage V, the charging current I, and the battery temperature in the case of adopting a two-stage charging method having a second charging period T2 that is a supplementary charging by changing the charging condition after the first charging period T1. It is a graph which shows the characteristic of rate of change dT / dt.

[Explanation of symbols]

 1 assembled battery 2 temperature sensor 3 current sensor 4 voltage sensor 7 A / D converter 8 CPU 9 ROM 10 charging control circuit 12 charging device 101-124 module 201-224 voltage detection circuit

 ─────────────────────────────────────────────────── ─── Continued front page (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 (6)

[Claims] 1. A charging control method for an assembled battery comprising an assembly of a plurality of storage batteries, the main charging being performed on the assembled battery under a first condition, and detecting a battery temperature of the assembled battery. Then, regarding the assembled battery,
Determining the remaining capacity and a capacity reference value corresponding to the battery temperature; reducing the charging current when the remaining capacity reaches the capacity reference value, and performing supplementary charging under the second condition. A charging control method for an assembled battery, comprising: 2. A charging control method for an assembled battery comprising a group of modular batteries formed by connecting a plurality of storage batteries in series, the main charging being performed on the assembled battery under a first condition. , Detecting the battery temperature of the assembled battery, for the assembled battery,
Obtaining the remaining capacity and a capacity reference value corresponding to the battery temperature, and determining the voltage between both ends of each of the module batteries and the rate of change of the voltage, and the remaining capacity is the capacity reference value. When at least one of the inter-module difference in the voltage and the inter-module difference in the rate of change of the voltage exceeds a predetermined value, the charging current is reduced to perform supplementary charging under the second condition, A method of controlling charging of an assembled battery, comprising: terminating charging when the value does not exceed a value. 3. After the step of performing the supplementary charge, the voltage across the assembled battery and the voltage reference value during supplementary charging corresponding to the battery temperature are read. 2. The method of charging an assembled battery according to claim 1, further comprising the step of continuing charging, stopping supplementary charging if a predetermined value is exceeded, and issuing an alarm output. 4. A charge control device for an assembled battery composed of an assembly of a plurality of storage batteries, comprising: current detection means for detecting a charge / discharge current of the assembled battery; and current detected by the current detection means. A battery capacity measuring unit for calculating a remaining capacity of the battery capacity by adding and subtracting an integral value to the initial value of the battery capacity of the assembled battery; a battery temperature detecting unit for detecting a battery temperature of the assembled battery; Judgment means for producing a predetermined output when the capacity reaches a capacity reference value corresponding to the battery temperature, and is connected to both ends of the assembled battery for charging, and receives the output to reduce the charging current and supplementary charge A charging control device for an assembled battery, comprising: 5. A charging control device for an assembled battery comprising a series assembly of a plurality of module batteries, the current detection means detecting a charging / discharging current of the assembled battery, and the current detection means detecting the current. A battery capacity measuring unit that calculates a remaining capacity of the battery capacity by adding and subtracting an initial value of the battery capacity of the assembled battery by integrating the current with time; and a battery temperature detection unit that detects a battery temperature of the assembled battery, Voltage detection means for detecting a voltage across each of the plurality of module batteries; and, when the remaining capacity reaches a capacity reference value corresponding to a battery temperature, an inter-module difference in the voltage and a change rate of the voltage. If at least one of the two exceeds a predetermined value, the first signal is generated, and if it is not exceeded, a second signal is generated. And a charging device that performs supplementary charging while reducing the charging current when receiving the first signal and terminates charging when receiving the second signal. Charge control device. 6. A charge control device for an assembled battery comprising a series assembly of a plurality of module batteries, the current detection means detecting a charge / discharge current of the assembled battery, and the current detection means. A battery capacity measuring means for obtaining a remaining capacity of the battery capacity by adding and subtracting an initial value of the battery capacity of the assembled battery by integrating the current with time; and a voltage detecting means for detecting a voltage between both ends of the assembled battery. A battery temperature detecting means for detecting a battery temperature of the assembled battery; and comparing the remaining capacity with a capacity reference value corresponding to the battery temperature, and when the remaining capacity reaches the capacity reference value, a first signal A capacity comparison means for outputting the voltage, and a voltage comparison means for comparing the difference between the voltage and a voltage reference value with respect to the battery temperature with a predetermined value, and outputting a second signal if the difference exceeds a predetermined value, Both of the battery pack A charging device that is connected to the battery for charging, starts supplementary charging with a reduced charging current when receiving the first signal, and stops charging when receiving the second signal. A battery pack charge control device characterized by the above.