JPH10210666A - Charge control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent errors from being accumulated, even if the charge and discharge are performed repeatedly many times, so as to raise the accuracy in computation of the residual capacity of a battery by changing the operation method of the residual capacity of the battery, according to the finished condition of the charge. SOLUTION: A replaceable battery unit 12 and a battery management device 14 are incorporated into a battery case 10, and a chargeable secondary battery 16 such as a nickel-cadmium battery or the like is accommodated in the battery unit 12. Moreover, the battery management device 14 has a CPU 26 and a nonvolatile memory 28, and in the memory 28, various data used for operation of CPU 26 are stored, and in addition to the battery capacity, the history of the battery 16, and others being data in the middle of operation or the operation results are stored. Then, in the case when the finished mode of the charge is steady, the deterioration coefficient is read out of the memory 28, and the charge capacity is obtained by charge capacity reset method. When it is not steady, it is obtained by current integrating method. As a result, computation errors do not accumulate in the case when the charge and discharge are repeated, and the accuracy in computation of capacity can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control method for a secondary battery represented by a nickel-cadmium battery, a nickel-metal hydride battery, and the like.

[0002]

2. Description of the Related Art In a rechargeable secondary battery, the remaining capacity (battery capacity) of the battery is determined as accurately as possible, and this remaining capacity is displayed as necessary. In this case, the remaining capacity of the battery is obtained by integrating the amount of charge (Ah, ampere hours) and the amount of discharge separately, and calculating the difference between the amount of charge and the amount of discharge. be able to. Since this method integrates the amount of electricity (ampere hours), it is hereinafter referred to as a current integration method.

[0003]

In the current integration method, various corrections are made in order to improve the calculation accuracy. For example, this correction is performed on the amount of charged electricity in consideration of the fact that the charging efficiency changes depending on the temperature during charging and discharging (average temperature) and the amount of charged electricity (battery capacity). Further, at the time of discharging, since the total amount of electricity that can be taken out of the battery changes depending on the discharge current, this correction is performed on the amount of discharged electricity.

However, it is extremely difficult to make a complete correction in various usage environments of a battery. In this current integration method, an error between the actual remaining capacity (battery capacity) and the integrated value capacity obtained by integration is accumulated and increased by repeating charge and discharge. For this reason, there is a problem that accuracy is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and the above-described error is not accumulated even when charging and discharging are repeated many times, and the remaining capacity (battery capacity) of the battery is reduced. It is an object of the present invention to provide a charge control method capable of improving calculation accuracy.

[0006]

According to the present invention, there is provided a charge control method for charging a battery with a battery management device for managing a charge / discharge state, wherein a method for calculating a battery capacity is changed depending on a charge end state. Charging control method.

[0007] When the charging end mode is normal, for example,-△
When charging is terminated by V detection, dT / dt detection, battery temperature upper limit detection, or the like, it is preferable to obtain the battery capacity (remaining capacity) by the charge capacity reset method, and in other cases, to obtain the current capacity by the current integration method. Here, the charge capacity reset method means that the initial capacity C _{O of the} battery (the maximum battery capacity that can be charged in a new state) is determined by the deterioration coefficient K and the charge correction coefficient α of the battery.
And the battery capacity C _D = C _O × K × α. Here, α is a coefficient determined by the battery temperature and the charging current value during charging.

[0008] Further, the method of terminating the charging of-△ V detection is as follows.
This method uses the fact that the battery voltage drops from the maximum value at the end of charging and uses the point in time when the voltage drops by ΔV from the maximum voltage as the charging end point. The method of terminating the charging of the dT / dt detection is based on the fact that the rate of change (dT / dt) of the battery temperature T suddenly increases at the end of charging, and ends when the rate of change reaches a certain level or more. It is. The method of terminating charging by detecting the battery temperature upper limit is a method of terminating charging when the temperature at the end of charging reaches a certain (upper limit).

According to the current integration method, even in the overcharge region, the battery capacity obtained for integrating the current amount may exceed the value (C _O · K) of (initial capacity C _O × deterioration coefficient K). Therefore, in this case, the actual battery capacity C _D can be obtained by using this value (C _O · K).

[0010]

FIG. 1 is a conceptual diagram of one embodiment of the present invention, FIG. 2 is a diagram showing functions of a charging mode, FIG. 3 is a basic operation flow diagram of a charging mode, and FIG. 5
FIG. 6 is a flowchart of an operation for quick charging, and FIG. 6 is a flowchart of an operation for determining a battery capacity. FIG. 7 is a flowchart for determining the deterioration coefficient K, and FIG. 8 is a correction coefficient α for the charging efficiency used for current integration.
₁ and α ₂ , FIG. 9 shows a −ΔV correction coefficient β used in the reset method, and FIG. 10 shows a temperature upper limit correction coefficient γ
FIG. 11 is a diagram showing the dT / dt correction coefficient in the same manner. FIG. 12 is a flowchart of the charging mode entire interrupt operation. Table 1 also shows the capacity determination method for each charging termination mode in the flowchart.

First, the configuration of a battery provided with a battery management device will be described with reference to FIG. In this figure, reference numeral 10 denotes a battery case, in which a replaceable battery unit 12 and
The battery management device 14 is incorporated. Battery unit 1
2 houses a rechargeable secondary battery 16 such as a nickel-cadmium battery.

The positive terminal of the battery 16 is connected to the battery management device 14
Are connected to the positive poles of the charging connector 20 and the discharging connector 22 via the current detecting shunt resistor 18 in the inside.
The negative pole of the battery 16 is connected to the negative pole of the connector 20 of the charger and the negative pole of the discharge connector 22. A charger (not shown) is connected to the charging connector 20, and a load such as an electric motor is connected to the discharging connector 22. A thermistor 24 for detecting battery temperature is attached to the battery 16.

The battery management device 14 includes a CPU (microcomputer) 26 and an EEPROM (Electrically Erase).
ble / Programmable Read Only Memory). The CPU 26 has a shunt resistor 1
8, the charging / discharging current I of the battery 16, the battery voltage V,
Various information is input in addition to the battery temperature T detected by the thermistor 24. For example, a command from a charger or a load, data indicating an operation state, and the like are input.

The memory 28 stores various data used for the operation of the CPU 26. For example, data indicating the type and characteristics of the battery 16, various correction data as shown in FIGS. 9 to 12, and mathematical formulas for calculating the capacity values shown in Table 1 are stored. The memory 28 stores data during the calculation and the battery capacity (remaining capacity) as the calculation result.
Also, the history of the battery 16 and the like are stored.

The CPU 26 uses the data in the memory 28 to measure the battery temperature T, manage the battery capacity,
It performs charging control and the like. Also, the calculation result of the battery capacity is displayed on a display device (not shown), and the deterioration or abnormality of the battery 16 is displayed (battery monitor).

[0016]

[Overview of Overall Charging Operation] Next, the flow of the entire charging mode operation will be described with reference to FIGS. The CPU 26 always waits for various commands from the charger or the load side, and judges the contents when the commands are received (judgment mode, step 100). If this command is for charging (step 102), preparation for charging is started (step 1).
04).

In this preparation for charging, as shown in FIG.
First, it is determined whether or not charging is necessary (step 104).
A). This is to prevent the charging from being performed when the amount of discharge is small, because the memory effect occurs when the shallow charge / discharge is repeated, and the battery deteriorates due to the rise in the battery temperature and the internal pressure at the end of charging. . In this case, only the LED indicating that the battery is being charged is turned on for a certain period of time to give the operator a sense of security. That is, a false charging mode is entered (step 104B).

If charging is required (step 104)
A), it is determined whether or not the battery voltage V is too low, that is, whether or not the battery is overdischarged (step 104C). If the voltage V is too low, preliminary charging is performed (step 104D). For example, rating 2
If the battery 16 is 4 V, the pre-charge is performed when the voltage is 16 V or less.

In this pre-charging, charging is performed with a current (for example, 0.5 amp) sufficiently smaller than the rated capacity of the battery 16 (for example, 5000 mAh at an hourly rate), and the voltage V becomes a predetermined value (for example, 0.5 amp) within a predetermined time. When the voltage is recovered to 16 V) or more, the pre-charging is terminated and the operation returns to the normal charging mode. If the voltage does not recover to a predetermined value (16 V) or more even if the pre-charging is continued for a certain period of time or longer, it is determined that there is an abnormality in the battery due to a short circuit between cells in the battery 16. Display and stop charging.

When pre-charging is not required (step 104)
C) or when the voltage V is recovered by pre-charging (step 104D), it is determined whether or not the battery temperature T is within a chargeable temperature range (charging start temperature range) (step 104E). This temperature range is, for example, O <T <
The temperature may be fixed at 40 ° C., or may be changed depending on the battery capacity (remaining capacity). For example, the upper limit temperature (40 ° C.) of this range can be lowered as the remaining capacity increases.

If the battery temperature T is outside the chargeable temperature range, the process waits without starting charging (step 104).
F) If the value falls within this range, the operation for determining the next charging rate (current) is started (step 104G). This charge rate is determined by determining whether or not the current I immediately after the start of charging is equal to or greater than a predetermined value I _{O, and} if I <I _O , select normal charge (standard charge) (step 106), and if I> I _O A quick charge is selected (step 108). Here, normal charging is a method of charging for a long time with a relatively small current (for example, 1.5 amps), and rapid charging is a method of charging for a short time with a relatively large current (for example, 5 amps).

[0022]

[Normal Charging] In normal charging (step 106), charging is started at a predetermined current (1.5 amps), and a charge ending condition is set. As the charge termination condition, for example, a −ΔV detection method for detecting that the battery voltage V decreases after reaching the maximum value at the end of charging and a timer method set to, for example, 4.5 hours can be used together. .

When entering the normal charging mode (step 106), the battery capacity is first determined as shown in FIG. 4 (step 106A). In this calculation “capacity integration 1”, the charge amount is obtained by adding the charge amount for each charge of a fixed charge amount (for example, 100 mAh) or for a fixed time. At this time, the charging efficiency α defined by the ratio of (accumulated electricity amount) / (charging electricity amount) changes depending on the temperature (average temperature) T of the battery and the battery capacity. _The amount of charged electricity (accumulated amount of electricity) CD that is actually accumulated in the battery 16 by integrating it with _D is determined.

Here, the charging efficiency α is, as shown in FIG. 8, the case of standard charging (normal charging) with a small charging current (α ₁ ).
And rapid charging (α ₂ ) with a large charging current. Therefore, the normal charging mode shown in FIG.
In 6), calculation is performed using the charging efficiency α ₁ shown in Map 1 in FIG.

In this manner, the battery capacity C _D is obtained for each fixed charge amount or for each fixed time, and the voltage V is monitored (step 106B). If V> 40, it is determined that the battery 16 has deteriorated and charging is performed. Stop (step 106
C), calculates the battery capacity C _D by the current integration method (step 106D). This calculation "capacity determination 4"
This is performed according to the determination method shown in No. 4. That is obtained by correcting the capacitance C _D found in step 106A described above. Then, the battery deterioration is displayed (Step 106E), and the process returns to the determination mode (Step 100 in FIGS. 2 and 3).

If the voltage V is equal to or lower than the upper limit voltage (for example, 40 V) and is normal in step 106B, it is determined whether or not the normal charging end condition (-ΔV) is satisfied (step 106F). Once this end condition, as is appropriate charging ends (step 106G), to calculate the capacitance C _D by the reset mode (step 106H). This calculation “capacity determination 1” is performed by the calculation formula shown in No. 1 of Table 1.

[0027]

[Table 1]

That is, the deterioration coefficient K of the battery and the -ｍｉｎVminT correction coefficient β ₁ are integrated into the initial capacity C _O of the battery. Here, the initial capacity C _O is the capacity of the new battery 16 (for example, 5000 mAh). Deterioration coefficient K is a value obtained by dividing the amount of electricity discharged from the fully charged state to the discharge end voltage (referred to as the discharge amount) Ca by the initial capacity C _O ,
That is, K = Ca / _CO .

This deterioration coefficient is updated according to the procedure shown in FIG. To summarize this procedure, the amount of discharge (starting discharge amount Ca) until the battery fully charged by normal charging is completely discharged is determined. When the self-discharge amount up to the complete discharge is 20% or less of the whole, This discharge amount is adopted as the discharge amount Ca suitable for updating the deterioration coefficient K, and the deterioration coefficient K is obtained.

This procedure will be described with reference to FIG. First, when the discharge mode is entered (Step 110), the discharge amount is integrated (Step 110A), and at every predetermined time (Step 110B) or at a predetermined discharge amount (Step 110C, for example, 100 mA).
h), the discharge amount is corrected (step 110D). The above operation is repeated until the end of the discharge is determined (step 110E). If the discharge end voltage is not detected at the end of the discharge (step 110F), the process returns to the determination mode 100 without correcting the deterioration coefficient K.

When the discharge end voltage is detected at the end of the discharge (step 110F), the operation enters the deterioration coefficient determination mode (step 110G). That is, if the amount of self-discharge during this discharge is not sufficiently small (step 110H, for example, when it is 20% or less of the total amount of discharge), it is confirmed that the battery is completely charged before this discharge (step 110I).
The deterioration coefficient K is updated (step 110J). That is, using the complete discharge amount Ca obtained in step 110A, K
= Ca / C _O , which is taken as the latest deterioration coefficient.

-△ Vmi used in the calculation of “capacity determination 1”
FIG. 9 shows the nT correction coefficient β ₁ . Since the battery temperature T is reduced once by the endothermic reaction during charging, the correction coefficient β ₁ is detected by detecting the lowest attained temperature minT.
It shows the correction ratio of the charging efficiency with respect to T. Note that the correction coefficient β includes a case of normal charging with a small charging current I (β ₁ ) and a case of rapid charging with a large charging current (β ₂ )
And the corresponding coefficient β ₁ or β _{2 in} each case
We use properly. In the calculation of “capacity determination 1”, the coefficient β ₁ is used because the charge is normal.

When the calculation of the battery capacity by the charge capacity reset method is completed in this way (step 106 in FIG. 4).
H), and then perform trickle charging (step 106)
I). This trickle charge is a charge for a long time (for example, 8 hours) with a small current (for example, 0.1 A) after the complete charge in step 106H, and adds a charge amount enough to compensate for the self-discharge of the battery. Here, the minute current is a pulse current obtained by intermittently changing the pre-charging current (for example, 0.5 A) to a current corresponding to a desired current (0.1 A), thereby simplifying the circuit of the charger. Is also possible.

If the set time of the timer (for example, 4.5 hours) elapses before the amount of decrease of the voltage V from the maximum value at step 106F reaches -ΔV (step 106J), charging is stopped (step 106K). ), The battery capacity is calculated by the current integration method (step 106L). This calculation is shown in FIG. 4 as “capacity determination 2”, and the method is shown in No. 2 of Table 1. That is, step 1
Determined by correcting the capacitance determined by the "capacity integrated 1" (charged amount C _D obtained by integrating the charge amount for each predetermined charge amount or every predetermined time) 06A. The correction amount in this case is the amount of electricity charged after the predetermined amount of charge has been added immediately before and until the timer reaches the set time and stops charging.

The normal charging shown in FIG. 4 (step 10)
During 6), an interrupt for detecting the temperature of the battery in a timely manner is performed (step 112). In this interrupt, a change in the battery temperature T is monitored, and when the lowest temperature is detected, this is stored as minT (step 112A).
This minT is used when obtaining the −ΔV correction coefficient β described in FIG. This minT is the temperature upper limit correction coefficient γ or dT / dt used in FIGS.
It is also used when obtaining the correction coefficient δ and the like.

When the detected battery temperature reaches the maximum chargeable temperature (for example, 45 ° C.) (step 112)
B), the charging is stopped (step 112C), and the capacity is calculated by the charging capacity reset method of “capacity determination 3” (step 112D). This calculation is performed by the method shown in No. 3 of Table 1. That is, the initial capacity C _O and the deterioration coefficient K
And the temperature upper limit correction coefficient γ (C _O · K · γ).

Here, the temperature upper limit correction coefficient γ is a function of minT as shown in FIG. 10, and is introduced in consideration of the fact that the higher the minT, the shorter the time required to reach the upper limit temperature and the smaller the amount of charge. It was done. Since this coefficient γ also changes depending on the magnitude of the charging current I, the coefficient γ ₁ during normal charging and the coefficient γ ₂ during rapid charging are separately shown.

[0038]

[Quick charging] When quick charging is selected in step 104G of FIG. 3, the charging is started (step 108) shown in FIG. 5 and the conditions for terminating charging are set. As the charge termination condition, for example, dT / dt, −ΔV, a timer method, and the like are possible, and a set value for each method is set.

When rapid charging is started (step 108), the battery capacity is first determined as shown in FIG. 5 (step 108).
D). This calculation is shown as “capacity integration 2” in FIG. 5, but this calculation is based on the normal charge (step 106 in FIG. 4).
Is substantially the same as “capacity integration 1” in

[0040] That is actually battery by seeking charged electricity quantity C _D by adding therebetween charge electrical quantity in a certain amount of charge for each (or every fixed time), integrates the charging efficiency alpha ₂ thereto and requests the quantity of charged electricity C _D to be charged. Charging efficiency alpha ₂ used here are shown in the map 2 rapid charging shown in FIG.

[0041] While determining the battery capacity C _D during charging in this manner, to monitor the battery voltage V (step 108E),
V> 40 If stops charging as the battery 16 has deteriorated (step 108F), calculates the battery capacity C _D by the current integration method (step 108G). This operation "capacity determination 9", as shown in No.9 in Table 1, determined by correcting the capacitance C _D found in step 108D. Then, the battery deterioration is displayed (step 108).
H), and return to the determination mode (step 100 in FIG. 2).

If the voltage V is equal to or lower than the upper limit voltage (for example, 40 V) and is normal in step 108E, dT / dt (time increase rate of the battery temperature T), which is one of the conditions for terminating the rapid charging, becomes higher than a set value. It is determined whether or not it has become (step 108I). If dT / dt is equal to or greater than the set value, it is determined that charging is normally completed and charging is stopped (step 108J).
The capacitance _CD is calculated by the reset method (step 10).
8K). This calculation “capacity determination 5” is performed by the calculation formula shown in No. 5 of Table 1.

That is, the capacity C _D is the initial capacity C of the battery.
_It is determined by the product (C _O · K · δ) of _O , the battery deterioration coefficient K, and the dT / dt correction coefficient δ. Here, the initial capacity C _O and the deterioration coefficient K are the same as those used in the ordinary charging. As shown in FIG. 11, the dT / dt correction coefficient δ is introduced in consideration of the fact that the amount of electricity actually stored changes depending on minT.

As described above, the capacitance C by the reset method
_When the calculation of _D is completed (step 108K in FIG. 5), trickle charging is further performed to replenish the charge (step 1).
08L). And the judgment mode (FIG. 2, step 100)
Return to and wait for the next command.

If the amount of decrease in voltage V from the maximum value reaches the set value of -ΔV before dT / dt reaches the set value in step 108I (step 108M), charging is stopped (step 108M). 108N), the capacity is calculated by the reset method (step 108O). This calculation "capacity calculation 6", as shown in No.6 of Table 1, C _O · K ·
(− △ V correction coefficient β ₂ ). Where-△ V
The correction coefficient β ₂ is set for quick charging as shown in FIG. Then, trickle charging (step 108L) is performed, and the process returns to the determination mode (step 100).

If the set time of the timer (for example, 1.5 hours) elapses before the amount of decrease in voltage V from the maximum value reaches the set value of -ΔV in step 108M (step 108M).
P), charging is stopped (Step 108Q), and the capacity is calculated by the current integration method (Step 108R). This calculation “Capacity calculation 7” is shown in No. 7 of Table 1. That is, the capacity is obtained by correcting the capacity obtained in the “capacity integration 2” in step 108D. The correction amount in this case is the amount of electricity charged from the time when the predetermined amount of charge was added immediately before the time of the timer expires.

Note that the quick charge shown in FIG.
In 8), a battery temperature detection interrupt is performed at an appropriate time. This operation corresponds to the temperature detection interrupt shown in FIG.
12), the same operations are denoted by the same reference characters and description thereof will not be repeated (steps 112A to 112).
C). The difference is the operation of capacity calculation (step 112E).
Only. In the calculation “capacity determination 8” (step 112E), the only difference is the temperature upper limit correction coefficient γ (FIG. 10) used in “capacity determination 3” and (step 112D) in FIG. That using a temperature upper limit correction coefficient gamma ₂ for fast charging here.

[0048]

To summarize the operation of determining the intricate capacitance C _D of the above [Summary of Overall Operation], it is as shown in FIG. In this capacity value determination mode (step 200), it is determined whether the charging end mode is stationary or non-stationary (step 2).
02), in the case of a steady termination mode (−ΔV detection, dT / dt
In the detection, the detection of the temperature upper limit), the calculation of the capacitance value is started (step 204). This calculation is performed by resetting the charging capacity.

First, the deterioration coefficient K is read from the memory 28 (step 206), and the charging mode is determined (step 208). That is, it is determined from the charging rate in step 104G in FIG. 3 whether the charging is quick charging or normal charging (standard charging). At the time of normal charging, when charging is terminated by detecting -ΔV (step 210, step 106 in FIG. 4)
F), the capacitance C _{D according} to “capacity determination 1” (C _O · K · β ₁ )
Is obtained (step 212). When the battery temperature T reaches the upper limit (45 ° C.) and the charging is terminated (step 214, step 112B in FIG. 4),
The capacitance C _D is obtained by “capacity determination 3” (C _O · K · γ ₁ ).

When charging is terminated by dT / dt detection during rapid charging (step 218, step 10 in FIG. 5).
8I), the capacitance C _{D according} to “capacity determination 5” (C _O · K · δ)
Is obtained (step 220). When the charging is terminated by the detection of −ΔV (step 222, step 108 in FIG. 5).
M), the capacitance C _{D according} to “capacity determination 6” (C _O · K · β ₂ )
(Step 224). When the battery temperature T reaches the upper limit (45
° if the charging was terminated by reaching the C) (step 226, step 112B of FIG. 5), obtains a capacitance C _D by "capacity determination 8" _{(C O · K · γ 2} ).

[0051] when charging end forms is not constant (when unsteady) (step 202), determining the capacitance C _D by the current integration method (step 230). That is, the charge amount during the predetermined charge amount (100 mAh) or at predetermined time intervals is obtained and added in order. In this case, the correction is made using the charging efficiency α of the battery. At this time, the charging efficiency α ₁ determined by the average battery temperature during a predetermined charge amount (or a predetermined time), the battery capacity at that time, and the magnitude of the charging current,
The α ₂ is used. When the charging is terminated by the expiration of the timer, every predetermined charge amount (or every predetermined time) immediately before
After that, the correction is performed to add the charge amount charged before the timer expires.

[0052]

[Overall Charge Mode Interruption] During the charge operation described above, the charge state is monitored as shown in FIG. That is, when the entire interrupt operation for monitoring starts (step 300), first, the charging current I is checked (step 302). Here, if the charging current I is abnormal (step 304), the charging is terminated (step 306).

That is, the charging LED (light emitting diode indicating the charging state) is turned off for the charger, the output of the charger is turned off, and LE indicating that charging is not completed is performed.
Turn D on. Then, a display indicating that there is a charging abnormality is made on the display device (step 308), and after the capacity value is determined (step 310), the process returns to the determination mode 100 shown in FIGS.

Here, "capacity value determination A" of step 310
Is performed by the method shown in No. 10 of Table 1. That is, during normal charging, the amount of charge that has been charged from the immediately preceding capacity integration to the detection of an abnormality in the charging current in step 304 is compared with the capacity obtained in “capacity integration 1” in step 106A shown in FIG. Make corrections. If rapid charging is being performed, “capacity integration 2” in step 108D shown in FIG. 5 is similarly corrected.

When there is no abnormality in the charging current (step 3
04), a charger connection check is performed (step 31)
2). When the charger is not connected (step 31
4), charging is terminated (step 316). In this case, the same processing as in step 306 is performed, and the discharge prohibition signal is turned off so that discharge is possible. Then, the capacity value is obtained by "capacity value determination B" (step 318). This calculation is performed as shown in No. 11 of Table 1 by "capacity integration 1" (step 106A of FIG. 4) or "capacity integration 2" ( This is for correcting the capacitance value in step 108D) of FIG.

If the charger is connected (step 314), the integrated capacity value is checked (step 330). That is, the calculated capacity value is displayed as a set value to be displayed on the display device (step 3).
32).

[0057]

Other Embodiments In the present invention, other types of charging termination modes suitable for the type of battery used can be used. For example, a lead storage battery can use a V taper control charging method, a constant voltage constant current control charging method, or the like.

[0058]

According to the first aspect of the present invention, as described above, the calculation method of the battery capacity is changed depending on the termination mode of the charge. Therefore, when the charge and discharge are repeated as in the current integration method, the calculation error is reduced. Without being accumulated, the calculation accuracy of the capacity can be improved.

When the charge end mode is normal and the battery is fully charged, the capacity can be obtained by the charge capacity reset method, and at other times, the capacity can be obtained by the current integration method (claims 2 and 4). The normal charging termination mode may be any one of a case where the charging is terminated by detecting -ΔV, detecting dT / dt, and detecting the upper limit of the battery temperature (claim 3).

In the current integration method, the capacity is determined by multiplying the predetermined charge amount by the charge efficiency α with respect to the average temperature and the average battery capacity during the predetermined charge amount and sequentially adding them (claim 5).

It should be noted that the battery capacity determined in this current integration method, in the case of exceeding the value of the product of the initial capacity and deterioration coefficient (C _O · K) is the value (C _O · K) and the battery capacity (Claim 6). Deterioration coefficient K used herein is the ratio of the discharge amount C _D Dashikiri to the initial capacity _{C O1 (C D / C O} )
(Claim 7). Therefore it is preferable to update the deterioration coefficient K in a timely manner using the capacitance C _D of the after suitable full discharge.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one embodiment.

FIG. 2 is a diagram showing functions in a charging mode.

FIG. 3 is a basic operation flowchart of a charging mode.

FIG. 4 is an operation flowchart of ordinary charging.

FIG. 5 is an operation flowchart of quick charging.

FIG. 6 is a flowchart of a battery capacity determination operation.

FIG. 7 is a flowchart of an operation of determining a deterioration coefficient.

FIG. 8 is a diagram showing a charging efficiency correction coefficient α.

FIG. 9 is a diagram showing a −ΔV correction coefficient β;

FIG. 10 is a diagram showing a temperature upper limit correction coefficient γ;

FIG. 11 is a diagram showing a dT / dt correction coefficient δ;

FIG. 12 is a flowchart of a charging mode entire interrupt operation;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Battery case 12 Battery unit 14 Battery management device 16 Battery 26 CPU 28 Memory

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02J 7/10 H02J 7/10 L

Claims (7)

[Claims] 1. A charge control method for charging a battery with a battery management device that manages a charge / discharge state, wherein a method of calculating a battery capacity is changed according to a charge end state. 2. The charge control method according to claim 1, wherein when the charge end state is a normal charge end, the battery capacity is calculated by a charge capacity reset method in which a deterioration coefficient and a charge correction coefficient are added to the initial capacity of the battery. 3. The charge control method according to claim 2, wherein the normal charge termination is when the charge is terminated by detecting -ΔV, dT / dt, and detecting the upper limit of the battery temperature. 4. The charge control method according to claim 2, wherein the battery capacity is calculated by a current integration method for integrating the amount of charged electricity, except when the end of charging is a normal end of charging. 5. The charge control method according to claim 4, wherein in the current integration method, the battery capacity is corrected using a charge efficiency correction map for an average temperature and an average battery capacity during each predetermined charge amount. 6. The battery capacity obtained by the current integration method is as follows:
6. The charge control method according to claim 4, wherein when the value exceeds (initial capacity × deterioration coefficient), this value is used as the battery capacity. 7. A deterioration coefficient K is Dashikiri discharge amount C _D when discharged to a discharge end voltage to the initial capacity C _O of the battery
7. The charge control method according to claim 2, wherein the charge control method is determined by a ratio C _D / C _O.