JPH1014115A - Capacity integration method and battery pack - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To accurately calculate an integrated value of a charged capacity. When the current capacity (the capacity remaining in the battery) (shown by a solid line in FIG. 3A) is equal to or higher than a predetermined reference level and is within a predetermined step width Cph, Neither the reference level (the part shown by the dotted line in FIG. 3A) nor the integrated capacity (the part shown by the solid line in FIG. 3B) is updated. When the current capacity becomes larger than the reference level by a step width Cph or more, both the reference level and the current capacity are incremented by the step width Cph. When the current capacity becomes smaller than the reference level, the reference level is decremented by the unit of the step width Cph until the current level becomes equal to or less than the current capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity integrating method and a battery pack, and more particularly to a capacity integrating method and a battery pack capable of accurately obtaining an integrated value of a charge capacity or a discharge capacity of a secondary battery. About.

[0002]

2. Description of the Related Art Conventionally, the number of times of charge / discharge (cycle), the integrated value of charge capacity or discharge capacity (cumulative value) and the like are used as a guide for knowing the life of a secondary battery.
Since the state of consumption of the secondary battery varies depending on, for example, whether or not charging has been performed since the discharge was completely performed, the number of times of charging and discharging is a measure of the life of the secondary battery.
Not very reliable.

On the other hand, the integrated value of the charge capacity or the discharge capacity (hereinafter, appropriately referred to as the integrated capacity) does not
Therefore, it is preferable to use the integrated capacity as a guide for knowing the life of the secondary battery.

[0004]

By the way, as a method of calculating the integrated capacity, the remaining capacity of the secondary battery (the capacity remaining in the secondary battery) is detected and the change is integrated.
There is a method of determining what Ah (ampere hour) or how many Wh (watt hour) has been charged or discharged. However, the remaining capacity of the secondary battery depends on noise and
Since the detection result may change depending on the charge / discharge rate, and an error may be included in the detection result, a small change considered as an error in the remaining capacity of the secondary battery is integrated, and the integrated capacity becomes There is a problem that the included error becomes large.

[0005] The present invention has been made in view of such a situation, and it is an object of the present invention to obtain an integrated capacity with relatively high accuracy.

[0006]

According to a first aspect of the present invention, there is provided a capacity integrating method for detecting a current capacity of a secondary battery and, when the current capacity has changed by a predetermined step width or more, calculates the integrated capacity by the value. The present invention is characterized in that the current capacity is updated to a value obtained by adding a change equal to or more than a predetermined step width.

According to a ninth aspect of the present invention, there is provided a battery pack for detecting a current capacity of a secondary battery, determining means for determining whether the current capacity has changed by a predetermined step width or more, And an updating unit for updating the integrated capacity to a value obtained by adding a change of the current capacity by a predetermined step width or more to the value when the integrated capacity has changed by more than the predetermined step width.

In the capacity integration method according to the first aspect, the current capacity of the secondary battery is detected, and if the current capacity has changed by a predetermined step width or more, the integrated capacity is replaced by the value of the integrated capacity. The data is updated to a value obtained by adding a change larger than a predetermined step width.

In the battery pack according to the ninth aspect, the detecting means detects the current capacity of the secondary battery, and the determining means determines whether the current capacity has changed by a predetermined step width or more. It has been done. The updating means updates the integrated capacity to a value obtained by adding a change of the current capacity by a predetermined step width or more to the value when the current capacity changes by a predetermined step width or more.

[0010]

FIG. 1 shows the configuration of an embodiment of a personal computer system to which the present invention is applied. This personal computer system is, for example, a portable personal computer (body) 30.
And a battery pack 20 that can be attached to and detached from the personal computer.
It can operate as a power supply.

The battery pack 20 monitors the state of the secondary battery E (for example, the voltage of the secondary battery E, the charge / discharge current, the remaining capacity, etc.), and a charger (not shown) or a personal computer 3
The so-called intelligent battery (Smart Battery (Duracell), which exchanges data (communication) with loads such as 0
Which is proposed by Intel Corp.), for example, and includes a microcomputer (microcomputer) 1 for monitoring a battery. According to such a battery pack 20, the state of the secondary battery E transmitted from the battery pack 20 can be notified to the user on the charger or the load side.

The secondary battery E built in the battery pack 20
Is, for example, a lithium ion secondary battery E,
The terminal is connected to the plus terminal 7 of the pack (package of the battery pack 20), and the minus terminal is connected to the minus terminal (GND terminal) 8 of the pack via the current detection circuit 3 and the switch 2. Have been. Therefore, the discharge current of the secondary battery E flows through the + terminal 2 and the − terminal 8 (the discharge current is supplied to the personal computer 30 through the + terminal 2 and the − terminal 8). Note that, even when the battery pack 20 is charged, the charging current flows through the + terminal 2 and the −terminal 8.

The microcomputer (microcomputer) 1 (detection means) (judgment means) (update means) is, for example, a CPU.
And the like, and periodically receives the output of the current detection circuit 3 or the voltage detection circuit 4, whereby the current (discharge current and charge current) flowing through the secondary battery E or the secondary battery E
(Hereinafter referred to as a battery voltage as appropriate). The microcomputer 1 controls the normally-on switch 2 to be turned off based on the voltage or the current, thereby interrupting the current (charging current or discharging current). ,
Overcharge, overdischarge, and overcurrent are prevented.

The microcomputer 1 obtains (detects) the current remaining capacity of the secondary battery E based on the battery voltage recognized as described above (the detected remaining capacity is hereinafter referred to as the current In addition, an integrated capacity for the charging capacity is calculated based on the current capacity. Further, the microcomputer 1 has a communication terminal 9 of the pack.
, And communicates with the personal computer 30 via the communication terminal 9 according to a predetermined communication procedure. That is, the microcomputer 1 performs a predetermined process according to data (command) transmitted through the communication terminal 9, or performs a battery voltage, a charge / discharge current,
The remaining capacity of the secondary battery E, the accumulated capacity, and the like are transmitted to the personal computer 30 via the communication terminal 9.

Here, regarding the lithium ion battery,
There is a relationship between the battery voltage (open voltage) and the remaining capacity. If the battery voltage is known, the remaining capacity can be obtained. Therefore, the microcomputer 1 determines the remaining capacity of the secondary battery E, which is a lithium ion battery, based on the battery voltage as described above.

The switch 2 performs switching under the control of the microcomputer 1, thereby turning on / off the charging current and the discharging current. Current detection circuit 3
Is a current flowing there, that is, a discharge current of the secondary battery E,
And a charging current for the secondary battery E is detected and supplied to the microcomputer 1. The voltage detection circuit 4
The battery voltage is detected and supplied to the microcomputer 1. The register unit 5 is configured by a register for storing, for example, an integrated capacity, a reference level, a variable at which a minimum capacity value, and a variable at which a maximum capacity value is stored, which will be described later. The display unit 6 (display means) is, for example, a liquid crystal display or the like, and displays integrated capacity and other information under the control of the microcomputer 1. The ROM 10 stores programs and data necessary for the operation of the microcomputer 1. That is, the microcomputer 1 performs various processes by executing the program stored in the ROM 10 while referring to the data stored in the ROM 10 as necessary.

The battery pack 2 configured as described above
When 0 is properly mounted on the personal computer 30, its + terminal 7, − terminal 8, and communication terminal 9 are electrically connected to the personal computer 30. The personal computer 30 is connected to the battery pack 20
In this case, the discharge current of the secondary battery E flows through the path of the + terminal 7, the personal computer 30, and the − terminal 8. The personal computer 30 has a built-in charger,
The battery pack 20 (secondary battery E) can be charged. In this case, the personal computer 30
Charging current from the (charger) is + terminal 7, secondary battery E,
-It flows along the route of terminal 8.

In the battery pack 20, the current detection circuit 3
Alternatively, the current (discharge current, charge current) flowing through the secondary battery E or its battery voltage is detected by the voltage detection circuit 4, and the current value and the voltage value are periodically received by the microcomputer 1. . Then, the microcomputer 1 determines whether the secondary battery E is in the overcharge state, the overdischarge state, or the overcurrent state based on the current value and the voltage value, and determines whether the secondary battery E is in the overcharge state or the overcharge state. When in the discharging state or the overcurrent state, the switch 2 is turned off to interrupt the current (charging current, discharging current).

The microcomputer 1 determines the current capacity (here, as described above, based on the battery voltage of the secondary battery E,
The remaining capacity of the secondary battery E) is calculated, and further, based on the current capacity, the integrated capacity is calculated with reference to the register unit 5 as necessary.

The microcomputer 1 calculates the integrated capacity calculated as described above, the current value supplied from the current detection circuit 3 and the voltage value supplied from the voltage detection circuit 4 in accordance with a request from the personal computer 30. The data is transmitted via the communication terminal 9. Further, the microcomputer 1 supplies the obtained integrated capacity to the display unit 6 for display. The display of the integrated capacity on the display unit 6 can be performed only when necessary (for example, when an operation unit (not shown) is operated).

Next, a method of calculating the integrated capacity of the charging capacity performed by the microcomputer 1 will be described. First, the flowchart of FIG. 2 shows a process of the microcomputer 1 when the integrated capacity is calculated by the first method, and FIG. 3 shows a time change of the reference level at that time (FIG.
(A)) and the time change of the integrated capacity (FIG. 3 (B)).

Here, the reference level is compared with the current capacity so that the change in the current capacity is determined by a predetermined step width C.
This is used for recognizing whether or not the battery level is equal to or more than ph. As the initial value of the reference level, for example, the initial current capacity (before the start of use of the battery pack 20 (at the time of manufacture)) is set. Further, the step width Cph is a value larger than the increase in the current capacity that can be regarded as an error (for example,
10 Wh) and the appropriate step width C
ph can be statistically determined by, for example, an experiment.

The step width Cph is determined in advance by R
The OM 10 may store the value as an unchangeable value, or may store the value in the register unit 5 so that the user can change the value if necessary. It is possible.

In the case of the first method, first, in step S1, the current capacity is detected, and the process proceeds to step S2, where the difference between the current capacity and a predetermined reference level (current capacity-reference level) is calculated. , Predetermined step width C
It is determined whether it is not less than ph (> 0). In step S2, when it is determined that the difference between the current capacity and the reference level is equal to or more than the predetermined step width Cph, that is, the charging is performed, so that the current capacity increases by more than the step width Cph from the reference level. If so, step S
3 and the reference level is changed to the value by the step width Cph.
And the integrated capacity is also updated to the value obtained by adding the step width Cph to the value.
It returns to step S1.

Therefore, when the current capacity is larger than the reference level by the step width Cph or more by charging, the reference level and the integrated capacity are set to the step width Cph (hereinafter, also referred to as one step as appropriate). ) Is incremented.

On the other hand, if it is determined in step S2 that the difference between the current capacity and the reference level is not larger than the predetermined step width Cph, that is, if the current capacity is smaller than the reference level + step width Cph, step S4 To determine whether the current capacity is smaller than the reference level. If it is determined in step S4 that the current capacity is lower than the reference level, that is, if the current capacity has dropped below the reference level due to discharge, the process proceeds to step S5, where the reference level is reduced by one step. It is decremented and returns to step S4. Therefore, in this case, the reference level is decremented by one step until it is determined in step S4 that the current capacity is not smaller than the reference level, that is, until the reference level becomes equal to or less than the current capacity.

If it is determined in step S4 that the current capacity is not smaller than the reference level, that is, if the current capacity is equal to or more than the reference level, the process proceeds to step S4.
1 and the processing from step S1 is repeated again.

Therefore, if the current capacity is equal to or higher than the reference level and is within the range of the step width Cph, the processing of steps S1, S2, and S4 is repeated. Is not updated. Then, the current capacity becomes smaller than the reference level by a step width C.
If it becomes greater than ph, in step S3, both the reference level and the current capacity are incremented by one step. That is, in this case, the reference level or the current capacity is updated to a value obtained by adding the step width Cph to each value. When the current capacity becomes smaller than the reference level, in the processing loop of steps S4 and S5, the reference level is decremented by one step until the current capacity becomes equal to or less than the current capacity. That is, in this case, the reference level is obtained by subtracting a value in the unit of the step width Cph (a minimum value that is a multiple of the step width Cph and is equal to or more than the difference between the current capacity and the reference level before update) from the value. Will be updated to

FIG. 3 shows a temporal change of the reference level (FIG. 3A) and the integrated capacity (FIG. 3B) when the integrated capacity is calculated as described above.

The dotted line in FIG. 3A represents the reference level. The solid line in FIG. 3 (A) represents the time change of the current capacity, and FIG. 3 shows the time change of the reference level and the integrated capacity when the current capacity changes as shown in FIG. 3 (A). Is shown. Furthermore, in FIG. 3, the numbers attached to the vertical axis are for convenience and have no relation to the actual values. The solid line in FIG. 3 (B) indicates the integrated capacity, and the dotted line in FIG. 3 (B) indicates the integrated value (simple integrated value) obtained by simply integrating the increase in the current capacity. ing. The same applies to FIGS. 5, 7, 9, 11, 13, and 15 described later.

In the embodiment shown in FIG. 3, first, the current capacity (FIG. 3 (A)) is increased, and therefore, charging is being performed. In this case, when the current capacity exceeds the current reference level and then becomes larger than the reference level by the step width Cph or more, the process proceeds from step S2 to step S3.
The reference level (FIG. 3A) is increased by the step width Cph, and the integrated capacity (FIG. 3B) is also increased by the step width Cph.

Thereafter, when the charging is completed and the discharging is started, the current capacity (FIG. 3 (A)) is reduced. When the current capacity becomes smaller than the reference level, the reference level is set in steps S4 and S5. (FIG. 3B) is reduced by the value of the step width Cph unit. Then, after the current capacity (FIG. 3A) reaches a predetermined value, charging is started again. As a result, when the current capacity increases by more than the step width Cph from the reference level, as described above, step S2 is performed. From step S3 to the reference level (FIG. 3).
(A)) is increased by the step width Cph,
The integrated capacity (FIG. 3B) is also increased by the step width Cph.

Hereinafter, the integrated capacity is obtained in the same manner.

As described above, when the current capacity is larger than the reference level by the step width Cph or more, the reference level and the integrated capacity are incremented by the step width Cph (one step). When the value becomes smaller, the reference level is reduced in steps of Cph so as to become the largest value equal to or less than the current capacity. Therefore, an increase in the current capacity below Cph, which can be regarded as an error, is ignored. As a result, the integrated capacity can be determined relatively accurately.

By the way, in the case of the first method, even if the current capacity suddenly increases during the detection cycle and becomes much larger than the reference level, the integrated capacity and the reference level are incremented by only one step. Therefore, such a rapid increase in the current capacity may not be able to cope with such a rapid increase in the current capacity (however, such a rapid increase in the current capacity usually does not occur).

In order to cope with such a case, the flowchart of FIG. 4 shows the processing of the microcomputer 1 when the integrated capacity is calculated by the second method.
Indicates a temporal change in the reference level (FIG. 5A) and the integrated capacity (FIG. 5B) at that time.

In the case of the second method, in steps S11 to S13, S15 or S16,
The same processes as those in steps S1 to S3, S4, or S5 in FIG. 2 are performed. After the process in step S13, the process in step S14 may be performed without directly returning to step S11. , Is different from the case according to the first method.

That is, in the case of the second method,
After the process in step S13, the process proceeds to step S14, and it is determined whether the difference between the current capacity and the reference level is equal to or greater than a predetermined step width Cph, as in step S12.

In step S14, when it is determined that the difference between the current capacity and the reference level is equal to or larger than the predetermined step width Cph, that is, in step S13, even if the reference level is incremented by one step, the current level is still present. If the capacity is larger than the reference level by the step width Cph or more, the process returns to step S13 again. Therefore, in this case, the difference between the current capacity and the reference level is the step width Cp
The reference level (including the accumulated capacity) is decremented by one step until h or less.

If it is determined in step S14 that the difference between the current capacity and the reference level is not equal to or larger than the predetermined step width Cph, the process returns to step S11, and the processing from step S11 is repeated again.

Therefore, when the current capacity is equal to or larger than the reference level and is within the range of the step width Cph, neither the reference level nor the current level is updated as in the case of FIG. Also, when the current capacity becomes smaller than the reference level, the reference level is decremented by one step until the current capacity becomes equal to or less than the current capacity as in the case of FIG. When the current capacity becomes larger than the reference level by the step width Cph or more, the step S
In the loop processing of steps S13 and S14, both the reference level and the current capacity are incremented by one step until the difference between the current capacity and the reference level becomes equal to or less than the step width Cph. That is, in this case, the reference level or the current capacity is set to a value corresponding to the step width Cph.
The value is updated to a value obtained by adding a unit value (a multiple of the step width Cph and a maximum value equal to or less than the difference between the current capacity and the reference level before the update).

FIG. 5 shows a temporal change in the reference level (FIG. 5A) and the integrated capacity (FIG. 5B) when the integrated capacity is calculated as described above.

In the embodiment shown in FIG. 5, the current capacity (FIG. 5A) is first increased, and charging is being performed. In this case, when the current capacity exceeds the current reference level and then becomes larger than the reference level by the step width Cph or more, in steps S13 and S14,
The value of the unit of step width Cph is added to the reference level (FIG. 5A), and the value of the unit of step width Cph is also added to the integrated capacity (FIG. 5B).

Thereafter, when the charging is completed and the discharging is started, the current capacity (FIG. 5 (A)) decreases. If the current capacity becomes smaller than the reference level, the reference level is set in steps S15 and S16. (FIG. 5B)
The value of the step width Cph is subtracted. Then, after the current capacity (FIG. 5A) reaches a predetermined value, charging is started again. As a result, when the current capacity increases by more than the step width Cph from the reference level, as described above, step S13 is performed. At S14 and S14, the reference level (FIG. 5)
(A)) is added to the value of the unit of the step width Cph, and the integrated capacity (FIG. 5B) is also added to the step width Cp.
The value in h units is added.

Hereinafter, the accumulated capacity is similarly obtained.

As described above, when the current capacity is larger than the reference level by the step width Cph or more, the reference level and the integrated capacity are incremented in increments of the step width Cph, and the current capacity becomes smaller than the reference level. In this case, the reference level is reduced in units of the step width Cph, so that an increase in the current capacity below Cph, which can be regarded as an error, is ignored, and as a result, the integrated capacity becomes
It can be obtained relatively accurately. Further, it is possible to cope with a sudden increase in the current capacity.

Next, in the case of the first and second methods, when the current capacity becomes smaller than the reference level, the reference level is immediately reduced by the unit of the step width Cph. ) And the second half (right half) of FIG. 5A, when the current capacity fluctuates so as to cross the value that the reference level can take, the reference level is incremented and decremented. Is repeated. According to the first and second methods, since the accumulated capacity is incremented together with the reference level, if the current capacity fluctuates so as to cross the value that the reference level can take, the accumulated capacity becomes a true value. It will be larger than the value.

Therefore, in order to cope with such a case, the flowchart of FIG. 6 shows the processing of the microcomputer 1 when the integrated capacity is calculated by the third method.
Indicates a temporal change of the reference level (FIG. 7A) and the integrated capacity (FIG. 7B) at that time.

In the case of the third method, steps S21 to S23 are performed in step S24 except that processing different from that in step S4 of FIG. 2 is performed.
Alternatively, in S25, the same processing as in steps S1 to S3 or S5 in FIG. 2 is performed.

That is, in the case of the third method,
In step S24, it is determined whether or not the difference between the reference level and the current capacity (reference level-current capacity) is larger than the step width Cph. If it is determined in step S24 that the difference between the reference level and the current capacity is larger than the step width Cph, the process proceeds to step S25, the reference level is decremented by one step, and the process returns to step S24. If it is determined in step S24 that the difference between the reference level and the current capacity is not larger than the step width Cph, the process proceeds to step S2.
Return to 1.

Therefore, according to the third method, when the current capacity becomes larger than the reference level by the step width Cph or more, both the reference level and the current capacity are incremented as in the first method. You. Also,
When the current capacity is within the range of the step width Cph from the reference level (reference level ± Cph), neither the reference level nor the current level is updated. Then, the reference level is decremented only when the current capacity becomes smaller than the step width.

FIG. 7 shows a temporal change in the reference level (FIG. 7A) and the integrated capacity (FIG. 7B) when the integrated capacity is calculated as described above.

In the embodiment shown in FIG. 7, first, the current capacity (FIG. 7A) is increased, and therefore, charging is being performed. In this case, when the current capacity exceeds the current reference level and then becomes larger than the reference level by a step width Cph or more, the process proceeds from step S22 to step S23, and the reference level (FIG. 7A) increases by the step width Cph. At the same time, the integrated capacity (FIG. 7B) is also increased by the step width Cph.

Thereafter, when the charging is completed and the discharging is started, the current capacity (FIG. 7 (A)) decreases. However, when the current capacity becomes smaller than the reference level by a step width or more, in steps S24 and S25. , Reference level (Fig. 7
From (B)), the value in the unit of the step width Cph is subtracted. Then, after the current capacity (FIG. 7A) reaches a predetermined value, charging is started again, whereby the current capacity becomes
When the reference level increases by more than the step width Cph, as described above, the process proceeds from step S22 to step S23, where the reference level (FIG. 7A) is increased by the step width Cph and the integrated capacity (FIG. 7B) ) Is also increased by the step width Cph.

Hereinafter, the accumulated capacity is similarly obtained.

As described above, when the current capacity is larger than the reference level by the step width Cph or more, the reference level and the integrated capacity are incremented by the step width Cph (one step). Therefore, when the step width becomes smaller than the step width Cph, the reference level is decreased in units of the step width Cph. Therefore, the increase in the current capacity below the Cph, which can be regarded as an error, is ignored. Can be determined relatively accurately. Further, as shown in the latter half of FIG. 7A, even when the current capacity fluctuates so as to cross the value that the reference level can take, the integrated capacity is larger than the true value. Can be prevented.

Next, in the case of the third method,
As in the case of the first method, the increment of the integrated capacity and the reference level is performed only for one step when the current capacity is larger than the reference level by a step width Cph or more. When the step width is larger than the step width Cph, as in the case of the second method, the increment of the integrated capacity and the reference level is not limited to one step, but if necessary, an integral multiple thereof (in units of the step width Cph). Value).

The flowchart of FIG.
9 shows the processing of the microcomputer 1 when the integrated capacity is calculated by the method of FIG. 9. FIG. 9 shows a time change of the reference level (FIG. 9 (A)) and the integrated capacity (FIG. 9 (B)) at that time. Is shown.

Incidentally, in the case of the fourth method,
In steps S31 to S34, step S in FIG.
Since the same processing as in the cases of 11 to S14 is performed, and the same processing as in the case of step S24 or S25 in FIG. 6 is performed in step S35 or S36, the details of FIG. 8 and FIG. Detailed description is omitted.

According to the fourth method, the integrated capacity can be obtained relatively accurately, and as shown in the latter half of FIG. 9A, the current capacity crosses a value that can be taken by the reference level. Even if it fluctuates, the accumulated capacity can be prevented from becoming larger than the true value, and it is possible to cope with a sudden increase in the current capacity. Become.

In the first to fourth methods, the reference level is increased or decreased by n steps (where n is 1).
Integer), so the possible values are:
For example, it is a fixed value such as Cph, 2Cph, 3Cph,. When the reference level takes such a fixed value only, the value can be stored in the ROM 10 (FIG. 1), and the necessary reference level can be read by giving an address to the ROM 10. Part 5
Need not be provided with a register for storing the reference level. That is, a rewritable register is generally more expensive and larger in size than a read-only ROM 10, so that a fixed value that can be taken as a reference level is stored in a ROM1.
If the value is stored as 0, the cost and size of the device can be reduced.

However, on the other hand, when the reference level can take only a fixed value, that is, for example, according to the third or fourth method, in the worst case, the current capacity increases and the current level increases by 2 Cph. When it increases near and then decreases, the accumulated capacity may not be incremented at all. That is, in this case, an increase in the current capacity near 2 Cph, which is unlikely to be an error, is not reflected in the integrated capacity, and as a result, the accuracy of the integrated capacity is reduced.

In order to prevent such a situation, the reference level can be set to a variable value. The flowchart of FIG. 10 shows the processing of the microcomputer 1 when the integrated capacity is calculated by the fifth method using a reference level that can take a variable value.
Indicates a temporal change of the reference level (FIG. 11A) and the integrated capacity (FIG. 11B) at that time.

In the case of the fifth method, in steps S41 to S44, the same processes as those in steps S1 to S4 of FIG. 2 are performed. If it is determined in step S44 that the current capacity is smaller than the reference level, that is, if the current capacity is lower than the reference level, the process proceeds to step S45, where the value of the current capacity is copied to the reference level ( The value of the reference level is updated to a value equal to the current capacity), and step S41
Return to

FIG. 11 shows a temporal change in the reference level (FIG. 11A) and the integrated capacity (FIG. 11B) when the integrated capacity is calculated as described above.

In the case where charging is performed, FIG.
When the current capacity exceeds the reference level and then increases by a step width Cph from the reference level, the reference level (FIG. 11A) is increased by one step and the integrated capacity (FIG. 11 (B)) is also increased by one step (step S43).

Thereafter, when the charging is completed and the discharging is started, the current capacity (FIG. 11A) decreases. However, when the current capacity falls below the reference level, the current level (FIG. 11A) decreases.
(A)) also decreases with the current capacity (step S
45). Then, after the current capacity (FIG. 11A) reaches a predetermined value, charging is started again. As a result, when the current capacity becomes larger than the reference level by the step width Cph, as described above, the reference level becomes higher. (FIG. 11B) is 1
As the number of steps is increased, the accumulated capacity (FIG. 11)
(C)) is also increased by one step.

Hereinafter, the integrated capacity is obtained in the same manner.

As described above, when the current capacity is larger than the reference level by the step width Cph, the reference level and the integrated capacity are changed to the step width Cph (one step).
In addition, when the current capacity becomes smaller than the reference level, the reference level is reduced together with the current capacity, so that the increase in the current capacity that can be regarded as an error is ignored, and The increase in the current capacity, which is unlikely to be considered, is taken into account, and as a result, the integrated capacity can be obtained with higher accuracy.

Next, in the case of the fifth method,
As in the case of the first method, the increment of the integrated capacity and the reference level is performed only for one step when the current capacity is larger than the reference level by a step width Cph or more. When the step width is larger than the step width Cph, as in the case of the second method, the increment of the integrated capacity and the reference level is not limited to one step, but if necessary, an integral multiple thereof (in units of the step width Cph). Value).

FIG. 12 is a flow chart showing the operation of the microcomputer 1 when the integrated capacity is calculated by the sixth method.
FIG. 13 shows a temporal change of the reference level (FIG. 13A) and the integrated capacity (FIG. 13B) at that time.

In the case of the sixth method,
In steps S51 to S54, step S in FIG.
11 and S14, and the same processing as that in step S44 or S45 in FIG. 10 is performed in step S55 or S56, respectively.
Detailed description of 3 will be omitted.

According to the sixth method, the integrated capacity can be obtained with higher accuracy, and it is possible to cope with a sudden increase in the current capacity.

Next, for example, in the case of the first method, as shown in FIG.
_max (<6 Cph), and then decreases. In this case, although the current capacity exceeds 5 Cph and reaches _Cmax , the capacity of _Cmax−5 Cph is charged. Nevertheless, since _Cmax is not more than the reference level (5 Cph) + the step width Cph at that time,
The capacity (such a capacity is hereinafter referred to as a capacity to be integrated as appropriate) is not included in the integrated capacity.

Therefore, according to the first method, an integrated capacity smaller than the true integrated capacity by the capacity to be integrated is calculated. This is the same for the second to sixth methods.

The flowchart of FIG. 14 shows the processing of the microcomputer 1 when the integrated capacity is calculated by the seventh method in which the capacity to be integrated is also the object of integration. , The reference level at that time (FIG. 15
(A)) and the time change of the integrated capacity (FIG. 15 (B)).

In the case of the seventh method, it is detected whether or not the current capacity has increased or decreased by more than the step width Cph, and the current capacity before the increase or decrease by the step width Cph is determined as the minimum capacity or the minimum capacity, respectively. As the maximum value of the capacitance, the difference between the maximum value of the capacitance and the minimum value of the capacitance is
It is configured to integrate the integrated capacity.

That is, when the current capacity decreases by the step width Cph or more and then increases by the step width Cph or more, the minimum value (minimum value) of the current capacity in the section is detected.
This is defined as the minimum capacity value. When the current capacity increases by the step width Cph or more and thereafter decreases by the step width Cph or more, the maximum value (maximum value) of the current capacity in that section is detected, and the detected value is set as the maximum value of the capacity. The minimum value of the capacitance and the maximum value of the capacitance always appear alternately. According to the seventh method, for example, when the maximum value of the capacitance is detected, the minimum value of the capacitance detected immediately before is detected from the maximum value of the capacitance. The accumulated capacity is updated by adding the subtracted value to the accumulated capacity.

More specifically, first, at step S61
In step, the current capacity is detected, and the process proceeds to step S62, where the current capacity is stored in variables RAML and RAMH.
Set as the initial value.

Here, the variables RAML and RAMH are stored in a register constituting the register section 5 (FIG. 1), and each is used to detect the minimum value or the maximum value of the capacitance. .

Thereafter, the flow advances to step S63, where the current capacity is detected again. Then, in step S64, with the difference D ₁ of the current capacity and variable RAML (= current capacity -RAML) is determined, the difference D ₂ (= RAMH- current capacity) of the variable RAMH and the current capacity is obtained, step proceeds to S65, the difference D ₁ is the step width Cp
It is determined whether it is greater than h. In step S65, if the difference D ₁ is determined to be greater than the step width Cph, namely, the current capacity is first detected current capacity (current capacity detected at step S61) (e.g., a user, a battery pack If the current capacity is increased by more than the step width Cph from the current capacity detected when the user purchased the 20 and started to use the current capacity, the current capacity detected first is regarded as the minimum capacity value. Then, the process proceeds to step S66, the variable RAMH is validated, and the process proceeds to step S69. Here, while the variable RAMH is valid, in a subsequent process, the variable RAMH is set as an object to be updated,
The variable RAML is not updated.

On the other hand, in step S65, the difference D
_{If 1} is not greater than the step width Cph, the process proceeds to step S67, the difference D ₂ is the step width Cp
It is determined whether it is greater than h. In step S67, the case where the difference D ₂ is not greater than the step width Cph, namely the current capacity than the first detected current capacity, to not be increased by more than the step width Cph, also not be reduced In this case, the process returns to step S63.

In step S67, the difference D ₂
Is larger than the step width Cph, that is, when the current capacity is reduced by the step width Cph or more from the first capacity detected, the current capacity detected first is regarded as the capacity maximum value. Then, step S6
Proceeding to step S8, the variable RAML is made valid, and step S69
Proceed to. Here, while the variable RAML is valid, in a subsequent process, the variable RAML is set as an update target, and the variable RAMH is not set as an update target.

As described above, the variable RAMH or R
If one of the AMLs is valid, the current capacity is detected again in step S69, and the process proceeds to step S70, where it is determined which of the variables RAMH and RAML is valid. Is done. If it is determined in step S70 that the variable RAMH is valid, that is, if the previous extreme value of the current capacity is the minimum value (minimum capacity value), the process proceeds to step S71, and the current capacity is set to the variable RAMH. It is determined whether it is greater than.

If it is determined in step S71 that the current capacity is larger than the variable RAMH, step S72
The variable RAMH is updated to the current capacity, the process returns to step S69, and the process from step S69 is repeated.
That is, in this case, since the variable RAMH remains valid, the processing of steps S69 to S72 is repeated, whereby the variable RAMH stores the current capacity from the previous detection of the minimum value of the capacity to the present. The maximum value is stored.

If it is determined in step S71 that the current capacity is not larger than the variable RAMH, that is, the current capacity detected is the maximum of the current capacity since the previous minimum value of the capacity was detected. If the value is less value, the process proceeds to step S73, is determined difference D ₂ between the variables RAMH and the current capacity, the process proceeds to step S74. At step S74, the difference D ₂ is whether a larger step width Cph is determined.

If it is determined in step S74 that the difference D ₂ is not larger than the step width Cph,
Although the current capacity has decreased, the extent of the decrease is due to the step width Cp.
If not more than h, the process returns to step S69. Further, in step S74, the case where the difference D ₂ is determined to be greater than the step width Cph, namely, the current capacity, the variable RA
When MH (the maximum value of the current capacity from the detection of the previous minimum value of the capacity to the present) decreases by the step width Cph or more, the variable RAMH at that time is determined as the maximum value of the capacity. Then, the process proceeds to step S75, where the integrated capacity is
The value is updated to the value obtained by adding the difference between the variables RAMH and RAML, and the process proceeds to step S76.

In step S76, the variable RAML is validated in place of the variable RAMH. That is, after the maximum value of the capacity is detected, the variable RAML is validated.
Proceeding to 77, the variable RAML is updated to the current capacity, the process returns to step S69, and the processing from step S69 is repeated.

In this case, in step S70, the variable RA
It is determined that the ML is valid. If it is determined in step S70 that the variable RAML is valid, the process proceeds to step S78, and it is determined whether the current capacity is smaller than the variable RAML.

If it is determined in step S78 that the current capacity is smaller than the variable RAML, the process proceeds to step S79.
The variable RAML is updated to the current capacity, the process returns to step S69, and the processing from step S69 is repeated.
That is, in this case, since the variable RAML remains valid, steps S69, S70, S78, and S7 are performed.
The process of No. 9 is repeated, whereby the minimum value of the current capacity from the detection of the previous maximum value of the capacity to the present is stored in the variable RAML.

If it is determined in step S78 that the current capacity is not smaller than the variable RAML, that is, the current capacity that has just been detected is the minimum of the current capacity since the previous maximum value of the capacity was detected. If the value is equal to or greater than the value, the process proceeds to step S80, where the current capacity and the variable RAM
The difference D ₁ and L is required, the process proceeds to step S81. At step S81, the difference D ₁ whether larger step width Cph is determined.

[0092] In step S81, if the difference D ₁ is not greater than the step width Cph, namely,
Although the current capacity has increased, the increase is due to the step width Cp.
If not more than h, the process returns to step S69. Further, in step S81, if the difference D ₁ is determined to be greater than the step width Cph, namely, the current capacity, the variable RA
When the value increases by the step width Cph or more from ML (the minimum value of the current capacity from the detection of the previous maximum value of the capacity to the present), the variable RAML at that time is determined as the minimum value of the capacity. Then, in step S82, the variable RAM
Instead of L, the variable RAMH is made valid, that is, after the minimum value of the capacity is detected, the variable RAMH is made valid, the process proceeds to step S83, the variable RAMH is updated to the current capacity, and the process returns to step S69. The processing from step S69 is repeated.

FIG. 15 shows a temporal change of the reference level (FIG. 15A) and the integrated capacity (FIG. 15B) when the integrated capacity is calculated as described above.

In the embodiment shown in FIG. 15, first, the current capacity (FIG. 15 (A)) is increased, and thus charging is being performed. In this case, at time t1 when the current capacity has increased by more than the step width Cph from the initial current capacity,
The initial current capacity is set to the minimum capacity value, and the variable RAMH is made valid.

While the variable RAMH is valid, the variable RAMH is updated to the maximum value of the current capacity from time t1 up to now. And charging is finished,
When the discharge is started, the current capacity (FIG. 15A) decreases. When the current capacity decreases to a value smaller than the variable RAMH by the step width Cph or more, the current capacity is stored in the variable RAMH at time t3. The value (current capacity) is determined as the capacity maximum value. That is, for example, FIG.
In the case shown in (A), the maximum value appears at time t2, and this maximum value is determined as the capacitance maximum value at time t3.

When the maximum value of the capacity is determined, the integrated capacity (FIG. 15B) is increased by the difference between the variables RAMH and RAML, the variable RAML is validated, and The capacity (current capacity detected at time t3) is set.

Thereafter, as long as the variable RAML is valid, the variable RAML is updated to the minimum value of the current capacity from time t3 (time when the variable RAML is valid). Then, when the discharging is completed and the charging is started again, the current capacity (FIG. 15A) increases, but this current capacity is determined by the step width Cp from the variable RAML.
When the value increases by h or more, the value (current capacity) stored in the variable RAML at the time t4 is determined as the minimum capacity value.

When the minimum value of the capacity is determined, the variable RAMH is made valid again, and the current capacity (current capacity detected at time t4) is set in the variable RAMH. Then, the variable RAMH is updated, and thereafter, the integrated capacity is similarly obtained.

As described above, the current capacity is equal to the step width C.
ph is detected or not, and the current capacity before the increase or decrease is greater than or equal to the step width Cph is defined as the minimum value or the maximum value of the capacitance, respectively, and the difference between the maximum value and the minimum value of the capacitance is calculated. Since the integrated capacity is added to the integrated capacity, an increase in the current capacity below Cph, which can be regarded as an error, is ignored, and as a result, the integrated capacity is
It can be obtained relatively accurately. Further, according to the seventh method, the capacity to be integrated is also included in the integrated capacity, so that the integrated capacity can be obtained with higher accuracy.

The above-described first to fourth methods in which the reference level takes only a predetermined fixed value approach the seventh method by reducing the interval between the fixed values.

Next, the integrated capacity obtained by the above method is displayed on the display unit 6 and the like as described above. In the case of the seventh method, the maximum value of the capacity is determined. Until, the charge capacity from the previous minimum capacity value is not added to the integrated capacity, so the change in the integrated capacity during that time will not be reflected on the display (only when the maximum capacity value appears, the integrated capacity display It does not change). That is, if the integrated capacity value obtained by the seventh method is displayed as it is, the display value of the display unit 6 (hereinafter, appropriately referred to as the display capacity value) does not change in real time.

Therefore, in order to change the display capacity value in real time, the microcomputer 1 may be made to perform a display process according to, for example, a flowchart shown in FIG. That is, in this case, first, step S91
In, it is determined which of the variables RAML or RAMH is valid. If it is determined in step S91 that the variable RAMH is valid, the process proceeds to step S92, where the variable RAMH and the RAM are added to the integrated capacity.
The difference from L is added, the added value is displayed as the display capacity value, and the display processing ends.

In step S91, the variable RA
If it is determined that the ML is valid, the process proceeds to step S93, where the integrated capacity is displayed as it is as the display capacity value, and the display processing ends.

In this case, as shown in FIG. 17, the period from the previous minimum value of the capacitance to the appearance of the next maximum value of the capacitance is
Increment of capacity from its minimum value (RAMH-RAM
L) is added to the integrated capacity (the portion indicated by the dotted line in the figure) and displayed, so that the display capacity value can be changed in real time.

The case where the present invention is applied to a personal computer system has been described above, but the present invention is also applicable to a battery pack used in electronic equipment other than a personal computer.

In the case of FIG. 14, when the maximum value of the capacity is determined, the difference from the previous minimum value of the capacity is added to the integrated capacity, and the variable RAML is updated to the current capacity. , And others, for example, if the current capacity is
When the value of the variable RAML is increased to a value equal to or larger than the step width Cph, the difference between the variable RAMH and RAML is added to the accumulated capacity, and the variable RAML is updated to the value stored in the variable RAMH, thereby increasing the accumulated capacity. You can ask for it. In this case, it is possible to obtain an integrated capacity that changes in real time.

In the present embodiment, the current capacity is detected from the battery voltage. However, the current capacity may be detected by, for example, a current integration method or the like.

Further, the secondary battery E is not limited to a lithium ion battery, and for example, a Nicd battery or the like can be used as the secondary battery E.

In the case of the seventh method among the first to seventh methods described above, the integrated capacity is obtained without using the reference level. Also, it is possible to calculate the integrated capacity using the reference level. In this case, the reference level is changed in the same manner as any one of the first to sixth methods, and the variables RAMH and RAML store the difference value of the value that should be stored therein from the reference level. Let it do. In this case, the variable RAM
It is possible to reduce the number of bits of a register necessary for storing H and RAML.

Furthermore, the integrated capacity is determined by the battery pack 20
Is calculated until it becomes unusable, and therefore may have an enormous value. Therefore, the number of significant digits for the display or the like must be appropriately determined.

In this embodiment, the remaining capacity detected from the battery voltage is used as it is as the current capacity. Alternatively, for example, the moving average value of the remaining capacity in a predetermined period is provided to the microcomputer 1. It is possible to calculate and use this as the current capacity.

Here, the moving average value of the remaining capacity in a predetermined period can be calculated as follows.
That is, when considering that the time window corresponding to the predetermined period moves in the traveling direction of the time, when the remaining capacity at the current time is taken into the time window, the remaining capacity already taken in is calculated from the sum of the remaining capacity already taken. , The value obtained by subtracting the average value (the sum of the remaining capacity already in the time window divided by the width of the time window) and the remaining capacity at the current time is divided by the width of the time window The value obtained is the moving average value. Therefore, the current moving average value can be calculated simply by storing the sum of the remaining capacities used to calculate the previous moving average value, without having to store each remaining capacity within the time window. can do. That is, the current moving average value is a value obtained by dividing the value by the width of the time window from the total value of the remaining capacity used to calculate the previous moving average value (this is the previous moving average value). ) Is subtracted, the remaining capacity at the current time is added to the subtracted value, and the result is divided by the width of the time window.

This moving average value is equivalent to a value obtained by passing the remaining capacity through a low-pass filter (RC filter) composed of a resistor and a capacitor at a time constant corresponding to the width of the time window. .

Further, in this embodiment, the case where the integrated value of the charge capacity is obtained has been described. However, the present invention is also applicable to the case where the integrated value of the discharge capacity is obtained. That is,
The current capacity is not the current remaining capacity of the secondary battery, but the free capacity of the current secondary battery (the used capacity when the full charge is set to 0, for example). 3 (A) is equivalent to changing the sign of the value of the vertical axis of the time change of the current capacity from positive to negative), and calculating the integrated value of the discharge capacity in the same manner as described above. Can be.

In the present invention, "greater than"
It is not necessary to distinguish strictly from the case of “or more” in the present specification and the drawings. The same applies to the case of “smaller” (or “less than”) and the case of “less than”.

[0116]

According to the capacity integration method of the first aspect and the battery pack of the ninth aspect, the current capacity of the secondary battery is detected, and the current capacity has changed by a predetermined step width or more. , The integrated capacity is updated to the value obtained by adding a change of the current capacity by a predetermined step width or more. Therefore, it is possible to obtain a relatively accurate integrated value of the capacity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a personal computer system to which the present invention is applied.

FIG. 2 is a flowchart illustrating a first capacity calculation method.

FIG. 3 is a diagram for explaining a first capacity calculation method.

FIG. 4 is a flowchart for explaining a second capacity calculation method.

FIG. 5 is a diagram for explaining a second capacity calculation method.

FIG. 6 is a flowchart for explaining a third capacity calculation method.

FIG. 7 is a diagram for explaining a third capacity calculation method.

FIG. 8 is a flowchart illustrating a fourth capacity calculation method.

FIG. 9 is a diagram for explaining a fourth capacity calculation method.

FIG. 10 is a flowchart for explaining a fifth capacity calculation method.

FIG. 11 is a diagram for explaining a fifth capacity calculation method.

FIG. 12 is a flowchart for explaining a sixth capacity calculation method.

FIG. 13 is a diagram for explaining a sixth capacity calculation method.

FIG. 14 is a flowchart illustrating a seventh capacity calculation method.

FIG. 15 is a diagram illustrating a seventh capacity calculation method.

FIG. 16 is a flowchart illustrating a process when displaying the integrated capacity calculated according to the flowchart of FIG. 14;

FIG. 17 is a diagram showing a time change of a display capacitance value.

[Explanation of symbols]

1 microcomputer (detection means) (judgment means) (update means)
2 switch, 3 current detection circuit, 4 voltage detection circuit, 5 register section, 6 display section (display means),
20 Battery pack

Claims (10)

[Claims] 1. A capacity integration method for calculating an integrated capacity which is an integrated value of a charge capacity or a discharge capacity of a secondary battery, wherein a current capacity of the secondary battery is detected, and the current capacity is equal to or larger than a predetermined step width. If the capacity has changed, the integrated capacity is updated to a value obtained by adding a change of the current capacity by a predetermined step width or more to the value of the integrated capacity. 2. The method according to claim 1, wherein the current capacity is compared with a predetermined reference level, and when the current capacity is larger than the predetermined reference level by the predetermined step width or more, the predetermined reference level or the integrated capacity is calculated. 2. The capacity integrating method according to claim 1, wherein the value is updated to a value obtained by adding the value of the predetermined step width unit to a value. 3. When the current capacity is smaller than the predetermined reference level, the predetermined reference level is updated to a value obtained by subtracting the value of the predetermined step width unit from the value. The capacity integration method according to claim 2. 4. When the current capacity is smaller than a predetermined reference level by a predetermined step width or more, the predetermined reference level is updated to a value obtained by subtracting the value of the predetermined step width unit from the value. 3. The capacity integrating method according to claim 2, wherein: 5. The capacity integrating method according to claim 2, wherein when the current capacity is smaller than the predetermined reference level, the predetermined reference level is updated to the current capacity. 6. When the current capacity increases by the predetermined step width or more, when the current capacity decreases by the predetermined step width or more, the minimum value of the current capacity before the increase is reduced. The capacity according to claim 1, wherein a subtraction value obtained by subtracting the capacity maximum value that is the current capacity before the decrease is obtained, and the integrated capacity is updated to a value obtained by adding the subtraction value to the value. Multiplication method. 7. The capacity integration method according to claim 1, wherein the moving average value is used as the current capacity. 8. The method according to claim 1, wherein the current capacity is a current remaining capacity or a free capacity of the secondary battery. 9. A battery pack having a built-in secondary battery and obtaining an integrated capacity that is an integrated value of its charge capacity or discharge capacity, a detecting means for detecting a current capacity of the secondary battery; Determining means for determining whether or not has changed by a predetermined step width or more, and when the current capacity has changed by a predetermined step width or more, the integrated capacity is set to the value and the predetermined step width of the current capacity is changed A battery pack comprising: updating means for updating to a value obtained by adding the above change. 10. The battery pack according to claim 9, further comprising display means for displaying the integrated capacity.