JP2002181906A - Method and equipment for calculating residual capacity of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that an accurate residual capacity calculation means can be constructed relatively easily because the quantity of a current going in and out with respect to a battery is counted in a battery residual capacity calculation method by a current integrating method, but there is a limit in the detection of the current going in and out with respect to the battery and a minute current can not be counted and, since self-discharge or the like is not the current going in and out with respect to the battery, the current can not be counted and errors are also integrated in this current integration method and the calculation result of the residual capacity of the battery is entirelty different from a practical calculation result. SOLUTION: When the quantity of the current going in and out with respect to the battery is large enough to count, the residual capacity of the battery is calculated by the current integrating method. However, if a flowing current becomes little and a current becomes the minimum value or less, a means changing over the current integrating method to a voltage method is operated on the basis of the judgment of a current minimum value judging means to calculate the residual capacity of the battery by the voltage method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calculating the remaining capacity of a battery, a recording medium storing the method, and a device system incorporating the recording medium.

[0002]

2. Description of the Related Art As a conventional method for obtaining the remaining time or remaining capacity of a battery, a time integration method, a current integration method and a voltage method have been proposed and actually incorporated in equipment. The time integration method is often used when the load is relatively constant and the remaining battery capacity can be determined only by the usage time, such as in an electric shaver. The current integration method is used in portable video cameras and the like where the load fluctuates during use, monitors the amount of current used, subtracts from the initial remaining capacity value during discharging, and adds during charging to take out from the battery. Calculate the amount of current.
In the voltage method, battery characteristic data is obtained in advance and stored in a recording medium such as a ROM in the form of a table of battery voltage versus remaining battery capacity. At the time of operation, the battery voltage is detected and converted to the remaining capacity by referring to the stored table. It is often used in devices where it is relatively difficult to accurately detect and integrate a discharge current, such as a mobile phone that performs pulse discharge, and when cost is a priority. There is also a method of combining the current integration method and the voltage method. When the remaining battery capacity is low, the voltage drop curve becomes clear, so that the voltage can be easily detected, and the remaining capacity calculation accuracy is better than the current integration method of the voltage method. Therefore, the voltage method is used when the remaining capacity is almost empty, and the current integration method is used in other regions. In addition, a voltage method is used at the time of charging, and a current integration may be used at the time of discharging. When charging, the charging current is constant,
This is because it is not necessary to consider the effect of the current change on the battery voltage, and it is relatively easy to convert the battery voltage to the remaining capacity during charging. In any of the remaining battery capacity calculation methods, it is necessary to obtain an initial value of the remaining capacity. In the conventional voltage method, data of voltage versus remaining capacity at a current value that normally flows is collected and stored in a table, and is read from the stored table data when necessary. In the current integration method, the initial value is set to 100% when the battery is fully charged, or the initial value is set to zero when the battery is partitioned to the final voltage. Alternatively, when the battery remaining capacity is started halfway, the battery remaining capacity value at the last use is counted as the initial value.

[0003]

In the conventional time integration method, when the load changes, the time during which the battery can be used changes, so that it is unusable for a device having a variable load. Also, in the voltage method, it takes a long time until a stable battery voltage is obtained if the fluctuation of the load is large. Therefore, it is difficult to obtain an accurate battery voltage value. Even if a battery voltage value having a large error is converted into a battery remaining capacity value, there is a problem that the calculated battery remaining capacity value becomes a value including a large error. Furthermore, since the data table for converting the battery voltage value to the remaining battery value differs depending on the size of the load, a large amount of data is acquired to improve the accuracy, and many data tables are stored in the RO.
It is necessary to save the data in M, which takes a lot of man-hours and increases the cost. On the other hand, the current integration method counts the amount of current flowing into and out of the battery, so that a highly accurate remaining capacity calculating means can be constructed relatively easily. However, there is a limit to the detection of the current flowing into and out of the battery, and a minute current cannot be counted, and self-discharge and the like cannot be counted because it is not a current flowing into and out of the battery. The end result may be quite different. In addition, in the case of combining the conventional voltage method and the current integration method, even if the remaining capacity calculated by the current integration method is incorrect, the remaining voltage is calculated by the voltage method at the end of discharging, so that it becomes consistent at the end. However, the problem of the above-described current integration method remains as it is while the calculation is performed by the current integration method on the way. In particular, in the current integration method, the initial value becomes important in determining the accuracy of the remaining battery capacity calculation. However, in the conventional method, the initial value of the battery discharged until it is fully charged or empty is not a problem, but when the battery is charged or discharged halfway, the remaining battery capacity is self-discharged, etc. from the stored previous battery remaining capacity value. is decreasing. Although a method of predicting and reducing the amount of self-discharge is also used, in reality, individual batteries have individual differences and greatly differ depending on differences in use environment. In particular, when not used for a long time, there is a problem that an initial value far from the actual value is given. Therefore, solving the above problems has become a major issue.

[0004]

The invention according to claim 1 is based on a current integrating method for calculating a remaining battery value by counting the amount of flowing current. However, when the current minimum value is determined to be the minimum value, the voltage method is switched to a method of converting the battery voltage value to the remaining battery value. That is, when the current is small, the error increases in the current integration method, and conversely, there is a feature that the problem is solved by switching to the voltage method in which the error decreases.

According to a second aspect of the present invention, when the current flowing for a relatively long predetermined time is equal to or less than a predetermined current value,
The battery voltage fluctuation is within a predetermined voltage fluctuation range, and the battery voltage value to be detected is regarded as an open battery voltage value, and the current minimum value determining means determines that the battery voltage value is equal to or less than the current minimum value.

[0006] In the invention according to claim 3, the charger,
Alternatively, immediately after the power supply of the set is started, first, a function value of a value obtained by multiplying the battery impedance by the current value is obtained.
The open battery voltage value is calculated by adding or subtracting this function value to or from the detected battery voltage. In other words, there is a feature that the open battery voltage value is calculated and calculated by compensating the detected battery voltage value for a voltage drop or an increase due to the battery impedance. This is an effective means for determining the initial value of the remaining capacity in the first aspect of the present invention.

According to the invention, the open battery voltage value is measured before the charging or discharging current flows, and when the charger or the set is turned on, the measured open battery voltage value is measured. There is a feature to convert to capacity. This method is also effective means for determining the initial value of the remaining battery capacity in the first aspect of the invention, as in the third aspect.

According to a fifth aspect of the present invention, a predetermined time before charging or discharging is started,
It has means for checking whether a current equal to or more than a predetermined current has flown. If there is a record of the flow, there is a feature that the last stored battery remaining capacity is called and the value is used as an initial value of the remaining capacity. The battery voltage immediately after charging or discharging at which a certain amount of current flows has a large voltage fluctuation even when the current is stopped. Therefore, if there is a record in which a current equal to or more than a predetermined current has flowed during a predetermined time before the time when the open battery voltage is measured, the current integration method from the previous time can be used without obtaining the initial value of the remaining battery capacity by the voltage method. It is a continuing feature.

Further, in the invention of claim 6, there is provided a means for recording the battery detached from the set between the time when the previous charge / discharge was stopped and the present time. When there is a detachment record, the present open battery voltage value is converted into a remaining battery capacity value and set to an initial value. The purpose is to prevent the use of the previous remaining battery capacity value as an initial value even though the battery has been replaced with another battery.

Further, the invention of claim 7 is characterized in that the remaining capacity calculation method of the invention of claims 1 to 6 is stored in a recording medium such as a hard disk or a semiconductor memory.

The invention according to claim 8 is characterized in that the recording medium according to claim 7 is incorporated in a system of an apparatus using a battery as a power supply.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 according to claim 1 will be described with reference to FIG. FIG. 1 is a flowchart common to charge and discharge. First, charge / discharge is started in step 1 and step 2
Detects the current value Im. Next, in step 3, the current is integrated and the current integration amount Q is counted. If it is determined in step 4 that the current is the minimum value, the process proceeds to step 5, and if it is determined that the current is equal to or more than the minimum value, the process proceeds to step 9. In step 5, the battery voltage value VB is detected, and converted to the remaining battery capacity C with reference to the battery voltage value versus remaining battery capacity table 13 stored in the ROM or the like in step 6. In step 7, the previous battery capacity value Cr stored in the memory or the like is replaced with the remaining battery capacity value C obtained in step 6, and updated. Next, the current integration amount Q that has been integrated so far is reset to zero, the process returns to step 2, and the current is newly integrated. On the other hand, in step 9, the previous battery capacity value Cr stored in the memory or the like is called. Next, in step 10, the integrated current amount Q is subtracted from the previous remaining battery capacity value Cr to obtain a new remaining battery capacity value C. Next, at step 11, the full charge capacity value Cf stored in the ROM or the like is called. And step
At 12, the remaining battery capacity is calculated as a percentage by dividing C in step 10 by Cf and multiplying by 100. However, the current value detection in step 2, the current integration in step 3, and the determination of the minimum current value in step 4 are repeated while the process proceeds to any one of the flow from step 5 to step 8 and the flow from step 9 to step 12. are doing. Therefore, in the flow that proceeds to step 5 in FIG. 1, the battery remaining capacity value C in step 6 obtained by first executing the flow becomes the initial value of the battery remaining capacity, as performed by the conventional voltage method. Alternatively, in the flow that proceeds to step 9, the remaining battery capacity value Cr before step 9 becomes the initial value of the remaining battery capacity as performed by the conventional current integration method. In FIG. 1, charging and discharging are represented by a common flow, so that the current value Im and the current integrated amount Q are set to positive values during discharging, and vice versa during charging. By the way, in the flowchart of FIG. 1, for example, the detection of the battery voltage value VB in step 5 is brought before or after step 2, and a change that naturally gives an equivalent result does not depart from the gist of the present invention.

Next, a second embodiment according to claim 2 will be described with reference to FIG.
Indicated by This is a novel invention of the content of the minimum current value determination in step 4. That is, if the detected current Im is equal to or less than the predetermined current value for the predetermined time, it is determined that the current is the minimum value. Therefore, in this case, as shown in FIG. 2, the detection of the battery voltage VB in step 5 is brought before the determination of the minimum current value in step 4. By the way, a predetermined time is required even for a minimum time to detect whether the current or the voltage is detected. However, the predetermined time mentioned here means that a means for consciously setting a relatively long time, for example, a time of 1 minute or more, with a timer or the like is taken. Then, the battery voltage can be detected only when the battery voltage does not fluctuate, which can be regarded as an open battery voltage, and can be converted into an accurate remaining battery capacity.

Next, a third embodiment is shown in FIG. In the first and second embodiments shown in FIGS. 1 and 2, when the determination of the minimum current value is YES in step 4 and the process proceeds to step 5, charging and discharging are performed immediately before the start of charging and discharging in step 1. However, since the battery voltage continues to fluctuate, an error occurs in the detected battery voltage. Therefore, between step 1 and step 4 in FIG. 1, a step of calculating the voltage fluctuation ΔVB due to the battery impedance R0, correcting the detection voltage value VB, and calculating the open battery voltage value V0 is inserted. In the calculation for obtaining ΔVB, it is preferable to multiply the product of the battery impedance R0 and the current value Im by a constant such as the degree of deterioration as a coefficient. Then, the open battery voltage value becomes Δ at the time of discharging to the detected battery voltage value VB.
It is obtained by adding VB and subtracting ΔVB when charging. Next, in step 17, the open battery voltage value V0 obtained from the calculation is converted into the current battery remaining capacity value C by referring to the table 13 in FIG. Also, in the first flow in which charging / discharging is started in Step 1, if the determination in Step 4 is NO and the process proceeds to Step 9, the remaining battery value Cr before Step 9 becomes the initial value obtained in Step 17.

Next, a fourth embodiment is shown in FIG. As in the third embodiment, a step for determining an initial value of the remaining battery capacity is inserted. That is, it has a pre-processing step before charging / discharging starts. Step 18 is a step in which a switch for charging or discharging is turned on. For charging, there is generally no charge switch, and this shows a state where the set is connected to a charger connected to the commercial AC power supply for home use. Next, in step 19, the battery voltage value VB is detected, and VB is stored in the table 13 in FIG.
Is converted to the current battery remaining capacity value C. However, the detection of the battery voltage value VB in step 19 may be performed before the charging or discharging switch is turned on. Even when the switch for charging or discharging is off, the battery voltage VB can be detected continuously at a very low battery power and always behind the operation of the set. Then, in step 1, a charge / discharge current is supplied for the first time. Therefore, in this case, the battery voltage value VB is obtained as an open battery voltage value by actual measurement by providing a time during which no current is forced to flow before charging / discharging, or by constantly monitoring the battery voltage with a minimum current. I do.

Next, a fifth embodiment is shown in FIG. First, in step 18, a switch for charging or discharging is turned on. Next, at step 21, it is checked whether a current equal to or more than a predetermined current has flowed a predetermined time before, for example, one minute before the present time. If a predetermined current or more flows, it means that the battery was in a charged or discharged state at that time. The proof that the current has flowed is recorded in the memory, and even if the charge or discharge switch is turned off, the timer can be operated with a very small current, and whether or not a current of a predetermined current value or more flows during a predetermined time period Can be easily checked. If there is no record of the flow of the current, step 21 is YES, and since there is little change in the battery voltage value VB, the process proceeds to step 19, where the battery voltage value VB is detected. Therefore, in step 20, the battery voltage value VB is regarded as the open battery voltage value, and converted to the current battery remaining capacity value C with reference to the table 13 of FIG. Then, in step 22, the previous battery remaining capacity value Cr is updated with the current battery remaining capacity value C obtained in step 20. If the determination in step 21 is NO, the process proceeds to step 23, and the stored remaining battery capacity value Cr is called. That is, if there is a record in which a current equal to or greater than a predetermined current has flowed between a predetermined time and the present, it can be said that not much time has elapsed since the previous charging or discharging, and thus the remaining battery capacity before the last time was stored. Even if the value is used as it is, it can be determined that almost no error occurs.
Therefore, in step 24, the remaining battery capacity value C is determined to be the previous battery remaining capacity value Cr, and in step 22, the previous battery remaining capacity value is determined.
Update Cr with C. The previous battery remaining capacity value Cr updated in step 22 is used as an initial value of the battery remaining capacity in the subsequent battery remaining capacity calculation flow.

Next, a sixth embodiment is shown in FIG. This is an example in which Step 21 of Embodiment 5 is replaced with Step 25. In step 25, it is determined whether or not there is a record in which the battery has been detached from the current time after the previous charging / discharging was stopped. The fact that there is a record of attaching and detaching the battery means that the battery has been replaced with another battery or that sufficient time has elapsed since charging / discharging was stopped and the battery voltage is stable. Similarly, it has been a while since this other battery has been charged or discharged, and it can be considered that the battery voltage is stable. Therefore, if there is a detached record, the process proceeds to step 19. If there is no detached record, it is the same as the battery used last time, so it is assumed that the previous battery remaining capacity value is equal to the current battery remaining capacity value, and the process proceeds to step 23 to call the previous battery remaining capacity value Cr. . The subsequent flow is the same as in the fifth embodiment. Of course, the result is the same with only the record with the battery on or the record with the battery removed.

Next, a seventh embodiment is shown in FIG. This is an embodiment in which the fifth embodiment and the sixth embodiment are combined. In the sixth embodiment, in step 25, if there is no record of removing the battery from the last stop of charge / discharge to the present, the process proceeds to step 23. Thus, in the seventh embodiment, before proceeding to step 23, no current detection of a predetermined current or more is inserted from a predetermined time before step 21 of the fifth embodiment to the present. However, FIG.
In this example, the logic is reversed and the current is detected to be equal to or greater than a predetermined current from a predetermined time before to the present, but the purpose is the same. The subsequent flow is described in the fifth or sixth embodiment.
Is the same as That is, even if there is no record of removing the battery in step 25, if a current equal to or greater than a predetermined current has flowed from a predetermined time before to the present, charging or discharging has been performed within a predetermined time, and the fluctuation of the battery voltage is large. There is a possibility. Therefore, even if the battery voltage is detected, the error is large, so the previous value of the remaining battery capacity is used as the initial value of the remaining battery capacity. Since the previous charge / discharge was executed within the predetermined time, even if the previous remaining battery capacity value is used, almost no error occurs.

Embodiment 8 is a recording medium such as a semiconductor memory or a hard disk in which a program for the above-described remaining capacity calculation method is stored.

The ninth embodiment is a device system for calculating the remaining capacity of a storage medium storing the above-described method for calculating the remaining capacity in a device using a battery such as a mobile phone, a video camera, or a notebook personal computer.

[0021]

According to the first aspect of the invention, the current integration method for accurately calculating the remaining battery value when the flowing current is relatively large or has a large fluctuation is adopted, so that the calculation accuracy of the remaining capacity is improved. effective. When the current is small, the error in the current value to be detected is large, and the error in the integrated current value also accumulates. However, at this time, the accuracy of the remaining battery capacity is calculated by switching to a voltage method that improves the accuracy of the remaining battery capacity value. Has the effect of becoming better. The provision of the minimum current value judging means shown in step 4 has a great effect that the method can be surely switched to the method with the highest accuracy among the battery remaining capacity calculation methods of the current integration method and the voltage method.

According to the second aspect of the present invention, even if the current is equal to or less than the minimum value, when a large current change occurs immediately before the detection, the battery voltage becomes unstable, and the detected voltage deviates from the open battery voltage. Results in incorrect values. Therefore, if the flowing current is less than the minimum value for a relatively long predetermined time,
The fluctuation of the battery voltage becomes small, and the minimum current value determination means determines that the current value is equal to or less than the minimum current value. Since this battery voltage can be regarded as substantially an open battery voltage, there is an effect that it can be converted into an accurate current battery remaining capacity value.

According to a third aspect of the present invention, there is provided a battery charger,
Alternatively, immediately after the power supply of the set is started, first, a function value of a value obtained by multiplying the battery impedance by the current value, that is, a voltage variation due to the battery impedance is obtained. The open battery voltage value is calculated by adding or subtracting this voltage variation to or from the detected battery voltage. Then, the open battery voltage value obtained by this calculation is converted into a battery capacity value, and an initial value of the remaining battery capacity in the remaining capacity calculation method according to claims 1 and 2 is obtained. Then, even if the battery is replaced, there is an effect that it can be guaranteed that the initial value is the initial value of the battery to be used from now on.

According to the fourth aspect of the present invention, immediately after the power of the charger or the set is turned on, and before the charging or discharging current flows, a time period during which no current flows is provided to accurately measure the open battery voltage value. There is an effect that the accuracy is improved as compared with the method of calculating the initial battery capacity value in claim 3.

However, for example, immediately after charging with the charger, the discharge switch of the set is turned on, and in a state where no current flows, the battery voltage is higher than the open battery voltage value because the battery voltage is higher by the charging impedance. Will be detected. If the higher battery voltage value is converted to the remaining battery capacity, the battery remaining capacity value becomes considerably larger than the actual remaining battery capacity, and the accuracy of calculating the remaining battery capacity deteriorates. Therefore, in claim 5, it is determined in step 21 whether a current equal to or greater than a predetermined current has been detected from a predetermined time before to the present. When there is a charged state, the remaining battery value before storage can be set to the initial value without actually measuring the open battery voltage value. This has the effect of preventing the occurrence of a remaining battery charge calculation error in the use of the set immediately after charging, which can occur particularly in mobile phones and the like. Of course, even when switching to charging during discharging or when discharging again immediately after turning off the discharge switch, the same error is caused, and the effect of preventing deterioration of accuracy is great.

However, the battery may be replaced by another battery. At this time, if the previous battery remaining capacity value is used as the initial value, there is a possibility that a completely wrong battery remaining capacity will be used as the initial value. Therefore, in step 25, it is determined whether or not the battery has been removed from a predetermined time before the present. If there is a detached record, there is a possibility that another battery has been replaced, and it can be considered that the battery has been charged / discharged and a certain time has elapsed. Also, even with the previous battery,
At least not immediately after charging and discharging. Therefore, even when the open battery voltage value is measured and converted to the remaining battery capacity value, an effect that almost no error occurs is obtained.

It is apparent that the seventh embodiment provides a more reliable effect by combining the effects of the fifth embodiment and the sixth embodiment.

The remaining capacity calculation method according to the first to sixth aspects of the present invention is stored in a recording medium such as a hard disk or a semiconductor memory according to the seventh aspect, so that the method is incorporated in a battery-driven apparatus system according to the eighth aspect. The accuracy of the remaining capacity display can be improved. Then, the effect that the device can be used more conveniently becomes extremely large.

[Brief description of the drawings]

FIG. 1 is a flowchart of a remaining capacity calculation method according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a remaining capacity calculation method according to a second embodiment of the present invention.

FIG. 3 is a flowchart of a remaining capacity calculation method according to a third embodiment of the present invention.

FIG. 4 is a flowchart of a remaining capacity calculation method according to a fourth embodiment of the present invention.

FIG. 5 is a flowchart of a remaining capacity calculation method according to a fifth embodiment of the present invention.

FIG. 6 is a flowchart of a remaining capacity calculation method according to a sixth embodiment of the present invention.

FIG. 7 is a flowchart of a remaining capacity calculation method according to a seventh embodiment of the present invention.

[Explanation of symbols]

 1 is step 1 12 is step 12 13 is data table 14 is step 14 25 is step 25

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2G016 CA04 CB06 CB12 CB22 CB32 CC01 CC03 CC06 CC10 CC12 CC14 CC21 CC23 CC28 5G003 CA05 CA11 EA05 FA07 5H030 AS20 BB21 FF42 FF44

Claims (8)

[Claims] A means for obtaining an initial value of a remaining battery capacity value;
In addition to having a current integration method of integrating the current flowing into and out of the battery to calculate the remaining battery capacity value, and having a current minimum value determination unit, when the current minimum value determination unit determines that the current minimum value or less, A battery remaining capacity calculation method comprising: means for switching to a voltage method for converting a battery voltage value to the battery remaining capacity value. 2. The battery remaining capacity calculating method according to claim 1, wherein said current minimum value judging means judges that said current minimum value is equal to or less than a current minimum value when a flowing current is equal to or less than a predetermined current value for a predetermined time. 3. An open battery voltage value calculated by adding or subtracting a function value of a value obtained by multiplying a battery impedance by a current value to or from a detected battery voltage value immediately after a charger or a set is turned on. The remaining battery capacity calculation method according to claim 1, wherein the remaining battery capacity value is converted into the initial value. 4. The method according to claim 1, wherein the open battery voltage value is detected before a charging or discharging current flows, and when the charger or the set is operated, it is converted to the remaining battery value and used as the initial value. Item 1. Battery remaining capacity calculation method according to item 1. 5. When a charger or a set is operated and a predetermined current or more flows from a predetermined time before to a present time,
2. The battery remaining capacity according to claim 1, further comprising current recording means for recording the flow, and if the current recording means has current recording, the last stored battery remaining value is called and used as the initial value. Calculation method. 6. A detachable recording means for recording when a battery or a battery is detached between a time when charging / discharging was stopped last time and a present time when a charger or a set is operated, and the detachable recording means has detachable recording. 2. The battery remaining capacity calculation method according to claim 1, wherein the open battery voltage is detected, converted to the remaining battery capacity value, and used as the initial value. 7. A recording medium storing the battery remaining capacity calculation method according to claim 1. 8. An apparatus system incorporating the recording medium according to claim 7.