JP2003157912A - Method and device for cell capacity detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make cell packs compatible with various specifications only by changing the data related to the cell packs, and efficiently estimate cell residual capacity in a short period of time even using a data processing means with an inferior operative function. SOLUTION: The data prepared for the detection of cell residual capacity are divided into the data related to unit cells and the data related to the combination of unit cells of the cell pack itself, and a necessary data related to a set of cells is constructed from both data so as to be calculated by an operation. Further, a temperature increase is estimated from a temporarily determined current value, and a variation of element value of a secondary cell and current variation are led out, and an operation of correcting the led-out current value by the preceding led-out current value, is repeatedly carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting a battery capacity in a secondary battery such as a lithium ion battery which can be charged and discharged a plurality of times.

[0002]

2. Description of the Related Art Conventionally, as a method of estimating the remaining capacity of a storage battery, the charging rate is measured from the voltage change when the current value flowing in the storage battery is below a predetermined value, and the full charging capacity is calculated from the charging rate and the integrated current value. It is shown that the remaining capacity can be estimated from the estimated full charge capacity and the charging rate (see Japanese Patent No. 3126591). However, since this estimation method corresponds to the full charge capacity measured when the battery current is very small, it is not suitable for estimating the remaining amount, and in particular, there is a problem such as a large error when a current is applied. large.

On the other hand, in order to improve the accuracy of estimation of the remaining usage time in the secondary battery, Japanese Patent Laid-Open No. 2-1
70372 “Lead storage battery residual capacity detection method” is available.
This has a plurality of data of discharge characteristics when temperature and discharge current change, and by referring to the data at appropriate times,
This is to maintain the accuracy of the remaining dischargeable time even if the temperature or current changes.

[0004]

However, in the case where the battery configuration is changed and used in various types such as a battery pack, the amount of data to be prepared becomes enormous and a minute amount is required. Even if there is only a difference in the battery pack, if the specifications are different, it is necessary to replace all the data, which leads to an increase in cost.

The present invention has been made in view of such inconvenience, and provides data provided for detecting the remaining battery level,
Separation into those relating to the unit cells and those relating to the battery pack itself relating to the combination of the unit cells,
An object of the present invention is to provide a battery capacity detection device that can correspond to battery packs of various specifications by simply replacing the data related to the battery packs by configuring the necessary data related to the assembled battery to be calculated from both data. And

Further, the temperature rise is estimated from the hypothetically determined current value, and the change in the element value of the secondary battery and the current change are derived from the temperature rise, and the derived current value is derived earlier. By repeating the operation of correcting the current value, even if using a data processing means with inferior operating capacity,
An object of the present invention is to provide a battery capacity detection device that can efficiently estimate discharge characteristics in a short time by using a small amount of reference data.

In the above description and the following description,
"Charging rate" means the secondary battery when the total capacity input to the secondary battery is "100" until the secondary battery is fully charged until it is fully charged. The percentage of the remaining capacity is expressed as "%".

The "open circuit voltage (hereinafter referred to as" OCV ")" is a terminal voltage measured by opening the both electrodes in a stable state by leaving the secondary battery for a long time. . Furthermore, the "open circuit voltage characteristic (hereinafter, referred to as" OCV characteristic ")" is the charging rate and OCV measured in advance for the secondary battery whose capacity is to be displayed.
Is held as information in a form that facilitates data processing such as a table, graph, or database.

Furthermore, the terminal voltage in a state where a charging / discharging load is applied to the secondary battery and a charging / discharging current is flowing will be simply referred to as "battery voltage". Also, the relationship between the charging / discharging time and the battery voltage during charging / discharging is "battery voltage characteristics", and the curve indicating the relationship between the discharging time and the battery voltage when discharging at a preset constant current during discharging is "discharging characteristics". Say.

[0010]

A method for detecting a battery capacity according to the present invention is shown in FIG. 2 which shows a relationship between a charging rate and an OCV in advance for a secondary battery 12 whose battery capacity is to be detected as illustrated in FIG. While measuring the OCV characteristics as described above and creating a database, the device values equivalently existing inside the secondary battery 12 as shown in FIG. 4 are created as a database, and the databased device values and the battery discharge conditions are used. From the discharge power or discharge current value of the battery and the charging rate estimated from the OCV.
The discharge characteristic of the secondary battery 12 is calculated using CV, and the remaining time or remaining capacity until the battery voltage reaches the final voltage Vt is estimated.

Then, when detecting the charging rate, the first OCV characteristic as shown in FIG. 21 (a) in which the measured values are faithfully stored in a database is used, while when calculating the discharging characteristic, the first OCV characteristic is used. It is characterized in that the second OCV characteristic as shown in FIG. 21 (b) in which the OCV characteristic is smoothly approximated and made into a database is utilized.

If it is determined that the OCV measurement process is started during the period when the load current is intermittently supplied from the secondary battery 12 as shown in FIG. 24, the current is not flowing during the period. The envelope curve of the voltage change is obtained, and the OCV is estimated from the convergence value of the envelope curve.

Further, for each charge rate, the relationship between the battery temperature and the decrease rate of the full charge capacity as shown in FIG. 22 is provided in advance as a database for correction, and the supply of the load current from the secondary battery 12 is substantially stopped. When it is determined that the charged state has continued, for example, when it is determined that the OCV lasted longer than the time required to stabilize, the charging rate is estimated from the measured voltage value and the OCV characteristic, while the charging rate is estimated. Then, from the change in the battery temperature and the charging rate, the correction processing of the full charge capacity can be performed by using the correction database.

If it is determined or assumed that the current flowing through the secondary battery contains a surge current, the discharge characteristic in consideration of the surge current is estimated, and the remaining time is calculated based on the discharge characteristic. It is also possible to do so.

Further, the battery capacity detecting device 10 according to the present invention.
As shown in the basic configuration of FIG. 1, a secondary battery 12 including one or a plurality of unit cells and an electric device 18 to which power is supplied from the secondary battery 12 are provided. Is applied.

The secondary battery 12 and the entire battery capacity detecting device 10 may be integrally provided in a case to form the battery pack 16, or data processing such as a one-chip microcomputer forming the battery capacity detecting device 10 may be performed. It is also possible to disperse some or all of the means in the electric device 18 and the rest in the battery pack 16.

The battery capacity detection device 10 uses data on the charging / discharging of the secondary battery 12 and is capable of calculating the current remaining capacity of the battery in real time by the calculation of the microcomputer.

The database 2 relating to charging / discharging of the secondary battery 12 is separately provided in the unit cell database 6 and the battery pack database 4, and a part of the unit cell database 6 or the battery pack database 4 is provided. The database 4 can be replaced for each type of battery pack or each type of unit cell.

Further, the unit cell database 6 holds data relating to unit cells, while the battery pack database 4 holds data capable of specifying the combination state of the unit cells and the storage state in the case, The feature is that the data of the entire battery pack can be derived using the data of both databases 4 and 6.

The unit cell database 6 includes data on the values of each element forming the equivalent circuit of the unit cell as shown in FIG. 4 and data on the OCV characteristics. On the other hand, in the database 4 of the battery pack, data regarding the combination of the unit cells, data for correcting the element value according to the capacity change of the unit cells, and data regarding heat generation due to the storage state of the unit cells in the case. And the resistance value of the electronic circuit of the battery pack.

The battery capacity detecting device 10 uses the unit cell database 6 and the battery pack database 4 to estimate the discharge characteristic of the battery pack, and the discharge characteristic estimating means 7.
The charge / discharge amount detection means 8 for detecting the voltage value and charge / discharge current of the secondary battery 12 to detect the charge / discharge amount, and the remaining battery amount calculated from the estimated discharge characteristic and the detected charge / discharge amount. It is provided with a battery remaining amount calculating means 9 that enables the battery remaining amount.

The above-mentioned discharge characteristic estimating means 7 raises the temperature inside the battery pack due to the current flowing through the resistance component constituting the secondary battery 12, and the current value based on the resistance component changed by the temperature rise. By sequentially calculating and, it is possible to derive the discharge characteristic determined by the OCV, the resistance component, and the current value.

The calculation of the discharge characteristic in the discharge characteristic estimating means 7 is performed for each minute change in the charging rate.
The second current after the change of the charging rate is calculated from the temperature increase calculated assuming that the first current before the change of the charging rate is maintained, and the second current is used to calculate the second current after the change of the charging rate. It can be derived by correcting the current value.

In the above-mentioned discharge characteristic estimating means 7, the data indicating the efficiency of the power source of the electric equipment 18 to which the battery pack 16 is connected is used as the data used for estimation, and the discharge including the efficiency with respect to the battery output is performed. It is also possible to calculate the characteristics.

[0025]

As described above, according to the present invention, the OCV characteristic for detecting the charging rate faithfully stores the measured value in the database, while the OCV characteristic for calculating the discharge characteristic is a smooth approximation of the measured value. By using the data as a database, it is possible to perform a more accurate estimation operation of the remaining amount while suppressing the amount of data in the database to a necessary minimum.

Furthermore, in a load state in which a load current is intermittently supplied, an envelope curve of voltage change during a period in which no current flows is obtained, and the OCV is calculated from the convergence value of the envelope curve.
By estimating the above, it is possible to relatively accurately estimate the charge amount even when used in a device such as a mobile phone that is driven and stopped during standby.

Further, a database of the relationship between the battery temperature and the reduction rate of the full charge capacity with respect to each charging rate during the leaving period of the battery is made into a database in advance, and the full charge capacity is corrected in addition to the charging rate during the leaving period. As a result, it is possible to accurately perform capacity correction especially when the device is left at a high temperature.

Further, in a usage environment where a surge current is likely to occur, the discharge characteristic in consideration of the voltage drop due to the surge current is estimated, and the remaining time is calculated based on the discharge characteristic to calculate the remaining time due to the surge current. The time can be corrected more accurately.

This is an effect obtained from the fact that the battery internal resistance and the like can be obtained from the database, and therefore the amount of voltage drop due to the surge current can be estimated. In particular, when the internal resistance increases due to deterioration, it is possible to obtain accurate results. You can estimate the remaining amount.

Furthermore, the data provided for detecting the remaining battery level is separated into those relating to the unit cells and those relating to the battery pack itself relating to the combination of the unit cells, and the necessary data relating to the assembled battery are separated from both data. By being configured to be calculated by calculation, it is possible to deal with battery packs of various specifications simply by exchanging data regarding the battery packs.

Further, the temperature rise is estimated from the hypothetically determined current value, and the change of the element value and the current of the secondary battery is derived from the temperature rise, and the derived current value is derived earlier. By repeating the operation of correcting the current value, even if using a data processing means with inferior operating capacity,
The discharge characteristics can be estimated efficiently in a short time by using a small amount of reference data.

When the battery temperature is estimated, the temperature change characteristic can be estimated relatively accurately by calculating the magnitude of the temperature rise in consideration of the heat generated by the entropy change.

Further, when the battery capacity detecting device is integrally provided in the battery pack, by providing a dedicated power source for driving the detecting device, it is not necessary to consider the consumption of the battery due to the detection, and the battery remaining The amount can be detected more accurately.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The battery capacity detection device 10 according to the present invention has an OCV of about 4.2 when fully charged.
Full charge capacity is about 1600 at V without deterioration
A more detailed description will be given by taking a unit cell of a mAh lithium-ion battery and a battery pack as an assembled battery in which a plurality of unit cells are combined, as an example. However, other types of secondary batteries can be implemented in substantially the same manner. Is.

In the present invention, regarding the secondary battery 12 whose battery capacity is to be detected, the OCV illustrated in FIG.
The characteristics are measured in advance. Utilizing the fact that the OCV characteristic is maintained substantially constant regardless of the deterioration of the secondary battery 12 and the operating temperature, as shown in FIG. 2B.
The basic configuration is to estimate the charging rate a or b at the time of measurement by measuring the open circuit voltage Va or Vb of No. 1 as required.

Regarding the temperature characteristics of the OCV, it was found from the characteristics measurement in various deteriorated batteries that the change in the temperature characteristics itself is small and that the temperature characteristics are substantially constant even if the secondary battery deteriorates. Obtained. Therefore, even if there is a change in temperature, the charging rate can be estimated from the OCV characteristic in which the temperature characteristic is added.

Further, for example, the charging rate immediately before the start of charging is a
In [%], when the charging rate immediately after charging is b [%], the "difference charging rate" obtained by subtracting the charging rate immediately before charging from the charging rate b immediately after charging is the secondary charging rate during charging. It is caused by being charged by the "charge amount" obtained by integrating the charging current supplied to the battery.

Therefore, by dividing this charge amount by the differential charge rate and further multiplying it by 100, the total capacity at the time of full charge (hereinafter, referred to as "full charge capacity") is maintained until the full charge state. Calculated without.

Therefore, so-called full charge learning, which is conventionally performed, such as measurement of charge capacity by measuring the amount of charge from the end of discharge to the end of full charge, or the amount of discharge from the fully charged state to the end of discharge. Eliminates the need to do
Although the full charge capacity can be calculated by the integrated capacity during discharging and the change in the charging rate before and after discharging, it is preferable to estimate the full charge capacity during charging because the current can be integrated due to a transient.

When the full charge capacity is obtained, the full charge capacity is multiplied by the charge rate at the time of measurement to determine the "remaining capacity", that is, how much remaining capacity the secondary battery 12 has. It is calculated without considering the 12 deterioration states.

Therefore, first, in order to obtain the above-mentioned OCV characteristics prior to the above-mentioned operation of detecting the charging rate, the full charge capacity and the remaining capacity, the secondary battery 12 to be subjected to the capacity detection is carried out by the following method illustrated in FIG. Charge and discharge.

That is, by confirming that the terminal voltage of the battery has dropped below the set value, the time t1 at which the remaining capacity of the battery is considered to have become zero or close to it.
Therefore, in a steady state where the ambient temperature is room temperature (25 ° C),
By continuously integrating the charging current amount for each minute time, charging is performed while continuously checking the changes in the charging amount and the battery voltage.

Immediately after the start of charging, for example, 1
Constant current charging of 600 mA is performed, and charging is continued for 3 hours, for example, under the condition of switching to constant voltage charging of 4.2 V at time t2 when the battery voltage reaches the set value. Rechargeable battery 12 before the end
The total charge amount supplied to is stored as the initial value of the full charge capacity.

Regarding the OCV characteristic, for example, the charging / discharging is stopped every time 10% of charging or discharging progresses, and the OCV at that time is measured, and the charging rate and the OCV at each measurement point are sequentially set as a pair. By saving, a graph as shown in FIG. 2A can be obtained.

By the way, the voltage that actually appears between the terminals of this type of secondary battery 12 is the above-mentioned OC during charging.
It is known that it is higher than V and lower than OCV at the time of discharging. Furthermore, the value of the voltage is not constant in time and decreases or increases with a predetermined time constant.

Such a phenomenon is generally explained by an equivalent circuit for the secondary battery 12 illustrated in FIG. That is, among the elements constituting the equivalent circuit, the solution resistance R interposed in series has a fast response characteristic of the order of milliseconds, and the charge transfer resistance r connected in parallel with the electric double layer capacitance C has the order of seconds. Since it has the response characteristic of
If it waits about 0 seconds, it will converge.

On the other hand, the polarization voltage Ep has a time-order response characteristic, and it takes several hours to several days for the value to stabilize. Therefore, at least several hours are required for accurate OCV measurement. If possible, a rest period of about 8 hours is required.

However, in the actual usage of the secondary battery, except that a relatively long rest period is often provided immediately after the end of charging, other than that, there is a gap between energization and rest, especially during discharging. It is usually repeated frequently, with a break period of several hours, not just eight hours, for OC.
Even measuring V is difficult.

By the way, as shown in FIG. 5, the secondary battery 1
If the reciprocal of time t or the reciprocal of the square root of time t after stopping the energization of 2 is taken on the horizontal axis, plotting the OCV at each measurement on the vertical axis, the locus can be approximated to a straight line or a straight line It becomes a nice curve. Therefore, in the present embodiment, the OCV at two points is measured at a predetermined time interval, and the two points are connected by a straight line as shown in FIG. Is configured.

Since the time after the energization of the secondary battery described above is relatively stable at room temperature, two points after 30 minutes and two hours may be set as the measurement time points. It is possible.

However, since the estimation accuracy can be improved as the time elapses longer, for example, 3 after the end of charging / discharging.
If the first estimation is made by measuring the voltage at two points of 0 minutes and 2 hours, and if the resting state continues for 4 hours or 8 hours, the measured voltage at that time is used for the second or The third estimation is performed and the estimated value is updated.

By the way, if the charging rate at that time is higher than the normal temperature and the charging rate is high, the voltage drop due to self-discharge is larger than that under other conditions. Accuracy is reduced. Therefore, in that case, it is preferable to finish the estimation of the convergence value of the OCV at the time when two hours have elapsed and use the value for the capacity determination.

On the contrary, under low-temperature use conditions, the self-discharge amount during the rest period is small, but the inflection of the voltage locus increases more than at room temperature, and it takes a long time for the OCV to stabilize. It is preferable to estimate the convergence value at two points of 2 hours and 8 hours.

The time interval and the number of times of measurement for the OCV measurement and the convergence value estimation described above are merely examples, and it goes without saying that they can be changed appropriately. For example, when the rest period exceeds 24 hours and continues for a long time, it is estimated that the OCV has already converged. Therefore, the charging rate is immediately obtained from the voltage value measured without performing the above estimation process. On the other hand, it is also possible to correct the decrease in the full charge capacity during the neglected period by using the database. The details will be described later.

On the other hand, not only during continuous charging / discharging, but also when charging / discharging is restarted before 2 hours, which is the minimum rest period for which OCV can be estimated after charging / discharging is stopped, has elapsed. If so, the estimation cannot be performed by the above method, or even if the estimation is possible, the error included in the obtained OCV is large.

Therefore, in the present embodiment, the charge amount is continuously measured by integrating the current value flowing in the secondary battery 12 during charging / discharging, and the charge rate before the start of charging / discharging is measured. The charge rate and the remaining capacity at the present time can be calculated by integrating the change in the charge rate converted from the charged amount.

By utilizing the OCV characteristics as described above, the charging rate and the remaining capacity at the time of measurement or estimation can be detected relatively accurately regardless of the deterioration of the secondary battery 12 and the usage state. The remaining capacity detected by this method is based on the assumption that the amount of Coulomb input to the secondary battery 12 can be completely consumed.

That is, it corresponds to the remaining capacity in the case of a very small current, and when the load is connected, all the remaining capacity detected by this method cannot be discharged, so the remaining capacity when the load is connected is It needs to be calculated separately.

However, it can be detected as a full-charge capacity without load under ideal conditions, and this capacity can be evaluated as one of the full-charge capacity of the battery. In view of this point of view, the present application clarifies and handles the full charge capacity when there is no load and the remaining capacity when there is a load.

This is because the full charge capacity in the case of no load detected as described above is simply treated as the full charge capacity of the battery, and the remaining amount is uniformly estimated by the charging rate based on this full charge capacity. It is possible to build a remaining capacity detection method that enables accurate estimation of the remaining capacity by constructing a database of, calculating the discharge characteristics when there is a load based on this database, and estimating the remaining capacity from this discharge characteristic. It is possible.

Therefore, the remaining amount estimating method of the present invention will be described below starting from the explanation of how the discharge characteristics are determined.

First, in an actual use situation, as can be seen from the equivalent circuit shown in FIG. 4 and the characteristic shown in FIG.
From the ideal battery E whose voltage value changes according to the characteristics, the solution resistance R which is the internal resistance of the secondary battery 12 at the time of discharging
The voltage value obtained by multiplying the charge transfer resistance r by the load current I and the polarization voltage Ep are subtracted and output between the terminals.

However, in actual use,
As can be seen from the equivalent circuit shown in FIG. 4 and the characteristics shown in FIG. 6, from the ideal battery E whose voltage value changes according to the OCV characteristics, at the time of discharging, the solution resistance R which is the internal resistance of the secondary battery 12 and the charge transfer. The voltage value obtained by multiplying the resistance r by the load current I and the polarization voltage Ep are subtracted and output between the terminals.

Further, the element values of the solution resistance R, the charge transfer resistance r, and the polarization voltage Ep of the secondary battery 12 increase as the deterioration progresses due to repeated charging / discharging, and as a result, the battery extracted from the secondary battery 12 is discharged. The voltage value also tends to decrease.

On the other hand, the discharge characteristics of the secondary battery 12 are shown in FIG.
As illustrated in (a), it decreases while showing a substantially straight line during a high charging rate period, but generally has a tendency that the voltage drop abruptly becomes sharp below a certain voltage value Vs.

However, it is not appropriate to use the electric device 18 within such a battery voltage fluctuation range, and if the discharge further proceeds, it is likely that the battery will deteriorate rapidly due to an over-discharged state. .

Therefore, usually, in many cases, the final voltage Vt is set in the middle of the variable region and the discharge is forcibly stopped at the final voltage Vt. Therefore, the remaining time that can be actually used when the secondary battery 12 is connected to the load (hereinafter, referred to as “remaining time”) from the start of discharging until the battery voltage reaches the final voltage Vt.
Is important for using the secondary battery 12 in an electric device, and it is preferable that the remaining time can be accurately grasped at any time such as immediately after turning on the power of the electric device.

By the way, when the usage conditions such as load current and ambient temperature are constant, the remaining time is determined by measuring the discharge characteristics in advance and detecting the battery voltage when the remaining time is detected. be able to.

However, the battery voltage at the time of actual discharge is caused by the presence of the above-mentioned polarization voltage Ep.
As illustrated in FIG. 6B, when energization starts at time t11, the value of OCV gradually decreases, and at time t12, the theoretical discharge characteristics match, and the terminal voltage of the secondary battery 12 is simply changed. It is difficult to obtain the remaining time only by detecting it.

Further, the discharge characteristics of the secondary battery 12 are shown in FIG.
When the load current is changed as shown in FIG.
When the secondary battery 12 is deteriorated as shown in FIG.
As shown in (c), even if the ambient temperature of the secondary battery 12 increases / decreases, it greatly changes, so that it is almost impossible to prepare discharge characteristics under all usage conditions.

Therefore, in the present invention, the element value of each element shown in the equivalent circuit of the secondary battery 12 is individually measured as shown in FIG. 9 using the method described below, and the value is stored in a database. The remaining time is estimated by deriving the discharge characteristic by calculation using the stored value at the next discharge.

Here, in this embodiment, the solution resistance R and the charge transfer resistance r shown in FIG. 4 have relatively fast transient responses, but the response speeds of the two are different, and FIG. Measurement is performed using the transient response method shown in.

That is, when a unit current composed of a step-shaped constant current as shown in FIG. 8B is applied to the load by the signal output from the measurement control means shown in FIG. 8C, the voltage drop VR due to the solution resistance R having a fast response speed is first detected at the time of rising of the current.

After that, a voltage drop Vr due to the charge transfer resistance r is generated at a predetermined time constant τ (≈C · r). For example, when a time of about 10 seconds has elapsed from the start of energization, the voltage value after that is substantially linear. Become a state. Therefore, by extending the straight line to the charging start time, the voltage drop VR due to the solution resistance R and the voltage drop Vr due to the charge transfer resistance r are separately detected.

The solution resistance R and the charge transfer resistance r, which are the internal resistances of the secondary battery 12, are measured by the above-mentioned OCV.
The graphs shown in FIGS. 9A and 9B can be obtained by performing the measurement at the same time as the characteristic measurement, and by making a pair with the charging rate of every 10% and storing the data in a database.
Set it as the initial value. Further, it is measured at an appropriate time such as a rest time at the time of discharging, and the value is normalized by converting it to the normal temperature and stored together with the charging rate at the time of measurement.

On the other hand, it is difficult to directly obtain the value of the polarization voltage Ep. However, FIG. 6 (a)
As shown in, the voltage value obtained by subtracting the battery voltage from OCV coincides with the voltage component due to the internal resistance of the secondary battery 12 and the polarization voltage Ep, for example, at the time of discharging. Since it can be directly detected by the method described above, by subtracting the value, a graph like FIG. 9C showing the relationship of the polarization voltage Ep at each charging rate can be calculated.

However, since the polarization voltage Ep has a very long polarization time constant, the current condition is stable after the start of charging shown in FIG.
For example, it is preferable to obtain it by a change in battery voltage after about 3 to 5 minutes.

Since the polarization voltage Ep depends on the ion migration state due to diffusion, the evaluation is performed when a change in the charging rate of, for example, about 3% occurs in addition to the method of determining the evaluation timing with the passage of time. There is also a way to do it.

However, since it depends on the diffusion rate of the battery and the like, more accurately, it is desirable to change the measurement timing according to the degree of deterioration, the current, the temperature, the change in the charging rate or the amount of change over time. In that case, as a method to find the timing,
Data of discharge condition vs. measurement timing was collected in advance by detecting the time when the polarization becomes almost constant from the behavior of voltage change after the start of discharge under various conditions such as discharge current, and by detecting the change in charging rate. By obtaining the measurement timing from the database, the polarization voltage Ep can be evaluated more accurately and in a short time.

Alternatively, since there is a portion that shows a similar change characteristic of the polarization voltage Ep due to a constant change in the charging rate regardless of the current, it can be obtained by a change in the voltage when a constant change in the charging rate occurs. It is possible.

Here, the OCV during charging is the OCV corresponding to the charging rate converted from the charging amount obtained by integrating the current value with the value measured at the end of the last discharge before charging.
It can be calculated by adding the estimated values of

The values of the solution resistance R and the charge transfer resistance r are
Basically, the above method is used. However, when the OCV is calculated, the DC resistance is measured under the condition that the charging is turned off and the charging current is zero at the same timing, or the transient response due to the switching of the constant resistance load during charging is used. Can be measured.

When the charging rate at the start of charging is small, the OCV also changes rapidly as the charging progresses and the charging rate increases, and the error is large. Therefore, the polarization voltage Ep near the start of charging can be estimated in more detail by charging the battery with a current smaller than usual for a certain period of time until it exceeds a predetermined charging rate and by utilizing the change in the battery voltage during that period.

Here, when charging is performed by switching the charging method from constant current charging to constant voltage charging at time t2 in FIG. 3, the change in battery voltage is directly measured during the constant current charging period. And used to estimate the polarization voltage Ep.
However, when it enters the region of constant voltage charging, the change in charging current is measured, and the change in current is converted into a voltage change for evaluation, which is used for estimating the polarization voltage Ep.

As described above, the values of the solution resistance R, the charge transfer resistance r, and the polarization voltage Ep forming the equivalent circuit of the secondary battery 12 are obtained in correspondence with the change of the charging rate as shown in FIG. Therefore, these values are set as initial values of element values showing the characteristics of the secondary battery 12 and stored in a database.

Although the method of simply measuring the battery alone or utilizing charge / discharge has been described above, it goes without saying that there is another method for continuously obtaining the characteristic. As an example, it is also possible to continuously change the load current in a pulse shape and obtain it from the response.

In this case, if the load is intermittently switched at intervals of, for example, 10 seconds, and a constant load current is superimposed with a load current of a rectangular wave pulse having a cycle of 20 seconds, a load current for measurement shown in FIG. ), A rectangular response waveform like this is obtained continuously. Since the difference between the two envelopes passing through the upper and lower outermost portions of this waveform is the sum of the voltage drops of the solution resistance R and the charge transfer resistance r, if the solution resistance R is separately calculated, the charge is continuously obtained every 10 seconds. The magnitude of the movement resistance r is obtained.

Since the solution resistance R has almost no dependency on the charging rate, a separately measured value may be used, or a short rectangular wave pulse current of the order of microseconds may be applied to the load current and the value may be determined from the response. . Of course, it goes without saying that it may be obtained from the voltage and current changes at the moment when the rectangular wave pulse at 10-second intervals changes, but here, an example is given in which measurement is performed with a dedicated measurement pulse.

Since the difference between these two envelopes is the voltage drop due to the charge transfer resistance r and the solution resistance R with respect to the rectangular wave pulse current, it is assumed that the rectangular wave pulse current increases by the average load current during measurement. If the difference between envelopes is increased, the difference is the charge transfer resistance r and the solution resistance R due to the average current.
Corresponds to the voltage drop of. Therefore, the portion between the characteristic curve obtained by subtracting the found voltage drop from the OCV characteristic and the discharge characteristic curve can be evaluated as the voltage drop due to polarization, so that the database can be easily generated.

On the other hand, regarding the temperature dependence of each element value in the secondary battery 12, as shown in FIG. 10, when the horizontal axis is the reciprocal of the absolute temperature and the vertical axis is the logarithm of the resistance value, for example, it is a substantially straight line. Can be approximated to a predetermined shape such as. Therefore, the temperature characteristics for each element value described above are measured in advance and stored.

When the secondary battery 12 is actually used, the temperature of the element value is corrected from the ambient temperature of the secondary battery 12 at the start of discharge, and the voltage drop caused by the element value is calculated from the value of the load current. By correcting the current for
The discharge characteristics of the secondary battery 12 under the usage conditions are calculated.

On the other hand, since the charging rate is always integrated and grasped, the discharging current immediately after the start of discharging or the discharging power which will be described in detail later changes from the charging rate and the calculated discharge characteristics at that time. The remaining time is estimated on the condition that it lasts without doing anything.

Further, in the discharge characteristic, the area between the curve of the discharge characteristic and the output voltage zero, which is divided from the current charge rate to the final charge rate, that is, the area under the discharge characteristic curve ( The shaded portion in FIG. 6B) corresponds to the electric power output from the battery. Therefore, it is possible to estimate the remaining power of the battery from this characteristic.

For that purpose, first, the area of the lower portion is obtained as the area under the discharge characteristic. Next, the discharge charge amount from the present to the end is obtained by multiplying the full charge capacity by the difference between the current charge rate and the end charge rate. After that, the remaining power is estimated by multiplying the area under these discharge characteristics and the discharge charge amount. The residual power thus obtained faithfully reproduces the discharge characteristics, and is a highly accurate residual power estimation method.

Further, although it is necessary to correct the discharge characteristic by the temperature characteristic, the temperature actually rises due to the internal resistance loss of the battery during discharging. This is almost determined by the battery pack and ambient conditions, so the temperature characteristic change when discharged at a constant current is stored in the database together with the charging rate.
Alternatively, by estimating from temperature resistance and heat capacity together with the charging rate and further improving the estimation of the temperature dependence of the discharge characteristics at each charging rate, highly accurate remaining time estimation and remaining power estimation are possible. .

Next, in the following, as a method for evaluating the polarization voltage Ep, which is the voltage drop due to the above-mentioned polarization, the resistance value is evaluated instead of the voltage.
The temperature-dependent element also does not depend entirely on the database,
An example in which calculation is possible is shown. Since the polarization voltage Ep is generated by diffusion, the voltage has a current dependency. Therefore, the diffusion resistance Zw is assumed as a resistance component that causes a voltage drop due to polarization due to the current dependency, and the remaining amount is estimated using this.

Here, the diffusion resistance Zw is defined and used because it acts as a resistance component even when a current flows through the Warburg impedance Zw of the internal equivalent circuit of the battery. This resistance value collectively indicates the components that cause a voltage drop other than the solution resistance R and the charge transfer resistance r.

Since the voltage drop due to diffusion has a current dependency, the diffusion resistance Zw is often not expressed as a constant resistance component. In such a case, a database of the diffusion resistance Zw considering the current dependency is constructed by measurement in advance, and then the polarization voltage Ep can be measured at appropriate time as described above. Therefore, the diffusion resistance Zw can be calculated simultaneously with the measured current. By calculating and correcting, the diffusion resistance Zw with current dependency is used for estimation of the remaining amount. In addition, it goes without saying that the polarization voltage Ep can be made into a database as it is without using the diffusion resistance Zw and the value can be used at the time of calculation.

Next, FIG. 11 shows an example of a circuit configuration of a capacitance estimation circuit including an equivalent circuit model for obtaining a discharge characteristic in consideration of temperature dependence and its surroundings by using the above diffusion resistance Zw. Hereinafter, according to this model example, a method of estimating discharge characteristics when discharged at constant power, and
A method for obtaining an estimated value of the remaining power amount obtained from that is shown, and an example of the remaining amount estimation processing as a capacity meter when this model is used for remaining amount estimation will be described.

Even in this example, the equivalent circuit of the battery is shown in FIG.
However, in order to show the temperature dependence, the heat balance equation considering entropy in the "heat generation analysis of small lithium-ion secondary battery" proposed by Kameyama et al. A thermal change calculation formula suitable for the discharge characteristic simulation of a microcomputer is obtained and used for temperature estimation.

The battery heat generation model in consideration of the entropy described above is Qp for heat generation due to overvoltage, Qs for heat generation due to entropy change, and Qb, O for heat generation around the battery.
CV temperature change is dVo / dT, battery temperature is Tc, ambient temperature is Tr, battery heat capacity is Cc, discharge current is I, overvoltage resistance from VI characteristic of constant current discharge is Rη, Faraday constant is F, When the battery surface area is A and the heat transfer coefficient is h, Qp = I ² · Rη, Qs = −Tc · ΔS · (I /
F) =-Tc (dVo / dT) * I, Qb = -A * h *
(Tc-Tr), and the heat balance equation is Cc · (dTc /
It is pointed out that dt) = Qp + Qs + Qb.

From the above heat balance equation, if the battery temperature rises by ΔTc in a minute time Δt, then Cc · ΔT
It can be expressed as c / Δt = Qp + Qs + Qb, and from this, ΔTc = Δt · (Qp + Qs + Qb) / C is obtained.

Therefore, Tc, I, dVo / of each item
By obtaining Qp, Qs, and Qb from dT and Rη,
Since ΔTc is obtained and the estimated temperature is Σ (ΔTc) + start temperature, the temperature change value is obtained by the integrated value of ΔTc,
The temperature is estimated by integration with the starting temperature.

Further, the element value of the battery changes depending on the temperature,
Further, the temperature and the like change due to the change of the element value, and the current value in that case is obtained by the following conditions. The discharge characteristic satisfying this condition is the desired discharge characteristic.

First, the values of the solution resistance R, the charge transfer resistance r, and the diffusion resistance Zw, which are the element values of the battery, are measured in advance using the temperature T, the charging rate Q, and the current I as parameters, and are stored in the database in advance. It can be derived by knowing the temperature T, the charging rate Q and the current I at the time point.

If the power consumption W of the load is constant, W
= I * (open circuit voltage- (R + r + Zw) * I), the current value I is calculated by calculation when the OCV, the element value, and the used power W at the start of discharge are known.

Further, the change time Δt required for the charging rate Q to change by a minute amount ΔQ is obtained by “ΔQ × full charge amount / average current”.

By the way, it is not impossible to directly calculate the discharge characteristics by solving the above relational expressions simultaneously. For example, a method of expanding and solving to a first-order simultaneous polynomial, etc. can be considered.

However, normally, in order to reduce the cost of the capacity meter for estimating the remaining amount, it is the mainstream to estimate the capacity by using a one-chip microcomputer or the like having a small calculation power. Therefore, it is considered that conditions such as a small amount of calculation at one time and low memory consumption are necessary.

Therefore, in the present embodiment, the value of the next point is calculated assuming that the difference between the calculation start point and the value of the next point is small, and the next point is recalculated using the calculation result. Therefore, an example of a calculation method is used that enables the estimation of the curve indicating the discharge characteristic while minimizing the use of the database while improving the accuracy.

That is, the first characteristic point, which is the starting point, and the second characteristic point when the charging rate slightly changes from the first characteristic point, are repeatedly obtained by using the above relational expression to obtain the discharge characteristic and the temperature characteristic. Is required. The point of the calculation here is to simulate the discharge characteristic by first correcting other parts based on the value that is decided for the time being.

Further, by separately providing a database for the above unit cells and a database for a battery pack such as a case or a battery configuration similar to thermal resistance,
The remaining amount can be estimated by estimating the discharge characteristics in consideration of deterioration, temperature, etc., using a smaller database.

That is, when a capacity meter corresponding to various battery packs is constructed from a database, it is possible to incorporate a database of unit cells and a database of battery packs corresponding to a target battery pack.

Here, when comparing the sizes of the databases, the size of the database increases because the database relating to the unit cells usually needs details such as current dependence. On the other hand, the database regarding the battery pack is usually a connection configuration of the unit cells of the battery pack, for example, “2S3P” (a configuration in which two parallel connections of three unit cells are connected in series, where S is a series and P is a The database does not increase because it contains only the thermal resistance and heat capacity determined by the type of parallel), the battery pack case, etc., and other values.

Therefore, by inserting a database relating to the battery pack into a memory such as an EEPROM which is a data reading source of the microcomputer and updating only the data relating to the battery pack each time the configuration of the battery pack is changed, the microcomputer itself can be updated. It is possible to configure a capacity meter corresponding to various battery packs without making any changes.

Of course, as described above, the value for correcting the cell battery database is put in the EEPROM or the like, and the cell type can be changed so that the capacity type corresponding to various battery packs can be constructed. is there.

Although the battery temperature is determined in consideration of entropy in the above embodiment, the temperature rise characteristic may be incorporated in the discharge characteristic calculation based on the discharge rate-temperature characteristic. Needless to say.

Further, when the discharge power is used as a parameter and the maximum temperature at the end of discharge is normalized on the horizontal axis of the charging rate, the temperature characteristic becomes a substantially constant pattern. Therefore, the discharge characteristics can be estimated without significantly increasing the size of the database.

Further, the discharge characteristic is estimated on the assumption that the battery pack is used with a constant power, but the original power consumption value is originally the main unit in which the battery pack is mounted. The capacity meter calculates from the database of the battery based on the notification from the electric device 18,
It may differ from the actual power used. Therefore, when the actual power usage and the reported power deviate by a certain amount or more, it is desirable to estimate the remaining power from the actual power usage. In that case, it is also desirable to notify the parent device of that fact.

Although the calculation conditions, the calculation method, and the method examples of cost reduction and the like have been described above, FIG. 12 schematically shows an example of curves of the discharge characteristic and the temperature characteristic and the conditions for determining the characteristic. The calculation points of the discharge characteristic calculation processing method described below are shown more specifically.

As a calculation point, the first point is obtained as described above, and then the second point at which the charging rate is changed is obtained under the condition that the condition does not change significantly.

Now, assuming that the first point is the point at which the discharge starts, the ambient temperature Tr is measured as the temperature,
The temperature in this case is used below as the battery temperature Tc.

The output voltage at the first point is the voltage drop V1 due to the internal resistance and current of the battery pack and the voltage drop V due to the load of the electric device 18 provided as the master unit.
The sum of 2 and OCV is OCV.

Next, at the second point when the charging rate ΔQ changes, if the current at the first point flows, the time Δt to the second point is known.
The temperature increase ΔTc is calculated and the battery temperature Tc at the second point is calculated. Further, since the battery temperature Tc and the current I are known, the internal resistance and the like are obtained, and the voltage / current at the second point is obtained.

However, as it is, the calculation result of the second point is not reflected in the second point. Therefore, the calculation result of the second point is further input, and the values of the discharge characteristic and the temperature characteristic of the second point are calculated again. To do. By doing so, the accuracy of the simulation is improved.

Next, when the second point is obtained as described above, this is set as a new first point, and similarly to the case where the second point is obtained from the above-mentioned first point, a new second point is obtained. Calculate the state. By continuing this, the curve of the discharge characteristic and the temperature characteristic can be obtained. Finally, the discharge voltage is a predetermined discharge end voltage V
By continuing until t or less, the entire discharge characteristic is obtained.

Although the internal resistance has been described based on the charge transfer resistance r inside the battery, the battery pack is
Since there is internal wiring resistance, etc., it is necessary to make a voltage drop corresponding to the resistance including it. Furthermore, it is necessary to obtain the resistance component based on the database of the battery pack configuration.

For example, in the case of 2S1P, the internal resistance of the battery is double the resistance of one unit cell, and the OCV characteristic is double the value. Not to mention that there is. Furthermore, in the case of 2S3P, the unit cell 2 ×
1/3 = 2/3, which is equivalent to 2 unit cells as the OCV characteristic.

Therefore, as the database of the battery pack, the circuit resistance rc is measured in advance, and the sum of the measured value and the internal resistance of the battery obtained from the connection configuration of the unit cells is taken as the resistance, and the OCV characteristic is the series connection of the batteries. Just take minutes. Since this conversion formula itself can be easily processed based on the combination data of the unit cells, it can be applied to any battery pack if it is incorporated in the software of the microcomputer in advance.

An example of the configuration method in such a case is shown in FIG. In the figure, a battery cell database 6 and a battery pack database 4 are provided, and by storing the battery pack database and the like in a rewritable memory such as an EEPROM, the specification change of the battery pack can be flexibly dealt with.

Next, FIGS. 13 to 15 are flowcharts showing the processing method for obtaining the discharge characteristic, which will be described more specifically below with reference to FIG. 13 is a flow chart showing the overall flow during discharging, FIG. 14 is a flow chart for obtaining the first step A in FIG. 13, and FIG. 15 is a flow chart for obtaining the second step B in FIG.

When the discharging is started in FIG. 13, first, the charging rate Q1 at the time of starting the discharging and the power consumption W notified from the electric device 18 are detected, and the charging rate Q1 and the data in the database are used for charging. OV corresponding to rate Q1
After C is derived, the process of calculating the current value at the first point is started.

The calculation process of the first point shown in FIG.
It shows the calculation method when it is unknown what kind of element value or current value will be obtained at the start of discharge. First, from the charging rate to OCV
Then, the following conditions are set assuming that it directly determines the current.

That is, when the discharge is started, the used power W
And the provisional first current determined only by the values of OCV is calculated by "W / OCV". Further, it is assumed that the battery temperature Tc at the start of discharge is substantially equal to the ambient temperature Tr, and the first element value is derived from the first current and the value of Q1 using the estimation database.

Here, when the current I is determined, the element value is derived from the database, and when the element value is determined, W = I × (O
Since the current is calculated from the relationship of (CV-I × element value), the derivation of the element value and the calculation of the current using the derived element value are repeated a plurality of times (twice in this embodiment). By performing the current correction, the current I1 at the first point is estimated.

As described above, the first
When the current I1 at the point is estimated, the process proceeds to FIG. 15 and the step of estimating the current value I2 at the second point where the charging rate is decreased by the constant charging rate ΔQ is executed.

Here, since the current and the like are still unknown at the second point, first, assuming that the current I1 at the first point continues, the arrival time and temperature are obtained. The arrival time Δt required for the charging rate Q to change by a minute amount ΔQ
Is “ΔQ × full charge / I1”, the temperature change amount ΔTc that rises due to the change in the charging rate of ΔQ is Δt · (Qp + Qs
+ Qb) / C, and the battery temperature Tc at the second point is obtained.

Further, when the battery temperature Tc is known, the element value is derived from the database, and the derived element value is used to recalculate the current, whereby a more accurate second point current I2 'is calculated. It

When the current I1 at the first point and the current I2 'at the second point are obtained, it is assumed that the average current "(I1 + I2') / 2" flows up to the second point, and the average current Recalculate the arrival time and the arrival temperature of 2 points.

Furthermore, the temperature calculated from this recalculation is used to obtain the current I2 at the second point, and the calculation of the second point ends, assuming that the state at the second point has been calculated. That is, in the first calculation, the current of the second point is calculated assuming that the current of the first point continues until the second point, and in the second calculation, the current of the second point calculated as the first point is calculated. The current value at the second point is corrected assuming that the average current continues.

Hereinafter, the current I2 at the second point
The current at the next point is calculated by replacing the current I1 at the point. The output voltage is the final voltage Vt
It continues until it becomes the following and obtains the entire discharge characteristic.

Although only the current has been mentioned in the above description, the voltage is immediately obtained when the current is obtained, and thus the description thereof is omitted.

An example of the calculation method has been described above, but it goes without saying that the accuracy can be improved by returning the current finally obtained in the second step to the average current and performing the calculation. There is no.

Further, it is needless to say that the OCV and the resistance are changed according to the battery connection state and the resistance including the wiring resistance of the circuit is obtained from the database regarding the battery pack, etc., but it also becomes a load of AV equipment and the like. It is also possible to improve the discharge characteristic accuracy by calculating the behavior of the parent device.

The efficiency of the power source of the electric device 18 provided as a master unit is also an important factor for improving the accuracy of remaining amount estimation. For example, when the power supply configuration of the parent device is a DD converter, the conversion efficiency of the DD converter varies depending on the input voltage.
If the remaining power is calculated in consideration of the conversion efficiency of the D converter, the remaining time estimation accuracy will be further improved. That is, the used power including the conversion efficiency is obtained as the used power for the discharge characteristic calculation, and this is used for the discharge characteristic calculation.

Normally, since it depends on the input voltage of the DD converter, a database of voltage-to-conversion efficiency is provided, and when estimating the remaining power, the conversion efficiency is added to the target used power to change the size of the target used power. Then, the discharge characteristic curve is estimated.

In this case, it is desirable that the conversion efficiency of the power supply is passed from the master unit to the capacity estimation processing as a database, and as the database itself, data of a pair of voltage and conversion efficiency in that case is within the working voltage range. It is desirable to prepare for several points. As the database, for example, in the case of the battery pack and the parent device, it may be handed over by communication before the start of use of the battery. Needless to say, in such a case, it can be easily realized by deciding the communication specifications.
Needless to say, it is necessary to prepare these conversion efficiency data before estimating the remaining amount. Therefore, when the battery pack is used as a pair, it may be written in advance in the EEPROM or the like of the capacity meter in the battery pack. Alternatively, the parent device may write the database on its own in the EEPROM of the battery pack.

It is considered that the accuracy of the simulation can be improved by further repeating the calculation, but it is necessary to determine it from the calculation amount, the calculation time, the calculation power and the accuracy of the calculation result. It has been confirmed that the calculation result from the actual battery data has sufficient accuracy even in the present method shown in FIGS. 14 and 15.

Further, it is necessary to include the battery configuration, internal resistance, etc. as the battery pack database 4,
The unit cell itself can be configured so that it can be changed. Since the discharge characteristic curve of the unit cell itself substantially depends on the electrode material, even if the size of the battery is changed, the OCV and the like are almost the same, and the charge transfer resistance r and the like due to the change of the electrode area and the like The behavior is similar to the extent that the value changes. Therefore, in the unit cell database 6, data for correcting each element value can be recorded in an EEPROM or the like, and can be configured to cope with changes in the unit cell.

Therefore, by having such a database, it is possible to construct a remaining amount estimation method and device which can flexibly cope with changes in the configuration of the battery pack and the unit cell itself. For example, EEPR having the structure shown in FIG.
It goes without saying that it may be included in the database 4 of the battery pack configured by OM or the like.

In the discharge characteristic estimation, the battery temperature Tc is estimated by the rise from the ambient temperature Tr to improve the accuracy of the discharge characteristic estimation. In this case, however, as the ambient temperature Tr, the discharge is stopped for a long time. The battery temperature Tc before the start of discharge, which is estimated to be the temperature after the elapse,
It is obtained as r and the subsequent temperature rise is estimated.

However, the ambient temperature Tr is rarely used under a constant condition, and when the ambient temperature Tr changes, the battery temperature estimated using the above method and the measured battery temperature are used. There is an error between. Therefore, the change in the ambient temperature Tr can be conversely estimated from the difference between the actual measured value and the estimated value of the current battery temperature Tc. When the change in the ambient temperature Tr is estimated, the changed ambient temperature is used to estimate the discharge characteristic, so that it is possible to estimate the remaining amount corresponding to the change in the ambient temperature.

Specifically, the discharge characteristic calculation is started under the estimation start condition, and the battery temperature Tc and the charging rate at two points, the start point and the present point, are measured, while the current charge estimated at the start point of the discharge is measured. The battery temperature Tc at the rate is estimated by calculation. If the difference between the measured battery temperature and the estimated battery temperature exceeds the set value and is large, it is estimated that the ambient temperature Tr has changed, and the ambient temperature Tr is corrected to the following estimated value.

Here, an example of an equation for calculating the estimated value of the ambient temperature will be shown. This is because the difference (battery temperature error before correction) between the current estimated battery temperature (estimated current battery temperature before correction) obtained from the start of discharge and the currently measured battery temperature (current battery temperature) , The ambient temperature before correction is assumed to correspond to the difference between the ambient temperature before correction (ambient temperature before correction) that was originally measured and saved and the current actual ambient temperature (estimated value of ambient temperature). By adding the electric temperature error before correction to the temperature, first, the ambient temperature assumed to be corrected (ambient temperature after correction) is obtained. Next, based on the corrected ambient temperature, the current battery temperature is estimated again (corrected current battery temperature estimated value), and the final ambient temperature is calculated from these values. The final ambient temperature is (modified ambient temperature-ambient temperature before modification)-(current battery temperature-current battery temperature estimated value before modification) / (corrected current battery temperature estimated value-modified) It can be calculated from (previous estimated current battery temperature) + ambient temperature before correction.

In the construction of the database, it has been described that the value of the resistance component inside the battery is measured by the step response shown in FIG. 8 and the frequency response shown in FIG. 19, but the present invention is not limited to this. Needless to say, nothing.

For example, when the voltage detection accuracy of the A / D converter is low, the A / D converted value is measured many times and the average value thereof is taken to perform high-accuracy voltage measurement to improve the element value detection accuracy. It is possible to

In this case, since the response of the charge transfer resistance r is fast, a short pulse, for example, a square wave of the order of μ seconds is output in the circuit performing the step response of FIG. 8, and the response waveform is turned on and off. The voltage of may be sampled many times to improve the measurement resolution and improve the element value detection accuracy.

Further, since the voltage change in the charge transfer resistance r is slow, it is possible to improve the measurement resolution by increasing the number of times of voltage measurement before energization and voltage measurement during energization. It goes without saying that this method is effective in a microcomputer having low A / D conversion accuracy.

Furthermore, in actual use of the AV equipment, there may be a step-responsive change, and the element value can be obtained from the response in this case. Further, when the current changes in this way, it is possible to obtain the internal resistance from the current and voltage changes and the elapsed time in that case.

In this case, the resistance component for the response of 10 seconds is obtained from the voltage / current change before and after a fixed time, for example, 10 seconds, and this is obtained as the charge transfer resistance r.
Furthermore, the resistance component when the response time is short is evaluated as the solution resistance R by obtaining the resistance component for many time responses. It goes without saying that this corresponds to the frequency analysis of the resistance component and is an effective means when there is a margin in the calculation power and the like.

Although the method of estimating the remaining battery level has been described above, the entire estimated value in the remaining level estimation can be modified, and therefore a detailed description thereof will be given below.

As the secondary battery 12 is discharged,
The estimated remaining power amount and the actually measured power amount (power integrated value) change, but attention is paid to two points during discharging, and the change amount of the estimated remaining power amount at the two points and the measured remaining amount. The amount of change from the electric energy is calculated. In this case, if both changes are equal, it means that the estimated value change and the measured value change during that period are in good agreement, regardless of the discharge process. It is considered to be one proof that

If the two are different, the estimated value and the actual measured value are different, and if the two estimated values are different, the estimated value and the actual measured value are different, and the accuracy of the estimated value is low. Become. Therefore, if the relational expression of the difference of the previous measured value = K × the difference of the previous estimated value is defined as the coefficient K, K = 1 if the estimated value is correct. However, in reality, K = difference between actual measurement values at the previous time / difference between previous estimated values ≈1.

Therefore, if there is no change in the remaining amount estimation algorithm and the estimation is repeated in the same manner, it is expected that "difference of actual measurement value of this time = K × difference of estimated value of this time". That is, it is expected that the difference between the actually measured value and the estimated value that will be obtained by the current discharge will not match.

Therefore, "difference of actual measurement value of this time = difference of corrected current estimation value = K × difference of current estimation value = (difference of previous measurement value / difference of previous estimation value) × estimation of this time It is possible to correct the difference between the estimated values as the “value difference”.

Therefore, assuming that the difference is from full charge to end of discharge, “corrected estimated value of this time = (difference of previous measured value / difference of previous estimated value) × estimated value of this time”
However, it can be expected and the estimation accuracy will be improved.

Actually, the first point is set as the discharge start point, and the estimated value and the power integrated value in that case are recorded.
Using the second point as the discharge end point, record the estimated value and the electric power integrated value in that case, calculate the coefficient K from the four data thus obtained, and correct the remaining amount estimated value for the next time. As a result, a more accurate estimated remaining amount can be obtained as a learning effect.

This can be expected to give good results under the same discharge conditions. Therefore, it goes without saying that when the discharge condition is different from the previous one, by taking measures such as bringing the coefficient close to 1, a remaining amount detection method with high remaining amount estimation accuracy can be obtained in various cases.

[0169]

EXAMPLE Hereinafter, based on the example shown in FIG. 16, a battery capacity detection device 10 having a circuit configuration using the above-described battery capacity detection method, a secondary battery 12, and a battery protection portion 14 are integrated in a case. The configuration of the battery pack 16 stored in the above will be described.
The characteristics of the secondary battery 12 and the battery capacity detection device 10
Since the detection method in 1 is substantially the same as that described above, detailed description thereof will be omitted below.

The battery pack 16 is attached to various electric devices 18 such as AV devices, personal computer devices and mobile phones, and the communication circuit 2 on the electric device 18 side capable of bidirectional communication.
The battery pack 16 shows the battery capacity display operation using the display in the electric device 18 by sending the detection data from the battery pack 16 toward 0.
It is also possible that the display means is integrally provided on the case, and the battery pack 16 independently performs the display operation in addition to the battery capacity detection operation. On the contrary, part of the control operation performed by the battery capacity detection device 10 may be performed by the electric device 18 side.

Secondary battery 1 housed in battery pack 16
2 is configured such that a plurality of unit cells are connected in series or in parallel so that the capacity and output voltage required for the battery pack can be achieved.

Further, in addition to the database 6 of the element values and OCV characteristics of the unit cells, the battery pack database 4 capable of discriminating the difference in the pack state such as the unit cell configuration or the temperature parameter is individually provided.

Here, the battery protection unit 14 includes two FETs 2
A switching unit 24 composed of 2.22 and a protection circuit 26
The switching unit 24 has a configuration substantially similar to that of the conventional configuration in which the switching unit 24 is used by being inserted in series in the energizing circuit extending from the secondary battery 12 to the electric device 18.

That is, the protection circuit 26 is provided with a comparator composed of, for example, an operational amplifier or a comparator and a reference voltage, and can be operated only by hardware without using computer software, so that occurrence of malfunction can be suppressed as much as possible. Improves safety.

Then, the battery voltage of the secondary battery 12 and the magnitude of the load current flowing through the switching unit 24 are constantly checked, and the fact that the magnitude of the load current exceeds the set value and the battery voltage is set. When it is detected that the voltage has dropped below the value, the basic configuration is to send a signal to the switching unit 24 to forcibly stop the energization of the load to prevent the secondary battery 12 from being damaged. However, in the present embodiment, a signal corresponding to the control state is further sent to the battery capacity detection device 10 to notify that the abnormal state has occurred.

The battery capacity detecting device 10 is mainly composed of an external circuit group 28 which performs analog value signal processing, and a control section 30 which uses a one-chip microcomputer as the center of control to perform digital value signal processing. It Then, various measured values output from the external circuit group 28 are output to the control unit 30.
Is sent to the control unit 30 and the program stored in the ROM provided in the control unit 30 is referred to the database 2 to calculate the measured values and the entire operation is controlled by software.

Here, the external circuit group 28 includes the temperature detection circuit 3 which outputs a signal corresponding to the battery temperature Tc of the secondary battery 12.
2, a voltage detection circuit 34 that outputs a signal corresponding to the terminal voltage of the secondary battery 12, a current detection circuit 36 that outputs a signal corresponding to the current flowing through the secondary battery 12, and the secondary battery 1
The load current for detecting the circuit constant of 2 is the secondary battery 12
And a load circuit 38 that flows to

The temperature detecting circuit 32 is provided with a temperature detecting means 40 such as a thermistor close to the secondary battery 12, and converts an analog value output from the temperature detecting means 40 corresponding to a temperature change into a digital value. It is sent to the control unit 30.

The voltage detection circuit 34 is connected to both ends of the secondary battery 12, extracts the voltage output between the terminals, converts the voltage into a digital value, and sends the digital value to the control section 30.
Used to measure battery voltage and OCV.

The current detection circuit 36 converts the voltage value generated across the resistor 44 connected in series with the secondary battery 12 into a digital value and sends it to the control section 30. It is used to measure the flowing current value.

The load circuit 38 is for separating and measuring the solution resistance R and the charge transfer resistance r by the transient response method shown in FIG.
During the rest period in which the energization of 8 is stopped, the switching transistor 42 is turned on by a signal sent from the control unit 30, and the resistors 46 and 44 connected in series with the transistor 42 are energized. The internal resistance of the secondary battery 12 is measured by simultaneously measuring the transient response state of the secondary battery 12 illustrated in FIG. 8B or 8C accompanying this energization with the voltage detection circuit 34 and the current detection circuit 36. It is possible to measure.

In the following, the operation procedure of battery pack 16 will be described in more detail with reference to the flow charts shown in FIGS. 17 and 18.

First, on a predetermined storage means such as an EEPROM, in addition to the OCV characteristics of the unit cell illustrated in FIG. 2, as the unit cell database 6, the discharge characteristics illustrated in FIG. 6 of the secondary battery in the standard state. Each element value illustrated in FIG. 9 is measured in advance, stored as a database as an initial value during normal control.

In this embodiment, at least two kinds of OCV characteristic data stored as a database are provided for calculating the charging rate and calculating the remaining amount. That is, the OCV characteristics actually measured for the unit cell are shown in FIG.
It is common to have a shoulder (inflection point) as shown by the broken line in FIG. Therefore, when estimating the charging rate using the OCV characteristic as it is, by preparing a database that faithfully reproduces the first OCV characteristic in which the measured value is directly stored in the database, the error in estimating the charging rate is minimized. Suppress.

On the other hand, when the discharge characteristics are estimated, FIG.
The curve shown by the solid line in FIG. 21 (b) is formed by smoothing the unevenness of the shoulder portion in the actual measurement value shown in (a), and the second OCV characteristic in which the curve is made into a database is prepared. Then, based on this second OCV characteristic, each element value such as R, r, and Zw is made into a database, and as a result, the degree of change in the element value is suppressed, and it is possible to reduce the data amount when making the database. I am trying.

Further, the battery pack database 4 stores data capable of discriminating the difference between pack states such as the configuration of the unit cells in the serial or parallel state or temperature parameters. Then, various data as the battery pack are derived or calculated from the estimation database 2 including the database of the unit cells and the battery pack.

Therefore, in step ST1 of FIG.
After performing a predetermined initial setting based on the above-mentioned initial value,
The battery capacity detection process starts from step ST2.

In step ST2 of FIG. 17, it is determined whether or not the secondary battery 12 is at rest, and if it is not at rest, it is further determined at step ST6 whether or not the secondary battery is left at rest.
In step ST4, whether it is being discharged or not,
Further, in step ST5, it is determined whether or not the battery protection unit 14 is operating, and each processing operation shown in FIG. 18 is performed based on each determination result.

If the determination in step ST2 is pause, it is determined in step ST21 whether 30 minutes, 2 hours, 4 hours or 8 hours have elapsed since the start of the pause state. Each time it is performed, the OCV detection process shown in FIG. However, step S in FIG.
When it is determined that 24 hours or more have passed at T6, it is determined that the vehicle is being left unattended. For example, every time when it is determined that 24 hours have passed in step 61, the process proceeds to step 62, and the remaining amount correction process in the unattended operation is performed. .

The OCV detection process shown in FIG.
In step ST22, the terminal voltage of the secondary battery 12 is measured. Further, in step ST23, it is determined whether or not the measured terminal voltage is after the second point, and if it is after the second point, the process proceeds to step ST24 and the OC shown in FIG.
A V estimation operation is performed, but if not, the measured terminal voltage is saved and returned.

The remaining amount correction process during standing, which is performed in step ST62 of FIG. 17, is carried out every time a predetermined long time such as 24 hours elapses. At this stage, the OCV Since the value is also stable, the OCV is not measured but the current charging rate is determined based on the measured value and the first OCV characteristic, and the detected OCV changes. Correct the full charge capacity accordingly.

Here, when left for a long time, FIG.
As illustrated in (a), for example, when the charging rate is 50% or less, almost no decrease in the full charge capacity is observed regardless of the battery temperature Tc, but when the battery temperature Tc exceeds 30 ° C., As shown in FIG. 22 (b) or (c), the decrease in full charge capacity tends to increase as the charging rate during standing increases.

Therefore, based on the relationship shown in FIG. 22, a correction amount correction database showing the change in the full charge capacity with respect to the change in the charge rate with respect to the temperature and the passage of time is created in advance and stored for each charge rate of 10%. Keep it. Then, as described above, the OCV is measured to obtain the charging rate, and at the same time, the average standing temperature is detected, the reduction amount of the full charge capacity is estimated using the correction database, and necessary correction is performed.

Further, the full charge capacity can be corrected more accurately by measuring the values of the solution resistance R and the charge transfer resistance r simultaneously with the measurement of the charge rate, but the change of the charge rate exceeds a certain value. It is preferable to perform the measurement only in such a case because the power consumption of the battery is suppressed.

Next, when it is determined in step ST3 of FIG. 17 that discharging is in progress, the process proceeds to the discharging process of FIG. 18 (b). In this discharge treatment step, the discharge current value is measured in step ST31, the ambient temperature of the secondary battery 12 is measured in step ST32, and the element value shown in FIG. 9 is corrected using the measured value. Accordingly, the discharge characteristic illustrated in FIG. 7 is calculated in step ST33, and the calculated discharge characteristic is used in step S33.
The remaining time is estimated at T34.

In addition, the current charging rate is calculated by integrating the charging rate calculated from the measured discharge current with the previously calculated charging rate in step ST35 to calculate the current charging rate.
Then, the process proceeds to next step ST36.

In step ST36, it is determined whether or not the battery voltage is lower than a preset minimum voltage, and if it is determined that the battery voltage is lower than the preset minimum voltage, a signal is sent to the battery protection unit 14 in step ST37 to turn on the switching unit 24. Processing for forcibly turning off and ending the discharge is performed.

The above estimation of the remaining capacity is based on the assumption of discharging with constant power. However,
In the case of applying to a device where surge current often flows, a mechanism that prevents the device from shutting down even if a surge current flows is necessary.

Therefore, in the case where the surge current is detected or the surge current is predicted in advance, FIG.
23, the voltage drop calculated by multiplying the internal resistance and circuit resistance of the battery by the surge current, as indicated by the dashed line in FIG. 23, against the discharge characteristics at constant power in which only the internal resistance and polarization are taken into consideration. Calculate the discharge characteristics in anticipation, and the discharge characteristics due to the surge are the shutdown voltage V
By estimating the remaining time until the time when it falls below t, the remaining amount is estimated with a margin. The effect of the surge is greater when the battery deteriorates, and is an effective means.

Not only when the voltage actually drops significantly like a surge current, but especially when it is necessary to avoid the occurrence of a shortage of the battery level during operation as much as possible, It is also possible to reserve a part of the remaining amount as insurance in advance assuming that, and notify the remaining amount by the above-mentioned remaining amount estimation.

Further, in the above-described embodiment, the final voltage Vt is set and the time until the voltage drops below the voltage Vt is notified as the remaining time. It is also possible to set the maximum current to flow to the battery and the maximum temperature that can be raised in advance by using the battery temperature estimation function, and set the time when the estimated current or battery temperature exceeds the set value as the device termination condition. It is possible.

Furthermore, step ST in FIG.
At 38, it is determined whether or not the discharge is completed. If the discharge is completed, the solution resistance R and the charge transfer resistance r in the element value of the secondary battery 12 are determined by using the method and the load circuit 38 shown in FIG. Is individually measured in step 39 and the value is stored, and the learning processing operation is performed in step 40.

The learning processing operation stores the solution resistance R, the charge transfer resistance r, and the diffusion resistance Zw measured or calculated as described above together with the charging rate, while correcting the current dependency, the temperature coefficient and the charging rate. Is corrected and the comparison processing is performed with the same numerical value stored in the past.

If the compared numerical value is within a certain range, the new numerical value is used instead of the past numerical value, but if it is out of the range, the value is saved without being used. Only keep it.

When it is determined that the value measured the next time is within a certain range from the previous time, the values of the previous time and the current time are averaged and used, and the data after the last time before and after are used. save.

On the contrary, if the next measured value is also out of the range, it is judged that the deterioration has rapidly progressed in the high temperature state, the value is used, and the data before the last two times are discarded. .

[0207] In the case where a drive current flows in a pulsed manner by operating intermittently, such as a mobile phone, which is minute even during standby, the discharge current value may be accurately measured.
It is difficult to measure V either. In this case, the voltage when the current is off is intermittently detected, and
In Fig. 4, the envelope curve indicated by the broken line is obtained, and by utilizing the fact that the envelope curve gradually approaches the OCV while decreasing, the final reaching voltage when the current is assumed to be off is estimated, and as a result, the OCV is estimated. It is possible.

Next, when it is determined in step ST4 of FIG. 17 that the battery is being charged, the charging processing step shown in FIG. 18C is started. In this step, step ST41
In step ST4, the charging current is measured at
Moving to 2, the charging rate is calculated.

In step ST42, the current charging rate is calculated by integrating the charging rate calculated last time with the charging rate calculated last time, and the current charging rate is calculated. After the transfer resistance Zw is measured, the measured value is stored together with the charging rate at that time.

When the charging is performed by the pulse power source and the above voltage and current are measured by sampling in a predetermined cycle, the gap between the pulses during charging is continuously sampled, and the measurement cannot be performed. there is a possibility. Therefore, in the case where such a condition is determined, it is possible to reduce the omission of measurement by shifting the phase at the time of voltage / current measurement by a predetermined amount, for example, every second, and taking an average value. .

Further, when the operation of the battery protection unit 14 is detected in step ST5 of FIG. 17, the charging rate calculated or measured as described above is corrected corresponding to the value corresponding to the detected content. .

FIG. 19A shows a circuit configuration for measuring the charge transfer resistance r described above by a frequency response method, in which an AC signal is sent from the measurement control means 48 to the transistor switch 52 via the operational amplifier 50. This makes it possible to apply current modulation to the load 54. Then, while changing the modulation frequency, the current and the voltage are measured by the voltage detection means and the current detection means shown in FIG. 8A, and the relationship between the modulation amplitude and the phase of both is shown in FIG.
By plotting the complex impedance as in (b), the values of the solution resistance R and the charge transfer resistance r can be individually measured from the value of the intersection with the real part.

As the secondary battery 12 deteriorates, its equivalent circuit may change from FIG. 4 (a) to FIG. 20 (a). In such a case, as shown in FIG.
When the element value is measured using the method described above, the result of plotting the complex impedance is as shown in FIG. 20 (b). As a result, the component of r2 increased by deterioration can be detected separately, and the degree of deterioration is more concrete. It can be determined

Regarding the method of measuring the internal resistance of the secondary battery 12, the switching unit 2 provided in the battery protection unit 14 is further described.
4 can be used, and the measurement can be performed by stopping the power supply to the electric device 18 at an appropriate time such as during discharging. That is,
The voltage response curve immediately after the stop of energization has a shape similar to that of FIG. 8C, and the transient resistance characteristic allows the solution resistance R and the charge transfer resistance r to be detected separately.

Although the method for separating and detecting the internal resistance has been described above, it goes without saying that it is not always necessary to separate and detect the internal resistance as described above. To collectively evaluate the internal resistance as the DC resistance component is to redefine the discharge characteristic as the OCV characteristic minus the voltage drop due to the internal resistance and the voltage drop due to the polarization. Therefore, since it is clear that the configurations described so far can be applied as they are, detailed description thereof will be omitted.

Further, when measuring the internal resistance, in order to simplify the explanation, it is assumed that each resistance is estimated by observing its response as a constant current load.
It goes without saying that a constant resistance load may be used.

In the present invention, it is essential to measure the battery parameter and use it for the next capacity estimation, and it is appropriate to separately measure the resistance component from the change in voltage and current that changes due to load fluctuation. Since it is easy for a trader, detailed description is omitted.

Furthermore, the load fluctuation is not limited to the constant current load or the resistance load, but can be observed by the load fluctuation of the connected equipment.
It is also possible to observe the battery parameter from the result. In this case, assuming that the time difference for measuring the solution resistance R is τR, the respective differences in voltage and current between two points having the time difference τR, ΔVR and ΔIR, are detected, and R = ΔVR / ΔI
It is obtained as R. In this case, if τR is too short, some τR are defined, and the convergence value (for example, the value estimated as the original time difference τR) in the plot of R and time τR in each case is detected. The solution resistance R can be obtained. Similarly, the time difference for measuring the charge transfer resistance r is τr, and it is determined from the voltage and current fluctuations during that time. Further, when a sharp current change cannot be expected, it goes without saying that the solution characteristics R and the charge transfer resistance r may be collectively measured as a direct current resistance component to estimate the discharge characteristics.

Further, the full charge capacity is obtained by dividing the charge amount obtained by integrating the charge current supplied to the secondary battery during charging and the difference between the charge rates before and after charging. However, as described above, the discharge amount obtained by integrating the discharge current during discharging can be obtained by dividing the discharge amount by the difference between the charging rates before and after discharging.

In this case, the full charge capacity detected by discharging and the full charge capacity detected by charging are usually almost the same, but they are different when experiencing high temperature storage deterioration. Therefore, it is possible to detect high temperature leaving etc. by measuring the ambient environment condition at a constant period with a clock circuit etc. inside the microcomputer while it is left unattended, but in addition, the full charge capacity detected by discharging and the full charge capacity detected by charging When it is detected that the difference is large, it is confirmed that the deterioration has progressed all at once due to being left at a high temperature or the like, so that it is possible to reliably notify or display the connected device.

At the start of discharge, the discharge characteristic is estimated to estimate the remaining time, and then the remaining time is changed while detecting the change in the charging rate by current integration. The estimated change in discharge voltage may differ from the estimated change in discharge voltage.

In such a case, it is preferable to match the remaining time estimation value estimated by integration with the remaining time estimation value due to the actual change of the discharge voltage. Therefore, if the change in battery voltage is monitored and the estimated discharge characteristics are different,
The estimated value and the measured value are combined by changing the charging rate used to estimate the remaining time so that the value indicated by the estimated discharge characteristics approaches the measured value, and the accuracy of the estimated remaining time value is improved. It goes without saying that you may improve it.

Furthermore, when the measured battery voltage changes so as to rapidly approach the cutoff voltage, the cutoff voltage is approaching. It goes without saying that communication may be sent.

Although it has been described above that a temperature transition database may be created by actual measurement and the temperature dependency may be taken into consideration, the temperature dependency is calculated by using the equivalent circuit of FIG. The size of the database can be reduced by calculation. The calculation method is as described above.

Although the method of estimating the remaining battery level has been described above, it goes without saying that this estimating means need not be provided on the battery pack side. In that case, for example, the estimation process itself can be removed from the battery pack side by incorporating the remaining amount estimation process into the control means on the device side in which the battery pack is mounted. In that case, in order to reduce costs and improve the speed of estimation processing, it is desirable to put most of the databases required for estimation processing on the device side together with the estimation processing means.

Specifically, the database 6 of the unit cells constituting the battery pack is placed on the electric device 18 side, and the database 4 of the battery pack in which the amount of the database itself is not large and the database for correcting the database of the unit battery are the battery packs. When the battery pack 16 and the electric device 18 using the battery pack 16 are connected to each other by placing the battery pack 16 on the 16 side, a necessary database is taken into the electric device 18 side by the communication means between the battery pack 16 and the electric device 18 to obtain the estimation. It is possible to equip the device side with a different database 2. It goes without saying that such a configuration makes it possible to cope with changes in the unit cell itself and changes in the configuration of the battery pack.

Further, it has been described that the internal resistance of the unit cell is measured and the database is corrected. However, including the measuring means, the means for detecting the battery voltage, the current and the like are left on the side of the battery pack, and the integrated current value is set. Needless to say, the remaining amount estimation method described above can be directly realized by measuring the internal resistance measurement value and the like in the battery pack and transmitting it to the device side.

Further, in the above embodiment, the battery capacity detecting device 1
An example has been shown in which the driving power is supplied from the secondary battery 12 in the battery pack 16 even when a part or all of 0s are integrally housed in the battery pack 16. However, FIG.
As illustrated in FIG. 5, a dedicated power source 60 for driving an electronic circuit including a small secondary battery or a capacitor is provided in the battery pack 16 at the same time, and the dedicated power source 60 allows the battery capacity detection device 1
By driving the circuit of 0, the influence of the current consumption on the secondary battery whose remaining amount should be detected can be prevented, and the OCV and the remaining battery amount can be accurately measured.

When the voltage value of the dedicated power source 60 is constantly detected by the voltage monitoring means 61 and the voltage determining means 62 determines that the value is below the set value, the switch control means 63 turns on the switch 64. The secondary battery 12 is switched to charge the dedicated power source 60. Then, when the charging is completed, the charge amount detecting means 65 detects the charge amount during that time, and the battery charge calculating means 9 subtracts the detected charge amount from the current remaining charge in the secondary battery 12 to obtain the remaining charge. Correction is performed. In this case, if the charge amount for the dedicated power source 60 is constant, this constant amount may be stored in advance, and the constant amount may be subtracted without detecting the charge amount each time the dedicated power source 60 is fully charged. It is possible.

[0230] Furthermore, A / provided in the battery pack 16
The D converter can be calibrated by an instruction from the electric device 18 side to which the battery pack 16 is attached. In this, a subroutine for calibration is installed in advance in the software of the battery capacity detection device 10 provided in the battery pack 16, and the subroutine is executed by an instruction from the electric device 18 side.

The specific processing procedure is as follows:
Side sends a command to perform A / D conversion to the battery pack 16 side, and the electric device 18 reads the converted A / D conversion value and determines whether or not the value is optimum. If it is not the optimum value, the calibration value is set to the battery pack 16
It is sent to the side, the A / D converted value is read again, and the process is repeated until the optimum value is determined.

Cost can be reduced by automating the above-described calibration operation at the time of initial assembly. Also, by writing this calibrated optimum value in an electrically erasable non-volatile memory, it is possible to respond to changes over time after assembly, and
It is preferable because it can respond to a reset start by system reset.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an example in which the present invention is applied to a battery pack.

FIG. 2 is a graph showing an example of an open circuit voltage characteristic of a secondary battery, in which (a) shows a relationship between a charging rate and an open circuit voltage,
(B) shows the process of determining the charging rate using the open circuit voltage characteristic.

FIG. 3 is a graph showing changes in battery voltage and charging current during charging of a secondary battery.

FIG. 4 is an explanatory diagram showing an equivalent circuit of a secondary battery and a situation of frequency response.

FIG. 5 is an explanatory diagram showing a process of estimating an open circuit voltage.

FIG. 6 is a graph showing the relationship between open circuit voltage characteristics and battery voltage characteristics.

FIG. 7 is a graph showing an example of discharge characteristics of a secondary battery, in which (a) shows changes in the graph due to differences in load current,
(B) shows the change of the graph accompanying the deterioration of the battery, and (c) shows the change of the graph accompanying the change of the ambient temperature.

FIG. 8 is an explanatory diagram showing a process of detecting the internal resistance of the secondary battery, in which (a) shows a circuit configuration for measuring the internal resistance of the battery and (b) shows a change in current supplied to a load. To
(C) shows changes in terminal voltage.

FIG. 9 is a graph showing the relationship between each element value forming the equivalent circuit of the secondary battery and the charging rate.

FIG. 10 is a graph showing an example of the temperature dependence of the element value of the secondary battery.

FIG. 11 is an equivalent circuit of a battery pack considering the temperature dependence of the battery.

12 is a discharge characteristic diagram illustrating a method of obtaining discharge characteristics based on the equivalent circuit of FIG.

13 is a flowchart illustrating a main process for obtaining the discharge characteristic diagram of FIG.

14 is a flowchart illustrating a first process for obtaining the discharge characteristic diagram of FIG.

FIG. 15 is a flowchart illustrating a second process for obtaining the discharge characteristic diagram of FIG.

FIG. 16 is a block diagram showing an example in which the present invention is applied to a battery pack.

FIG. 17 is an overall flowchart showing a capacity detection procedure performed by the control unit.

FIG. 18 is a flowchart showing a control procedure in each operation mode.

FIG. 19 is an explanatory diagram showing another step of detecting the internal resistance of the secondary battery, where (a) is a circuit configuration for measuring the internal resistance of the battery and (b) is a plot result of complex impedance. Are shown respectively.

20A and 20B are explanatory diagrams when the secondary battery is deteriorated, in which FIG. 20A shows an equivalent circuit in that case, and FIG. 20B shows a plot result of complex impedance.

FIG. 21 is a graph illustrating a first OCV characteristic and a second OCV characteristic.

FIG. 22 is a graph exemplifying the relationship between the battery temperature and the correction amount of the full charge capacity over time with the charging rate as a parameter.

FIG. 23 is a graph showing discharge characteristics when a surge current flows.

FIG. 24 is an explanatory diagram showing an OCV estimation procedure in the case where a current intermittently flows in a battery even during standby.

FIG. 25 is an electric circuit diagram showing another embodiment of the battery capacity detecting device.

[Explanation of symbols]

2 estimation database 4 Battery pack database 6 cell database 7 Discharge characteristics estimation means 8 Charge / discharge amount detection means 9 Battery level calculator 10 Battery capacity detector 12 secondary battery 14 Battery protection part 16 battery pack 18 electrical equipment 20 communication circuits 22 FET 24 Switching unit 26 Protection circuit 28 External circuit group 30 control unit 32 Temperature detection circuit 34 Voltage detection circuit 36 Current detection circuit 38 Load circuit 40 Temperature detection means 42 switching transistor 44 Resistance for current detection 46 load resistance 48 measurement control means 50 operational amplifier 52 transistor switch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akiyoshi Nishijima             Hitachi Ma, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. (72) Inventor Yoichi Hashimoto             Hitachi Ma, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. F term (reference) 2G016 CB05 CB06 CB11 CB12 CB21                       CB22 CB25 CB31 CB32 CC01                       CC02 CC03 CC04 CC05 CC06                       CC07 CC09 CC12 CC13 CC16                       CC23 CC24 CC26 CC27 CC28                       CD02 CD04 CD06 CF06                 5H030 AA01 AS06 FF22 FF41

Claims (15)

[Claims] 1. For a secondary battery whose battery capacity is to be detected,
The open circuit voltage characteristics indicating the relationship between the charging rate and the open circuit voltage are measured in advance and stored in a database, while the element values that are equivalently present inside the secondary battery are stored in a database, and the databased element values and From the discharge power or discharge current value as the discharge condition of the battery and the charging rate estimated from the open circuit voltage, the discharge characteristic of the secondary battery is calculated using the open circuit voltage, and the battery voltage reaches the end voltage. In the battery capacity detection method of estimating the remaining time or the remaining capacity until the charging rate is detected, the first open circuit voltage characteristic in which the measured value is faithfully stored in a database is used. A method for detecting battery capacity, characterized in that the discharge characteristic is calculated by utilizing a second open circuit voltage characteristic which is a smooth approximation of the first open circuit voltage characteristic and is made into a database. Law. 2. A secondary battery whose battery capacity is to be detected,
The open circuit voltage characteristics that show the relationship between the charging rate and the open circuit voltage are measured in advance, and the measured values are stored in a database, while the open circuit voltage of the secondary battery is measured, and the open circuit voltage obtained by the measurement and the above It is a battery capacity detection method that estimates the charging rate at the time of measurement from the database, and it is determined that the open circuit voltage measurement process has been entered during the period when the load current is intermittently supplied from the secondary battery. And a method for detecting a battery capacity, wherein an envelope curve of voltage change during a period in which no current flows is obtained, and an open circuit voltage is estimated from a converged value of the envelope curve. 3. A secondary battery whose battery capacity is to be detected,
The open circuit voltage characteristics that show the relationship between the charging rate and the open circuit voltage are measured in advance, and the measured values are stored in a database, while the open circuit voltage of the secondary battery is measured, and the open circuit voltage obtained by the measurement and the above This is a battery capacity detection method that estimates the charging rate at the time of measurement from the database.For each charging rate, the relationship between the battery temperature and the rate of decrease in full charge capacity is provided in advance as a database for correction, and the load from the secondary battery When it is determined that the current supply has been substantially stopped, the charging rate is estimated from the measured voltage value and open circuit voltage characteristic, while the charging rate, battery temperature, and charging rate A method for detecting battery capacity, comprising performing correction processing of full charge capacity from the change using the correction database. 4. For a secondary battery whose battery capacity is to be detected,
The open circuit voltage characteristics indicating the relationship between the charging rate and the open circuit voltage are measured in advance and stored in a database, while the element values that are equivalently present inside the secondary battery are stored in a database, and the databased element values and From the value of the discharge current at the start of discharge and the charging rate estimated from the open circuit voltage, the discharge characteristic of the secondary battery is further calculated using the open circuit voltage, and the remaining time until the battery voltage reaches the final voltage or In a battery capacity detection method that estimates the remaining capacity, if it is determined or assumed that the current flowing through the secondary battery contains a surge current, the discharge characteristics that take the surge current into consideration are estimated, and the discharge characteristics are estimated. A method for detecting battery capacity, characterized in that the remaining time is calculated based on. 5. A battery capacity which comprises a secondary battery in which one or more unit cells are combined in a case to form a battery pack, and which can detect the remaining capacity of a battery pack detachably attached to an electric device. In the detection device, the secondary battery charging / discharging data and data processing means are provided, and the current remaining capacity of the battery can be calculated in real time by the calculation of the data processing means. The data is separately provided in a unit cell database and a battery pack database, and the unit cell or the battery pack database can be replaced for each type of battery pack or each type of unit cell. The battery database holds the data on the unit cells, while the database of the battery pack shows the combination state of the unit cells. Holds data capable of locating the housed state to the over scan, using the data from both databases, the battery capacity detection device is characterized in that to enable derive data of the entire battery pack. 6. The database of the unit cells includes data about element values forming an equivalent circuit of the unit cells and data about open circuit voltage characteristics, and the database of the battery pack contains data about combinations of the unit cells. 6. Data including the data for correcting the element value according to the change in the capacity of the unit cell, the data regarding heat generation due to the storage state of the unit cell in the case, and the resistance value of the electronic circuit of the battery pack. The battery capacity detection device described. 7. The data regarding the open circuit voltage faithfully stores a database of measured values, and includes a first open circuit voltage characteristic used when a charge rate is detected and the first open circuit voltage characteristic. The battery capacity detection device according to claim 6, further comprising a second open circuit voltage characteristic that is smoothly approximated into a database and used when calculating a discharge characteristic. 8. A discharge characteristic estimating unit capable of estimating discharge characteristics of a battery pack by using the unit cell database and the battery pack database, and detecting a voltage value and a charging / discharging current of a secondary battery to determine a charging / discharging amount. 6. A charging / discharging amount detecting means capable of detecting a charge, a remaining battery amount calculating means capable of calculating a remaining battery amount from the estimated discharge characteristic and the detected charging / discharging amount. 8. The battery capacity detection device according to any one of 7 to 7. 9. The discharge characteristic estimating means is configured to increase the temperature inside the battery pack due to a current flowing through a resistance component constituting the secondary battery, and a current value based on the resistance component changed due to the temperature increase. 9. The battery capacity detecting device according to claim 8, wherein a discharge characteristic determined from an open circuit voltage, a resistance component, and a current value can be derived by sequentially calculating and. 10. The battery capacity detection device according to claim 9, wherein the temperature rise inside the battery pack is calculated in consideration of heat generation due to entropy change. 11. The calculation of the discharge characteristic in the discharge characteristic estimating means is performed on the assumption of a minute change in the charging rate, and it is assumed that the first current before the change in the charging rate is sustained. The second current after the change of the charging rate is calculated from the temperature rise calculated by the above, and the current value after the change of the charging rate is corrected by using the second current as one estimation step. 10. The battery capacity detection device according to claim 9, wherein the estimation step is repeated. 12. The discharge characteristic estimation means uses data representing the efficiency of the power source of the device to which the battery pack is connected as data used for estimation, and calculates the discharge characteristic including the efficiency with respect to the battery output. Claims 8 to 1
1. The battery capacity detection device according to any one of 1. 13. The battery capacity detection device according to claim 5, wherein all or part of the battery capacity is integrally housed in a battery pack. 14. The battery capacity detecting device according to claim 13, wherein at least the data processing means is accommodated in the electric equipment side, and the rest is accommodated in the battery pack side. 15. The battery capacity detection device according to claim 14, wherein all of them are integrally housed in a battery pack, and a power supply dedicated to battery capacity detection is provided separately from the battery whose remaining capacity is to be measured. .