JP6801613B2 - Battery pack - Google Patents

Description

The present invention relates to a battery pack.

As an existing battery pack, there is a battery pack that estimates the battery charge rate (SOC (State Of Charge)) from the open circuit voltage of the battery after the battery has been discharged or charged.
As related techniques, for example, there are Patent Documents 1 to 6.

International Publication No. 2013/0544414 International Publication No. 2012/066643 JP-A-2015-227840 Japanese Unexamined Patent Publication No. 2011-257219 Japanese Unexamined Patent Publication No. 2005-130559 JP-A-2002-268818

However, the open circuit voltage of the battery acquired after the end of discharge or the end of charging of the battery is affected by the polarization of the battery and may not be an accurate value. Therefore, in the above-mentioned battery pack, the estimation accuracy of the battery charge rate may be low.

Therefore, an object of one aspect of the present invention is to provide a battery pack capable of accurately estimating the open circuit voltage of the battery after the polarization is eliminated after the battery has been discharged or charged.

A battery pack according to one embodiment of the present invention includes a battery, a voltage detection unit that detects the voltage of the battery, and an estimation unit.
The estimation unit is a first voltage or pause detected by the voltage detection unit after the lapse of the first predetermined time from the start of the pause period in the pause period after the end of the battery discharge and before the polarization of the battery is eliminated. The ratio of the first voltage to the second voltage and the coefficient were multiplied by the second voltage detected by the voltage detector after the lapse of the second predetermined time longer than the first predetermined time from the start of the period. The result of adding the values is estimated as the open circuit voltage after the polarization of the battery is eliminated.

Further, the estimation unit is a first voltage detected by the voltage detection unit after the lapse of the first predetermined time from the start of the pause period in the pause period after the charging of the battery is completed and before the polarization of the battery is eliminated. Alternatively, the ratio and coefficient of the first voltage and the second voltage are calculated from the second voltage detected by the voltage detector after the lapse of the second predetermined time longer than the first predetermined time from the start of the pause period. The result of subtracting the multiplied value is estimated as the open circuit voltage after the polarization of the battery is eliminated.

According to the present invention, it is possible to accurately estimate the open circuit voltage of the battery after the polarization is eliminated after the battery has been discharged or charged.

It is a figure which shows an example of the battery pack of an embodiment. It is a figure which shows an example of the voltage of the battery after the end of discharge or the end of charge. It is a figure which shows an example of the information which shows the correspondence relationship between the charge rate of a battery, and an open circuit voltage. It is a flowchart which shows an example of the charge rate estimation process. It is a flowchart which shows an example of an open circuit voltage estimation process. It is a flowchart which shows an example of the open circuit voltage estimation process in the modification 1. It is a flowchart which shows an example of the open circuit voltage estimation processing in the modification 2. It is a flowchart which shows an example of the open circuit voltage estimation processing in the modification 3. It is a flowchart which shows an example of the open circuit voltage estimation processing in the modification 4. It is a flowchart which shows an example of the charge rate estimation process in the modification 5. It is a flowchart which shows one other example of the open circuit voltage estimation processing in the modification 6. It is a flowchart which shows another example of the open circuit voltage estimation processing in the modification 7.

Hereinafter, embodiments will be described in detail based on the drawings.
FIG. 1 is a diagram showing an example of a battery pack of the embodiment.
The battery pack shown in FIG. 1 includes a battery B, a current detection unit 1, a voltage detection unit 2, a temperature detection unit 3, a storage unit 4, and an estimation unit 5. The battery pack shall be mounted on a vehicle such as a hybrid vehicle, a plug-in hybrid vehicle, or an electric vehicle.

The battery B is composed of one or more secondary batteries such as a lithium ion battery and a nickel hydrogen battery, for example. The battery B is charged when power is supplied from the charger Ch to the battery B, or when regenerative power is supplied to the battery B from a load Lo such as a traveling motor. Further, when power is supplied from the battery B to the load Lo, the battery B is discharged.

Here, the change in the voltage of the battery B after the end of discharging or the end of charging will be described with reference to FIG.
FIG. 2A is a diagram showing a change in the voltage of the battery B after the end of discharging. The vertical axis of the graph shown in FIG. 2A shows the voltage of the battery B, and the horizontal axis shows the time. Further, FIG. 2B is a diagram showing a change in the voltage of the battery B after the end of charging. The vertical axis of the graph shown in FIG. 2B shows the voltage of the battery B, and the horizontal axis shows the time.

In the graph shown in FIG. 2A, a third predetermined time (from the start time t0 of the pause period in which the battery B is neither charged nor discharged to the time t3 when the polarization of the battery B is eliminated after the discharge is completed ( After the end of discharge and before the polarization of the battery B is eliminated), the voltage of the battery B rises due to the influence of the polarization according to the discharge of the battery B before the start of the pause period. ing.

In the graph shown in FIG. 2B, a third predetermined time (from the start time t0 of the pause period in which the battery B is not charged or discharged to the time t3 when the polarization of the battery B is eliminated after the charging is completed ( After the end of charging and before the polarization of the battery B is eliminated), the voltage of the battery B drops due to the influence of the polarization according to the charging of the battery B before the start of the pause period). ing.

The current detection unit 1 shown in FIG. 1 is composed of, for example, a shunt resistor or a Hall element, and detects the current I flowing through the battery B.
The voltage detection unit 2 is composed of, for example, an IC (Integrated Circuit) and detects the voltage V of the battery B.

The temperature detection unit 3 is composed of, for example, a thermistor, and detects the temperature T of the battery B.
The storage unit 4 is composed of, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory). Further, the storage unit 4 stores information indicating the correspondence between the charge rate of the battery B and the open circuit voltage of the battery B, and the coefficients a and b used when estimating the open circuit voltage of the battery B after the polarization is eliminated. I remember.

Here, information indicating the correspondence relationship between the charge rate of the battery B and the open circuit voltage of the battery B will be described.
FIG. 3 is a diagram showing an example of information showing a correspondence relationship between the charge rate of the battery B and the open circuit voltage. The vertical axis of the graph shown in FIG. 3 shows the open circuit voltage of the battery B, and the horizontal axis shows the charge rate of the battery B.

The curve of the graph shown in FIG. 3 shows information indicating the correspondence between the charge rate of the battery B and the open circuit voltage, and by referring to this information, the charge rate of the battery B can be uniquely calculated from the open circuit voltage of the battery B. Can be sought.

The estimation unit 5 shown in FIG. 1 is composed of, for example, a CPU (Central Processing Unit), a multi-core CPU, or a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), or the like).

After determining that the pause period shown in FIG. 2 (a) or FIG. 2 (b) has started, the estimation unit 5 pauses when the absolute value of the current I detected by the current detection unit 1 becomes equal to or greater than the current threshold value Is. Judge that the period has expired.

Further, after determining that the pause period has ended, the estimation unit 5 determines that the pause period has started when the absolute value of the current I detected by the current detection unit 1 becomes less than the current threshold value Is.
Further, the estimation unit 5 executes the charge rate estimation process when it determines that the pause period has started.

FIG. 4 is a flowchart showing an example of the charge rate estimation process.
First, if the estimation unit 5 determines that the first predetermined time has elapsed from the start of the pause period before the end of the pause period (S101: No, S102: Yes), the estimation unit 5 acquires the first voltage OCV1 (S103). ). For example, the estimation unit 5 determines the voltage V detected by the voltage detection unit 2 at the time t1 after the lapse of the first predetermined time from the start time t0 of the rest period shown in FIG. 2 (a) or FIG. 2 (b). Acquired as the first voltage OCV1.

Next, when the estimation unit 5 determines that a second predetermined time longer than the first predetermined time has elapsed from the start of the pause period before the end of the pause period (S104: No, S105: Yes), the first The voltage OCV2 of 2 is acquired (S106). For example, the estimation unit 5 determines the voltage V detected by the voltage detection unit 2 at the time t2 after the lapse of the second predetermined time from the start time t0 of the rest period shown in FIG. 2 (a) or FIG. 2 (b). Acquired as the second voltage OCV2.

Next, the estimation unit 5 executes the open circuit voltage estimation process using the first voltage OCV1, the second voltage OCV2, and the coefficients a and b, so that the open circuit voltage of the battery B after polarization elimination is executed. Is estimated (S107).

Next, the estimation unit 5 estimates the charge rate of the battery B using the estimated open circuit voltage (S108). For example, the estimation unit 5 refers to the information shown in FIG. 3 and sets the charge rate corresponding to the estimated open circuit voltage as the charge rate of the battery B.

Next, when the estimation unit 5 determines that the polarization of the battery B has been eliminated before the end of the rest period (S109: No, S110: Yes), the estimation unit 5 acquires the third voltage OCV3 (S111), and the third voltage OCV3 is acquired. Using the voltage OCV3 of 3, the coefficients a and b are updated (S112), and the current charge rate estimation process is completed. For example, the estimation unit 5 determines that the polarization of the battery B has been eliminated when a third predetermined time elapses from the start time t0 of the rest period shown in FIG. 2A or FIG. 2B. Further, for example, the estimation unit 5 has a voltage V detected by the voltage detection unit 2 at a time t3 after the lapse of a third predetermined time from the start time t0 of the rest period shown in FIG. 2 (a) or FIG. 2 (b). Is acquired as the third voltage OCV3.

When the estimation unit 5 determines that the rest period has ended (S101: Yes, S104: Yes, S109: Yes), the estimation unit 5 ends the current charge rate estimation process.
FIG. 5 is a flowchart showing an example of the open circuit voltage estimation process.

When the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is rising (that is, after the end of discharge) during the pause period (S11: Yes), the ratio r and the coefficient a are obtained (S12). , The ratio r and the coefficient a are multiplied (S13), and the result of adding the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a is the result of the battery B after polarization elimination. The open circuit voltage is used (S14). After that, the case where the voltage of the battery B rises during the pause period can be read as the case after the end of discharge.

On the other hand, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (that is, after the end of charging) during the pause period (S11: No), the ratio r and the coefficient b are obtained ( S15), the ratio r and the coefficient b are multiplied (S16), and the result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 is obtained from the battery after polarization elimination. Let the open circuit voltage of B be (S17). After that, the case where the voltage of the battery B drops during the rest period can be read as the case after the end of charging.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (1)>
In the current charge rate estimation process when the voltage of the battery B rises during the pause period, the estimation unit 5 calculates the ratio r1 = the second voltage OCV2 / the first voltage OCV1 and the coefficient a11 from the storage unit 4. The ratio r1 as the ratio r and the coefficient a11 as the coefficient a are obtained by reading out, and the result of calculating the voltage = first voltage OCV1 + ratio r1 × coefficient a11 is the open circuit voltage of the battery B after polarization elimination. Estimate as.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B rises during the pause period (when the polarization of the battery B is eliminated), the coefficient a11 = (Third voltage OCV3-first voltage OCV1) / The result of calculating the ratio r1 is stored as a coefficient a11 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the rest period rises. To memorize.

As a result, when the first voltage OCV1 and the ratio r1 acquired in the next and subsequent charge rate estimation processes when the voltage of the battery B during the pause period rises, the voltage of the battery B during the pause period rises. When the value is the same as or substantially the same as the first voltage OCV1 and the ratio r1 acquired in the current charge rate estimation process, and when the voltage increase of the battery B due to polarization is constant or substantially constant. By using the coefficient a11 in the next and subsequent charge rate estimation processes when the voltage of the battery B rises during the pause period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (Part 2)>
The estimation unit 5 calculates the ratio r2 = the first voltage OCV1 / the second voltage OCV2 and the coefficient a12 from the storage unit 4 in the current charge rate estimation process when the voltage of the battery B rises during the pause period. The ratio r2 as the ratio r and the coefficient a12 as the coefficient a are obtained by reading out, and the result of calculating the voltage = first voltage OCV1 + ratio r2 × coefficient a12 is the open circuit voltage of the battery B after polarization elimination. Estimate as.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B rises during the pause period, the coefficient a12 = (third voltage OCV3-th). The result of calculating the voltage OCV1) / ratio r2 of 1 is stored in the storage unit 4 as a coefficient a12 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the rest period rises.

As a result, when the first voltage OCV1 and the ratio r2 acquired in the next and subsequent charge rate estimation processes when the voltage of the battery B during the pause period rises, the voltage of the battery B during the pause period rises. When the value is the same as or substantially the same as the first voltage OCV1 and the ratio r2 acquired in the current charge rate estimation process, and the amount of increase in the voltage of the battery B due to polarization is constant or substantially constant. By using the coefficient a12 in the next and subsequent charge rate estimation processes when the voltage of the battery B rises during the rest period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (Part 3)>
In the current charge rate estimation process when the voltage of the battery B rises during the pause period, the estimation unit 5 calculates the ratio r1 = the second voltage OCV2 / the first voltage OCV1 and the coefficient a21 from the storage unit 4. The ratio r1 as the ratio r and the coefficient a21 as the coefficient a are obtained by reading out, and the result of calculating the voltage = second voltage OCV2 + ratio r1 × coefficient a21 is the open circuit voltage of the battery B after polarization elimination. Estimate as.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B rises during the pause period, the coefficient a21 = (third voltage OCV3-th). The result of calculating the voltage OCV2) / ratio r1 of 2 is stored in the storage unit 4 as a coefficient a21 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the pause period rises.

As a result, when the voltage of the battery B during the hibernation period rises, the second voltage OCV2 and the ratio r1 acquired in the next and subsequent charge rate estimation processes increase, when the voltage of the battery B during the hibernation period rises. When the second voltage OCV2 and the ratio r1 acquired in the current charge rate estimation process have the same value or substantially the same value, and the voltage increase of the battery B due to polarization is constant or substantially constant. By using the coefficient a21 in the next and subsequent charge rate estimation processes when the voltage of the battery B rises during the rest period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (4)>
The estimation unit 5 calculates the ratio r2 = the first voltage OCV1 / the second voltage OCV2 and the coefficient a22 from the storage unit 4 in the current charge rate estimation process when the voltage of the battery B rises during the pause period. The ratio r2 as the ratio r and the coefficient a22 as the coefficient a are obtained by reading out, and the result of calculating the voltage = second voltage OCV2 + ratio r2 × coefficient a22 is the open circuit voltage of the battery B after polarization elimination. Estimate as.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B rises during the pause period, the coefficient a22 = (third voltage OCV3-th). The result of calculating the voltage OCV2) / ratio r2 of 2 is stored in the storage unit 4 as a coefficient a22 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the pause period rises.

As a result, when the second voltage OCV2 and the ratio r2 acquired in the next and subsequent charge rate estimation processes when the voltage of the battery B during the pause period rises, the voltage of the battery B during the pause period rises. When the second voltage OCV2 and the ratio r2 acquired in the current charge rate estimation process have the same value or substantially the same value, and the voltage increase of the battery B due to polarization is constant or substantially constant. By using the coefficient a22 in the next and subsequent charge rate estimation processes when the voltage of the battery B rises during the rest period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (No. 5)>
In the current charge rate estimation process when the voltage of the battery B drops during the pause period, the estimation unit 5 calculates the ratio r1 = the second voltage OCV2 / the first voltage OCV1 and the coefficient b11 from the storage unit 4. The ratio r1 as the ratio r and the coefficient b11 as the coefficient b are obtained by reading out, and the result of calculating the voltage = first voltage OCV1-ratio r1 × coefficient b11 is the result of opening the battery B after depolarization. Estimated as voltage.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B drops during the pause period, the coefficient b11 = (first voltage OCV1-first). The result of calculating the voltage OCV3) / ratio r1 of 3 is stored in the storage unit 4 as a coefficient b11 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the rest period drops.

As a result, the first voltage OCV1 and the ratio r1 acquired in the next and subsequent charge rate estimation processes when the voltage of the battery B during the pause period drops will be the case where the voltage of the battery B during the pause period drops. When the value is the same as or substantially the same as the first voltage OCV1 and the ratio r1 acquired in the current charge rate estimation process, and when the voltage drop width of the battery B due to polarization is constant or substantially constant. By using the coefficient b11 in the next and subsequent charge rate estimation processes when the voltage of the battery B drops during the rest period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (No. 6)>
The estimation unit 5 calculates the ratio r2 = the first voltage OCV1 / the second voltage OCV2 and the coefficient b12 from the storage unit 4 in the current charge rate estimation process when the voltage of the battery B drops during the pause period. The ratio r2 as the ratio r and the coefficient b12 as the coefficient b are obtained by reading out, and the result of calculating the voltage = first voltage OCV1-ratio r2 × coefficient b12 is the result of opening the battery B after depolarization. Estimated as voltage.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B drops during the pause period, the coefficient b12 = (first voltage OCV1-first). The result of calculating the voltage OCV3) / ratio r2 of 3 is stored in the storage unit 4 as a coefficient b12 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the rest period drops.

As a result, the first voltage OCV1 and the ratio r2 acquired in the next and subsequent charge rate estimation processes when the voltage of the battery B during the pause period drops will be the case where the voltage of the battery B during the pause period drops. When the value is the same as or substantially the same as the first voltage OCV1 and the ratio r2 acquired in the current charge rate estimation process, and the voltage drop width of the battery B due to polarization is constant or substantially constant. By using the coefficient b12 in the next and subsequent charge rate estimation processes when the voltage of the battery B drops during the rest period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (7)>
In the current charge rate estimation process when the voltage of the battery B drops during the pause period, the estimation unit 5 calculates the ratio r1 = the second voltage OCV2 / the first voltage OCV1 and also calculates the coefficient b21 from the storage unit 4. The ratio r1 as the ratio r and the coefficient b21 as the coefficient b are obtained by reading out, and the result of calculating the voltage = second voltage OCV2-ratio r1 × coefficient b21 is the result of opening the battery B after depolarization. Estimated as voltage.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B drops during the pause period, the coefficient b21 = (second voltage OCV2-th). The result of calculating the voltage OCV3) / ratio r1 of 3 is stored in the storage unit 4 as a coefficient b21 used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the rest period drops.

As a result, when the voltage of the battery B during the pause period drops, the second voltage OCV2 and the ratio r1 acquired in the next and subsequent charge rate estimation processes will be the case where the voltage of the battery B during the pause period drops. When the second voltage OCV2 and the ratio r1 acquired in the current charge rate estimation process have the same value or substantially the same value, and the voltage drop width of the battery B due to polarization is constant or substantially constant. By using the coefficient b21 in the next and subsequent charge rate estimation processes when the voltage of the battery B drops during the pause period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

<Example of estimating the open circuit voltage of battery B after elimination of polarization and example of updating the coefficient (No. 8)>
The estimation unit 5 calculates the ratio r2 = the first voltage OCV1 / the second voltage OCV2 and the coefficient b22 from the storage unit 4 in the current charge rate estimation process when the voltage of the battery B drops during the pause period. The ratio r2 as the ratio r and the coefficient b22 as the coefficient b are obtained by reading out, and the result of calculating the voltage = second voltage OCV2-ratio r2 × coefficient b22 is the result of opening the battery B after depolarization. Estimated as voltage.

Further, when the estimation unit 5 determines that the polarization of the battery B has been eliminated in the current charge rate estimation process when the voltage of the battery B drops during the pause period, the coefficient b22 = (second voltage OCV2-th). The result of calculating the voltage OCV3) / ratio r2 of 3 is stored in the storage unit 4 as a coefficient b22 to be used for the next and subsequent charge rate estimation processing when the voltage of the battery B during the rest period drops.

As a result, the second voltage OCV2 and the ratio r2 acquired in the next and subsequent charge rate estimation processes when the voltage of the battery B during the pause period drops will be the case when the voltage of the battery B during the pause period drops. When the second voltage OCV2 and the ratio r2 acquired in the current charge rate estimation process have the same value or substantially the same value, and the voltage drop width of the battery B due to polarization is constant or substantially constant. By using the coefficient b22 in the next and subsequent charge rate estimation processes when the voltage of the battery B drops during the suspension period, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the third measured value. The voltage can be approached to OCV, and the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately.

As described above, in the battery pack of the embodiment, since the open circuit voltage of the battery B after the discharge of the battery B or the charge is completed and the polarization is eliminated can be accurately estimated, the estimated open circuit voltage is used. Therefore, the charge rate of the battery B can be estimated accurately.

Further, since the battery pack of the embodiment has a configuration in which the coefficients a and b are updated by using the measured value of the open circuit voltage of the battery B after the polarization is eliminated, the battery estimated in the charge rate estimation process from the next time onward. The estimation accuracy of the open circuit voltage of B can be improved.

Further, in the battery pack of the embodiment, if it is possible to acquire the first voltage OCV1 and the second voltage OCV2 in the pause period, even if the pause period is a relatively short time, after the polarization is eliminated. The open circuit voltage of the battery B can be estimated accurately.

Further, the present invention is not limited to the above embodiments, and various improvements and changes can be made without departing from the gist of the present invention.
<Modification example 1>
FIG. 6 is a flowchart showing an example of the open circuit voltage estimation process in the first modification.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is increasing (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the ratio r is equal to or less than the threshold rth. (S21: Yes), the coefficient a is set to the first coefficient a (S22), the ratio r is multiplied by the coefficient a (S13), and the ratio r is added to the first voltage OCV1 or the second voltage OCV2. The result of adding the value obtained by multiplying the coefficient a by the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14).

On the other hand, when the estimation unit 5 determines that the ratio r is larger than the threshold rhth (S21: Yes), the coefficient a is set to the second coefficient a smaller than the first coefficient a (S23), and the ratio r and the coefficient a are set. (S13), and the result of adding the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a is taken as the open circuit voltage of the battery B after polarization elimination (S13). S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the ratio r is equal to or less than the threshold value rth. (S24: Yes), the coefficient b is set to the first coefficient b (S25), the ratio r is multiplied by the coefficient b (S16), and the ratio r is derived from the first voltage OCV1 or the second voltage OCV2. The result of subtracting the value obtained by multiplying and the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the ratio r is larger than the threshold value rth (S24: No), the coefficient b is set to the second coefficient b smaller than the first coefficient b (S26), and the ratio r and the coefficient b are set. And (S16), and the result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 is taken as the open circuit voltage of the battery B after polarization elimination (S16). S17).

The estimation unit 5 may be configured so that the coefficients a and b become larger as the ratio r becomes smaller, and the coefficients a and b become smaller as the ratio r becomes larger.
According to the open-circuit voltage estimation process shown in FIG. 6, when the ratio r is small, the coefficients a and b can be increased, and when the ratio r is large, the coefficients a and b can be decreased, so that the ratio r fluctuates. Fluctuations in the multiplication value of the ratio r and the coefficients a and b can be suppressed. As a result, even if the ratio r fluctuates due to noise contained in the voltage V detected by the voltage detection unit 2, the fluctuation of the open circuit voltage of the battery B after the polarization is eliminated can be suppressed, so that the polarization is eliminated. The open circuit voltage of the battery B later can be estimated accurately, and the charge rate of the battery B can be estimated accurately.

<Modification 2>
When the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 (ratio r1) is used as the ratio r, and when the voltage of the battery B during the pause period rises, the previous charge rate estimation process is performed. In comparison, when the first voltage OCV1 and the second voltage OCV2 increase while the voltage difference between the first voltage OCV1 and the second voltage OCV2 is kept constant, the ratio r is assumed to decrease.

Further, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 (ratio r1) is taken as the ratio r, and when the voltage of the battery B during the rest period drops, the previous charge rate estimation Compared with the processing, when the first voltage OCV1 and the second voltage OCV2 become larger while the voltage difference between the first voltage OCV1 and the second voltage OCV2 is kept constant, the ratio r becomes larger. To do.

Further, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 (ratio r2) is taken as the ratio r, and when the voltage of the battery B during the rest period rises, the previous charge rate estimation Compared with the processing, when the first voltage OCV1 and the second voltage OCV2 become larger while the voltage difference between the first voltage OCV1 and the second voltage OCV2 is kept constant, the ratio r becomes larger. To do.

Further, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 (ratio r2) is taken as the ratio r, and when the voltage of the battery B during the rest period drops, the previous charge rate estimation Compared with the processing, when the first voltage OCV1 and the second voltage OCV2 become larger while the voltage difference between the first voltage OCV1 and the second voltage OCV2 is kept constant, the ratio r becomes smaller. To do.

FIG. 7 is a flowchart showing an example of the open circuit voltage estimation process in the second modification.
First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is increasing (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the ratio r and the coefficient a are multiplied. (S13).

Next, when the estimation unit 5 determines that the ratio r obtained in S12 is equal to or less than the threshold value rth (S31: Yes), the estimation unit 5 adds the value multiplied by S13 to the first voltage OCV1 or the second voltage OCV2. The value obtained by adding the first correction value to the result is used as the open circuit voltage of the battery B after the polarization is eliminated (S32).

On the other hand, when the estimation unit 5 determines that the ratio r obtained in S12 is larger than the threshold value rth (S31: No), the result of adding the value multiplied by S13 to the first voltage OCV1 or the second voltage OCV2. The value obtained by adding the second correction value smaller than the first correction value to the first correction value is taken as the open circuit voltage of the battery B after the polarization is eliminated (S33).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the estimation unit 5 obtains the ratio r and the coefficient b (S15), and multiplies the ratio r and the coefficient b. (S16).

Next, when the estimation unit 5 determines that the ratio r obtained in S15 is equal to or less than the threshold value rth (S34: Yes), the estimation unit 5 subtracts the value multiplied by S16 from the first voltage OCV1 or the second voltage OCV2. The value obtained by subtracting the first correction value from the result is used as the open circuit voltage of the battery B after the polarization is eliminated (S35).

On the other hand, when the estimation unit 5 determines that the ratio r obtained in S15 is larger than the threshold value rth (S34: No), the result of subtracting the value multiplied by S16 from the first voltage OCV1 or the second voltage OCV2. The value obtained by subtracting the second correction value, which is smaller than the first correction value, is used as the open circuit voltage of the battery B after the polarization is eliminated (S36).

The estimation unit 5 may be configured to increase the correction value as the ratio r decreases and decrease the correction value as the ratio r increases.
According to the open-circuit voltage estimation process shown in FIG. 7, when the ratio r is small, the correction value can be increased, and when the ratio r is large, the correction value can be decreased. Therefore, after the polarization is eliminated due to the fluctuation of the ratio r. Fluctuations in the estimated value of the open circuit voltage of the battery B can be suppressed. As a result, even if the ratio r fluctuates due to noise contained in the voltage V detected by the voltage detection unit 2, the fluctuation of the open circuit voltage of the battery B after the polarization is eliminated can be suppressed, so that the polarization is eliminated. The open circuit voltage of the battery B later can be estimated accurately, and the charge rate of the battery B can be estimated accurately.

<Modification example 3>
In the battery B, the polarization elimination time becomes longer when the voltage V detected by the voltage detection unit 2 becomes smaller at the time t0 shown in FIG. 2A or FIG. 2B as compared with the previous charge rate estimation process. As the voltage V detected by the voltage detection unit 2 increases at time t0, the polarization elimination time becomes shorter. Further, the battery B has a characteristic that the fluctuation range of the voltage due to polarization becomes constant regardless of the magnitude of the voltage V detected by the voltage detection unit 2 at time t0. When the battery B has these characteristics, the voltage of the battery B gradually rises as the polarization elimination time becomes longer, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A are It becomes smaller. Further, as the polarization elimination time becomes longer, the voltage of the battery B gradually decreases, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become large. On the other hand, when the polarization elimination time is shortened, the voltage of the battery B rises sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A become large. Further, when the polarization elimination time is shortened, the voltage of the battery B drops sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become smaller.

FIG. 8 is a flowchart showing an example of the open circuit voltage estimation process in the modified example 3.
<When the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 (ratio r1) is defined as the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller and the depolarization time of the battery B becomes smaller. It is assumed that the ratio r increases as the first voltage OCV1 and the second voltage OCV2 become shorter and larger. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r increases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is rising (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the first voltage OCV1 is the first. If it is determined that the voltage is equal to or less than the threshold Vth of, or if it is determined that the second voltage OCV2 is equal to or less than the second threshold Vth (S41: Yes), the coefficient a is set to the first coefficient a (S42) and the ratio r And the coefficient a are multiplied (S13), and the result of adding the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a is the open circuit voltage of the battery B after the polarization is eliminated. (S14). The first threshold value Vth and the second threshold value Vth may be the same value or different values from each other.

On the other hand, when the estimation unit 5 determines that the first voltage OCV1 is larger than the first threshold Vth, or determines that the second voltage OCV2 is larger than the second threshold Vth (S41: No), Let the coefficient a be the second coefficient a smaller than the first coefficient a (S43), multiply the ratio r by the coefficient a (S13), and add the ratio r to the first voltage OCV1 or the second voltage OCV2. The result of adding the value obtained by multiplying the coefficient a by the coefficient a is used as the open circuit voltage of the battery B after the polarization is eliminated (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the first voltage OCV1 is the first. If it is determined that the voltage is equal to or less than the threshold Vth of, or if it is determined that the second voltage OCV2 is equal to or less than the second threshold Vth (S44: Yes), the coefficient b is set to the first coefficient b (S45) and the ratio r And the coefficient b (S16), and the result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 is the open circuit voltage of the battery B after the polarization is eliminated. (S17).

On the other hand, when the estimation unit 5 determines that the first voltage OCV1 is larger than the first threshold Vth, or determines that the second voltage OCV2 is larger than the second threshold Vth (S44: No), Let the coefficient b be a second coefficient b smaller than the first coefficient b (S46), multiply the ratio r by the coefficient b (S16), and from the first voltage OCV1 or the second voltage OCV2, the ratio r The result of subtracting the value obtained by multiplying by the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

The estimation unit 5 increases the coefficients a and b as the first voltage OCV1 or the second voltage OCV decreases, and increases the coefficients a and b as the first voltage OCV1 or the second voltage OCV increases. It may be configured to be small.

According to the open-circuit voltage estimation process shown in FIG. 8, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is defined as the ratio r, when the first voltage OCV1 or the second voltage OCV2 becomes smaller, When the coefficients a and b are increased and the first voltage OCV1 or the second voltage OCV2 is increased, the coefficients a and b can be decreased.

Therefore, when the first voltage OCV1 or the second voltage OCV2 is smaller than the previous charge rate estimation process, that is, when the ratio r is smaller, the coefficients a and b can be increased, so that the polarization is eliminated. The estimated value of the open circuit voltage of the battery B later can be brought close to the actual value.

Further, when the first voltage OCV1 or the second voltage OCV2 is larger than the previous charge rate estimation process, that is, when the ratio r is larger, the coefficients a and b can be reduced, so that the polarization is eliminated. The estimated value of the open circuit voltage of the battery B later can be brought close to the actual value.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.
<When the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 (ratio r2) is the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes larger and the depolarization time of the battery B becomes longer. As the voltage becomes shorter and the first voltage OCV1 and the second voltage OCV2 become larger, the ratio r becomes smaller. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r decreases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r is assumed to be larger.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is rising (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the first voltage OCV1 is the first. If it is determined that the voltage is equal to or less than the threshold Vth of, or if it is determined that the second voltage OCV2 is equal to or less than the second threshold Vth (S41: Yes), the coefficient a is set to the first coefficient a (S42) and the ratio r And the coefficient a are multiplied (S13), and the result of adding the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a is the open circuit voltage of the battery B after the polarization is eliminated. (S14). The first threshold value Vth and the second threshold value Vth may be the same value or different values from each other.

On the other hand, when the estimation unit 5 determines that the first voltage OCV1 is larger than the first threshold Vth, or determines that the second voltage OCV2 is larger than the second threshold Vth (S41: No), Let the coefficient a be the second coefficient a larger than the first coefficient a (S43), multiply the ratio r by the coefficient a (S13), and add the ratio r to the first voltage OCV1 or the second voltage OCV2. The result of adding the value obtained by multiplying the coefficient a by the coefficient a is used as the open circuit voltage of the battery B after the polarization is eliminated (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the first voltage OCV1 is the first. If it is determined that the voltage is equal to or less than the threshold Vth of, or if it is determined that the second voltage OCV2 is equal to or less than the second threshold Vth (S44: Yes), the coefficient b is set to the first coefficient b (S45) and the ratio r And the coefficient b (S16), and the result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 is the open circuit voltage of the battery B after the polarization is eliminated. (S17).

On the other hand, when the estimation unit 5 determines that the first voltage OCV1 is larger than the first threshold Vth, or determines that the second voltage OCV2 is larger than the second threshold Vth (S44: No), Let the coefficient b be the second coefficient b larger than the first coefficient b (S46), multiply the ratio r by the coefficient b (S16), and from the first voltage OCV1 or the second voltage OCV2, the ratio r The result of subtracting the value obtained by multiplying by the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

The estimation unit 5 reduces the coefficients a and b as the first voltage OCV1 or the second voltage OCV becomes smaller, and sets the coefficients a and b as the first voltage OCV1 or the second voltage OCV becomes larger. It may be configured to be large.

According to the open-circuit voltage estimation process shown in FIG. 8, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is defined as the ratio r, when the first voltage OCV1 or the second voltage OCV2 becomes smaller, When the coefficients a and b are reduced and the first voltage OCV1 or the second voltage OCV2 is increased, the coefficients a and b can be increased.

Therefore, when the first voltage OCV1 or the second voltage OCV2 is smaller than the previous charge rate estimation process, that is, when the ratio r is large, the coefficients a and b can be reduced, so that the polarization is eliminated. The estimated value of the open circuit voltage of the battery B later can be brought close to the actual value.

Further, when the first voltage OCV1 or the second voltage OCV2 is larger than the previous charge rate estimation process, that is, when the ratio r is smaller, the coefficients a and b can be increased, so that the polarization is eliminated. The estimated value of the open circuit voltage of the battery B later can be brought close to the actual value.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

<Modification example 4>
In the battery B, the polarization elimination time becomes longer when the voltage V detected by the voltage detection unit 2 becomes smaller at the time t0 shown in FIG. 2A or FIG. 2B as compared with the previous charge rate estimation process. As the voltage V detected by the voltage detection unit 2 increases at time t0, the polarization elimination time becomes shorter. Further, the battery B has a characteristic that the fluctuation range of the voltage due to polarization becomes constant regardless of the magnitude of the voltage V detected by the voltage detection unit 2 at time t0. When the battery B has these characteristics, the voltage of the battery B gradually rises as the polarization elimination time becomes longer, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A are It becomes smaller. Further, as the polarization elimination time becomes longer, the voltage of the battery B gradually decreases, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become large. On the other hand, when the polarization elimination time is shortened, the voltage of the battery B rises sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A become large. Further, when the polarization elimination time is shortened, the voltage of the battery B drops sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become smaller. Further, the absolute value of the difference between the first voltage OCV1 and the second voltage OCV2 is taken as the amount of change in the open circuit voltage of the battery B. Further, the absolute value of the difference between the charge rate SOC1 and the charge rate SOC2 is used as the amount of change in the charge rate of the battery B. Further, the result of dividing the change amount of the open circuit voltage of the battery B by the change amount of the charge rate of the battery B is defined as the change rate R of the change amount of the open circuit voltage of the battery B with respect to the change amount of the charge rate of the battery B. .. Further, as shown in FIG. 3, in the battery B, the rate of change R in the region a where the open circuit voltage and the charge rate of the battery B are large is larger than the rate of change R in the region b where the open circuit voltage and the charge rate of the battery B are small. It shall have the characteristic of being large.

FIG. 9 is a flowchart showing an example of the open circuit voltage estimation process in the modified example 4.
<When the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 (ratio r1) is defined as the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller and the depolarization time of the battery B becomes smaller. It is assumed that the ratio r increases as the first voltage OCV1 and the second voltage OCV2 become shorter and larger. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r increases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is rising (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the rate of change R is greater than the threshold Rth. If it is determined to be large (S51: Yes), the coefficient a is set to the first coefficient a (S52), the ratio r is multiplied by the coefficient a (S13), and the ratio is added to the first voltage OCV1 or the second voltage OCV2. The result of adding the value obtained by multiplying r by the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14).

On the other hand, when the estimation unit 5 determines that the rate of change R is equal to or less than the threshold Rth (S51: No), the coefficient a is set to the second coefficient a smaller than the first coefficient a (S53), and the ratio r and the coefficient Multiply by a (S13) and add the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a to obtain the open circuit voltage of the battery B after polarization elimination. (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the rate of change R is higher than the threshold Rth. If it is determined to be large (S54: Yes), the coefficient b is set to the first coefficient b (S55), the ratio r is multiplied by the coefficient b (S16), and the ratio is calculated from the first voltage OCV1 or the second voltage OCV2. The result of subtracting the value obtained by multiplying r by the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the rate of change R is equal to or less than the threshold Rth (S54: No), the coefficient b is set to a second coefficient b smaller than the first coefficient b (S56), and the ratio r and the coefficient. Multiply by b (S16) and subtract the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 to obtain the open circuit voltage of the battery B after polarization elimination. (S17).

The estimation unit 5 may be configured to increase the coefficients a and b as the rate of change R increases, and decrease the coefficients a and b as the rate of change R decreases.
According to the open circuit voltage estimation process shown in FIG. 9, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is defined as the ratio r, when the rate of change R increases, the coefficients a and b are increased. When the rate of change R becomes small, the coefficients a and b can be made small.

Therefore, when the rate of change R is larger, that is, when the ratio r is smaller than in the previous charge rate estimation process, the coefficients a and b can be increased, so that the open circuit of the battery B after the polarization is eliminated. The estimated value of the voltage can be brought close to the actual value.

Further, when the rate of change R becomes smaller, that is, when the ratio r becomes larger than in the previous charge rate estimation process, the coefficients a and b can be made smaller, so that the open circuit of the battery B after the polarization is eliminated. The estimated value of the voltage can be brought close to the actual value.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

<When the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 (ratio r2) is the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes larger and the depolarization time of the battery B becomes longer. As the voltage becomes shorter and the first voltage OCV1 and the second voltage OCV2 become larger, the ratio r becomes smaller. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r decreases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r is assumed to be larger.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is rising (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the rate of change R is greater than the threshold Rth. If it is determined to be large (S51: Yes), the coefficient a is set to the first coefficient a (S52), the ratio r is multiplied by the coefficient a (S13), and the ratio is added to the first voltage OCV1 or the second voltage OCV2. The result of adding the value obtained by multiplying r by the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14).

On the other hand, when the estimation unit 5 determines that the rate of change R is equal to or less than the threshold Rth (S51: No), the coefficient a is set to a second coefficient a larger than the first coefficient a (S53), and the ratio r and the coefficient. Multiply by a (S13) and add the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a to obtain the open circuit voltage of the battery B after polarization elimination. (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the rate of change R is higher than the threshold Rth. If it is determined to be large (S54: Yes), the coefficient b is set to the first coefficient b (S55), the ratio r is multiplied by the coefficient b (S16), and the ratio is calculated from the first voltage OCV1 or the second voltage OCV2. The result of subtracting the value obtained by multiplying r by the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the rate of change R is equal to or less than the threshold Rth (S54: No), the coefficient b is set to a second coefficient b larger than the first coefficient b (S56), and the ratio r and the coefficient. Multiply by b (S16) and subtract the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 to obtain the open circuit voltage of the battery B after polarization elimination. (S17).

The estimation unit 5 may be configured so that the coefficients a and b decrease as the rate of change R increases, and the coefficients a and b increase as the rate of change R decreases.
According to the open circuit voltage estimation process shown in FIG. 9, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is defined as the ratio r, when the rate of change R increases, the coefficients a and b are reduced. When the rate of change R becomes small, the coefficients a and b can be increased.

Therefore, when the rate of change R is larger, that is, when the ratio r is larger than in the previous charge rate estimation process, the coefficients a and b can be made smaller, so that the open circuit of the battery B after the polarization is eliminated. The estimated value of the voltage can be brought close to the actual value.

Further, when the rate of change R is smaller than the previous charge rate estimation process, that is, when the ratio r is smaller, the coefficients a and b can be increased, so that the open circuit of the battery B after the polarization is eliminated. The estimated value of the voltage can be brought close to the actual value.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

<Modification 5>
The polarization elimination time of the battery B becomes longer when the temperature T detected by the temperature detection unit 3 is lower at the time t0 shown in FIG. 2A or FIG. 2B as compared with the previous charge rate estimation process. As the temperature T detected by the temperature detection unit 3 increases at time t0, the polarization elimination time becomes shorter. Further, the battery B has a characteristic that the fluctuation range of the voltage due to polarization becomes constant regardless of the magnitude of the temperature T detected by the temperature detection unit 3 at time t0. When the battery B has these characteristics, the voltage of the battery B gradually rises as the polarization elimination time becomes longer, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A are It becomes smaller. Further, as the polarization elimination time becomes longer, the voltage of the battery B gradually decreases, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become large. On the other hand, when the polarization elimination time is shortened, the voltage of the battery B rises sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A become large. Further, when the polarization elimination time is shortened, the voltage of the battery B drops sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become smaller.

FIG. 10 is a flowchart showing an example of the charge rate estimation process in the modified example 5.
First, the estimation unit 5 sets the first and second predetermined times according to the temperature T detected by the temperature detection unit 3 (S100). Since S101 to S112 shown in FIG. 10 are the same processes as S101 to S112 shown in FIG. 4, the description thereof will be omitted.

For example, the estimation unit 5 sets the first predetermined time and the second predetermined time when the temperature T detected by the temperature detection unit 3 at the time t0 is a second temperature higher than the first temperature at the time t0. The temperature T detected by the temperature detection unit 3 is set to a time shorter than the first predetermined time and the second predetermined time when the temperature T is the first temperature.

As a result, when the temperature of the battery B rises, the first predetermined time and the second predetermined time can be shortened. Therefore, when the voltage of the battery B rises, the first voltage OCV1 and the second voltage OCV2 When the voltage of the battery B drops, the first voltage OCV1 and the second voltage OCV2 can be increased.

Further, when the temperature of the battery B becomes low, the first predetermined time and the second predetermined time can be lengthened. Therefore, when the voltage of the battery B rises, the first voltage OCV1 and the second voltage OCV2 are used. When the voltage of the battery B drops, the first voltage OCV1 and the second voltage OCV2 can be lowered.

That is, since the fluctuations of the first voltage OCV1 and the second voltage OCV2 due to the fluctuation of the temperature of the battery B can be suppressed, the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately, and the battery B can be estimated accurately. The charge rate of the battery can be estimated accurately.

Further, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is taken as the ratio r, when the voltage of the battery B during the rest period rises, the polarization elimination time of the battery B becomes longer and the first When the voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller, the polarization elimination time of the battery B becomes shorter, and when the first voltage OCV1 and the second voltage OCV2 become larger, the ratio r becomes larger. .. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r increases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller.

Further, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is defined as the ratio r, when the voltage of the battery B during the rest period rises, the polarization elimination time of the battery B becomes longer and the first When the voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes larger, the polarization elimination time of the battery B becomes shorter, and when the first voltage OCV1 and the second voltage OCV2 become larger, the ratio r becomes smaller. .. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r decreases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r is assumed to be larger.

Therefore, for example, the estimation unit 5 sets the first predetermined time and the second predetermined time when the temperature T detected by the temperature detection unit 3 at time t0 is a second temperature higher than the first temperature. The difference is set to a time shorter than the difference between the first predetermined time and the second predetermined time when the temperature T detected by the temperature detection unit 3 at time t0 is the first temperature.

As a result, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is taken as the ratio r, the difference between the first predetermined time and the second predetermined time becomes shorter as the temperature of the battery B rises. Therefore, the difference between the first voltage OCV1 and the second voltage OCV2 can be reduced, the ratio r when the voltage of the battery B during the pause period rises is small, and the battery B during the pause period can be reduced. The ratio r when the voltage of is lowered can be increased.

Further, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is taken as the ratio r, when the temperature of the battery B becomes low, the difference between the first predetermined time and the second predetermined time is lengthened. Therefore, the difference between the first voltage OCV1 and the second voltage OCV2 can be increased, the ratio r when the voltage of the battery B during the hibernation period rises can be increased, and the battery B during the hibernation period can be increased. The ratio r when the voltage drops can be reduced.

Further, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is taken as the ratio r, when the temperature of the battery B becomes high, the difference between the first predetermined time and the second predetermined time is shortened. Therefore, the difference between the first voltage OCV1 and the second voltage OCV2 can be reduced, the ratio r when the voltage of the battery B during the pause period rises is large, and the battery B during the pause period can be increased. The ratio r when the voltage drops can be reduced.

Further, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is taken as the ratio r, when the temperature of the battery B becomes low, the difference between the first predetermined time and the second predetermined time is lengthened. Therefore, the difference between the first voltage OCV1 and the second voltage OCV2 can be increased, the ratio r when the voltage of the battery B during the pause period rises can be made small, and the battery B during the pause period can be reduced. The ratio r when the voltage drops can be increased.

That is, since the fluctuation of the ratio r due to the fluctuation of the temperature of the battery B can be suppressed, the open circuit voltage of the battery B after the polarization is eliminated can be estimated accurately, and the charge rate of the battery B can be estimated accurately. Can be done.

<Modification 6>
The polarization elimination time of the battery B becomes longer when the temperature T detected by the temperature detection unit 3 is lower at the time t0 shown in FIG. 2A or FIG. 2B as compared with the previous charge rate estimation process. As the temperature T detected by the temperature detection unit 3 increases at time t0, the polarization elimination time becomes shorter. Further, the battery B has a characteristic that the fluctuation range of the voltage due to polarization becomes constant regardless of the magnitude of the temperature T detected by the temperature detection unit 3 at time t0. When the battery B has these characteristics, the voltage of the battery B gradually rises as the polarization elimination time becomes longer, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A are It becomes smaller. Further, as the polarization elimination time becomes longer, the voltage of the battery B gradually decreases, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become large. On the other hand, when the polarization elimination time is shortened, the voltage of the battery B rises sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A become large. Further, when the polarization elimination time is shortened, the voltage of the battery B drops sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become smaller.

FIG. 11 is a flowchart showing an example of the open circuit voltage estimation process in the modified example 6.
<When the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 (ratio r1) is defined as the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller and the depolarization time of the battery B becomes smaller. It is assumed that the ratio r increases as the first voltage OCV1 and the second voltage OCV2 become shorter and larger. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r increases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is increasing (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the temperature detection unit 3 detects the voltage V. When it is determined that the temperature T is equal to or less than the threshold Tth (S61: Yes), the coefficient a is set to the first coefficient a (S62), the ratio r is multiplied by the coefficient a (S13), and the first voltage OCV1 or the first voltage is used. The result of adding the value obtained by multiplying the voltage OCV2 of 2 by the ratio r and the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14). For example, the estimation unit 5 sets the temperature detected by the temperature detection unit 3 as the temperature T at the time t0 shown in FIG. 2 (a) or FIG. 2 (b).

On the other hand, when the estimation unit 5 determines that the temperature T detected by the temperature detection unit 3 is larger than the threshold value Tth (S61: No), the coefficient a is set to a second coefficient a smaller than the first coefficient a (S61: No). S63), the ratio r and the coefficient a are multiplied (S13), and the result of adding the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a is the result of the battery after polarization elimination. Let the open circuit voltage of B be (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the temperature detection unit 3 detects the voltage V. When it is determined that the temperature T is equal to or less than the threshold value Tth (S64: Yes), the coefficient b is set as the first coefficient b (S65), the ratio r is multiplied by the coefficient b (S16), and the first voltage OCV1 or the first voltage is obtained. The result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the voltage OCV2 of 2 is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the temperature T detected by the temperature detection unit 3 is larger than the threshold value Tth (S64: No), the coefficient b is set to a second coefficient b larger than the first coefficient b (S64: No). S66), the ratio r and the coefficient b are multiplied (S16), and the result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 is obtained from the battery after polarization elimination. Let the open circuit voltage of B be (S17).

The estimation unit 5 may be configured such that the lower the temperature of the battery B, the larger the coefficient a and the smaller the coefficient b, and the higher the temperature of the battery B, the smaller the coefficient a and the larger the coefficient b. Good.

According to the open-circuit voltage estimation process shown in FIG. 11, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is taken as the ratio r, when the temperature of the battery B becomes low, the coefficient a becomes large and the coefficient b becomes large. When the temperature of the battery B becomes high, the coefficient a can be made small and the coefficient b can be made large.

Therefore, the coefficient a can be increased when the temperature of the battery B is lower than that of the previous charge rate estimation process, that is, when the ratio r is smaller when the voltage of the battery B is increased during the rest period. When the ratio r becomes large when the voltage of the battery B drops during the rest period, the coefficient b can be reduced, so that the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is brought closer to the actual value. be able to.

Further, the coefficient a can be reduced when the temperature of the battery B is higher than that of the previous charge rate estimation process, that is, when the ratio r becomes larger when the voltage of the battery B rises during the rest period. When the ratio r becomes smaller when the voltage of the battery B drops during the rest period, the coefficient b can be increased, so that the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is brought closer to the actual value. be able to.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

<When the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 (ratio r2) is the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes larger and the depolarization time of the battery B becomes longer. As the voltage becomes shorter and the first voltage OCV1 and the second voltage OCV2 become larger, the ratio r becomes smaller. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r decreases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r is assumed to be larger.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is increasing (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the temperature detection unit 3 detects the voltage V. When it is determined that the temperature T is equal to or less than the threshold Tth (S61: Yes), the coefficient a is set to the first coefficient a (S62), the ratio r is multiplied by the coefficient a (S13), and the first voltage OCV1 or the first voltage is used. The result of adding the value obtained by multiplying the voltage OCV2 of 2 by the ratio r and the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14). For example, the estimation unit 5 sets the temperature detected by the temperature detection unit 3 as the temperature T at the time t0 shown in FIG. 2 (a) or FIG. 2 (b).

On the other hand, when the estimation unit 5 determines that the temperature T detected by the temperature detection unit 3 is larger than the threshold value Tth (S61: No), the coefficient a is set to a second coefficient a larger than the first coefficient a (S61: No). S63), the ratio r and the coefficient a are multiplied (S13), and the result of adding the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a is the result of the battery after polarization elimination. Let the open circuit voltage of B be (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the temperature detection unit 3 detects the voltage V. When it is determined that the temperature T is equal to or less than the threshold value Tth (S64: Yes), the coefficient b is set as the first coefficient b (S65), the ratio r is multiplied by the coefficient b (S16), and the first voltage OCV1 or the first voltage is obtained. The result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the voltage OCV2 of 2 is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the temperature T detected by the temperature detection unit 3 is larger than the threshold value Tth (S64: No), the coefficient b is set to a second coefficient b smaller than the first coefficient b (S64: No). S66), the ratio r and the coefficient b are multiplied (S16), and the result of subtracting the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 is obtained from the battery after polarization elimination. Let the open circuit voltage of B be (S17).

The estimation unit 5 may be configured so that the lower the temperature of the battery B, the smaller the coefficient a and the larger the coefficient b, and the higher the temperature of the battery B, the larger the coefficient a and the smaller the coefficient b. Good.

According to the open-circuit voltage estimation process shown in FIG. 11, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is taken as the ratio r, when the temperature of the battery B becomes low, the coefficient a becomes small and the coefficient b becomes small. When the temperature of the battery B becomes high, the coefficient a can be increased and the coefficient b can be decreased.

Therefore, the coefficient a can be reduced when the temperature of the battery B is lower than that of the previous charge rate estimation process, that is, when the ratio r is larger when the voltage of the battery B is increased during the rest period. When the ratio r becomes smaller when the voltage of the battery B drops during the rest period, the coefficient b can be increased, so that the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is brought closer to the actual value. be able to.

Further, the coefficient a can be increased when the temperature of the battery B is higher than that of the previous charge rate estimation process, that is, when the ratio r is smaller when the voltage of the battery B is increased during the rest period. When the ratio r becomes large when the voltage of the battery B drops during the rest period, the coefficient b can be reduced, so that the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is brought closer to the actual value. be able to.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

<Modification 7>
When the degree of deterioration D of the battery B obtained at time t0 shown in FIG. 2A or FIG. 2B is lower than that of the previous charge rate estimation process, the depolarization time of the battery B becomes shorter, and the time becomes shorter. It is assumed that the higher the degree of deterioration D of the battery B required at t0, the longer the polarization elimination time. Further, the battery B has a characteristic that the fluctuation range of the voltage due to polarization becomes constant regardless of the magnitude of the deterioration degree D of the battery B obtained at time t0. When the battery B has these characteristics, the voltage of the battery B gradually rises as the polarization elimination time becomes longer, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A are It becomes smaller. Further, as the polarization elimination time becomes longer, the voltage of the battery B gradually decreases, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become large. On the other hand, when the polarization elimination time is shortened, the voltage of the battery B rises sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2A become large. Further, when the polarization elimination time is shortened, the voltage of the battery B drops sharply, so that the first voltage OCV1 and the second voltage OCV2 shown in FIG. 2B become smaller.

FIG. 12 is a flowchart showing an example of the open circuit voltage estimation process in the modified example 7.
<When the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 (ratio r1) is defined as the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller and the depolarization time of the battery B becomes smaller. It is assumed that the ratio r increases as the first voltage OCV1 and the second voltage OCV2 become shorter and larger. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r increases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes smaller.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is increasing (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the deterioration degree D of the battery B is a threshold value. When it is determined that the voltage is Dth or less (S71: Yes), the coefficient a is set to the first coefficient a (S72), the ratio r is multiplied by the coefficient a (S13), and the first voltage OCV1 or the second voltage OCV2 is obtained. The result of adding the value obtained by multiplying the ratio r and the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14). For example, the estimation unit 5 divides the voltage V detected by the voltage detection unit 2 by the current I detected by the current detection unit 1 at time t0 shown in FIG. 2 (a) or FIG. 2 (b). , The internal resistance of the battery B, and the result of dividing the internal resistance by the internal resistance of the battery B at the start of using the battery pack is defined as the degree of deterioration D.

On the other hand, when the estimation unit 5 determines that the deterioration degree D is larger than the threshold Dth (S71: No), the coefficient a is set to the second coefficient a larger than the first coefficient a (S73), and the ratio r and the coefficient Multiply by a (S13) and add the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a to obtain the open circuit voltage of the battery B after polarization elimination. (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the degree of deterioration D is equal to or less than the threshold Dth. If it is determined to be (S74: Yes), the coefficient b is set to the first coefficient b (S75), the ratio r is multiplied by the coefficient b (S16), and the ratio is calculated from the first voltage OCV1 or the second voltage OCV2. The result of subtracting the value obtained by multiplying r by the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the deterioration degree D is larger than the threshold Dth (S74: No), the coefficient b is set to the second coefficient b smaller than the first coefficient b (S76), and the ratio r and the coefficient Multiply by b (S16) and subtract the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 to obtain the open circuit voltage of the battery B after polarization elimination. (S17).

The estimation unit 5 increases the coefficient a and increases the coefficient b as the deterioration degree D of the battery B decreases, and increases the coefficient a and decreases the coefficient b as the deterioration degree D of the battery B increases. It may be configured.

According to the open circuit voltage estimation process shown in FIG. 12, when the value obtained by dividing the second voltage OCV2 by the first voltage OCV1 is taken as the ratio r, when the deterioration degree D of the battery B becomes smaller, the coefficient a becomes smaller. When the coefficient b is increased and the degree of deterioration D of the battery B is increased, the coefficient a can be increased and the coefficient b can be decreased.

Therefore, when the degree of deterioration D of the battery B is smaller than that of the previous charge rate estimation process, that is, when the ratio r is large when the voltage of the battery B is increased during the rest period, the coefficient a is reduced. When the ratio r becomes smaller when the voltage of the battery B drops during the rest period, the coefficient b can be increased. Therefore, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the actual value. Can be approached to.

Further, when the degree of deterioration D of the battery B is larger than that of the previous charge rate estimation process, that is, when the ratio r is smaller when the voltage of the battery B is increased during the rest period, the coefficient a is increased. When the ratio r becomes large when the voltage of the battery B drops during the pause period, the coefficient b can be reduced. Therefore, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the actual value. Can be approached to.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

<When the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 (ratio r2) is the ratio r>
When the voltage of the battery B rises during the rest period, the depolarization time of the battery B becomes longer, and when the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r becomes larger and the depolarization time of the battery B becomes longer. As the voltage becomes shorter and the first voltage OCV1 and the second voltage OCV2 become larger, the ratio r becomes smaller. Further, when the voltage of the battery B drops during the pause period, the polarization elimination time of the battery B becomes long, and when the first voltage OCV1 and the second voltage OCV2 increase, the ratio r decreases and the polarization of the battery B is eliminated. As the time becomes shorter and the first voltage OCV1 and the second voltage OCV2 become smaller, the ratio r is assumed to be larger.

First, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is increasing (S11: Yes), the ratio r and the coefficient a are obtained (S12), and the deterioration degree D of the battery B is a threshold value. When it is determined that the voltage is Dth or less (S71: Yes), the coefficient a is set to the first coefficient a (S72), the ratio r is multiplied by the coefficient a (S13), and the first voltage OCV1 or the second voltage OCV2 is obtained. The result of adding the value obtained by multiplying the ratio r and the coefficient a is taken as the open circuit voltage of the battery B after the polarization is eliminated (S14). For example, the estimation unit 5 divides the voltage V detected by the voltage detection unit 2 by the current I detected by the current detection unit 1 at time t0 shown in FIG. 2 (a) or FIG. 2 (b). , The internal resistance of the battery B, and the result of dividing the internal resistance by the internal resistance of the battery B at the start of using the battery pack is defined as the degree of deterioration D.

On the other hand, when the estimation unit 5 determines that the deterioration degree D is larger than the threshold Dth (S71: No), the coefficient a is set to the second coefficient a smaller than the first coefficient a (S73), and the ratio r and the coefficient Multiply by a (S13) and add the value obtained by multiplying the first voltage OCV1 or the second voltage OCV2 by the ratio r and the coefficient a to obtain the open circuit voltage of the battery B after polarization elimination. (S14).

Further, when the estimation unit 5 determines that the voltage V detected by the voltage detection unit 2 is decreasing (S11: No), the ratio r and the coefficient b are obtained (S15), and the degree of deterioration D is equal to or less than the threshold Dth. If it is determined to be (S74: Yes), the coefficient b is set to the first coefficient b (S75), the ratio r is multiplied by the coefficient b (S16), and the ratio is calculated from the first voltage OCV1 or the second voltage OCV2. The result of subtracting the value obtained by multiplying r by the coefficient b is taken as the open circuit voltage of the battery B after the polarization is eliminated (S17).

On the other hand, when the estimation unit 5 determines that the deterioration degree D is larger than the threshold Dth (S74: No), the coefficient b is set to the second coefficient b larger than the first coefficient b (S76), and the ratio r and the coefficient Multiply by b (S16) and subtract the value obtained by multiplying the ratio r and the coefficient b from the first voltage OCV1 or the second voltage OCV2 to obtain the open circuit voltage of the battery B after polarization elimination. (S17).

The estimation unit 5 increases the coefficient a and decreases the coefficient a as the deterioration degree D of the battery B decreases, and decreases the coefficient a and increases the coefficient b as the deterioration degree D of the battery B increases. It may be configured.

According to the open circuit voltage estimation process shown in FIG. 12, when the value obtained by dividing the first voltage OCV1 by the second voltage OCV2 is taken as the ratio r, when the deterioration degree D of the battery B becomes smaller, the coefficient a becomes larger. When the coefficient b is reduced and the degree of deterioration D of the battery B is increased, the coefficient a can be reduced and the coefficient b can be increased.

Therefore, when the deterioration degree D of the battery B is smaller than that of the previous charge rate estimation process, that is, when the ratio r is smaller when the voltage of the battery B is increased during the rest period, the coefficient a is increased. When the ratio r becomes large when the voltage of the battery B drops during the pause period, the coefficient b can be reduced. Therefore, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the actual value. Can be approached to.

Further, when the degree of deterioration D of the battery B is larger than that of the previous charge rate estimation process, that is, when the ratio r is larger when the voltage of the battery B is increased during the rest period, the coefficient a is reduced. When the ratio r becomes smaller when the voltage of the battery B drops during the rest period, the coefficient b can be increased. Therefore, the estimated value of the open circuit voltage of the battery B after the polarization is eliminated is the actual value. Can be approached to.

As a result, the open circuit voltage of the battery B after the polarization is eliminated can be estimated with high accuracy, so that the charge rate of the battery B can be obtained with high accuracy.

1 Current detection unit 2 Voltage detection unit 3 Temperature detection unit 4 Storage unit 5 Estimator unit B Battery Ch Charger Lo Load

Claims (20)

Batteries and
A voltage detector that detects the voltage of the battery and
The first voltage detected by the voltage detection unit or the first voltage after the elapse of the first predetermined time from the start of the pause period in the pause period after the discharge of the battery is completed and before the polarization of the battery is eliminated. The ratio of the first voltage to the second voltage is added to the second voltage detected by the voltage detector after the lapse of the second predetermined time longer than the first predetermined time from the start of the pause period. An estimation unit that estimates the result of adding the value obtained by multiplying the coefficient as the open circuit voltage after depolarization of the battery.
A battery pack characterized by being equipped with. Batteries and
A voltage detector that detects the voltage of the battery and
The first voltage detected by the voltage detection unit or the first voltage after the lapse of the first predetermined time from the start of the pause period in the pause period after the charging of the battery is completed and before the polarization of the battery is eliminated. From the second voltage detected by the voltage detector after the lapse of the second predetermined time longer than the first predetermined time from the start of the pause period, the ratio of the first voltage to the second voltage is determined. An estimation unit that estimates the result of subtracting the value obtained by multiplying the coefficient as the open circuit voltage after depolarization of the battery.
A battery pack characterized by being equipped with. The battery pack according to claim 1 or 2.
The estimation unit
When the ratio is equal to or less than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the ratio is larger than the threshold value, the coefficient is set to a second coefficient smaller than the first coefficient. The battery pack according to claim 1.
The estimation unit
When the ratio is equal to or less than the threshold value, the value obtained by adding the first correction value to the result is estimated as the open circuit voltage after the polarization of the battery is eliminated.
When the ratio is larger than the threshold value, the value obtained by adding the second correction value smaller than the first correction value to the result is estimated as the open circuit voltage after the polarization of the battery is eliminated. Battery pack. The battery pack according to claim 2.
The estimation unit
When the ratio is equal to or less than the threshold value, the value obtained by subtracting the first correction value from the result is estimated as the open circuit voltage after the polarization of the battery is eliminated.
When the ratio is larger than the threshold value, a value obtained by subtracting a second correction value smaller than the first correction value from the result is estimated as an open circuit voltage after depolarization of the battery. Battery pack. The battery pack according to claim 1 or 2.
The ratio is a value obtained by dividing the second voltage by the first voltage.
The estimation unit
When the first voltage is equal to or less than the first threshold value, the coefficient is set as the first coefficient, and when the first voltage is larger than the first threshold value, the coefficient is larger than the first coefficient. Use a small second coefficient
Or
When the second voltage is equal to or less than the second threshold value, the coefficient is defined as the first coefficient, and when the second voltage is larger than the second threshold value, the coefficient is defined as the second coefficient. A battery pack that features that. The battery pack according to claim 1 or 2.
The ratio is a value obtained by dividing the first voltage by the second voltage.
The estimation unit
When the first voltage is equal to or less than the first threshold value, the coefficient is set as the first coefficient, and when the first voltage is larger than the first threshold value, the coefficient is larger than the first coefficient. As a large second coefficient
Or
When the second voltage is equal to or less than the second threshold value, the coefficient is defined as the first coefficient, and when the second voltage is larger than the second threshold value, the coefficient is defined as the second coefficient. A battery pack that features that. The battery pack according to claim 1 or 2.
The ratio is a value obtained by dividing the second voltage by the first voltage.
The estimation unit
When the change rate of the change amount of the open circuit voltage of the battery with respect to the change amount of the charge rate of the battery is larger than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the rate of change is equal to or less than the threshold value, the coefficient is set to a second coefficient smaller than the first coefficient. The battery pack according to claim 1 or 2.
The ratio is a value obtained by dividing the first voltage by the second voltage.
The estimation unit
When the change rate of the change amount of the open circuit voltage of the battery with respect to the change amount of the charge rate of the battery is larger than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the rate of change is equal to or less than the threshold value, the coefficient is set to a second coefficient larger than the first coefficient. The battery pack according to claim 1 or 2.
The estimation unit determines the first predetermined time when the temperature of the battery is a second temperature higher than the first temperature, and the first predetermined time when the temperature of the battery is the first temperature. A battery pack characterized by being set to a shorter time than the time. The battery pack according to claim 1 or 2.
The estimation unit sets the difference between the first predetermined time and the second predetermined time when the temperature of the battery is a second temperature higher than the first temperature, and the temperature of the battery is the first. A battery pack characterized in that the time is set shorter than the difference between the first predetermined time and the second predetermined time at the temperature of. The battery pack according to claim 1.
The ratio is a value obtained by dividing the second voltage by the first voltage.
The estimation unit
When the temperature of the battery is equal to or lower than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the temperature of the battery is higher than the threshold value, the coefficient is set to a second coefficient smaller than the first coefficient. The battery pack according to claim 2.
The ratio is a value obtained by dividing the second voltage by the first voltage.
The estimation unit
When the temperature of the battery is equal to or lower than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the temperature of the battery is larger than the threshold value, the coefficient is set to a second coefficient larger than the first coefficient. The battery pack according to claim 1.
The ratio is a value obtained by dividing the first voltage by the second voltage.
The estimation unit
When the temperature of the battery is equal to or lower than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the temperature of the battery is larger than the threshold value, the coefficient is set to a second coefficient larger than the first coefficient. The battery pack according to claim 2.
The ratio is a value obtained by dividing the first voltage by the second voltage.
The estimation unit
When the temperature of the battery is equal to or lower than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the temperature of the battery is higher than the threshold value, the coefficient is set to a second coefficient smaller than the first coefficient. The battery pack according to claim 1.
The ratio is a value obtained by dividing the second voltage by the first voltage.
The estimation unit
When the degree of deterioration of the battery is equal to or less than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the degree of deterioration of the battery is larger than the threshold value, the coefficient is set to a second coefficient larger than the first coefficient. The battery pack according to claim 2.
The ratio is a value obtained by dividing the second voltage by the first voltage.
The estimation unit
When the degree of deterioration of the battery is equal to or less than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the degree of deterioration of the battery is larger than the threshold value, the coefficient is set to a second coefficient smaller than the first coefficient. The battery pack according to claim 1.
The ratio is a value obtained by dividing the first voltage by the second voltage.
The estimation unit
When the degree of deterioration of the battery is equal to or less than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the degree of deterioration of the battery is larger than the threshold value, the coefficient is set to a second coefficient smaller than the first coefficient. The battery pack according to claim 2.
The ratio is a value obtained by dividing the first voltage by the second voltage.
The estimation unit
When the degree of deterioration of the battery is equal to or less than the threshold value, the coefficient is set as the first coefficient.
A battery pack characterized in that when the degree of deterioration of the battery is larger than the threshold value, the coefficient is set to a second coefficient larger than the first coefficient. The battery pack according to claim 1 or 2.
The battery pack is characterized in that the estimation unit updates the coefficient based on the voltage detected by the voltage detection unit when the polarization of the battery is eliminated.

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