JP2011106953A - Method for detecting battery capacity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting a battery capacity which enables detection of the full charging capacity of a battery with high accuracy. <P>SOLUTION: A battery capacity calculating device 1 detects the full charging capacity of the battery from a capacity change value of the battery between first detection timing and second detection timing, a change rate of the residual capacity of the battery calculated by an equivalent circuit model system and an integrated value of a current value. Herein the first and second detecting timings are so set as to avoid the condition wherein a modeling error due to an equivalent circuit model becomes large. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for a battery capacity detection method.

Patent Document 1 discloses a full charge capacity detection method for calculating battery capacity according to the following procedure.
1. Between the first detection timing and the second detection timing, the charge / discharge amount of electricity is calculated from the integrated value of the charge / discharge current of the battery.
2. The OCV (Open Circuit Voltage) at the first detection timing and the OCV at the second timing are detected, and the SOC (State Of Charge) of the battery is calculated from these OCVs.
3. The battery capacity CAPA is calculated from the following equation (B1) from the SOC fluctuation value (ΔSOC) and the charge / discharge amount (ΣI) at the first timing and the second timing.

CAPA = ΔAh / ΔSOC (B1)

JP 2008-241358 A

  However, in the technique described in Patent Document 1, a function or a map of the OCV characteristic with respect to the charge / discharge electric quantity is used for OCV detection. In this method, it is difficult to cope with characteristic changes due to changes in the battery over time, temperature changes, and the like, and an OCV detection error increases. As a result, there is a problem that the estimation accuracy of the battery capacity is deteriorated.

  Accordingly, an object of the present invention is to provide a battery capacity detection method that enables a highly accurate full charge capacity of a battery.

The invention according to claim 1 of the present invention that solves the above-described problem is a battery calculated by a capacity change value of the battery between the first detection timing and the second detection timing, and an equivalent circuit model method. The battery capacity detection method by the battery capacity detection device that detects the full charge capacity of the battery according to CAPA = ΔAh / ΔSOC from the rate of change of the remaining capacity of the battery, wherein the first detection timing and the second detection timing are: The error between the voltage estimated value based on the equivalent circuit model and the actual voltage value acquired from the voltage sensor is less than or equal to a predetermined error, and the actual current value acquired from the current sensor is less than or equal to a predetermined current value and within a predetermined period. The actual current fluctuation value is less than or equal to the predetermined current fluctuation value, the actual voltage fluctuation value within the predetermined period is less than or equal to the predetermined voltage fluctuation value, and the battery temperature acquired from the temperature sensor is equal to or lower than the predetermined current fluctuation value. It is above the battery temperature.
However, CAPA is the full charge capacity of the battery, ΔAh is the capacity change value of the battery between the first detection timing and the second detection timing, and ΔSOC is the first detection timing. The change rate of the remaining capacity of the battery calculated by the equivalent circuit model method between the second detection timing and the second detection timing.

  According to the first aspect of the invention, since the full charge capacity of the battery using the SOC calculated by the equivalent circuit model can be calculated in a situation avoiding the condition that the modeling error of the equivalent circuit model becomes large, It becomes possible to detect the full charge capacity of the battery with high accuracy following the change with time.

  The invention according to claim 2 is characterized in that the predetermined current value is not more than the predetermined current value and not less than a second predetermined current value lower than the predetermined current value.

  According to the second aspect of the present invention, since the current value can be kept within a predetermined range, it is possible to detect the full charge capacity of the battery with higher accuracy.

In the invention according to claim 3, the full charge capacity is corrected by CAPA (n) = W × CAPA (n−1) + (1−W) × (ΔAh / ΔSOC). .
Here, CAPA (n) is a current value of the full charge capacity, CAPA (n−1) is a previous value of the full charge capacity, and W is a weighting coefficient that takes a value of 0 ≦ W ≦ 1.

  According to the third aspect of the present invention, it is possible to prevent a sudden change in the calculated full charge capacity due to a sensor error or the like.

In the invention according to claim 4, the full charge capacity calculated by CAPA (n) = W × CAPA (n−1) + (1−W) × (ΔAh / ΔSOC) is CAPAF (n) = It is corrected by F × CAPA (n) + (1−F) × CAPAF (n−1).
Here, CAPAF (n) is the current value of the full charge capacity filter value, CAPAF (n−1) is the previous value of the full charge capacity filter value, and F is a filter coefficient that takes a value of 0 ≦ F ≦ 1.

  According to the invention which concerns on Claim 4, the rapid change of the full charge capacity of a battery can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the battery capacity detection method which enables the full charge capacity of a highly accurate battery can be provided.

It is a block diagram which shows the structural example of the battery capacity calculation apparatus which concerns on this embodiment. It is a block diagram for determining conditions Z1 and conditions Z2 concerning this embodiment. It is a block diagram for determining condition Z3 concerning this embodiment. It is a block diagram for determining condition Z4 concerning this embodiment. It is a block diagram for determining condition Z5 concerning this embodiment. It is a flowchart which shows the flow of an equivalent circuit model calculation process. It is a flowchart which shows the flow of the timing condition determination process which concerns on this embodiment. It is a flowchart which shows the flow of the battery capacity calculation process which concerns on this embodiment (the 1). It is a flowchart which shows the flow of the battery capacity calculation process which concerns on this embodiment (the 2).

  Next, the best mode for carrying out the present invention (referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate.

(Battery capacity calculation device)
FIG. 1 is a block diagram illustrating a configuration example of the battery capacity calculation apparatus according to the present embodiment.
The battery capacity calculation device (battery capacity detection device) 1 includes an equivalent circuit model calculation unit 10, a timing condition determination unit 20, a battery capacity calculation unit 30, and a storage unit 40.
The equivalent circuit model calculation unit 10 includes each of an actual voltage value, an actual current value, and a battery temperature obtained from a voltage sensor 60, a current sensor 70, and a temperature sensor 80 installed in a battery (battery) (not shown) mounted on the vehicle. Sensor values are input, and an estimated SOC value based on the equivalent circuit model method is calculated from these values, and the calculated estimated SOC value is output to the battery capacity calculation unit 30.

  The timing condition determination unit 20 includes an actual voltage value, an actual current value, a battery temperature, and a stable current value map 41 and a stable current fluctuation value map 42 that are stored in the storage unit 40. Using the stable voltage fluctuation value map 43 and the reference resistance value map 44, it is determined whether or not all of the following five conditions (timing conditions) are satisfied, and the switch flag is calculated based on the determination result. The function of outputting to the unit 30 is provided.

Condition Z1: Less than the difference value threshold (predetermined error) between the estimated value of the voltage fluctuation value estimated by the equivalent circuit model method and the actual voltage fluctuation value input from the voltage sensor 60 Condition Z2: input from the current sensor 70 The actual current value is less than or equal to a predetermined upper limit value (predetermined current value), or the actual current value is within a predetermined range (greater than or equal to a predetermined lower limit current value and less than or equal to a predetermined upper limit current value). Condition Z3: Condition Z4 below predetermined value (predetermined current fluctuation value): Actual voltage fluctuation value within predetermined period is below predetermined value (predetermined voltage fluctuation value) Condition Z5: Battery temperature input from temperature sensor 80 is a threshold (predetermined battery) Temperature) or more

When the battery capacity calculation unit 30 detects that the timing conditions Z1 to Z5 are satisfied, the battery capacity calculation unit 30 calculates the battery capacity based on the estimated SOC value using the equivalent circuit model as the first timing or the second timing. It has a function. The battery capacity calculation unit 30 calculates the battery capacity when the following conditions (capacity calculation conditions) W1 to W4 are satisfied in addition to the conditions Z1 to Z5 being satisfied.
Condition W1: The SOC fluctuation value (ΔSOC) at the first timing and the second timing is equal to or greater than a predetermined value (a condition for not reducing the denominator in the second term of Equation (5) described later).
Condition W2: When the actual current value (ΔAh = | ΣI |) integrated between the first timing and the second timing is equal to or larger than a predetermined value (for example, ΔAh is a value close to 0, the following formula (5 The condition for avoiding that the current value of the battery capacity calculated in the second term of) is close to 0)
Condition W3: The interval between the first timing and the second timing is not less than the predetermined time T1 and not more than the predetermined time T2 (in order to prevent the battery capacity from being calculated in a short time, the actual current value is (Conditions for avoiding the error of ΔAh caused by integration)
Condition W4: ΔSOC and the sign of ΔAh have the same sign (since ΔSOC and ΔAh, which should be the same sign originally, have different signs, it is considered that an error such as current sensor 70 has occurred)

  When these conditions W1 to W4 are satisfied, the battery capacity calculation unit 30 calculates the battery capacity using the weighting coefficient and the filter coefficient. A method for calculating the battery capacity (battery full charge capacity) using the weight coefficient and the filter coefficient will be described later.

The equivalent circuit model calculation unit 10 includes a voltage / current fluctuation value calculation unit 11, an RLS (Recursive Least Square) identification unit 12, an OCV estimation unit 13, and an SOC conversion unit 14.
The voltage / current fluctuation value calculation unit 11 calculates the actual voltage fluctuation value and the actual current fluctuation from the input actual voltage value and actual current value, and the previous actual voltage value and the previous actual current value temporarily stored in the storage unit 40. It has a function to calculate a value.
Based on the actual voltage fluctuation value and the actual current fluctuation value input from the voltage / current fluctuation value calculation unit 11 and the battery temperature input from the temperature sensor 80, the RLS identification unit 12 uses a sequential least squares method to determine the inside of the battery. It has a function of estimating the resistance value.
The OCV estimation unit 13 has a function of estimating the OCV based on the internal resistance value input from the RLS identification unit 12.
And the SOC conversion part 14 has a function which estimates SOC by an equivalent circuit model system from OCV using the OCV-SOC map which is not illustrated.
The equivalent circuit model calculation unit 10 is a known technique (see, for example, Japanese Patent Application Laid-Open No. 2009-103471).

The storage unit 40 stores a stable current value map 41, a stable current fluctuation value map 42, a stable voltage fluctuation value map 43, and a reference resistance value map 44, which will be described later. Instead of the stable current value map 41, the stable current fluctuation value map 42, the stable voltage fluctuation value map 43, and the reference resistance value map 44, functions corresponding to the maps 41 to 44 may be stored.
The battery capacity calculation device 1 is mounted on an ECU (Electronic Control Unit) or the like, and is used in an equivalent circuit model calculation unit 10, a timing condition determination unit 20, a battery capacity calculation unit 30, and an equivalent circuit model calculation unit 10. The units 11 to 14 are realized by a program stored in a ROM (Read Only Memory) or the like being executed by a CPU (Central Processing Unit).

  Next, processing for determining the conditions Z1 to Z5 for detecting the first timing and the second timing will be described with reference to FIGS.

(Condition Z1: The difference value between the estimated voltage value and the actual voltage value is a predetermined value or less)
FIG. 2A is a block diagram for determining the condition Z1 according to the present embodiment.
The condition Z1 is that when the error between the actual voltage fluctuation value and the voltage fluctuation value estimated using the equivalent circuit model is large, the modeling error of the equivalent circuit model method is large, so that the first calculation for calculating the battery capacity is performed. This is a condition for avoiding the timing 1 and the second timing.
First, the timing condition determination unit 20 subtracts the actual voltage value temporarily stored in the storage unit 40 and the previous value of the actual current value from the actual voltage value and actual current value input from the voltage sensor 60 and current sensor 70. Thus, the actual voltage fluctuation value and the actual current fluctuation value are calculated. Then, the timing condition determination unit 20 calculates the estimated value of the voltage fluctuation value by multiplying the actual current fluctuation value by the estimated value of the internal resistance value calculated by the equivalent circuit model calculation unit 10 (S101).

Next, the timing condition determination unit 20 calculates the difference value of the voltage fluctuation value by subtracting the estimated value of the voltage fluctuation value from the actual voltage fluctuation value (S102).
Then, the timing condition determination unit 20 compares a preset threshold value (predetermined error) with the difference value calculated in step S102 (S103), and outputs a comparison result. For example, the timing condition determination unit 20 outputs “1” as a comparison result if the difference value is less than or equal to the threshold value, and outputs “0” if the difference value is greater than the threshold value.
Note that the threshold value may be 1 mV, for example.

(Condition Z2: The actual current value input from the current sensor 70 is equal to or less than a predetermined value, or the actual current value is within a predetermined range)
FIG. 2B is a block diagram for determining the condition Z2 according to the present embodiment.
The condition Z2 is that when a large current flows or when the actual current value is small, the modeling error of the equivalent circuit model method is large, so the first timing and the second timing for calculating the battery capacity are This is a condition for not. The time when a large current flows is when the power supplied from the battery to the motor is large during vehicle acceleration, or when the amount of regenerative power from the motor to the battery is large during vehicle deceleration.
First, the timing condition determination unit 20 calculates a stable current value at the input battery temperature from the stable current value map 41 stored in the storage unit 40 based on the battery temperature input from the temperature sensor 80 ( S201). As shown in FIG. 2B, the stable current value map 41 is a map in which the battery temperature (T [° C.]) and the stable current value (I [A]) are associated with each other.
Then, the timing condition determination unit 20 calculates the absolute value of the actual current value (S202), compares this absolute value with the stable current value (predetermined current value) calculated in step S201 (S203), and compares the result. Is output. The reason why the absolute value is calculated in step S202 is to consider that the sign of the current changes between the charging direction and the discharging direction. For example, the timing condition determination unit 20 outputs “1” as a comparison result if the absolute value is less than or equal to the stable current value, and outputs “0” if the absolute value is greater than the stable current value.

In FIG. 2B, “1” is output if the absolute value in step S202 is equal to or less than the stable current value. However, the timing condition determination unit 20 determines that the absolute value of the actual current value is within a predetermined range in the following procedure. It may be determined that it is within. That is, the battery capacity calculation device 1 stores the maximum stable current value map and the minimum stable current value map in the storage unit 40, and the timing condition determination unit 20 determines the maximum stable current value map, the minimum stable current based on the battery temperature. A maximum stable current value (predetermined upper limit current value) and a minimum stable current value (predetermined lower limit current value) are calculated from the value map. The timing condition determination unit 20 outputs “1” if the absolute value of the actual current value is within the range of the highest stable current value and the lowest stable current value, and the absolute value is the highest stable current value and the lowest stable current value. If it is out of the range, “0” is output.
Furthermore, the timing condition determination unit 20 outputs “1” if the absolute value is 30 [A] or less, or outputs “1” if the absolute value is 3 [A] or more and 30 [A] or less. For example, the determination may be made with a constant value without using a map.

(Condition Z3: Actual current fluctuation value within a predetermined period is not more than a predetermined value)
FIG. 3 is a block diagram for determining the condition Z3 according to the present embodiment.
The condition Z3 is a condition for avoiding the first timing and the second timing for calculating the battery capacity because the modeling error of the equivalent circuit model method is large when the fluctuation of the actual current value is large. .
First, the timing condition determination unit 20 acquires an actual current value that is set in advance and is temporarily stored in the storage unit 40 before a predetermined time ΔT1 (S301). Is subtracted (S302) to calculate the actual current fluctuation value ΔI0 within a predetermined period. For example, 1 second is set as the predetermined time ΔT1.
On the other hand, the timing condition determination unit 20 calculates a stable current fluctuation value at the battery temperature from the battery temperature input from the temperature sensor 80 and the stable current fluctuation value map 42 stored in the storage unit 40 (S303). . As illustrated in FIG. 3, the stable current fluctuation value map 42 is a map in which the battery temperature (T [° C.]) and the stable current fluctuation value (ΔI [A]) are associated with each other.

Then, the timing condition determining unit 20 compares the actual current fluctuation value (ΔI0) within the predetermined period with the stable current fluctuation value (ΔI: predetermined current fluctuation value) (S304), and outputs the comparison result. For example, if the actual current fluctuation value is equal to or less than the stable current fluctuation value, the timing condition determination unit 20 outputs “1” as the comparison result, and if the actual current fluctuation value is larger than the stable current fluctuation value, "0" is output.
Note that if the actual current fluctuation value is 10 [A] or less, the timing condition determination unit 20 may perform comparison using a constant without using a map, such as outputting “1” as a comparison result.

(Condition Z4: Actual voltage fluctuation value within a predetermined period is not more than a predetermined value)
FIG. 4 is a block diagram for determining the condition Z4 according to the present embodiment.
The condition Z4 is a condition for avoiding the first timing and the second timing for calculating the battery capacity because the modeling error of the equivalent circuit model method is large when the fluctuation of the actual voltage value is large. .
First, the timing condition determination unit 20 obtains an actual voltage value that is set in advance and is temporarily stored in the storage unit 40 before the predetermined time ΔT2 (S401), and is acquired from the current value of the actual voltage value by a predetermined time before. The actual voltage value is subtracted (S402) to calculate the actual voltage fluctuation value ΔV0 within a predetermined period. The predetermined time ΔT2 is set to 1 second, for example.
On the other hand, the timing condition determination unit 20 acquires a stable voltage value fluctuation value from the battery temperature input from the temperature sensor 80 and the stable voltage fluctuation value map 43 stored in the storage unit 40 (S403). As shown in FIG. 4, the stable voltage fluctuation value map 43 is a map in which the battery temperature (T [° C.]) is associated with the stable voltage fluctuation value (ΔV [V]).

Further, the timing condition determination unit 20 calculates the reference resistance value R0 from the input battery temperature and the reference resistance value map 44 stored in the storage unit 40 (S404). The reference resistance value is, for example, an internal resistance value under a corresponding battery temperature in a new battery. As shown in FIG. 4, the reference resistance value map 44 is a map in which the battery temperature (T [° C.]) and the reference resistance value (R0 [mΩ]) are associated with each other.
Then, the timing condition determination unit 20 divides the estimated internal resistance value R calculated by the equivalent circuit model by R0 calculated in step S404 (S405), and calculates the calculated R / R0 to the stable voltage fluctuation value calculated in step S403. Multiply (S406). This is a process performed in order to consider the influence of the internal resistance value accompanying the deterioration of the battery.

Finally, the timing condition determination unit 20 compares the actual voltage fluctuation value (ΔV0) within the predetermined period calculated in step S402 with the stable voltage fluctuation value (predetermined voltage fluctuation value) multiplied by R / R0 in step S406. (S407), the comparison result is output.
For example, the timing condition determination unit 20 outputs “1” as a comparison result if the actual voltage fluctuation value is less than or equal to the stable voltage fluctuation value, and outputs “0” if the actual voltage fluctuation value is greater than the stable voltage fluctuation value. To do.
If the actual voltage fluctuation value is 0.1 [V] or less, the timing condition determination unit 20 may use a constant without using a map, such as outputting “1” as a comparison result.

(Condition Z5: Battery temperature is a predetermined value or more)
FIG. 5 is a block diagram for determining the condition Z5 according to the present embodiment.
In the condition Z5, since the internal resistance value of the battery becomes large under extremely low temperature conditions, the modeling error of the equivalent circuit model method becomes large under such extremely low temperature conditions, so the first timing for calculating the battery capacity This is a condition for avoiding the second timing.
The timing condition determination unit 20 compares the battery temperature input from the temperature sensor 80 with a preset threshold value (predetermined battery temperature) (S501), and outputs the comparison result.
For example, the timing condition determination unit 20 outputs “1” if the battery temperature is higher than the threshold value, and outputs “0” if the battery temperature is equal to or lower than the threshold value.
As the threshold value, for example, “−30 [° C.]” can be considered.

(Equivalent circuit model calculation processing)
Next, an equivalent circuit model calculation process, a timing condition determination process, and a battery capacity calculation process will be described with reference to FIGS.
FIG. 6 is a flowchart showing the flow of the equivalent circuit model calculation process. The equivalent circuit model calculation process shown in FIG. 6 is a known process as described above. The equivalent circuit model calculation processing is a technique described in Japanese Patent Application Laid-Open No. 2009-103471.
First, the current value of the actual voltage value is V (k), the current value of the actual current is I (k), the previous value of the actual voltage value is V (k−1), and the previous value of the actual current value is I (k− 1) When the actual current fluctuation value is dV (k) and the actual current fluctuation value is dI (k), the voltage / current fluctuation value calculation unit 11 calculates the following expressions (1) and (2). Thus, the actual voltage fluctuation value (dV (k)) and the actual current fluctuation value ((dI (k))) are calculated (S601).

dV (k) = V (k) −V (k−1) (1)
dI (k) = I (k) -I (k-1) (2)

Next, the RLS identification unit 12 calculates an estimated value of the internal resistance value R by the successive least square method from the actual voltage fluctuation value (dV (k)) and the actual current fluctuation value (dI (k)) calculated in step S601. Calculate (S602).
Then, the OCV estimation unit 13 calculates an estimated value OCV (k) of the open circuit voltage value of the battery based on the estimated internal resistance value (S603).
Then, the SOC conversion unit 14 calculates the estimated value SOC (k) of the state of charge based on the equivalent circuit model based on the estimated value OCV (k) of the open circuit voltage value calculated in step S603 (S604).
The estimated state of charge SOC (k) calculated in step S604 is output to the battery capacity calculation unit 30, and the equivalent circuit model calculation unit 10 returns to step S601.

(Timing condition judgment processing)
FIG. 7 is a flowchart showing a flow of timing condition determination processing according to the present embodiment.
First, the timing condition determination unit 20 receives the actual voltage fluctuation value (dV (k)), the actual current fluctuation value (dI (k)), and the estimated value (R) of the internal resistance of the battery from the equivalent circuit model calculation unit 10. 2 is performed, it is determined whether or not the condition Z1 is satisfied, that is, whether or not the inequality of Expression (3) is satisfied (S701). Note that the threshold in equation (4) is a predetermined error.

| DV (k) −dI (k) × R | ≦ threshold value (3)

  As a result of step S701, when the inequality of the expression (3) is not satisfied (S701 → No: the condition Z1 is not satisfied: the comparison result of FIG. 2A corresponds to “0”), the timing condition determination unit 20 determines the timing. The flag is set to “0” (S707), output to the battery capacity calculation unit 30, and the process returns to step S701.

As a result of Step S701, when the inequality of Expression (3) is satisfied (S701 → Yes: Condition Z1 is satisfied: the comparison result of FIG. 2A corresponds to “1”), the timing condition determination unit 20 By performing the processing described with reference to FIG. 2B, the condition Z2 indicates that the absolute value (| I |) of the actual current value is the predetermined lower limit value (the lowest stable current value in FIG. 2B: the predetermined lower limit current value). As described above, it is determined whether or not it is equal to or less than the predetermined upper limit value (the maximum stable current value in FIG. 2B: the predetermined upper limit current value) (S702).
Note that the processing in step S702 is to determine whether or not the absolute value of the actual current value is within a predetermined range in FIG. 2B. In step S702, the timing condition determining unit 20 determines the actual current value. It may be determined whether or not the absolute value of the value is equal to or less than a predetermined value (predetermined current value).
As a result of step S702, when the absolute value of the actual current value is larger than the predetermined upper limit value or smaller than the predetermined lower limit value (S702 → No: Condition Z2 is not satisfied: the comparison result in FIG. 2B corresponds to “0”) ), The timing condition determination unit 20 sets the timing flag to “0” (S707), outputs the timing flag to the battery capacity calculation unit 30, and returns to step S701.

As a result of step S702, when the absolute value of the actual current value is not more than the predetermined upper limit value and not less than the predetermined lower limit value (S702 → Yes: Condition Z2 is satisfied: the comparison result in FIG. 2B corresponds to “1”). The timing condition determination unit 20 performs the processing described with reference to FIG. 3 to determine whether or not the condition Z3 is satisfied, that is, the actual current fluctuation value (ΔI0) within a predetermined period is a predetermined value (stable current fluctuation value ΔI in FIG. 3). : Predetermined current fluctuation value) or less (S703).
As a result of step S703, when the actual current fluctuation value (ΔI0) within the predetermined period is larger than the predetermined value (S703 → No: Condition Z3 is not satisfied: the comparison result in FIG. 3 is equivalent to “0”), the timing condition determination unit 20 determines the timing. The flag is set to “0” (S707), output to the battery capacity calculation unit 30, and the process returns to step S701.

As a result of step S703, when the actual current fluctuation value (ΔI0) within the predetermined period is equal to or less than the predetermined value (S703 → Yes: Condition Z3 is satisfied: the comparison result in FIG. 3 corresponds to “1”), the timing condition determination unit 20 4, whether or not the condition Z4 is satisfied, that is, the actual voltage fluctuation value (ΔV0) within a predetermined period is a predetermined value (stable voltage fluctuation value ΔV in FIG. 4: predetermined voltage fluctuation value). It is determined whether or not (S704).
As a result of step S704, when the actual voltage fluctuation value (ΔV0) within the predetermined period is larger than the predetermined value (S704 → No: Condition Z4 is not satisfied: the comparison result in FIG. 4 is equivalent to “0”), the timing condition determination unit 20 determines the timing. The flag is set to “0” (S707), output to the battery capacity calculation unit 30, and the process returns to step S701.

As a result of step S704, when the actual voltage fluctuation value (ΔV0) within the predetermined period is equal to or smaller than the predetermined value (S704 → Yes: Condition Z4 is satisfied: the comparison result in FIG. 4 is equivalent to “1”), the timing condition determination unit 20 By performing the processing described with reference to FIG. 5, it is determined whether or not the condition Z5 is satisfied, that is, whether or not the battery temperature T is equal to or higher than the threshold (S705).
When the battery temperature T is lower than the threshold value (predetermined battery temperature) as a result of step S705 (S705 → No: Condition Z5 is not established: the comparison result in FIG. 5 is equivalent to “0”), the timing condition determination unit 20 determines the timing. The flag is set to “0” (S707), output to the battery capacity calculation unit 30, and the process returns to step S701.

  As a result of step S705, when the battery temperature T is equal to or higher than the threshold (S705 → Yes: Condition Z5 is satisfied: the comparison result in FIG. 5 corresponds to “1”), the timing condition determination unit 20 sets the timing flag to “1”. (S706), it outputs to the battery capacity calculation part 30, and returns to step S701.

  In this embodiment, the timing flag is set to “1” when all of the conditions Z1 to Z5 are satisfied. However, the timing flag may be set to “1” when at least the condition Z1 is satisfied.

(Battery capacity calculation processing)
8 and 9 are flowcharts showing the flow of the battery capacity calculation process according to the present embodiment.
First, the battery capacity calculation unit 30 determines whether or not the conditions Z1 to Z5 are satisfied by determining whether or not the timing flag acquired from the timing condition determination unit 20 is “1” (S801 in FIG. 8). Determine. Note that “Yes” may be determined only when all of the conditions Z1 to Z5 are satisfied, or “Yes” may be determined at least when the condition Z1 is satisfied. Here, the timing at which the previous SOC detection condition is satisfied becomes the first detection timing, and the timing at which the current SOC detection condition is satisfied becomes the second detection timing.
As a result of step S801, when the timing flag is “1” (S801 → Yes), the battery capacity calculation unit 30 acquires the estimated SOC value by the equivalent circuit model method from the equivalent circuit model calculation unit 10 (S802).
Then, the battery capacity calculation unit 30 subtracts the previous value (SOCP) of the SOC estimated value temporarily stored in the storage unit from the SOC estimated value (SOC) acquired in step S802 (| SOC− It is determined whether SOCP |) is equal to or greater than a predetermined value (S803: Condition W1). As the predetermined value in step S803, 5 (%) or the like can be considered.

If the result of step S803 is equal to or greater than the predetermined value (S803 → Yes: condition W1 is satisfied), the battery capacity calculator 30 calculates the absolute value (| ΣI |) of the value obtained by integrating the actual current value in step S808 described later. It is determined whether or not the value is equal to or greater than a predetermined value (S804: Condition W2). As the predetermined value in step S804, 0.1 (Ah) can be considered.
If the result of step S804 is equal to or greater than the predetermined value (S804 → Yes: condition W2 is satisfied), battery capacity calculation unit 30 determines whether elapsed time T since the last SOC detection condition is satisfied is equal to or greater than predetermined time T1. (S805: lower limit condition of condition W3). In addition, as T1, 10 (sec) etc. can be considered.

As a result of step S805, when the elapsed time T is equal to or longer than the predetermined time T1 (S805 → Yes: the condition W3 is adjusted), the battery capacity calculation unit 30 calculates the SOC estimated value from the current value (SOC) of the SOC estimated value. The value obtained by subtracting the previous value (SOCP) of the battery is ΔSOC (rate of change of the remaining battery capacity) (ΔSOC = SOC−SOCP), and the absolute value of the integrated value of the actual current value is ΔAh (battery capacity change value). (ΔAh = ΣI), the counter CNT is incremented by 1 (CNT = CNT + 1) (S806).
Thereafter, the battery capacity calculation unit 30 updates the previous SOC value (SOCP) with the current value (SOC) (SOCP = SOC), updates the integrated value of the actual current value to “0” (ΣI = 0), and elapses. The time T is updated to “0” (T = 0) (S807), and the process proceeds to step S809.

  On the other hand, when “No” is determined in any of steps S801, S803, S804, and S805 (that is, when any of the conditions W1 to W3 is not established), the battery capacity calculation unit 30 acquires the current from the current sensor. Using the actual current value I, the current integrated value ΣI is updated according to the following equation (4), the elapsed time T is updated by adding the calculation period Tsample to the elapsed time T (T = T + Tsample) (S808), and step S809. Proceed to the process.

ΣI = ΣI + I / (3600 × Tsample) (4)

After step S807 and step S808, the battery capacity calculation unit 30 determines whether or not an elapsed time T since the previous SOC detection condition is satisfied is equal to or less than a predetermined time T2 (S809 in FIG. 9: condition W3). Upper limit condition). In addition, 120 (sec) etc. can be considered as T2.
As a result of step S809, when the elapsed time T is equal to or shorter than the predetermined time T2 (S809 → Yes: the upper limit condition of the condition W3 is satisfied), the battery capacity calculation unit 30 determines whether ΔSOC × ΔAh is a positive value. A determination is made (S810), and it is determined whether ΔSOC and ΔAh have the same sign (condition W4).
When ΔSOC × ΔAh is a positive value in step S810 (S810 → Yes: Condition W4 is satisfied), the battery capacity calculation unit 30 determines whether or not the counter CNT is larger than the battery capacity calculation condition satisfaction count ESTN. Determination is made (S811). The process of step S811 is for calculating the battery capacity in step S812 only when step S806 has elapsed, that is, only when the lower limit conditions of the conditions W1 and W2 and the condition W3 are satisfied.

  In step S811, when the counter CNT is larger than the number of times the battery capacity calculation condition is established ESTN (S811 → Yes), the battery capacity calculation unit 30 sets the previous value CAPA of the battery capacity or a preset weight coefficient W (0 ≦ W ≦ 1) or the like is used to update the battery capacity from Equation (5), and the battery capacity calculation condition establishment count ESTN is updated with the counter CNT (S812). When the battery capacity calculation unit 30 calculates Expression (5), it is possible to prevent a sudden change in the calculated battery capacity due to a sensor error or the like.

CAPA = W × CAPA + (1−W) × (ΔAh / ΔSOC) (5)

In step S812, the current value of the battery capacity may be calculated like a moving average using the battery capacity of the past n times.
In step S812, the battery capacity CAPA may be calculated from the following equation (6) without using a weighting factor.

CAPA = ΔAh / ΔSOC (6)

  Then, the battery capacity calculation unit 30 uses the battery capacity CAPA updated in step S812, the last battery capacity CAPAF of the previous time, and a preset filter coefficient F (0 ≦ F ≦ 1). Then, the final battery capacity CAPAF is updated (S813), and the process returns to step S801. Step S813 is a filter calculation performed to prevent the final battery capacity from changing suddenly.

CAPAF = F × CAPA + (1−F) × CAPAF (7)

  When “No” is determined in step S809 and step S810 (the upper limit condition of condition W3 or W4 is not established) or “No” is determined in step S811, battery capacity calculation unit 30 skips step S812 and performs step S813. Process. That is, the process of step S813 is performed without updating the value of the battery capacity CAPA.

  Note that all of the conditions W1 to W4 do not need to be satisfied, and it is sufficient that at least the upper limit condition and the condition W4 of the condition W3 are satisfied. In other words, at least steps S801, S806, S807, S808, S810, and S812 need only be executed in FIG.

(Summary)
According to the present embodiment, the battery capacity can be calculated using the estimated SOC value by the equivalent circuit model method without using the current integration method in which the error of the current sensor 70 is accumulated. At this time, the timings avoiding the conditions Z1 to Z5 that cause a large error in the equivalent circuit model method can be set as the first timing and the second timing for calculating the battery capacity. Calculation is possible.
Therefore, it is possible to calculate the battery capacity with high accuracy using an equivalent circuit model that can follow changes in battery characteristics.

1 Battery capacity calculation device (battery capacity detection device)
DESCRIPTION OF SYMBOLS 10 Equivalent circuit model calculation part 11 Voltage / current fluctuation value calculation part 12 RLS identification part 13 OCV estimation part 14 SOC conversion part 20 Timing condition determination part 30 Battery capacity calculation part 40 Storage part 41 Stable current value map 42 Stable current fluctuation value map 43 Stable voltage fluctuation map 44 Reference resistance value map 60 Voltage sensor 70 Current sensor 80 Temperature sensor

Claims (4)

The full charge capacity of the battery according to the equation (1) from the battery capacity change value between the first detection timing and the second detection timing and the rate of change of the remaining battery capacity calculated by the equivalent circuit model method A battery capacity detection method by a battery capacity detection device for detecting
The first detection timing and the second detection timing are:
The error between the estimated voltage value based on the equivalent circuit model and the actual voltage value obtained from the voltage sensor is less than or equal to a predetermined error,
The actual current value obtained from the current sensor is less than or equal to a predetermined current value,
The actual current fluctuation value within the predetermined period is less than or equal to the predetermined current fluctuation value,
The actual voltage fluctuation value within the predetermined period is less than or equal to the predetermined voltage fluctuation value,
A battery capacity detection method, wherein the battery temperature acquired from the temperature sensor is equal to or higher than a predetermined battery temperature.
CAPA = ΔAh / ΔSOC (1)
However, CAPA is the full charge capacity of the battery, ΔAh is the capacity change value of the battery between the first detection timing and the second detection timing, and ΔSOC is the first detection timing. The change rate of the remaining capacity of the battery calculated by the equivalent circuit model method between the second detection timing and the second detection timing. 2. The battery capacity detection method according to claim 1, wherein the predetermined current value is equal to or lower than the predetermined current value and equal to or higher than a second predetermined current value lower than the predetermined current value. The battery capacity detection method according to claim 1, wherein the full charge capacity is corrected by Equation (2).
CAPA (n) = W × CAPA (n−1) + (1−W) × (ΔAh / ΔSOC) (2)
Here, CAPA (n) is a current value of the full charge capacity, CAPA (n−1) is a previous value of the full charge capacity, and W is a weighting coefficient that takes a value of 0 ≦ W ≦ 1. The battery capacity detection method according to claim 3, wherein the full charge capacity calculated by the equation (2) is corrected by the equation (3).
CAPAF (n) = F * CAPA (n) + (1-F) * CAPAF (n-1) (3)
Here, CAPAF (n) is the current value of the full charge capacity filter value, CAPAF (n−1) is the previous value of the full charge capacity filter value, and F is a filter coefficient that takes a value of 0 ≦ F ≦ 1.

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