WO2018186088A1

WO2018186088A1 - Battery control device

Info

Publication number: WO2018186088A1
Application number: PCT/JP2018/008461
Authority: WO
Inventors: 大川　圭一朗; 亮平中尾
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2017-04-07
Filing date: 2018-03-06
Publication date: 2018-10-11
Also published as: JPWO2018186088A1; JP6827527B2

Abstract

It has conventionally been difficult to set a weighting for calculating an SOC with high accuracy. This battery control device has a weighting factor computation unit 114 that calculates a weighting factor W on the basis of a formula (5) so that an SOCv specific gravity and SOCi specific gravity are automatically selected in accordance with the magnitude of a current I. Formula (5): W=1/{(1+|I|×R×G2)×G1} Herein, the correction factor G1 is set to a value 1 or greater and a value not greater than a prescribed value such as, for example, 100 in the present embodiment and subsequent embodiments. The correction factor G2 is set to a value 0 or greater. For the correction factors G1 and G2, values corresponding to a characteristic of a battery 400 are stored in advance in a storage unit 120. It suffices for the value of the correction factor G1 to be a value not greater than a prescribed value such as, for example, 100.

Description

Battery control device

The present invention relates to a battery control device.

Examples of devices using batteries such as lithium secondary batteries, nickel hydride batteries, lead batteries, and electric double layer capacitors include battery systems, distributed power storage devices, and electric vehicles. In these devices, in order to use the battery safely and effectively, a battery state detection device for detecting the state of the battery is used. As the state of the battery, the state of charge (State 程度 of Charge: hereinafter referred to as SOC) indicating how much the battery has been charged or how much charge can be discharged remains. There is a health state (State of Health: hereinafter referred to as SOH).

The SOC in a battery system such as an electric vehicle is calculated by calculating the ratio of the amount of charge remaining in the battery (remaining capacity) to the amount of charge (total capacity) that can be fully charged by integrating the discharge current from full charge. Can be obtained. The SOC thus determined is referred to as SOCi. In addition to the SOCi, the relationship between the voltage across the battery (open circuit voltage) and the remaining capacity of the battery is defined in advance in a data table or the like, and the current remaining capacity can be calculated by referring to this. it can. The SOC thus obtained is referred to as SOCv. Furthermore, the state of charge can also be obtained by combining these methods. For example, Patent Document 1 describes that when SOCi and SOCv are combined, they are weighted and added according to the battery temperature.

JP 2014-44074 A

When the method described in Patent Document 1 described above is used, it is difficult to set weights for calculating the SOC with high accuracy.

The battery control device according to the present invention includes an SOCv calculation unit that calculates the state of charge of the battery using a voltage across the battery, and an SOCi calculation unit that calculates the state of charge of the battery by integrating the current I flowing through the battery. A weighting factor calculation for calculating a weighting factor W based on a calculation formula including an absolute value of the magnitude of the current I, an internal resistance R of the battery, a first factor G1, and a second factor G2. And a SOCw calculation unit that weights and adds the state of charge of the battery calculated by the SOCv calculation unit and the state of charge of the battery calculated by the SOCi calculation unit using the weighting factor W,
The first coefficient G1 of the calculation formula is related to the whole calculation formula, and the second coefficient G2 is related to the absolute value of the magnitude of the current I in the calculation formula.

According to the present invention, it is easy to set a weight for calculating the SOC with high accuracy.

It is a block block diagram of a battery system. It is a functional block diagram which shows the detail of a battery state estimation apparatus. It is a figure which shows the equivalent circuit of a battery. It is a figure which shows the relationship between OCV and SOC. It is a figure which shows the relationship between the internal resistance of a battery, and battery temperature. It is a figure which shows the table of the correction coefficient G2 in 2nd Embodiment. It is a figure which shows the table of the correction coefficient G2 in 3rd Embodiment. It is a figure which shows the table of the correction coefficient G2 in 4th Embodiment. It is a figure which shows the summary of each embodiment.

-First embodiment-
FIG. 1 is a block configuration diagram of a battery system 1000 according to the first embodiment. The battery system 1000 includes a battery 400, a measurement unit 200, a battery control device 100, and an output unit 300, and supplies the electric charge accumulated in the battery 400 from the output unit 300 as electric power. As an object to which the battery system 1000 supplies power, for example, an electric vehicle, a hybrid vehicle, a train, and the like can be considered.

The battery 400 is a rechargeable battery such as a lithium ion secondary battery. In addition, the present embodiment can be applied to devices having a power storage function such as a nickel metal hydride battery, a lead battery, and an electric double layer capacitor. The battery 400 may be a single battery cell or a module structure in which a plurality of single battery cells are combined.

The measuring unit 200 is a functional unit that measures the physical characteristics of the battery 400, for example, the voltage V across the battery 400, the current (battery current) I flowing through the battery 400, the battery temperature T of the battery 400, and the like. It is composed of sensors and necessary electrical circuits.

The output unit 300 is a functional unit that outputs the output of the battery control device 100 to an external device (for example, a host device such as a vehicle control device provided in an electric vehicle).

The battery control device 100 is a device that controls the operation of the battery 400, and includes a battery state estimation device 110 and a storage unit 120. As will be described later, the battery state estimation requires the internal resistance R of the battery 400, but in the present embodiment, the battery state estimation device 110 uses other measurement parameters to calculate.

The battery state estimation device 110 includes the battery 400 stored in the storage unit 120 based on the voltage V across the battery 400 measured by the measurement unit 200, the battery current I flowing through the battery 400, and the battery temperature T of the battery 400. The SOC of the battery 400 is calculated with reference to the characteristic information. Details of the SOC calculation method will be described later.

The storage unit 120 stores the characteristic information of the battery 400 that can be known in advance such as the internal resistance R and the polarization voltage Vp of the battery 400 according to the battery 400. Furthermore, the storage unit 120 stores a resistance table indicating the relationship between the internal resistance R of the battery 400 and the battery temperature T, an SOC table indicating the relationship between the open circuit voltage OCV and the SOC of the battery 400, and the like.

The battery control device 100 and the battery state estimation device 110 can be configured using hardware such as a circuit device that realizes the function. Moreover, it is also possible to configure the software in which the function is implemented by executing an arithmetic device such as a CPU (Central Processing Unit). In the latter case, the software is stored in the storage unit 120, for example.

The storage unit 120 is configured using a storage device such as a flash memory, an EEPROM (Electrically-Erasable-Programmable-Read-Only Memory), or a magnetic disk. The storage unit 120 may be provided outside the battery state estimation device 110, or may be realized as a memory device provided inside the battery state estimation device 110. The storage unit 120 may be removable. When the storage unit 120 is removable, the characteristic information and software can be easily changed by replacing the storage unit 120. Further, by storing a plurality of storage units 120 and storing the characteristic information and software in the replaceable storage unit 120, the characteristic information and software can be updated for each small unit.

FIG. 2 is a functional block diagram showing details of the battery state estimation device 110. The battery state estimation device 110 includes an SOCv calculation unit 111, an SOCi calculation unit 112, and a weight coefficient calculation unit 114, and outputs a charge state SOCw that is a result of estimating the charge state of the battery 400. Other arithmetic units will be described later.

The SOCv calculation unit 111 calculates the SOC of the battery 400 using the voltage V across the battery 400 measured by the measurement unit 200. Hereinafter, this is referred to as SOCv. The SOCi calculation unit 112 calculates the SOC of the battery 400 by integrating the battery current I of the battery 400 measured by the measurement unit 200. Hereinafter, this is referred to as SOCi. The calculation method of SOCv and SOCi will be described later.

The weighting factor calculation unit 114 calculates a weighting factor W for weighting and adding SOCv and SOCi based on the battery current I and the battery temperature T. A method for calculating the weighting factor W will be described later.

Multiplier MP1 multiplies SOCv and weighting factor W to obtain W × SOCv. The subtractor DF obtains (1-W). Multiplier MP2 multiplies SOCi and (1-W) to obtain (1-W) × SOCi. The adder AD adds these to obtain SOCw. That is, SOCw is expressed by the following equation (1).
SOCw = W × SOCv + (1−W) × SOCi (1)

[Operation of SOCv Calculation Unit 111]
Next, the operation of the SOCv calculation unit 111 will be described. FIG. 3 is an equivalent circuit diagram of the battery 400. The battery 400 can be represented by a parallel connection pair of an impedance Z and a capacitance component C, an internal resistance R, and an open circuit voltage OCV connected in series. When the battery current I is applied to the battery 400, the closed circuit voltage CCV that is the voltage between the terminals of the battery 400 is expressed by the following equation (2). In Expression (2), Vp is a polarization voltage and corresponds to the voltage across the parallel connection pair of the impedance Z and the capacitance component C.
CCV = OCV + I · R + Vp (2)

The open circuit voltage OCV is used to calculate the SOCv, but cannot be directly measured while the battery 400 is being charged / discharged. Therefore, the SOCv calculation unit 111 obtains the open circuit voltage OCV by subtracting the IR drop and the polarization voltage Vp from the closed circuit voltage CCV as in the following equation (3).
OCV = CCV-I / R-Vp (3)

The internal resistance R and the polarization voltage Vp are stored in advance as characteristic information of the battery 400 in the storage unit 120. Since the internal resistance R and the polarization voltage Vp differ depending on the state of charge of the battery 400, the battery temperature T, and the like, individual values are stored in the storage unit 120 for each of these combinations. In the present embodiment, characteristic information that defines the correspondence between the internal resistance R and the battery temperature T is stored as a resistance table. As shown in FIG. 2, the SOCv calculation unit 111 acquires the internal resistance R from the resistance table based on the battery temperature T, and obtains an IR drop.
To do.

FIG. 4 is a diagram showing the relationship between the open circuit voltage OCV and the SOC of the battery 400. This correspondence is determined by the characteristics of the battery 400, and data defining the correspondence is stored in advance in the storage unit 120 as an SOC table. The SOCv calculator 111 calculates the open circuit voltage OCV using the above-described equation (3), and calculates the SOCv of the battery 400 by referring to the SOC table using this as a key.

[Operation of SOCi Operation Unit 112]
Next, the operation of the SOCi calculation unit 112 will be described. The SOCi calculation unit 112 calculates the SOCi of the battery 400 by accumulating the battery current I charged and discharged by the battery 400 according to the following equation (4). In Expression (4), Qmax is the full charge capacity of the battery 400 and is stored in the storage unit 120 in advance. SOCold is a value of SOCw calculated by the equation (1) in the previous calculation cycle.
SOCi = SOCold + 100 × ∫I / Qmax (4)

[Operation of Weighting Factor Calculation Unit 114]
FIG. 5 is a diagram showing the relationship between the internal resistance R of the battery 400 and the battery temperature T. In general, as shown in FIG. 5, the battery 400 has a high internal resistance R in a low SOC state and a large value of the internal resistance R in a low temperature state. Therefore, in such a case, it is considered desirable to use SOCi instead of SOCv which is easily affected by the error of the internal resistance R. Further, when the absolute value of the battery current I is small, it is influenced by a slight measurement error of the current sensor, so it is considered desirable to use SOCv instead of SOCi.

Based on the above, generally, the weighting factor calculation unit 114 calculates SOCw mainly using the SOCv when the absolute value of the battery current I is small, and mainly uses SOCi when the absolute value of the battery current I is large. The weighting factor W is set so as to calculate the SOCw. Similarly, the weighting factor W is set so that the SOCw is calculated mainly using the SOCv when the internal resistance R is small, and the SOCw is calculated mainly using the SOCi when the internal resistance R is large.

In the present embodiment, the weight coefficient calculation unit 114 calculates the weight coefficient W based on the equation (5) so that the specific gravity of SOCv and the specific gravity of SOCi are automatically selected according to the magnitude of the battery current I. .
W = 1 / {(1+ | I | × R × G2) × G1} (5)

Here, the correction coefficient G1 is a value of 1 or more in the present embodiment and the following embodiments, and is set to a value equal to or less than a predetermined value such as 100, for example. The correction coefficient G2 is set to a value of 0 or more. As the correction coefficients G 1 and G 2, values corresponding to the characteristics of the battery 400 are stored in the storage unit 120 in advance. In the present embodiment and the following embodiments, the correction coefficient G1 is assumed to be 1. However, it may be a value equal to or smaller than a predetermined value such as 100, for example. By setting the correction coefficient G1 to a value equal to or less than a predetermined value, the setting by the correction coefficient G2 can be made more effective.

According to equation (5), when G2 is set to 0 to less than 1, for example, when G2 = 0 and G1 = 1, W = 1, and from equation (1), SOCw = SOCv, and the magnitude of the current Regardless, the SOC has a high specific gravity.
Also, according to equation (5), when G2 is set to a value exceeding 1, for example, when G2 = 2 and G1 = 1, the specific gravity of SOCv and the specific gravity of SOCi are automatically set according to the magnitude of the current. Will be selected. Below, the case where the magnitude | size of an electric current is small and large is demonstrated.

(A) <When current is small>
When the magnitude of the current is small, for example, when the current is 1 A and the internal resistance is 2 mΩ, the weighting factor W is calculated from the equation (5) as follows.
W = 1 / {(1 + 1 × 2 × 2) × 1} = 1/5
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/5) × SOCv + (4/5) × SOCi

As can be seen from the SOCw equation, the SOCv is reflected by 1/5, and the specific gravity of the SOCv is larger than when the current described later is large. In this case, if the specific gravity of SOCi is large in the previous state and the SOC error is accumulated due to the current integration error based on the equation (4), the specific gravity of SOCv is large when the current is small. For this reason, the SOC error can be eliminated by the SOCv obtained using the equation (3) as a key. That is, the SOC is calibrated by the SOCv.

Further, since the current is small at this time, the error of the SOCv itself is small. The reason is as follows. The SOCv is expressed by the function f of (CCV-I × R) as in the following equation (6).
SOCv = f (CCV−I × R) (6)
Therefore, when the battery current I is very small, I × R is small, and it is difficult to be influenced by the error of the internal resistance R, and the error of the SOCv itself is also reduced. The internal resistance R of the battery takes a large value especially at a low temperature. Therefore, if there is an error such as a temperature sensor, it becomes a large error factor.

(B) <When current is large>
When the magnitude of the current is large, for example, when the current is 100 A and the internal resistance is 2 mΩ, the weighting factor W is calculated from the equation (5) as follows.
W = 1 / {(1 + 100 × 2 × 2) × 1} = 1/401
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/401) × SOCv + (400/401) × SOCi

As can be seen from the SOCw equation, SOCv is only reflected by 1/401, and the specific gravity of SOCi is larger than when the current is small. In this case, since it is hardly affected by SOCv, SOCw substantially reflects the result of SOCi. SOCi is expressed by equation (4). Since SOCi is not affected by the voltage and the internal resistance R, SOCw shows a very stable value.

As described above, when G2 is set to a value exceeding 1, the specific gravity of SOCv and the specific gravity of SOCi are automatically switched according to the magnitude of the current. When the magnitude of the current is small, the specific gravity of the SOCv is large, and the SOCv with little error is reflected in the SOCw. When the current is large, the specific gravity of SOCi increases, and SOCi that is not affected by the voltage or internal resistance R is reflected in SOCw. Even if there is an integration error due to an error of the current sensor, in a hybrid vehicle or an electric vehicle, the magnitude of the current is alternately generated with a small frequency and a large frequency, so that only when the current is large continues. In other words, the integration error is eliminated when the current decreases. Therefore, when this embodiment is used, it is possible to obtain highly accurate SOCw while automatically selecting the error calibration by SOCv and the stability by SOCi according to the magnitude of the current.

-Second Embodiment-
In the second embodiment, the block configuration diagram of the battery system of FIG. 1 described in the first embodiment, the functional block diagram showing the details of the battery state estimation device of FIG. 2, and the equivalent circuit of the battery of FIG. 3 are shown. Since the figure, the figure which shows the relationship between OCV and SOC of FIG. 4, and the figure which shows the relationship between the internal resistance of the battery of FIG. 5 and battery temperature are the same, the description is abbreviate | omitted.

FIG. 6 is a diagram showing a correction coefficient G2 table 130 in the second embodiment. The correction coefficient G2 shown in the table 130 is an example and is stored in the storage unit 120. In this table 130, the correction coefficient G2 of the range 131 in which the battery temperature T is −10 ° C. or more and 10 ° C. or less and the absolute value of the battery current I is 20 A or more is set to a value of 5 to 100, and the other ranges are corrected. The coefficient G2 is set to a value of 1. The weighting factor calculation unit 114 reads the correction factor G2 by referring to the table 130 in the storage unit 120 based on the detected battery current I and the battery temperature T, and calculates the weighting factor W based on Expression (5). To do.

When battery 400 is in a low-temperature region (for example, −10 ° C. or more and 10 ° C. or less) and has low internal resistance (for example, a negative electrode is a graphite-based battery), weighting factor W is sufficient even when the current is large. Therefore, the specific gravity of SOCi does not increase and the accuracy of SOC deteriorates. Therefore, in the present embodiment, when the battery temperature T is equal to or higher than a predetermined value and equal to or lower than the predetermined value, and the absolute value of the battery current I is equal to or higher than the predetermined value, the correction coefficient G2 is set so that the specific gravity of SOCi increases.

A case will be described in which the battery 400 is a low-temperature region (for example, −10 ° C. or more and 10 ° C. or less) and has a low internal resistance (for example, a negative electrode having a graphite-based battery) and a large battery current. For example, when the battery current I is 30 A and the battery temperature is 0 ° C., the value 50 of the correction coefficient G 2 is read from the table 130. Here, when the internal resistance = 1 mΩ and G1 = 1, the weighting coefficient W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 30 × 1 × 50) × 1} = 1/1501
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/1501) × SOCv + (1500/1501) × SOCi
As can be seen from the SOCw equation, SOCv reflects only 1/1501, and the specific gravity of SOCi is large. Therefore, SOCi improves the accuracy of the SOC.

Here, a case where G2 = 1 is described for comparison with the present embodiment. When the battery current I is 30 A and the battery temperature is 0 ° C., G2 = 1. Further, it is assumed that the internal resistance = 1 mΩ and G1 = 1. In this case, the weighting factor W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 30 × 1 × 1) × 1} = 1/31
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/31) × SOCv + (30/31) × SOCi
As can be seen from the SOCw equation, the SOCv reflects 1/31 as compared with the present embodiment, and calibration by the SOCv occurs little by little, so that the specific gravity of the SOCi does not increase and the accuracy of the SOC deteriorates.

A case will be described in which the battery 400 is a low-temperature region (for example, −10 ° C. or more and 10 ° C. or less) and a low internal resistance (for example, a negative electrode having a graphite-based battery) and a small current. For example, when the battery current I is 10 A and the battery temperature T is 0 ° C., the value 1 of the correction coefficient G 2 is read from the table 130. Here, when the internal resistance = 1 mΩ and G1 = 1, the weighting coefficient W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 10 × 1 × 1) × 1} = 1/1
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/11) × SOCv + (10/11) × SOCi
As can be seen from this SOCw equation, calibration by SOCv occurs. Thus, by setting G2 = 1 in the region where the current of the table 130 is small, calibration by SOCv can be expected by the conventional operation that is not affected by the correction coefficient G2.

According to this embodiment, even if the battery has a low low temperature region and a small internal resistance, the weighting factor W is sufficiently small when the battery current is large, the specific gravity of SOCi is large, and the accuracy of the SOC is improved. To do. When the current is small, calibration by SOCv can be expected by the conventional operation.

-Third embodiment-
In the third embodiment, the block configuration diagram of the battery system of FIG. 1 described in the first embodiment, the functional block diagram showing the details of the battery state estimation device of FIG. 2, and the equivalent circuit of the battery of FIG. 3 are shown. Since the figure, the figure which shows the relationship between OCV and SOC of FIG. 4, and the figure which shows the relationship between the internal resistance of the battery and battery temperature of FIG. 5 are the same, the description is omitted.

FIG. 7 is a view showing a correction coefficient G2 table 140 in the third embodiment. The correction coefficient G2 shown in the table 140 is an example and is stored in the storage unit 120. In this table 140, regardless of the battery temperature T, the correction coefficient G2 of the range 141 in which the absolute value of the battery current I is within 10 A is set to 0, and the correction coefficient G2 is set to 1 for the other ranges. Yes. The weighting factor calculation unit 114 reads the correction factor G2 by referring to the table 140 in the storage unit 120 based on the detected battery current I and the battery temperature T, and calculates the weighting factor W based on the equation (5). To do.

In the battery 400 having a large internal resistance as a battery characteristic, as shown in the equation (5), even when the current is small, the weighting factor W is not sufficiently increased, and the specific gravity of the SOCv is not increased, so that the SOC calibration frequency is low. For this reason, when the SOCi current accumulation error is accumulated due to the error of the current sensor, the accuracy of the SOC deteriorates due to the low calibration frequency. For this reason, in the present embodiment, when the absolute value of the battery current I is equal to or less than a predetermined value, the correction coefficient G2 is set so that the specific gravity of the SOCv is increased.

A case where the battery 400 has a large internal resistance and the battery current is small will be described. For example, when the battery current I is 10 A and the battery temperature is 25 ° C., the value 0 of the correction coefficient G 2 is read from the table 140. Here, when the internal resistance = 10 mΩ and G1 = 1, the weighting coefficient W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 10 × 10 × 0) × 1} = 1
Therefore, SOCw is as follows from the equation (1).
SOCw = 1 × SOCv + 0 × SOCi = SOCv
As can be seen from the SOCw equation, when the absolute value of the battery current I is less than or equal to a predetermined value, the specific gravity of the SOCv increases.

Here, a case where G2 = 1 is described for comparison with the present embodiment. When the battery current I is 10 A and the battery temperature is 25 ° C., G2 = 1. Further, it is assumed that the internal resistance = 10 mΩ and G1 = 1. In this case, the weighting factor W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 10 × 10 × 1) × 1} = 1/101
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/101) × SOCv + (100/101) × SOCi
As can be seen from this SOCw equation, the SOCv calibration frequency is less, the specific gravity of SOCi is greater, and the accuracy of the SOC is worse than in the present embodiment.

A case where the battery current is large in the battery 400 having a large internal resistance will be described. For example, when the battery current I is 50 A and the battery temperature is 25 ° C., the value 1 of the correction coefficient G 2 is read from the table 140. Here, when the internal resistance = 10 mΩ and G1 = 1, the weighting coefficient W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 50 × 10 × 1) × 1} = 1/501
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/501) × SOCv + (500/501) × SOCi
As can be seen from this SOCw equation, when the absolute value of the battery current I is greater than or equal to a predetermined value, the specific gravity of SOCi increases. In this way, by setting the value of the correction coefficient G2 table 140 having a large battery current I to 1, the operation of the conventional method that is not affected by the correction coefficient G2 increases the specific gravity of the SOCi to achieve a highly accurate SOC. Obtainable.

As described above, even if the battery has a large internal resistance as a battery characteristic, the table 140 is set so that the specific gravity of the SOCv is increased when the absolute value of the battery current I is not more than a predetermined value in accordance with the battery characteristic. By setting, the SOC calibration frequency can be improved. *

-Fourth Embodiment-
In the fourth embodiment, the block configuration diagram of the battery system of FIG. 1 described in the first embodiment, the functional block diagram showing the details of the battery state estimation device of FIG. 2, and the equivalent circuit of the battery of FIG. 3 are shown. Since the figure, the figure which shows the relationship between OCV and SOC of FIG. 4, and the figure which shows the relationship between the internal resistance of the battery of FIG. 5 and battery temperature are the same, the description is abbreviate | omitted.

FIG. 8 is a view showing a table 150 of the correction coefficient G2 in the fourth embodiment. The correction coefficient G2 shown in the table 150 is an example and is stored in the storage unit 120. In this table 150, the correction coefficient G2 in the range 151 in which the battery temperature T is 0 ° C. or less and the absolute value of the battery current I is 10 A or more is set to a value of 50 to 100, and the correction coefficient G2 is set to a value of 1 in other ranges. Is set. The weighting factor calculation unit 114 reads the correction factor G2 by referring to the table 150 in the storage unit 120 based on the detected battery current I and the battery temperature T, and calculates the weighting factor W based on the equation (5). To do.

Depending on the battery, when the battery temperature is low and the battery current is small, an event may occur in which the battery voltage greatly deviates from the relationship of equation (3). For such a battery, according to the conventional expression corresponding to Expression (5) (expression not including the correction coefficient G2), the specific gravity of the SOCv is increased by the weighting coefficient W because the battery current is small. As described above, since the relationship of Formula (3) is not satisfied, the SOCv error becomes large, and this becomes the final SOC, so that the SOC error becomes large. Therefore, in the present embodiment, when the battery temperature T is equal to or lower than a predetermined value and the absolute value of the battery current I is equal to or lower than the predetermined value, the correction coefficient G2 is set so that the specific gravity of SOCi increases.

This will be described with reference to the correction coefficient G2 table 150 shown in FIG. When the battery current I is small, for example, when the battery current I is 10 A and the battery temperature T is −10 ° C., the value 50 of the correction coefficient G 2 is read from the table 150. Here, when the internal resistance = 3 mΩ and G1 = 1, the weighting factor W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 10 × 3 × 50) × 1} = 1/1501
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/1501) × SOCv + (1500/1501) × SOCi
As can be seen from the SOCw equation, the SOCv is reflected only by 1/1501, the calibration frequency is low, and the specific gravity of SOCi is large.

Here, a case where G2 = 1 is described for comparison with the present embodiment. Assume that the battery current I is 10 A, the battery temperature T is −10 ° C., and G2 = 1. Here, when the internal resistance = 3 mΩ and G1 = 1, the weighting factor W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 10 × 3 × 1) × 1} = 1/31
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/31) × SOCv + (30/31) × SOCi
As can be seen from this SOCw equation, SOCv is reflected by 1/31 and calibration by SOCv occurs little by little, so it cannot be said that the specific gravity of SOCi is large.

On the other hand, in this embodiment, when the battery current I is large, for example, when the battery current I is 20 A and the battery temperature is −10 ° C., the value 1 of the correction coefficient G2 is read from the table 150. Here, when the internal resistance = 3 mΩ and G1 = 1, the weighting factor W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 20 × 3 × 1) × 1} = 1/61
Therefore, SOCw is as follows from the equation (1).
SOCw = (1/61) × SOCv + (60/61) × SOCi
As can be seen from this SOCw equation, compared to the case where the battery current I is small, the SOCv is reflected by 1/61, the calibration frequency increases, and the specific gravity of SOCi is small.

In this embodiment, for example, when the battery current I is 0 A and the battery temperature is −10 ° C., the value 100 of the correction coefficient G 2 is read from the table 150. Here, when the internal resistance = 3 mΩ and G1 = 1, the weighting factor W is calculated based on the equation (5) as follows.
W = 1 / {(1 + 0 × 3 × 100) × 1} = 1
Therefore, SOCw is as follows from the equation (1).
SOCw = 1 × SOCv + 0 × SOCi
As can be seen from the SOCw equation, SOCv is reflected. When the battery current I is 0 A, from Equation (3), OCV = CCV−Vp, and it is possible to calculate the SOC from the voltage with almost no influence of the current, and the error of the SOCv is small. Therefore, there is little concern that the accuracy will deteriorate even if the SOCv is reflected in the SOC, so that the SOC accuracy by calibration is improved.

According to the present embodiment, even when the battery temperature is low and the battery current is small, the battery temperature T is predetermined even if the battery voltage has a characteristic that causes an event that the battery voltage greatly deviates from the relationship of the expression (3). If the absolute value of the battery current I is less than or equal to a predetermined current, the table 150 is set so that the specific gravity of SOCi increases. Thereby, the precision of SOC can be improved. Furthermore, since the specific gravity of SOCv increases when the battery current is 0 A, the calibration frequency can be secured.

-Summary of each embodiment-
FIG. 9 is a diagram showing a summary of the first to fourth embodiments. For each embodiment, the value of the correction coefficient G2 to be set is shown according to the magnitude of the absolute value of the battery current I, the magnitude of the internal resistance R, and the range of the battery temperature T. As a result, the specific gravity of SOCv can be increased, or the specific gravity of SOCi can be increased. Thus, by setting the value of the correction coefficient G2 according to the characteristics of the battery 400 such as the magnitude of the absolute value of the battery current I, the magnitude of the internal resistance R, the range of the battery temperature T, etc., the SOCv is appropriately set. Alternatively, the specific gravity of SOCi can be increased.

According to the first to fourth embodiments described above, the following operational effects can be obtained.
(1) The battery control device 100 calculates the state of charge of the battery 400 by integrating the SOCv calculation unit 111 that calculates the state of charge of the battery 400 using the voltage across the battery 400 and the current I flowing through the battery 400. A weight for calculating the weighting coefficient W based on a calculation formula including the arithmetic unit 112, the absolute value of the magnitude of the current I, the internal resistance R of the battery, the first coefficient G1, and the second coefficient G2. A coefficient calculation unit 114, and SOCw calculation units MP1, MP2, DF, and a weighting addition of the charge state of the battery 400 calculated by the SOCv calculation unit 111 and the charge state of the battery 400 calculated by the SOCi calculation unit 112 using the weight coefficient W The first coefficient G1 of the calculation formula is related to the whole calculation formula, and the second coefficient G2 is related to the absolute value of the magnitude of the current I in the calculation formula. This facilitates setting of weights for calculating the SOC with high accuracy.

(2) In the battery control apparatus 100, the calculation formula is the following formula, and the weighting factor calculation unit 114 calculates the weighting factor W based on the calculation formula. This facilitates setting of weights for calculating the SOC with high accuracy.
W = 1 / {(1+ | I | × R × G2) × G1}

(3) In the battery control device 100, the SOCw calculation units MP1, MP2, DF, and AD are the state of charge SOCv of the battery 400 calculated by the SOCv calculation unit 111 and the state of charge SOCi of the battery 400 calculated by the SOCi calculation unit 112. Using the weighting factor W calculated by the weighting factor calculation unit 114, weighting addition is performed based on the following equation. This facilitates setting of weights for calculating the SOC with high accuracy.
SOCw = W × SOCv + (1-W) × SOCi

(4) In the battery control apparatus 100, the weighting factor calculation unit 114 is a current that flows in the battery 400 when the temperature T of the battery 400 is in the range of the first predetermined value or higher on the low temperature side and the second predetermined value or lower on the high temperature side. When the absolute value of I is greater than or equal to a predetermined current, the second coefficient G2 is set to a value greater than 1, and the SOCw calculation units MP1, MP2, DF, and AD have the first predetermined value when the temperature T is low. If the absolute value of the current I flowing through the battery 400 is greater than or equal to the predetermined current when the temperature is higher than the second predetermined value on the high temperature side, the specific gravity of the state of charge of the battery calculated by the SOCi calculation unit 112 is increased. To do. Thereby, even if the battery has a low low temperature region and a small internal resistance, the weighting factor W is sufficiently small when the battery current is large, the specific gravity of SOCi is increased, and the accuracy of the SOC is improved.

(5) In the battery control device 100, the weighting coefficient calculation unit 114 sets the second coefficient G2 to 0 when the absolute value of the current I flowing through the battery 400 is equal to or less than a predetermined current, and calculates SOCw. The units MP1, MP2, DF, and AD increase the specific gravity of the state of charge of the battery 400 calculated by the SOCv calculation unit 111 when the absolute value of the current I flowing through the battery 400 is equal to or less than a predetermined current. As a result, even if the battery has a large internal resistance as a battery characteristic, if the absolute value of the battery current I is less than or equal to a predetermined value in accordance with the battery characteristic, the table 140 is set so that the specific gravity of the SOCv increases. By setting, the SOC calibration frequency can be improved.

(6) In the battery control device 100, the weighting factor calculation unit 114 determines that the first value when the temperature T of the battery 400 is equal to or lower than the predetermined temperature and the absolute value of the current I flowing through the battery 400 is equal to or lower than the predetermined current. The coefficient G2 of 2 is set to a value greater than 1, and the SOCw calculation units MP1, MP2, DF, and AD have the temperature T of the battery 400 equal to or lower than a predetermined temperature and the absolute value of the current I flowing through the battery 400 is predetermined. When the current is less than the current, the specific gravity of the state of charge of the battery 400 calculated by the SOCi calculation unit 112 is increased. Thereby, the precision of SOC can be improved by this.

(7) In the battery control device 100, the weighting coefficient calculation unit 114 sets the first coefficient G1 to a value equal to or less than a predetermined value. Thereby, the setting by the second coefficient G2 can be made more effective.

(Modification)
The present invention can be implemented by modifying the first to fourth embodiments described above as follows.
(1) The weighting factor calculation unit 114 has been described as an example in which the weighting factor W is calculated based on Expression (5). However, the weighting factor W may be calculated based on the following equation (5 ′). Here, K1 = 1 / G1. That is, the coefficients K1 and G1 are both coefficients related to the entire calculation formula.
W = K1 × 1 / (1+ | I | × R × G2) (5 ′)

The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. . Moreover, it is good also as a structure which combined the above-mentioned embodiment and a modification.

100: Battery control device,
110 ... Battery state estimation device,
111 ... SOCv calculation unit,
112 ... SOCi calculation part,
114... Weight coefficient calculation unit,
130 ... Correction coefficient G2 table 140 in the second embodiment ... Correction coefficient G2 table 150 in the third embodiment ... Correction coefficient G2 table 200 in the fourth embodiment ... Measurement unit,
300 ... output section,
400 ... Battery,
1000 ... Battery system

Claims

An SOCv calculator that calculates the state of charge of the battery using the voltage across the battery;
An SOCi computing unit that calculates the state of charge of the battery by integrating the current I flowing through the battery;
A weighting factor calculation unit that calculates a weighting factor W based on a calculation formula including an absolute value of the magnitude of the current I, an internal resistance R of the battery, a first coefficient G1, and a second coefficient G2. When,
An SOCw computing unit that weights and adds the state of charge of the battery calculated by the SOCv computing unit and the state of charge of the battery calculated by the SOCi computing unit using the weighting factor W;
The first coefficient G1 of the calculation formula relates to the whole calculation formula, and the second coefficient G2 is a battery control device according to an absolute value of the magnitude of the current I in the calculation formula.
The battery control device according to claim 1,
The calculation formula is the following formula, and the weight coefficient calculation unit calculates the weight coefficient W based on the calculation formula.
W = 1 / {(1+ | I | × R × G2) × G1}
The battery control device according to claim 1 or 2,
The SOCw calculation unit includes the battery state of charge SOCv calculated by the SOCv calculation unit, the battery state of charge SOCi calculated by the SOCi calculation unit, and the weighting factor W calculated by the weighting factor calculation unit. A battery control apparatus that uses and weights and adds based on the following equation.
SOCw = W × SOCv + (1-W) × SOCi
In the battery control device according to any one of claims 1 to 3,
The weighting factor calculation unit has a temperature T of the battery in a range not lower than a first predetermined value on the low temperature side and not higher than a second predetermined value on the high temperature side, and an absolute value of the current I flowing through the battery is not lower than a predetermined current. The second coefficient G2 is set to a value larger than 1,
When the temperature T is in the range of the first predetermined value or higher on the low temperature side and the second predetermined value or lower on the high temperature side, and the absolute value of the current I flowing through the battery is equal to or higher than the predetermined current Is a battery control device that increases the specific gravity of the state of charge of the battery calculated by the SOCi calculation unit.
In the battery control device according to any one of claims 1 to 3,
The weighting factor calculation unit sets the second coefficient G2 to a value of 0 when the absolute value of the current I flowing through the battery is equal to or less than a predetermined current;
The SOCw calculation unit increases the specific gravity of the state of charge of the battery calculated by the SOCv calculation unit when the absolute value of the current I flowing through the battery is equal to or less than a predetermined current.
In the battery control device according to any one of claims 1 to 3,
The weight coefficient calculation unit sets the second coefficient G2 to be greater than 1 when the battery temperature T is equal to or lower than a predetermined temperature and the absolute value of the current I flowing through the battery is equal to or lower than a predetermined current. Set the value to
When the battery temperature T is equal to or lower than a predetermined temperature and the absolute value of the current I flowing through the battery is equal to or lower than the predetermined current, the SOCw calculation unit calculates the battery charge calculated by the SOCi calculation unit. A battery control device that increases the specific gravity of the state.
In the battery control device according to any one of claims 4 to 6,
The weight control unit is a battery control device that sets the first coefficient G1 to a value equal to or less than a predetermined value.