JP2023073549A - Battery management device, battery management method, and battery management program - Google Patents

Abstract

To provide a battery management device capable of acquiring an accurate SOC of a battery without relying only on the SOC acquired by a BMU.SOLUTION: A battery management device according to the present invention estimates a state of charge (SOC) by employing an amount of fluctuation of a battery voltage in a first charging operation or a first discharging operation, and an amount of fluctuation of the battery voltage in a second charging operation or a second discharging operation, and referring to data describing a relationship between the amounts of fluctuation and the SOC.SELECTED DRAWING: Figure 6

Description

The present invention relates to technology for managing the state of a battery.

A voltage (cell voltage) output by a lithium-ion battery cell is generally measured or obtained by a battery management unit (BMU) that controls a battery cell (or an assembled battery cell in which a plurality of battery cells are connected). The BMU uses the measured value to calculate the state of charge (SOC) of the battery cell. The BMU transmits the calculation result to a higher-level device by CAN (Control Area Network) communication, for example.

As the situations in which storage batteries are used become more diverse, the need for accurately estimating the SOC is increasing. For example, when transporting a lithium metal battery or a lithium ion battery, it may be required that the SOC be a predetermined percentage or less of the rated capacity (eg, 30% or less of the rated capacity). Alternatively, when connecting a storage battery from the demand side to the power system, it is necessary to accurately grasp the SOC in order to drive the storage battery according to the operation schedule.

Patent Literature 1 below discloses that "SOC and SOH are estimated with good accuracy considering not only the process value of the battery but also the cross-correlation between SOC and SOH. 'In the battery controller 6BC, the BCIA 9 includes an internal resistance measurement unit 96 that measures the 25°C conversion value R25 of the internal resistance of the battery 5 and an open circuit voltage measurement unit that measures the 25°C conversion value OCV25 of the open voltage. 97. The CPU 8 stores an equation storage unit 86 that stores a first equation representing the relationship between OCV25 and SOH and SOC, and a second equation representing the relationship between R25 and SOH and SOC, and the measurement results of R25 and OCV25. It is provided with a solving unit 87 that applies to the equations and obtains SOH and SOC as solutions of the simultaneous equations. (see abstract).

JP 2017-129401 A

The host device performs various operations based on the SOC obtained from the BMU. In principle, this is the same when transporting the above-mentioned lithium-ion batteries, etc., and in the case of storage batteries on the consumer side, and it is considered normal to realize each application based on the SOC obtained from the BMU. . However, the SOC obtained from the BMU may be notified with some margin. For example, when the actual SOC is 80%, the BMU may report to the host device that the SOC is 70%. An application executed by a host device (eg, display of remaining capacity in an electric vehicle) may present the SOC with more leeway. In this way, the SOC at the time the user recognizes it does not necessarily match the SOC notified by the BMU, and the SOC notified by the BMU does not always match the actual SOC. , I know from experience.

When the output voltage from the battery is measured while the storage battery is discharging (the same applies during charging, and the same applies hereinafter), large noise may be superimposed on the measurement result. The BMU performs noise removal processing on the measurement result and notifies the result to the host device. Along with this noise removal, there is a possibility that the measurement result reported by the BMU to the higher-level device will deviate from the actual SOC.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery management apparatus capable of obtaining an accurate SOC of a battery without relying solely on the SOC obtained by the BMU. and

A battery management apparatus according to the present invention uses a variation in battery voltage in a first charging operation or a first discharging operation and a variation in battery voltage in a second charging operation or a second discharging operation to SOC is estimated by referring to data that describes the relationship between and SOC.

According to the battery management device of the present invention, the accurate SOC of the battery can be acquired without relying only on the SOC acquired by the BMU.

FIG. 4 is a schematic diagram showing how a BMU acquires the SOC of a battery cell; 4 is an example of a battery voltage waveform measured or acquired by a BMU during a battery discharging operation; 1 is a configuration diagram of a battery management device 100 according to Embodiment 1. FIG. An example of a discharging operation when the battery management device 100 estimates the SOC of the battery 200 is shown. FIG. 4 is a diagram showing the relationship between the battery voltage and the SOC at the time when the battery voltage has stabilized over time after the start of the rest period; 4 is a diagram showing an example of data used by a computing unit 120 to estimate the SOC of a battery 200 and a procedure for estimating the SOC using this data; FIG. FIG. 3 is a schematic diagram illustrating a procedure for estimating an SOC using a battery voltage acquired from a BMU by a calculation unit 120; FIG. 11 is a schematic diagram illustrating a procedure for estimating an SOC by the battery management device 100 according to the third embodiment; 4 is a diagram showing another configuration example of the battery management device 100. FIG. A configuration example in which the detection unit 130 is connected to the battery 200 is shown. 4 is a flow chart for explaining a procedure for calculating Ri and SOH by a computing unit 120; 4 is a graph showing changes over time in the current and voltage output by the battery 200 during a rest period after discharging. 4 is a graph showing temporal changes in current and voltage output by the battery 200 during a rest period after charging. 4 is a diagram showing the structure of a relationship table 141 and an example of data; FIG. This is an example of a scene in which the battery management device 100 estimates the SOC of the battery 200. FIG. This is an example of a scene in which the battery management device 100 estimates the SOC of the battery 200. FIG. An example of discharge operation is shown. 17 is a configuration diagram of a power system 1700 according to Embodiment 6. FIG. It is an example of an operation schedule of the power system 1700. FIG. It is an example of a user interface provided by the battery management device 100 .

<Embodiment 1>
FIG. 1 is a schematic diagram showing how a BMU acquires the SOC of a battery cell. The BMU is connected to one or more battery cells, calculates the SOC using the output voltage and output current of the battery cells, and reports the result to the host device. The host device can visually display the SOC, for example, on a screen interface as shown in the lower part of FIG. If the SOC is close to full charge, the battery icon will be displayed as full. Alternatively, the SOC numerical value itself can also be presented.

FIG. 2 is an example of a battery voltage waveform measured or acquired by the BMU during the battery discharging operation. A certain amount of noise is superimposed on the measured value of the battery voltage (output voltage from the battery). It is empirically known that large noise is superimposed especially during discharge operation. Although the noise in the rest period (period in which neither discharging nor charging is performed) following the discharging operation is relatively small, a certain amount of noise is superimposed on the measurement results. The left diagram of FIG. 2 shows a voltage waveform on which noise is superimposed. Therefore, the BMU acquires a voltage waveform as shown in the right diagram of FIG. 2 by performing noise removal processing, reports this to the host device, or estimates the SOC based on this. The same is true during the charging operation.

As shown in Fig. 2, when the BMU performs noise removal on the battery voltage and then reports the measurement results to the host device, the measurement results are offset by the noise removal processing, and the host device is not accurate. It may not be possible to obtain accurate measurement results. For example, according to the result of measuring the cell voltage during the discharge operation, the battery voltage monotonously decreases as the discharge progresses, but the battery voltage waveform output by the BMU quickly stabilizes. Therefore, it is presumed that there is an offset between the actual battery voltage and the value measured by the BMU. In the idle period, it is estimated that an offset is similarly superimposed on the measurement result by the BMU, although it is not as large as in the discharging operation.

FIG. 3 is a configuration diagram of the battery management device 100 according to Embodiment 1 of the present invention. The battery management device 100 is a device that manages the state of the battery 200 . The battery management device 100 includes a communication section 110 , a calculation section 120 , a detection section 130 and a storage section 140 . The detection unit 130 acquires the output voltage, output current, temperature, and the like of the battery 200 . The detection unit 130 itself does not necessarily need to measure these, and the measurement results may be obtained from the BMU, for example. Operation unit 120 estimates the SOC of battery 200 using these measurement results. Communication unit 110 transmits the estimation result to the external device. The storage unit 140 is a device that stores data used by the calculation unit 120 .

FIG. 4 shows an example of a discharging operation when battery management device 100 estimates the SOC of battery 200 . When the battery management device 100 estimates the SOC of the battery 200, the battery 200 performs the discharge operation and the subsequent rest period twice, respectively, as illustrated in FIG. These operations may be controlled by the battery management device 100 or by another control device. That is, it suffices if the change over time of the battery voltage that accompanies these operations can be obtained.

It is assumed that calculation unit 120 has previously grasped the SOH (State Of Health: deterioration state) of battery 200 at the time of starting estimation of the SOC of battery 200 . Any known technique can be used as a technique for obtaining SOH, and one example thereof will be described later. By multiplying the rated capacity [Ah] of battery 200 by the SOH, calculation unit 120 can calculate the full charge capacity [Ah] of battery 200 at that time. This full charge capacity can be regarded as SOC=100% at that time.

Arithmetic unit 120 acquires battery voltage V1 at the time when battery 200 starts the first discharging operation (first discharging operation). The calculation unit 120 acquires the time length t1 during which the battery 200 performed the first discharge operation, and multiplies the discharge current by t1 to calculate the amount of discharge. The calculation unit 120 can obtain the SOC changed by the first discharge operation from the ratio of the discharge amount and the full charge capacity.

Arithmetic unit 120 acquires battery voltage V2 during the rest period (first rest period) after the first discharge operation. Calculation unit 120 obtains as V2 the battery voltage at the time when the battery voltage variation over time stabilizes in the first idle period. The length of time from the start of the idle period until the battery voltage stabilizes is assumed to be about several seconds, and it is not necessary to adopt a voltage that takes several tens of minutes to stabilize like the open circuit voltage as V2.

The calculator 120 calculates a voltage change (ΔV12=V1−V2) from V1 to V2. Thereby, the calculation unit 120 can obtain the relationship between the amount of change in SOC due to the first discharge operation and the amount of change in battery voltage due to the first discharge operation.

Arithmetic unit 120 acquires time length t2 during which battery 200 performs the second discharge operation (second discharge operation), and multiplies the discharge current by t2 to calculate the amount of discharge. The calculation unit 120 can obtain the SOC changed by the second discharge operation from the ratio of the discharged amount and the full charge capacity.

Arithmetic unit 120 acquires battery voltage V3 during the rest period (second rest period) after the second discharge operation. Similar to V2, calculation unit 120 acquires as V3 the battery voltage at the time when the battery voltage variation over time stabilizes during the second rest period. The length of time from the start of the first rest period to V2 and the length of time from the start of the second rest period to V3 may be the same or different.

The calculation unit 120 calculates a voltage change (ΔV23=V2−V3) from V2 to V3. Thereby, the calculation unit 120 can obtain the relationship between the amount of change in the SOC due to the second discharge operation and the amount of change in the battery voltage due to the second discharge operation.

FIG. 5 is a diagram showing the relationship between the battery voltage and the SOC at the point in time when the variation in battery voltage with time stabilizes after the start of the rest period. The data shown in FIG. 5 can be acquired in advance by experiment, for example. By differentiating the relationship indicated by this data (obtaining the change in battery voltage with respect to the change in SOC), the data curve shown in FIG. 6 can be obtained.

FIG. 6 is a diagram showing an example of data used by calculation unit 120 to estimate the SOC of battery 200 and a procedure for estimating the SOC using this data. This data describes the relationship between the battery voltage variations (eg, ΔV12, ΔV23) accompanying the discharge operation illustrated in FIG. 4 and the SOC. This data is created in advance and stored in the storage unit 140 before estimating the SOC.

Calculation unit 120 identifies data points corresponding to voltage fluctuations (ΔV12 and ΔV23) in each of the two discharge operations described in FIG. 4 from the data in FIG. The resulting two data points correspond to the SOC at the completion of each discharge operation. However, there may be a plurality of SOC candidates corresponding to each voltage fluctuation. In the data example of FIG. 6, there are two SOC candidates corresponding to ΔV12 and four SOC candidates corresponding to ΔV23.

Therefore, calculation unit 120 further identifies SOC candidates corresponding to the amount of discharge in the second discharge operation. For example, when the discharge amount in the second discharge operation corresponds to SOC 1%, an SOC candidate having a difference of 1% between the SOC corresponding to ΔV12 and the SOC corresponding to ΔV23 is specified. It can be estimated that the SOC candidate identified by this represents the true SOC of battery 200 . In the data example of FIG. 6, this corresponds to data points near SOC=24%. Therefore, calculation unit 120 can estimate that the SOC of battery 200 is approximately 24%.

More simply, calculation section 120 may identify SOC candidates that correspond to difference VR between ΔV12 and ΔV23. This is because VR corresponds to the amount of discharge in the second discharge operation. In the data example of FIG. 6, data points near SOC=24% correspond to this. In this case, the calculation unit 120 does not need to calculate the discharge amount (I×t1, I×t2, etc.) associated with the discharge operation, and the data points corresponding to ΔV12, ΔV23, and VR are specified on the data shown in FIG. Enough.

<Embodiment 1: Summary>
The battery management apparatus 100 according to the first embodiment obtains V2 and calculates ΔV12 during the first rest period after the first discharge period, and obtains V3 and calculates ΔV23 during the second rest period after the second discharge period. are calculated, and the SOC of the battery 200 is estimated by referring to the data in FIG. 6 using these. By using ΔV12 or ΔV23, which is the difference between V1 to V3 instead of V1 to V3 itself, even if an offset in the BMU measurement process is superimposed on each of V1 to V3, the effect can be canceled to some extent. can be done. Furthermore, the SOC can be accurately obtained from the measurement results that are less dependent on the SOC measured by the BMU and are less affected by the offset.

The relational data (the data illustrated in FIG. 6) used by the battery management device 100 according to the first embodiment to estimate the SOC is the difference between the change in the SOC accompanying the charge/discharge operation and the change in the battery voltage at that time. The calculation unit 120 identifies data points corresponding to ΔV12 and ΔV23 as SOC candidates, and identifies SOC candidates corresponding to the charge/discharge amount from among the SOC candidates, thereby estimating the SOC. . As a result, even when there are multiple SOC candidates, the SOC corresponding to the charge/discharge amount can be specified accurately.

The relational data (the data illustrated in FIG. 6) used by the battery management device 100 according to the first embodiment to estimate the SOC is the difference between the change in the SOC accompanying the charge/discharge operation and the change in the battery voltage at that time. Calculation unit 120 identifies data points corresponding to ΔV12 and ΔV23 as SOC candidates, and calculates battery voltage variation (VR ) to estimate the SOC. Thus, without calculating the charge/discharge amount itself, the SOC corresponding to the charge/discharge amount can be accurately specified based on the variation in the battery voltage that accompanies the charge/discharge operation.

In the first embodiment, an example in which the battery voltage is obtained during the rest period after the discharging operation has been described, but the battery voltage can be obtained during the rest period after the charging operation and the SOC can be estimated by a similar method. The same applies to the following embodiments. For example, when charging is started, the remaining capacity of the battery 200 is set to 0, and the change in battery voltage caused by each of the two charging operations may be acquired. Also in the pause period after the charging operation, the battery voltage may be measured after a period of several seconds in which the battery voltage is stabilized.

<Embodiment 2>
In Embodiment 1, the procedure for more accurately estimating the SOC has been described in consideration of the fact that the battery voltage obtained from the BMU is not necessarily accurate. However, once the battery voltage history acquired from the BMU is accumulated to some extent, it is possible to estimate the correspondence relationship between the battery voltage acquired from the BMU and the accurate SOC. Therefore, in a second embodiment of the present invention, an operation example of learning the correspondence between the battery voltage obtained from the BMU and the accurate SOC and estimating the SOC using this will be described. Since the configuration of the battery management device 100 is the same as that of the first embodiment, the following mainly describes matters related to learning.

FIG. 7 is a schematic diagram illustrating a procedure for estimating the SOC using the battery voltage acquired from the BMU by the calculation unit 120. As shown in FIG. Calculation unit 120 estimates the SOC of battery 200 using battery voltages V1 to V3 according to the procedure described in the first embodiment. V1 to V3 used at this time are acquired from, for example, the BMU. As described above, these V1 to V3 may be offset from the true values, but the calculation unit 120 uses V1 to V3 obtained from the BMU as they are to estimate the SOC.

Calculation unit 120 stores in storage unit 140 the correspondence between the SOC estimation result and the set of V1 to V3 used for estimating this. The calculation unit 120 stores the same correspondence relationship in the storage unit 140 each time the SOC is estimated. By accumulating the correspondence in this manner, the calculation unit 120 can estimate the SOC using the correspondence when acquiring new V1 to V3.

As a method of estimating the SOC by the calculation unit 120 using V1 to V3, for example, the following can be considered: (b) SOC estimation results are obtained as the output of the learner by learning by an appropriate machine learning method and inputting new V1 to V3 into the learning model obtained as a result; (b) V1 to V3 and plot the SOC estimation results using this, and calculate the equation that best approximates these correspondence relationships. By substituting new V1 to V3 into this equation, the SOC estimation result is obtained.

In the method of the second embodiment, it is first necessary to accumulate estimation results to some extent according to the method of the first embodiment. It is useful to be able to get the SOC directly from the value.

<Embodiment 3>
FIG. 8 is a schematic diagram illustrating a procedure for estimating the SOC by the battery management device 100 according to Embodiment 3 of the present invention. In the second embodiment, learning the relationship between V1 to V3 obtained from the BMU and the SOC has been described. In the third embodiment, instead of this, an example of learning the correspondence relationship between the SOC obtained from the BMU and the SOC estimated by the battery management device 100 will be described. Since the configuration of the battery management device 100 is the same as that of the first embodiment, the following mainly describes matters related to learning.

The BMU uses the battery voltage and battery current to calculate the SOC. The calculation unit 120 acquires this SOC. Aside from this, the calculation unit 120 estimates the SOC of the battery 200 by the method described in the first embodiment. The calculation unit 120 learns the correspondence relationship between the SOC obtained from the BMU and the SOC estimated by the calculation unit 120 in the same manner as in the second embodiment. After the learning result is accumulated to some extent, the calculation unit 120 can obtain the SOC estimation result by inputting the new SOC acquired from the BMU to the learning model.

<Embodiment 4>
Embodiment 4 of the present invention describes a method of estimating the SOH (or internal resistance Ri, hereinafter the same) of the battery 200 described in Embodiments 1-3. Although the configuration of the battery management device 100 is similar to that of the above embodiment, the following modifications are also possible. Similar modifications can be adopted in other embodiments.

FIG. 9 is a diagram showing another configuration example of the battery management device 100. As shown in FIG. The battery management device 100 does not necessarily have to be a device that is directly connected to the battery 200 to receive power supply, and shows a configuration that does not include the communication unit 110 and the detection unit 130 shown in FIG. . In FIG. 9 , battery management device 100 acquires voltage V, current I, and temperature T of battery 200 from communication unit 110 . Specifically, the detection unit 150 included in the battery management device 100 receives these detection values via, for example, a network, and the calculation unit 120 uses these detection values to calculate SOH.

FIG. 10 shows a configuration example in which the detection unit 130 is connected to the battery 200. As shown in FIG. The detection unit 130 may be configured as a part of the battery management device 100 or may be configured as a module separate from the battery management device 100 . The detection unit 130 includes a voltage sensor 131, a temperature sensor 132, and a current sensor 133 in order to obtain the voltage V, temperature T, and current I when the battery 200 is charged and discharged.

The voltage sensor 131 measures the voltage across the battery 200 (the voltage output by the battery 200). The temperature sensor 132 is connected to, for example, a thermocouple included in the battery 200 and measures the temperature of the battery 200 through this. Current sensor 133 is connected to one end of battery 200 and measures the current output by battery 200 . Temperature sensor 132 is optional and need not be provided.

FIG. 11 is a flow chart for explaining the procedure by which the calculator 120 calculates Ri and SOH. The calculation unit 120 starts this flowchart at an appropriate timing such as, for example, when the battery management device 100 is activated, when instructed to start this flowchart, or at predetermined intervals. Each step in FIG. 11 will be described below.

(Fig. 11: Step S1101)
Arithmetic unit 120 determines whether it is a rest period after charging or a rest period after discharging. If the current period is not the rest period, the flowchart ends. If it is the pause period, the process proceeds to S1102. For example, a rest period after discharging means that the current output by the battery 200 changes from a negative value (I<0) toward zero, and (b) changes from a negative value to a value near zero and stabilizes. (|I|<threshold), or the like.

(Fig. 11: Step S1102)
The calculator 120 calculates ΔVa and ΔVb. ΔVa is the amount of change in the output voltage of the battery 200 from the first calculation time after the end of the rest period to the first time when the first period ta has passed. ΔVb is the amount of change in the output voltage of battery 200 from the second time point after the first time point to the second time point after the second period tb has passed. These calculation procedures will be described later.

(Fig. 11: Step S1103)
The calculator 120 calculates Ri and SOH according to Equations 1 and 2 below. f _Ri defines Ri as a function of ΔVa. f _Ri has a parameter (c_Ri_T) that varies with the temperature of the battery 200 and a parameter (c_Ri_I) that varies with the output current of the battery 200 . f _SOH defines SOH as a function of ΔVb. f _SOH has a parameter (c_SOH_T) that varies with the temperature of the battery 200 and a parameter (c_SOH_I) that varies with the output current of the battery 200 . These parameters are defined by relation table 141 . A specific example of each function and a specific example of the relationship table 141 will be described later. _fRi and _fSOH are formulas formed based on, for example, experimental data for each lot.

(Fig. 11: Step S1103: calculation formula)
Ri= _fRi (ΔVa, c_Ri_T_1, c_Ri_T_2, ..., c_Ri_I_1, c_Ri_I_2, ...) (1)
SOH = f _SOH (ΔVb, c_SOH_T_1, c_SOH_T_2, ..., c_SOH_I_1, c_SOH_I_2, ...) (2)

FIG. 12 is a graph showing temporal changes in the current and voltage output by the battery 200 during the rest period after discharging. ΔVa in S1102 is the amount of change in the output voltage of the battery 200 from the time when the discharge ends or after the first calculation time to the first time when the first period ta has passed. The inventors have found that the output voltage immediately after the end of discharging clearly shows the voltage fluctuation due to the internal resistance of the battery 200 . That is, it can be said that the fluctuation (ΔVa) of the output voltage during this period has a strong correlation with Ri. In the present embodiment, this fact is used to estimate Ri by ΔVa. The optimum values for the start time and the time length of ta can be obtained based on the section from the end of discharge to the maximum point of the slope change rate in the voltage change curve over time. Incidentally, when specifying the above-mentioned section, depending on the type of battery, the device, the accuracy, etc., it is possible to select a region in the vicinity of both ends of the above-mentioned section, or an area including both ends.

ΔVb in S1102 is the amount of change in the output voltage of the battery 200 from the time when the period ta has passed or from the second starting time after that to the second time when the second period tb has passed. It can be seen that ΔVa immediately after the end of discharge has a correlation with Ri, while the period after that in which the output voltage gradually fluctuates has a correlation with SOH. , the inventors have found. In the present embodiment, this fact is utilized to estimate SOH by ΔVb. The optimum values for the start time and time length of tb are based on the section from the maximum point of the rate of change in the slope of the voltage change curve over time after the end of the discharge until the slope change of the voltage change curve asymptotically becomes constant. can be obtained. Incidentally, when specifying the above-mentioned section, depending on the type of battery, the device, the accuracy, etc., it is possible to select a region in the vicinity of both ends of the above-mentioned section, or an area including both ends.

The start time of ta does not necessarily have to be the same as the discharge end time, but it is desirable that it be close to the discharge end time. The start time of tb does not necessarily have to be the same as the end time of ta. In either case, ta and tb have a relationship of ta<tb. Regarding the magnitude of ΔVa and the magnitude of ΔVb, ΔVa may be larger, and ΔVb may be larger. Although ta<tb is set here, there may be a case where ta>tb or ta=tb depending on the type of battery, the device, the accuracy, etc. Therefore, a preferable relationship may be set as appropriate.

Experimental results by the inventors have shown that Ri and SOH can be accurately estimated even if the sum of ta and tb is, for example, several seconds. Therefore, according to the present embodiment, both Ri and SOH can be quickly estimated during the idle period.

FIG. 13 is a graph showing temporal changes in the current and voltage output by the battery 200 during the rest period after charging. ΔVa in S1102 may be the change in the output voltage of the battery 200 from the time when the charging is completed or after the first calculation time to the first time when the first period ta has passed, instead of the discharge. In this case, ΔVb in S1102 is the change in the output voltage of the battery 200 from the time when the period ta has passed or the second starting time after that until the second time when the second period tb has passed. The present inventors have found that ΔVa has a correlation with Ri and ΔVb has a correlation with SOH even in the rest period after charging. Therefore, in this embodiment, ΔVa and ΔVb in S1102 may be obtained after either charging or discharging.

FIG. 14 is a diagram showing the structure of the relationship table 141 and an example of data. The relationship table 141 is a data table that defines each parameter in Equations 1 and 2 and is stored in the storage unit 140 . Since c_Ri_I and c_SOH_I vary depending on the output current of the battery 200, they are defined for each output current value. Since c_Ri_T and c_SOH_T vary depending on the temperature of the battery 200, they are defined for each temperature. Since these parameters may have different characteristics between the rest period after discharging and the rest period after charging, the relationship table 141 defines each parameter for each of these periods.

When _fRi is a linear function of ΔVa, Ri can be expressed, for example, by Equation 3 below. This is because the slope of Ri is affected by temperature and the intercept is affected by current. In this case, c_Ri_T and c_Ri_I are each one.

Ri=c_Ri_T_1×ΔVa+c_Ri_I_1 (3)

When f _SOH is a linear function of ΔVb, SOH can be expressed by Equation 4 below, for example. This is because the slope of SOH is affected by temperature and the intercept is affected by current. In this case, c_SOH_T and c_SOH_I are each one.

SOH=c_SOH_T_1×ΔVb+c_SOH_I_1 (4)

<Embodiment 5>
FIG. 15A is an example of a scene in which battery management device 100 estimates the SOC of battery 200 . The charging operation described in the first embodiment can be performed, for example, by a charger that charges an electric device on which the battery 200 is mounted. For example, it is assumed that the battery 200 is installed in an electric vehicle 1500 (electrical equipment). The operator connects charging port 1501 provided in electric vehicle 1500 with charger 1502 to charge battery 200 . At this time, the measuring device 1503 arranged between the charger 1502 and the charging port 1501 measures the battery voltage and transmits the result to the battery management device 100 . The battery management device 100 and the measuring instrument 1503 can be connected via a network, for example. The calculation unit 120 estimates the SOC by the method described in the first embodiment using the battery voltage acquired from the measuring device 1503 .

In order to use the estimation method described in the first embodiment, it is necessary to perform the charging operation by the charger twice. Therefore, the operator performs two charging operations as described in the first embodiment. The calculation unit 120 acquires the battery voltage from the measuring device 1503 during the pause period after each charging operation. A period after the operator stops the charging operation can be used as the rest period.

FIG. 15B is an example of a scene in which battery management device 100 estimates the SOC of battery 200 . Similar to FIG. 15A, the battery 200 is installed in, for example, an electric vehicle, and the operator performs a charging operation via a charging port. The operator also connects an OBD (On Board Diagnostics) terminal 1504 to the electric vehicle. The OBD terminal 1504 measures the battery voltage and transmits the result to the battery management device 100 . The battery management device 100 and OBD terminal 1504 can be connected via a network, for example. The calculation unit 120 uses the battery voltage obtained from the OBD terminal 1504 to estimate the SOC by the method described in the first embodiment.

FIG. 16 shows an example of discharge operation. A discharging operation can be performed by operating an electrical load connected to an electrical device in which battery 200 is mounted. When battery 200 is mounted in electric vehicle 1500, battery 200 can be discharged by operating an air conditioner provided in electric vehicle 1500, for example. When the air conditioner is turned off, the battery 200 enters a rest period. The battery voltage during the idle period can be measured by the OBD terminal 1504, for example. Subsequent operations are the same. An air conditioner is one example of an electrical load, and other electrical loads may be used to discharge battery 200 .

<Embodiment 6>
FIG. 17 is a configuration diagram of a power system 1700 according to Embodiment 6 of the present invention. The power system 1700 is a system that supplies power output from the solar cell 1701 and the battery 200 to the power system. Solar cell 1701 is driven by power controller 1702 and battery 200 is driven by power controller 1703 . The power control device 1703 measures the output voltage of the battery 200 and the like, and uploads the measurement results to the data server. Battery management device 100 estimates the SOC of battery 200 using the uploaded measurement results. Management server 1704 controls the entire power system 1700 . Commands to power control devices 1702 and 1703 are sent from, for example, battery management device 100 or management server 1704 via PLCs (programmable logic controllers). Power controllers 1702 and 1703 control solar cell 1701 and battery 200, respectively, according to the instructions.

FIG. 18 is an example of an operation schedule for power system 1700 . When connecting the power system 1700 to the power grid, it may be required to submit an operation schedule (for example, the amount of power generation for each hour) to the regulatory authority in advance. This operation schedule is created according to the power generation amount prediction result of the solar cell 1701 during the operation period. However, the predicted value of the power generation amount of the solar cell 1701 has a relatively high possibility of deviating from the actual value. Even in this case, the battery 200 can be used supplementarily so that the power supplied to the power grid by the power system 1700 conforms to the operation schedule. This is because the surplus power can be used to charge the battery 200 and the shortage of power can be compensated by discharging the battery 200 .

In order to use the battery 200 in this way, it is necessary to prepare the SOC of the battery 200 in a suitable state in advance. As a prerequisite for this, it is necessary to accurately measure the SOC of the battery 200 . The battery management device 100 estimates the SOC by the method described in the above embodiments. The operator of power system 1700 can prepare battery 200 in advance according to the estimation result.

If the operation schedule of the electric power system 1700 is, for example, 06:00 to 18:00, the SOC of the battery 200 must be prepared before 06:00. In the example of FIG. 18, this is prepared during period 1802 . Further, as a premise, the SOC is estimated in period 1801 prior to period 1802 . In order to secure a sufficient preparation period, it is desirable that the period 1801 be as short as possible.

<Embodiment 7>
FIG. 19 is an example of a user interface provided by the battery management device 100. As shown in FIG. The user interface can present the estimated SOC of the battery 200, the measurement results of ΔV12 and ΔV23 described in the first embodiment, the change in battery voltage over time acquired from the BMU, and the like. For example, the user interface may be generated by the computing unit 120 and displayed on an appropriate display device, or data describing the user interface (eg, data specifying a screen layout such as HTML data) may be generated by the computing unit 120. It may be generated and sent to another display terminal, which renders it. You may provide by other suitable methods.

<Regarding Modifications of the Present Invention>
The present invention is not limited to the embodiments described above, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

In the above embodiment, it was explained that the detection unit 130 acquires the measurement results of the battery voltages V1 to V3 from the BMU. 1504).

In the above embodiment, the arithmetic unit 120 can be configured by hardware such as a circuit device implementing the function, or software implementing the function is executed by an arithmetic unit such as a CPU (Central Processing Unit). It can also be configured by

100: Battery management device 110: Communication unit 120: Calculation unit 130: Detection unit 140: Storage unit

Claims (14)

A battery management device that manages the state of a battery,
a detection unit that acquires a detected value of the voltage output by the battery;
a computing unit that estimates the state of the battery;
with
The computing unit determines the output voltage of the battery when the battery starts the first charging operation or the first discharging operation and the first rest period after the first charging operation or the first discharging operation is finished. calculating a first difference between the output voltage of the battery at a first time after initiation;
The calculation unit calculates the output voltage of the battery at the time when the battery starts the second charging operation or the second discharging operation after the end of the first rest period, and the output voltage of the battery and the second charging operation or the second discharging operation. Calculating a second difference between the output voltage of the battery at the time when a second time has elapsed since the start of the second rest period after the end,
The battery management, wherein the calculating unit estimates the state of charge of the battery by referring to data describing the relationship between the first difference, the second difference, and the state of charge of the battery. Device. The data includes a value obtained by converting the amount of charge or discharge of the battery from the start of charging or discharging until the end of charging or discharging to the state of charge, and a value obtained by converting the amount of charging or discharging of the battery from the time the battery starts charging or discharging to the end of charging or discharging. describing the relationship between changes in the output voltage of said battery to
The calculation unit refers to the data using the first difference to obtain a first candidate for the state of charge corresponding to the amount of charge or discharge of the battery in the first charging operation or the first discharging operation. and get
The computing unit refers to the data using the second difference to obtain a second candidate for the state of charge corresponding to the amount of charge or discharge of the battery in the second charging operation or the second discharging operation. and get
The calculation unit estimates the state of charge by specifying one of the first candidate and the second candidate that corresponds to the amount of charge in the second charging operation or the amount of discharge in the second discharging operation. The battery management device according to claim 1, characterized in that: The data includes a value obtained by converting the amount of charge or discharge of the battery from the start of charging or discharging until the end of charging or discharging to the state of charge, and a value obtained by converting the amount of charging or discharging of the battery from the time the battery starts charging or discharging to the end of charging or discharging. describing the relationship between changes in the output voltage of said battery to
The computing unit identifies data points described by the data that correspond to the first difference, the second difference, and the difference between the first difference and the second difference. The battery management device according to claim 1, wherein the state of charge is estimated by: The calculation unit is
a first output voltage of the battery at the time the first charging operation or the first discharging operation begins;
a second output voltage of the battery at the time when the first time has elapsed since the start of the first rest period;
a third output voltage of the battery at the time when the second time has elapsed since the start of the second rest period;
Estimate the state of charge for each combination of
The computing unit acquires measurement results of the first output voltage, the second output voltage, and the third output voltage from a measurement device that measures the output voltage of the battery independently of the battery management device. ,
The computing unit learns a correspondence relationship between the state of charge estimated for each combination and the measurement result,
The battery management according to claim 1, wherein the calculation unit estimates the state of charge by inputting the new measurement result obtained from the measurement device into the learned correspondence relationship. Device. The computing unit estimates the state of deterioration of the battery,
The battery management device according to claim 1, wherein the calculating unit calculates the state of charge at the time when the first charging operation starts, using the state of deterioration. The detection unit acquires a detected value of the current output by the battery,
The computing unit calculates, as a difference representing the change over time of the voltage output by the battery, the voltage at a first starting point after the charging or discharging end point of the battery, and the first period from the first calculated point. obtaining a first difference between the voltage at a first point in time after the
The calculation unit calculates, as the difference, a second difference between the voltage at a second time point after the first time point and the voltage at a second time point after the second time period has elapsed from the second time point. Acquired,
The computing unit acquires relational data describing the relationship between the first difference and the internal resistance of the battery and describing the relationship between the second difference and the deterioration state,
The computing unit estimates the internal resistance of the battery by referring to the relationship data using the first difference,
The battery management device according to claim 5, wherein the calculation unit estimates the deterioration state by referring to the relationship data using the second difference. The first charging operation and the second charging operation are performed via a charging port of an electrical device equipped with the battery,
2. The method according to claim 1, wherein the calculation unit calculates the first difference and the second difference caused by the first charging operation and the second charging operation performed via the charging port, respectively. Battery management device. The computing unit receives from a measuring instrument arranged between the charging port and the charger, or from a terminal connected to the electrical device and performing maintenance processing on the electrical device,
a first output voltage of the battery at the time the first charging operation or the first discharging operation begins;
a second output voltage of the battery at the time when the first time has elapsed since the start of the first rest period;
a third output voltage of the battery at the time when the second time has elapsed since the start of the second rest period;
8. The battery management device according to claim 7, wherein the battery management device acquires the . The first discharging operation and the second discharging operation are performed by an electrical load of an electrical device equipped with the battery,
2. The battery according to claim 1, wherein the calculation unit acquires the first difference and the second difference caused by the first discharge operation and the second discharge operation performed by the electrical load, respectively. management device. The first charging operation and the second charging operation, or the first discharging operation and the second discharging operation are performed by a control device that drives the battery,
The computing unit performs the above-described charging operation caused by the first charging operation and the second charging operation performed by the control device, or caused by the first discharging operation and the second discharging operation performed by the control device. The battery management device according to claim 1, wherein the first difference and the second difference are obtained respectively. The control device charges or discharges the battery according to a predetermined operation schedule based on power demand,
The control device performs the first charging operation and the second charging operation or the first discharging operation and the second discharging operation before charging or discharging the battery according to the operation schedule. ,
11. The battery management device according to claim 10, wherein the calculation unit estimates the state of charge before the control device charges or discharges the battery according to the operation schedule. The battery management device according to claim 1, further comprising a user interface for presenting the estimated state of charge. A battery management program for causing a computer to execute processing for managing the state of a battery, the computer comprising:
obtaining a detected value of the voltage output by the battery;
estimating the state of the battery;
and
In the estimating step, the computer stores the output voltage of the battery when the battery starts the first charging operation or the first discharging operation, and the output voltage after the first charging operation or the first discharging operation is completed. calculating a first difference between the output voltage of the battery and the output voltage of the battery at the time when the first time has elapsed since the first rest period of
In the estimating step, the computer stores the output voltage of the battery at the time when the battery starts the second charging operation or the second discharging operation after the end of the first rest period, the second charging operation or calculating a second difference between the output voltage of the battery at the time when a second time has elapsed since the start of the second rest period after the end of the second discharge operation;
In the estimating step, estimating the state of charge of the battery by referring to data describing the relationship between the first difference, the second difference, and the state of charge of the battery in the computer. A battery management program characterized by executing A method for managing the state of the battery using a battery management device that manages the state of the battery,
The battery management device
a detection unit that acquires a detected value of the voltage output by the battery;
a computing unit that estimates the state of the battery;
with
The computing unit determines the output voltage of the battery when the battery starts the first charging operation or the first discharging operation and the first rest period after the first charging operation or the first discharging operation is finished. calculating a first difference between the output voltage of the battery at a first time after initiation;
The calculation unit calculates the output voltage of the battery at the time when the battery starts the second charging operation or the second discharging operation after the end of the first rest period, and the output voltage of the battery and the second charging operation or the second discharging operation. Calculating a second difference between the output voltage of the battery at the time when a second time has elapsed since the start of the second rest period after the end,
The computing unit estimates the state of charge of the battery by referring to data describing the relationship between the first difference, the second difference, and the state of charge of the battery,
The method includes:
performing the first charging operation and the second charging operation via a charging port of an electrical device equipped with the battery;
measuring the output voltage of the battery using a measuring instrument arranged between the charging port and the charger, or using a terminal connected to the electrical equipment to perform maintenance processing on the electrical equipment; ,
estimating the state of charge by the battery management device using the output voltage;
How to have

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