Data interpolation system, data interpolation method, and data interpolation program

Abstract

In a data interpolation system 10, a data acquisition unit 111 acquires battery data including at least time series data of current and state of charge (SOC). A missing determination unit 113 determines whether or not the battery data includes a missing interval. An interpolation unit 115 interpolates battery data for a missing interval on the basis of at least battery data outside the missing interval. If there is a charged state before and / or after the missing interval, the interpolation unit 115 interpolates current data for the missing interval so that the discharge amount and the charge amount correspond to each other in a charge / discharge period from the SOC of the charged state immediately after the missing interval to a corresponding SOC toward the past, or a charge / discharge period from the SOC of the charged state immediately before the missing interval to a corresponding SOC toward the future.

Description

Data interpolation system, data interpolation method, and data interpolation program

[0001] The present disclosure relates to a data interpolation system, a data interpolation method, and a data interpolation program for interpolating missing sections of battery data.

[0002] Services that store data related to batteries installed in devices such as EVs and PCs on cloud servers and analyze the data are becoming popular. Devices that collect data collect data based on a fixed sampling period. However, due to noise inside or outside the device, data may not be collected properly, resulting in data being collected at intervals longer than the specified sampling interval. In this specification, a data section that does not meet the specified sampling interval is called a missing section.

[0003] The charge amount (Ah) obtained by integrating the current value is used to analyze the remaining capacity and deterioration of the battery. However, if the current data is missing, the current value cannot be integrated, making it difficult to analyze the battery.

[0004] Patent Document 1 discloses three interpolation methods for missing data: "interpolation using previous and following data," "interpolation using data with high similarity in time-dependent changes," and "interpolation using correlated data."

[0005] Japanese Patent Application Laid-Open No. 2019-176544

[0006] The above interpolation method requires certain prerequisites, such as data that exhibits consistent changes over time, sufficient previously acquired data, high similarity with previously acquired data, and consistent correlation. Maintaining interpolation accuracy is particularly difficult when daily operations vary and the system's operating state changes during periods of missing data. Maintaining interpolation accuracy is also difficult when the correlation changes due to battery degradation. For example, if the shape of the SOC (State of Charge)-OCV (Open Circuit Voltage) curve changes due to degradation, maintaining interpolation accuracy becomes difficult. Missing sections make battery analysis difficult.

[0007] The present disclosure has been made in consideration of these circumstances, and its purpose is to provide a technology for interpolating missing sections of battery data with high accuracy.

[0008] In order to solve the above problem, a data interpolation system according to one aspect of the present disclosure includes: a data acquisition unit that acquires battery data including at least time-series data of current and SOC; a loss determination unit that determines whether the battery data includes a loss section; and an interpolation unit that interpolates battery data for the loss section based on at least battery data other than the loss section. When at least one of the sections before and after the loss section is in a charged state, the interpolation unit interpolates current data for the loss section so that the discharge amount corresponds to the charge amount during a charge / discharge period from an SOC in a charged state immediately after the loss section to a corresponding SOC in the past, or during a charge / discharge period from an SOC in a charged state immediately before the loss section to a corresponding SOC in the future.

[0009] Any combination of the above components, and conversion of the expression of the present disclosure into an apparatus, system, method, computer program, etc., are also valid aspects of the present disclosure.

[0010] According to the present disclosure, missing sections of battery data can be interpolated with high accuracy.

[0011] 12(a)-(b) are diagrams for explaining a data interpolation system for battery data. FIG. 12(a) is a diagram showing an example of a condition table for determining the operating state of an electric vehicle. FIG. 12(b) is a diagram showing a first specific example of a first interpolation method. FIG. 12(b) is a diagram showing a second specific example of the first interpolation method. FIG. 12(b) is a diagram showing a third specific example of the first interpolation method. FIG. 12(a) is a diagram showing an example of an interpolation process using the first interpolation method of the data interpolation system according to the embodiment. FIG. 12(b) is a diagram showing an example of an SOC estimation for a missing section.

[0012] FIG. 1 is a diagram illustrating a data interpolation system 10 for battery data. The data interpolation system 10 is a system that interpolates data for a missing section when collected battery data includes a missing section as preprocessing for analysis of a secondary battery 21 installed in an electric vehicle 20. The data interpolation system 10 may be implemented, for example, on an in-house server installed in the in-house facility or data center of a business that provides analysis services for the secondary battery 21 installed in the electric vehicle 20. The data interpolation system 10 may also be implemented on a cloud server used based on a cloud service. The data interpolation system 10 may also be implemented on multiple servers distributed across multiple locations (data centers, in-house facilities). The multiple servers may be a combination of multiple in-house servers, a combination of multiple cloud servers, or a combination of an in-house server and a cloud server.

[0013] The secondary battery 21 mounted on the electric vehicle 20 supplies power to a drive motor (not shown). The secondary battery 21 is configured by connecting multiple cells or multiple parallel cell blocks in series. Each parallel cell block is configured by connecting multiple cells in parallel.

[0014] The cells can be lithium-ion battery cells, nickel-metal hydride battery cells, lead battery cells, etc. In the following, this specification assumes an example in which lithium-ion battery cells (nominal voltage: 3.6-3.7V) are used. The number of cells or parallel cell blocks connected in series is determined according to the voltage of the drive motor.

[0015] The voltage sensor 22 detects the voltage across each of the series-connected cells or parallel cell blocks. A shunt resistor is connected in series with each of the series-connected cells or parallel cell blocks. The current sensor 23 detects the current flowing through the series-connected cells or parallel cell blocks based on the voltage across the shunt resistor. A Hall element may be used instead of the shunt resistor. The temperature sensor 24 detects the temperature of the multiple cells or parallel cell blocks based on the divided voltage between a thermistor and a resistor installed in at least one of the multiple cells or parallel cell blocks.

[0016] The control unit 25 is configured by a BMU (Battery Management Unit) and an ECU (Electronic Control Unit) working together. The BMU estimates the SOC by combining the OCV method and the current integration method. The OCV method is a method of estimating the SOC based on the measured OCV of the cell and the SOC-OCV curve of the cell. The current integration method is a method of estimating the SOC based on the OCV at the start of charging and discharging the cell and the integrated value of the measured current. In the current integration method, current measurement errors accumulate as the charging and discharging time becomes longer. Therefore, it is preferable to correct the SOC estimated by the current integration method using the SOC estimated by the OCV method.

[0017] The BMU periodically samples the voltage, current, temperature, and SOC of the cells or parallel cell blocks (e.g., every 10 seconds). The BMU transmits battery data, including the voltage, current, temperature, and SOC of the cells or parallel cell blocks, to the ECU via an in-vehicle network. The in-vehicle network can be, for example, a Controller Area Network (CAN) or a Local Interconnect Network (LIN).

[0018] The vehicle speed sensor 27 generates a pulse signal proportional to the rotation speed of the axle and sends it to the ECU. The ECU calculates the vehicle speed and cumulative mileage based on the received pulse signal. The ECU can also obtain the gear position from the shift lever.

[0019] The electric vehicle 20 may be provided with a GPS sensor. The GPS sensor detects the current location (latitude and longitude) and transmits it to the ECU. The ECU can generate a driving history based on the received current location information. The received current location information can also be used to correct the cumulative driving distance.

[0020] The communication unit 26 has a function of performing communication signal processing with the communication unit 33 of the charging stand 30 and a function of performing wireless signal processing for connecting to the network 5. The communication unit 26 can access the network 5 using, for example, a mobile phone network (cellular network), a wireless LAN, Vehicle-to-Infrastructure (V2I), Vehicle-to-Vehicle (V2V), an Electronic Toll Collection System (ETC), or Dedicated Short Range Communications (DSRC).

[0021] The network 5 is a general term for communication paths such as the Internet, dedicated lines, and VPNs (Virtual Private Networks), and the communication media and protocols are not important. Examples of communication media that can be used include a mobile phone network, a wireless LAN, a wired LAN, an optical fiber network, an ADSL network, and a CATV network. Examples of communication protocols that can be used include TCP (Transmission Control Protocol) / IP (Internet Protocol), UDP (User Datagram Protocol) / IP, and Ethernet (registered trademark).

[0022] The ECU may transmit the sampled battery data and vehicle data (e.g., vehicle speed, cumulative mileage, gear position) to the data interpolation system 10 each time, or may store the data in an internal memory and transmit the battery data and vehicle data stored in the memory at a predetermined timing all at once to the data interpolation system 10. Note that when the electric vehicle 20 and the charging stand 30 are connected by a charging cable, the ECU may transmit the battery data and vehicle data stored in the memory to the data interpolation system 10 via the charging stand 30.

[0023] By connecting the electric vehicle 20 to a charging stand 30 with a charging cable, the secondary battery 21 inside the electric vehicle 20 can be charged externally. The charging stand 30 is connected to a commercial power system 2 and charges the secondary battery 21.

[0024] Generally, charging is performed with alternating current (AC) for normal charging and with direct current (DC) for rapid charging. When charging with AC (e.g., single-phase 100 / 200 V), the charging voltage or charging current is controlled by a charger (not shown) inside the electric vehicle 20. When charging with DC, the charging voltage or charging current is controlled by a power supply unit 31 of the charging stand 30. The power supply unit 31 includes a rectifier circuit, a filter, and a DC / DC converter, and generates DC power by full-wave rectifying AC power supplied from the commercial power system 2 using the rectifier circuit and smoothing it using a filter. The DC / DC converter controls the voltage or current of the generated DC power.

[0025] For example, CHAdeMO (registered trademark), ChaoJi, GB / T, and Combo (Combined Charging System) can be used as fast charging standards. CHAdeMO, ChaoJi, and GB / T use CAN as the communication method. Combo uses PLC (Power Line Communication) as the communication method.

[0026] A charging cable that employs the CAN system includes a communication line in addition to a power line. When the charging cable connects the electric vehicle 20 and the charging stand 30, the control unit 25 of the electric vehicle 20 establishes a communication channel with the control unit 32 of the charging stand 30. Note that in a charging cable that employs the PLC system, communication signals are transmitted superimposed on the power line.

[0027] The communication unit 33 of the charging stand 30 has a function of executing communication signal processing with the communication unit 26 of the electric vehicle 20 and a function of executing signal processing for connecting to the network 5. The communication unit 33 can access the network 5 using, for example, a wired LAN, a wireless LAN, or a mobile phone network.

[0028] The data interpolation system 10 includes a control unit 11, a storage unit 12, and a communication unit 13. The communication unit 13 is a communication interface (for example, a network interface card (NIC)) for connecting to the network 5 by wire or wirelessly.

[0029] The control unit 11 includes a data acquisition unit 111, an operation state determination unit 112, a defect determination unit 113, an interpolation method selection unit 114, an interpolation unit 115, and a validity determination unit 116. The functions of the control unit 11 can be realized by a combination of hardware resources and software resources, or by hardware resources alone. Examples of hardware resources that can be used include a CPU, ROM, RAM, GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and other LSIs. Examples of software resources that can be used include programs such as an operating system and applications.

[0030] The storage unit 12 includes a non-volatile recording medium such as an HDD, an SSD, etc., and stores various data. The storage unit 12 includes a battery data storage unit 121 and a vehicle data storage unit 122.

[0031] The data acquisition unit 111 acquires battery data and vehicle data from the electric vehicle 20 or the charging station 30, stores the acquired battery data in the battery data storage unit 121, and stores the acquired vehicle data in the vehicle data storage unit 122. In the following, in this embodiment, it is assumed that the vehicle data related to the operation of the electric vehicle 20 includes time-series data on the vehicle speed and accumulated travel distance. It is assumed that the battery data of the secondary battery 21 includes time-series data on the voltage, current, temperature, and SOC.

[0032] The operating state determination unit 112 determines the operating state of the secondary battery 21 and the operating state of the electric vehicle 20 at each sampling time based on the battery data and vehicle data. The operating state of the vehicle data includes at least an operating state and a stopped state. In the present embodiment, the operating state of the vehicle data is classified into five states: "powered running," "regenerative running," "stopped (IG ON)," "stopped (IG OFF)," and "stationary charging." "Stationary charging" refers to a state in which the vehicle is connected to a charging station 30 and charging. The operating state of the secondary battery 21 includes at least a "charging state," "discharging state," and "stopped state." In the present embodiment, the operating state of the secondary battery 21 is classified into these three states. Hereinafter, a positive current is referred to as a discharging state, a negative current as a charging state, and a current of zero as a stopped state. If data cannot be correctly acquired, an invalid value such as a blank or "FFFF" in hexadecimal is returned, and all invalid values ​​are treated as NaN.

[0033] FIG. 2 shows an example of a condition table for determining the operating state of the electric vehicle 20. When the vehicle speed is a positive value and the current is 0, a positive value, or NaN, the operating state determination unit 112 determines that the operating state of the electric vehicle 20 is powered running. When the vehicle speed is a positive value and the current is a negative value, the operating state determination unit 112 determines that the operating state of the electric vehicle 20 is regenerative running. When the vehicle speed is 0 and the current is a positive value, the operating state determination unit 112 determines that the operating state of the electric vehicle 20 is stopped. When the vehicle speed is 0 and the current is 0, the operating state determination unit 112 determines that the operating state of the electric vehicle 20 is stopped. When the vehicle speed is 0 and the current is a negative value, the operating state determination unit 112 determines that the operating state of the electric vehicle 20 is stopped charging.

[0034] If the vehicle speed is NaN, the current is a positive value or 0, and there is a positive change in the accumulated mileage, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is powered running. If the vehicle speed is NaN, the current is a negative value, and there is a positive change in the accumulated mileage, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is regenerative running. If the vehicle speed is NaN, the current is a positive value, and there is no change in the accumulated mileage, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is stopped. If the vehicle speed is NaN, the current is 0, and there is no change in the accumulated mileage, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is stopped. If the vehicle speed is NaN, the current is a negative value, and there is no change in the accumulated mileage, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is stopped. If the vehicle speed is NaN, the current is a negative value, and there is no change in the accumulated mileage, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is stopped charging.

[0035] If the vehicle speed is 0, the current is NaN, and there is a positive change in the SOC, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is stationary charging. If the vehicle speed is 0, the current is NaN, and there is no change in the SOC, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is resting. If the vehicle speed is 0, the current is NaN, and there is a negative change in the SOC, the operation state determination unit 112 determines that the operation state of the electric vehicle 20 is stationary. Furthermore, if both the current and the vehicle speed are NaN, or if the amount of change in the cumulative mileage or the amount of change in the SOC is an abnormal value (for example, a negative value), the operation state of the electric vehicle 20 is set to the previous value. Note that if sufficient data necessary for state determination cannot be obtained (specifically, if there is no previous value, such as initial data), NaN remains (no state).

[0036] Returning to Fig. 1, the defect determination unit 113 determines whether the battery data includes a defect section. When the amount of change in consecutive data (e.g., timestamp, cumulative mileage, SOC, temperature, etc.) exceeds a predetermined threshold, the defect determination unit 113 determines that the section is a defect section that does not satisfy the specified sampling interval.

[0037] The interpolation method selection unit 114 selects an interpolation method for the battery data of the missing section depending on the operating state of the electric vehicle 20 and the operating state of the secondary battery 21. The interpolation unit 115 uses the selected interpolation method to interpolate the battery data of the missing section based on at least the battery data outside the missing section. For example, the interpolation unit 115 may interpolate the battery data of the missing section based on the battery data outside the missing section and vehicle data.

[0038] The interpolation method selection unit 114 selects an interpolation method according to a combination of state changes of the electric vehicle 20 and the secondary battery 21 before and after the missing section. First, the first interpolation method for current data will be described.

[0039] FIG. 3 is a diagram showing a first specific example of the first interpolation method. The interpolation method selection unit 114 determines that the missing section includes a discharging state if the cumulative mileage immediately after the end of the missing section is greater than the cumulative mileage immediately before the start of the missing section by a predetermined threshold (e.g., 3 km). The interpolation method selection unit 114 checks the operating states of the secondary battery 21 before and after the missing section. In the example shown in FIG. 3, the operating state of the secondary battery 21 before the missing section is discharging, and the operating state of the secondary battery 21 after the missing section is hibernating. In this case, the interpolation method selection unit 114 selects the following first interpolation algorithm:

[0040] The interpolation unit 115 identifies the time at which the SOC reaches its maximum value within a predetermined period (e.g., six hours) going back in time from the start time of the missing section during the discharge period before the missing section. The interpolation unit 115 sets the range from the time at which the SOC reaches its maximum value to the start time of the missing section as the discharge reference section.

[0041] The interpolation unit 115 calculates the decrease value of the SOC in the discharge reference interval. The interpolation unit 115 calculates the decrease value of the SOC per unit time (e.g., 10 seconds) (time gradient of the SOC) based on the decrease value of the SOC in the discharge reference interval and the time of the discharge reference interval. The interpolation unit 115 calculates the increase value of the cumulative mileage per unit time (gradient of the cumulative mileage) based on the increase value of the cumulative mileage in the discharge reference interval and the time of the discharge reference interval. The interpolation unit 115 calculates the decrease value of the SOC per unit distance (e.g., 1 km) (distance gradient of the SOC) based on the time gradient of the SOC and the gradient of the cumulative mileage in the discharge reference interval.

[0042] The interpolation unit 115 calculates the discharge end time within the missing section based on the cumulative mileage at the time immediately before the start of the missing section, the distance gradient of the SOC, and the cumulative mileage at the time immediately after the end of the missing section.The interpolation unit 115 calculates the SOC at the discharge end time within the missing section based on the time when the SOC in the discharge reference section is maximum, the discharge end time within the missing section, the maximum SOC value, and the time gradient of the SOC.The interpolation unit 115 calculates the SOC at the discharge end time within the missing section based on the SOC at the discharge end time within the missing section, the time from the start time of the missing section to the discharge end time within the missing section, and the time gradient of the SOC.

[0043] The interpolation unit 115 calculates an estimated value of the discharge current by dividing the discharge amount corresponding to the difference between the SOC at the start time of the missing section and the SOC at the end time of discharge within the missing section by the time from the start time of the missing section to the end time of discharge within the missing section.

[0044] The interpolation unit 115 interpolates an estimated value of the discharge current (dotted line) as the battery data for each time from the start time of the missing section to the discharge end time within the missing section. The interpolation unit 115 interpolates 0 (dotted line) as the battery data for each time from the discharge end time within the missing section to the end time of the missing section. Note that the interpolation unit 115 may interpolate the cumulative mileage from the start time of the missing section to the discharge end time within the missing section based on the slope of the cumulative mileage in the discharge reference section.

[0045] 4 is a diagram showing a second specific example of the first interpolation method. The interpolation method selection unit 114 checks the operating states of the secondary battery 21 before and after the missing section. In the example shown in FIG. 4, the operating state of the secondary battery 21 before the missing section is a resting state, and the operating state of the secondary battery 21 after the missing section is a discharging state. In this case, the interpolation method selection unit 114 selects the following second interpolation algorithm.

[0046] The interpolation unit 115 identifies the time at which the SOC reaches its minimum value within a predetermined period (e.g., six hours) from the end of the missing section in the discharge period following the missing section. The interpolation unit 115 sets the range from the time at which the SOC reaches its minimum value to the end of the missing section as the discharge reference section.

[0047] The interpolation unit 115 calculates the decrease value of the SOC in the discharge reference interval. The interpolation unit 115 calculates the time gradient of the SOC based on the decrease value of the SOC in the discharge reference interval and the time of the discharge reference interval. The interpolation unit 115 calculates the gradient of the accumulated mileage based on the increase value of the accumulated mileage in the discharge reference interval and the time of the discharge reference interval. The interpolation unit 115 calculates the distance gradient of the SOC based on the time gradient of the SOC and the gradient of the accumulated mileage in the discharge reference interval.

[0048] The interpolation unit 115 calculates the discharge start time within the missing section based on the cumulative mileage at the time immediately after the end of the missing section, the distance gradient of the SOC, and the cumulative mileage at the time immediately before the start of the missing section.The interpolation unit 115 calculates the SOC at the discharge start time within the missing section based on the time when the SOC in the discharge reference section is at its minimum value, the discharge start time within the missing section, the minimum SOC value, and the time gradient of the SOC.The interpolation unit 115 calculates the SOC at the discharge start time within the missing section based on the SOC at the discharge start time within the missing section, the time from the discharge start time within the missing section to the end time of the missing section, and the time gradient of the SOC.

[0049] The interpolation unit 115 calculates an estimated value of the discharge current by dividing the discharge amount corresponding to the difference between the SOC at the discharge start time within the missing section and the SOC at the end time of the missing section by the time from the discharge start time within the missing section to the end time of the missing section. Alternatively, the interpolation unit 115 may simply calculate the estimated value of the discharge current by dividing the discharge amount corresponding to the difference between the SOC at the time immediately before the start of the missing section and the SOC at the time immediately after the end of the missing section, which is included in the battery data, by the time from the discharge start time within the missing section to the end time of the missing section.

[0050] The interpolation unit 115 interpolates an estimated value of the discharge current (dotted line) as the battery data for each time from the discharge start time within the missing section to the end time of the missing section. The interpolation unit 115 interpolates 0 (dotted line) as the battery data for each time from the start time of the missing section to the discharge start time within the missing section. Note that the interpolation unit 115 may interpolate the cumulative mileage from the discharge start time within the missing section to the end time of the missing section based on the slope of the cumulative mileage in the discharge reference section.

[0051] 5 is a diagram showing a third specific example of the first interpolation method. The interpolation method selection unit 114 checks the operating state of the secondary battery 21 before and after the missing section. In the example shown in FIG. 5, the operating state of the secondary battery 21 before the missing section is a discharged state, and the operating state of the secondary battery 21 after the missing section is also a discharged state. In this case, the interpolation method selection unit 114 selects the following third interpolation algorithm.

[0052] The interpolation unit 115 calculates an estimated value of the discharge current by dividing the discharge amount corresponding to the difference in SOC between the time immediately before the start of the missing section and the time immediately after the end of the missing section by the duration of the missing section. The interpolation unit 115 interpolates an estimated value of the discharge current (dotted line) as battery data for each time from the start time of the missing section to the end time of the missing section. Alternatively, the interpolation unit 115 may simply calculate an estimated value of the discharge current by dividing the discharge amount corresponding to the difference in SOC between the time immediately before the start of the missing section and the time immediately after the end of the missing section, which is included in the battery data, by the time from the start time of the missing section to the end time of discharge within the missing section. Alternatively, the discharge current may be estimated based on the average current value of the discharge reference section, or may be estimated from past driving data using machine learning or the like.

[0053] The interpolation method selection unit 114 may select the first interpolation algorithm instead of the third interpolation algorithm. When the first interpolation algorithm is applied to the third specific example, it is not necessary to calculate the discharge end time within the missing section. The interpolation unit 115 calculates the SOC at the end time of the missing section based on the time when the SOC in the discharge reference section is at its maximum value, the end time of the missing section, the maximum SOC value, and the time gradient of the SOC. The interpolation unit 115 calculates the SOC at the start time of the missing section based on the SOC at the end time of the missing section, the duration of the missing section, and the time gradient of the SOC. The subsequent processing is the same as in the first specific example.

[0054] The interpolation method selection unit 114 may select the second interpolation algorithm. When the second interpolation algorithm is applied to the third specific example, it is not necessary to calculate the discharge start time within the missing section. The interpolation unit 115 calculates the SOC at the start time of the missing section based on the time when the SOC in the discharge reference section is at its minimum value, the start time of the missing section, the minimum SOC value, and the time gradient of the SOC. The interpolation unit 115 calculates the SOC at the end time of the missing section based on the SOC at the start time of the missing section, the duration of the missing section, and the time gradient of the SOC. The subsequent processing is the same as in the second specific example.

[0055] 6 is a flowchart showing the flow of basic operations of the data interpolation system 10 according to the embodiment. The data acquisition unit 111 acquires battery data and vehicle data from the electric vehicle 20 or the charging station 30 (S10). The operating state determination unit 112 determines the operating state of the secondary battery 21 and the operating state of the electric vehicle 20 at each sampling time based on the battery data and vehicle data (S20). The missing data determination unit 113 determines whether the current data included in the battery data contains a missing section (S30). If the current data contains a missing section (Y in S30), the interpolation method selection unit 114 and the interpolation unit 115 perform data interpolation processing for the missing section (S40). If the current data does not contain a missing section (N in S30), the interpolation processing of step S40 is skipped.

[0056] 7 shows an example of interpolation processing using the first interpolation method of the data interpolation system 10 according to the embodiment. The subroutine flowchart shown in FIG. 7 is based on the assumption that the electric vehicle 20 is not in a dormant state. The interpolation method selection unit 114 determines whether the state of the secondary battery 21 after the missing section is State A (S41). If the state of the secondary battery 21 after the missing section is State A (Y in S41), the interpolation method selection unit 114 determines whether the state of the secondary battery 21 before the missing section is State A (S42).

[0057] If the state of the secondary battery 21 before the missing section and the state of the secondary battery 21 after the missing section are state A (Y in S42), the interpolation method selection unit 114 selects a method of interpolating from battery data before and after the missing section. If state A is a discharged state, the interpolation unit 115 references the battery data before and after the missing section and linearly interpolates the battery data of the missing section from the battery data before and after so as to maintain continuity with the discharged states before and after (S43). If state A is a charged state, the interpolation unit 115 references the battery data before and after the missing section and linearly interpolates the battery data of the missing section from the battery data before and after so as to maintain continuity with the charged states before and after (S43).

[0058] If the state of the secondary battery 21 before the missing section is not State A, but the state of the secondary battery 21 after the missing section is State A (N in S42), the interpolation method selection unit 114 selects a method of interpolating from the battery data after the missing section. If State A is a discharging state and the state changes from a dormant state to a discharging state before and after the missing section, the interpolation unit 115 references the battery data after the missing section and interpolates the battery data of the missing section from the subsequent battery data so as to maintain continuity with the immediately subsequent discharging state (S44). If State A is a charging state and the state changes from a dormant state to a charging state before and after the missing section, the interpolation unit 115 references the battery data after the missing section and interpolates the battery data of the missing section from the subsequent battery data so as to maintain continuity with the immediately subsequent charging state (S44).

[0059] If the state of the secondary battery 21 after the missing section is not State A (N in S41), the interpolation method selection unit 114 determines whether the state of the secondary battery 21 before the missing section is State A (S45). If the state of the secondary battery 21 before the missing section is State A and the state of the secondary battery 21 after the missing section is not State A (Y in S45), the interpolation method selection unit 114 selects a method of interpolating from the battery data before the missing section. If State A is a discharging state and changes from the discharging state to a dormant state before and after the missing section, the interpolation unit 115 references the battery data before the missing section and interpolates the battery data for the missing section from the preceding battery data so as to maintain continuity with the immediately preceding discharging state (S46). If State A is a charging state and changes from the charging state to a dormant state before and after the missing section, the interpolation unit 115 references the battery data before the missing section and interpolates the battery data for the missing section from the preceding battery data so as to maintain continuity with the immediately preceding charging state (S46).

[0060] If the state of the secondary battery 21 before the missing section and the state of the secondary battery 21 after the missing section are not state A (N in S45), the battery data for the missing section is unrelated to the discharge state or charge state, and the interpolation process is skipped.

[0061] In step S42, if the state of the secondary battery 21 before the missing section and the state of the secondary battery 21 after the missing section are state A (Y in S42), the interpolation method selection unit 114 may select a method of interpolating from the battery data before the missing section. In this case, the interpolation unit 115 refers to the battery data before the missing section and interpolates the battery data of the missing section from the preceding battery data so as to maintain continuity with state A immediately before.

[0062] When the operating state of electric vehicle 20 is in a resting state and at least one of secondary batteries 21 before and after the missing section is in a discharging state, interpolation method selection unit 114 skips the interpolation process. When the state changes from a resting state to a charging state before and after the missing section, interpolation unit 115 references battery data after the missing section and interpolates the battery data of the missing section from the subsequent battery data so as to maintain continuity with the immediately subsequent charging state. When the state changes from a charging state to a resting state before and after the missing section, interpolation unit 115 references battery data before the missing section and interpolates the battery data of the missing section from the preceding battery data so as to maintain continuity with the immediately preceding charging state.

[0063] When the states of the secondary battery 21 before and after the missing section are both in a charged state, the interpolation unit 115 refers to the battery data before and after the missing section and linearly interpolates the battery data of the missing section from the battery data before and after so as to maintain continuity with the charged state before and after. Note that the interpolation unit 115 may also refer to the battery data before the missing section and interpolate the battery data of the missing section from the preceding battery data so as to maintain continuity with the immediately preceding charged state.

[0064] Next, the second interpolation method will be described. The second interpolation method is effective when at least one of the secondary batteries 21 before and after the missing section is in a charged state. This interpolation method is particularly effective when the secondary batteries 21 before and after the missing section are in a charged state.

[0065] In the second interpolation method, when at least one of the sections before and after the missing section is in a charged state, the interpolation unit 115 interpolates the current data of the missing section so that the discharge amount and the charge amount correspond to each other during a charge / discharge period from the SOC in the charged state immediately after the missing section to an SOC corresponding to the SOC in the past direction. Alternatively, when at least one of the sections before and after the missing section is in a charged state, the interpolation unit 115 interpolates the current data of the missing section so that the discharge amount and the charge amount correspond to each other during a charge / discharge period from the SOC in the charged state immediately before the missing section to an SOC corresponding to the SOC in the future direction.

[0066] The validity determination unit 116 determines the validity of the interpolation process based on the charge amount or charge time of the missing section based on the difference between the discharge amount and the charge amount calculated from the battery data included in the charge / discharge period.

[0067] FIG. 8 is a diagram showing a first specific example of the second interpolation method. In the second interpolation method, the charge state of the secondary battery 21 is set to a charge state when the electric vehicle 20 is stopped and charging. The interpolation method selection unit 114 checks the operating states of the secondary battery 21 before and after the missing section. In the example shown in FIG. 8, the operating state of the secondary battery 21 before the missing section is a charging state, and the operating state of the secondary battery 21 after the missing section is also a charging state. In this case, the interpolation method selection unit 114 selects the following fourth interpolation algorithm.

[0068] The interpolation unit 115 identifies, in the past direction from the end time of the missing section, the time immediately preceding the end time of the missing section at which the SOC is the same as the SOC at the time immediately after the end of the missing section. The interpolation unit 115 sets the range from the most recent time at which the SOC is the same to the end time of the missing section as the charge / discharge reference section. The interpolation unit 115 integrates positive current values ​​within the charge / discharge reference section to calculate the integrated discharge amount (1), and integrates negative current values ​​within the charge / discharge reference section to calculate the integrated charge amount (2). The interpolation unit 115 subtracts the integrated charge amount (2) from the integrated discharge amount (1) to calculate the missing charge amount (3).

[0069] The interpolation unit 115 identifies the maximum value (4) of the charging current (the minimum value as current data) within a predetermined period (e.g., 24 hours) from the end time of the missing section toward the future. The interpolation unit 115 may also identify the maximum value (4) of the charging current within the charge / discharge reference section. The interpolation unit 115 may also identify the maximum value (4) of the charging current within both the charge / discharge reference section and the predetermined period from the end time of the missing section toward the future.

[0070] The interpolation unit 115 divides the missing charge amount (3) by the duration of the missing section to calculate the estimated value of the charging current (5) for the missing section. The interpolation unit 115 interpolates the estimated value of the charging current (5) (dotted line) as the battery data for each time from the start time to the end time of the missing section.

[0071] 9 is a diagram showing a second specific example of the second interpolation method. The interpolation method selection unit 114 checks the operating states of the secondary battery 21 before and after the missing section. In the example shown in FIG. 9, the operating state of the secondary battery 21 before the missing section is a discharging state, and the operating state of the secondary battery 21 after the missing section is a charging state. In this case, the interpolation method selection unit 114 selects the following fifth interpolation algorithm.

[0072] The interpolation unit 115 identifies the time immediately preceding the end of the missing section, in the past direction from the end of the missing section, at which the SOC is the same as the SOC at the time immediately after the end of the missing section. The interpolation unit 115 sets the range from the most recent time at which the SOC is the same to the end of the missing section as the charge / discharge reference section. The interpolation unit 115 calculates the integrated discharge amount (1) by integrating positive current values ​​within the charge / discharge reference section. In the second specific example, the integrated charge amount (2) within the charge / discharge reference section is set to 0.

[0073] The interpolation unit 115 identifies the maximum value (4) of the charging current (the minimum value as current data) within a predetermined period (e.g., 24 hours) from the end time of the missing section toward the future. The interpolation unit 115 may also identify the maximum value (4) of the charging current within the charge / discharge reference section. The interpolation unit 115 may also identify the maximum value (4) of the charging current within both the charge / discharge reference section and the predetermined period from the end time of the missing section toward the future.

[0074] The interpolation unit 115 calculates the charging time within the missing section by dividing the missing charge amount (= cumulative discharge amount (1) - 0) by the maximum value of the charging current (4). The interpolation unit 115 sets the charging time within the missing section in the past from the end time of the missing section, and sets the retroactive time as the charging start time within the missing section. The interpolation unit 115 interpolates the maximum value of the charging current (4) (dotted line) as the battery data for each time from the charging start time within the missing section to the end time of the missing section. The interpolation unit 115 interpolates 0 (dotted line) as the battery data for each time from the start time of the missing section to the charging start time within the missing section.

[0075] 10 is a diagram showing a third specific example of the second interpolation method. The interpolation method selection unit 114 checks the operating states of the secondary battery 21 before and after the missing section. In the example shown in FIG. 10, the operating state of the secondary battery 21 before the missing section is a charging state, and the operating state of the secondary battery 21 after the missing section is a discharging state. In this case, the interpolation method selection unit 114 selects the following sixth interpolation algorithm.

[0076] The interpolation unit 115 identifies the time immediately preceding the start time of the missing section, in the future direction from the start time of the missing section, at which the SOC is the same as the SOC at the time immediately before the start of the missing section. The interpolation unit 115 sets the range from the most recent time at which the SOC is the same to the start time of the missing section as the charge / discharge reference section. The interpolation unit 115 calculates the integrated discharge amount (1) by integrating positive current values ​​within the charge / discharge reference section. In the third specific example, the integrated charge amount (2) within the charge / discharge reference section is set to 0.

[0077] The interpolation unit 115 identifies the maximum value (4) of the charging current (the minimum value as current data) within a predetermined period (e.g., 24 hours) from the start time of the missing section toward the past. The interpolation unit 115 may also identify the maximum value (4) of the charging current within the charge / discharge reference section. The interpolation unit 115 may also identify the maximum value (4) of the charging current within both the charge / discharge reference section and the predetermined period from the start time of the missing section toward the past.

[0078] The interpolation unit 115 calculates the charging time within the missing section by dividing the missing charge amount (= cumulative discharge amount (1) - 0) by the maximum value of the charging current (4). The interpolation unit 115 sets the charging time within the missing section in the future from the start time of the missing section, and sets the advanced time as the charging end time within the missing section. The interpolation unit 115 interpolates the maximum value of the charging current (4) (dotted line) as the battery data for each time from the start time of the missing section to the charging end time within the missing section. The interpolation unit 115 interpolates 0 (dotted line) as the battery data for each time from the charging end time within the missing section to the end time of the missing section.

[0079] 11 shows an example of interpolation processing using the second interpolation method of the data interpolation system 10 according to the embodiment. The interpolation method selection unit 114 determines whether the secondary battery 21 is in a charged state after the missing section (S410). If the secondary battery 21 is in a charged state after the missing section (Y in S410), the interpolation method selection unit 114 determines whether the secondary battery 21 was in a charged state before the missing section (S411).

[0080] If the state of the secondary battery 21 before and after the missing section is the charging state (Y in S411), the interpolation unit 115 sets the range from the SOC at the time immediately after the end of the missing section to the SOC that becomes the same in the past as the charge / discharge reference period of one cycle. The interpolation unit 115 obtains the maximum value (4) of the charge current from within the charge / discharge reference period of one cycle (S412). In the flowchart of FIG. 11, the maximum value (4) of the charge current is an absolute value.

[0081] The interpolation unit 115 calculates the deficit charge amount (3) by subtracting the cumulative charge amount (2) from the cumulative discharge amount (1) within the charge / discharge reference section (S413). The interpolation unit 115 calculates the estimated value of the charging current (5) by dividing the cumulative charge amount (3) by the duration of the deficit section (S414). In the flowchart of FIG. 11, the estimated value of the charging current (5) is an absolute value.

[0082] The validity determination unit 116 compares the estimated value (5) of the charging current with the maximum value (4) of the charging current (S415). If the estimated value (5) of the charging current is equal to or less than the maximum value (4) of the charging current (Y in S415), the interpolation unit 115 interpolates the estimated value (5) of the charging current into the missing section (S416). If the estimated value (5) of the charging current exceeds the maximum value (4) of the charging current (N in S415), the validity determination unit 116 determines that the interpolated current value is inappropriate and skips the interpolation process.

[0083] If the secondary battery 21 is in a discharging state or a resting state before the missing section and in a charging state after the missing section (N in S411), the interpolation unit 115 sets the range from the SOC at the time immediately after the end of the missing section to the SOC that is the same in the past as the SOC at the time immediately after the end of the missing section as the charge / discharge reference period of one cycle. The interpolation unit 115 obtains the maximum value (4) of the charge current from within the charge / discharge reference period of one cycle (S417).

[0084] The interpolation unit 115 calculates the deficit charge amount (3) by subtracting the cumulative charge amount (2) from the cumulative discharge amount (1) within the charge / discharge reference section (S418). The interpolation unit 115 divides the deficit charge amount (3) by the maximum value of the charging current (4) to calculate the charging time within the deficit section (S419).

[0085] The validity determination unit 116 compares the charging time within the missing section with the total time for the missing section (S420). If the charging time within the missing section is less than or equal to the total time for the missing section (Y in S420), the interpolation unit 115 interpolates the maximum value of the charging current (4) for the missing section (S421). If the charging time within the missing section exceeds the total time for the missing section (N in S420), the validity determination unit 116 determines that the charging time within the missing section is inappropriate and skips the interpolation process.

[0086] If the secondary battery 21 is not in a charging state after the missing section (N in S410), the interpolation method selection unit 114 determines whether the secondary battery 21 is in a charging state before the missing section (S421). If the secondary battery 21 is in a discharging state or a resting state before the missing section and is in a charging state after the missing section (Y in S421), the interpolation unit 115 sets the range from the SOC at the time immediately before the start of the missing section to the SOC that will be the same in the future as the charge / discharge reference period of one cycle. The interpolation unit 115 obtains the maximum value (4) of the charge current from within the charge / discharge reference period of one cycle (S422).

[0087] The interpolation unit 115 calculates the deficit charge amount (3) by subtracting the cumulative charge amount (2) from the cumulative discharge amount (1) within the charge / discharge reference section (S423). The interpolation unit 115 calculates the charge time within the deficit section by dividing the deficit charge amount (3) by the maximum value of the charging current (4) (S424).

[0088] The validity determination unit 116 compares the charging time within the missing section with the total time for the missing section (S425). If the charging time within the missing section is less than or equal to the total time for the missing section (Y in S425), the interpolation unit 115 interpolates the maximum value of the charging current (4) for the missing section (S426). If the charging time within the missing section exceeds the total time for the missing section (N in S425), the validity determination unit 116 determines that the charging time within the missing section is inappropriate and skips the interpolation process.

[0089] If the state of the secondary battery 21 before the missing section and the state of the secondary battery 21 after the missing section are not in a charged state (N in S421), the battery data for the missing section is irrelevant to the charged state, and the interpolation process is skipped.

[0090] In the above steps S413, S418, and S423, if the calculated integrated discharge amount (1) or integrated charge amount (2) within the charge / discharge reference interval exceeds the rated capacity of the secondary battery 21, the validity determination unit 116 may determine that the interpolation process is inappropriate and skip subsequent interpolation processes. The rated capacity of the secondary battery 21 is the current full charge capacity, and the current full charge capacity is calculated by multiplying the initial full charge capacity by the SOH (State Of Health).

[0091] 12(a)-(b) are diagrams illustrating an example of estimating the SOC of a missing section. The example shown in FIG. 12(a) is an example in which the missing section includes two charge / discharge cycles. In the second interpolation method described above, the missing section is recognized as one charge / discharge cycle. Therefore, the transition of the SOC due to the charge / discharge of the missing section is recognized as shown in FIG. 12(b). In this case, the SOC falls below 0% due to the discharge of the missing section. This results in inappropriate interpolation processing. By comparing the discharge amount or charge amount within the charge / discharge reference section with the rated capacity of the secondary battery 21, inappropriate interpolation processing can be avoided.

[0092] In the above steps S413, S418, and S423, if the calculated cumulative charge amount (2) within the charge / discharge reference interval exceeds the cumulative discharge amount (1), the validity determination unit 116 may determine that the interpolation process is inappropriate and skip subsequent interpolation processes.

[0093] In the above description, the interpolation method selection unit 114 may first interpolate the current data in the discharging state of the missing section using a first interpolation method, and then interpolate the current data in the charging state of the missing section using a second interpolation method.

[0094] As described above, according to this embodiment, the usefulness of the battery data can be improved by interpolating missing sections of the battery data with high accuracy. In the first interpolation method, by changing the interpolation method depending on the operating state of the electric vehicle 20, inappropriate interpolation can be avoided and the accuracy of the interpolated data can be improved.

[0095] The second interpolation method uses the SOC relatively, thereby eliminating the influence of SOC error and rated capacity that occur due to deterioration of the secondary battery 21. Specifically, the shape of the SOC-OCV curve of the secondary battery 21 changes due to deterioration. In a method that calculates the charge amount of the missing section by calculating the difference in SOC based on the OCV measured immediately before the start and immediately after the end of the missing section and multiplying the rated capacity of the secondary battery 21 by this SOC difference, errors due to the influence of the SOC error and rated capacity become large.

[0096] Furthermore, the current sensor 23 has a measurement error, and this measurement error is also accumulated in the charge amount calculated by integrating the current. The longer the data, the greater the measurement error. In this regard, the second interpolation method uses the difference between the discharge amount and the charge amount during the charge / discharge reference period, thereby offsetting the measurement error of discharge and charge. The measurement error is limited to the missing section.

[0097] In particular, when the secondary battery 21 is in a charged state before and after the missing section, selecting the second interpolation method allows for highly accurate interpolation. Furthermore, by determining the validity of the charging current value to be interpolated, it is possible to avoid performing low-accuracy interpolation processing, thereby ensuring the accuracy of the interpolation processing.

[0098] The present disclosure has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0099] The data interpolation system 10 described above may be implemented in the control unit 25 of the electric vehicle 20 or the control unit 32 of the charging station 30 .

[0100] In the above embodiment, the electric vehicle 20 is assumed to be a four-wheeled electric vehicle. In this regard, it may also be an electric motorcycle (electric scooter), an electric bicycle, or an electric kick scooter. Furthermore, electric vehicles include not only full-scale electric vehicles but also low-speed electric vehicles such as golf carts and land cars. Furthermore, the device in which the secondary battery 21 is mounted is not limited to the electric vehicle 20. Devices in which the secondary battery 21 is mounted include electric vehicles such as electric ships, railcars, and multicopters (drones), stationary energy storage systems, and consumer electronic devices (smartphones, notebook PCs, etc.). Note that when the secondary battery 21 is mounted in a stationary energy storage system or consumer electronic device, the operating state of the device does not include a regenerative charging state.

[0101] The embodiment may be specified by the following items.

[0102] [Item 1] A data interpolation system (10) comprising: a data acquisition unit (111) that acquires battery data including at least time-series data of current and SOC (State of Charge), a defect determination unit (113) that determines whether the battery data includes a missing section, and an interpolation unit (115) that interpolates battery data for the missing section based on at least battery data other than the missing section, wherein, when at least one of the sections before and after the missing section is in a charged state, the interpolation unit (115) interpolates current data for the missing section so that a discharge amount corresponds to a charge amount during a charge / discharge period from an SOC in a charged state immediately after the missing section to a corresponding SOC in the past direction, or during a charge / discharge period from an SOC in a charged state immediately before the missing section to a corresponding SOC in the future direction. This allows the missing section of battery data to be interpolated with high accuracy. [Item 2] The data interpolation system (10) according to Item 1 further includes a validity determination unit (116) that determines the validity of the interpolation process based on the charge amount or charge time of the missing section, which is based on the difference between the discharge amount and the charge amount calculated from battery data included in the charge / discharge period. This makes it possible to avoid inappropriate interpolation. [Item 3] The data interpolation system (10) according to Item 2, wherein the validity determination unit (116) determines that the interpolation process is inappropriate if the discharge amount or the charge amount during the charge / discharge period exceeds the rated capacity of the battery (21). This makes it possible to avoid inappropriate interpolation. [Item 4] The data interpolation system (10) according to Item 2, wherein the validity determination unit (116) determines that the interpolation process is inappropriate if the charge amount during the charge / discharge period exceeds the discharge amount. This makes it possible to avoid inappropriate interpolation. [Item 5] The data interpolation system (10) according to Item 2, characterized in that the validity determination unit (116) determines that the interpolation process is inappropriate when the estimated value of the charging current obtained from the capacity difference and the duration of the missing section is greater than the maximum value of the charging current in the charging period before or after the missing section. This makes it possible to avoid inappropriate interpolation.[Item 6] A data interpolation method comprising the steps of: acquiring battery data including at least time-series data of current and SOC (State Of Charge), determining whether the battery data includes a missing section, and interpolating battery data for the missing section based on at least battery data other than the missing section, wherein, when at least one of the sections before and after the missing section is in a charged state, the interpolating step interpolates current data for the missing section so that the discharge amount corresponds to the charge amount during a charge / discharge period from the SOC in the charged state immediately after the missing section to the corresponding SOC in the past, or during a charge / discharge period from the SOC in the charged state immediately before the missing section to the corresponding SOC in the future. This allows the missing section of battery data to be interpolated with high accuracy. [Item 7] A data interpolation program that causes a computer to execute the following steps: acquiring battery data including at least time-series data of current and SOC (State Of Charge), determining whether the battery data includes a missing section, and interpolating battery data for the missing section based on at least battery data other than the missing section, wherein, when at least one of the sections before and after the missing section is in a charged state, the interpolation interpolates current data for the missing section so that the discharge amount corresponds to the charge amount during a charge / discharge period from an SOC in a charged state immediately after the missing section to a corresponding SOC in the past, or during a charge / discharge period from an SOC in a charged state immediately before the missing section to a corresponding SOC in the future. This allows the missing section of battery data to be interpolated with high accuracy.

[0103] The present disclosure can be used in a battery analysis system built on a cloud server.

[0104] 2 Commercial power system, 5 Network, 10 Data interpolation system, 11 Control unit, 12 Memory unit, 13 Communication unit, 20 Electric vehicle, 21 Secondary battery, 22 Voltage sensor, 23 Current sensor, 24 Temperature sensor, 25 Control unit, 26 Communication unit, 27 Vehicle speed sensor, 30 Charging stand, 31 Power supply unit, 32 Control unit, 33 Communication unit, 111 Data acquisition unit, 112 Operation state determination unit, 113 Missing data determination unit, 114 Interpolation method selection unit, 115 Interpolation unit, 116 Validity determination unit, 121 Battery data storage unit, 122 Vehicle data storage unit.

Claims

1. a data acquisition unit that acquires battery data including at least time series data of current and SOC (State Of Charge); a loss determination unit that determines whether the battery data includes a loss section; an interpolation unit that interpolates battery data of the missing section based on battery data of at least a section other than the missing section, a data interpolation system characterized in that, when at least one of before and after the missing section is in a charged state, the interpolation unit interpolates current data of the missing section so that a discharge amount corresponds to a charge amount during a charge / discharge period from an SOC in a charged state immediately after the missing section to a corresponding SOC in a past direction, or during a charge / discharge period from an SOC in a charged state immediately before the missing section to a corresponding SOC in a future direction.

2. The data interpolation system according to claim 1, further comprising a validity determination unit that determines the validity of the interpolation process based on the charge amount or charge time of the missing section, which is based on a capacity difference between the discharge amount and the charge amount calculated from battery data included in the charge and discharge period.

3. 3. The data interpolation system according to claim 2, wherein the validity determining unit determines that the interpolation process is inappropriate when the discharge amount or the charge amount during the charge / discharge period exceeds a rated capacity of the battery.

4. 3. The data interpolation system according to claim 2, wherein the validity determining unit determines that the interpolation process is inappropriate when the charge amount during the charge / discharge period exceeds the discharge amount.

5. The data interpolation system according to claim 2, characterized in that the validity determination unit determines that the interpolation process is inappropriate when the estimated value of the charging current obtained from the capacity difference and the time of the missing section is greater than the maximum value of the charging current in the charging period before or after the missing section.

6. acquiring battery data including at least time series data of current and SOC (State Of Charge); determining whether the battery data includes a missing section; and interpolating battery data of the missing section based on battery data of at least a section other than the missing section, The data interpolation method is characterized in that, when at least one of before and after the missing section is in a charged state, the interpolating step interpolates current data of the missing section so that a discharge amount corresponds to a charge amount during a charge / discharge period from an SOC in a charged state immediately after the missing section to a corresponding SOC in a past direction, or during a charge / discharge period from an SOC in a charged state immediately before the missing section to a corresponding SOC in a future direction.

7. A process of acquiring battery data including at least time series data of current and SOC (State Of Charge); A process of determining whether the battery data includes a missing section; and executing a process of interpolating battery data of the missing section based on battery data of at least sections other than the missing section. The data interpolation program is characterized in that the interpolation process, when at least one of before and after the missing section is in a charged state, interpolates current data of the missing section so that a discharge amount corresponds to a charge amount during a charge / discharge period from an SOC in a charged state immediately after the missing section to a corresponding SOC in a past direction, or during a charge / discharge period from an SOC in a charged state immediately before the missing section to a corresponding SOC in a future direction.