Battery management system, battery management method, battery management program, and recording medium

Abstract

In the present invention, a measurement data acquisition unit (251) acquires, from sensors (22, 23, 24) in a battery pack (20) and at a predetermined sampling period, measurement data of at least one of voltage, current, and temperature. A data transmission unit (256) transmits the acquired measurement data to the outside via a network (5) in a first transmission period. A change amount detection unit (254) determines whether or not a current change amount between a current value and a previous value in the first transmission period of the measurement data has changed by a set ratio or more from a previous change amount between the previous value and the value therebefore? When a change by the set ratio or more is detected, the data transmission unit (256) transmits measurement data of a section between the previous value and the current value in a second transmission period which is narrower than the first transmission period.

Description

Battery management system, battery management method, battery management program, and recording medium

[0001] The present disclosure relates to a battery management system, a battery management method, a battery management program, and a recording medium that transmits battery measurement data.

[0002] A battery analysis system has been put into practical use. This system stores battery data (such as voltage, current, and temperature) measured by a battery management system (BMS) in a battery pack installed in an electric vehicle in a cloud database and analyzes the status of the battery pack installed in the electric vehicle. If the battery data is transmitted to a cloud server at the same frequency as measured by the BMS, the amount of communication data, the amount of processing and the amount of data stored on the cloud server increase, resulting in high analysis costs. Furthermore, if the measured battery data is simply thinned out before transmission, the reproducibility of the waveform of the measured battery data decreases, and the analysis accuracy of the battery analysis system decreases.

[0003] Regarding sensing value transmission technology, Patent Document 1 discloses a method in which the transmitting hardware determines whether or not there has been a change in sensing information, and transmits the sensing value only when the sensing value has changed. With this method, if the measurement cycle is short, the amount of calculation on the transmitting hardware increases, and if the measurement cycle is long, the reproducibility of the waveform on the receiving hardware decreases.

[0004] Japanese Patent Application Laid-Open No. 2004-302765

[0005] The present disclosure has been made in consideration of these circumstances, and its purpose is to provide a technology that can reduce the amount of data transmitted from a battery pack while improving the waveform reproducibility of measurement data on the receiving side.

[0006] In order to solve the above problem, a battery management system according to one aspect of the present disclosure includes a measurement data acquisition unit that acquires at least one of measurement data of voltage, current, and temperature from a sensor in a battery pack at a predetermined sampling period, a data transmission unit that transmits the acquired measurement data to an external device via a network at a first transmission period, and a change amount detection unit that determines whether a current change amount between a previous value and a current value of the measurement data in the first transmission period has changed by more than a set ratio compared to a previous change amount between a value before last and the previous value. If a change of more than the set ratio is detected, the data transmission unit transmits the measurement data for the section between the previous value and the current value at a second transmission period that is shorter than the first transmission period.

[0007] 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.

[0008] According to the present disclosure, it is possible to reduce the amount of data transmitted from a battery pack while improving the waveform reproducibility of measurement data on the receiving side.

[0009] 5 is a diagram illustrating an electric vehicle equipped with a battery pack having a BMS according to an embodiment, and a battery analysis system. FIG. 2A is a diagram illustrating a configuration of a battery pack system including a plurality of unit cells connected in series. FIG. 2B is a diagram illustrating a configuration of a battery pack system including a plurality of cell blocks connected in series. FIG. 5 is a diagram illustrating an example configuration of a BMS. FIG. 4A is a diagram illustrating a specific example of a transmission cycle of measurement data according to a comparative example. FIG. 4B is a diagram illustrating a specific example of a restored waveform in a battery analysis system corresponding to FIG. 4A. FIG. 5 is a diagram illustrating a specific example of a transmission cycle of measurement data according to an embodiment. FIG. 5 is a diagram illustrating a specific example of a restored waveform in a battery analysis system corresponding to FIG. 5. FIG. 6 is a flowchart illustrating a first example of transmission processing of measurement data by a BMS according to an embodiment. FIG. 6 is a flowchart illustrating a second example of transmission processing of measurement data by a BMS according to an embodiment.

[0010] FIG. 1 is a diagram illustrating an electric vehicle 1 equipped with a battery pack 20 equipped with a BMS 25 according to an embodiment, and a battery analysis system 10. The battery analysis system 10 is a system for analyzing the state of the battery pack 20 installed in the electric vehicle 1. In this embodiment, the battery analysis system 10 is built on a cloud server installed in a data center managed by a cloud service provider. A battery analysis service provider that provides an analysis service for the battery pack 20 installed in the electric vehicle 1 uses the cloud server by entering into a contract with the cloud service provider. The battery analysis system 10 may also be built on the battery analysis service provider's own server installed in its own facility or data center.

[0011] An assembled battery system 21 included in a battery pack 20 mounted on the electric vehicle 1 supplies power to a drive motor (not shown). The assembled battery system 21 includes a plurality of unit cells or a plurality of cell blocks connected in series. In the case of a battery pack 20 with a large number of cells connected in series, the assembled battery system 21 may be configured by connecting in series a plurality of battery modules, each of which includes a plurality of unit cells or a plurality of cell blocks connected in series.

[0012] 2A is a diagram showing the configuration of a battery pack system 21 including a plurality of unit cells E1-Em connected in series. FIG. 2B is a diagram showing the configuration of a battery pack system 21 including a plurality of cell blocks Eb1-Ebm connected in series. Each cell block Eb1-Ebm includes a plurality of unit cells E1a-E1n-Ema-Emn connected in parallel.

[0013] The cells may be lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, or the like. Hereinafter, this specification will assume an example in which lithium-ion battery cells (nominal voltage: 3.6-3.7V) are used. The number of unit cells or cell blocks connected in series is determined according to the voltage of the drive motor. For example, when the number of series connections is large, the system configuration shown in FIG. 2A or 2B is treated as a single battery module, and multiple battery modules are connected in series to form battery pack system 21.

[0014] The voltage sensor 22 detects the voltage across each of the multiple series-connected unit cells E1-Em or cell blocks Eb1-Ebm. A shunt resistor is connected in series with the multiple series-connected unit cells E1-Em or cell blocks Eb1-Ebm. The current sensor 23 detects the current flowing through the series-connected unit cells E1-Em or cell blocks Eb1-Ebm based on the voltage across the shunt resistor. Note that a Hall element may be used instead of the shunt resistor. The temperature sensors 24 are installed at multiple observation points within the battery pack 20 including the assembled battery system 21. For example, thermistors T1-Tm are used as the temperature sensors 24, and are installed at multiple locations on the surface of the assembled battery system 21 as shown in FIG. 2A or 2B .

[0015] The BMS 25 transmits measurement data of the voltage, current, and temperature measured by the voltage sensor 22, current sensor 23, and temperature sensor 24, respectively, to an ECU (Electronic Control Unit) (not shown) via an in-vehicle network. A communication unit 26 provided in the ECU executes 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, V2I (Vehicle to Infrastructure), V2V (Vehicle to Vehicle), an ETC system (Electronic Toll Collection System), or DSRC (Dedicated Short Range Communications).

[0016] The network 5 is a general term for communication paths such as the Internet, a dedicated line, and a virtual private network (VPN), and the communication medium and protocol 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).

[0017] 3 is a diagram showing an example of the configuration of the BMS 25. The BMS 25 includes a measurement data acquisition unit 251, a smoothing processing unit 252, a working memory 253, a change amount detection unit 254, a transmission cycle setting unit 255, and a data transmission unit 256. In this embodiment, attention is focused on the function of transmitting measurement data from the BMS 25 to the battery analysis system 10, and therefore only functions related to the measurement data transmission function are depicted as functional blocks of the BMS 25 in FIG.

[0018] The functions of the BMS 25 can be realized by a combination of hardware and software resources, or by hardware resources alone. Hardware resources include a CPU, ROM, RAM, GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and other LSIs. Software resources include programs such as firmware.

[0019] The measurement data acquisition unit 251 acquires measurement data of voltage, current, and temperature from the voltage sensor 22, current sensor 23, and temperature sensor 24 in the battery pack 20 at a predetermined sampling period.

[0020] The smoothing processing unit 252 smoothes the measurement data of voltage, current, and temperature acquired in time series by the measurement data acquisition unit 251 from the voltage sensor 22, current sensor 23, and temperature sensor 24, and stores the smoothed measurement data in the working memory 253 at a predetermined storage period. The working memory 253 can be configured, for example, as a ring buffer. The smoothing processing unit 252 calculates, for example, a moving average value or a moving median value over a predetermined period and performs the smoothing process. The storage period is set to a period longer than the sampling period and shorter than the first transmission period. In the following description of the present embodiment, an example is assumed in which the sampling period is 100 ms, the storage period is 1 s (second), and the first transmission period is 10 s (second).

[0021] The smoothing processing unit 252 may thin out the measurement data acquired at the sampling period at the storage period, and store the instantaneous values ​​of the acquired measurement data in the working memory 253 as they are.

[0022] The voltage measurement data stored in working memory 253 as measurement data of voltage to be transmitted may be the cell voltage of each of the plurality of unit cells E1-Em or the plurality of cell blocks Eb1-Ebm, or may be only the maximum cell voltage and the minimum cell voltage.Furthermore, the temperature measurement data temporarily stored in working memory 253 as measurement data of temperature to be transmitted may be the temperatures of each of the plurality of observation points in battery pack 20, or may be only the maximum temperature and the minimum temperature.

[0023] The change amount detection unit 254 calculates the amount of change between two adjacent points in the first transmission period for each series of measurement data. The first transmission period is the normal transmission period from the battery pack 20, and as described above, is set to 10 seconds in this embodiment. The change amount detection unit 254 can calculate the amount of change between two adjacent points in the first transmission period simply as the difference (differential) between the two points.

[0024] Furthermore, the change amount detection unit 254 may calculate the amount of change between two adjacent points in the first transmission cycle by also referring to at least one value between the two points. The measurement data for each point between the two points may be an instantaneous value acquired in the sampling cycle, or may be a smoothed value smoothed in the storage cycle. For example, the change amount detection unit 254 may perform linear regression by the least squares method using values ​​from three or more points, including the two adjacent points in the first transmission cycle and at least one point between the two points, and set the slope of the regression line as the amount of change between the two points.

[0025] The change amount detection unit 254 determines whether the current change amount between the previous value and the current value in the first transmission cycle of the measurement data has changed by more than a set ratio from the previous change amount between the value before last and the previous value. The designer can determine the value of the set ratio based on the results of experiments or simulations and the designer's knowledge.

[0026] The set ratios are specified as absolute values. The set ratio for the voltage measurement data, the set ratio for the current measurement data, and the set ratio for the temperature measurement data may be set to different values. For example, among the voltage, current, and temperature, the current changes most rapidly, the voltage changes next rapidly, and the temperature changes most slowly. For example, each set ratio may be set to satisfy the relationship (set ratio for the current measurement data > set ratio for the voltage measurement data > set ratio for the temperature measurement data).

[0027] In the voltage measurement data, the set ratio in the overcharge region (e.g., 4.3 V or higher) and the overdischarge region (e.g., 2.5 V or lower) may be set lower than the set ratio in the normal region. Note that when the voltage measurement data is a value in the overcharge region or the overdischarge region, it may be unconditionally handled in the same way as when a change equal to or greater than the set ratio is detected.

[0028] In the current measurement data, the set ratio in the overcurrent region may be set lower than the set ratio in the normal region. The boundary between the overcharge region and the normal region is set depending on the application. Note that when the current measurement data is a value in the overcurrent region, it may be unconditionally treated in the same way as when a change equal to or greater than the set ratio is detected.

[0029] In the temperature measurement data, the set ratio in the high temperature range (for example, 50 degrees or higher) and the low temperature range (for example, -20 degrees or lower) may be set lower than the set ratio in the normal range. Note that when the temperature measurement data is a value in the high temperature range or the low temperature range, it may be unconditionally handled in the same way as when a change equal to or greater than the set ratio is detected.

[0030] If no change equal to or greater than the set ratio is detected, the transmission cycle setting unit 255 sets the measurement data to be output from the working memory 253 at a first transmission cycle. If a change equal to or greater than the set ratio is detected, the transmission cycle setting unit 255 sets the measurement data to be output from the working memory 253 at a second transmission cycle that is shorter than the first transmission cycle. The second transmission cycle is a transmission cycle when data is transmitted finely from the battery pack 20, and can be set to the storage cycle, for example. In this case, in this embodiment, the second transmission cycle is 1 s, which means that measurement data is transmitted at 10 times the density of the first transmission cycle of 10 s.

[0031] The second transmission period may be variable. For example, the transmission period setting unit 255 may set the second transmission period more precisely as the rate of change in the current change amount in the first transmission period relative to the rate of change in the previous change amount in the first transmission period increases. For example, the transmission period setting unit 255 may set the second transmission period to be actually used as a value obtained by multiplying the default second transmission period by the inverse of the rate of change. For example, if the rate of change is 100%, the transmission period setting unit 255 sets the second transmission period to be actually used as 0.01 times the default second transmission period (1 / 100 seconds in this embodiment). For example, the transmission period setting unit 255 may set the second transmission period to be actually used as a value obtained by multiplying the inverse of the rate of change by the default second transmission period and a predetermined coefficient α.

[0032] The second transmission period may be fixed to the same value as the sampling period of the measurement data. For example, the second transmission period (=sampling period) may be fixed to 100 ms. In this case, the smoothing processing unit 252 stores the measurement data acquired at the sampling period in the working memory 253 as is.

[0033] The data transmission unit 256 transmits the measurement data output from the working memory 253 at the transmission period set by the transmission period setting unit 255 to the communication unit 26, thereby transmitting the data to the external battery analysis system 10 via the network 5.

[0034] When reading out measurement data from the working memory 253 in a first transmission cycle, the data transmission unit 256 may calculate a moving average value or a moving median value of a plurality of measurement data included in a first predetermined interval stored in the working memory 253, and use the calculated measurement data as the measurement data for transmission. When reading out measurement data in a second transmission cycle, the data transmission unit 256 may also calculate a moving average value or a moving median value of a plurality of measurement data included in a second predetermined interval that is shorter than the first predetermined interval, and use the calculated measurement data as the measurement data for transmission.

[0035] The communication unit 26 of the ECU transmits battery data including the measurement data received from the BMS 25 to the battery analysis system 10 via the network 5. In addition to the measurement data of voltage, current, and temperature, the battery data may also include the SOC (State Of Charge) of the battery pack system 21, vehicle speed data of the electric vehicle 1, and the like.

[0036] Returning to Fig. 1, the battery analysis 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 via a wired or wireless connection.

[0037] The control unit 11 includes a data receiving unit 111, a data interpolation unit 112, and a battery state analysis unit 113. The functions of the control unit 11 can be realized by a combination of hardware and software resources, or by hardware resources alone. Examples of hardware resources that can be used include a CPU, ROM, RAM, GPU, ASIC, FPGA, and other LSIs. Examples of software resources that can be used include programs such as an operating system and applications.

[0038] The CPU executes a program stored in the memory of the control unit 11, and the computer functions as the control unit 11. In this example, the program is pre-recorded in the memory of the control unit 11, but it may also be provided via a telecommunications line such as the Internet, or by being recorded on a (non-transitory) recording medium such as a memory card.

[0039] The storage unit 12 includes a non-volatile recording medium such as an HDD or SSD, and stores various types of data. The storage unit 12 includes a battery data holding unit 121. The data receiving unit 111 receives battery data including measurement data of the battery pack 20 mounted on the electric vehicle 1 from the electric vehicle 1. The data receiving unit 111 stores the received battery data in the battery data holding unit 121.

[0040] The battery state analysis unit 113 reads out the battery data stored in the battery data storage unit 121 at a predetermined analysis timing, and analyzes the read-out battery data to estimate the battery state. The battery analysis service provider can provide various analysis functions of the battery pack 20 (e.g., SOH (State Of Health) analysis, cell balancing proposal, voltage abnormality determination, temperature abnormality determination, initial abnormality determination, internal short circuit detection, sensor abnormality determination, etc.) to the customer user.

[0041] Prior to analyzing the battery state using the battery data read from the battery data storage unit 121, the data interpolation unit 112 interpolates the measurement data for the section received in the first transmission cycle, which is included in the read battery data, so that the data density becomes equal to the data density of the second transmission cycle. Specifically, the data interpolation unit 112 linearly interpolates between two adjacent points of the measurement data for the section received in the first transmission cycle. Note that polynomial interpolation such as spline interpolation may be used instead of linear interpolation. The timing of the data interpolation may be immediately before the battery state analysis, or may be when the battery data is received if there is sufficient capacity in the storage unit 12.

[0042] FIG. 4A is a diagram showing a specific example of a transmission cycle of measurement data according to a comparative example. FIG. 4B is a diagram showing a specific example of a restored waveform in the battery analysis system 10 corresponding to FIG. 4A. The solid line in FIG. 4A indicates a time series set of measurement data acquired at a sampling cycle. Although the measurement data is actually sampled at discrete values, it is depicted as a continuous line for convenience. The circles indicate the timing of the measurement data transmitted from the BMS 25 at a first transmission cycle. The dotted line in FIG. 4B indicates a time series set of measurement data at a sampling cycle restored by the battery analysis system 10 by linearly interpolating the measurement data received at the first transmission cycle.

[0043] Fig. 5 is a diagram showing a specific example of a transmission cycle of measurement data according to an embodiment. Fig. 6 is a diagram showing a specific example of a restored waveform in the battery analysis system 10 corresponding to Fig. 5. The solid lines shown in Fig. 5 indicate a time series set of measurement data acquired at a sampling cycle. Large circles indicate the timing of measurement data transmitted from the BMS 25 at a first transmission cycle. Small circles indicate the timing of measurement data transmitted from the BMS 25 at a second transmission cycle.

[0044] In the first transmission cycle, the third change amount Δd3 between the third and fourth values ​​from the beginning has changed from the second change amount Δd2 between the second and third values ​​from the beginning by more than a set ratio, so measurement data is transmitted in the second transmission cycle for the section between the third and fourth values ​​from the beginning. In the first transmission cycle, the fourth change amount Δd4 between the fourth and fifth values ​​from the beginning has changed from the third change amount Δd3 by more than a set ratio, so measurement data is also transmitted in the second transmission cycle for the section between the fourth and fifth values ​​from the beginning. In reality, this section does not need to be transmitted in the second transmission cycle, but it is transmitted in the second transmission cycle to simplify the algorithm on the transmitting side.

[0045] In the first transmission period, the 7thb change amount Δd7b of the sixth and seventh values ​​from the end has changed by more than the set ratio from the 8thb change amount Δd8b of the seventh and eighth values ​​from the end, so measurement data is transmitted in the second transmission period for the section between the sixth and seventh values ​​from the end.In the first transmission period, the 6thb change amount Δd6b of the fifth and sixth values ​​from the end has not changed by more than the set ratio from the 7thb change amount Δd7b, so measurement data is not transmitted in the second transmission period for the section between the fifth and sixth values ​​from the end.

[0046] The dotted lines in Fig. 6 indicate a time series set of measurement data for a sampling period that is restored by linearly interpolating the measurement data received in the first transmission period or the second transmission period by the battery analysis system 10. Comparing the restored waveform of the measurement data in Fig. 4B with the restored waveform of the measurement data in Fig. 6, it can be seen that the measurement data shown in Fig. 6 has higher reproduction accuracy.

[0047] 7 is a flowchart illustrating a first example of a measurement data transmission process performed by the BMS 25 according to the embodiment. The measurement data acquisition unit 251 acquires measurement data of voltage, current, and temperature from the voltage sensor 22, current sensor 23, and temperature sensor 24 in the battery pack 20 at intervals of 100 ms (S10).

[0048] The smoothing processing unit 252 smooths or thins out the measurement data of each series acquired at 100 ms intervals and temporarily stores the result at 1 s intervals in the working memory 253 (S11). The change amount detection unit 254 calculates the amount of change between two adjacent points in the time series at 10 ms intervals for each series of measurement data (S12).

[0049] The change amount detection unit 254 determines whether the current change amount between two adjacent points has changed by more than a set ratio compared to the previous change amount (S13). If the change is not more than the set ratio (N in S13), the transmission cycle setting unit 255 sets the transmission cycle of the measurement data to a 10-second cycle (S14). If the change is more than the set ratio (Y in S13), the transmission cycle setting unit 255 sets the transmission cycle for the section between the previous value and the current value in the 10-second cycle to a 1-second cycle (S15). The data transmission unit 256 transmits the measurement data for each series at the set transmission cycle (S17). The processes of steps S10 to S17 described above are repeatedly executed until the measurement data transmission process is completed (Y in S18) (N in S18).

[0050] 8 is a flowchart for explaining a second example of the transmission process of measurement data by the BMS 25 according to the embodiment. The flowchart of the second example of the transmission process shown in FIG. 8 is obtained by replacing the processes of steps S13 to S15 of the flowchart of the first example of the transmission process shown in FIG. 7 with the process of step S13a. Differences from the first example of the transmission process shown in FIG. 7 will be explained below.

[0051] The change amount detection unit 254 sets the transmission period according to the rate of change between the current change amount and the previous change amount between two adjacent points (S13a). At this time, the change amount detection unit 254 sets the transmission period finer as the rate of change between the current change amount and the previous change amount increases. The data transmission unit 256 transmits the measurement data of each series at the set transmission period (S17).

[0052] As described above, according to this embodiment, only the measurement data for the section where the amount of change between two points in the first transmission period is significantly changed is transmitted in the second transmission period, which is shorter than the first transmission period. This reduces the amount of data transmitted from the battery pack 20 while improving the waveform reproducibility of the measurement data in the battery analysis system 10. Since the battery analysis system 10 can reproduce the waveform of the measurement data with high accuracy, the analysis accuracy of the battery pack 20 can be improved.

[0053] Since the amount of change between two adjacent points in the first transmission period is calculated and the rate of change of the amount of change before and after is calculated, the amount of calculation can be significantly reduced compared to when the amount of change between two adjacent points in the sampling period or storage period is calculated and the rate of change of the amount of change before and after is calculated. In the above example, the amount of change in a 10-second period is monitored, so the burden of monitoring the amount of change is very small.

[0054] 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.

[0055] In the above embodiment, an example has been described in which three series of measurement data, i.e., voltage, current, and temperature, are transmitted from the battery pack 20 to the battery analysis system 10. However, the specification may be such that one or two series of measurement data, among voltage, current, and temperature, are transmitted. For example, the measurement data of voltage and current may be transmitted, and the transmission of the temperature measurement data may be omitted.

[0056] In the above embodiment, a four-wheeled electric vehicle is assumed as the electric vehicle 1. 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.

[0057] Furthermore, the device in which the battery pack 20 is mounted is not limited to the electric vehicle 1. Devices in which the battery pack 20 is mounted include electric vehicles such as electric ships, railway vehicles, and multicopters (drones), stationary power storage systems, and consumer electronic devices (notebook PCs and smartphones).

[0058] The embodiment may be specified by the following items.

[0059] [Item 1] A battery management system (25) comprising: a measurement data acquisition unit (251) that acquires at least one of measurement data of voltage, current, and temperature from sensors (22, 23, 24) in a battery pack (20) at a predetermined sampling period; a data transmission unit (256) that transmits the acquired measurement data to an external device via a network (5) at a first transmission period; and a change amount detection unit (254) that determines whether a current change amount between a previous value and a current value of the measurement data in the first transmission period has changed by a set ratio or more from a previous change amount between a value before last and the previous value, wherein the data transmission unit (256) transmits measurement data for a section between the previous value and the current value at a second transmission period that is shorter than the first transmission period when a change of the set ratio or more is detected.

[0060] This makes it possible to reduce the amount of data transmitted from the battery pack (20) while improving the waveform reproducibility of the measurement data on the receiving side.

[0061] [Item 2] The battery management system (25) according to Item 1, further comprising a transmission cycle setting unit (255) that sets the second transmission cycle more finely as a rate of change of the current amount of change in the first transmission cycle relative to the previous amount of change in the first transmission cycle increases.

[0062] This allows adaptive optimization of the amount of data transmitted from the battery pack (20).

[0063] [Item 3] The battery management system (25) according to Item 1, further comprising a transmission period setting unit (255) that sets the second transmission period to the sampling period.

[0064] This allows the receiving side to reproduce with higher accuracy the waveform of the measurement data in a section where there is a large change.

[0065] [Item 4] The battery management system (25) according to Item 1, further comprising a smoothing processing unit (252) that smoothes a plurality of pieces of measurement data acquired in time series from the sensors (22, 23, 24).

[0066] This makes it possible to reduce the influence of noise contained in the measurement data.

[0067] [Item 5] The battery management system (25) according to Item 1, wherein the change amount detection unit (254) calculates the current change amount in the first transmission cycle by also referring to at least one value included in an interval between a previous value and the current value, and calculates the previous change amount by also referring to at least one value included in an interval between a value before last and the previous value.

[0068] This allows the amount of change between two adjacent values ​​in the first transmission period to be modeled with higher accuracy.

[0069] [Item 6] The battery management system (25) according to any one of Items 1 to 5, wherein the set ratio for the voltage measurement data, the set ratio for the current measurement data, and the set ratio for the temperature measurement data are set to different values.

[0070] This allows the amount of data to be transmitted to be optimized for each measurement item.

[0071] [Item 7] A battery management method comprising the steps of: acquiring at least one of measurement data of voltage, current, and temperature from sensors (22, 23, 24) in a battery pack (20) at a predetermined sampling period; transmitting the acquired measurement data to an external device via a network (5) at a first transmission period; and determining whether a current change amount between a previous value and a current value of the measurement data in the first transmission period has changed by a set ratio or more from a previous change amount between a value before last and the previous value, wherein if a change of the set ratio or more is detected, the transmitting step transmits measurement data for a section between the previous value and the current value at a second transmission period that is shorter than the first transmission period.

[0072] This makes it possible to reduce the amount of data transmitted from the battery pack (20) while improving the waveform reproducibility of the measurement data on the receiving side.

[0073] [Item 8] A battery management program that causes a computer to execute the following steps: acquiring at least one of measurement data of voltage, current, and temperature from sensors (22, 23, 24) in a battery pack (20) at a predetermined sampling period; transmitting the acquired measurement data to an external device via a network (5) at a first transmission period; and determining whether a current change amount between a previous value and a current value in the first transmission period of the measurement data has changed by a set ratio or more compared to a previous change amount between a value before last and the previous value, wherein, when a change of the set ratio or more is detected, the transmission process transmits measurement data for a section between the previous value and the current value at a second transmission period that is shorter than the first transmission period.

[0074] This makes it possible to reduce the amount of data transmitted from the battery pack (20) while improving the waveform reproducibility of the measurement data on the receiving side.

[0075] REFERENCE SIGNS LIST 1 Electric vehicle, 5 Network, 10 Battery analysis system, 11 Control unit, 12 Memory unit, 13 Communication unit, 20 Battery pack, 21 Assembled battery system, 22 Voltage sensor, 23 Current sensor, 24 Temperature sensor, 25 BMS, 26 Communication unit, 111 Data receiving unit, 112 Data interpolation unit, 113 Battery state analysis unit, 121 Battery data storage unit, 251 Measurement data acquisition unit, 252 Smoothing processing unit, 253 Working memory, 254 Change amount detection unit, 255 Transmission cycle setting unit, 256 Data transmission unit.

Claims

1. A battery management system comprising: a measurement data acquisition unit that acquires at least one of measurement data of voltage, current, and temperature from a sensor in a battery pack at a predetermined sampling period; a data transmission unit that transmits the acquired measurement data to the outside via a network at a first transmission period; and a change amount detection unit that determines whether a current change amount between a previous value and a current value of the measurement data in the first transmission period has changed by more than a set ratio compared to a previous change amount between the value before last and the previous value, wherein when a change of more than the set ratio is detected, the data transmission unit transmits measurement data for the section between the previous value and the current value at a second transmission period that is shorter than the first transmission period.

2. The battery management system according to claim 1, further comprising a transmission period setting unit that sets the second transmission period more finely as a rate of change in the current amount of change in the first transmission period relative to the previous amount of change in the first transmission period increases.

3. The battery management system according to claim 1, further comprising a transmission period setting unit that sets the second transmission period to the sampling period.

4. The battery management system according to claim 1, further comprising a smoothing processing unit that smoothes a plurality of pieces of measurement data acquired in time series from the sensor.

5. A battery management system as described in claim 1, wherein the change amount detection unit calculates the current change amount in the first transmission period by also referring to at least one value included in the interval between the previous value and the current value, and calculates the previous change amount by also referring to at least one value included in the interval between the value before last and the previous value.

6. A battery management system according to any one of claims 1 to 5, wherein the set ratio for the voltage measurement data, the set ratio for the current measurement data, and the set ratio for the temperature measurement data are each set to a different value.

7. A battery management method comprising the steps of: acquiring at least one of measurement data of voltage, current, and temperature from a sensor in a battery pack at a predetermined sampling period; transmitting the acquired measurement data to the outside via a network at a first transmission period; and determining whether or not a current change amount between a previous value and a current value in the first transmission period of the measurement data has changed by a set ratio or more from a previous change amount between a value before last and the previous value, wherein if a change of the set ratio or more is detected, the transmitting step transmits measurement data for the section between the previous value and the current value at a second transmission period that is shorter than the first transmission period.

8. A battery management program that causes a computer to execute the following processes: acquiring at least one of measurement data of voltage, current, and temperature from a sensor in a battery pack at a predetermined sampling period; transmitting the acquired measurement data to the outside via a network at a first transmission period; and determining whether or not a current change in the measurement data between a previous value and a current value in the first transmission period has changed by a set ratio or more compared to a previous change between the value before last and the previous value, and when a change of the set ratio or more is detected, the transmission process transmits measurement data for the section between the previous value and the current value at a second transmission period that is shorter than the first transmission period.

9. A recording medium on which the battery management program according to claim 8 is recorded.

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