Prediction device, power storage device, prediction method, and prediction program

Abstract

The present invention is provided with: a first prediction unit that uses a power storage element model to predict voltage behavior of a power storage element when energized in a prescribed energization pattern; and a second prediction unit that predicts charge / discharge performance of the power storage element on the basis of the voltage behavior predicted by the first prediction unit. The first prediction unit predicts the voltage behavior for each section dividing the energization pattern by a time width, and the first prediction unit stops the prediction of the voltage behavior in a section of the energization pattern in which a current change amount is less than a threshold.

Description

Prediction device, power storage device, prediction method, and prediction program

[0001] The present invention relates to a prediction device, a power storage device, a prediction method, and a prediction program.

[0002] In order to realize automatic driving functions and safety functions in moving objects, there is a need to estimate the power supply performance of storage elements mounted on vehicles and the like.

[0003] The battery control device disclosed in Patent Document 1 calculates the chargeable and dischargeable power of the storage battery by treating the storage battery as an electrical equivalent circuit and simulating its charging and discharging behavior.

[0004] JP 2015-114135 A

[0005] When predicting the charge / discharge behavior of a storage element when energized according to a predetermined energization pattern using a storage element model such as an equivalent circuit, the energization pattern is divided into predetermined unit times, and the voltage is calculated for each predetermined time. Increasing the unit time used to divide the energization pattern reduces the number of calculations and shortens the prediction time, but this also reduces the prediction accuracy. Therefore, a technology that can achieve both a shorter prediction time and improved prediction accuracy is desired.

[0006] An object of the present disclosure is to provide a technology that can achieve both a reduction in prediction time and an improvement in prediction accuracy.

[0007] A prediction device according to one aspect of the present disclosure includes a first prediction unit that predicts the voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model, and a second prediction unit that predicts the charge / discharge performance of the storage element based on the voltage behavior predicted by the first prediction unit, wherein the first prediction unit predicts the voltage behavior for each interval that divides the current pattern by a time width, and the first prediction unit stops predicting the voltage behavior in an interval in which the change in current in the current pattern is less than a threshold value.

[0008] According to the present disclosure, it is possible to achieve both a reduction in prediction time and an improvement in prediction accuracy.

[0009] 7 is a diagram showing an example of a discharge pattern; FIG. 8 is a diagram showing an example of discharge pattern data corresponding to the discharge pattern of FIG. 1; FIG. 9 is a perspective view showing an example of the configuration of a power storage device; FIG. 10 is an exploded perspective view of a power storage device; FIG. 11 is a block diagram showing an example of the configuration of a power storage device including a prediction device; FIG. 12 is a circuit diagram showing an example of a storage element model; FIG. 13 is a diagram showing an example of a discharge pattern after adjustment; FIG. 14 is a diagram showing an example of discharge pattern data after adjustment corresponding to the discharge pattern of FIG. 7; FIG. 15 is a flowchart showing an example of a processing procedure for adjusting a current conduction pattern executed by the prediction device; and FIG. 16 is a flowchart showing an example of a processing procedure for predicting whether current conduction is possible executed by the prediction device.

[0010] (1) A prediction device according to one aspect of the present disclosure includes a first prediction unit that predicts voltage behavior of an energy storage element when current is applied according to a predetermined current application pattern using a storage element model, and a second prediction unit that predicts charge / discharge performance of the energy storage element based on the voltage behavior predicted by the first prediction unit. The first prediction unit predicts the voltage behavior for each interval that divides the current application pattern by a time width, and the first prediction unit stops predicting the voltage behavior in an interval in which a change in current in the current application pattern is less than a threshold. In other words, the first prediction unit does not predict the voltage behavior in an intermediate interval among multiple temporally consecutive intervals in which a change in current in the current application pattern is less than a threshold.

[0011] Here, the "energy storage element" may be a power storage cell or a power storage unit having a plurality of power storage cells. The "current flow pattern" may be, for example, a current pattern based on a current value and a current flow time.

[0012] To ensure the reliable operation of autonomous driving and safety functions, energy storage devices installed in vehicles are required to always be able to perform a predetermined charging or discharging capacity. For example, whenever discharge is required, the energy storage device is required to perform a predetermined discharging capacity for an electrical load connected to the energy storage device. The prediction device is required to predict whether or not current can be applied according to a predetermined current application pattern at a predetermined calculation period.

[0013] The prediction device calculates a predicted voltage value of the storage element when current is applied in a predetermined current pattern using a storage element model, and predicts whether discharge will occur based on the calculated predicted voltage value. In calculating the predicted voltage value, the current pattern is divided into time intervals each having a time width, and a predicted voltage value is calculated for each interval.

[0014] Fig. 1 is a diagram showing an example of a discharge pattern, and Fig. 2 is a diagram showing an example of discharge pattern data corresponding to the discharge pattern of Fig. 1. The vertical axis of the graph shown in Fig. 1 represents current (unit: ampere (A)), and the horizontal axis represents elapsed time (unit: seconds (s)). Figs. 1 and 2 show discharge patterns as current flow patterns. In Figs. 1 and 2, the positive side of the current represents charging power, and the negative side represents discharging power.

[0015] In the discharge pattern indicated by the black squares and solid lines in FIG. 1 , the current value at the start (0 seconds) is set to zero, and the discharge current value (absolute value of the current value) gradually increases from 0 seconds to 0.15 seconds, gradually decreases from 0.15 seconds to 0.3 seconds, remains constant from 0.3 seconds to 0.65 seconds, gradually increases from 0.65 seconds to 0.75 seconds, and gradually decreases from 0.75 seconds to the end (1 second).

[0016] The current value in the discharge pattern is recorded at each predetermined interval to obtain the discharge pattern data shown in Fig. 2. In the examples of Figs. 1 and 2, the interval is 0.05 seconds.

[0017] The storage element model predicts the voltage value after a constant current is applied for a predetermined period of time. When calculating the predicted voltage using the storage element model, the voltage value within each time period is assumed to be constant. In Figure 1, the white circles and dashed lines indicate the recognition pattern recognized during calculation based on the discharge pattern.

[0018] The discharge current value from 0 seconds to 0.05 seconds gradually increases from 0 A to 100 A in the actual discharge pattern, but is recognized as a constant 100 A during calculation. A discrepancy in the recognition of the current value results in a discrepancy between the consumed capacity in the discharge pattern and the consumed capacity during calculation. The discrepancy in consumed capacity causes a deterioration in the prediction accuracy of the predicted voltage value using the energy storage element model. If the current conduction pattern includes a section in which the current changes, the prediction accuracy of the predicted voltage value deteriorates. The deterioration in prediction accuracy due to a current conduction pattern involving current changes becomes more severe the longer the total current conduction time of the current conduction pattern, as the discrepancy in consumed capacity increases.

[0019] In order to improve the prediction accuracy of current conduction patterns that involve current changes, it is preferable to shorten the division time, but shortening the division time increases the number of calculations, which increases the calculation cost and prediction time. When there are multiple types of current conduction patterns to be predicted, prediction is required for each current conduction pattern, which further increases the load.

[0020] If the number of calculations increases, there is a risk that predictions for all time points cannot be completed in a specific calculation period within the allowable time allowed for the discharge feasibility prediction process. To complete predictions within the allowable time, it is possible to shorten the calculation period or lengthen the division time of the discharge pattern to reduce the number of calculations. Shortening the calculation period is undesirable because it increases the load on the prediction device and is also limited from a performance perspective. Lengthening the division time will result in the original current flow pattern not being properly reflected, leading to a deterioration in prediction accuracy. For example, if the division time of the discharge pattern shown in FIG. 1 is set to 0.1 seconds, the discharge pattern data will be -200 A at 0.1 seconds followed by -250 A at 0.2 seconds, and the -300 A at 0.3 seconds will not be reflected. With a division time of 0.1 seconds, the minimum predicted voltage value will be higher than with a division time of 0.05 seconds, leading to a deterioration in the prediction accuracy of discharge feasibility.

[0021] According to the prediction device described in (1) above, during a period in which the change in current in the current conduction pattern is less than a threshold, calculations for voltage prediction are not performed in the middle of the period, thereby reducing the overall number of calculations. By shortening the division time, prediction time can be shortened while improving prediction accuracy. The prediction device may predict voltage behavior across multiple consecutive periods in a single calculation process by connecting multiple consecutive periods in which the change in current is less than the threshold to create a single new period. By reducing the number of calculations only during periods in which the change in current is less than the threshold, calculations can be performed efficiently while suppressing deterioration in prediction accuracy. Based on the voltage behavior predicted in this way, charge / discharge performance can be predicted efficiently and accurately.

[0022] (2) In the prediction device described in (1) above, the current pattern may include a section in which the current is constant.

[0023] According to the prediction device described in (2) above, it is possible to improve the prediction accuracy and reduce the calculation load for a current conduction pattern including a section in which the current is constant.

[0024] (3) In the prediction device described in (1) or (2) above, the first prediction unit may adjust the current flow pattern based on the current at a switching point where the consumption capacity or the direction of increase or decrease of the current switches in a section where the amount of change in current in the current flow pattern is equal to or greater than a threshold, and predict the voltage behavior based on the adjusted current flow pattern.

[0025] According to the prediction device described in (3) above, the current value of the current conduction pattern can be adjusted taking into account the consumed capacity in the current conduction pattern. By adjusting the current conduction pattern, it is possible to eliminate the discrepancy between the consumed capacity of the current conduction pattern and the capacity recognized at the time of calculation. In addition, the current value of the current conduction pattern can be adjusted taking into account the current at the switching point where the direction of increase or decrease of the current switches. Since the maximum or minimum current value can be reflected in the adjustment of the current conduction pattern, it is possible to prevent the minimum voltage value from being predicted higher than the actual value or the maximum voltage value from being predicted lower than the actual value. This improves the prediction accuracy for current conduction patterns that include sections where the current changes.

[0026] (4) In the prediction device described in (3) above, the section in which the amount of change in current in the current pattern is equal to or greater than a threshold value may include a section in which the direction of increase / decrease of the current switches and a section in which the direction of increase / decrease of the current does not switch, and the first prediction unit may adjust the current pattern based on the current at the switching point in the section in which the direction of increase / decrease of the current switches and the consumption capacity in the section in which the direction of increase / decrease of the current does not switch.

[0027] According to the prediction device described in (4) above, in a section where the direction of increase or decrease of the current does not change, a power value according to the consumption capacity is used to eliminate discrepancies in the consumption capacity, and in a section where the direction of increase or decrease of the current changes, the actual current value is used instead of adjustments that take the consumption capacity into account, thereby making it possible to accurately predict the minimum or maximum value of the predicted voltage value.

[0028] (5) In the prediction device described in any one of (1) to (4) above, the current flow pattern may include a section in which the amount of change in current in the current flow pattern is less than a predetermined value and a section in which the amount of change in current is greater than or equal to a predetermined value.

[0029] According to the prediction device described in (5) above, it is possible to improve prediction accuracy and reduce the calculation load for a current conduction pattern that includes a period in which the current is almost constant and a period in which the current is changing, and to efficiently and accurately determine charge / discharge performance for a variety of current conduction patterns.

[0030] (6) The prediction device according to any one of (1) to (5) above may further include an output unit that outputs the charge / discharge performance of the storage element predicted by the second prediction unit to an external device.

[0031] According to the prediction device described in (6) above, the determined charge / discharge performance can be reliably notified to an external device.

[0032] (7) A power storage device according to one aspect of the present disclosure includes a power storage element and the prediction device according to any one of (1) to (6) above.

[0033] (8) A prediction method according to one aspect of the present disclosure uses a storage element model to predict the voltage behavior of a storage element when current is applied in a predetermined current pattern, predicts the charge / discharge performance of the storage element based on the predicted voltage behavior, predicts the voltage behavior for each interval that divides the current pattern in the time axis direction, and stops predicting the voltage behavior in an interval in which the amount of change in current in the current pattern is less than a threshold value.

[0034] (9) A prediction program according to one aspect of the present disclosure causes a computer to execute a process of predicting the voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model, predicting the charge / discharge performance of the storage element based on the predicted voltage behavior, predicting the voltage behavior for each interval that divides the current pattern in the time axis direction, and stopping the prediction of the voltage behavior in an interval in which the amount of change in current in the current pattern is less than a threshold value.

[0035] (10) A prediction device according to one aspect of the present disclosure includes a first prediction unit that predicts the voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model, and a prediction unit that predicts the charge / discharge performance of the storage element based on the voltage behavior predicted by the first prediction unit, wherein the first prediction unit divides the current pattern into a plurality of periods and predicts the voltage behavior for each period, and the duration of a period in which the amount of change in current in the current pattern is less than a threshold value is longer than the duration of a period in which the amount of change in current in the current pattern is greater than or equal to a predetermined value.

[0036] According to the prediction device described in (10) above, the length of the time span for executing the voltage behavior prediction calculation can be varied depending on whether or not there is a change in current in the current conduction pattern, thereby improving calculation efficiency while suppressing deterioration in prediction accuracy.

[0037] The present disclosure will be specifically described with reference to the drawings showing embodiments thereof.

[0038] (First embodiment) Fig. 3 is a perspective view showing a configuration example of the energy storage device 1, and Fig. 4 is an exploded perspective view of the energy storage device 1. Below, the configuration example of the energy storage device 1 will be described with reference to the "front-rear," "left-right," and "up-down" directions shown in the drawings.

[0039] The power storage device 1 is a battery that is suitable for installation in, for example, an engine vehicle, an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc. The power storage device 1 is, for example, a 12 volt (V) battery or a 48 V battery.

[0040] The energy storage device 1 includes a plurality of energy storage cells 2, a prediction device 3, and a busbar unit 4. The energy storage device 1 is an example of an energy storage element. The energy storage cells 2, the prediction device 3, and the busbar unit 4 are housed inside a housing case 10. The energy storage cells 2 are, for example, battery cells formed of lithium-ion secondary batteries.

[0041] In an embodiment, the storage element is a storage unit having a plurality of storage cells 2. Alternatively, the storage element may be a single storage cell 2.

[0042] The prediction device 3 is, for example, a battery management system (BMS). The prediction device 3 predicts whether the power storage device 1 satisfies the charge capacity or discharge capacity related to a predetermined current pattern, that is, predicts the charge / discharge performance of the power storage device 1.

[0043] In the embodiment, the prediction device 3 is mounted inside the power storage device 1. Alternatively, the prediction device 3 may be installed remotely from the power storage device 1. The prediction device 3 may be a computer such as a server device, a terminal device, or a vehicle ECU connected to the outside of the power storage device 1. In this case, measurement data measured regarding the power storage device 1 may be transmitted to the server device or the like via communication.

[0044] The storage case 10 is made of synthetic resin. The storage case 10 includes a case body 11 with an open top and a cover 12 that covers the opening of the case body 11. The case body 11 and the cover 12 are fixed in a liquid-tight manner using fasteners such as screws, adhesive, welding, or the like, with the energy storage cells 2, the prediction device 3, and the busbar unit 4 housed inside. A pair of external terminals 13A and 13B with opposite polarities are provided on one side of the storage case 10.

[0045] The storage cell 2 includes a hollow rectangular parallelepiped case 21. A positive terminal 22 and a negative terminal 23 of the storage cell 2 are provided on the upper surface of the case 21. The case 21 accommodates an electrode assembly, an electrolyte, and the like (not shown).

[0046] The electrode assembly is constructed by stacking a sheet-shaped positive electrode and a sheet-shaped negative electrode with two sheet-shaped separators in between and winding them (vertical or horizontal). The separators are formed of a porous resin film. Examples of the porous resin film include a porous resin film made of a resin such as polyethylene (PE) or polypropylene (PP).

[0047] The positive electrode is an electrode plate in which a positive electrode active material layer is formed on the surface of a long strip-shaped positive electrode substrate made of, for example, aluminum or an aluminum alloy. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material used in the positive electrode active material layer can be a material capable of absorbing and releasing lithium ions. An example of the positive electrode active material is LiFePO4. The positive electrode active material layer may further contain a conductive additive, a binder, etc.

[0048] The negative electrode is an electrode plate in which a negative electrode active material layer is formed on the surface of a long strip-shaped negative electrode substrate made of, for example, copper or a copper alloy. The negative electrode active material layer contains a negative electrode active material. The negative electrode active material can be a material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include graphite, hard carbon, and soft carbon. The negative electrode active material layer may further contain a binder, a thickener, and the like.

[0049] The electrolyte can be the same as that used in conventional lithium-ion secondary batteries. For example, an electrolyte containing a supporting salt in an organic solvent can be used. Examples of suitable organic solvents include aprotic solvents such as carbonates, esters, and ethers. Examples of suitable supporting salts include lithium salts such as LiPF6, LiBF4, and LiClO4. The electrolyte may also contain various additives, such as a gas generating agent, a film-forming agent, a dispersant, and a thickener.

[0050] In the embodiment, the power storage cell 2 is a battery cell based on a lithium ion secondary battery. Alternatively, the power storage cell 2 may be a battery cell based on an all-solid-state battery, a lead battery, a redox flow battery, a zinc-air battery, an alkaline manganese battery, a lithium-sulfur battery, a sodium-sulfur battery, a silver-zinc oxide battery, a nickel-metal hydride battery, a molten salt thermal battery, or the like, or may be a capacitor.

[0051] In the embodiment, the energy storage cell 2 is a rectangular battery cell with a wound electrode assembly. Alternatively, the energy storage cell 2 may be a cylindrical battery cell, a laminated (pouch) battery cell, or a battery cell with a stacked electrode assembly.

[0052] In the embodiment, the number of storage cells 2 housed in the case body 11 is four. Alternatively, the number of storage cells 2 housed in the case body 11 may be one or more and less than four, or may be more than four. In the following description, the storage cells 2 will also be referred to as a first storage cell 2A, a second storage cell 2B, a third storage cell 2C, and a fourth storage cell 2D, in that order from the front side of the case body 11.

[0053] As shown in FIG. 4, each storage cell 2 is housed in the case body 11 such that the positive terminals 22 and negative terminals 23 of adjacent storage cells 2 face in opposite directions.

[0054] The prediction device 3 is disposed on the terminal surface of the energy storage cell 2 via a busbar unit 4. The busbar unit 4 includes a plurality of busbars 41 and a resin busbar frame 42 that holds these busbars 41. Each busbar 41 is connected to the underside of the prediction device 3 by a fastener 43 such as a screw. The energy storage cell 2 and the prediction device 3 are connected via the busbar 41.

[0055] The bus bar 41 constitutes a charge / discharge path for the energy storage cells 2. The bus bar 41 is made of metal, and is formed of a material with excellent electrical conductivity and high thermal conductivity, such as aluminum, an aluminum alloy, copper, a copper alloy, or stainless steel. The bus bar 41 electrically connects the positive terminal 22 of one of the energy storage cells 2 to the negative terminal 23 of the other of the adjacent energy storage cells 2. The bus bar 41 also connects the negative terminal 23 of the first energy storage cell 2A to one external terminal 13A, and also connects the positive terminal 22 of the fourth energy storage cell 2D to the other external terminal 13B.

[0056] 3 and 4, a configuration has been described in which four storage cells 2 are connected in series by the bus bar 41. Alternatively, some or all of the storage cells 2 may be connected in parallel.

[0057] The prediction device 3 includes a flat circuit board 61. A shutoff circuit 62, a temperature sensor 63, a current sensor 64, and a voltage sensor 65 (see FIG. 5 ) are also mounted on the upper surface of the circuit board 61. The prediction device 3 may be configured as a circuit board unit in which the shutoff circuit 62, the temperature sensor 63, the current sensor 64, and the voltage sensor 65 are mounted on the circuit board 61.

[0058] The interrupting circuit 62 is a circuit for connecting or disconnecting a conductive path between the bus bar 41 connected to the positive terminal 22 of the fourth storage cell 2D and the bus bar 66 connected to the external terminal 13B. The interrupting circuit 62 is configured by a semiconductor switch such as a metal oxide semiconductor field effect transistor (MOSFET). By switching the interrupting circuit 62 from an on state to an off state, it is possible to block current from flowing out from the storage cell 2 to the outside and current from flowing in from the outside to the storage cell 2. Alternatively, the interrupting circuit 62 may be configured by a relay switch.

[0059] The temperature sensor 63 is, for example, a thermistor, a thermocouple, or the like. The temperature sensor 63 measures the temperature related to the energy storage device 1. In FIG. 4 , the temperature sensor 63 is disposed at a position sufficiently separated from the energized heating elements (e.g., the interrupter circuit 62, the bus bars 41 and 66, the fasteners 43, etc.) on the circuit board 61. The temperature data measured by the temperature sensor 63 represents the ambient temperature of the energy storage device 1 (the ambient temperature of the energy storage cells 2). The energy storage element may further include a temperature sensor 63 disposed near the energized heating elements on the circuit board 61 and measuring the temperature of the energized heating elements on the circuit board 61. In this case, the temperature of the energy storage device 1 may be determined based on the ambient temperature of the energy storage device 1 and the temperature of the energized heating elements on the circuit board 61.

[0060] 5 is a block diagram showing an example of the configuration of the power storage device 1 including the prediction device 3. The power storage device 1 is connected to a vehicle ECU (Electronic Control Unit) 71, an electrical load 72 such as electrical equipment, and an alternator (not shown) via external terminals 13A and 13B.

[0061] If the vehicle is an engine vehicle, while the engine is running, if the amount of power generated by the alternator is greater than the amount of power consumed by the electrical load 72, the electrical storage device 1 is charged by the alternator. If the amount of power generated by the alternator is less than the amount of power consumed by the electrical load 72, the electrical storage device 1 discharges to make up for the shortfall. When the vehicle is parked, the alternator stops generating power, so the electrical storage device 1 is not charged and only discharges to the vehicle ECU 71 and the electrical load 72.

[0062] When the vehicle can start traveling using a high-voltage system (driving power storage device) instead of an internal combustion engine, the power storage device 1 supplies power to start the high-voltage system. While the vehicle is parked, the power storage device 1 discharges power to the vehicle ECU 71 and the electrical load 72, and can also be charged by the high-voltage system.

[0063] The vehicle ECU 71 is a vehicle control unit that controls the vehicle. The vehicle ECU 71 controls the electric load 72. The vehicle ECU 71 controls the charge or discharge amount of the power storage device 1 by controlling the electric load 72 based on the prediction result of whether charging or discharging is possible received from the prediction device 3. The vehicle ECU 71 is an example of a higher-level device.

[0064] The prediction device 3 is a computer and includes a control unit 31, a storage unit 32, an input / output unit 33, and a communication unit 34. In this embodiment, the prediction device 3 is realized by a circuit board, but alternatively, the prediction device 3 may be configured to perform distributed processing using multiple computers, may be realized by multiple virtual machines provided in a single server, or may be realized using a cloud server.

[0065] The control unit 31 is an arithmetic circuit including a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The CPU or GPU included in the control unit 31 executes various computer programs stored in the ROM or the storage unit 32, and controls the operation of each of the above-mentioned hardware components. The control unit 31 may also include functions such as a timer that measures the elapsed time from when an instruction to start measurement is given until when an instruction to end measurement is given, a counter that counts numbers, and a clock that outputs date and time information.

[0066] The storage unit 32 includes a non-volatile storage device such as a flash memory, a hard disk drive, etc. The storage unit 32 stores various computer programs and data referenced by the control unit 31. The storage unit 32 may be an external storage device connected to the prediction device 3.

[0067] The storage unit 32 of this embodiment stores a prediction program 321 for causing a computer to execute processing related to predicting whether charging or discharging is possible, and prediction data 322 as data necessary for executing the prediction program 321. The prediction data 322 includes a storage element model used in the simulation. The storage element model is described by configuration information indicating the circuit configuration and values ​​of each element constituting the storage element model. The storage unit 32 stores the configuration information indicating the circuit configuration of the storage element model and values ​​of each element constituting the storage element model.

[0068] A computer program (computer program product) including the prediction program 321 may be provided by a non-transitory recording medium 3A on which the computer program is readably recorded. The recording medium 3A is, for example, a portable memory such as a magnetic disk, an optical disk, or a semiconductor memory. The control unit 31 reads the desired computer program from the recording medium 3A using a reading device (not shown) and stores the read computer program in the memory unit 32. Alternatively, the computer program may be provided via communication. The prediction program 321 may be a single computer program or may be composed of multiple computer programs, and may be executed on a single computer or on multiple computers interconnected by a communication network.

[0069] The input / output unit 33 includes an input / output interface for connecting to an external device, and is connected to a cutoff circuit 62, a temperature sensor 63, a current sensor 64, a voltage sensor 65, and the like.

[0070] The control unit 31 switches the interruption circuit 62 between an on state and an off state by outputting a control signal to the interruption circuit 62 via the input / output unit 33. The control unit 31 also acquires, via the input / output unit 33, temperature data measured by the temperature sensor 63, current data measured by the current sensor 64, and voltage data measured by the voltage sensor 65 as needed.

[0071] The current sensor 64 is, for example, a shunt resistor, and is connected in series to the storage cell 2. The current sensor 64 measures the current flowing through the storage cell 2 in a time series manner based on the voltage across the storage cell 2. Discharging and charging can be determined from the polarity (positive or negative) of the voltage across the cells. Alternatively, the current sensor 64 may be a magnetic sensor.

[0072] The voltage sensor 65 is connected in parallel to each storage cell 2. The voltage sensor 65 is connected to both ends of each storage cell 2, and measures the terminal voltage of each storage cell 2 in time series. The control unit 31 acquires data on the voltage of each storage cell 2 measured by the voltage sensor 65 and the total voltage of the storage device 1 via the input / output unit 33.

[0073] A display device such as a liquid crystal display device may be connected to the input / output unit 33. The control unit 31 may output the estimation result of the usable SOC range via the input / output unit 33 and display it on the display device.

[0074] The communication unit 34 includes a communication interface that realizes communication with the vehicle ECU 71 or other external devices. The control unit 31 transmits and receives various data, including the prediction result of whether charging or discharging is possible, to and from the vehicle ECU 71 or other external devices via the communication unit 34.

[0075] 6 is a circuit diagram showing an example of a storage element model. The storage element model is used to predict the voltage behavior of the storage device 1.

[0076] The energy storage element model shown in Fig. 6 is an equivalent circuit model that combines a voltage source for the energy storage cell 2 and circuit elements such as a resistor and a capacitor to simulate the charge and discharge behavior of the energy storage cell 2. The equivalent circuit model includes, for example, a constant voltage source, a DC resistor, and an RC parallel circuit connected in series between the positive and negative terminals. Fig. 6 shows an equivalent circuit model in which two RC parallel circuits, a first RC parallel circuit and a second RC parallel circuit, are connected in series, but the number of RC parallel circuits is not limited to two.

[0077] The constant voltage source is a voltage source that outputs a DC voltage. The voltage output by the constant voltage source is the open circuit voltage (OCV) of the storage cell 2, and V OCV Open circuit voltage VOCV is given as a function of SOC, for example. OCV may be given as a function of the actual capacity of the storage cell 2.

[0078] The DC resistor is used to describe the DC resistance component (DC impedance) of the storage cell 2, and includes a resistance element R0. The value of the resistance element R0 is given as a value that changes depending on the current flow, voltage, SOC, temperature, etc. Once the value of the resistance element R0 is determined, it is possible to calculate the voltage generated in the DC resistor when a current I flows through the equivalent circuit model. The voltage generated in the DC resistor is called the DC resistance voltage V R0 Let's say.

[0079] The two RC parallel circuits are circuit elements for describing the transient polarization characteristics of the energy storage cell 2. The first RC parallel circuit is composed of a resistive element R1 and a capacitive element C1 connected in parallel. The second RC parallel circuit is composed of a resistive element R2 and a capacitive element C2 connected in parallel. The values ​​of the resistive elements R1, R2, and the capacitive elements C1, C2 are given as values ​​that vary depending on the current flow, SOC, temperature, etc. The resistive elements R1, R2, and the capacitive elements C1, C2 determine the impedances of the first RC parallel circuit and the second RC parallel circuit. Once the impedances of the first RC parallel circuit and the second RC parallel circuit are determined, it is possible to calculate the voltages (polarization voltages) generated in the first RC parallel circuit and the second RC parallel circuit when a current I flows through the equivalent circuit model. The polarization voltage is the sum of the polarization voltage V1 generated in the first RC parallel circuit and the polarization voltage V2 generated in the second RC parallel circuit.

[0080] In the above equivalent circuit model, the terminal voltage (predicted voltage value) V between the positive terminal and the negative terminal of the storage cell 2 at the time t seconds later cell is the current I, the open circuit voltage V OCV , polarization voltage V1, polarization voltage V2, resistance elements R0, R1, R2, and capacitance elements C1, C2, it can be expressed by the following equation (1).

[0081]

[0082] The values ​​of the resistance elements R0, R1, and R2 and the capacitance elements C1 and C2 used in the equivalent circuit model are obtained in advance based on actual measurement data or the like.

[0083] The predicted voltage value V of each storage cell 2 calculated by the above formula (1) cell The predicted voltage value of the energy storage device 1 can be calculated by calculating the sum of the above. The predicted voltage value of the energy storage device 1 may be a value that takes into account voltages caused by resistance components of conductive members in the energy storage device 1 (for example, bus bars 41, 66, interrupter circuit 62, etc.).

[0084] A method for predicting whether charging or discharging is possible using the above-described storage element model executed by the prediction device 3 will be described below. The method for predicting whether charging or discharging is possible will be described below using an example in which the current conduction pattern is a discharge pattern and whether a predetermined power can be supplied (SOF: State Of Function) is predicted.

[0085] When predicting whether charging or discharging is possible, the prediction device 3 acquires information about the discharge pattern to be predicted. The discharge pattern information is specified, for example, by a higher-level device. The discharge pattern information may include a current flow value, a current flow time, and an operating voltage range related to the discharge pattern. The current flow value and current flow time are provided, for example, in the form of discharge pattern data. The discharge pattern data may be data in which the discharge pattern is divided into time intervals corresponding to predetermined division times, and the time corresponding to each division point (the elapsed time from the start point) is associated with the current value at that time. The operating voltage range is the lower limit voltage of the storage device 1 during discharging, and the upper limit voltage of the storage device 1 during charging. As an example, the discharge patterns shown in FIGS. 5 and 6 described above are assumed to be prediction targets.

[0086] The prediction device 3 uses the above-described storage element model to determine a predicted voltage value when discharging according to a specified discharge pattern. In this embodiment, the prediction device 3 adjusts the discharge pattern acquired from the higher-level device to make it suitable for prediction processing, and predicts a predicted voltage value based on the adjusted discharge pattern. The prediction device 3 reduces the number of calculations during a fixed current period of the discharge pattern. Furthermore, the prediction device 3 adjusts the current value during a current change period of the discharge pattern.

[0087] Fig. 7 is a diagram showing an example of a discharge pattern after adjustment, and Fig. 8 is a diagram showing an example of discharge pattern data after adjustment corresponding to the discharge pattern in Fig. 7. The vertical axis of the graph shown in Fig. 7 is current (unit: A), and the horizontal axis is elapsed time (unit: seconds). In Fig. 7, black squares and solid lines represent discharge patterns before adjustment, and white circles and dashed lines represent discharge patterns after adjustment and recognition patterns at the time of calculation recognized based on the discharge patterns.

[0088] The prediction device 3 calculates the difference between temporally consecutive current values ​​based on the discharge pattern data before adjustment, thereby determining the amount of change in current in each interval. In the discharge pattern data before adjustment, current values ​​are recorded for each time period separated by a fixed interval, as shown in Fig. 6 . Based on the calculation results, the prediction device 3 classifies all intervals of the discharge pattern data into intervals where the amount of change in current is non-zero and intervals where the amount of change in current is zero. In the discharge pattern of this embodiment, the intervals from 0 to 0.15 seconds and from 0.65 to 0.75 seconds are intervals where the amount of change in current is non-zero, and the interval from 0.3 to 0.65 seconds is an interval where the amount of change in current is zero.

[0089] When the discharge pattern data includes a constant current period including multiple sections that are consecutive in time and in which the amount of change in current is zero, the prediction device 3 omits data for sections in the middle of the constant current period from the discharge pattern data. In the constant current period, multiple sections that are consecutive in time and included in the current change period are regarded as one group of sections, and prediction calculations using the storage element model are performed only once for that group of sections.

[0090] 7 and 8, the period from 0.3 seconds to 0.65 seconds is a constant current period, so data for the intermediate period from 0.35 seconds to 0.6 seconds is removed. In the prediction calculation, calculation of the intermediate period (intermediate section) is omitted, and a predicted voltage value is obtained when a constant current value is applied during the current change period over the total time obtained by adding up the division times of multiple sections.

[0091] In the above, a section in which the amount of change in the current value is zero is determined, but a section in which the amount of change in the current value is less than a threshold value may be regarded as a constant current section.

[0092] Furthermore, if the discharge pattern data includes a current change period including a section in which the amount of change in current is not zero, the prediction device 3 adjusts the current value of the discharge pattern. The prediction device 3 classifies each section included in the current change period into a section in which the direction of increase or decrease of the current does not change and a section in which the direction of increase or decrease of the current changes.

[0093] In a section where the direction of the current increase / decrease does not change, the consumption capacity of the discharge pattern in that section is calculated, and the current value of the discharge pattern is adjusted to correspond to the calculated consumption capacity. The prediction device 3 calculates an adjusted current value so that the consumption capacity when discharging at a constant current value over the division time is equal to the consumption capacity of the discharge pattern.

[0094] In the section where the direction of current increase / decrease is switched, the current value of the discharge pattern corresponding to the switching point where the direction of current increase / decrease is switched is used as the adjusted current value. In the example shown in Figures 7 and 8, 0.15 seconds and 0.75 seconds correspond to the switching points, so the current values ​​corresponding to each switching point are applied as is in the sections from 0.15 seconds to 0.2 seconds and from 0.75 seconds to 0.8 seconds. The current value is adjusted for each section included in the current change period. Through the above process, the number of data points is reduced and discharge pattern data with adjusted current values ​​is generated, as shown in Figure 8.

[0095] The prediction device 3 predicts whether discharge will occur according to the discharge pattern at a predetermined calculation period based on the adjusted discharge pattern thus obtained.

[0096] The prediction device 3 uses the storage element model to calculate a predicted voltage value of the storage device 1 when discharging according to the adjusted discharge pattern. The predicted voltage value is calculated for each section of the adjusted discharge pattern. The prediction device 3 predicts whether or not discharging is possible based on the calculated predicted voltage value. Whether or not discharging is possible is predicted by determining whether or not the predicted voltage value is equal to or greater than a predetermined lower limit voltage. If the predicted voltage value is equal to or greater than the lower limit voltage throughout the entire period related to the discharge pattern, it can be determined that discharging is possible. If the predicted voltage value is less than the lower limit voltage, it can be determined that discharging is not possible.

[0097] The above description has been given using an example in which the current conduction pattern is a discharging pattern. Similarly, when the current conduction pattern is a charging pattern, the charging pattern can be adjusted by applying the above-described method. Whether or not charging will be accepted can be predicted by determining whether or not the predicted voltage value when charging with the adjusted charging pattern is equal to or lower than a preset upper limit voltage.

[0098] 9 is a flowchart showing an example of a procedure for adjusting a current application pattern executed by the prediction device 3. The process in the flowchart below is executed by the control unit 31 in accordance with a prediction program 321 stored in the storage unit 32 of the prediction device 3.

[0099] The control unit 31 of the prediction device 3 acquires current conduction pattern data (step S11). The current conduction pattern data is transmitted from, for example, a higher-level device (for example, the vehicle ECU 71).

[0100] The control unit 31 calculates the amount of current change for each section based on the acquired current pattern data, and classifies all sections of the current pattern data into sections where the amount of current change is not zero and sections where the amount of current change is zero (step S12).

[0101] The control unit 31 determines whether the current conduction pattern data includes a constant current period based on the classification result (step S13). If the control unit 31 determines that the current conduction pattern data does not include a constant current period (S13: NO), the control unit 31 proceeds to step S15.

[0102] When it is determined that the current conduction pattern data includes a constant current period (S13: YES), the control unit 31 omits data for a section midway in the constant current period from the current conduction pattern data (step S14).

[0103] The control unit 31 determines whether the current conduction pattern data includes a current change period based on the classification result (step S15). If it is determined that the current conduction pattern data does not include a current change period (S15: NO), the control unit 31 ends the process.

[0104] If it is determined that the current conduction pattern data includes a current change period (S15: YES), the control unit 31 determines whether the section included in the current change period is a section where the direction of increase or decrease of the current switches (step S16).

[0105] If it is determined that the section is not one in which the direction of increase or decrease of the current changes, i.e., the section is one in which the direction of increase or decrease of the current changes not (S16: NO), the control unit 31 calculates an adjustment current value for adjusting the discharge pattern data based on the consumption capacity in the section (step S17). The control unit 31 calculates the consumption capacity of the discharge pattern and obtains the adjustment current value so that the calculated consumption capacity is equal to the consumption capacity when discharging at the adjustment current value over the division time.

[0106] If it is determined that the current change direction is switching (S16: YES), the control unit 31 determines an adjustment current value based on the current value of the current conduction pattern corresponding to the switching point of the current change direction (step S18). The control unit 31 uses the current value at the switching point as the adjustment current value. The control unit 31 executes the processes of steps S16 to S18 for each section included in the current change period. The control unit 31 stores the discharge pattern defined by the number of data points after omission and the adjustment current value in the storage unit 32 as the adjusted current conduction pattern, and ends the series of processes.

[0107] 10 is a flowchart showing an example of a procedure for predicting whether or not power can be applied, which is executed by the prediction device 3. The control unit 31 of the prediction device 3 repeatedly executes the following process at a predetermined calculation period, for example.

[0108] The control unit 31 of the prediction device 3 acquires measurement data including the temperature, current, and voltage of the power storage device 1 (step S21).

[0109] The control unit 31, functioning as a first prediction unit, predicts a predicted voltage value of the energy storage device 1 when current is applied according to the adjusted current application pattern based on the acquired measurement data (step S22). The predicted voltage value is predicted for each section using a storage element model. The control unit 31 omits calculations for intermediate sections by collectively calculating predicted voltage values ​​for multiple sections during a constant current period in accordance with the adjusted current application pattern data. During a current change period, the control unit 31 predicts a predicted voltage value using the adjusted current value.

[0110] The control unit 31, functioning as a second prediction unit, predicts whether or not current can be passed according to the current passing pattern based on the predicted voltage value (step S23). The possibility of current passing is predicted by determining whether or not the predicted voltage value is equal to or greater than a preset lower limit voltage or equal to or less than an upper limit voltage. If the predicted voltage value is equal to or greater than the lower limit voltage or equal to or less than the upper limit voltage, it is predicted that current can be passed. If the predicted voltage value is not equal to or greater than the lower limit voltage or equal to or less than the upper limit voltage, it is predicted that current cannot be passed.

[0111] The control unit 31, using its function as an output unit, outputs information based on the prediction result of whether or not to energize to an external device (for example, the vehicle ECU 71) (step S24), and ends the series of processes.

[0112] The prediction device, the prediction method, and the prediction program can be applied to applications other than vehicles, and may be applied to flying bodies such as aircraft, flying vehicles, and HAPS (High Altitude Platform Stations), as well as to ships and submarines. The power storage device 1 may be a high-voltage battery.

[0113] According to this embodiment, by adjusting the discharge pattern, it is possible to improve the prediction accuracy of the predicted voltage value and the charge / discharge performance while shortening the prediction time.

[0114] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents thereto. The sequences shown in each embodiment are not limited, and within the scope of no contradiction, each processing step may be executed in a different order, or multiple processes may be executed in parallel. The entity that performs each process is not limited, and within the scope of no contradiction, the process of each device may be executed by another device.

[0115] The matters described in each embodiment can be combined with each other. Furthermore, the independent claims and dependent claims described in the claims can be combined with each other in any and all combinations, regardless of the reference format. Furthermore, the claims use a format in which a claim references two or more other claims (multiple claim format), but this is not limited to this. A multiple claim (multi-multi claim) that references at least one other multiple claim may also be used.

[0116] REFERENCE SIGNS LIST 1 Energy storage device (energy storage element) 2 Energy storage cell 3 Prediction device 31 Control unit 32 Storage unit 33 Input / output unit 34 Communication unit 321 Prediction program 322 Prediction data 3A Recording medium

Claims

1. A prediction device comprising: a first prediction unit that predicts voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model; and a second prediction unit that predicts charge / discharge performance of the storage element based on the voltage behavior predicted by the first prediction unit, wherein the first prediction unit predicts the voltage behavior for each interval that divides the current pattern by a time width, and the first prediction unit stops predicting the voltage behavior in an interval where a change in current in the current pattern is less than a threshold value.

2. The prediction device according to claim 1, wherein the current pattern includes a section in which the current is constant.

3. A prediction device as described in claim 1 or claim 2, wherein the first prediction unit adjusts the current flow pattern based on a current at a switching point where the consumption capacity or the direction of increase / decrease of the current switches in a section where the amount of change in current in the current flow pattern is equal to or greater than a threshold value, and predicts the voltage behavior based on the adjusted current flow pattern.

4. The prediction device described in claim 3, wherein the section in which the amount of change in current in the current pattern is equal to or greater than a threshold includes a section in which the direction of increase / decrease of current switches and a section in which the direction of increase / decrease of current does not switch, and the first prediction unit adjusts the current pattern based on the current at the switching point in the section in which the direction of increase / decrease of current switches and the consumption capacity in the section in which the direction of increase / decrease of current does not switch.

5. A prediction device according to claim 1 or claim 2, wherein the current conduction pattern includes a section in which a change in current in the current conduction pattern is less than a predetermined value, and a section in which a change in current is equal to or greater than a predetermined value.

6. The prediction device according to claim 1 or 2, further comprising an output unit that outputs the charge / discharge performance of the storage element predicted by the second prediction unit to an external device.

7. A power storage device comprising a power storage element and the prediction device according to claim 1 or 2.

8. A prediction method comprising: predicting voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model; predicting charge / discharge performance of the storage element based on the predicted voltage behavior; predicting the voltage behavior for each interval dividing the current pattern in the time axis direction; and stopping prediction of the voltage behavior in an interval where a change in current in the current pattern is less than a threshold value.

9. A prediction program that causes a computer to execute processes of predicting the voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model, predicting the charge / discharge performance of the storage element based on the predicted voltage behavior, predicting the voltage behavior for each interval that divides the current pattern in the time axis direction, and stopping prediction of the voltage behavior in an interval where the amount of change in current in the current pattern is less than a threshold value.

10. A prediction device comprising: a first prediction unit that predicts the voltage behavior of a storage element when current is applied in a predetermined current pattern using a storage element model; and a prediction unit that predicts the charge / discharge performance of the storage element based on the voltage behavior predicted by the first prediction unit, wherein the first prediction unit divides the current pattern into a plurality of periods and predicts the voltage behavior for each period, and a duration of a period during which a change in current in the current pattern is less than a threshold value is longer than a duration of a period during which a change in current in the current pattern is equal to or greater than a predetermined value.

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