Estimation method, estimation program, estimation device, and power storage device

Abstract

The estimation method uses a power storage element model that simulates the behavior of a power storage element to estimate an estimated voltage value of the power storage element when energization is performed in an assumed energization pattern, and corrects the estimated voltage value on the basis of a correction value obtained on the basis of an error in an estimated state value in the power storage element.

Description

Technical Field

[0001] The present invention relates to an estimation method, an estimation program, an estimation device, and an electric storage device. Background Art

[0002] In order to realize autonomous driving functions and safety functions in mobile objects, there is a demand for estimating the power supply performance of power storage devices mounted on vehicles and the like.

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

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-114135 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] Estimating the power supply performance of a storage element using a storage element model such as an equivalent circuit requires a state value representing the state of the storage element. Since state values ​​are often not directly measurable, an estimated state value derived from the state of the storage element is typically used. However, considering the error in the estimated state value when estimating power supply performance using such estimated state values ​​has not been fully studied. Increasing the error in the estimated state value also increases the error in the estimated power supply performance, reducing the accuracy of the power supply performance estimate.

[0009] An object of the present disclosure is to provide a technology for estimating the power supply performance of an energy storage element with high accuracy.

[0010] Means for solving problems

[0011] An estimation method according to one embodiment of the present disclosure uses an electric storage element model that simulates the behavior of the electric storage element to estimate a voltage value of the electric storage element when energized according to a predicted energization pattern. The estimated voltage value is corrected using a correction value calculated based on an error in the estimated state value of the electric storage element.

[0012] Effects of the Invention

[0013] According to the present disclosure, the power supply performance of the power storage element can be estimated with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1It is a perspective view showing a configuration example of a power storage device.

[0015] Figure 2 This is an exploded perspective view of the power storage device.

[0016] Figure 3 This is a block diagram showing a configuration example of a power storage device including an estimation device.

[0017] Figure 4 This is a diagram showing an example of a hypothetical energization pattern.

[0018] Figure 5 This is a diagram explaining a method of estimating whether or not energization can be performed based on an assumed energization pattern.

[0019] Figure 6 This is a circuit diagram showing an example of a storage element model.

[0020] Figure 7 This is a conceptual diagram showing an example of a data table of circuit parameters.

[0021] Figure 8 It is a diagram for explaining a method of estimating an SOC error.

[0022] Figure 9 This is a diagram explaining a method for estimating a temperature error caused by energization.

[0023] Figure 10 This is a diagram explaining a method for estimating a temperature error caused by a change in ambient temperature.

[0024] Figure 11 This is a flowchart showing an example of a processing procedure executed by the estimation device.

[0025] Figure 12 This is a flowchart showing an example of a processing procedure executed by the estimation device. DETAILED DESCRIPTION

[0026] (1) An estimation method according to one embodiment of the present disclosure uses a storage element model that simulates the behavior of a storage element to estimate an estimated voltage value of the storage element when energized according to an assumed energization pattern, and corrects the estimated voltage value based on a correction value obtained based on an error in an estimated state value of the storage element.

[0027] Here, the “electricity storage element” may be an electricity storage cell or an electricity storage unit (electricity storage device) including a plurality of electricity storage cells.

[0028] The assumed energization pattern may be, for example, a current pattern based on the energization time and the operating voltage range of the power storage element.

[0029] According to the estimation method described in (1) above, the estimated voltage value is corrected using a correction value efficiently and appropriately obtained based on an error in the estimated state value, thereby enabling the power supply performance (SOF: State of Function) of the storage element to be estimated with high accuracy.

[0030] The estimated voltage value (in volts (V)) of the energy storage element when energized using an assumed energization pattern is calculated using the estimated state value of the energy storage element and an energy storage element model. Estimated state values ​​are values ​​that cannot be directly measured, including, for example, the state of charge (SOC), internal resistance, and internal temperature of the energy storage element. The estimated state value may deviate from (incur an error) the actual state value of the energy storage element. By associating the potential error between the estimated state value and the actual state value (the difference between the estimated state value and the actual state value), such as the measured temperature value, with input elements to the energy storage element model, such as pre-defined values, a correction value (V) for the estimated state value can be efficiently and accurately calculated based on the set error. By correcting the estimated voltage value using the obtained correction value (V), the charge acceptance and discharge performance of the energy storage element can be appropriately estimated without overestimating or underestimating the value.

[0031] The behavior of the storage element (estimated voltage value) output by the storage element model is also an example of the estimated state value of the storage element. By presetting the error caused by the storage element model, for example, based on the duration of the power-on time of the assumed power-on pattern used in the storage element model, a correction value for the estimated state value can be efficiently and accurately determined based on the set error.

[0032] Especially when using power storage devices in mobile applications such as vehicles, it is necessary to estimate the SOF with high accuracy and minimal delay in order to ensure reliable operation of the vehicle's autonomous driving and safety functions. The above configuration can improve the reliability of SOF estimation.

[0033] (2) In the estimation method described in (1) above, a measured current value, a measured voltage value, and a measured temperature value of the storage element may be obtained, and the estimated voltage value may be estimated using the obtained measured current value, measured voltage value, and measured temperature value and the storage element model.

[0034] (3) In the estimation method described in (1) or (2) above, the correction value may be calculated to be smaller than the sum of individual correction values ​​calculated based on maximum errors of the plurality of estimated state values ​​in the storage element.

[0035] Here, the maximum error of the estimated state value may be the maximum value of the error assumed when the error is obtained by a predetermined estimation method.

[0036] When there are multiple estimated state values ​​that affect the voltage characteristics of a storage element, it is necessary to calculate a correction value by taking into account the errors in the multiple estimated state values. The inventors of the present invention, focusing on the fact that the errors in the multiple estimated state values ​​occur independently of each other, discovered that if the sum of the individual correction values ​​calculated based on the maximum errors of the multiple estimated state values ​​is used as the correction value, the correction value will be too large. According to the estimation method described in (3) above, by calculating the correction value to be smaller than the sum of the individual correction values ​​calculated based on the maximum errors of the multiple estimated state values, it is possible to prevent the charge acceptance performance or discharge performance of the storage element from being underestimated (the failure to fully utilize the performance of the storage element).

[0037] (4) In the estimation method described in any one of (1) to (3) above, the error of an estimated state value having a longer elapsed time from a predetermined timing among the plurality of estimated state values ​​may be increased.

[0038] The predetermined timing may be, for example, the timing at which the previous or most recent state value is estimated with high accuracy, the timing at which the error in the previous or most recent estimated state value is reset, or the like.

[0039] According to the estimation method described in (4) above, the length of the elapsed time, which is a factor causing an error in the estimated state value, can be reflected in the error in the estimated state value. The error in the estimated state value, which deviates from the actual state value more as the length of the elapsed time increases, can be appropriately corrected.

[0040] (5) In the estimation method described in any one of (1) to (4) above, the error of the internal temperature of the storage element in the estimated state value may be increased according to the magnitude of the change in the ambient temperature of the storage element or the magnitude of the amount of current flow.

[0041] According to the estimation method described in (5) above, the ambient temperature or the amount of current flowing into the storage element, which may be a factor in the internal temperature error in the estimated state value, can be reflected in the error in the estimated state value. The internal temperature error, which increases as the deviation from the actual state value increases with the magnitude of the change in ambient temperature or the magnitude of the current flowing into the storage element due to charging and discharging, can be appropriately corrected.

[0042] (6) In the estimation method described in any one of (1) to (5) above, the error in the output of the storage element model in the estimated state value may be increased based on at least one of the length of the power-on time, the magnitude of the current, the magnitude of the current fluctuation, and the number of times of the assumed power-on mode.

[0043] According to the estimation method described in (6) above, at least one of the length of the power-on time, the magnitude of the current, the magnitude of the current fluctuation, and the number of times of the assumed power-on pattern, which may be a factor in causing an error in the output of the storage element model in the estimated state value, can be reflected in the error in the estimated state value. This allows appropriate correction of the error in the output of the storage element model, which increases as the deviation from the actual state value increases in accordance with the length of the power-on time, the magnitude of the current, the magnitude of the current fluctuation, and the number of times of the current fluctuation.

[0044] (7) In the estimation method described in any one of (1) to (6) above, the storage element may be a storage unit having a plurality of storage cells, and a measured voltage value and a measured temperature value of each of the plurality of storage cells may be obtained. The estimated voltage value of the storage unit may be obtained based on an estimated voltage value of each of the plurality of storage cells estimated using the obtained measured voltage values ​​and measured temperature values ​​of each of the plurality of storage cells.

[0045] In a power storage unit having multiple power storage cells, the measured voltage value and measured temperature value often differ for each power storage cell. According to the estimation method described in (7) above, by obtaining the measured voltage values ​​and measured temperature values ​​of each of the multiple power storage cells, it is possible to appropriately determine the estimated voltage value of each power storage cell when energized according to the assumed energization pattern. As a result, it is possible to appropriately determine the estimated voltage value of the power storage unit.

[0046] (8) In the estimation method described in any one of (1) to (7) above, whether or not the storage element can be charged or discharged based on the assumed energization pattern may be estimated based on the estimated voltage value and the correction value.

[0047] According to the estimation method described in (8) above, it is possible to accurately estimate whether the storage element can be charged or discharged based on the voltage behavior of the storage element estimated with high accuracy through calibration. The estimation result of whether charging or discharging is possible can also be output to a higher-level device (e.g., a vehicle ECU (Electronic Control Unit), a separately installed monitoring device, a cloud server, etc.).

[0048] (9) An estimation program according to one embodiment of the present disclosure causes a computer to execute the following processing: using a storage element model that simulates the behavior of the storage element, estimating an estimated voltage value of the storage element when the storage element is energized according to an assumed energization pattern; and correcting the estimated voltage value based on a correction value obtained based on an error in the estimated state value of the storage element.

[0049] (10) An estimation device according to one embodiment of the present disclosure includes: an estimation unit that estimates an estimated voltage value of the storage element when power is supplied to the storage element according to an assumed power supply pattern, using a storage element model that simulates the behavior of the storage element; and a correction unit that corrects the estimated voltage value based on a correction value obtained based on an error in the estimated state value of the storage element.

[0050] (11) An electric storage device according to one aspect of the present disclosure includes the estimation device described in (10) above.

[0051] According to the power storage device described in (11) above, power supply performance can be easily estimated within the power storage device. By performing local processing in a short time without requiring communication with an external device, responsiveness can be improved. By using edge computing to estimate power supply performance within the power storage device, mobile objects or equipment equipped with the power storage device can use the power storage device more safely and stably.

[0052] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings showing embodiments of the present disclosure.

[0053] Figure 1 is a perspective view showing a configuration example of the power storage device 1. Figure 2 1 is an exploded perspective view of the power storage device 1. Hereinafter, a configuration example of the power storage device 1 will be described with reference to the respective directions of “front and rear,” “left and right,” and “up and down” shown in the drawing.

[0054] The power storage device 1 is a battery 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 48V battery.

[0055] The power storage device 1 includes a plurality of power storage cells 2, an estimation device 3, and a busbar unit 4. The power storage device 1 is an example of a power storage element. The power storage cells 2, the estimation device 3, and the busbar unit 4 are housed within a housing case 10. The power storage cells 2 are, for example, lithium-ion secondary battery cells.

[0056] In the embodiment, the electric storage element is an electric storage unit including a plurality of electric storage cells 2. Alternatively, the electric storage element may be a single electric storage cell 2.

[0057] Estimation device 3 is a flat-plate circuit board. For example, estimation device 3 is a battery management system (BMS). Estimation device 3 acquires measurement data including the voltages of power storage cells 2 and power storage device 1, the current flowing through power storage cells 2, and the temperature associated with power storage device 1. Based on this acquired measurement data, estimation device 3 uses a power storage element model to estimate the power supply performance of power storage device 1.

[0058] In the embodiment, estimation device 3 is mounted inside power storage device 1. Alternatively, estimation device 3 may be provided separately from power storage device 1. Estimation device 3 may also be a server device, terminal device, or computer such as a vehicle ECU connected to the outside of power storage device 1. In this case, measurement data measured by power storage device 1 can be transmitted to the server device, etc., via communication.

[0059] The housing case 10 is made of synthetic resin. It includes a housing body 11 with an open top surface and a cover 12 that covers the opening of the housing body 11. When the battery cells 2, the estimation device 3, and the busbar unit 4 are housed, the housing body 11 and the cover 12 are secured together in a fluid-tight manner using fasteners such as screws, adhesive, or welding. A pair of external terminals 13A and 13B with different polarities are provided on one side of the housing case 10.

[0060] The power storage cell 2 includes a hollow rectangular parallelepiped case 21. A positive terminal 22 and a negative terminal 23 of the power storage cell 2 are provided on the upper surface of the case 21. An electrode assembly (not shown) and an electrolyte solution are housed inside the case 21.

[0061] The electrode assembly is constructed by stacking sheets of positive and negative electrodes, interposed between two separator sheets, and then winding them (either vertically or horizontally). The separator is formed from a porous resin film. Porous resin films made of resins such as polyethylene (PE) and polypropylene (PP) can be used.

[0062] The positive electrode is an electrode plate with a positive electrode active material layer formed on the surface of a long, strip-shaped positive electrode substrate, such as aluminum or an aluminum alloy. The positive electrode active material layer contains a positive electrode active material. Materials capable of absorbing and releasing lithium ions can be used as the positive electrode active material in this layer. An example of a positive electrode active material is LiFePO4. The positive electrode active material layer may also contain a conductive additive, a binder, and the like.

[0063] The negative electrode is an electrode plate with a negative electrode active material layer formed on the surface of a long, strip-shaped negative electrode substrate, such as copper or a copper alloy. The negative electrode active material layer contains a negative electrode active material. Materials capable of absorbing and releasing lithium ions can be used as the negative electrode active material. Examples of negative electrode active materials include graphite, hard carbon, and soft carbon. The negative electrode active material layer may also contain a binder, thickener, and the like.

[0064] The electrolyte can be the same electrolyte as that used in conventional lithium-ion secondary batteries. For example, an electrolyte containing a supporting electrolyte in an organic solvent can be used. As the organic solvent, for example, aprotic solvents such as carbonates, esters, and ethers are used. As the supporting electrolyte, for example, lithium salts such as LiPF6, LiBF4, and LiClO4 are suitable. The electrolyte may also contain various additives such as a gas generator, a film forming agent, a dispersant, and a thickener.

[0065] In the embodiment, the power storage cell 2 is 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-acid 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.

[0066] In the embodiment, the power storage cell 2 is a rectangular battery cell having a wound electrode assembly. Alternatively, the power storage cell 2 may be a cylindrical battery cell, a laminated (pouch) battery cell, or a battery cell having a stacked electrode assembly.

[0067] In the embodiment, the number of power storage cells 2 housed in the case body 11 is four. Alternatively, the number of power storage cells 2 housed in the case body 11 may be one or more and less than four, or may be greater than four. In the following description, the power storage cells 2 are also referred to as the first power storage cell 2A, the second power storage cell 2B, the third power storage cell 2C, and the fourth power storage cell 2D, in order from the front of the case body 11.

[0068] like Figure 2 As shown, each power storage cell 2 is housed in the case body 11 so that the positive terminals 22 and negative terminals 23 of adjacent power storage cells 2 face opposite directions.

[0069] A busbar unit 4 is arranged on the terminal surface of the storage cell 2. The busbar unit 4 includes a plurality of busbars 41 to 45 and a resin busbar frame 46 that holds these busbars 41 to 45. The busbar frame 46 covers the upper side of the plurality of storage cells 2 and blocks the radiant heat emitted from the plurality of storage cells 2. An estimation device 3 is arranged on the upper surface of the busbar frame 46. The estimation device 3 is fixed to the busbar frame 46 via a spacer 47 in a state separated from the upper surface of the busbar frame 46. Since there is a heat insulating layer such as the busbar frame 46 and air between the estimation device 3 and the storage cell 2, the estimation device 3 is arranged to be thermally isolated from the storage cell 2. In the embodiment, the only metal components that directly connect the estimation device 3 to the storage element 2 are the busbars 41 to 45.

[0070] Busbars 41-45 form the charge and discharge paths for the power storage cells 2. Busbars 41-45 are made of metal, formed from materials with excellent electrical and thermal conductivity, such as aluminum, aluminum alloys, copper, copper alloys, and stainless steel. Busbar 41 connects the negative terminal 23 of the first power storage cell 2A to one external terminal 13A. Busbar 45 connects the positive terminal 22 of the fourth power storage cell 2D to the other external terminal 13B. Busbars 42-44 electrically connect the positive terminal 22 of one adjacent power storage cell 2 to the negative terminal 23 of the other adjacent power storage cell 2.

[0071] Busbars 41-45 are connected to the bottom surface of estimation device 3 via fasteners 48, such as screws. Power storage cells 2 are connected to estimation device 3 via busbars 41-45. Heat from estimation device 3 is transferred to power storage cells 2 via fasteners 48 and busbars 41-45. Heat generated in power storage cells 2 during charge and discharge is transferred to the top surface of estimation device 3 via busbars 41-45 and fasteners 48.

[0072] exist Figure 1 as well as Figure 2 In the above description, the four power storage cells 2 are connected in series via the bus bars 41 to 45. Alternatively, some or all of the power storage cells 2 may be connected in parallel.

[0073] The estimation device 3 includes a resin substrate 61. On the upper surface of the substrate 61, a cutoff circuit 62, a first temperature sensor 64, a second temperature sensor 65, and the like are mounted.

[0074] The cutoff circuit 62 is a circuit for connecting or cutting off the conduction path between the bus bar 45 connected to the positive terminal 22 of the fourth energy storage element 2D and the bus bar 63 connected to the external terminal 13B. The cutoff circuit 62 is composed of a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Figure 2 In the example shown, six conduction paths extending in the front-to-rear direction are formed between busbars 45 and 63. Two MOSFETs are connected in series (with their internal body diodes facing in opposite directions) in each of these six conduction paths. The two MOSFETs in each conduction path function as switches to connect and disconnect the conduction path. Furthermore, when the conduction path is disconnected, they prevent current from flowing out of the power storage cell 2 to the outside, and current from flowing into the power storage cell 2 from the outside. Alternatively, the disconnection circuit 62 may be formed by a relay switch.

[0075] The first temperature sensor 64 is a temperature sensor such as a thermistor or thermocouple, with the sensor portion insulated by a synthetic resin material or the like. The first temperature sensor 64 measures a temperature related to the internal temperature of the power storage device 1 (power storage cell 2). In this embodiment, the first temperature sensor 64 measures the ambient temperature of the power storage device 1. The ambient temperature of the power storage device 1 refers to the temperature of the space (air) within the power storage device 1. The first temperature sensor 64 can also be positioned sufficiently away from the cutoff circuit 62 and other locations to prevent it from being affected by heat from the energized heating element.

[0076] As described above, it is difficult to directly measure the internal temperature of the power storage cell 2 . In this embodiment, the ambient temperature of the power storage cell 2 measured by the first temperature sensor 64 is used instead of the internal temperature of the power storage device 1 .

[0077] The second temperature sensor 65 is a temperature sensor such as a thermistor or a thermocouple, the periphery of which is insulated by a synthetic resin material or the like. The second temperature sensor 65 measures the temperature of the heating element on the substrate 61. Figure 2 In the example, the energized heating element is a semiconductor switch provided in the cut-off circuit 62. The amount of heat generated by the energized heating element varies depending on the amount of current flowing into the power storage device 1. For example, if the power storage device 1 is charged and discharged at a high rate, the heat generated by the semiconductor switch becomes greater. The second temperature sensor 65 is arranged near the energized heating element. The so-called vicinity of the energized heating element refers to a position where the heat of the energized heating element is transferred and detected as a temperature change on the upper surface of the substrate 61. In the case where a balancer that balances the charge states (voltages) of multiple power storage cells 2 is installed on the substrate 61, the second temperature sensor 65 can also be arranged near the balancer (another example of a energized heating element).

[0078] In the embodiment, first temperature sensor 64 is located at a position separated from cutoff circuit 62 and measures the ambient temperature of power storage device 1. Alternatively, first temperature sensor 64 may be located on the surface of power storage cell 2, near a bus bar connecting power storage cell 2 and estimation device 3, or near fastener 48. In this case, first temperature sensor 64 detects a temperature that more strongly reflects the influence of heat from power storage cell 2.

[0079] The housing body 11 also houses a current sensor 66 and a voltage sensor 67 (not shown). Figure 3 The current sensor 66 is, for example, a shunt resistor, a current transformer, or a Hall effect current sensor, and measures the magnitude and direction (charging or discharging) of the current flowing through the power storage cell 2 . The voltage sensor 67 measures the terminal voltage of each power storage cell 2 .

[0080] Figure 3 This is a block diagram illustrating an example configuration of power storage device 1 including estimation device 3. Power storage device 1 is connected to a vehicle ECU (Electronic Control Unit) 71, an engine starter motor, and electrical loads 72 such as electrical components via external terminals 13A and 13B. When the starter motor is rotated and the vehicle is started, power storage device 1 discharges electricity, supplying power to electrical load 72.

[0081] The vehicle ECU 71 is a vehicle control unit that controls the vehicle. The vehicle ECU 71 controls an electrical load 72. Based on the estimation results regarding charge and discharge performance received from the estimation device 3, the vehicle ECU 71 controls the charge voltage and allowable charge and discharge amount of the power storage device 1 by controlling the electrical load 72. The vehicle ECU 71 is an example of a "host device."

[0082] The estimation device 3 includes a control unit 31, a storage unit 32, an input / output unit 33, and a communication unit 34. In this embodiment, the estimation device 3 is implemented using a circuit board. However, the estimation device 3 may alternatively be configured with multiple computers and perform distributed processing, or implemented using multiple virtual machines within a single server, or even a cloud server.

[0083] The control unit 31 is a computing circuit comprising a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU or GPU included in the control unit 31 executes various computer programs stored in the ROM and storage unit 32 to control the operation of the aforementioned hardware components. The control unit 31 may also include functions such as a timer for measuring the elapsed time from the issuance of a measurement start instruction to the issuance of a measurement end instruction, a counter for counting numbers, and a clock for outputting date and time information.

[0084] The storage unit 32 includes a nonvolatile storage device such as a flash memory or a hard disk drive. 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 estimation device 3.

[0085] The storage unit 32 of this embodiment stores an estimation program 321 for causing a computer to execute processing related to estimating the power supply performance of the power storage device 1; and estimation data 322, which is data required to execute the estimation program 321. The estimation data 322 includes the power storage element model used in the simulation. The power storage element model is described by configuration information indicating the circuit configuration and the values ​​of the components that make up the power storage element model. The storage unit 32 stores the configuration information indicating the circuit configuration of the power storage element model and the values ​​of the components that make up the power storage element model.

[0086] The computer program (program product) including the estimation program 321 can also be provided via a non-transitory recording medium 3A on which the computer program is readable. The recording medium 3A is, for example, a removable storage device such as a magnetic disk, an optical disk, or a semiconductor memory. The control unit 31 uses a reading device (not shown) to read the desired computer program from the recording medium 3A and causes the storage unit 32 to store the read computer program. Alternatively, the computer program can be provided via communication. The estimation program 321 can consist of a single computer program or multiple computer programs and can be executed on a single computer or on multiple computers interconnected via a communication network.

[0087] The input / output unit 33 includes an input / output interface for connecting to external devices. Connected to the input / output unit 33 are the disconnection circuit 62, the first temperature sensor 64, the second temperature sensor 65, the current sensor 66, and the voltage sensor 67. The control unit 31 constantly obtains temperature data measured by the first and second temperature sensors 64 and 65, current data measured by the current sensor 66, and voltage data measured by the voltage sensor 67 through the input / output unit 33. Furthermore, the control unit 31 outputs a control signal to the disconnection circuit 62 via the input / output unit 33, thereby switching the disconnection circuit 62 between an on and off state.

[0088] A display device such as a liquid crystal display device may be connected to the input / output unit 33. The control unit 31 outputs the estimation result of whether the power supply is possible via the input / output unit 33 and displays it on the display device.

[0089] Communication unit 34 includes a communication interface for communicating with external devices. Control unit 31 transmits and receives various data, including estimated power supply performance results, to and from the external devices via communication unit 34. The external device communicatively connected via communication unit 34 may also be a higher-level device (e.g., vehicle ECU 71).

[0090] The power supply performance estimation method of this embodiment will be described. To estimate power supply performance, estimation device 3 estimates the voltage behavior of power storage device 1 when energized according to a hypothetical energization pattern. Based on the estimated voltage behavior, it is estimated whether energization (power supply) according to the hypothetical energization pattern is possible. In this embodiment, the estimation method corrects the estimated voltage behavior value by taking into account the error in the estimated state value of power storage device 1 when estimating the voltage behavior. This improves the accuracy of determining whether energization according to the hypothetical energization pattern is possible. Following the description of the method for estimating whether energization is possible, the voltage behavior estimation method will be described in detail.

[0091] The estimation of whether energization is possible involves determining whether energization based on a specific assumed energization pattern is possible. For example, the estimation of whether energization based on the assumed energization pattern causes the voltage of the power storage device 1 to fall below a predetermined voltage threshold, or whether the current of the power storage device 1 exceeds the dischargeable current. The assumed energization pattern is, for example, a current pattern based on the current consumption of various electrical loads 72 mounted on a vehicle equipped with the power storage device 1, or a current pattern based on the energization time and the operating voltage range of the power storage device 1. The operating voltage range is, for example, a battery voltage threshold or a voltage threshold determined based on the electrical loads 72 mounted on the vehicle. During discharge, the lower limit voltage of the power storage device 1 is provided, while during charging, the upper limit voltage of the power storage device 1 is provided. The operating voltage range may also be a cell voltage threshold set for each power storage cell 2. The energization time, operating voltage range, and current value associated with the assumed energization pattern may be provided by a host device or pre-stored in the storage unit 32 as a pre-set assumed energization pattern.

[0092] Figure 4 This is a diagram showing an example of a hypothetical energization pattern. Figure 4 The graph shows time (in seconds (s)) on the horizontal axis, current (in amperes (A)) on the left vertical axis, and battery voltage (in V) on the right vertical axis. Values ​​increase as you move to the right on the horizontal axis, and increase as you move up on the vertical axis. On the left vertical axis, current decreases as you move downward, indicating a higher current discharge.

[0093] exist Figure 4 In FIG, the assumed energizing pattern shows a case where the battery is discharged at a current I1 for a period of t seconds. The battery voltage threshold is voltage value V1. The assumed energizing pattern is not limited to a pattern related to discharge; it may also be a pattern related to charge. Multiple assumed energizing patterns may be set.

[0094] Figure 5 This is a diagram illustrating a method for estimating whether or not energization can be performed based on an assumed energization pattern. Figure 5 In FIG. 1 , the upper graph shows the temporal change in the estimated voltage value of the power storage device 1 accompanying energization based on the assumed energization pattern, and the lower graph shows the result of estimating whether energization is possible. Figure 5 In the figure, it is shown whether the power storage device 1 can be used in the discharge state. Figure 4 The example of estimating the power supply when the power supply is supplied in the assumed power supply pattern shown in FIG. The estimating device 3 may also perform the estimation process stably (for example, every 1 second) when the power storage device 1 is in use. Figure 5 , estimated voltage values ​​of the power storage device 1 estimated at different estimation times t1 , t2 , and t3 , and estimation results of whether or not energization is possible are shown.

[0095] When the power storage device 1 is discharged at a predetermined current value based on the assumed energization pattern over a predetermined energization time, as shown in FIG. Figure 5 As shown above, the estimated voltage value of power storage device 1 decreases over time as it discharges. At each estimation time t1, t2, and t3, estimation device 3 estimates whether the estimated voltage value after energizing the assumed energizing pattern exceeds a predetermined operating voltage range (is below a preset lower voltage limit). If the estimated voltage value after energizing does not exceed the operating voltage range (is not below the lower voltage limit), it can be estimated that energizing is possible. If the estimated voltage value after energizing exceeds the operating voltage range (is below the lower voltage limit), it can be estimated that energizing is not possible.

[0096] As will be described in detail later, estimation device 3 provides the storage element model with an estimated state value representing the state of power storage device 1 at the estimated time, thereby determining an estimated voltage value after energization according to the assumed energization pattern. The estimated state value includes, for example, the SOC, internal resistance, and internal temperature of power storage device 1. The estimated state value of power storage device 1 changes over time. Based on the state of power storage device 1 at each estimated time, it is estimated whether energization is possible.

[0097] like Figure 5 As shown, at estimation time t1 and estimation time t2, estimated voltage values ​​Vt1 and Vt2 after energizing the assumed energizing pattern are greater than the lower limit voltage, and thus energization is estimated. At estimation time t3, estimated voltage value Vt3 after energizing the assumed energizing pattern is less than the lower limit voltage, and thus energization is estimated to be impossible.

[0098] A method of estimating an estimated voltage value used for estimating whether energization is possible will be described.

[0099] The estimation device 3 obtains an estimated voltage value of the power storage device 1 using the power storage element model. Figure 6 This is a circuit diagram showing an example of a storage element model. Figure 6 The power storage element model shown as an example in FIG. 1 is an equivalent circuit model, which simulates the charge and discharge behavior of the power storage cell 2 by combining the voltage source of the power storage cell 2 and circuit elements such as resistors and capacitors.

[0100] exist Figure 6 In the example shown, the equivalent circuit model includes a constant voltage source connected in series between the positive terminal and the negative terminal, a DC resistor for simulating a DC resistance component, and an RC parallel circuit for simulating transient polarization characteristics. Figure 6 , an equivalent circuit model in which two RC parallel circuits, namely a first RC parallel circuit and a second RC parallel circuit, are connected in series is shown, but the RC parallel circuit is not limited to a two-order circuit.

[0101] 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 power storage cell 2, which is expressed as V OCV . Open circuit voltage V OCV For example, it is provided as a function of SOC. OCV It can also be provided as a function of the actual capacitance of the power storage cell 2 .

[0102] The DC resistor simulates the DC resistance component (DC impedance) of the battery cell 2 and includes a resistance element R0. The resistance element R0 is provided as a value that varies depending on the current, voltage, SOC, internal temperature, and other factors. Once the impedance of the DC resistor is determined, the voltage generated across the DC resistor when current I flows through it in the equivalent circuit model can be calculated. The voltage generated across the DC resistor is referred to as the DC resistor voltage V. R0 .

[0103] The first RC parallel circuit is composed of a resistor element R1 and a capacitor element C1 connected in parallel. The second RC parallel circuit is composed of a resistor element R2 and a capacitor element C2 connected in parallel. The resistor elements R1, R2 and the capacitor elements C1, C2 constituting each RC parallel circuit are provided as values ​​that vary according to the current, SOC, internal temperature, etc. The impedance of the RC parallel circuit is determined based on the resistor elements R1, R2 and the capacitor elements C1, C2. If the impedance of the RC parallel circuit is determined, it is possible to calculate the voltage generated in the RC parallel circuit when the current I flows in the equivalent circuit model. The voltage generated in the RC parallel circuit is the polarization voltage V generated in the first RC parallel circuit. R1C1 The polarization voltage V generated in the second RC parallel circuit R2C2 The total voltage.

[0104] In the above equivalent circuit model, the terminal voltage (estimated voltage value) V of the power storage cell 2 generated when energization is performed in the assumed energization pattern is estimated. cell . t n Estimated voltage value of the power storage cell 2 at the time after 1 second) V cell Able to use open circuit voltage V OCV , current I, resistance elements R0, R1, R2, and capacitance elements C1, C2 are estimated by the following formula (1).

[0105] [Mathematical formula 1]

[0106]

[0107] In formula (1), the open circuit voltage V OCVFor example, an SOC-OCV table can be used to determine the SOC at the estimated time. The SOC at the estimated time can also be calculated using the current integration method. An SOC-OCV table can be created for each temperature, or a common table can be used. The current I can be the current value measured by current sensor 66. For example, current I is positive during charging and negative during discharging.

[0108] By calculating the estimated voltage value V of each power storage cell 2 obtained by equation (1), cell The voltage (estimated voltage value) V of the power storage device 1 is obtained by bat The estimated voltage value V of the power storage device 1 bat Alternatively, the estimated voltage value V of each power storage cell 2 may be used. cell The value obtained by subtracting the voltage drop caused by the structural resistance in the power storage device 1 from the total value of . The structural resistance is, for example, the resistance component of the conductive member.

[0109] The resistors R0, R1, and R2 and capacitors C1 and C2 (hereinafter referred to as circuit parameters) used in the equivalent circuit model are pre-determined based on actual measurement data, etc., depending on the purpose of the power storage device 1 being simulated. The circuit parameters are pre-stored in the storage unit 32 of the estimation device 3. The circuit parameters are stored, for example, in a data table format.

[0110] Figure 7 : is a conceptual diagram showing an example of a data table of circuit parameters. Figure 7 As shown in FIG. 1 , in the circuit parameter data table, circuit parameters are stored in association with, for example, the internal temperature, SOC, and current of the power storage device 1 . Figure 7 , a data table is shown for storing resistor element R0 for internal temperature, SOC, and current at each predetermined interval. Similarly, data tables are prepared for each circuit parameter other than resistor element R0, and each circuit parameter is set in association with internal temperature, SOC, and current.

[0111] Estimation device 3 acquires circuit parameters by communicating with an external device, for example, and stores the acquired circuit parameters in estimation data 322 of storage unit 32. The circuit parameter data table may be updated as appropriate based on the estimation result of the internal resistance value of power storage device 1.

[0112] The estimating device 3 estimates the voltage value V cell When estimating the voltage V, the circuit parameters corresponding to the internal temperature, SOC, and current of the power storage device 1 at the time of estimation are read from the data table. By substituting the read circuit parameters and other input values ​​into formula (1), the estimated voltage value V is obtained. cell .

[0113] By calculating the estimated voltage value V of each power storage cell 2 obtained by equation (1), cell The voltage (estimated voltage value) V of the power storage device 1 is obtained. bat .

[0114] Estimated voltage value V cell And the estimated voltage value V bat The estimated result depends on the internal resistance, internal temperature and SOC of the power storage device 1. The internal resistance, internal temperature and SOC of the power storage device 1 are values ​​indicating the state of the power storage device 1 and cannot be measured directly. bat The estimation of necessitates the use of an estimated state value obtained by estimating the state of the power storage device 1 .

[0115] The estimated state value can be estimated by various estimation functions. Estimation based on various estimation functions may not fully reflect the state of each power storage device 1, and estimation errors may occur. If the above-mentioned circuit parameters are calculated based on the internal temperature and SOC with errors, the circuit parameter values ​​will deviate, resulting in the estimated voltage value V bat Furthermore, if the internal resistance with error is used to estimate the voltage value V bat The estimated voltage value V bat Produce errors.

[0116] In addition, the output of the equivalent circuit model is also a kind of estimated state value. The equivalent circuit model may not be able to fully consider the characteristics of each storage cell 2. bat There is also an error between the voltage value obtained when power is actually supplied to the power storage device 1 .

[0117] By taking the error of the estimated state value into consideration, the estimated voltage value V can be estimated more appropriately. bat . It is possible to make the estimated voltage value V bat There are many types of errors in the estimated state values ​​that can cause errors. Therefore, it is necessary to comprehensively consider the individual voltage errors caused by the errors in the estimated state values. In this embodiment, the individual voltage errors caused by the errors in the estimated state values ​​are calculated based on the fact that the errors in the multiple estimated state values ​​are independent of each other (not dependent on each other). The individual voltage errors are equivalent to the estimated voltage value V bat The final voltage error is calculated by summing up the voltage errors obtained. The final voltage error is the error calculated for the estimated voltage value V. bat Correction value (V), recorded as ΔV error By using the correction value ΔV error To estimate the voltage value V bat Correction is performed to estimate the final estimated voltage value ΔVbat_error .

[0118] Since the errors of the multiple estimated state values ​​are not dependent on each other, the possibility that the errors of the estimated state values ​​will become the maximum error at the same time is extremely low. When the maximum error of each estimated state value is used, the correction value ΔV error If the correction value ΔV is calculated using only the error of the specific estimated state value, the power supply may be estimated to be unavailable earlier than it should be. error , then the correction value ΔV error The error of each estimated state value is calculated to determine the correction value ΔV. error , thereby making it possible to appropriately estimate the charge acceptance performance or discharge performance of the power storage device 1 without overestimating or underestimating.

[0119] The estimated error in voltage due to the error in SOC is referred to as SOC error and expressed as ΔV soc The estimated voltage error due to the internal resistance error is referred to as the internal resistance error and is expressed as ΔV Ri The estimated voltage error due to the internal temperature error is referred to as the temperature error and is expressed as ΔV Tcell . It will be caused by the estimated voltage value V bat The estimated voltage error that may occur from the voltage value when the power storage device 1 is actually energized is referred to as a model error and is expressed as ΔV model .

[0120] As an example, the correction value ΔV error Ability to use SOC error ΔV soc , internal resistance error ΔV Ri , temperature error ΔV Tcell And the model error ΔV model , which is expressed by the following formula (2).

[0121] [Mathematical formula 2]

[0122]

[0123] By using the correction value ΔV error To estimate the voltage value V bat Correction is performed to obtain the final estimated voltage ΔV of the power storage device 1 taking into account the error in the estimated state value. bat_error Estimated voltage ΔV bat_error The estimated voltage value V bat and voltage error ΔV error , as inferred from (3) below.

[0124]

[0125] As shown in the above formula (2), the correction value ΔV error In this embodiment, a single voltage error is obtained based on each estimated state value.

[0126] Figure 8 This diagram explains the method of estimating the SOC error. soc The SOC can be estimated based on data on the relationship between the time from the full charge point in time and the estimation error of the SOC. Figure 8 The graph shown shows an example of the above-mentioned relationship. Figure 8 The horizontal axis of the graph shown is time (unit: h), and the vertical axis is SOC estimation error (unit: %). The value increases toward the right of the horizontal axis and increases toward the top of the vertical axis.

[0127] As an example, the SOC of the power storage device 1 can be estimated using a current integration method. In the current integration method, the current values ​​flowing into and out of the power storage device 1 after full charge are integrated, using the SOC value at the last full charge state as a reference, to determine the SOC. In the current integration method, an SOC estimation error (%) occurs due to measurement error in the current sensor 66. Typically, if the SOC estimation error exceeds a predetermined threshold for full charge implementation, the SOC estimation error is reset by fully charging the power storage device 1. The SOC estimation error can be reset, for example, by estimating the SOC using the OCV method (performing an OCV reset). The OCV method is a method for determining the SOC based on the OCV of the power storage device 1, based on the correlation between the SOC and OCV.

[0128] like Figure 8 As shown, the SOC estimation error (%) tends to increase as the time elapsed from a predetermined timing (reference time) increases. The predetermined timing refers to the last (most recent) full charge time, i.e., the time at which the last error was reset. Data is generated to reflect this trend by relating the time elapsed from the full charge time to the SOC estimation error. By pre-storing this generated relationship data, the SOC estimation error can be calculated based on this relationship data and the time elapsed from the last full charge time.

[0129] Because the relationship between the time since full charge and the SOC estimation error varies depending on the internal temperature of power storage device 1, the internal temperature history of power storage device 1 may be considered when determining the SOC estimation error. For example, the lower the internal temperature of power storage device 1, the greater the self-discharge amount of power storage device 1, and therefore, it can be estimated that the SOC estimation error increases.

[0130] By calculating the estimated voltage value V when using the SOC value taking into account the estimation error of the SOC bat The estimated voltage value V is the same as that in the case of using the SOC value without considering the estimation error of the SOC. bat The difference between the two can be used to calculate the SOC error ΔV soc In the following description, the estimated voltage value V is considered when the estimation error of the estimated state value such as SOC is taken into account. bat The estimated state value taking into account the estimated error is obtained by applying it to the equivalent circuit model. The estimated state value taking into account the estimated error is, for example, an SOC obtained by adding or subtracting the estimated error from the SOC calculated by the current integration method.

[0131] Internal resistance error ΔV Ri Similarly, internal resistance estimation can be performed based on data showing the relationship between the time since a predetermined timing (reference time) and the internal resistance estimation error. The predetermined timing (reference time) refers to the time when the internal resistance was last estimated. More specifically, it refers to the time when the internal resistance was last estimated under conditions where the internal resistance can be estimated with high accuracy. The internal resistance estimation error (mΩ) of the power storage device 1 tends to increase as the time elapsed since the last internal resistance estimation. Data showing the relationship between the time since the last internal resistance estimation and the internal resistance estimation error is generated to reflect this trend. By pre-storing this generated relationship data, the internal resistance estimation error can be calculated based on this relationship data and the time elapsed since the last internal resistance estimation. The time when the internal resistance can be estimated under conditions where the internal resistance can be estimated with high accuracy may be, for example, the time when a current amount suitable for internal resistance estimation flows during engine cranking (starting the engine by rotating the engine shaft) or during high-voltage system startup.

[0132] Because the relationship between the time since the internal resistance was estimated and the internal resistance estimation error varies depending on the internal temperature of power storage device 1, the internal temperature history of power storage device 1 may be considered when determining the internal resistance estimation error. For example, the lower the internal temperature of power storage device 1, the greater the degree of deterioration of power storage device 1, and therefore, it may be estimated that the internal resistance estimation error increases.

[0133] By calculating the estimated voltage value V when using the internal resistance value taking into account the estimation error of the internal resistance bat The estimated voltage value V is different from the estimated voltage value V when the internal resistance value is used without considering the estimation error of the internal resistance. bat The internal resistance error ΔV is calculated by Ri .

[0134] Figure 9 This is a diagram explaining a method for estimating a temperature error caused by current flow. Figure 10 This diagram explains how to estimate the temperature error caused by changes in ambient temperature. Tcell Includes: the first temperature error ΔV caused by the amount of current (charge and discharge amount) associated with actual charging or discharging Tcell , and a second temperature error ΔV caused by a change in the ambient temperature of the power storage device 1 Tcell .

[0135] use Figure 9 , for the first temperature error ΔV Tcell The first temperature error ΔV is described below. Tcell The internal temperature can be estimated based on data on the relationship between the amount of current supplied to the power storage device 1 and the estimation error. Figure 9 The graph shown shows an example of the above-mentioned relationship. Figure 9 The horizontal axis of the graph shows the difference between the temperature of the energized heating element and the ambient temperature (in degrees Celsius), representing the amount of current flowing through power storage device 1. The vertical axis shows the estimated error in the internal temperature (in degrees Celsius). The values ​​increase toward the right of the horizontal axis, and increase toward the top of the vertical axis.

[0136] In this embodiment, the amount of current flowing into the power storage device 1 is determined using the temperature (measured temperature value) of the current-carrying heating element measured by the second temperature sensor 65. As described above, the temperature of the current-carrying heating element changes in accordance with the amount of current flowing into the power storage device 1. The greater the difference between the temperature of the current-carrying heating element and the ambient temperature measured by the first temperature sensor 64, the greater the amount of current flowing into the power storage device 1. Alternatively, the amount of current flowing into the power storage device 1 can be determined based on the amount of current measured by the current sensor 66 and the voltage sensor 67, for example.

[0137] Because the internal temperature (cell temperature) of power storage device 1 cannot be measured directly, the ambient temperature (measured temperature value) obtained by first temperature sensor 64 is used as the temperature associated with power storage device 1. When power is supplied to power storage device 1, the internal temperature rises rapidly in response to heat generated within power storage device 1. Meanwhile, it takes time for the temperature measured by first temperature sensor 64 to reach the same value as the internal temperature. The deviation between the internal temperature and the temperature measured by first temperature sensor 64 constitutes the estimated error (°C) in the internal temperature.

[0138] like Figure 9As shown, as the difference between the temperature of the energized heating element and the ambient temperature, that is, the amount of current supplied to the power storage device 1, increases, the estimated error in the internal temperature tends to increase. Data is generated to reflect this trend, showing the relationship between the amount of current supplied and the estimated error in the internal temperature. The estimated error in the internal temperature is calculated based on the generated relationship data and the amount of current supplied at the time of estimation. In this way, by installing a first temperature sensor 64 for detecting the temperature of a conventional power storage device 1 and a second temperature sensor 65 for correcting the temperature error in the power storage device 1, the estimated error in the internal temperature can be calculated with high accuracy.

[0139] When the amount of current flowing is relatively small, the estimated error of the internal temperature is considered to be small. Figure 9 As shown, a threshold value for the occurrence of an estimation error of the internal temperature may be set in advance. The estimation error of the internal temperature may be estimated only when the amount of energization at the estimation time is equal to or greater than the threshold value for the occurrence of the estimation error.

[0140] By calculating the estimated voltage value V when using the internal temperature value taking into account the estimation error of the internal temperature bat The estimated voltage value V is different from the estimated voltage value V when the internal temperature value without considering the estimation error of the internal temperature is used. bat The difference between the two, thus obtaining the first temperature error ΔV Tcell .

[0141] use Figure 10 , indicating the second temperature error ΔV Tcell The second temperature error ΔV Tcell The internal temperature can be estimated based on data on the relationship between the amount of change in the ambient temperature of the power storage device 1 and the estimation error. Figure 10 The graph shown shows an example of the above-mentioned relationship. Figure 10 The horizontal axis of the graph shown is per unit time (in Figure 10 In this example, the vertical axis represents the change in ambient temperature (in °C) over a period of 10 minutes (in °C). The vertical axis represents the estimated error in internal temperature (in °C). Values ​​increase toward the right of the horizontal axis, and increase toward the top of the vertical axis.

[0142] When the ambient temperature of the power storage device 1 changes drastically, the temperature value measured by the first temperature sensor 64 changes to near the ambient temperature relatively quickly, while it takes time for the interior of the power storage device 1 to reach the same temperature as the ambient temperature.

[0143] like Figure 10As shown, as the change in ambient temperature increases, the internal temperature estimation error tends to increase. Data is generated to reflect this trend, showing the relationship between the change in ambient temperature and the internal temperature estimation error. The internal temperature estimation error is calculated based on the generated relationship data and the change in ambient temperature at the time of estimation.

[0144] By calculating the estimated voltage value V when using the internal temperature value taking into account the estimation error of the internal temperature bat The estimated voltage value V is different from the estimated voltage value V when the internal temperature value without considering the estimation error of the internal temperature is used. bat The difference between the two, thus obtaining the second temperature error ΔV Tcell .

[0145] In the power storage device 1, since the first temperature error ΔV is estimated Tcell and the second temperature error ΔV Tcell The possibility of simultaneous occurrence is low, so when calculating the correction value ΔV error When the first temperature error ΔV is used, Tcell and the second temperature error ΔV Tcell For example, when the amount of current flowing at the estimation time is equal to or greater than the threshold value for occurrence of the estimation error, the first temperature error ΔV may be used. Tcell Calculate the correction value ΔV error When the current flow at the estimated time is lower than the threshold value for the occurrence of the estimation error, the second temperature error ΔV is used. Tcell Calculate the correction value ΔV error .

[0146] Model error ΔV model The power storage device 1 and the model error ΔV can be used to model The above-mentioned relational data can also be generated by finding the difference between a voltage value obtained as a result of a current-carrying test on a battery under the same conditions as those of the equivalent circuit model and an estimated voltage value estimated from the equivalent circuit model.

[0147] When the energization time of the energization mode is assumed to be short, the estimation accuracy of the estimated voltage value based on the equivalent circuit model is high, and the model error ΔV model When the energization time of the energization mode is assumed to be long, the increase in the diffusion resistance of the storage cell 2 cannot be considered in the equivalent circuit model, so the estimation accuracy of the estimated voltage value based on the equivalent circuit model is low, and the model error ΔV model There is a tendency to increase. Generate the error ΔV between the power storage device 1 and the model model Based on the generated data of the above relationship, the model error ΔV for the power storage device 1 is obtained.model Regarding the power storage device 1 and the model error ΔV model As for the relational data, it can also be obtained by considering at least one of the magnitude of the current, the magnitude of the current change and the number of times of the assumed energization mode instead of or on the basis of the energization time of the assumed energization mode.

[0148] Due to the model error ΔV model Since the power supply time of the assumed power supply pattern changes accordingly, the power storage device 1 and the model error ΔV model The data of the relationship can also be set by considering the energization time of the assumed energization mode. The above relationship is set as the model error ΔV model Alternatively, the above relationship may be set as the model error ΔV model The above relationship can also be set as the model error ΔV model The above relationship can also be set as the model error ΔV model The value increases as the number of energizations based on the assumed energization pattern increases.

[0149] Even if the power storage cell 2 is polarized before the power supply performance is estimated, the model error ΔV model There is also a tendency to increase. The power storage device 1 and the model error ΔV model The data of the relationship between the model error ΔV can also be set by considering the charge and discharge history before the estimated time. model The above relationship can be set as the model error ΔV model As the charge and discharge current value increases, the above relationship can also be set as the model error ΔV model It increases as the charge and discharge time becomes longer.

[0150] The estimation device 3 obtains the various relationship data described above and pre-stores the obtained relationship data in the estimated data 322 of the storage unit 32. The various relationship data may be stored, for example, as a graph, table, or functional expression representing each relationship. The various relationship data can be generated, for example, by conducting a power-on test in advance. The relationship data may also be generated by conducting a power-on test using the same test unit as the power storage device 1 for which the power supply performance is to be estimated, or a test unit having a similar structure, type, or composition to the power storage device 1.

[0151] like Figure 5As explained in , by setting the correction value ΔV error The estimated voltage after correction ΔV bat_error The voltage is compared with the preset lower or upper limit voltage to determine whether power can be supplied.

[0152] In the above description, the estimated voltage value V is obtained based on the measurement data of the current, voltage, and temperature of the power storage device 1 obtained by various sensors and the equivalent circuit model. cell And the estimated voltage value V bat Instead, the estimated voltage value V cell And the estimated voltage value V bat It can also be determined based on an estimated value of the internal temperature, SOC, SOH, etc., and an equivalent circuit model.

[0153] Figure 11 as well as Figure 12 This is a flowchart illustrating an example of a processing procedure performed by the estimation device 3. The processing in the following flowchart may be executed by the control unit 31 in accordance with the estimation program 321 stored in the storage unit 32 of the estimation device 3, or may be implemented by a dedicated hardware circuit (e.g., an FPGA or ASIC) included in the control unit 31, or may be implemented by a combination of these.

[0154] The control unit 31 of the estimation device 3, functioning as an acquisition unit, begins acquiring measurement data of the current, voltage, and temperature of the power storage device 1 (step S11). The measurement data includes the measured current value based on the current sensor 66, the measured voltage value based on the voltage sensor 67, the measured temperature value of the ambient temperature based on the first temperature sensor 64, and the measured temperature value of the temperature of the energized heating element based on the second temperature sensor 65. Subsequently, the control unit 31 acquires the measurement data at predetermined or appropriate intervals and stores the acquired measurement data in the storage unit 32. Thus, time-series measurement data is collected. The acquisition of measurement data may also mean reading the measurement data stored in the storage unit 32.

[0155] The control unit 31 may also obtain the SOC of the power storage device 1 by, for example, a current integration method in response to the acquisition of the measurement data. The control unit 31 may also obtain the open circuit voltage V corresponding to the SOC at the time of measurement based on the obtained SOC and the SOC-OCV table stored in the estimated data 322. OCV .

[0156] The control unit 31 obtains an assumed energization pattern for power supply performance estimation (step S12 ). The control unit 31 may obtain the assumed energization pattern by, for example, receiving the energization current value, energization time, and upper or lower voltage limits transmitted from a host device.

[0157] The control unit 31 determines whether to estimate the power supply performance (step S13). For example, if the control unit 31 determines not to estimate the power supply performance because the predetermined estimation timing is not reached (step S13: NO), the control unit 31 returns to step S13 and waits until the estimation timing is reached.

[0158] When it is determined that the power supply performance is estimated based on the preset estimation timing (step S13: YES), the control unit 31 estimates the estimated voltage value V of the power storage device 1 when energized in the assumed energization pattern by functioning as an estimating unit. bat (Step S14 ). The control unit 31 estimates the estimated voltage value V of each power storage cell 2 using the measured current value, measured voltage value, and measured temperature value of the ambient temperature at the estimation time using the equivalent circuit model. cell The control unit 31 calculates the estimated voltage value V of each power storage cell 2. cell The estimated voltage value V of the power storage device 1 is obtained by bat The circuit parameters used in the equivalent circuit model are obtained based on the measured current value at the estimation time, the measured temperature value of the ambient temperature, and the SOC value based on the current integration. bat This is a voltage value that does not take into account errors in various estimated state values.

[0159] The control unit 31 derives the time elapsed since the last full charge based on the charge and discharge history of the power storage device 1 (step S15). The control unit 31 derives the SOC estimation error corresponding to the derived elapsed time based on the data on the relationship between the time elapsed since the full charge and the SOC estimation error stored in the storage unit 32 (step S16).

[0160] The control unit 31 calculates the estimated voltage value V by taking into account the estimation error of the estimated SOC. bat The estimated voltage value V is different from the estimated voltage value V when the estimation error of the SOC estimated in step S14 is not considered. bat The difference between the two is used to estimate the SOC error ΔV soc (Step S17).

[0161] The control unit 31 derives the time elapsed since the last internal resistance estimation based on the charge and discharge history of the power storage device 1 (step S18). The control unit 31 derives the internal resistance estimation error corresponding to the derived elapsed time based on the data on the relationship between the time since the internal resistance estimation and the internal resistance estimation error stored in the storage unit 32 (step S19).

[0162] The control unit 31 calculates the estimated voltage value V by taking into account the estimation error of the estimated internal resistance.bat The estimated voltage value V is different from the estimated voltage value V when the estimation error of the internal resistance estimated in step S14 is not considered. bat The internal resistance error ΔV is estimated by Ri (Step S20).

[0163] The control unit 31 determines whether the temperature difference between the ambient temperature and the temperature of the heating element is greater than a predetermined threshold value for generating an estimated error in the internal temperature (step S21). The temperature difference between the ambient temperature and the temperature of the heating element is obtained by calculating the difference (the absolute value of the difference) between the ambient temperature measured by the first temperature sensor 64 and the temperature of the heating element measured by the second temperature sensor 65.

[0164] If the temperature difference is determined to be below the estimation error threshold (step S21: NO), the control unit 31 derives the internal temperature estimation error based on the relationship data between the change in ambient temperature and the internal temperature estimation error stored in the storage unit 32 (step S22). The control unit 31 calculates the change in ambient temperature per unit time based on the time-series measurement data stored in the storage unit 32, and determines the internal temperature estimation error corresponding to the calculated change in ambient temperature based on the relationship data.

[0165] The control unit 31 calculates the estimated voltage value V by taking into account the estimation error of the estimated internal temperature. bat The estimated voltage value V is different from the estimated voltage value V when the estimation error of the internal temperature estimated in step S14 is not considered. bat The difference is estimated as the temperature error ΔV Tcell The second temperature error ΔV Tcell (Step S23).

[0166] If the temperature difference is determined to be greater than the estimation error threshold (step S21: YES), the control unit 31 derives the estimated internal temperature error based on the relationship data between the amount of current (the difference between the temperature of the energized heating element and the ambient temperature) and the estimated internal temperature error stored in the storage unit 32 (step S24). The control unit 31 calculates the estimated internal temperature error corresponding to the calculated temperature difference based on this relationship data.

[0167] The control unit 31 calculates the estimated voltage value V by taking into account the estimation error of the estimated internal temperature. bat The estimated voltage value V is different from the estimated voltage value V when the estimation error of the internal temperature estimated in step S14 is not considered. bat The difference is estimated as the temperature error ΔV Tcell The first temperature error ΔV Tcell(Step S25).

[0168] The control unit 31 is based on the difference between the power storage device 1 and the model error ΔV stored in the storage unit 32. model The relationship between the data, the estimated model error ΔV model (Step S26).

[0169] In step S26, the control unit 31 may determine the relational data to be used based on the length of the energization time of the assumed energization pattern, and estimate the model error ΔV using the determined relational data. model The control unit 31 may correct the estimated model error ΔV using a correction coefficient corresponding to the length of the energization time of the assumed energization pattern. model , so that the model error ΔV model Increases in accordance with the length of the energization time.

[0170] In step S26, the control unit 31 may determine the relational data to be used based on the most recent charge and discharge history before the estimation time, and estimate the model error ΔV using the determined relational data. model The control unit 31 may also correct the estimated model error ΔV using a correction coefficient corresponding to the most recent charge and discharge history. model , so that the model error ΔV model It increases in accordance with charge and discharge.

[0171] The control unit 31 calculates the estimated SOC error ΔV based on the estimated SOC error ΔV. soc , internal resistance error ΔV Ri , temperature error ΔV Tcell , and model error ΔV model , to estimate the correction value ΔV error (Step S27 ) Regarding the correction value ΔV error As an example, the SOC error ΔV soc , internal resistance error ΔV Ri , temperature error ΔV Tcell , and model error ΔV model The value of the root of the sum of their respective squares.

[0172] The control unit 31 functions as a correction unit and uses the estimated correction value ΔV error , the estimated voltage value V estimated in step S14 bat Correction is performed to estimate the final estimated voltage value ΔV of the power storage device 1 bat_error (Step S28).

[0173] The control unit 31 calculates the estimated voltage value ΔV based on the estimated voltage value ΔV. bat_error, it is estimated whether the power storage device 1 can be energized in the assumed energization pattern (step S29). The control unit 31 determines the estimated voltage value ΔV bat_error Whether energization is possible is estimated by determining whether the voltage exceeds the operating voltage range of the assumed energization mode.

[0174] The control unit 31 outputs information based on the estimation result to the host device via the communication unit 34 (step S30), and ends the series of processing. As information based on the estimation result, the control unit 31 can output the estimated voltage value ΔV bat_error And whether it can be powered on, at least one of them can also be output.

[0175] The control unit 31 determines whether to terminate the estimation process (step S31). For example, if the estimation process is not terminated because the specified termination action has not been performed (step S31: "NO"), the control unit 31 returns to step S13 and repeats the estimation process. If the estimation process is terminated because the specified termination action has been performed (step S31: "YES"), the control unit 31 terminates the series of processes.

[0176] In the above process, the SOC error ΔV is not limited. soc , internal resistance error ΔV Ri , temperature error ΔV Tcell , and model error ΔV model The estimation process of each error can also be performed in a different order, or can be processed in parallel.

[0177] According to the present embodiment, the estimated voltage value of the power storage device 1 is corrected based on the error in the estimated state value of the power storage device 1 , thereby enabling the power supply performance of the power storage device 1 to be estimated with high accuracy.

[0178] The estimation device, estimation method, and estimation program can be applied to applications other than vehicles. They can be applied to flying objects such as aircraft, flying vehicles, and HAPS (High Altitude Platform Stations), as well as ships and submarines. While preferably applied to mobile objects requiring a high degree of safety (and real-time calculations), the estimation device, estimation method, and estimation program are not limited to mobile objects and can also be applied to stationary power storage devices.

[0179] The embodiments disclosed herein are illustrative in all respects and should not be construed as restrictive. The technical features described in the embodiments can be combined with each other, and the scope of the present invention is intended to include all modifications within the claims and the scope equivalent to the claims.

[0180] The sequence shown in each embodiment is not limited. Within the scope of consistency, the processing procedures may be performed in a different order. In addition, multiple processes may be performed in parallel. The processing subject of each process is not limited. Within the scope of consistency, the processing of each device may be performed by another device.

[0181] The matters described in each embodiment can be combined with each other. Furthermore, independent claims and dependent claims described in the claims can be combined with each other in all combinations, regardless of the format in which they are cited. Furthermore, although the claims use a format in which a claim refers to two or more other claims (a multi-claim format), this is not limited to this format. A format in which a claim refers to at least one multi-claim (a multi-multi claim) can also be used.

[0182] Description of Reference Numerals

[0183] 1: Power storage device (power storage element), 2: Power storage cell, 3: Estimation device, 31: Control unit, 32: Storage unit, 33: Input / output unit, 34: Communication unit, 321: Estimation program, 322: Estimation data, 3A: Recording medium.

Claims

1. A method of inference, wherein: Using a storage element model that simulates the behavior of the storage element, an estimated voltage value of the storage element when energized according to an assumed energization pattern is estimated; The estimated voltage value is corrected based on a correction value obtained based on an error in the estimated state value of the power storage element.

2. The estimation method according to claim 1, wherein: obtaining a measured current value, a measured voltage value, and a measured temperature value of the storage element; The estimated voltage value is estimated using the acquired measured current value, measured voltage value, and measured temperature value and the energy storage device model.

3. The estimation method according to claim 1 or claim 2, wherein: The correction value is determined to be smaller than the sum of individual correction values ​​determined based on maximum errors of a plurality of estimated state values ​​in the power storage element.

4. The estimation method according to claim 1 or claim 2, wherein: Among the plurality of estimated state values, an error in an estimated state value having a longer elapsed time from a predetermined timing is increased.

5. The estimation method according to claim 1 or claim 2, wherein: The error of the internal temperature of the energy storage element in the estimated state value increases according to the magnitude of the change in the ambient temperature of the energy storage element or the magnitude of the amount of energization.

6. The estimation method according to claim 1 or claim 2, wherein: An error in the output of the energy storage device model in the estimated state value is increased based on at least one of a length of energization time, a magnitude of current, and a magnitude and number of current fluctuations in the assumed energization pattern.

7. The estimation method according to claim 1 or claim 2, wherein: The power storage element is a power storage unit having a plurality of power storage cells. obtaining a measured voltage value and a measured temperature value of each of the plurality of power storage cells, An estimated voltage value of the power storage unit is obtained based on an estimated voltage value of each of the plurality of power storage cells estimated using the acquired measured voltage values ​​and measured temperature values ​​of each of the plurality of power storage cells.

8. The estimation method according to claim 1 or claim 2, wherein: Based on the estimated voltage value and the correction value, it is estimated whether or not the power storage element can be charged or discharged based on the assumed energization pattern.

9. An inference program for causing a computer to execute the following processing: estimating an estimated voltage value of the power storage element when energized according to an assumed energization pattern using a power storage element model that simulates the behavior of the power storage element; and The estimated voltage value is corrected based on a correction value obtained based on an error in the estimated state value of the power storage element.

10. An estimation device comprising: an estimating unit that estimates an estimated voltage value of the power storage element when energized according to an assumed energization pattern, using a power storage element model that simulates the behavior of the power storage element; and The correction unit corrects the estimated voltage value based on a correction value obtained based on an error in the estimated state value of the power storage element. 11 . A power storage device comprising the estimation device according to claim 10 .

Images