Power supply

Abstract

To estimate a reduction amount of an electrolytic solution of a secondary cell with high accuracy.SOLUTION: A cell ECU acquires a voltage Vb and a current Ib of each cell, and a temperature Tb of each cell, a temperature sensor of each cell from a voltage monitoring module, a current sensor, and a temperature sensor, respectively (acquires detected data). The cell ECU determines, on the basis of the current Ib, whether the detected data are detected when a battery 11 is energized or when preserved. If the detected data are as of the battery-energized time, the cell ECU calculates an index Ea1 by referring to a first map using the voltage Vb and the temperature Tb as arguments. Meanwhile, if the detected data are as of the battery-preserved time, the cell ECU calculates the index Ea1 by referring to a second map, using the voltage Vb and the temperature Tb as arguments. Then, the cell ECU adds the index Ea1 or an index Ea2 to an index Easum as a reduction amount of an electrolytic solution in a unit time of this time.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a power supply device. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2017-157280 (Patent Document 1) discloses a battery pack that detects the amount of gas generated by decomposition of a non-aqueous electrolyte in a lithium ion battery, and estimates the amount of decomposition of the non-aqueous electrolyte based on the detected amount of gas and a predetermined correlation between the amount of decomposition of the non-aqueous electrolyte and the amount of gas generated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-157280 A [Patent Document 2] JP 2021-061119 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, it is known that in a secondary battery having an electrode assembly with a relatively large aspect ratio and in which the electrodes and the separator are bonded together, gas generated by decomposition of the electrolyte tends to remain in the electrode assembly. Therefore, the technology disclosed in Patent Document 1 may not be able to accurately estimate the amount of decomposition (reduction) of the electrolyte in a secondary battery containing such an electrode assembly.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to accurately estimate the amount of electrolyte reduction in a secondary battery. [Means for solving the problem]

[0006] (1) A power supply device according to the present disclosure includes a secondary battery having an electrolyte, a detection device for detecting the voltage and temperature of the secondary battery, a storage device for storing first information indicating a relationship between the voltage of the secondary battery, the temperature of the secondary battery, and an amount of electrolyte reduction when the secondary battery is energized, and second information indicating a relationship between the voltage of the secondary battery, the temperature of the secondary battery, and an amount of electrolyte reduction when the secondary battery is stored, and a control device for calculating a first index indicating an amount of electrolyte reduction. The first index includes a second index indicating an amount of electrolyte reduction due to energization of the secondary battery, and a third index indicating an amount of electrolyte reduction due to storage of the secondary battery. The control device calculates the second index based on the voltage and temperature detected by the detection device and the first information when the secondary battery is energized, and calculates the third index based on the voltage and temperature detected by the detection device and the second information when the secondary battery is stored.

[0007] According to the above configuration, when the secondary battery is energized, the second index is calculated based on the detected voltage and temperature and the first information, and when the secondary battery is stored, the third index is calculated based on the detected voltage and temperature and the second information. The first index indicating the amount of electrolyte reduction is calculated by integrating the second index and the third index, and the amount of electrolyte reduction can be estimated based on the first index. In this way, the amount of electrolyte reduction can be estimated using the detected voltage and temperature, so that the amount of electrolyte reduction can be accurately estimated for various secondary batteries having electrolyte.

[0008] (2) In one embodiment, the first information is created based on the results of a cycle test of the secondary battery performed for each temperature, and the second information is created based on the results of a storage test of the secondary battery performed for each temperature and voltage.

[0009] According to the above configuration, the first information and the second information can be appropriately created. Therefore, by using the first information and the second information, the second index and the third index can be calculated with high accuracy. Therefore, the first index can be calculated with high accuracy, and the reduction amount of the electrolyte of the secondary battery can be estimated with high accuracy.

[0010] (3) In one embodiment, the control device outputs a command to issue a warning when the first indicator is equal to or greater than a first threshold value.

[0011] The first threshold is set to, for example, a value that indicates that the electrolyte is zero plus a certain margin. When the first indicator is equal to or greater than the first threshold, a command to issue a warning is output, so that a warning can be issued to the user.

[0012] (4) In one embodiment, the control device outputs a command to limit the input / output power of the secondary battery when the first indicator is less than a first threshold and is equal to or greater than a second threshold that is smaller than the first threshold.

[0013] According to the above configuration, even if the first index is less than the first threshold value, if it is equal to or greater than the second threshold value, the input / output power of the secondary battery is limited, so that the decrease in the electrolyte can be slowed down.

[0014] (5) In one embodiment, the control device outputs a command to limit an upper limit voltage value of the secondary battery when the first indicator is less than the second threshold and greater than or equal to a third threshold that is smaller than the second threshold.

[0015] According to the above configuration, even if the first index is less than the second threshold value, if it is equal to or greater than the third threshold value, the upper limit voltage value of the secondary battery is limited, so that the decrease in the electrolyte can be slowed down.

[0016] (6) In one embodiment, the secondary battery includes an electrode assembly having an aspect ratio of 1.5 or more. The electrode assembly is configured by laminating a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The separator includes a functional layer having a function of bonding the positive electrode and the negative electrode to the separator.

[0017] The amount of electrolyte reduction can be estimated with high accuracy even in a secondary battery having an electrode assembly in which the aspect ratio is relatively large (1.5 or more) and the electrodes and the separator are bonded together. Effect of the Invention

[0018] According to the present disclosure, the amount of electrolyte reduction in a secondary battery can be estimated with high accuracy. [Brief description of the drawings]

[0019] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle according to an embodiment; [Diagram 2] FIG. 2 is a diagram for explaining the configuration of a battery in detail. [Diagram 3] FIG. 2 is a diagram for explaining a method for creating a first map. [Figure 4] FIG. 4 is a diagram showing an example of a first map. [Diagram 5] 13 is a flowchart showing an estimation process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters, and the description thereof will not be repeated.

[0021] <Overall configuration of the power system> FIG. 1 is a diagram showing a schematic configuration of a vehicle 1 according to the present embodiment. The vehicle 1 according to the present embodiment is an electric vehicle (BEV: Battery Electric Vehicle) configured to be capable of DC charging, which receives a supply of DC power from a power source (not shown) external to the vehicle and charges an on-board battery 11. The type of the vehicle 1 is not limited to an electric vehicle as long as it is a vehicle equipped with a battery pack. The vehicle 1 may be a hybrid vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle), or a fuel cell electric vehicle (FCEV: Fuel Cell Electric Vehicle). The vehicle 1 may also be configured to be capable of AC charging, which receives a supply of AC power from a power source external to the vehicle and charges an on-board battery 11.

[0022] The vehicle 1 includes a battery pack 10, a power control unit (hereinafter also referred to as “PCU (Power Control Unit)”) 30, a motor generator 40, a power transmission gear 50, drive wheels 55, an inlet 60, an alarm device 70, and an ECU (Electronic Control Unit) 80.

[0023] The battery pack 10 and the PCU 30 are electrically connected by power lines PL1 and NL1. The battery pack 10 includes a battery 11, a system main relay (SMR) device 13, a voltage monitoring module 16, a current sensor 17, a temperature sensor 18, and a battery ECU 20. The battery pack 10 corresponds to an example of a "power supply device" according to the present disclosure.

[0024] The battery 11 is mounted on the vehicle 1 as a driving power source (i.e., a power source). The battery 11 is configured to include a plurality of stacked cells 12. The cells 12 are, for example, secondary cells such as nickel-metal hydride cells or lithium-ion cells. The cell 12 may be any cell having a liquid electrolyte (electrolytic solution) between a positive electrode and a negative electrode, and may be either a non-aqueous electrolyte cell or an aqueous electrolyte cell.

[0025] Fig. 2 is a diagram for explaining in detail the configuration of the battery 12. In Fig. 2, the battery 12 is shown in a see-through manner with its interior seen through. The battery 12 includes a case 121, a cover 122, a positive terminal 123, a negative terminal 124, and an electrode body 125 (shown by a dashed line).

[0026] Housing 121 has a square shape (approximately a rectangular parallelepiped shape). In the following, the long side direction (width direction) of housing 121 is defined as the x-axis direction, the depth direction (thickness direction) is defined as the y-axis direction, and the short side direction (height direction) is defined as the z-axis direction.

[0027] Lid 122 seals the upper surface of housing 121. One end of each of positive terminal 123 and negative terminal 124 protrudes to the outside from lid 122. The other end of each of positive terminal 123 and negative terminal 124 is electrically connected to an internal positive terminal and an internal negative terminal (neither shown) inside housing 121, respectively.

[0028] 2, with the top surface sealed by the lid 122, the housing 121 has a housing width Wx, a housing depth (thickness) Wy, and a housing height Wz (excluding the positive electrode terminal 123 and the negative electrode terminal 124). The aspect ratio Ar of the battery 12 according to this embodiment is expressed by the following formula (1).

[0029] Aspect ratio Ar = housing width Wx / housing height Wz (1) The housing 121 of the battery 12 according to the present embodiment is configured to have an aspect ratio Ar of 1.5 or more. Furthermore, the electrode body 125 housed in the housing 121 is also configured to have an aspect ratio of 1.5 or more.

[0030] The electrode body 125 is formed by stacking a positive electrode 126 and a negative electrode 127 with a separator 128 interposed therebetween, and winding the laminate. The electrode body 125 is housed in the case 121 such that the winding axis extends in the width direction (x-axis direction) of the case 121. The electrolyte is injected into the case 121 and impregnated into the electrode body 125, and is mainly held inside the electrode body 125. Note that, although an example in which the electrode body 125 is a wound type is shown in FIG. 2, the electrode body 125 may be a laminated type.

[0031] The positive electrode 126, the negative electrode 127, the separator 128, and the electrolyte may have a structure and materials known for the positive electrode, the negative electrode, the separator, and the electrolyte of a lithium ion secondary battery, respectively. The separator 128 is configured to include a binder having an adhesive function, such as polyvinylidene fluoride (PVdF).

[0032] 1 again, the system main relay device 13 is provided on the power lines PL1, NL1 that electrically connect the battery 11 and the PCU 30. The system main relay device 13 includes SMRs 14, 15. One end of the SMR 14 is electrically connected to the positive terminal of the battery 11, and the other end is electrically connected to the PCU 30. One end of the SMR 15 is electrically connected to the negative terminal of the battery 11, and the other end is electrically connected to the PCU 30.

[0033] The voltage monitoring module 16 detects the voltage Vb of each of the multiple cells 12 included in the battery 11, and outputs to the battery ECU 20 a signal indicating the detection result.

[0034] The current sensor 17 is provided between the positive terminal of the battery 11 and the SMR 14, and detects a current Ib input to and output from the battery 11. The current sensor 17 outputs to the battery ECU 20 a signal indicating the detection result.

[0035] The temperature sensor 18 detects the temperature Tb of each of the plurality of cells 12 included in the battery 11, and outputs a signal indicating the detection result to the battery ECU 20.

[0036] The battery ECU 20 includes a processor 21 such as a CPU (Central Processing Unit), a memory 22 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output port (not shown) for inputting and outputting various signals. The battery ECU 20 manages the battery 11 in cooperation with the ECU 80 based on input of signals from each sensor (the voltage monitoring module 16, the current sensor 17, the temperature sensor 18) and maps and programs stored in the memory 22. In the embodiment, a main process executed by the battery ECU 20 is a process for calculating an index indicating the amount of electrolyte reduction in each of the multiple batteries 12 included in the battery 11 (hereinafter also referred to as an "estimation process"). The estimation process by the battery ECU 20 will be described in detail later.

[0037] The PCU 30 includes, for example, an inverter and a converter (neither of which are shown). The PCU 30 performs bidirectional power conversion between the battery pack 10 (battery 11) and the motor generator 40 in accordance with a control signal from the ECU 80.

[0038] The motor generator 40 is, for example, a three-phase AC rotating electric machine with a permanent magnet embedded in a rotor (not shown). The rotor of the motor generator 40 is mechanically connected to drive wheels 55 via a power transmission gear 50. The motor generator 40 is driven using power supplied from the battery 11. The motor generator 40 is also capable of generating power by regenerative braking. The AC power generated by the motor generator 40 is converted to DC power by the PCU 30 and charged into the battery 11.

[0039] The inlet 60 is configured to be able to connect to a connector provided at the tip of a charging cable electrically connected to an external power source (e.g., a charging stand, etc.) (neither is shown). Power supplied from the external power source to the inlet 60 is supplied to the battery pack 10 (battery 11) via the power lines PL2, NL2 and the power lines PL1, NL1. The power lines PL2, NL2 are provided with a charging relay (not shown).

[0040] The notification device 70 includes at least one of a display device and an audio output device. The notification device 70 causes the display device to display information and causes the audio output device to output audio (for example, read out information) in accordance with a command from the ECU 80. For example, a navigation device may be configured to have the function of the notification device 70.

[0041] The ECU 80 includes a processor 81 such as a CPU, a memory 82 such as a ROM and a RAM, and an input / output port (not shown) for inputting and outputting various signals. The ECU 80 controls the devices so that the vehicle 1 is in a desired state based on input of signals from each sensor provided in the vehicle 1 and maps and programs stored in the memory 82. The ECU 80 controls the charging and discharging of the battery 11, for example, by controlling the PCU 30.

[0042] Here, it is known that in a secondary battery, the electrolyte is consumed during use (energization) and storage. When the amount of electrolyte decreases and becomes insufficient, there are areas where the electrodes and the electrolyte are not interposed, which may make it difficult for a chemical reaction to occur. This may result in a decrease in battery capacity and an increase in internal resistance. Therefore, it is necessary to monitor the decrease in the amount of electrolyte.

[0043] Therefore, in vehicle 1 according to this embodiment, battery ECU 20 executes estimation processing to calculate an index Easum indicating the amount of decrease in the electrolyte of each battery 12. Specifically, battery ECU 20 acquires the voltage Vb, current Ib, and temperature Tb of each battery 12 (hereinafter collectively referred to as "detection data") for each battery 12 at predetermined intervals (for example, control intervals), and calculates index Easum for each battery 12 based on these. Then, based on the index Easum, battery ECU 20 outputs a command to ECU 80 to limit the upper limit voltage of battery 11, outputs a command to ECU 80 to limit the input / output power of battery 11, and outputs a command to ECU 80 to issue a warning.

[0044] The memory 22 of the battery ECU 20 stores in advance a first map for calculating an index Ea1 indicating the amount of electrolyte reduction per unit time of the battery 12 when the battery 11 is energized, and a second map for calculating an index Ea2 indicating the amount of electrolyte reduction per unit time of the battery 12 when the battery 11 is stored. The first map and the second map can be created in advance based on experimental results. The unit time is the above-mentioned predetermined period (for example, a control period). The first map corresponds to an example of the "first information" according to the present disclosure. The second map corresponds to an example of the "second information" according to the present disclosure. The index Easum corresponds to an example of the "first index" according to the present disclosure. The index Ea1 corresponds to an example of the "second index" according to the present disclosure. The index Ea2 corresponds to an example of the "third index" according to the present disclosure.

[0045] Fig. 3 is a diagram for explaining a method for creating the first map. The horizontal axis of Fig. 3 indicates the number of times the cycle test was performed (number of cycles), and the vertical axis indicates the cycle retention rate (capacity retention rate) and the resistance increase rate. Graph G1 is a graph showing the relationship between the number of cycles and the cycle retention rate. Graph G2 is a graph showing the relationship between the number of cycles and the resistance increase rate.

[0046] The inventors performed a current cycle test for each temperature within the guaranteed temperature range of the battery 12. In the cycle test, a charge / discharge cycle was repeatedly performed at a lower limit voltage Vx, an upper limit voltage Vy (>Vx), and a predetermined current rate (for example, 1C or less). By setting a current rate of 1C or less at which heat generation due to charging / discharging can be ignored, experimental results for a desired temperature can be obtained. In the cycle test, the inventors disassembled the battery midway through the cycle while monitoring the capacity maintenance rate and the rate of increase in internal resistance, and investigated the remaining amount of electrolyte. As experimental results of the cycle test at a certain temperature, experimental results including graphs G1 and G2 shown in FIG. 3 were obtained.

[0047] As shown in the graph G2, it was found that the relationship between the number of cycles and the resistance increase rate has an inflection point P at which the resistance increase rate increases sharply. The inventors have found that the amount of electrolyte becomes zero at the inflection point P. Using this experimental result, the amount of electrolyte reduction per unit time for a voltage and temperature pair can be mapped based on the number of cycles until the inflection point P of the graph G2 is reached. For example, if the experimental result of FIG. 3 is from a cycle test at a certain temperature Ta, the map shows the amount of electrolyte reduction per unit time for each pair of voltages Vx to Vy and temperature Ta. The amount of electrolyte reduction per unit time for each pair of voltages Vx to Vy and temperature Ta may be set to the same value for each pair, or may be set to a larger value for a pair including a higher voltage, in consideration of the fact that the higher the voltage, the greater the consumption of electrolyte.

[0048] By conducting the same experiment as above for temperatures other than temperature Ta (temperatures within the guaranteed temperature range), it is possible to map the amount of electrolyte reduction per unit time for each temperature and voltage Vx to Vy. Using these, a first map is created. In other words, if the guaranteed temperatures of battery 12 are temperatures Tx to Ty, the first map shows the amount of electrolyte reduction per unit time for each pair of voltages Vy to Vx and temperatures Tx to Ty during current flow.

[0049] 4 is a diagram showing an example of the first map. The first map shows a tendency that the higher the temperature and the higher the voltage, the greater the reduction in the amount of electrolyte.

[0050] The inventors also conducted storage tests of the battery 12 at different temperatures and voltages within the guaranteed temperature range. In the storage tests, a specific temperature and a specific voltage were maintained, and the capacity retention rate and the rate of increase in internal resistance were monitored in the same manner as in the cycle test, while the battery was disassembled midway through the test to investigate the remaining amount of electrolyte. In the same manner as in the creation of the first map, a second map can be created based on the experimental results of the storage test. The second map shows the amount of electrolyte reduction per unit time for each set of voltages Vy-Vx and temperatures Tx-Ty during storage.

[0051] The battery ECU 20 acquires the voltage Vb and the temperature Tb at every predetermined period (for example, a control period), and calculates the index Ea1 or the index Ea2 by consulting the first map or the second map using the voltage Vb and the temperature Tb as arguments. For example, if the currently acquired voltage Vb and temperature Tb are those when the battery 11 is energized, the battery ECU 20 calculates the index Ea1 by consulting the first map using the voltage Vb and the temperature Tb as arguments. For example, if the currently acquired voltage Vb and temperature Tb are those when the battery 11 is stored, the battery ECU 20 calculates the index Ea2 by consulting the second map using the voltage Vb and the temperature Tb as arguments. Then, the battery ECU 20 adds the currently calculated index Ea1 or index Ea2 to the index Easum to update the index Easum. By updating and monitoring the index Easum, it is possible to monitor the amount of reduction in the electrolyte of each battery 12. Then, the battery ECU 20 outputs to the ECU 80 a command to limit the upper limit voltage of the battery 11, a command to limit the input / output power of the battery 11, or a command to issue a warning, depending on the index Easum. Hereinafter, a detailed description will be given with reference to FIG.

[0052] 5 is a flowchart showing the estimation process. This flowchart starts when the battery ECU 20 is started, and is repeatedly executed for each control period. Each step is realized by software processing by the battery ECU 20, but may also be realized by hardware (electrical circuitry) created within the battery ECU 20. Hereinafter, steps are abbreviated as "S".

[0053] In S1, the battery ECU 20 acquires the voltage Vb, current Ib, and temperature Tb of each battery 12 from the voltage monitoring module 16, current sensor 17, and temperature sensor 18, respectively (acquires detected data).

[0054] In S2, the battery ECU 20 judges whether the detection data (multiple voltages Vb, current Ib, multiple temperatures Tb) acquired in S1 are from when the battery 11 was energized (discharging or charging) or from when the battery 11 was stored. Specifically, the battery ECU 20 judges the state of the battery 11 (energized or stored) based on the current Ib acquired in S1. If the current Ib is not zero (NO in S2), the battery ECU 20 judges that the battery 11 is energized (i.e., the detection data acquired in S1 is from when the battery 11 was energized) and proceeds to S3. On the other hand, if the current Ib is zero (YES in S2), the battery ECU 20 judges that the battery is being stored (i.e., the detection data acquired in S1 is from when the battery 11 was stored) and proceeds to S4.

[0055] In S3, the battery ECU 20 reads out the first map from the memory 22. Then, the battery ECU 20 refers to the first map using the voltage Vb and temperature Tb acquired in S1 as arguments for each battery 12, and calculates an index Ea1 indicating the amount of reduction in the electrolyte in the current control cycle (unit time). After that, the battery ECU 20 advances the process to S5.

[0056] In S4, the battery ECU 20 reads the second map from the memory 22. Then, for each battery 12, the battery ECU 20 queries the second map with the voltage Vb and temperature Tb acquired in S1 as arguments, and calculates an index Ea2 indicating the amount of decrease in the electrolyte during the current control cycle (unit time). After that, the battery ECU 20 proceeds to S5 with the process.

[0057] In S5, the battery ECU 20 reads from the memory 22 an index Easum which is the cumulative total of the index Ea1 during energization and the index Ea2 during storage for each battery 12. For each battery 12, the battery ECU 20 adds the index Ea1 calculated in S3 or the index Ea2 calculated in S4 as the current amount (the amount of decrease in the electrolyte during the current unit time) to the index Easum. The index Easum is prepared for each battery 12.

[0058] In the following S6, 8, and 10, the battery ECU 20 compares the index Easum with each threshold value for each battery 12. In the memory 22 of the battery ECU 20, a first threshold value Tth1, a second threshold value Tth2 (<Tth1), and a third threshold value Tth3 (<Tth2) are stored. The respective values are set such that they become smaller in the order of the first threshold value Tth1, the second threshold value Tth2, and the third threshold value Tth3. The first threshold value Tth1 is a threshold value for determining whether to give a warning to the user of the vehicle 1. The first threshold value Tth1 can be set, for example, to a value with a certain margin from the value indicating that the electrolyte amount of the battery 12 is zero. The second threshold value Tth2 is a threshold value for determining whether to limit the input / output power of the battery 11. The second threshold value Tth2 can be set to a value with a further margin from the first threshold value Tth1. The third threshold value Tth3 is a threshold value for determining whether to limit the upper voltage of the battery 11. The third threshold value Tth3 can be set to a value with a further margin from the second threshold value Tth2. The magnitude of the margin for each threshold value can be appropriately set based on the specifications of the battery 11 (battery 12) and the like.

[0059] In S6, the battery ECU 20 reads out the first threshold value Tth1 from the memory 22 and compares the index Easum of each battery 12 with the first threshold value Tth1. If at least one of the indexes Easum of each battery 12 is greater than the first threshold value Tth1 (YES in S6), the battery ECU 20 proceeds to S7. If all of the indexes Easum of each battery 12 are equal to or less than the first threshold value Tth1 (NO in S6), the battery ECU 20 proceeds to S8.

[0060] In S7, the battery ECU 20 outputs a command to the ECU 80 to issue a warning. As a result, the ECU 80 controls the notification device 70 to issue a warning. The content of the warning may be, for example, a warning encouraging the user to have the battery 11 inspected, a warning encouraging the user to replace the battery 11, or the like. The notification device 70 may issue a warning by displaying a warning on a display device, by outputting a sound from a sound output device, or by both a warning by a display device and a warning by a sound output device.

[0061] In S8, the battery ECU 20 reads out the second threshold value Tth2 from the memory 22 and compares the index Easum of each battery 12 with the second threshold value Tth2. If at least one of the indexes Easum of each battery 12 is greater than the second threshold value Tth2 (YES in S8), the battery ECU 20 proceeds to S9. If all of the indexes Easum of each battery 12 are equal to or less than the second threshold value Tth2 (NO in S8), the battery ECU 20 proceeds to S10.

[0062] In S9, the battery ECU 20 outputs a command to the ECU 80 to limit the input / output power of the battery 11. As a result, the ECU 80 determines to limit the input / output power of the battery 11 to a preset input / output limit value. Therefore, from this point on, the input / output power of the battery 11 is limited.

[0063] In S10, the battery ECU 20 reads out the third threshold value Tth3 from the memory 22, and compares the index Easum of each battery 12 with the third threshold value Tth3. If at least one of the indexes Easum of each battery 12 is greater than the third threshold value Tth3 (YES in S10), the battery ECU 20 advances the process to S11. If all of the indexes Easum of each battery 12 are equal to or less than the third threshold value Tth3 (NO in S10), the battery ECU 20 advances the process to RETURN.

[0064] In S11, the battery ECU 20 outputs a command to the ECU 80 to limit the upper limit voltage of the battery 11. As a result, the ECU 80 determines to limit the upper limit voltage of the battery 11 to a preset upper limit value. Therefore, from this point on, the upper limit voltage of the battery 11 is limited.

[0065] As described above, in this embodiment, the first map for calculating the index Ea1 indicating the amount of decrease in the electrolyte of the battery 12 per unit time when the battery 11 is energized, and the second map for calculating the index Ea2 indicating the amount of decrease in the electrolyte of the battery 12 per unit time when the battery 11 is stored are created in advance by experimentation and stored in the memory 22 of the battery ECU 20. The battery ECU 20 acquires the voltage Vb, the current Ib, and the temperature Tb of each battery 12 from the voltage monitoring module 16, the current sensor 17, and the temperature sensor 18 for each unit time (acquires detection data). The battery ECU 20 determines whether the acquired detection data is from when the battery 11 is energized or when it is stored, based on the current Ib. If the detection data is from when the battery 11 is energized, the battery ECU 20 calculates the index Ea1 for each battery 12 based on the first map, using the voltage Vb and the temperature Tb as arguments. If the detection data is from the time of storage, the battery ECU 20 calculates the index Ea2 for each battery 12 based on the second map using the voltage Vb and temperature Tb as arguments. The battery ECU 20 adds the currently calculated index Ea1 or index Ea2 to the index Easum to update the index Easum. By calculating the index Ea1 or index Ea2 for each unit time and updating the index Easum, it is possible to monitor the amount of electrolyte reduction in each battery 12. Since the amount of electrolyte reduction can be estimated using the detected voltage and temperature, it is possible to accurately estimate the amount of electrolyte reduction in the battery 12.

[0066] For example, a method is known for estimating the amount of electrolyte loss by detecting gas generated by decomposition of the electrolyte. However, in a battery having a large aspect ratio Ar (e.g., 1.5 or more) and a separator containing a binder having an adhesive function, gas is likely to remain in the electrode body. Therefore, it is not possible to accurately estimate the amount of electrolyte loss in the battery. With the above method according to the present embodiment, it is possible to accurately estimate the amount of electrolyte loss in the battery, even in a battery having a large aspect ratio Ar (e.g., 1.5 or more) and a separator containing a binder having an adhesive function.

[0067] Furthermore, when at least one of the indexes Easum of each battery 12 exceeds the first threshold value Tth1, the battery ECU 20 outputs a command to the ECU 80 to issue a warning. As a result, the ECU 80 controls the notification device 70 to issue a warning. Thus, a warning can be issued to the user of the vehicle 1. This allows the user to take appropriate measures regarding the battery 11.

[0068] Furthermore, when at least one of the indexes Easum of each battery 12 is less than the first threshold value Tth1 and exceeds the second threshold value Tth2, the battery ECU 20 outputs a command to the ECU 80 to limit the input / output power of the battery 11. As a result, the ECU 80 determines to limit the input / output power of the battery 11. Therefore, since the input / output power of the battery 11 is limited, the decrease in the electrolyte can be slowed down.

[0069] Furthermore, when at least one of the indexes Easum of each battery 12 is less than the second threshold value Tth2 and exceeds the third threshold value Tth3, the battery ECU 20 outputs a command to the ECU 80 to limit the upper limit voltage of the battery 11. As a result, the ECU 80 determines to limit the upper limit voltage of the battery 11. Since the upper limit voltage of the battery 11 is thus limited, the decrease in the electrolyte can be slowed down.

[0070] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0071] 1 vehicle, 10 battery pack, 11 battery, 12 battery, 13 system main relay device, 14, 15 SMR, 16 voltage monitoring module, 17 current sensor, 18 temperature sensor, 20 battery ECU, 21 processor, 22 memory, 30 PCU, 40 motor generator, 50 power transmission gear, 55 drive wheel, 60 inlet, 70 alarm device, 80 ECU, 81 processor, 82 memory, 121 housing, 122 cover, 123 positive terminal, 124 negative terminal, 125 electrode body, 126 positive electrode, 127 negative electrode, 128 separator.

Claims

1. a secondary battery having an electrolyte; a detection device for detecting a voltage and a temperature of the secondary battery; a storage device that stores first information indicating a relationship between a voltage of the secondary battery, a temperature of the secondary battery, and an amount of the electrolyte reduced when the secondary battery is energized, and second information indicating a relationship between a voltage of the secondary battery, a temperature of the secondary battery, and an amount of the electrolyte reduced when the secondary battery is stored; A control device that calculates a first index indicating a reduction amount of the electrolyte, the first index includes a second index indicating an amount of the electrolyte reduced due to energization of the secondary battery, and a third index indicating an amount of the electrolyte reduced due to storage of the secondary battery, The control device includes: When the secondary battery is energized, the second index is calculated based on the voltage and temperature detected by the detection device and the first information; The power supply device calculates the third index based on the voltage and temperature detected by the detection device and the second information during storage of the secondary battery.

2. the first information is created based on a result of a cycle test of the secondary battery performed for each temperature; 2. The power supply device according to claim 1, wherein the second information is created based on the results of a storage test of the secondary battery carried out for each temperature and voltage.

3. The power supply device according to claim 2 , wherein the control device outputs a command to issue a warning when the first indicator is equal to or greater than a first threshold value.

4. 4. The power supply device according to claim 3, wherein the control device outputs a command to limit input / output power of the secondary battery when the first indicator is less than the first threshold and is equal to or greater than a second threshold that is smaller than the first threshold.

5. 5. The power supply device according to claim 4, wherein the control device outputs a command to limit an upper limit voltage value of the secondary battery when the first indicator is less than the second threshold and is equal to or greater than a third threshold that is smaller than the second threshold.

6. The secondary battery includes an electrode assembly having an aspect ratio of 1.5 or more, the electrode body is configured by laminating a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, The power supply device according to claim 1 , wherein the separator includes a functional layer having a function of bonding the positive electrode and the negative electrode to the separator.

Images