Battery system

Abstract

To estimate an estimated temperature of a terminal without directly providing a temperature sensor to the terminal.SOLUTION: A battery system 1 includes a battery cell 20, a temperature sensor 94, a current sensor 92 and a control unit 100. The battery cell 20 includes a case 30 and a terminal 50 provided on the case 30. The temperature sensor 94 measures a surface temperature T.cell of the case 30. The current sensor 92 measures a charge / discharge current flowing through the terminal 50. The control unit 100 includes: a measurement part 103 for measuring the surface temperature T,cell of the case 30 by the temperature sensor 94; a calculation part 105 for calculating an estimated temperature rise ΔT.gas (n) based on an amount of heat generated by the charge / discharge current flowing through the terminal 50; and an estimation part 107 for estimating an estimated temperature T.gas of the terminal 50 based on the surface temperature T.cell of the case 30 and the estimated temperature rise ΔT.gas (n).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a battery system. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open Publication No. 2020-35531 discloses a battery temperature estimation device that estimates the temperature distribution within a cell of a secondary battery. This battery temperature estimation device includes a first estimation unit, a second estimation unit, and a third estimation unit. The first estimation unit divides the internal structure of the cell into multiple parts and estimates the current distribution in each part within the cell using a predetermined circuit network model.

[0003] The second estimation unit estimates the heat generation distribution of each part in the cell using the current distribution and the resistance elements in each part in the cell. The third estimation unit estimates the temperature distribution of each part in the cell by calculating the temperature change in each part in the cell using the heat generation distribution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-35531 Summary of the Invention [Problem to be solved by the invention]

[0005] When estimating the temperature distribution within a cell of a secondary battery, for example, the temperature of a component of the cell near where the current flows may be higher than the temperature of other components (e.g., the cell body). This is thought to be because, for example, if the component near where the current flows has a small heat capacity against heat generated by current flow or a component with poor thermal diffusion, its temperature is more likely to rise than the surface temperature of a cell with a large heat capacity. However, if the component near where the current flows is relatively small, it is difficult to directly install a temperature sensor, making it difficult to measure the temperature of the component near where the current flows. [Means for solving the problem]

[0006] The battery system disclosed herein includes a battery cell, a temperature sensor, a current sensor, and a control device. The battery cell includes a case and terminals provided on the case. The temperature sensor is configured to measure the surface temperature of the case. The current sensor is configured to measure charge / discharge current flowing through the terminals. The control device includes a measurement unit that measures the surface temperature of the case using the temperature sensor, a calculation unit that calculates an estimated temperature rise based on the amount of heat generated by the charge / discharge current flowing through the terminals, and an estimation unit that estimates the estimated temperature of the terminals based on the surface temperature of the case and the estimated temperature rise.

[0007] The battery system disclosed herein can estimate the terminal temperatures based on the surface temperature of the case and the estimated temperature rise, thereby enabling estimation of the terminal temperatures without directly installing temperature sensors on the terminals. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a battery system. [Figure 2] FIG. 2 is a vertical cross-sectional view that schematically shows the internal structure of a battery cell. [Figure 3] FIG. 3 is a perspective view that schematically shows an electrode body of a battery cell. [Figure 4] FIG. 4 is a block diagram of the battery system. [Figure 5] FIG. 5 is a flowchart showing a procedure for estimating the temperature of the terminal gasket. [Figure 6] FIG. 6 is a flowchart showing the procedure for adjusting the charge / discharge current flowing through the battery cell. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, one embodiment of the technology disclosed herein will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any way. Each drawing is a schematic diagram and does not necessarily faithfully reflect an actual product. Furthermore, the same reference numerals are appropriately used for components and parts that perform the same function, and redundant explanations will be omitted where appropriate.

[0010] FIG. 1 is a schematic diagram showing a battery system 1 according to this embodiment. As shown in FIG. 1, the battery system 1 is connected to a load 5. The load 5 is not particularly limited, but may be, for example, a drive device such as an electric motor of a vehicle, or an inverter. A smoothing capacitor for reducing sudden changes in current may be connected to the load 5. Here, the battery system 1 is mounted on a vehicle such as a hybrid vehicle, a plug-in hybrid vehicle, or an electric vehicle, and is used as a power source that supplies power to an electric motor that drives the vehicle. However, the battery system 1 is not limited to use in a vehicle.

[0011] 1, the battery system 1 includes a pair of output terminals 8, a battery unit 10, a first contactor 81, and a second contactor 82. The pair of output terminals 8 is connected to a load 5. Here, the pair of output terminals 8 includes a positive output terminal 8a and a negative output terminal 8b.

[0012] The battery unit 10 is connected to a pair of output terminals 8 and is indirectly connected to a load 5 via the pair of output terminals 8. The load 5 can convert the electric power of the battery unit 10 into motive power or supply regenerated electric power to the battery unit 10.

[0013] In this embodiment, as shown in FIG. 1, the battery unit 10 has a plurality of battery cells 20. The battery cells 20 are chargeable and dischargeable. For example, a secondary battery that can be repeatedly charged and discharged by the movement of charge carriers between a pair of electrodes (e.g., a positive electrode and a negative electrode) via an electrolyte may be used as the battery cell 20. For example, a lithium ion secondary battery or a nickel-metal hydride battery may be used as the battery cell 20. Here, the battery cell 20 is a lithium ion secondary battery. The plurality of battery cells 20 are connected in series. Here, the plurality of battery cells 20 are connected in series via a bus bar (not shown). The number of battery cells 20 constituting the battery unit 10 is not particularly limited and is a predetermined number. The detailed configuration of the battery cells 20 will be described later.

[0014] As shown in FIG. 1, the first contactor 81 is connected in series to the battery unit 10 (in other words, a plurality of battery cells 20 connected in series). Here, the first contactor 81 is connected to the positive electrode end of the battery unit 10. The first contactor 81 is provided between the battery unit 10 and the positive electrode output terminal 8a. The first contactor 81 switches the connection between the positive electrode end of the battery unit 10 and the load 5 between ON and OFF. Here, the contactor is, in other words, a relay.

[0015] Like the first contactor 81, the second contactor 82 is connected in series to the battery unit 10 (in other words, the plurality of battery cells 20 connected in series). Here, the second contactor 82 is connected to the negative electrode end of the battery unit 10. The second contactor 82 is provided between the battery unit 10 and the negative electrode output terminal 8b. The second contactor 82 switches the connection between the negative electrode end of the battery unit 10 and the load 5 between ON and OFF. Note that in this embodiment, turning the contactor ON refers to a connected state (closed state). Turning the contactor OFF refers to a disconnected state (open state). In this embodiment, the first contactor 81 and the second contactor 82 are electrically switched ON and OFF.

[0016] Next, the configuration of the battery cell 20 will be described. In this embodiment, the multiple battery cells 20 have the same configuration. FIG. 2 is a vertical cross-sectional view that schematically shows the internal structure of the battery cell 20. FIG. 3 is a perspective view that schematically shows the electrode body 40 of the battery cell 20. FIG. 3 shows a state in which a portion of the electrode body 40 is unfolded. As shown in FIG. 2, the battery cell 20 includes a case 30, the electrode body 40, an electrolyte (not shown), and terminals 50.

[0017] The case 30 accommodates the electrode assembly 40 and the electrolyte. The case 30 is box-shaped. Here, the case 30 has an outer shape of a flat, bottomed rectangular parallelepiped (in other words, square). However, the shape of the case 30 is not particularly limited. Furthermore, the material from which the case 30 is formed is not particularly limited. The case 30 is made of, for example, metal. Examples of materials from which the case 30 is formed include aluminum, aluminum alloy, iron, and iron alloy. In this embodiment, as shown in FIG. 2 , the case 30 has an exterior body 32 and a sealing plate 34. It is preferable that the case 30 be square and include the exterior body 32 and the sealing plate 34.

[0018] The exterior body 32 is a flat, rectangular container with a bottom. Here, an opening 33 is formed at the upper end of the exterior body 32. The exterior body 32 opens upward. The sealing plate 34 is attached to the exterior body 32. The sealing plate 34 closes the opening 33 of the exterior body 32. In this embodiment, the sealing plate 34 is plate-shaped and has a substantially rectangular shape in a plan view. The periphery of the sealing plate 34 is joined (e.g., welded) to the opening 33 of the exterior body 32. This hermetically seals (e.g., seals) the case 30.

[0019] The sealing plate 34 is provided with a liquid inlet 35, a gas release valve 37, and two terminal insertion holes 38 and 39. The liquid inlet 35 is a through-hole for injecting the electrolyte into the inside of the case 30 after the sealing plate 34 is assembled to the exterior body 32. The liquid inlet 35 is sealed with a sealing member 36 after the electrolyte is injected. The gas release valve 37 is a thin-walled portion designed to rupture (for example, open) when the pressure inside the case 30 reaches or exceeds a predetermined value, thereby releasing gas inside the case 30 to the outside. The terminal insertion holes 38 and 39 are through-holes formed at both ends in the length direction of the sealing plate 34 and penetrating vertically.

[0020] The electrolyte solution housed in the case 30 may be the same as conventional ones and is not particularly limited. The electrolyte solution is, for example, a non-aqueous electrolyte solution containing a non-aqueous solvent (organic solvent) and a supporting salt (electrolyte salt). The electrolyte solution is preferably a non-aqueous electrolyte solution. Examples of non-aqueous solvents include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as lithium hexafluorophosphate (LiPF6). The electrolyte solution may contain additives as needed.

[0021] The electrode assembly 40 is a power-generating element of the battery cell 20. As shown in FIG. 3, the electrode assembly 40 includes a positive electrode sheet 41, a negative electrode sheet 42, and a separator 43. In this embodiment, the electrode assembly 40 is a wound electrode assembly. The wound electrode assembly is produced by stacking and winding the positive electrode sheet 41, the negative electrode sheet 42, and the separator 43. However, the structure of the electrode assembly 40 is not particularly limited, and may have another conventionally known structure (for example, a stacked electrode assembly).

[0022] The positive electrode sheet 41 has a positive electrode core 41a, which is a conductive metal foil, and a positive electrode active material layer 41b formed on the surface of the positive electrode core 41a. The positive electrode core 41a is made of aluminum or the like. The positive electrode active material layer 41b contains a positive electrode active material, a conductive material, a binder, and the like. The positive electrode active material may be, for example, a lithium composite metal oxide having a layered structure or a spinel structure (for example, LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2, LiNiO2, LiCoO2, LiFeO2, LiMn2O4, LiNi 0.5 Mn 1.5 Examples of the conductive material include carbon materials such as acetylene black and graphite. The binder may be a resin material such as polyvinylidene fluoride (PVdF). In this embodiment, a positive electrode tab 41c protrudes from one end of the positive electrode sheet 41 in the width direction (the left-right direction on the paper surface of FIG. 3). A plurality of positive electrode tabs 41c are provided at predetermined intervals in the length direction of the positive electrode sheet 41. The positive electrode tab 41c is a portion where the positive electrode active material layer 41b is not formed and where the positive electrode core 41a is exposed. The plurality of positive electrode tabs 41c are configured to overlap when the electrode body 40 is wound.

[0023] The negative electrode sheet 42 includes a negative electrode core 42a, which is a conductive metal foil, and a negative electrode active material layer 42b formed on the surface of the negative electrode core 42a. The negative electrode core 42a is made of copper or the like. The negative electrode active material layer 42b includes a negative electrode active material, a binder, a thickener, and the like. Examples of the negative electrode active material include carbon materials such as graphite, hard carbon, and soft carbon. The negative electrode active material may include a silicon-containing material. Examples of the binder include resin materials such as styrene butadiene rubber (SBR). Examples of the thickener include resin materials such as carboxymethyl cellulose (CMC). In this embodiment, a negative electrode tab 42c protrudes from the other end of the negative electrode sheet 42 in the width direction. A plurality of negative electrode tabs 42c are provided at predetermined intervals along the length of the negative electrode sheet 42. The negative electrode tab 42c is a portion where the negative electrode active material layer 42b is not formed and where the negative electrode core 42a is exposed. When the electrode body 40 is wound, the negative electrode tabs 42c are configured to overlap each other.

[0024] The separator 43 is an insulating sheet interposed between the positive electrode sheet 41 and the negative electrode sheet 42. Resin materials such as polyethylene (PE), polypropylene (PP), polyester, cellulose, and polyamide can be used for the separator 43. A heat-resistant layer containing an inorganic filler may be formed on the surface of the separator 43. Examples of inorganic fillers that can be used include inorganic oxides such as aluminum oxide, magnesium oxide, silicon oxide, and titanium oxide; nitrides such as aluminum nitride and silicon nitride; metal hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; and clay minerals such as mica, talc, boehmite, zeolite, apatite, and kaolin. The separator 43 may contain a binder for fixing the heat-resistant layer to the surface. Examples of binders that can be used include resin binders such as polyvinylidene fluoride (PVdF) and acrylic resins.

[0025] As shown in FIG. 2 , the terminal 50 is provided on the case 30. Here, the terminal 50 is provided on the sealing plate 34 of the case 30. In this embodiment, the terminal 50 has a positive electrode terminal 51 and a negative electrode terminal 52. The positive electrode terminal 51 is inserted into and fixed in a terminal insertion hole 38 formed in the sealing plate 34. The negative electrode terminal 52 is inserted into and fixed in a terminal insertion hole 39 formed in the sealing plate 34. In this embodiment, the positive electrode terminal 51 and the negative electrode terminal 52 have corresponding configurations. In the following description, the term “terminal 50” is used when describing both the positive electrode terminal 51 and the negative electrode terminal 52.

[0026] In this embodiment, as shown in FIG. 2 , the terminal 50 has a terminal body 61 and a gasket 62. The terminal body 61 is a portion through which charge / discharge current flows. The terminal body 61 is connected to the electrode assembly 40 inside the case 30. The terminal body 61 of the positive terminal 51 is inserted through the terminal insertion hole 38 and extends from the inside to the outside of the sealing plate 34. The terminal body 61 of the negative terminal 52 is inserted through the terminal insertion hole 39 and extends from the inside to the outside of the sealing plate 34. Here, in the positive terminal 51, a plate-shaped positive electrode external conductive member 65a is connected to the external surface of the terminal body 61. In the negative terminal 52, a plate-shaped negative electrode external conductive member 66a is connected to the external surface of the terminal body 61. The positive electrode external conductive member 65a is connected to other battery cells 20 and the first contactor 81 (see FIG. 1 ) via an external connection member such as a bus bar. The negative electrode external conductive member 66a is connected to other battery cells 20 and the second contactor 82 (see FIG. 1) via an external connection member.

[0027] In the positive electrode terminal 51, the inside of the terminal body 61 is connected to a positive electrode current collector 65b. The positive electrode current collector 65b is connected to the positive electrode sheet 41 (see FIG. 3) of the electrode assembly 40. The terminal body 61 of the positive electrode terminal 51 is connected to the positive electrode sheet 41 (more specifically, to a plurality of positive electrode tabs 41c) via the positive electrode current collector 65b. In the negative electrode terminal 52, the inside of the terminal body 61 is connected to a negative electrode current collector 66b. The negative electrode current collector 66b is connected to the negative electrode sheet 42 (see FIG. 3) of the electrode assembly 40. The terminal body 61 of the negative electrode terminal 52 is connected to the negative electrode sheet 42 (more specifically, to a plurality of negative electrode tabs 42c) via the negative electrode current collector 66b.

[0028] The gasket 62 insulates the terminal body 61 from the case 30. Here, the gasket 62 insulates the part that performs electrical input and output (here, the terminal body 61) from the sealing plate 34. In this embodiment, the gasket 62 is attached to the terminal insertion holes 38, 39 formed in the sealing plate 34. The gasket 62 is provided between the terminal body 61 and the sealing plate 34. In this embodiment, if the gasket 62 does not have a sufficient sealing ability for the terminal insertion holes 38, 39, vaporized electrolyte may leak to the outside of the case 30, degrading the charge / discharge characteristics of the battery cell 20. Therefore, the gasket 62 functions to seal the terminal insertion holes 38, 39 so that the electrolyte contained in the case 30 does not leak from the terminal insertion holes 38, 39 to the outside of the case 30. Here, in the positive electrode terminal 51, the gasket 62 extends from the terminal insertion hole 38 between the sealing plate 34 and the terminal body 61 and between the sealing plate 34 and the positive electrode external conductive member 65a. In the negative electrode terminal 52, the gasket 62 extends from the terminal insertion hole 39 between the sealing plate 34 and the terminal body 61 and between the sealing plate 34 and the negative electrode external conductive member 66a. The material forming the gasket 62 is not particularly limited as long as it insulates the terminal body 61 from the case 30. Here, the gasket 62 is formed of an insulating material, such as a resin. Examples of resins that form the gasket 62 include fluororesin (PFA) and polyphenylene sulfide (PPS). In this embodiment, the gasket 62 is a material that can come into direct contact with the electrolyte. Therefore, the gasket 62 is preferably formed of a material that is chemically resistant to the electrolyte.

[0029] In this embodiment, as shown in FIG. 1 , the battery system 1 includes a current sensor 92, a temperature sensor 94, and a control device 100. The current sensor 92 measures the charge / discharge current flowing through the terminal 50 of the battery cell 20. The current sensor 92 measures the charge / discharge current flowing through the terminal body 61 of the terminal 50. The current sensor 92 may measure the charge / discharge current flowing through the positive terminal 51 or the negative terminal 52. In this embodiment, as described above, the multiple battery cells 20 constituting the battery unit 10 are connected in series. Therefore, the charge / discharge current flowing through the battery unit 10 and the charge / discharge current flowing through each battery cell 20 are the same value. Therefore, the current sensor 92 may measure the charge / discharge current flowing through one of the multiple battery cells 20, or may measure the charge / discharge current flowing through the entire battery unit 10. In this embodiment, the current sensor 92 is provided between the battery unit 10 and the second contactor 82, and is configured to measure the charge / discharge current on the negative electrode side of the battery unit 10.

[0030] As shown in FIG. 2, the temperature sensor 94 is configured to measure the surface temperature of the case 30 of the battery cell 20. Here, the temperature sensor 94 is provided on the sealing plate 34 of the case 30 (e.g., the upper surface of the sealing plate 34) and measures the surface temperature of the sealing plate 34. The position of the temperature sensor 94 relative to the sealing plate 34 is not particularly limited. For example, the temperature sensor 94 is provided on the upper surface of the central portion of the sealing plate 34, at a location on the sealing plate 34 other than the gas release valve 37. The temperature sensor 94 is preferably provided as close as possible to the gasket 62. For example, the temperature sensor 94 may be provided closer to the gasket 62, the temperature of which is to be estimated, than the gas release valve 37. Alternatively, the temperature sensor 94 may be provided closer to the gasket 62, the temperature of which is to be estimated, than the liquid injection hole 35. The temperature sensor 94 is, for example, a thermistor. In this embodiment, as shown in FIG. 1, one temperature sensor 94 is provided for each battery cell 20. Therefore, the number of temperature sensors 94 is the same as the number of battery cells 20 constituting the battery unit 10. However, if the surface temperatures of the battery cells 20 (here, the surface temperatures of the case 30) are substantially equal (for example, the temperature difference is equal to or less than a predetermined threshold), it is not necessary to measure the surface temperatures of all of the battery cells 20, and the number of temperature sensors 94 may be fewer than the number of battery cells 20. Furthermore, for example, depending on how the battery unit 10 is used, including external environmental factors at the installation location, it is possible that the battery cell 20 that becomes hotter among the multiple battery cells 20 may change. In this case, the temperature sensor 94 may be provided to measure the surface temperatures of the multiple battery cells 20 that may become hotter depending on the external environmental factors. Furthermore, in this case, even if the battery cell 20 that becomes hotter varies depending on the external environmental factors, the temperature sensor 94 may be configured to estimate the surface temperature of the hotter battery cell 20 by correcting the surface temperature based on the surface temperature of the separately measured battery cell 20.

[0031] The control device 100 controls the charging and discharging of the battery unit 10. The control device 100 also performs control to estimate the temperature of the gasket 62 of the terminal 50 based on the surface temperature of the case 30 of the battery cell 20, and also performs control to limit the charging and discharging current flowing to the battery unit 10 based on the estimated temperature of the gasket 62. The configuration of the control device 100 is not particularly limited. The control device 100 is, for example, a microcomputer. The control device 100 includes, for example, an I / F, a CPU, a ROM, and a RAM. The control device 100 may be configured from a single computer or multiple computers.

[0032] Fig. 4 is a block diagram of the battery system 1. As shown in Fig. 4, the control device 100 is communicatively connected to a first contactor 81, a second contactor 82, a current sensor 92, and a temperature sensor 94. The control device 100 controls the ON / OFF switching of the first contactor 81 and the second contactor 82. The control device 100 acquires the value of the charge / discharge current flowing through the battery cell 20 from the current sensor 92. The control device 100 acquires the surface temperature of the case 30 from the temperature sensor 94. The control device 100 is also communicatively connected to a vehicle control device 200 that controls the entire vehicle in which the battery system 1 is installed.

[0033] 4, the control device 100 includes a storage unit 101, a measurement unit 103, a current measurement unit 104, a calculation unit 105, an estimation unit 107, a surface determination unit 109, a first determination unit 111, a current limiting unit 113, a second determination unit 115, and a prohibition unit 117. Each of the units 101 to 117 of the control device 100 may be realized by one or more processors or may be realized by a circuit. Specific features of each of the units 101 to 117 will be described later.

[0034] In this embodiment, in order to prevent the battery cell 20 from being overheated, the amount of heat generated can be reduced by controlling the charge / discharge current to the battery cell 20. This control to reduce the amount of heat generated can be performed, for example, based on the temperature of a component of the battery cell 20 that has low heat resistance. In this embodiment, the component with low heat resistance is, for example, a resin gasket 62 at the terminal 50, as shown in FIG. 2. For example, in order to measure the temperature of the gasket 62, it is conceivable to provide a temperature sensor 94 on the gasket 62. However, because the gasket 62 is a small component, it is difficult to directly provide the temperature sensor 94 on the gasket 62.

[0035] Therefore, in this embodiment, the surface temperature of the case 30 is measured, and the temperature of the gasket 62 is estimated from the surface temperature of the case 30. Next, the procedure for estimating the temperature of the gasket 62 of the terminal 50 in each battery cell 20 will be described with reference to the flowchart in FIG.

[0036] First, in step S101, the measurement unit 103 in FIG. 4 measures the surface temperature T.cell of the case 30. Here, the surface temperature T.cell of the case 30 refers to the surface temperature of the sealing plate 34. The measurement unit 103 measures (in other words, acquires) the surface temperature T.cell of the case 30 using the temperature sensor 94. For example, the measurement unit 103 acquires temperature information (here, the surface temperature T.cell of the case 30) from the temperature sensor 94 as an electrical signal. The measurement unit 103 converts the acquired electrical signal to acquire the surface temperature T.cell. The surface temperature T.cell of the case 30 measured by the measurement unit 103 is stored in the memory unit 101 in FIG. 4.

[0037] Next, in step S103 of FIG. 5 , the current measurement unit 104 of FIG. 4 measures the charge / discharge current flowing through the battery cell 20 (more specifically, the terminal body 61 of the terminal 50 (see FIG. 2 )). Here, the charge / discharge current flowing through the battery cell 20 refers to the charge / discharge current flowing through the battery unit 10. In this embodiment, the Irms value of the charge / discharge current refers to the effective value. The current measurement unit 104 measures the charge / discharge current flowing through the battery cell 20 using the current sensor 92. For example, the current measurement unit 104 transmits a current acquisition signal to the current sensor 92. Having received the current acquisition signal, the current sensor 92 measures the charge / discharge current flowing through the battery unit 10 as the charge / discharge current flowing through the battery cell 20. Thereafter, the current sensor 92 transmits the measured charge / discharge current of the battery cell 20 to the control device 100. The current measurement unit 104 acquires the charge / discharge current of the battery cell 20 transmitted from the current sensor 92. The charge / discharge current of the battery cell 20 measured by the current measurement unit 104 is stored in the storage unit 101 in Fig. 4. In this embodiment, the charge / discharge current measured by the current sensor 92 is an instantaneous value of the charge / discharge current. Here, the current sensor 92 measures the instantaneous value of the charge / discharge current, and the Irms value is calculated by the calculation unit 105 described below.

[0038] Next, in step S105 of FIG. 5, the calculation unit 105 of FIG. 4 calculates an estimated temperature rise ΔT.gas(n) in the gasket 62. The estimated temperature rise ΔT.gas(n) is a parameter used when calculating the estimated temperature T.gas of the gasket 62, and is a temperature rise based on the amount of heat generated by the Irms value due to the charge / discharge current. Here, the calculation unit 105 calculates the estimated temperature rise ΔT.gas(n) based on the amount of heat generated by the Irms value due to the charge / discharge current flowing through the terminal body 61 of the battery cell 20. Here, the calculation unit 105 calculates the Irms value from the instantaneous value of the charge / discharge current. Then, the calculation unit 105 calculates the estimated temperature rise ΔT.gas(n) from the Irms value of the battery cell 20. In this embodiment, the calculation unit 105 calculates the estimated temperature rise ΔT.gas(n) using a predetermined first-order lag formula based on the amount of heat generated by the Irms value due to the charge / discharge current. The calculation formula for this first-order lag system is not particularly limited, but is shown, for example, by the following formula (1). ΔT.gas(n)=(Ts / (Ts+Tc))×k×Irms 2 +(Tc / (Ts+Tc))×ΔT.gas(n-1) ···(1)

[0039] In the above formula (1), which is a calculation formula for a first-order lag system, Ts is the sampling period, Tc is the time constant, k is the thermal constant, Irms is the Irms value of the charge / discharge current, and ΔT.gas(n-1) is the estimated temperature rise of the gasket 62 from the previous time. In the above formula (1), k×Irms 2 indicates the amount of heat generated by the Irms value due to the charge / discharge current. The sampling period Ts, the time constant Tc, and the thermal constant k may be predetermined fixed values ​​or may be values ​​that are set appropriately. For example, the sampling period Ts may be determined by the design of the control device 100. The time constant Tc and the thermal constant k may be determined by actual measurements or simulations. The estimated temperature rise ΔT.gas(n) calculated by the calculation unit 105 in the above manner is stored in the memory unit 101 of FIG. 4.

[0040] Next, in step S107 of Fig. 5, the estimation unit 107 of Fig. 4 estimates the estimated temperature T.gas of the gasket 62. In this embodiment, the estimation unit 107 calculates the estimated temperature T.gas of the gasket 62 based on the surface temperature T.cell of the case 30 and the estimated temperature increase ΔT.gas(n). Here, the estimation unit 107 adds the surface temperature T.cell of the case 30 and the estimated temperature increase ΔT.gas(n), that is, estimates the estimated temperature T.gas of the gasket 62 by the following equation (2). T.gas=ΔT.gas(n)+T.cell ···(2)

[0041] The above describes the procedure for estimating the estimated temperature T.gas of the terminal 50 (specifically, the gasket 62) in the battery cell 20. Next, the procedure for adjusting the charge / discharge current flowing through the battery cell 20 using the estimated temperature T.gas of the gasket 62 will be described with reference to the flowchart in FIG.

[0042] Here, first, in step S201, measurement unit 103 in FIG. 4 measures surface temperature T.cell of case 30, similarly to step S101 in FIG.

[0043] Next, in step S203 of FIG. 6, the surface determination unit 109 of FIG. 4 determines whether the surface temperature T.cell of the case 30 is equal to or lower than a predetermined surface threshold value Th1. Here, the surface threshold value Th1 is a threshold value for determining whether the surface temperature T.cell of the case 30 is low. A specific value of the surface threshold value Th1 is, for example, an arbitrary value between 10°C and 30°C, such as 20°C. However, the surface threshold value Th1 is determined depending on the state of the battery cell 20 and the environment in which the battery cell 20 is used. The surface threshold value Th1 is pre-stored in the storage unit 101 of FIG. 4. If the surface determination unit 109 determines in step S203 that the surface temperature T.cell is equal to or lower than the surface threshold value Th1, it is assumed that the surface temperature T.cell of the case 30 is sufficiently low, and therefore the temperature of the gasket 62 is also sufficiently low, even if the highest current within the range assumed in the design of the battery cell 20 flows. If the temperature of the gasket 62 is estimated to be sufficiently low, it is determined that there is no need to limit the charge / discharge current. 6 and subsequent steps are not executed, and no control is performed by the current measurement unit 104, calculation unit 105, estimation unit 107, first determination unit 111, current limiting unit 113, second determination unit 115, and prohibition unit 117. Note that if there is a possibility that a current higher than that assumed in the design of the battery cell 20 will flow, the surface threshold value Th1 may be set low, or step S203 may be omitted.

[0044] On the other hand, if the surface determination unit 109 determines in step S203 of FIG. 6 that the surface temperature T.cell of the case 30 is higher than the surface threshold Th1, the process proceeds to step S205 of FIG. 6. In step S205, the current measurement unit 104 of FIG. 4 measures the charge / discharge current flowing through the battery cell 20 (more specifically, the terminal body 61 of the terminal 50 (see FIG. 2)), similar to step S103 of FIG. 5. Next, in step S207 of FIG. 6, the calculation unit 105 of FIG. 4 calculates the estimated temperature rise ΔT.gas(n) of the gasket 62 based on the amount of heat generated by the Irms value due to the charge / discharge current, similar to step S105 of FIG. 5. For example, the estimated temperature rise ΔT.gas(n) is calculated using a first-order lag equation such as equation (1) above. Next, in step S209 of FIG. 6, the estimation unit 107 of FIG. 4 estimates the estimated temperature T.gas of the gasket 62, similar to step S107 of FIG. 5. For example, the estimated temperature T.gas is calculated by adding the surface temperature T.cell of the case 30 and the estimated temperature rise ΔT.gas(n).

[0045] Next, in step S211 of FIG. 6, the first determination unit 111 of FIG. 4 determines whether the estimated temperature T.gas of the gasket 62 is equal to or higher than a predetermined first threshold value Th2. The first threshold value Th2 is a value used to determine whether the estimated temperature T.gas of the gasket 62 is too high. Here, the first threshold value Th2 is a value used to determine whether to limit the charge / discharge current flowing through the battery cell 20, i.e., whether to reduce the charge / discharge current flowing through the battery cell 20. The first threshold value Th2 is a value higher than the above-mentioned surface threshold value Th1. The specific value of the first threshold value Th2 is not particularly limited, but may be any value between 60°C and 70°C, for example, 65°C. The first threshold value Th2 is set, for example, to be slightly higher than the upper limit temperature previously set for the battery cell 20. The first threshold value Th2 is pre-stored in the storage unit 101 of FIG. 4.

[0046] Here, if the first determination unit 111 determines that the estimated temperature T.gas of the gasket 62 is equal to or greater than the first threshold value Th2, the process proceeds to step S213 in FIG. 6. In step S213, the charge / discharge current flowing through the battery cell 20 (terminal 50 in this case) is reduced. Here, the current limiting unit 113 in FIG. 4 issues an instruction to reduce the charge / discharge current flowing through the battery cell 20 by a predetermined limit value L1. The limit value L1 here is pre-stored in the storage unit 101 in FIG. 4. The specific value of the limit value L1 is not particularly limited, and may be set to, for example, a value that results in a charge / discharge current that is low enough to allow the vehicle to travel at a minimum. The limit value L1 may be a fixed value or a value that changes depending on the estimated temperature T.gas of the gasket 62. For example, the limit value L1 may decrease as the estimated temperature T.gas increases. In addition, the current limiting unit 113 may issue an instruction to reduce the charge / discharge current to, for example, a control device that controls the overall traveling state of the vehicle. As described above, as shown in Fig. 4, for example, the control device 100 is communicably connected to a vehicle control device 200 that controls the entire vehicle equipped with the battery system 1. The current limiting unit 113 instructs the vehicle control device 200 to reduce the charge / discharge current by a limit value L1. The vehicle control device 200 limits the magnitude of the charge / discharge current so that the charge / discharge current flowing through the battery cell 20 is small, for example, reduced by the limit value L1. After receiving the instruction from the current limiting unit 113 in this way, the process proceeds to step S215 in Fig. 6.

[0047] In this embodiment, even if the first determination unit 111 determines in step S211 of FIG. 6 that the estimated temperature T.gas of the gasket 62 is lower than the first threshold value Th2, the process proceeds to step S215. In step S215, the second determination unit 115 of FIG. 4 determines whether the estimated temperature T.gas of the gasket 62 is equal to or higher than a predetermined second threshold value Th3. The second threshold value Th3 is a value used to determine whether the estimated temperature T.gas of the gasket 62 is too high (here, even higher than the first threshold value Th2). Here, the second threshold value Th3 is a value used to determine whether or not to prohibit the flow of charge / discharge current to the battery cell 20. The second threshold value Th3 is a value higher than the first threshold value Th2 described above. The specific value of the second threshold value Th3 is not particularly limited, but is, for example, any value between 80°C and 90°C, such as 85°C. The second threshold value Th3 is pre-stored in the storage unit 101 of FIG. 4.

[0048] If the second determination unit 115 determines that the estimated temperature T.gas of the gasket 62 is less than the second threshold value Th3, the flow of charge / discharge current to the battery cell 20 is terminated.

[0049] On the other hand, if the second determination unit 115 determines that the estimated temperature T.gas of the gasket 62 is equal to or higher than the second threshold value Th3, the process proceeds to step S217 in FIG. 6. In step S217, the prohibition unit 117 in FIG. 4 prohibits the flow of charge / discharge current to the battery cells 20 (terminals 50 in this case). The method for prohibiting the flow of charge / discharge current is not particularly limited. Here, the prohibition unit 117 turns off the first contactor 81 and the second contactor 82 (see FIG. 1) connected to the battery unit 10. That is, the prohibition unit 117 opens the first contactor 81 and the second contactor 82, thereby disconnecting the battery unit 10 from the load 5. In this way, the prohibition unit 117 can prohibit the flow of charge / discharge current to the battery cells 20 that constitute the battery unit 10. After the first contactor 81 and the second contactor 82 are turned off in step S217, the flowchart in FIG. 6 ends.

[0050] In this embodiment, as shown in FIG. 1, the battery unit 10 includes multiple battery cells 20. The flowchart in FIG. 6 may be executed sequentially for each battery unit 10. When adjusting the charge / discharge current for each battery unit 10, in step S201, the surface temperature T.cell of the case 30 of each battery cell 20 is measured. Then, in step S209, the estimated temperature T.gas may be estimated only for the battery cell 20 with the highest surface temperature T.cell of the case 30 among the multiple battery cells 20. That is, the estimation unit 107 in FIG. 4 may estimate the estimated temperature T.gas of the gasket 62 by adding the estimated temperature increase ΔT.gas(n) to the highest surface temperature T.cell among the surface temperatures T.cell of the multiple battery cells 20. Steps S211 and subsequent steps in FIG. 6 may be executed using the estimated temperature T.gas thus estimated.

[0051] 5 and 6 may be executed for the positive terminal 51 of the terminals 50, or may be executed for the negative terminal 52. Furthermore, the flowcharts of FIGS. 5 and 6 may be executed for both the positive terminal 51 and the negative terminal 52.

[0052] As described above, in this embodiment, as shown in FIG. 1, the battery system 1 includes a battery cell 20, a temperature sensor 94, and a control device 100. As shown in FIG. 2, the battery cell 20 includes a case 30 and a terminal 50 provided on the case 30. The temperature sensor 94 is configured to measure the surface temperature T.cell of the case 30. As shown in FIG. 4, the control device 100 includes a measurement unit 103, a calculation unit 105, and an estimation unit 107. In step S101 of FIG. 5, the measurement unit 103 measures the surface temperature T.cell of the case 30 using the temperature sensor 94. In step S105 of FIG. 5, the calculation unit 105 calculates an estimated temperature rise ΔT.gas(n) based on the amount of heat generated by the charge / discharge current flowing through the terminal 50. In step S107 of FIG. 5, the estimation unit 107 estimates the estimated temperature T.gas of the terminal 50 based on the surface temperature T.cell of the case 30 and the estimated temperature rise ΔT.gas(n). 2, the terminal 50 has a terminal body 61 through which charge / discharge current flows, and a gasket 62 that insulates the terminal body 61 from the case 30. The estimation unit 107 estimates an estimated temperature T.gas of the gasket 62 of the terminal 50.

[0053] This makes it possible to estimate the estimated temperature T.gas of the gasket 62 of the terminal 50 based on the surface temperature T.cell of the case 30 and the estimated temperature rise ΔT.gas(n). Therefore, the estimated temperature T.gas of the gasket 62 can be estimated without directly attaching a temperature sensor 94 to the gasket 62 of the terminal 50. Furthermore, even for a small part such as the gasket 62, the estimated temperature T.gas of the gasket 62 can be estimated based on the surface temperature T.cell of the case 30 and the estimated temperature rise ΔT.gas(n).

[0054] In this embodiment, the calculation unit 105 calculates the estimated temperature rise ΔT.gas(n) using a predetermined first-order lag calculation formula based on the amount of heat generated by the Irms value of the charge / discharge current. The first-order lag calculation formula is expressed by the above-mentioned formula (1). In this way, by calculating the estimated temperature rise ΔT.gas(n) based on the first-order lag calculation formula, it is possible to calculate the estimated temperature rise ΔT.gas(n) more accurately.

[0055] In this embodiment, as shown in FIG. 4 , the control device 100 includes a first determination unit 111 and a current limiting unit 113. The first determination unit 111 determines whether the estimated temperature T.gas of the gasket 62 is equal to or greater than a predetermined first threshold value Th2, as in step S211 of FIG. 6 . When the first determination unit 111 determines that the estimated temperature T.gas is equal to or greater than the first threshold value Th2, the current limiting unit 113 instructs the control device 100 to reduce the charge / discharge current flowing through the terminal 50 (here, the terminal body 61) by a predetermined limit value L1, as in step S213 of FIG. 6 . When the estimated temperature T.gas of the gasket 62 increases, the battery cell 20 may become too hot due to the amount of heat generated by the Irms value of the charge / discharge current, potentially resulting in problems such as inappropriate charging and discharging. Therefore, when the estimated temperature T.gas is equal to or greater than the first threshold value Th2, the charge / discharge current is reduced by the limit value L1, thereby preventing the battery cell 20 from becoming too hot.

[0056] In this embodiment, as shown in FIG. 4 , the control device 100 includes a second determination unit 115 and a prohibition unit 117. As shown in step S215 of FIG. 6 , the second determination unit 115 determines whether the estimated temperature T.gas of the gasket 62 is equal to or greater than a second threshold value Th3, which is higher than the first threshold value Th2. When the second determination unit 115 determines that the estimated temperature T.gas is equal to or greater than the second threshold value Th3, the prohibition unit 117 prohibits the flow of charge / discharge current to the terminal 50 (here, the terminal body 61) as shown in step S217 of FIG. 6 . In this way, when the estimated temperature T.gas of the gasket 62 becomes higher, the battery cell 20 becomes even hotter, which may significantly shorten the lifespan of the battery cell 20. Therefore, by preventing the flow of charge / discharge current to the battery cell 20 when the estimated temperature T.gas is equal to or greater than the second threshold value Th3, it is possible to prevent the battery cell 20 from becoming even hotter.

[0057] In this embodiment, the control device 100 includes a surface determination unit 109 (see FIG. 4) that determines whether the surface temperature T.cell of the case 30 is equal to or lower than a predetermined surface threshold Th1, as in step S203 of FIG. 6. When the surface determination unit 109 determines that the surface temperature T.cell of the case 30 is equal to or lower than the surface threshold Th1, the processes from step S205 onward in FIG. 6 are not executed, and control by the current measurement unit 104, calculation unit 105, estimation unit 107, first determination unit 111, current limiting unit 113, second determination unit 115, and prohibition unit 117 is not performed. In this way, when the surface temperature T.cell of the case 30 is low, the battery cell 20 is unlikely to become hot even when the charge / discharge current is not limited. In such a case, the load on the control device 100 can be reduced by not executing the processes from step S205 onward in FIG. 6.

[0058] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate, unless a particular problem arises.

[0059] As described above, this specification includes the disclosures set forth in the following sections.

[0060] Section 1: A battery cell; A temperature sensor; a current sensor; a control device; Equipped with The battery cell is Case and a terminal provided on the case; Equipped with the temperature sensor is configured to measure a surface temperature of the case; the current sensor is configured to measure a charge / discharge current flowing through the terminal; The control device a measuring unit that measures the surface temperature of the case using the temperature sensor; a calculation unit that calculates an estimated temperature rise based on the amount of heat generated by the charge / discharge current flowing through the terminal; an estimation unit that estimates an estimated temperature of the terminal based on the surface temperature of the case and the estimated temperature rise; A battery system comprising:

[0061] Section 2: The terminal is a terminal body through which the charging / discharging current flows; a gasket for insulating the terminal body from the case; and Item 2. The battery system according to item 1, wherein the estimation unit estimates the estimated temperature of the gasket of the terminal.

[0062] Section 3: 3. The battery system according to item 1 or 2, wherein the calculation unit calculates the estimated temperature rise using a predetermined first-order lag calculation formula based on the amount of heat generated.

[0063] Section 4: When the estimated temperature rise is ΔT.gas(n), the sampling frequency is Ts, the time constant is Tc, the Irms value of the charge / discharge current is Irms, and the previous estimated temperature rise is ΔT.gas(n-1), The calculation formula for the first-order lag system is: ΔT.gas(n)=(Ts / (Ts+Tc))×k×Irms 2 +(Tc / (Ts+Tc))×ΔT.gas(n-1) The battery system described in item 3, represented by:

[0064] Section 5: The control device a first determination unit that determines whether the estimated temperature is equal to or greater than a predetermined first threshold; a current limiting unit that instructs the charging / discharging current flowing through the terminal to be reduced by a predetermined limit value when the first determining unit determines that the estimated temperature is equal to or higher than the first threshold value; The battery system according to any one of items 1 to 4, comprising:

[0065] Item 6: The control device a second determination unit that determines whether the estimated temperature is equal to or greater than a second threshold that is higher than the first threshold; a prohibition unit that prohibits the charge / discharge current from flowing through the terminal when the second determination unit determines that the estimated temperature is equal to or higher than the second threshold; Item 6. The battery system according to item 5, comprising:

[0066] Section 7: The control device includes a surface determination unit that determines whether the surface temperature of the case is equal to or lower than a predetermined surface threshold value. 7. The battery system according to any one of items 1 to 6, wherein when the surface determination unit determines that the surface temperature of the case is equal to or lower than the surface threshold value, control is not performed by the calculation unit and the estimation unit. [Explanation of symbols]

[0067] 1 Battery System 20 battery cells 30 cases 50 terminals 61 Terminal body 62 Gasket 94 Temperature Sensor 100 control device 103 Measuring section 105 Calculation Unit 107 Estimation part 109 Surface determination section 111 1st Judgment Department 113 Current limiter 115 Second Judgment Section 117 Prohibited part

Claims

1. A battery cell; A temperature sensor; a current sensor; a control device; Equipped with The battery cell is Case and a terminal provided on the case; Equipped with the temperature sensor is configured to measure a surface temperature of the case; the current sensor is configured to measure a charge / discharge current flowing through the terminal; The control device a measuring unit that measures the surface temperature of the case using the temperature sensor; a calculation unit that calculates an estimated temperature rise based on the amount of heat generated by the charge / discharge current flowing through the terminal; an estimation unit that estimates an estimated temperature of the terminal based on the surface temperature of the case and the estimated temperature rise; A battery system comprising:

2. The terminal is a terminal body through which the charging / discharging current flows; a gasket for insulating the terminal body from the case; and The battery system according to claim 1 , wherein the estimation unit estimates the estimated temperature of the gasket of the terminal.

3. The battery system according to claim 1 , wherein the calculation unit calculates the estimated temperature rise from a predetermined first-order lag calculation formula based on the amount of heat generated.

4. When the estimated temperature rise is ΔT.gas(n), the sampling frequency is Ts, the time constant is Tc, the Irms value of the charge / discharge current is Irms, and the previous estimated temperature rise is ΔT.gas(n-1), The calculation formula for the first-order lag system is: ΔT.gas(n)=(Ts / (Ts+Tc))×k×Irms ２ +(Tc / (Ts+Tc))×ΔT.gas(n-1) The battery system according to claim 3 , wherein:

5. The control device a first determination unit that determines whether the estimated temperature is equal to or greater than a predetermined first threshold; a current limiting unit that instructs the charging / discharging current flowing through the terminal to be reduced by a predetermined limit value when the first determination unit determines that the estimated temperature is equal to or higher than the first threshold value; The battery system of claim 1 , comprising:

6. The control device a second determination unit that determines whether the estimated temperature is equal to or greater than a second threshold value that is higher than the first threshold value; a prohibition unit that prohibits the charge / discharge current from flowing through the terminal when the second determination unit determines that the estimated temperature is equal to or higher than the second threshold value; The battery system according to claim 5 , comprising:

7. The control device includes a surface determination unit that determines whether the surface temperature of the case is equal to or lower than a predetermined surface threshold value. The battery system according to claim 1 , wherein when the surface determination unit determines that the surface temperature of the case is equal to or lower than the surface threshold value, the calculation unit and the estimation unit do not perform control.

Images