Circuit breaker and storage element

Abstract

To provide a cut out gear and a power storage element capable of detecting an internal short circuit at an early stage and interrupting the current path according to the detection result.SOLUTION: A power storage element 100 having an electrode terminal 310 and an electrode body having a conductive tab 211, with the electrode body connected to the electrode terminal via the conductive tab, has a cut out part (semiconductor switching element 152) that interrupts the current path between the electrode terminal and the electrode body based on a sensor output from a temperature sensor that measures the temperature of the conductive tab.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to a circuit breaker and an energy storage element. [Background technology]

[0002] In recent years, energy storage elements such as lithium-ion batteries have been used in a wide range of fields, including as power sources for notebook personal computers, smartphones and other mobile terminals, renewable energy storage systems, and power sources for IoT devices.

[0003] For example, a porous separator that is filled with an electrolyte and allows ions to move is sandwiched between the positive and negative electrodes of a lithium-ion battery. The separator prevents the positive and negative electrodes from coming into contact with each other, and prevents a short circuit (internal short circuit) from occurring between the positive and negative electrodes (see, for example, Patent Document 1). When an internal short circuit occurs in any energy storage element, not limited to lithium-ion batteries, heat is generated inside the battery, which may cause the battery to break down. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-140100 A Summary of the Invention [Problem to be solved by the invention]

[0005] Because an internal short circuit generates heat inside the battery, it is possible to detect an internal short circuit, for example, by measuring the temperature of the battery surface and detecting a temperature rise on the battery surface. However, because it takes a certain amount of time for the heat generated by an internal short circuit to be transferred to the battery surface, it is difficult to detect an internal short circuit in real time using this method.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a circuit breaker and an energy storage element that can detect an internal short circuit at an early stage and break a current path in accordance with the detection result. [Means for solving the problem]

[0007] The interrupting device includes an electrode terminal and an electrode body having a conductive tab, and for an energy storage element in which the electrode body is connected to the electrode terminal via the conductive tab, includes an interrupting section that interrupts the current path between the electrode terminal and the electrode body based on a sensor output from a temperature sensor that measures the temperature of the conductive tab.

[0008] The energy storage element comprises an electrode terminal and an electrode body having a conductive tab, the electrode body being connected to the electrode terminal via the conductive tab, and is provided with a temperature sensor that measures the temperature of the conductive tab. Effect of the Invention

[0009] According to the present application, an internal short circuit can be detected at an early stage, and a current path can be cut off in accordance with the detection result. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is an external perspective view of the energy storage element. [Diagram 2] FIG. [Diagram 3] FIG. 2 is an exploded perspective view of an electrode body constituting an energy storage element. [Figure 4] FIG. [Diagram 5] FIG. 2 is a block diagram illustrating an internal configuration of a detection device. [Figure 6] FIG. 2 is a circuit diagram showing an equivalent circuit of a storage element. [Figure 7] 1 is a circuit diagram showing an equivalent circuit of a storage element in a state in which an internal short circuit occurs. [Figure 8] FIG. 11 is a circuit diagram showing an equivalent circuit of the combined energy storage elements. [Figure 9]FIG. 2 is a schematic diagram showing a configuration example of a thermal circuit model according to the first embodiment. [Figure 10] 4 is a flowchart illustrating a procedure for detecting an internal short circuit in the first embodiment. [Figure 11] FIG. 11 is a schematic diagram showing a configuration example of a thermal circuit model in the second embodiment. [Figure 12] 13 is a flowchart illustrating a procedure for detecting an internal short circuit in the third embodiment. [Figure 13] 13 is a flowchart illustrating a procedure for detecting an internal short circuit in the fourth embodiment. [Figure 14] 13 is a flowchart illustrating a procedure for detecting an internal short circuit in the fifth embodiment. [Figure 15] 10 is a flowchart illustrating a procedure for detecting a sign of an internal short circuit. [Figure 16] FIG. 13 is a partial cross-sectional view of an energy storage element according to a seventh embodiment. [Figure 17] FIG. 2 is a perspective view showing an example of mounting a circuit breaker. [Figure 18] 4 is a flowchart illustrating a procedure of a process executed by a control circuit. [Figure 19] FIG. 2 is an external perspective view showing a laminate type energy storage element. [Figure 20] FIG. 2 is an exploded perspective view showing a laminate type energy storage element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The interrupting device includes an electrode terminal and an electrode body having a conductive tab, and for an energy storage element in which the electrode body is connected to the electrode terminal via the conductive tab, includes an interrupting section that interrupts the current path between the electrode terminal and the electrode body based on a sensor output from a temperature sensor that measures the temperature of the conductive tab. When an internal short circuit occurs in the energy storage element, the conductive tab heats up more quickly than the electrode body and the container that contains the electrode body. When a temperature rise in the conductive tab is detected, the circuit breaker can prevent the energy storage element from becoming too hot by cutting off the current path between the electrode terminal and the electrode body.

[0012] The circuit breaker may further include a detection unit that detects an internal short circuit in the electrode body based on the sensor output, and the circuit breaker may interrupt the current path between the electrode terminal and the electrode body according to the detection result of the detection unit. With this configuration, the detection unit can detect an internal short circuit at an early stage by referring to the temperature of the conductive tab, and when an internal short circuit is detected, the detection unit can interrupt the current path between the electrode terminal and the electrode body.

[0013] In the circuit breaker, the detection unit may include an observer that estimates a short-circuit resistance of the internal short circuit based on the sensor output. With this configuration, the short-circuit resistance of an internal resistor that cannot be directly observed can be estimated through a state variable obtained from the observer.

[0014] In the circuit breaker, the detection unit may estimate the short-circuit resistance of the internal resistance by using a state estimation algorithm based on the sensor output and a thermal circuit model that simulates a thermal phenomenon of the storage element. With this configuration, the short-circuit resistance of the internal resistance that cannot be directly observed can be estimated by using the state estimation algorithm.

[0015] In the circuit breaker, the thermal circuit model may include the electrode body, the conductive tab, and the short-circuit portion as nodes, and may include the temperature and heat capacity at each node, and the thermal resistance between the nodes as parameters. With this configuration, it is possible to describe the thermal phenomenon in the energy storage element using a simple model.

[0016] In the circuit breaker, the state estimation algorithm may include a procedure of: determining the time transition of each state variable using a state equation expressing the time transition of the state variables including the temperature and short-circuit resistance of each node; determining the likelihood of the state estimation using an observation equation describing the relationship between the state variables and an observation amount including the observed temperature by the temperature sensor; and updating the estimated value of the state variable according to the determined likelihood of the state estimation. With this configuration, the short-circuit resistance of the internal resistance that cannot be directly observed can be estimated in a time series manner through the state variables that are successively updated.

[0017] In the circuit breaker, the state estimation algorithm may include a particle filter, an ensemble Kalman filter, an extended Kalman filter, or an unscented Kalman filter. With this configuration, the particle filter, the ensemble Kalman filter, the extended Kalman filter, or the unscented Kalman filter is used to sequentially update state variables, and the short-circuit resistance of an internal resistance that cannot be directly observed can be estimated in a time series manner.

[0018] In the interrupter, the electrode body may be a laminated electrode body. According to this configuration, the positive electrode plates (or the negative electrode plates) of the energy storage element are connected only via the conductive tab, so that the temperature of the conductive tab rises quickly when an internal short circuit occurs. When a temperature rise of the conductive tab is detected, the interrupter can prevent the energy storage element from becoming too hot by interrupting the current path between the electrode terminal and the electrode body.

[0019] The energy storage element includes an electrode terminal and an electrode body having a conductive tab, the electrode body being connected to the electrode terminal via the conductive tab, and a temperature sensor for measuring the temperature of the conductive tab. Since the energy storage element includes the temperature sensor for measuring the temperature of the conductive tab, it is possible to observe a state that changes relatively quickly when an internal short circuit occurs.

[0020] The energy storage element may further include a cutoff section that cuts off the current path between the electrode terminal and the electrode body based on a sensor output from the temperature sensor. According to this configuration, when an internal short circuit of the energy storage element is detected, the current path between the electrode terminal and the electrode body is cut off, thereby preventing the energy storage element from becoming too hot.

[0021] Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof. (Embodiment 1) Fig. 1 is an external perspective view of the energy storage element 100, Fig. 2 is an exploded perspective view of the energy storage element 100, Fig. 3 is an exploded perspective view of an electrode body 200 constituting the energy storage element 100, and Fig. 4 is a partial cross-sectional view near the terminals. The energy storage element 100 is, for example, a lithium ion secondary battery. The energy storage element 100 stores power supplied from an external charging device and supplies the stored power to a predetermined load. The energy storage element 100 is used as a power source for automobiles (or mobile objects) such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), a power source for aviation, a power source for space, a power source for electronic devices, a power source for power storage, and the like.

[0022] The energy storage element 100 includes an electrode assembly 200 (see FIG. 2) housed in a container 110, and electrode terminals 310, 320 connected to an external charging device or load. One electrode terminal 310 is a positive electrode terminal, and the other electrode terminal 320 is a negative electrode terminal. The electrode assembly 200 is electrically connected to the electrode terminals 310, 320 via conductive tabs (a positive electrode tab 211 and a negative electrode tab 221, which will be described later).

[0023] The container 110 is composed of a rectangular parallelepiped container body 111 and a lid 112 that closes the opening of the container body 111. The container body 111 and the lid 112 are made of a weldable metal, such as stainless steel, aluminum, or an aluminum alloy. Alternatively, the container body 111 and the lid 112 may be made of a resin. The container body 111 is sealed by the lid 112 after accommodating the electrode body 200 and the like. An electrolyte (not shown) is sealed inside the container 110. As the electrolyte, for example, an electrolyte containing a supporting salt in an organic solvent is used. As the organic solvent, for example, an aprotic solvent such as carbonates, esters, or ethers is used. As the supporting salt, for example, a lithium salt such as LiPF6, LiBF4, or LiClO4 is suitably used. The electrolyte may contain various additives, such as a gas generating agent, a film forming agent, a dispersing agent, and a thickener. The lid 112 may include an inlet for injecting an electrolyte into the container 110, a gas exhaust valve for exhausting gas from inside the container when the internal pressure of the container 110 increases, and the like.

[0024] The electrode terminals 310, 320 of the energy storage element 100 are attached to the lid 112 of the container 110 by crimping or the like. Specifically, the electrode terminals 310, 320 each have an axis (rivet portion) extending downward, and this axis is inserted into through-holes in the upper gasket 120, the lid 112, the lower gasket 130, and the current collector 140 and crimped. In this way, the electrode terminals 310, 320 are attached to the lid 112 of the container 110 together with the upper gasket 120, the lid 112, the lower gasket 130, and the current collector 140.

[0025] Here, the upper gasket 120 is a flat sealing member disposed between the lid 112 of the container 110 and the electrode terminals 310, 320. The lower gasket 130 is a sealing member disposed between the lid 112 of the container 110 and the current collector 140. The upper gasket 120 and the lower gasket 130 are formed of an insulating resin material such as polypropylene (PP), polyethylene (PE), polyphenylene sulfide resin (PPS), or the like.

[0026] The current collector 140 is a rectangular flat conductive member that electrically connects the electrode terminals 310, 320 and the conductive tabs (positive electrode tab 211 and negative electrode tab 221) of the electrode body 200. The current collector 140 is formed of a material such as a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The positive electrode side current collector 140 is connected to the electrode terminal 310 by crimping or the like, and is connected to the positive electrode tab 211 provided on the electrode body 200 by welding or the like. Similarly, the negative electrode side current collector 140 is connected to the electrode terminal 320 by crimping or the like, and is connected to the negative electrode tab 221 provided on the electrode body by welding or the like. Alternatively, the current collector 140 may be connected to the electrode terminals 310, 320 by a method such as welding or screw fastening, or may be connected to the positive electrode tab 211 and the negative electrode tab 221 by a method such as crimping or screw fastening.

[0027] The electrode body 200 is a laminate of a positive electrode plate 210, a negative electrode plate 220, and a separator 230. The electrode body 200 shown as an example in Fig. 3 is made of a laminate in which the separator 230, the negative electrode plate 220, the separator 230, the positive electrode plate 210, ... are repeatedly laminated in this order.

[0028] The positive electrode plate 210 is composed of a substrate and a positive electrode active material layer formed on the substrate. The substrate of the positive electrode plate 210 is a current collector foil. The current collector foil is made of known materials such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymer, conductive glass, and Al-Cd alloy. The positive electrode active material layer includes a positive electrode active material, a conductive assistant, and a binder. The positive electrode active material is a material capable of absorbing and releasing lithium ions. Examples of the positive electrode active material include polyanion compounds such as LiMPO4, LiMSiO4, and LiMBO3 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), LiMn2O4, LiMn 1.5 Ni 0.5 Spinel-type lithium manganese oxides such as O4, lithium transition metal oxides such as LiMO2 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc., including lithium-rich composite oxides), etc. are used. Carbon black such as acetylene black (AB) and other carbon materials (graphite, etc.) are preferably used as the conductive assistant. Materials such as polyvinylidene fluoride (PVDF) are used as the binder.

[0029] The positive electrode plate 210 includes a positive electrode tab 211. The positive electrode tab 211 is a rectangular conductive tab protruding from one side of the positive electrode plate 210. The positive electrode tab 211 is formed integrally with the substrate (current collecting foil). The positive electrode tabs 211 of the positive electrode plates 210 are bundled together to form a tab bundle.

[0030] The negative electrode plate 220 is composed of a substrate and a negative electrode active material layer formed on the substrate. The substrate of the negative electrode plate 220 is a current collector foil. The current collector foil is made of the same material as the current collector foil constituting the substrate of the positive electrode plate 210. The negative electrode active material layer includes a negative electrode active material, a conductive assistant, and a binder. The negative electrode active material is made of a material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include lithium metal, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloy), alloys capable of absorbing and releasing lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxides, metal oxides, lithium metal oxides (Li4Ti5O 12 etc.), polyphosphate compounds, and compounds of transition metals such as Co3O4 and Fe2P and elements of groups 14 to 16, generally called conversion negative electrodes. The conductive additive and binder are the same materials as those of the conductive additive and binder constituting the positive electrode active material layer.

[0031] The negative electrode plate 220 includes a negative electrode tab 221. The negative electrode tab 221 is a rectangular conductive tab that protrudes from one side of the negative electrode plate 220 at a position that does not overlap with the positive electrode tab 211. The negative electrode tab 221 is formed integrally with the base material (current collector foil). The negative electrode tabs 221 of each negative electrode plate 220 are bundled together to form a tab bundle.

[0032] The separator 230 is a rectangular sheet having microporosity. For example, a woven fabric or nonwoven fabric insoluble in an organic solvent, or a synthetic resin microporous film made of a polyolefin resin such as polyethylene, is used as the material of the separator 230. The separator 230 may be configured by laminating a plurality of microporous films having different materials, weight average molecular weights, porosities, etc., and may be configured to contain appropriate amounts of additives such as various plasticizers, antioxidants, and flame retardants in these microporous films, or may be configured by coating one or both sides of these microporous films with inorganic oxides such as silica.

[0033] In the first embodiment, a lithium ion secondary battery having a laminated electrode body 200 has been described as the energy storage element 100. Alternatively, the energy storage element 100 may be a lithium ion secondary battery having a wound electrode body. The energy storage element 100 may be a cylindrical lithium ion battery or a laminated lithium ion battery. The energy storage element 100 may be an all-solid-state lithium ion battery using a solid electrolyte, or a metallic lithium secondary battery using metallic lithium in the negative electrode. Furthermore, the energy storage element 100 may be a battery other than a lithium ion secondary battery, such as a zinc-air battery, a sodium ion battery, or a lead battery, or a capacitor such as an electric double layer capacitor.

[0034] Not only in the above-mentioned energy storage element 100, but in other energy storage elements as well, the positive and negative plates are provided at a distance from each other so as not to come into contact with each other. As a result, short circuits (internal short circuits) between the positive and negative plates are avoided. In such an energy storage element, if a foreign object gets into the container or if the separator is damaged, insulation between the positive and negative plates is no longer maintained, and an internal short circuit may occur. If an internal short circuit occurs in the energy storage element, heat is generated inside the battery, leading to battery failure.

[0035] Since an internal short circuit generates heat inside the battery, it is possible to detect an internal short circuit, for example, by measuring the temperature of the battery surface and detecting a temperature rise on the battery surface. However, it takes a certain amount of time for the heat generated by an internal short circuit to be transmitted to the battery surface, so it is difficult to detect an internal short circuit in real time using this method. In addition, it is difficult to actually measure the resistance of an internal short circuit, and there was no technology to grasp the resistance of an internal short circuit.

[0036] Therefore, in the first embodiment, in the detection device 10 described below, a simulation is performed with reference to the temperature of a conductive tab provided in the electrode body 200 of the energy storage element 100, and an internal short circuit in the energy storage element 100 is detected based on the results of the simulation. For example, the detection device 10 estimates the short circuit resistance of the internal short circuit by the simulation, and when the estimated short circuit resistance is less than a threshold value, it determines that an internal short circuit in the energy storage element 10 has been detected. Alternatively, the maximum temperature of the conductive tab may be obtained under various usage conditions (such as current value during charging or discharging and current application time) that are assumed in advance, and when the tab temperature during actual operation is higher than the previously obtained maximum temperature by a certain percentage or by a certain temperature or more, the detection device 10 may determine that an internal short circuit has been detected. Furthermore, the temperature of the conductive tab under various assumed usage conditions (such as current value during charging or discharging and current flow time) may be obtained by experiment or simulation to clarify the relationship between the usage conditions and the tab temperature in advance, and if the tab temperature during actual operation is higher by a certain percentage or by a certain temperature or more than the tab temperature under the relevant usage conditions, the detection device 10 may determine that an internal short circuit has been detected.

[0037] The configuration of the detection device 10 that executes the simulation will be described below. FIG. 5 is a block diagram for explaining the internal configuration of the detection device 10. The detection device 10 is a dedicated or general-purpose computer including a calculation unit 11, a storage unit 12, an input unit 13, and an output unit 14. In the example of FIG. 5, the detection device 10 is provided outside the energy storage element 100. Specifically, the detection device 10 may be a battery management unit (BMU) that is provided outside the energy storage element 100, or may be a computer such as a server that is installed in a remote location. Alternatively, the detection device 10 may be built into the energy storage element 100.

[0038] The calculation unit 11 is a calculation circuit including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The CPU included in the calculation unit 11 executes various computer programs stored in the ROM and the storage unit 12, and controls the operation of each of the above-mentioned hardware components, thereby causing the entire device to function as the detection device of the present application. Specifically, the calculation unit 11 estimates the short-circuit resistance in the energy storage element 100 using a state estimation algorithm based on the sensor output of a temperature sensor 250 that measures the temperature of the conductive tabs (positive electrode tab 211, negative electrode tab 221) and a thermal circuit model MD1 that simulates the thermal phenomenon of the energy storage element 100. The calculation unit 11 detects an internal short circuit in the energy storage element 100 based on the estimation result of the short-circuit resistance.

[0039] The calculation unit 11 is not limited to the above configuration, and may be any processing circuit or calculation circuit including multiple CPUs, a multi-core CPU, a GPU (Graphics Processing Unit), a microcomputer, a volatile or non-volatile memory, etc. The calculation unit 11 may also have functions such as a timer that measures the elapsed time from when a measurement start instruction is given to when a measurement end instruction is given, a counter that counts numbers, and a clock that outputs date and time information.

[0040] The storage unit 12 is a storage device such as a flash memory. Various computer programs and data are stored in the storage unit 12. The computer programs stored in the storage unit 12 include, for example, a state estimation program PG for causing the calculation unit 11 to execute calculations based on a state estimation algorithm. The data stored in the storage unit 12 include parameters used in the state estimation program PG, parameters used in a short-circuit equivalent circuit model and a thermal circuit model MD1 described later, and data temporarily generated by calculations by the calculation unit 11. The state estimation program PG is provided, for example, by a non-transient recording medium M on which the computer program is readably recorded. The recording medium M is a portable memory such as a CD-ROM, a USB memory, or an SD (Secure Digital) card. The calculation unit 11 reads a desired computer program from the recording medium M using a reading device not shown in the figure, and stores the read computer program in the storage unit 12. Alternatively, the computer program may be provided by communication.

[0041] The input unit 13 includes an interface for connecting the temperature sensor 250, and acquires a sensor output from the temperature sensor 250. The temperature sensor 250 is an existing sensor such as a thermocouple or a thermistor. The temperature sensor 250 is connected to one or more of the positive electrode tab 211 or the negative electrode tab 221 constituting the conductive tab. Alternatively, the temperature sensor 250 may be connected to the current collector 140 to which the conductive tab is joined. In the first embodiment, the number of the temperature sensors 250 is one. Alternatively, the number of the temperature sensors 250 may be more than one. The temperature sensor 250 may be connected to the input unit 13 by wire or wirelessly.

[0042] The output unit 14 includes an interface for connecting an external device. An example of the external device is a display device 20 such as a liquid crystal display. Alternatively, the external device may be a terminal device (not shown) such as a computer or a smartphone used by a user. The calculation unit 11 outputs the detection result of the internal short circuit to the external device from the output unit 14. The calculation unit 11 may output an estimated value of the short circuit resistance from the output unit 14 to the external device in addition to the detection result of the internal short circuit.

[0043] The detection device 10 may include a notification unit such as an LED lamp or a buzzer to notify the user of the result of the detection of an internal short circuit.

[0044] The details of the calculation process executed by the detection device 10 will be described below. In the first embodiment, an equivalent circuit of the energy storage element 100 is introduced to calculate the current during an internal short circuit. FIG. 6 is a circuit diagram showing the equivalent circuit of the energy storage element 100. In a typical laminated liquid type lithium ion battery, each layer is electrically connected in parallel. Therefore, the equivalent circuit of the energy storage element 100 is represented by, for example, a parallel circuit as shown in FIG. 6. The equivalent circuit shown in FIG. 6 represents a five-layer laminated battery. The number of layers is set appropriately depending on the number of positive electrode plates 210 and negative electrode plates provided in the electrode body 200 of the energy storage element 100.

[0045] Each layer of the energy storage element 100 is divided into a positive electrode tab 211, a battery section, and a negative electrode tab 221. The battery section includes a positive electrode plate 210, a separator 230, a negative electrode plate 220, an electrolyte, etc. In the equivalent circuit, the positive electrode tab 211 is a positive electrode tab resistance (resistance value r ptab ), and the negative electrode tab 221 is represented as a negative electrode tab resistance (resistance value r ntab The battery part is expressed as an equilibrium potential (voltage value E eq ) and the internal resistance (resistance value r e Here, the internal resistance of the battery unit includes the ohmic resistance of the electrodes, the reaction resistance of the electrodes, and the ohmic resistance of the electrolyte.

[0046] In the equivalent circuit shown in Fig. 6, for simplification, each layer of the energy storage element 100 is divided into three parts: the positive electrode tab 211, the battery part, and the negative electrode tab 221, but it may be divided more finely. Also, in the equivalent circuit in Fig. 6, it is assumed that the external short-circuit layers are in the same state, but different states may be set for each external short-circuit layer.

[0047] FIG. 7 is a circuit diagram showing an equivalent circuit of the energy storage element 100 in a state where an internal short circuit has occurred. The equivalent circuit shown as an example in FIG. 7 shows an equivalent circuit in which the fifth layer is an internal short circuit layer and the first to fourth layers are external short circuit layers. The internal short circuit occurs when a short circuit resistor (resistance value R s The same applies when an internal short circuit occurs in another layer.

[0048] In the equivalent circuit, each layer (1st to 4th layers) of the external short circuit layer can be regarded as the same, so that each element of the external short circuit layer can be described by combining them. FIG. 8 is a circuit diagram showing an equivalent circuit of the energy storage element 100 after combining. The combined positive electrode tab resistance (r ptab,ex ), combined internal resistance (r e,ex ), combined negative tab resistance (r ntab,ex ) is written as follows:

[0049]

number

[0050] Here, n is the total number of layers. In this example, n=5. Since the layers are in parallel, the equilibrium potential is E eq It is.

[0051] The current flowing through the external short circuit layer is I ex , the current flowing through the internal short circuit layer is I in , the current flowing through the short circuit is I s Let us assume that ex is the sum of the currents flowing through all the external short-circuit layers, and the current per layer is I ex In the example of FIG. 8, the internal resistance of the battery in the internal short circuit layer is calculated by dividing the internal resistance of the battery in the external short circuit layer (r e,ex) to distinguish it from e,in It is written as follows.

[0052] In the equivalent circuit shown in FIG. 8, when the law of conservation of current is applied, Equation 2 is obtained.

[0053]

number

[0054] When Kirchhoff's law is applied to a closed circuit consisting of the outer short circuit layer, the tab portion of the inner short circuit layer, and the short circuit portion, the following formula 3 is obtained.

[0055]

number

[0056] When Kirchhoff's law is applied to a closed circuit consisting of an internal short circuit layer and a short circuit portion, the following formula 4 is obtained.

[0057]

number

[0058] By solving equations 2 to 4, the current I flowing through the internal short circuit layer is in , the current flowing through the external short circuit layer I ex , the current flowing through the short circuit I s can be obtained as shown in Equations 5 to 7, respectively.

[0059]

number

[0060]

number

[0061]

number

[0062] In Equations 5 to 7, the short-circuit resistance R s All resistances other than are known because they are determined by the design values ​​(material properties, shape). On the other hand, the short-circuit resistance R s cannot be determined by design and is impossible to measure.

[0063] In the first embodiment, a thermal circuit model MD1 that simulates a thermal phenomenon of the energy storage element 100 is introduced to calculate the temperature during an internal short circuit. FIG. 9 is a schematic diagram showing an example of the configuration of the thermal circuit model MD1 in the first embodiment. The thermal circuit model MD1 is a model for simulating a thermal phenomenon of the energy storage element 100 by using the temperatures of a plurality of regions that divide the energy storage element 100 and the thermal resistance between the regions as parameters. The thermal circuit model MD1 shown in FIG. 9 divides the energy storage element 100 into seven regions (region 1 to region 7). Regions 1 to 7 correspond to the internal short circuit layer, the external short circuit layer, the positive electrode tab connected to the internal short circuit layer, the positive electrode tab connected to the external short circuit layer, the negative electrode tab connected to the internal short circuit layer, the negative electrode tab connected to the external short circuit layer, and the short circuit portion, respectively. In the thermal circuit model MD1, the temperatures of regions 1 to 7 are represented as T1 to T7, and the thermal resistance between region i and region j is represented as R ij (i, j = 1 to 7). For example, temperature T1 is the temperature of the internal short circuit layer (battery temperature), temperature T2 is the temperature of the external short circuit layer (battery temperature), and thermal resistance R 12 represents the thermal resistance between the internal short circuit layer and the external short circuit layer. The temperatures of other regions and the thermal resistance between other regions are also shown in Figure 9.

[0064] From the thermal circuit model MD1 shown in FIG. 9, the thermal conduction equation for temperatures T1 to T7 is expressed as in Equation 8.

[0065]

number

[0066] Here, C pi is the specific heat of region i, V i is the volume of region i, ρ iis the density of region i. Q1 to Q7 represent heat generated by current flow (Joule heat and electrochemical reaction heat). For simplification, in the heat conduction equation shown in Equation 8, it is assumed that there is no heat release outside the battery, and all heat generated by the short circuit current is used to increase the temperature of the battery. Alternatively, a heat conduction equation that takes into account heat release outside the battery may be used.

[0067] By rearranging the terms in equation 8 and rewriting the time derivative on the left side as a difference, equation 9 is obtained. In equation 9, Δt represents the time step size of the calculation, and the superscripts k and k+1 represent the number of steps (time steps).

[0068]

number

[0069] In the formula 9, α j =Δt / ρ j C pj V j By putting this together and rearranging it, we get the number 10.

[0070]

number

[0071] In the formula 10, the heat generation amount Q1 in each region k ~Q7 k is expressed as follows:

[0072]

number

[0073] Here, the current I flowing through the internal short circuit layer in , the current flowing through the external short circuit layer I ex , the current flowing through the short circuit I s are written as Equation 5 to Equation 7, respectively. In Equation 5 to Equation 7 and Equation 11, the unknown parameters are the short-circuit resistance R s Only. Heat generation Q1 k ~Q7k is the short circuit resistance R s To make it clear that this is a function of Q i k =Q i k (R s ), the number 10 can be rewritten as follows:

[0074]

number

[0075] Short circuit resistance R s In order to estimate the short-circuit resistance R s is added as a state quantity (=latent variable). The detection device 10 has the calculation unit 11 function as an observer, and solves the eight state variables shown in Expression 13 using eight equations.

[0076]

number

[0077] In order to perform state estimation while suppressing disturbances in the system and observations, a disturbance term may be added. Although the disturbance term is not essential, it may be preferable to add it in order to improve the progress of calculations. The equation with the disturbance term added is written as shown in Equation 14. In Equation 14, v T1 k ~v T7 k ,v Rs k is the disturbance term.

[0078]

number

[0079] Equation 14 can be rewritten as follows:

[0080]

number

[0081] where x k is a vector (state vector) whose elements are state quantities, and v k is a vector having disturbance amounts as elements (disturbance vector). f represents a nonlinear differential equation shown in Equation 14.

[0082] In the first embodiment, the temperature sensor 250 is attached to the positive electrode tab 211. However, even if an internal short circuit occurs, it is not possible to know in which layer the internal short circuit has occurred. Therefore, even if an internal short circuit occurs, it is not possible to know whether the measurement value of the temperature sensor 250 represents the temperature of the positive electrode tab 211 connected to the internal short circuit layer or the temperature of the positive electrode tab 211 connected to the external short circuit layer. However, since the temperature rise of the tab of the external short circuit layer is more gentle than the temperature rise of the tab of the internal short circuit layer, a safety margin can be ensured by considering the measurement value of the temperature sensor 250 as the temperature of the positive electrode tab 211 connected to the external short circuit layer. In the following, it is assumed that the measurement value of the temperature sensor 250 is the temperature of the positive electrode tab 211 connected to the external short circuit layer.

[0083] The observation equation is expressed as shown in Equation 16.

[0084]

number

[0085] where y k is the observed value, c T is the observation vector, w k is the observed disturbance. The temperature T4 of the positive electrode tab 211 connected to the external short circuit layer k x k Since it is the fourth component of T is expressed as follows. The T on the right side of c stands for transposition.

[0086]

number

[0087] In the above observation equation, it has been assumed that there is only one observation. Alternatively, there may be multiple observations.

[0088] The detection device 10 according to the first embodiment utilizes a particle filter to sequentially calculate time updates of a time series model represented by the state equation of Equation 15 and the observation equation of Equation 16, and calculates an internal resistance R s The detection device 10 calculates the internal resistance R s Based on this, an internal short circuit in the energy storage element 100 is detected.

[0089] The procedure for detecting an internal short circuit will now be described. 10 is a flowchart illustrating the procedure for detecting an internal short circuit in the embodiment 1. The calculation unit 11 of the detection device 10 provides an initial value of k=1 (step S101). The calculation unit 11 may provide the environmental temperature as the initial value of the temperature, and a provisional value set in advance as the initial value of the short circuit resistance.

[0090] Next, the calculation unit 11 generates N particles for each state variable (step S102). Here, N is 10 2 ~10 6 A degree of number is usually used.

[0091] Next, the calculation unit 11 calculates v k A random number corresponding to (step S103) is generated.

[0092] The calculation unit 11 executes the calculation based on Equation 18 for all N particles, thereby updating the states of the particles to the states of the particles in the next time step (step S104).

[0093]

number

[0094] The calculation unit 11 acquires the sensor output of the temperature sensor 250 through the input unit 13 (step S105), and calculates particle weights Pk (i) (Step S106). The weight of a particle is calculated by the state vector x k When we obtain the observed value y k is the probability (likelihood) of observing and is described by the following equation:

[0095]

number

[0096] The calculation unit 11 calculates the particle weight P k (i) is normalized based on the following equation (step S107).

[0097]

number

[0098] The calculation unit 11 calculates a vector obtained by taking a weighted average of the particle weights and the state vector as an estimated value by the particle filter (step S108). The calculation formula is as shown in Equation 21. By this calculation, an estimated value of the temperature of each region and an estimated value of the short-circuit resistance are obtained.

[0099]

number

[0100] Next, the calculation unit 11 estimates the presence or absence of an internal short circuit in the energy storage element 100 based on the estimated value of the short circuit resistance. For example, the calculation unit 11 determines whether or not the estimated value of the short circuit resistance is less than a threshold value (step S109). The threshold value is set arbitrarily.

[0101] If the estimated value of the short-circuit resistance is not less than the threshold value (S109: NO), it is estimated that no internal short circuit has occurred in the energy storage element 100. If it is estimated that no internal short circuit has occurred, the calculation unit 11 resamples (stratified sampling) the particles for estimation of the next time step (step S110). The calculation unit 11 resamples the state vector x k (i) HAp k (i) Then, the state vector at time step k+1 can be determined by assuming that the particles are resampled in proportion to the state vector k, and the calculation unit 11 returns the process to step S102 after resampling the particles.

[0102] If the estimated value of the short-circuit resistance is less than the threshold value (S109: YES), it is estimated that an internal short circuit has occurred in the energy storage element 100. If it is estimated that an internal short circuit has occurred, the calculation unit 11 notifies the occurrence of an internal short circuit (step S111). For example, the calculation unit 11 generates text information indicating that an internal short circuit has occurred, and outputs the text information to the display device 20 from the output unit 14, thereby causing the display device 20 to display the text information. Alternatively, the calculation unit 11 may notify a terminal device (not shown) of the text information indicating that an internal short circuit has occurred from the output unit 14. Furthermore, the calculation unit 11 may urge the user to stop using or replace the energy storage element 100, or may ask the user to decide whether to stop using or replace the energy storage element 100.

[0103] As described above, the detection device 10 in the first embodiment detects an internal short circuit in the energy storage element 100 based on the sensor output of the temperature sensor 250 that measures the temperature of the conductive tab. When an internal short circuit occurs in the energy storage element 100, the conductive tab rises in temperature more quickly than the container 110 and the electrode body 200, and therefore the detection device 10 can detect the internal short circuit early by estimating the short circuit resistance based on the temperature of the conductive tab.

[0104] As long as the temperature inside the battery can be accurately measured with almost no time lag, the attachment position of the temperature sensor 250 is not limited to the conductive tab. For example, the temperature sensor 250 may be attached to the electrode terminals 310, 320 (more preferably, the rivet portion of the electrode terminals 310, 320). Alternatively, the temperature sensor 250 may be attached to the current collector 140 or a bus bar (not shown). Alternatively, the temperature sensor 250 may be attached to the outer surface of the container 110 that contains the electrode body 200. When the electrode body 200 is covered with an insulating bag and in contact with the inner surface of the container 110, the temperature of the container 110 rises quickly with the rise in temperature of the electrode body 200. For this reason, by estimating the short circuit resistance based on the temperature of the container 110, an internal short circuit can be detected early. In particular, when the electrode body 200 is in contact with the inner long side of the container 110 via the insulating bag, the temperature sensor 250 may be attached to the outer long side of the container 110.

[0105] The detection device 10 in the first embodiment estimates the short-circuit resistance by using a particle filter. The particle filter is a filter method for a state space model having nonlinearity or non-Gaussianity, and can be used for a more general state space model without assuming linearity or Gaussianity. In addition, the particle filter has a relatively simple algorithm and can be easily implemented in the detection device 10.

[0106] (Embodiment 2) In the second embodiment, a configuration will be described in which a temperature sensor 250 is attached to a tab bundling section where a plurality of positive electrode tabs 211 (or a plurality of negative electrode tabs 221) are bundled, and an internal short circuit is detected based on the sensor output of this temperature sensor 250.

[0107] In the second embodiment, the temperature sensor 250 is attached to a tab bundling portion where a plurality of positive electrode tabs 211 (or a plurality of negative electrode tabs 221) are bundled together. In the second embodiment, it is assumed that the temperature of the tab of the internal short-circuit layer is the same as the temperature of the tab of the external short-circuit layer.

[0108] FIG. 11 is a schematic diagram showing an example of the configuration of a thermal circuit model MD2 in the second embodiment. The thermal circuit model MD2 is a model for simulating thermal phenomena in the energy storage element 100 by using the temperatures of a plurality of regions dividing the energy storage element 100 and the thermal resistance between the regions as parameters. The thermal circuit model MD2 shown in FIG. 11 divides the energy storage element 100 into five regions (region 1 to region 5). Region 1 to region 5 correspond to the internal short-circuit layer, the external short-circuit layer, the positive electrode tab, the negative electrode tab, and the short circuit portion, respectively. In the thermal circuit model MD2, the temperatures of regions 1 to 5 are represented as T1 to T5, and the thermal resistance between region i and region j is represented as R ij (i, j = 1 to 5). For example, temperature T1 is the temperature of the internal short circuit layer (battery temperature), temperature T2 is the temperature of the external short circuit layer (battery temperature), and thermal resistance R 12 represents the thermal resistance between the internal short circuit layer and the external short circuit layer. The temperatures of other regions and the thermal resistance between other regions are also shown in Figure 11.

[0109] From the thermal circuit model MD2 shown in FIG. 11, the heat conduction equation for temperatures T1 to T5 is expressed as in Equation 22.

[0110]

number

[0111] Here, C pi is the specific heat of region i, V i is the volume of region i, ρ i is the density of region i. Q1 to Q5 represent heat generated by current flow (Joule heat and electrochemical reaction heat). For simplification, in the heat conduction equation shown in Equation 22, it is assumed that there is no heat release to the outside of the battery, and all heat generated by the short circuit current is used to increase the temperature of the battery. Alternatively, a heat conduction equation that takes into account heat release to the outside of the battery may be used.

[0112] By rearranging the terms in Equation 22 and rewriting the time derivative on the left side as a difference, we obtain Equation 23. In Equation 23, Δt represents the time step size of the calculation, and the superscripts k and k+1 represent the number of steps (time steps).

[0113]

number

[0114] In the formula 23, α j =Δt / ρ j C pj V j Putting this together and rearranging it, we get the number 24.

[0115]

number

[0116] In equation 24, the heat generation amount Q1 in each region k ~Q5 k is expressed as follows:

[0117]

number

[0118] Here, the current I flowing through the internal short circuit layer in , the current flowing through the external short circuit layer I ex , the current flowing through the short circuit I s As described in the first embodiment, these are written as Equations 5 to 7, respectively. In Equations 5 to 7 and Equation 25, the unknown parameters are the short-circuit resistance R s Only. Heat generation Q1 k ~Q5 k is the short circuit resistance R s To make it clear that this is a function of Q i k =Q i k (R s ), the number 24 can be rewritten as follows:

[0119]

number

[0120] Short circuit resistance R sIn order to estimate the short-circuit resistance R s is added as a state quantity (=latent variable). The detection device 10 makes the calculation unit 11 function as an observer and solves the six state variables shown in Expression 27 by six equations.

[0121]

number

[0122] In addition, a disturbance term may be added to suppress disturbances in the system or observations. Although the disturbance term is not essential, it is preferable to add it in order to improve the progress of the calculation. The equation with the disturbance term added is written as shown in Equation 28. In Equation 28, v T1 k ~v T5 k ,v Rs k is the disturbance term.

[0123]

number

[0124] Equation 28 can be rewritten as follows:

[0125]

number

[0126] where x k is a vector (state vector) whose elements are state quantities, and v k is a vector (disturbance vector) whose elements are disturbance amounts. f represents a nonlinear differential equation shown in Equation 28.

[0127] In the observation, a part of the state quantities is observed. In the following, it is assumed that the measurement value of the temperature sensor 250 is the temperature of the bundling part where the positive electrode tabs 211 are bundled.

[0128] The observation equation is expressed as follows:

[0129]

number

[0130] where y k is the observed value, c T is the observation vector, w k is the observed disturbance. The temperature T3 of the binding part of the positive electrode tab 211 k x k Since it is the third component of T is expressed as follows. The T on the right side of c stands for transposition.

[0131]

number

[0132] In the above observation equation, it has been assumed that there is only one observation. Alternatively, there may be multiple observations.

[0133] As in the first embodiment, the detection device 10 uses a particle filter to sequentially calculate time updates of a time series model represented by the state equation of Equation 29 and the observation equation of Equation 30, and calculates the internal resistance R s The detection device 10 calculates the internal resistance R s Based on this, an internal short circuit in the energy storage element 100 is detected.

[0134] As described above, in the second embodiment, the temperature sensor 250 is provided at the tab bundling portion where the multiple positive electrode tabs 211 (or multiple negative electrode tabs 221) are bundled, and therefore it is easy to attach the temperature sensor 250. In the second embodiment, the thermal circuit model MD2 is simplified and the number of parameters is reduced, making calculations easier.

[0135] (Embodiment 3) In the third embodiment, a state estimation algorithm using an ensemble Kalman filter will be described. That is, the detection device 10 in the third embodiment uses an ensemble Kalman filter to sequentially calculate time updates of a time series model represented by a state equation of Expression 15 and an observation equation of Expression 16, and calculates an internal resistance R s The detection device 10 calculates the internal resistance R s Based on this, an internal short circuit in the energy storage element 100 is detected.

[0136] FIG. 12 is a flow chart for explaining the procedure for detecting an internal short circuit in the third embodiment. The calculation unit 11 of the detection device 10 provides an initial value of k=1 (step S121). The calculation unit 11 provides the environmental temperature as the initial value of the temperature, and provides a tentative value set in advance as the initial value of the short circuit resistance. The disturbance term v in the state equation is k and the disturbance term w in the observation equation k The variance of each is Q k and R k Let us assume that.

[0137] Next, the calculation unit 11 generates N particles for each state variable (step S122). Here, N is 10 2 ~10 6 A degree of number is usually used.

[0138] Next, the calculation unit 11 calculates v k A random number corresponding to v is generated (step S123). k is assumed to follow a normal distribution and the variance is known.

[0139] The calculation unit 11 executes the calculation based on Equation 18 for all N particles, thereby updating the states of the particles to the states of the particles in the next time step (step S124).

[0140]

number

[0141] The calculation unit 11 calculates the difference x between the state vector of each particle (i=1, 2, ..., N) and the average value of the state vectors of all particles. k (i) Calculate x_bar (step S125). k (i) _bar is represented by the number 33.

[0142]

number

[0143] The calculation unit 11 calculates the covariance matrix P k (Step S126) The covariance matrix P k is expressed by the number 34.

[0144]

number

[0145] The calculation unit 11 acquires the sensor output of the temperature sensor 250 through the input unit 13 (step S127). The acquired sensor output of the temperature sensor 250 is the observed value y k i Gives.

[0146] The calculation unit 11 calculates the measurement error r k i (Step S128). Here, w k is the observed disturbance. The observation error r k i is expressed by the number 35.

[0147]

number

[0148] The calculation unit 11 calculates the Kalman gain K at time step k. k (Step S129). The Kalman gain K kis expressed by the number 36.

[0149]

number

[0150] The calculation unit 11 calculates the estimated value x of the i-th particle. k (i) _hat is calculated (step S130). k (i) hat is expressed by the formula 37. That is, the calculation unit 11 converts the initial predicted value of the formula 32 into the observation error r k i and the Kalman gain K of number 36 k and are used to correct it.

[0151]

number

[0152] The calculation unit 11 calculates the average value x of each particle. k _hat is calculated (step S131). The average value x k _hat represents the state vector estimate obtained by the ensemble Kalman filter and is calculated by the following equation.

[0153]

number

[0154] The estimated value obtained by Eq. 38 (average value of each particle x k The estimated value of the temperature of each region and the estimated value of the short-circuit resistance are included in the estimated value of the short-circuit resistance. The calculation unit 11 estimates the presence or absence of an internal short circuit in the energy storage element 100 based on the estimated value of the short-circuit resistance. For example, the calculation unit 11 determines whether or not the estimated value of the short-circuit resistance is less than a threshold value (step S132). The threshold value is set arbitrarily.

[0155] If the estimated value of the short-circuit resistance is not less than the threshold value (S132: NO), it is estimated that no internal short circuit has occurred in the energy storage element 100. If it is estimated that no internal short circuit has occurred, the calculation unit 11 returns the process to step S122 and executes the calculation in the next time step.

[0156] If the estimated value of the short-circuit resistance is less than the threshold value (S132: YES), it is estimated that an internal short circuit has occurred in the energy storage element 100. If it is estimated that an internal short circuit has occurred, the calculation unit 11 notifies the occurrence of an internal short circuit (step S133). For example, the calculation unit 11 generates text information indicating that an internal short circuit has occurred, and outputs the text information to the display device 20 from the output unit 14, thereby causing the display device 20 to display the text information. Alternatively, the calculation unit 11 may notify a terminal device (not shown) of the text information indicating that an internal short circuit has occurred from the output unit 14. Furthermore, the calculation unit 11 may urge the user to stop using or replace the energy storage element 100, or may ask the user to decide whether to stop using or replace the energy storage element 100.

[0157] The detection device 10 in the third embodiment estimates the short-circuit resistance by using an ensemble Kalman filter. The ensemble Kalman filter is a filter method targeted at state space models having nonlinearity and non-Gaussianity, and can be targeted at more general state space models. The ensemble Kalman filter has a relatively simple algorithm and can be easily implemented in the detection device 10.

[0158] (Embodiment 4) In the fourth embodiment, a state estimation algorithm using an extended Kalman filter will be described. That is, the detection device 10 in the fourth embodiment uses an extended Kalman filter to sequentially calculate time updates of a time series model represented by a state equation of Expression 15 and an observation equation of Expression 16, and calculates an internal resistance R s The detection device 10 calculates the internal resistance R s Based on this, an internal short circuit in the energy storage element 100 is detected.

[0159] FIG. 13 is a flow chart for explaining the procedure for detecting an internal short circuit in the fourth embodiment. The calculation unit 11 of the detection device 10 provides an initial value of k=1 (step S141). The calculation unit 11 provides the environmental temperature as the initial value of the temperature, and provides a tentative value set in advance as the initial value of the short circuit resistance. The disturbance term v in the state equation is k and the disturbance term w in the observation equation k The variance of each is Q k and R k Assume that the initial variance-covariance matrix P is

[0160] The calculation unit 11 calculates the prior state estimate x - k+1 _hat is calculated by the following formula (step S142).

[0161]

number

[0162] The calculation unit 11 derives the Jacobian matrix of the nonlinear transformation f by the following procedure (step S143). For example, for a three-component vector expressed by Expression 40, when the nonlinear transformation f is expressed as Expression 41, the Jacobian is calculated by Expression 42. The calculation unit 11 may derive the Jacobian in advance and store it in the storage unit 12.

[0163]

number

[0164]

number

[0165]

number

[0166] The calculation unit 11 calculates the prior error covariance matrix P - k+1is calculated by the following equation (step S144). Here, the state transition matrix A k is expressed by the formula 44.

[0167]

number

[0168]

number

[0169] The calculation unit 11 calculates the Kalman gain g k (Step S145). The Kalman gain g k is represented by the number 45.

[0170]

number

[0171] The calculation unit 11 acquires the sensor output of the temperature sensor 250 through the input unit 13 (step S146). The acquired sensor output of the temperature sensor 250 is the observed value y k Gives.

[0172] The calculation unit 11 calculates the ex-post state estimate x k+1 _hat, and the posterior error covariance matrix P k is calculated by the following formula (step S147).

[0173]

number

[0174] The estimate obtained by Equation 46 (posterior state estimate x k+1The estimated value of the temperature of each region and the estimated value of the short-circuit resistance are included in the estimated value of the short-circuit resistance. The calculation unit 11 estimates the presence or absence of an internal short circuit in the energy storage element 100 based on the estimated value of the short-circuit resistance. For example, the calculation unit 11 determines whether or not the estimated value of the short-circuit resistance is less than a threshold value (step S148). The threshold value is set arbitrarily.

[0175] If the estimated value of the short-circuit resistance is not less than the threshold value (S148: NO), it is estimated that no internal short circuit has occurred in the energy storage element 100. If it is estimated that no internal short circuit has occurred, the calculation unit 11 returns the process to step S142 and executes the calculation in the next time step.

[0176] If the estimated value of the short-circuit resistance is less than the threshold value (S148: YES), it is estimated that an internal short circuit has occurred in the energy storage element 100. If it is estimated that an internal short circuit has occurred, the calculation unit 11 notifies the occurrence of an internal short circuit (step S149). For example, the calculation unit 11 generates text information indicating that an internal short circuit has occurred, and outputs the text information to the display device 20 from the output unit 14, thereby causing the display device 20 to display the text information. Alternatively, the calculation unit 11 may notify a terminal device (not shown) of the text information indicating that an internal short circuit has occurred from the output unit 14. Furthermore, the calculation unit 11 may urge the user to stop using or replace the energy storage element 100, or may ask the user to decide whether to stop using or replace the energy storage element 100.

[0177] The detection device 10 in the fourth embodiment estimates the short-circuit resistance by using an extended Kalman filter. The extended Kalman filter is a method that enables the application of a Kalman filter by linearly approximating a nonlinear model near a representative value such as an average value. The extended Kalman filter has a small calculation load and can be realized by an inexpensive device.

[0178] (Embodiment 5) In the fifth embodiment, a state estimation algorithm using an unscented Kalman filter will be described. That is, the detection device 10 in the fifth embodiment uses an unscented Kalman filter to sequentially calculate time updates of a time series model represented by a state equation of Expression 15 and an observation equation of Expression 16, and calculates an internal resistance Rs to obtain. The detection device 10 detects an internal short circuit of the energy storage element 100 based on the obtained internal resistance R s .

[0179] FIG. 14 is a flowchart for explaining the internal short circuit detection procedure in Embodiment 5. The arithmetic unit 11 of the detection device 10 gives an initial value of k = 1 (step S161). The arithmetic unit 11 may give the ambient temperature as the initial value of the temperature and a preset provisional value as the initial value of the short-circuit resistance. The disturbance term v k in the state equation and the disturbance term w k in the observation equation k are respectively set to Q k and R

[0180] The arithmetic unit 11 uses the estimated value x - k obtained at a certain calculation step and the covariance matrix P k to generate a calculation point called a sigma point (step S162). When the generated (2n + 1) sigma points are numbered as in Equation 47, the j-th (where j is an integer satisfying -n ≦ j ≦ n) sigma point is represented as in Equation 48.

[0181]

Equation

[0182]

Equation

[0183] However, sig(j) is a function that gives -1 when j < 0, 0 when j = 0, and +1 when 0 < j. κ is a positive adjustment parameter.

[0184] The weight w j of each sigma point j is set to w

[0185] The calculation unit 11 updates the states, a priori state estimates, and a priori error covariance matrix of all sigma points as follows (step S163).

[0186]

number

[0187] Having updated the a priori state estimate and the a priori error covariance matrix, the calculation unit 11 recalculates the sigma point by the following equation (step S164).

[0188]

number

[0189] The calculation unit 11 updates the observed sigma point according to the following equation (step S165).

[0190]

number

[0191] The calculation unit 11 calculates the prior observation estimate y - k+1 _hat is calculated by the following formula (step S166).

[0192]

number

[0193] The calculation unit 11 calculates the covariance matrix P - yy,k+1 is calculated by the following formula (step S167).

[0194]

number

[0195] The calculation unit 11 calculates the covariance matrix P- xy,k+1 is calculated by the following formula (step S168).

[0196]

number

[0197] The calculation unit 11 calculates the Kalman gain g k is calculated by the following formula (step S169).

[0198]

number

[0199] The calculation unit 11 acquires the sensor output of the temperature sensor 250 through the input unit 13 (step S170). The acquired sensor output of the temperature sensor 250 is the observed value y k+1 Gives.

[0200] The calculation unit 11 calculates the Kalman gain g k Let y be the observed value k+1 and the prior observation estimate y - k+1 _hat is multiplied by the difference to perform state estimation at time step k+1 (step S171).

[0201]

number

[0202] The calculation unit 11 calculates the covariance matrix P k+1 is calculated by the following formula (step S172).

[0203]

number

[0204] The posterior observation estimate (x k+1The estimated value of the temperature of each region and the estimated value of the short-circuit resistance are included in the estimated value of the short-circuit resistance. The calculation unit 11 estimates the presence or absence of an internal short circuit in the energy storage element 100 based on the estimated value of the short-circuit resistance. For example, the calculation unit 11 determines whether or not the estimated value of the short-circuit resistance is less than a threshold value (step S173). The threshold value is set arbitrarily.

[0205] If the estimated value of the short-circuit resistance is not less than the threshold value (S173: NO), it is estimated that no internal short circuit has occurred in the energy storage element 100. If it is estimated that no internal short circuit has occurred, the calculation unit 11 returns the process to step S162 and executes the calculation in the next time step.

[0206] If the estimated value of the short-circuit resistance is less than the threshold value (S173: YES), it is estimated that an internal short circuit has occurred in the energy storage element 100. If it is estimated that an internal short circuit has occurred, the calculation unit 11 notifies the occurrence of an internal short circuit (step S174). For example, the calculation unit 11 generates text information indicating that an internal short circuit has occurred, and outputs the text information to the display device 20 from the output unit 14, thereby causing the display device 20 to display the text information. Alternatively, the calculation unit 11 may notify a terminal device (not shown) of the text information indicating that an internal short circuit has occurred from the output unit 14. Furthermore, the calculation unit 11 may urge the user to stop using or replace the energy storage element 100, or may ask the user to decide whether to stop using or replace the energy storage element 100.

[0207] The detection device 10 in the fifth embodiment estimates the short-circuit resistance by using an unscented Kalman filter. The unscented Kalman filter sets multiple sample points called sigma points around the mean value, and estimates the covariance matrix based on the statistical properties of these points. The unscented Kalman filter performs better than the extended Kalman filter in problems with strong nonlinearity.

[0208] (Embodiment 6) In the sixth embodiment, the detection device 10 includes a short-circuit resistor R s A configuration for detecting a sign of an internal short circuit based on the above will be described.

[0209] 15 is a flowchart illustrating a procedure for detecting a sign of an internal short circuit. The calculation unit 11 of the detection device 10 calculates the short-circuit resistance R s is sequentially estimated (step S201).

[0210] The calculation unit 11 calculates the estimated short-circuit resistance R s It is determined whether or not the short circuit resistance R has decreased by a predetermined percentage from the reference value (step S202). s The average value of the short-circuit resistance R s If a sign of an internal short circuit is detected when the voltage drops by 10% or more from a reference value, the threshold value is set to 10%.

[0211] The calculation unit 11 calculates the estimated short-circuit resistance R s If the short-circuit resistance R s We will continue to estimate.

[0212] The calculation unit 11 calculates the estimated short-circuit resistance R s has decreased by a predetermined percentage from the reference value (S202: YES), it is estimated that a sign of an internal short circuit has occurred. When it is determined that a sign of an internal short circuit has occurred, the calculation unit 11 notifies the user of the sign of an internal short circuit (step S203). For example, the calculation unit 11 generates text information indicating that a sign of an internal short circuit has been detected, and outputs the text information to the display device 20 from the output unit 14, thereby causing the display device 20 to display the text information. Alternatively, the calculation unit 11 may notify a terminal device (not shown) of the text information indicating that a sign of an internal short circuit has been detected from the output unit 14. Furthermore, the calculation unit 11 may urge the user to stop using or replace the energy storage element 100, or may ask the user to decide whether to stop using or replace the energy storage element 100.

[0213] In the sixth embodiment, the estimated internal resistance R s The calculation unit 11 detects a sign of an internal short circuit by determining whether the estimated internal resistance Rs Alternatively, a sign of an internal short circuit may be detected based on the criterion of whether or not the voltage drops a set number of times (for example, five times) in succession.

[0214] In the first to sixth embodiments, the internal short circuit, including the sign of the short circuit, is detected based on the sensor output of the temperature sensor 250 that measures the temperature of the conductive tab. However, when a large current is output from the energy storage element 100, such as when a motor sports car is running or heavy machinery is used with a large torque, the conductive tab may reach a high temperature. In this case, the conductive tab reaches a high temperature, but this is within the range of normal use and is not an abnormality such as an internal short circuit. In order to distinguish between a case in which the conductive tab reaches a high temperature due to normal use and a case in which the conductive tab reaches a high temperature due to an internal short circuit, a heat transfer calculation based on the current flowing through the energy storage element 100 may be performed at the same time. The detection device 10 compares the temperature of the conductive tab measured by the temperature sensor 250 with the temperature of the conductive tab estimated from the current of the energy storage element 100, and if the two values ​​are close, it can be determined that the temperature rise is not due to an internal short circuit but is due to normal use. On the other hand, if a temperature rise that cannot be caused by the current flowing through the energy storage element 100 is measured, the detection device 10 may determine that an internal short circuit may have occurred.

[0215] (Embodiment 7) In the seventh embodiment, a configuration will be described in which, when an internal short circuit in energy storage element 100 is detected, a current path between electrode terminal 310 and a conductive tab (positive electrode tab 211 or negative electrode tab 221) is cut off.

[0216] The energy storage element 100 in embodiment 7 is equipped with a circuit breaker that cuts off the current path between the electrode terminal 310 and the conductive tab (positive electrode tab 211 or negative electrode tab 221) when an internal short circuit of the energy storage element 100 is detected by the detection device 10.

[0217] FIG. 16 is a partial cross-sectional view of the energy storage device 100 in the seventh embodiment, and FIG. 17 is a perspective view showing an example of mounting a circuit breaker. The energy storage device 100 includes a control board 150, a control circuit 151, and a semiconductor switching element 152 (hereinafter referred to as FET 152) in addition to the configuration described in the first embodiment. These are mounted, for example, in a space provided between the cover 112 of the energy storage device 100 and the current collector 140. In the seventh embodiment, the current collector 140 is divided into a first current collector 140a and a second current collector 140b. The first current collector 140a and the second current collector 140b are arranged with a gap provided therebetween. A positive electrode tab 211 is connected to the first current collector 140a, and a terminal electrode 310 is connected to the second current collector 140b.

[0218] The control board 150 is provided on the first current collector 140a and the second current collector 140b. The control board 150 is provided with rectangular cutouts 150a and 150b. The control circuit 151 is mounted on the control board 150. The FET 152 is mounted on an exposed surface of the first current collector 140a exposed from the cutout 150a.

[0219] The control circuit 151 acquires a detection result from the above-mentioned detection device 10, and turns on / off the FET 152 in accordance with the acquired detection result. In the seventh embodiment, the control circuit 151 and the detection device 10 are separate entities for convenience. Alternatively, the control circuit 151 and the detection device 10 may be integrated.

[0220] The FET 152 is, for example, a power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) for switching. A gate terminal 152G of the FET 152 is connected to the control circuit 151 via a printed wiring (not shown) formed on the control board 150. A drain terminal 152D is connected to an exposed surface of the first current collector 140a exposed from the notch 150a. A source terminal 152S is connected to an exposed surface of the second current collector 140b exposed from the notch 150b of the control board 150 across the gap between the first current collector 140a and the second current collector 140b.

[0221] The control circuit 151 can connect the drain terminal 152D and the source terminal 152S by applying a predetermined voltage (gate voltage) to the gate terminal 152G of the FET 152. As a result, the current path between the electrode terminal 310 and the positive electrode tab 211 is connected. On the other hand, the control circuit 151 can cut off the connection between the drain terminal 152D and the source terminal 152S by setting the gate voltage to zero. As a result, the current path between the electrode terminal 310 and the positive electrode tab 211 is cut off.

[0222] In the seventh embodiment, the FET 152 is disposed in the current path between the electrode terminal 310 and the positive electrode tab 211. Alternatively, the FET 152 may be disposed in the current path between the electrode terminal 320 and the negative electrode tab 221.

[0223] For the sake of simplicity, the seventh embodiment has been described with respect to a configuration in which only one FET 152 is implemented. Alternatively, the energy storage element 100 may further include an FET 152 in which the drain terminal 152D is connected to the second current collector 140b and the source terminal 152S is connected to the first current collector 140a.

[0224] In the seventh embodiment, the energy storage element 100 is described as having a FET 152 as a circuit breaker that cuts off the current path between the electrode terminal 310 and the conductive tab (positive electrode tab 211 or negative electrode tab 221). Alternatively, any circuit breaker may be used, such as a mechanical switch that is turned on / off by the control circuit 151, a switch using a bimetal that is deformed by being heated by the control circuit 151, or a fuse that is melted by being heated by the control circuit 151. In addition, when the energy storage element 100 includes a plurality of electrode bodies 200, the control circuit 151 may cut off only the current path leading to the electrode body 200 in which an internal short circuit has occurred.

[0225] 18 is a flowchart illustrating the procedure of the process executed by the control circuit 151. The control circuit 151 acquires the detection result from the detection device 10, and determines whether or not an internal short circuit has occurred in the energy storage element 100 (step S301).

[0226] When the control circuit 151 determines that no internal short circuit has occurred in the energy storage element 100 (S301: NO), it maintains the on state of the FET 152 (step S302), and returns the process to step S301.

[0227] When the control circuit 151 determines that an internal short circuit has occurred in the energy storage element 100 (S301: YES), the control circuit 151 turns off the FET 152 to cut off the current path between the electrode terminal 310 and the positive electrode tab 211 (step S303).

[0228] As described above, in embodiment 7, when an internal short circuit of the energy storage element 100 is detected by the detection device 10, the control circuit 151 cuts off the current path between the electrode terminal 310 and the conductive tab (positive electrode tab 211 or negative electrode tab 221), thereby preventing the energy storage element 100 from becoming too hot.

[0229] In the seventh embodiment, a configuration in which the current path is interrupted by using the FET 152 has been described. Alternatively, a semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor), a thyristor, or a bipolar transistor may be used. Also, a bimetal may be used for the conductive tab, and the conductive tab may be distorted and cut off due to an increase in temperature. Furthermore, a configuration in which the current path is interrupted by removing the constraint of a mechanical spring may be used. Furthermore, a configuration in which the current path is interrupted by melting may be used.

[0230] In the seventh embodiment, when the detection device 10 detects an internal short circuit of the energy storage element 100, the control circuit 151 is configured to cut off the current path. Alternatively, when the detection device 10 detects a sign of an internal short circuit of the energy storage element 100, the control circuit 151 may cut off the current path. Since cutting off the current path may cause an operating device or a traveling vehicle to suddenly stop, the control circuit 151 may cut off the current path after confirming that the device or vehicle in which the energy storage element 100 is mounted has stopped.

[0231] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims.

[0232] For example, in the first to seventh embodiments, the detection method of the internal short circuit has been described using the energy storage element 100 including the laminated electrode body 200 as an example, but the detection target of the internal short circuit may be an energy storage element including a wound electrode body. However, in the laminated electrode body 200, the positive electrode plates (or the negative electrode plates) are electrically connected to each other only via the positive electrode tab 211 (or the negative electrode tab 221), whereas in the wound electrode body, the positive electrode plates (or the negative electrode plates) are connected to each other not only via the tab but also via the winding part. Therefore, in the wound electrode body, even if the conductive tab is cut, the short circuit continues through the winding part. The effect of the present application is more effectively exerted in the energy storage element 100 including the laminated electrode body 200 than in the energy storage element including the wound electrode body.

[0233] The energy storage element in the embodiment may be a laminated type energy storage element. Fig. 19 is an external perspective view showing a laminated type energy storage element 500, and Fig. 20 is an exploded perspective view showing the laminated type energy storage element 500. The energy storage element 500 includes an exterior body 510 made of a laminate film, and a positive electrode lead terminal 520 and a negative electrode lead terminal 530 that protrude outward from both ends in the longitudinal direction of the energy storage element 500. A power generation element 540 and an electrolyte (not shown) are stored inside the exterior body 1. The power generation element 540 shown as an example in Fig. 20 has a structure in which strip-shaped positive and negative electrodes are wound into an elongated cylindrical shape.

[0234] The exterior body 510 is formed into a cylindrical shape by stacking two laminate films facing each other and welding their ends. The welding parts at both ends of the energy storage element 500 are welded while sandwiching a positive electrode lead terminal 520 and a negative electrode lead terminal 530, respectively. The exterior body 510 has a laminate structure in which, for example, a PE (polyethylene) welding layer, a PET (polyethylene terephthalate) layer, an aluminum layer, a PET layer, and a PE layer are laminated in this order.

[0235] The positive electrode lead terminal 520 is joined to the positive electrode of the power generating element 540 inside the exterior body 510. The positive electrode lead terminal 520 is made of, for example, a clad material (laminate) in which an aluminum layer and a titanium layer are roll-bonded.

[0236] The negative electrode lead terminal 530 is joined to the negative electrode of the power generating element 540 inside the exterior body 510. The negative electrode lead terminal 530 is formed of, for example, a laminate including a copper layer and titanium layers provided on both sides of the copper layer.

[0237] In the above-described energy storage element 500, the temperature sensor 250 is attached to the positive electrode lead terminal 520 (or the negative electrode lead terminal). The detection device 10 may acquire a sensor output of the temperature sensor 250 and detect an internal short circuit of the energy storage element 500 based on the acquired sensor output. The method of detecting an internal short circuit is similar to the detection methods described in the first to sixth embodiments. As in the seventh embodiment, the energy storage element may include a circuit breaker that cuts off a current path via the positive electrode lead terminal 520 (or the negative electrode lead terminal 530) when an internal short circuit of the energy storage element 500 is detected. [Explanation of symbols]

[0238] 10. Detection Device 11 Arithmetic section 12 Storage section 13 Input section 14 Output section 100 Energy storage element 110 Container 150 Control Board 151 Control circuit 152 Semiconductor switching element 200 Electrode body 210 Positive electrode plate 211 Positive electrode tab 220 Negative plate 221 Negative electrode tab 250 Temperature Sensor 230 Separator 310 Electrode terminal 320 electrode terminal PG state estimation program MD1,MD2 Thermal circuit model

Claims

1. a detection unit that detects an internal short circuit in the electrode body based on the short circuit resistance estimated by the observer for an energy storage element that includes an electrode terminal and an electrode body having a conductive tab, the electrode body being connected to the electrode terminal via the conductive tab, the detection unit comprising: an observer that estimates a short circuit resistance of an internal short circuit in the electrode body based on a sensor output from a temperature sensor that measures the temperature of the conductive tab, the detection unit detecting an internal short circuit in the electrode body based on the short circuit resistance estimated by the observer; a cut-off section that cuts off a current path between the electrode terminal and the electrode body in response to a detection result from the detection section; A shutoff device comprising:

2. The detection unit estimates a short-circuit resistance of the internal short circuit by using a state estimation algorithm based on the sensor output and a thermal circuit model that simulates a thermal phenomenon of the power storage element. The shutoff device according to claim 1 .

3. The thermal circuit model includes the electrode body, the conductive tab, and the short circuit portion as nodes, and includes parameters including the temperature and heat capacity at each node, and the thermal resistance between the nodes. The shutoff device according to claim 2.

4. The state estimation algorithm comprises: Using a state equation expressing the time transition of state variables including the temperature and short circuit resistance of each node, the time transition of each state variable is calculated; calculating a likelihood of a state estimation using an observation equation describing a relationship between the state variables and an observation amount including an observation temperature by the temperature sensor; Update the estimates of the state variables according to the likelihood of the state estimate. The shutoff device of claim 3 , further comprising:

5. The state estimation algorithm includes a particle filter, an ensemble Kalman filter, an extended Kalman filter, or an unscented Kalman filter. The interrupter according to any one of claims 2 to 4.

6. The electrode assembly is a laminated electrode assembly. A shutoff device according to any one of claims 1 to 5.

7. An electric storage element comprising an electrode terminal and an electrode body having a conductive tab, the electrode body being connected to the electrode terminal via the conductive tab, a temperature sensor for measuring a temperature of the conductive tab; a detection unit including an observer that estimates a short-circuit resistance of an internal short circuit in the electrode body based on a sensor output from the temperature sensor, and detects an internal short circuit in the electrode body based on the short-circuit resistance estimated by the observer; a cut-off unit that cuts off a current path between the electrode terminal and the electrode body in response to a detection result from the detection unit; A storage element comprising:

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