Protection device, mobile body, uninterruptible power supply system, solar power generation system, and protection method for power storage element

Abstract

To protect a power storage device by interrupting current in response to intermittent overcurrent conditions.SOLUTION: A protection device 120 for a power storage element 62 includes a current interruption device 53 that interrupts current flowing through the power storage element 62 and a control unit 130. The device is configured with multiple conditions having different current thresholds and cumulative thresholds. The control unit 130 calculates a cumulative value N representing the total time during which the current exceeds any of the current thresholds Is. When the calculated cumulative value N exceeds a corresponding cumulative threshold Ns associated with the current threshold Is, the control unit executes a current interruption process S150 to interrupt the current.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a technique for protecting an energy storage element from an overcurrent. [Background technology]

[0002] During assembly work, etc., terminals of an electric storage device may be short-circuited by a tool. The electric storage device is equipped with a current interruption device such as a relay or FET, which cuts off the current when a short circuit occurs, thereby protecting the components that make up the electric storage device. Patent Document 1 listed below describes that the current is cut off when the current exceeds a current threshold continuously for a period longer than a predetermined time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2015 / 182515 publication Summary of the Invention [Problem to be solved by the invention]

[0004] When determining whether to cut off the current based on the duration of continuous flow of a current above the current threshold, it may not be possible to cut off discontinuous overcurrents in which the current temporarily falls below the current threshold. If there is only one current cutoff condition, the current can only be cut off under that one condition, which may result in insufficient protection of the storage element.

[0005] An object of the present invention is to protect a power storage device by interrupting current in the event of a discontinuous overcurrent. [Means for solving the problem]

[0006] A protection device for a storage element according to one embodiment of the present invention comprises a current interruption device that interrupts the current of the storage element, and a control unit, and has a plurality of conditions with different current thresholds and cumulative thresholds, wherein the control unit calculates the cumulative value of the time during which the current exceeds one of the current thresholds, and when the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, executes a current interruption process to interrupt the current. Another aspect of the present invention provides a protection device for a storage element, comprising a current interruption device that interrupts the current of the storage element, a control unit, and a communication unit, and has a plurality of conditions with different current thresholds and cumulative thresholds, wherein the control unit calculates the cumulative value of the time during which the current exceeds one of the current thresholds, and when the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, causes the communication unit to send an alarm signal.

[0007] The present technology can be applied to a protection method for a storage element, a protection program, and a recording medium on which the protection program is recorded. [Effects of the Invention]

[0008] According to the above aspect, it is possible to protect the storage element by cutting off the current in the event of a discontinuous overcurrent. [Brief explanation of the drawings]

[0009] [Figure 1] Exploded perspective view of the battery [Figure 2] Plan view of secondary battery [Figure 3] Cross section of line AA in Figure 2 [Figure 4] Side view of the vehicle [Figure 5] Block diagram showing the electrical configuration of the battery [Figure 6] Monitoring process flowchart [Figure 7] Protection process flowchart [Figure 8] Diagram showing overcurrent waveform and count value [Figure 9] Diagram showing overcurrent waveform and count value [Figure 10] Diagram of current interruption conditions [Figure 11] Protection process flowchart [Figure 12] Cumulative time diagram [Figure 13] Diagram showing overcurrent waveform and cumulative time [Figure 14] Diagram of current interruption conditions [Figure 15] Block diagram showing the electrical configuration of the battery DETAILED DESCRIPTION OF THE INVENTION

[0010] The protection device for a storage element includes a current interruption device that interrupts the current of the storage element, and a control unit, and has multiple conditions with different current thresholds and cumulative thresholds.The control unit calculates the cumulative value of the time during which the current exceeds one of the current thresholds, and if the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, executes a current interruption process to interrupt the current.

[0011] If the cumulative value of the time during which the current threshold is exceeded exceeds the cumulative threshold, current cutoff processing is executed, thereby protecting the storage element from discontinuous overcurrent. By preparing multiple current cutoff conditions with different current thresholds and cumulative thresholds, the number of combinations of current thresholds and cumulative thresholds that can cut off the current increases compared to when there is only one condition. Therefore, the protection performance of the storage element against overcurrent can be improved compared to when there is only one condition. The control unit may calculate, for each condition, a cumulative value of the time during which the current exceeds the current threshold, and if the calculated cumulative value exceeds the cumulative threshold associated with the current threshold under any condition, execute a current cut-off process to cut off the current. Since the current cut-off process is executed when the cumulative threshold is exceeded under any one of a plurality of conditions, it is possible to protect the energy storage element from overcurrents of different current values and durations.

[0012] The protection device for a storage element includes a current interruption device that interrupts the current of the storage element, a control unit, and a communication unit, and has multiple conditions with different current thresholds and cumulative thresholds.The control unit calculates the cumulative value of the time during which the current exceeds one of the current thresholds, and if the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, causes the communication unit to send an alarm signal. There are situations in which it is undesirable for devices (e.g., electronic and electrical devices mounted on a vehicle) to which the power storage device supplies power to have the current from the power storage device cut off, resulting in a power failure. Protecting machinery that requires the power from the power storage device, such as a vehicle, may take priority over protecting the power storage device. In such cases, instead of performing a current cutoff process when a cutoff condition is met, the control unit notifies devices outside the power storage device that the cutoff condition has been met, i.e., transmits an alarm signal. This enables the control unit to cooperate with devices outside the power storage device and determine whether to perform a current cutoff process based on the priority in an emergency or other situation. Devices outside the power storage device can receive the alarm signal from the power storage device and begin preparations for a current cutoff process or other problem-solving processes.

[0013] The current interruption device may be provided in a current path connecting the energy storage element and an external terminal, and the conditions may include at least a first condition for determining that a short circuit has occurred in the external terminal and a second condition for determining that a short circuit has occurred in a load connected to the external terminal. When a short circuit occurs between the external terminals or in the load, the current interruption device can interrupt the current to protect the energy storage element.

[0014] The control unit may count the time during which the current continuously exceeds the current threshold as the cumulative value, and when the current falls below the current threshold from a state where it exceeds the current threshold, may retain the cumulative value if the time during which it fell below the threshold is less than or equal to a reset time.

[0015] If the time that the current remains below the current threshold is equal to or shorter than the reset time, the accumulated value is maintained. In other words, the accumulated value is not reset, and if the accumulated value subsequently exceeds the accumulation threshold, a current cutoff process is executed. This makes it possible to protect the storage element from discontinuous overcurrent.

[0016] The control unit may calculate the cumulative value for each detection period, and execute the current interruption process if the cumulative value exceeds the cumulative threshold value.

[0017] If the accumulated value exceeds the accumulation threshold within the detection time, a current cutoff process is executed, thereby protecting the storage element from discontinuous overcurrent.

[0018] <Embodiment 1> 1. Battery 50 Description

[0019] As shown in FIG. 1, the battery 50 includes a battery pack 60, a circuit board unit 65, and a housing 71.

[0020] The container 71 includes a main body 73 and a lid 74 made of synthetic resin material. The main body 73 is cylindrical with a bottom. The main body 73 includes a bottom portion 75 and four side portions 76. The four side portions 76 form an upper opening 77 at the top end.

[0021] The housing 71 houses the battery pack 60 and the circuit board unit 65. The battery pack 60 has 12 secondary batteries 62. The 12 secondary batteries 62 are connected in three parallel connections and four in series. The circuit board unit 65 is disposed on top of the battery pack 60.

[0022] The lid 74 closes the upper opening 77 of the main body 73. An outer peripheral wall 78 is provided around the periphery of the lid 74. The lid 74 has a protruding portion 79 that is generally T-shaped in plan view. The positive electrode external terminal 51 is fixed to one corner of the front of the lid 74, and the negative electrode external terminal 52 is fixed to the other corner.

[0023] 2 and 3, the secondary battery 62 includes an electrode assembly 83 housed together with a non-aqueous electrolyte in a rectangular parallelepiped case 82. The secondary battery 62 is, for example, a lithium-ion secondary battery. The case 82 has a case body 84 and a lid 85 that closes the upper opening.

[0024] Although not shown in detail, the electrode body 83 is made up of a negative electrode element made of a copper foil substrate coated with an active material, and a positive electrode element made of an aluminum foil substrate coated with an active material, with a separator made of a porous resin film disposed between them. Both of these are strip-shaped, and are wound flat so that they can be housed in the case body 84, with the negative electrode element and the positive electrode element offset from each other on opposite sides in the width direction relative to the separator.

[0025] A positive electrode terminal 87 is connected to the positive electrode element via a positive electrode current collector 86, and a negative electrode terminal 89 is connected to the negative electrode element via a negative electrode current collector 88. The positive electrode current collector 86 and the negative electrode current collector 88 each comprise a flat base 90 and a leg 91 extending from the base 90. A through hole is formed in the base 90. The leg 91 is connected to the positive electrode element or the negative electrode element. The positive electrode terminal 87 and the negative electrode terminal 89 each comprise a terminal body 92 and a shaft 93 protruding downward from the center of the lower surface of the terminal body 92. Of these, the terminal body 92 and shaft 93 of the positive electrode terminal 87 are integrally molded from aluminum (a single material). In the negative electrode terminal 89, the terminal body 92 is made of aluminum, and the shaft 93 is made of copper, and these are assembled together. The terminal bodies 92 of the positive electrode terminal 87 and the negative electrode terminal 89 are disposed on both ends of the lid 85 via gaskets 94 made of an insulating material, and are exposed to the outside from the gaskets 94 .

[0026] The lid 85 has a pressure relief valve 95. As shown in Fig. 2, the pressure relief valve 95 is located between the positive electrode terminal 87 and the negative electrode terminal 89. The pressure relief valve 95 opens to reduce the internal pressure of the case 82 when the internal pressure of the case 82 exceeds a limit value.

[0027] As shown in Fig. 4, the battery 50 can be mounted on a vehicle 10 for use. The battery 50 may be used to start an engine 20 mounted on the vehicle 10. The vehicle 10 may be an automobile or a motorcycle.

[0028] 5 is a block diagram showing the electrical configuration of battery 50. Battery 50 includes battery pack 60, current detection resistor 54, current interruption device 53, voltage detection circuit 110, management unit 130, and temperature sensor 58 that detects the temperature of battery pack 60.

[0029] The battery pack 60 is composed of a plurality of secondary batteries 62. There are 12 secondary batteries 62, connected three in parallel and four in series. In FIG. 5, three secondary batteries 62 connected in parallel are represented by a single battery symbol. The secondary batteries 62 are an example of an "energy storage element." The battery 50 has a rated voltage of 12 V. A 12 V rated battery 50 tends to have a narrow gap between the positive external terminal 51 and the negative external terminal 52, and compared to larger energy storage devices, it is more susceptible to short circuits (dead shorts) between the terminals due to metal objects such as tools when installing the battery in a vehicle.

[0030] The battery pack 60, the current interruption device 53, and the current detection resistor 54 are connected in series via a power line 55P and a power line 55N. The power line 55P and the power line 55N are an example of a current path.

[0031] The power line 55P is a power line that connects the positive external terminal 51 and the positive electrode of the battery pack 60. The power line 55N is a power line that connects the negative external terminal 52 and the negative electrode of the battery pack 60.

[0032] The current interruption device 53 is located on the positive side of the battery pack 60 and is provided on the positive side power line 55P. The current interruption device 53 is a semiconductor switch such as an FET or a relay. By opening the current interruption device 53, the current of the battery 50 can be interrupted. The current interruption device 53 is normally controlled to be closed.

[0033] The current detection resistor 54 is located at the negative electrode of the battery pack 60 and is provided on the negative-side power line 55N. By detecting the voltage Vr across the current detection resistor 54, the current I of the battery pack 60 can be measured.

[0034] The voltage detection circuit 110 can detect the voltage V of each secondary battery 62 and the total voltage Vab of the battery pack 60.

[0035] The management unit 130 is mounted on the circuit board 100 and includes a CPU 131, a memory 133, and four counters 135. The management unit 130 performs monitoring processing of the battery 50 based on the outputs of the voltage detection circuit 1100, the current detection resistor 54, and the temperature sensor 58.

[0036] 6 is a flowchart of the monitoring process of the battery 50. The monitoring process of the battery 50 is made up of steps S10 to S30. The monitoring process of the battery 50 is always executed at a predetermined measurement cycle while the management unit 130 is running, regardless of whether the battery 50 is mounted on the vehicle 10 or not.

[0037] In S10, the management unit 130 measures the current I of the battery pack 60 based on the voltage Vr across the current detection resistor 54. In S20, the management unit 130 measures the voltage V of each secondary battery 62 based on the output of the voltage detection circuit 110, and in S30, measures the temperature of the battery pack 60 based on the output of the temperature sensor 58.

[0038] The management unit 130 operates using the battery pack 60 as a power source, and constantly monitors the state of the battery 50 based on the data of the current I, voltage V, and temperature measured at a predetermined measurement interval, unless there is an abnormality such as the total voltage Vab of the battery pack 60 falling below the operating voltage.

[0039] When the management unit 130 detects an abnormality in the battery 50, it issues a command to the current interruption device 53 to interrupt the current I and perform a protective operation for the battery 50. The current interruption device 53 and the management unit 130 constitute the protection device 120 for the battery 50. The management unit 130 is an example of a control unit.

[0040] 2. External short circuit and battery protection If a metal object, such as the tool 200, shorts the two external terminals 51 and 52 during assembly work, an overcurrent will flow through the battery pack 60. When an overcurrent flows, the battery pack 60 will generate abnormal heat. The overcurrent value during discharge due to an external short circuit is much larger than the current value during a charging abnormality. However, when starting the engine, for example, a very large current value is measured even during normal discharge. Therefore, during discharge, it is not easy to determine from the current value alone whether an abnormality such as an external short circuit has occurred or whether the power storage device is operating normally. A dead short caused by the tool 200 or the like may occur intermittently, such as when the tool 200 momentarily separates from the external terminals 51 and 52 and then reconnects them. Even if the dead short is momentarily released, the battery 50 does not immediately recover, and damage to the battery 50 remains, such as a significant drop in the state of charge (SOC).

[0041] 7 is a flowchart of the protection process for the battery 50. The protection process for the battery 50 is made up of steps S10 to S180. The protection process for the battery 50 is always executed while the management unit 130 is running, regardless of whether the battery 50 is mounted on the vehicle 10 or not.

[0042] In S100, the management unit 130 compares the current I measured in the monitoring process with a current threshold Is. The comparison process in S100 is executed every time a current is measured in the monitoring process if the current I is equal to or less than the current threshold Is (S100: NO). The current threshold Is is a threshold used to determine whether the current I is an overcurrent.

[0043] If an overcurrent exists (S100: YES), the process proceeds to S110. When the process proceeds to S110, the management unit 130 starts counting using the counter 135. The counter 135 is used to measure the cumulative time that the overcurrent has been flowing.

[0044] After counting starts, the process proceeds to S120. In S120, the management unit 130 compares the current I measured in the next measurement cycle of the monitoring process with the current threshold Is to determine whether the overcurrent continues.

[0045] If the overcurrent continues (S120: YES), the process proceeds to S 130. When the process proceeds to S 130, the management unit 130 increments the count value N of the counter 135 by "+1".

[0046] Thereafter, in S140, the management unit 130 compares the count value N with the accumulation threshold value Ns. If the count value N is smaller than the accumulation threshold value Ns (S140: NO), the process returns to S120. The accumulation threshold value Ns is a threshold value used to determine the accumulation of overcurrent.

[0047] After that, if the overcurrent continues to flow, the count value N is incremented by 1 at each measurement cycle of the monitoring process. The count value N is the cumulative value of the time during which the current I exceeds the current threshold Is.

[0048] When the count value N reaches the cumulative threshold value Ns, the determination process of S140 returns YES, and the process proceeds to S150. When the process proceeds to S150, the management unit 130 issues a command to the current interruption device 53 to interrupt the overcurrent (current interruption process).

[0049] If the overcurrent does not continue, that is, if the current I is lower than the current threshold Is (S120: NO), the process proceeds to S160.

[0050] In S160, the management unit 130 measures the time during which the current I is below the current threshold Is, and compares the measured time with the reset time TR.

[0051] If the time during which the current is below the current threshold Is is shorter than the reset time TR, the process proceeds to S170. When the process proceeds to S170, the management unit 130 holds the count value N.

[0052] Thereafter, the process proceeds to S140, and when an overcurrent is detected, the management unit 130 restarts counting by the counter 135, and the count value N is incremented from the held value.

[0053] On the other hand, if the time during which the current is below the current threshold Is is longer than the reset time TR, the process proceeds to S180. When the process proceeds to S180, the management unit 130 resets the count value N. As a result, the count value N returns to zero.

[0054] Figure 8 shows the waveform of an overcurrent and the transition of the count value N. The waveform of an overcurrent is a continuous waveform that always exceeds the current threshold Is. After time t1, when the overcurrent begins to flow, the count value N is cumulatively added up and increases in value, reaching the cumulative threshold Ns at time t2.

[0055] When the count value N reaches the cumulative threshold value Ns at time t2, the management unit 130 executes a current cutoff process (S150) to cut off the overcurrent. By cutting off the overcurrent, the battery 50 can be protected.

[0056] 9 is a diagram showing the current waveform of an overcurrent and the transition of the count value N. The overcurrent waveform is a discontinuous pulse waveform, and the current I is below the current threshold Is from t2 to t3 and from t4 to t5. 23 , period X 45 The length of the period is shorter than the reset time TR.

[0057] During the period from time t1 when the overcurrent starts to flow to time t2, the current I exceeds the current threshold Is, and the count value N is incremented each time S130 is executed, and increases over time.

[0058] Period X from time t2 to time t3 23 At this time, the current I falls below the current threshold Is, but the time is shorter than the reset time TR, so the count value N is not reset but is maintained.

[0059] Between time t3 and time t4, the current I exceeds the current threshold Is, so the count value N is incremented each time S130 is executed, and increases from the held value.

[0060] Period X from time t4 to time t5 45At this time, the current I falls below the current threshold Is, but the time is shorter than the reset time TR, so the count value N is not reset but is maintained.

[0061] After time t6, the current I exceeds the current threshold Is, so the count value N is incremented each time S130 is executed, and increases from the held value. Then, at time t6, the count value N reaches the cumulative threshold Ns.

[0062] When the count value N reaches the cumulative threshold value Ns at time t6, the management unit 130 executes a current cutoff process (S150) to cut off the overcurrent.

[0063] Even if the current I falls below the current threshold Is, the count value N is not reset but maintained as long as it is within the reset time TR. Therefore, even in the case of a discontinuous overcurrent in which there is a period in which the current I temporarily drops, the count value N can be prevented from being reset each time the current I falls below the current threshold Is, and the overcurrent can be cut off when the count value N reaches the cumulative threshold Ns.

[0064] Fig. 10 is a diagram showing current interruption conditions. The current interruption conditions consist of the current threshold Is, cumulative threshold Ns, and reset time TR. There are four current interruption conditions, conditions 1 to 4, each with a different current threshold Is and cumulative threshold Ns. The reset time TR is common to all conditions 1 to 4.

[0065] Current interruption condition 1 is a condition for determining that a short circuit has occurred between the two external terminals 51 and 52 (or a condition for interrupting an external short circuit), and current interruption conditions 2 to 4 are conditions for determining that a short circuit has occurred in the load connected to external terminal 51 and external terminal 52 (or a condition for interrupting a load short circuit). Current interruption condition 1 has a current threshold Is of 1450 A and a cumulative threshold Ns of 10 msec. Current interruption condition 1 has a larger current threshold Is and a shorter cumulative threshold Ns than current interruption conditions 2 to 4.

[0066] In the current interruption conditions 2 to 4, the magnitude of the short-circuit current differs depending on how the load is short-circuited, so the current threshold Is is set to three levels, and the smaller the current threshold Is, the longer the cumulative threshold Ns.

[0067] The management unit 130 uses four counters 135 to simultaneously perform the protection processes (S100 to S150) shown in Figure 7 for current interruption conditions 1 to 4, and when the count value N reaches the cumulative threshold value Ns under any of current interruption conditions 1 to 4, it executes the current interruption process of S150 to interrupt the overcurrent.

[0068] By preparing multiple current interruption conditions, the number of combinations of current threshold Is and cumulative threshold Ns increases compared to when there is only one condition. As a result, the current I can be interrupted in both the event of an external terminal short circuit and a load short circuit.

[0069] <Embodiment 2> 11 is a flowchart of the protection process for the battery 50. The protection process for the battery 50 is always executed while the management unit 130 is running, regardless of whether the battery 50 is mounted on the vehicle 10 or not. The management unit 130 compares the current I measured in the monitoring process with a current threshold Is (S200). The current threshold Is is a threshold for determining whether the current I is an overcurrent or not.

[0070] If an overcurrent occurs (S200: YES), the management unit 130 starts recording the current I (S210). The current I is recorded in the memory 133.

[0071] After starting the recording, the management unit 130 calculates (S220) the accumulated time Ta during which the overcurrent has flowed during the detection period W. The accumulated time Ta is the accumulated value of the time during the detection period W during which the current I has exceeded the current threshold Is.

[0072] As shown in FIG. 12, for example, if there are three periods in which the current I exceeds the current threshold Is during the detection period W, the total time of the three periods (Ta1+Ta2+Ta3) is the cumulative time Ta.

[0073] Thereafter, the management unit 130 determines whether the cumulative time Ta is zero (S230), and if the cumulative time Ta is not zero, determines whether it is equal to or greater than the cumulative threshold Ts (S240).

[0074] If the cumulative time Ta is zero (S230: YES), the management unit 130 ends recording of the current I (S260). If the cumulative time Ta is equal to or greater than the cumulative threshold Ts (S240: YES), the management unit 130 performs a current interruption process to interrupt the current I using the current interruption device 53 (S250).

[0075] If the cumulative time Ta is smaller than the cumulative threshold Ts (S240: NO), the process returns to S220, and the management unit 130 executes the processes of S220 to S240 for the next detection period W.

[0076] 13 is a diagram showing the current waveform of an overcurrent and the transition of accumulated time Ta. The overcurrent waveform is a discontinuous pulse waveform, and the current I is below the current threshold Is from t2 to t3 and from t4 to t5.

[0077] Recording of the current I begins at time t1 when the current I exceeds the current threshold Is. The management unit 130 calculates the cumulative time Ta for the detection period W1 and compares it with the current interruption value Ts. If the cumulative time Ta does not exceed the cumulative threshold Ts, the management unit 130 calculates the cumulative time Ta for the next detection period W2 and compares it with the cumulative threshold Ts.

[0078] The accumulated time Ta does not reach the accumulated threshold value Ts during the detection periods W1 to W8, and reaches the accumulated threshold value Ts during the detection period W9. Therefore, at time t6 when the detection period W9 has elapsed, the management unit 130 executes the current interruption process (S250), and the overcurrent is interrupted.

[0079] The detection periods W1 to W9 are successive and overlap one another, with a shift of period Y. This shortens the detection interval of the accumulated time Ta, allowing the current interruption process (S250) to be performed quickly when a short circuit occurs.

[0080] 14 is a diagram showing current interruption conditions. The current interruption conditions consist of the items of current threshold Is, cumulative threshold Ts, and detection time W. There are four types of current interruption conditions, 1 to 4, each with a different current threshold Is, cumulative threshold Ts, and detection time W.

[0081] Current interruption condition 1 is a first condition for interrupting a short circuit between two external terminals 51 and 52. Current interruption conditions 2 to 4 are second conditions for interrupting a short circuit in a load connected to external terminal 51 and external terminal 52.

[0082] The management unit 130 simultaneously performs the protection processes (S200 to S260) shown in FIG. 11 for current interruption conditions 1 to 4, and when the cumulative time Ta reaches the cumulative threshold Ts under any of the current interruption conditions, it executes the current interruption process of S250 to interrupt the overcurrent.

[0083] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0084] (1) In the above embodiment, a secondary battery 62 is given as an example of an electric storage element. The electric storage element is not limited to the secondary battery 62, but may be a capacitor. The secondary battery 62 is not limited to a lithium ion secondary battery, but may be another non-aqueous electrolyte secondary battery. A lead storage battery or the like may also be used. The electric storage element is not limited to a case where a plurality of electric storage elements are connected in series or in parallel, but may be connected in series or configured as a single cell.

[0085] (2) In the above embodiment, the battery 50 is for use in a vehicle. The use of the battery 50 is not limited to a specific use. The battery 50 may be used for various purposes, such as for mobile objects (vehicles, ships, AGVs, etc.) and industrial purposes (power storage devices for uninterruptible power supply systems and solar power generation systems).

[0086] (3) In the above embodiment, the management unit 130 is provided inside the battery 50. The battery 50 is only required to include at least instruments such as the current detection resistor 54 and the voltage detection circuit 110 and the current interruption device 53, and the management unit 130 may be located outside the battery 50.

[0087] (4) In the above embodiment, the current interruption device 53 is arranged on the positive power line 55P, and the current detection resistor 54 is arranged on the negative power line 55N. The configuration may be reversed, and the current detection resistor 53 may be arranged on the positive power line 55P, and the current detection resistor 54 may be arranged on the negative power line 55N.

[0088] (5) In the above embodiment, the protection processes (S200 to S260) are performed simultaneously for current interruption conditions 1 to 4. When the cumulative time Ta reaches the cumulative threshold Ts under any of the current interruption conditions, the current interruption process is performed to interrupt the overcurrent. Alternatively, the protection processes (S200 to S260) may be performed for any one of the four current interruption conditions 1 to 4. When the count value N reaches the cumulative threshold Ns, the current interruption process is performed to interrupt the overcurrent. For example, if an external short circuit is expected to occur easily, the protection processes (S200 to S260) may be performed only for current interruption condition 1. When the count value N reaches the cumulative threshold Ns, the current interruption process is performed to interrupt the overcurrent. When selecting a current interruption condition, it is advisable to select a current interruption condition corresponding to a short circuit that is likely to occur. The selection of a current interruption condition is not limited to one, and two current interruption conditions may be performed. In other words, it is sufficient to select at least one condition. The management unit 130 may calculate the cumulative value of the time during which the current I exceeds any one of the current thresholds Is, and may execute a current cut-off process when the calculated cumulative value exceeds the cumulative threshold associated with the current threshold Is.

[0089] (6) In the above embodiment, the control unit calculates the cumulative value of the time during which the current exceeds one of the current thresholds, and when the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, executes a current cut-off process to cut off the current. Alternatively, the control unit may calculate the cumulative value of the time during which the current exceeds one of the current thresholds, and when the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, cause the communication unit to send an alarm signal. 15, the protection device 120 may include a communication unit 137 controlled by the management unit 130. The housing 71 may include a communication connector 138, for example, on its lid 74. The communication unit 137 may be connected via the communication connector 138 to be able to communicate with a controller outside the battery, such as an ECU (Electronic Control Unit) of the vehicle. Instead of executing the current cut-off process when the cut-off condition is met, the management unit 130 notifies the ECU outside the battery that the cut-off condition is met via the communication unit 137, i.e., sends an alarm signal, and determines whether to execute the current cut-off process in cooperation with the ECU. Upon receiving the alarm signal, the ECU can proceed with preparations for the current cut-off process, processing to avoid the current cut-off process, such as stopping the operation of some loads, or other problem-solving processing.

[0090] (7) The present technology can be applied to a protection program for a storage element. The protection estimation program for a storage element is a program that causes a computer to execute the following processes. The current interruption conditions for interrupting the current of the storage element include a plurality of conditions with different current thresholds and cumulative thresholds, and the control unit calculates a cumulative value of the time during which the current exceeds any one of the current thresholds, and when the calculated cumulative value exceeds the cumulative threshold associated with the current threshold, causes the program to execute a current interruption process to interrupt the current. The present technology can be applied to a recording medium on which the protection program for a storage element is recorded. An example of the computer is the management unit 130. An example of the storage element is the secondary battery 62. The protection program can be recorded on a recording medium such as a ROM. [Explanation of symbols]

[0091] 10 vehicles 50 Battery (energy storage device) 53 Current interrupter 54 Current detection resistor 60 battery packs 62 Secondary battery (energy storage element) 120 Protective devices 130 Management Department (Control Department) 131 CPU 133 memory 135 counters N count value (cumulative value) Ns cumulative threshold Is current threshold Ta: Accumulated time (accumulated value) Ts cumulative threshold

Claims

1. A protection device for a storage element, a current interruption device that interrupts the current of the storage element; a control unit, the control unit calculates a cumulative value of a time during which the current exceeds a current threshold, and when the calculated cumulative value exceeds a cumulative threshold associated with the current threshold, executes a current interruption process to interrupt the current; The control unit counts only the accumulated time during which an overcurrent in which the current continuously exceeds the current threshold is flowing as the accumulated value, and when the current falls below the current threshold from a state in which it exceeds the current threshold, does not reset the accumulated value if the time during which the current has fallen below the threshold is less than or equal to a reset time.

2. A protection device for a storage element, a current interruption device that interrupts the current of the storage element; A control unit; a communication unit, the control unit calculates a cumulative value of a time during which the current exceeds a current threshold, and when the calculated cumulative value exceeds a cumulative threshold associated with the current threshold, causes the communication unit to transmit an alarm signal; The control unit counts only the accumulated time during which an overcurrent in which the current continuously exceeds the current threshold is flowing as the accumulated value, and when the current falls below the current threshold from a state in which it exceeds the current threshold, does not reset the accumulated value if the time during which the current has fallen below the threshold is less than or equal to a reset time.

3. A storage element; A power storage device comprising: the protection device according to claim 1 or 2.

4. The power storage device according to claim 3, A storage device rated at 12V.

5. A method for protecting a storage element, comprising: the control unit calculates a cumulative value of the time during which the current exceeds a current threshold, and when the calculated cumulative value exceeds a cumulative threshold associated with the current threshold, executes a current interruption process to interrupt the current; The control unit counts only the accumulated time during which an overcurrent in which the current continuously exceeds the current threshold is flowing as the accumulated value, and when the current falls below the current threshold from a state in which it exceeds the current threshold, does not reset the accumulated value if the time during which it has fallen below the current threshold is equal to or shorter than a reset time.

6. A method for protecting a storage element, comprising: a control unit that calculates a cumulative value of a time during which the current exceeds a current threshold, and when the calculated cumulative value exceeds a cumulative threshold associated with the current threshold, causes the control unit to transmit an alarm signal; The control unit counts only the accumulated time during which an overcurrent in which the current continuously exceeds the current threshold is flowing as the accumulated value, and when the current falls below the current threshold from a state in which it exceeds the current threshold, does not reset the accumulated value if the time during which it has fallen below the current threshold is equal to or shorter than a reset time.

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