Control device, energy storage device, and voltage simulation method

Abstract

To suppress erroneous determination on whether or not discharge can be performed by a discharge pattern.SOLUTION: A management device 130 for periodically executing voltage simulation of a power storage device 50 includes an arithmetic part 131 and a storage part 132. The storage part 132 stores a discharge pattern P formed of time series data of discharge current. The discharge pattern P includes first time series data D1 and second time series data D2 of discharge current. The first time series data D1 is time series data for a prescribed time of discharge current, and the second time series data D2 is time series data of discharge current within a voltage simulation execution period of the power storage device. The arithmetic part 131 periodically executes voltage simulation for estimating a voltage change of the power storage device 50 when the power storage device is discharged by the discharge pattern P, and periodically determines whether or not the power storage device can be discharged by the discharge pattern P on the basis of a result of voltage simulation.SELECTED DRAWING: Figure 6B

Description

Technical Field

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[0001] The present invention relates to voltage simulation of a power storage device.

Background Art

[0002] Power storage devices are used in various applications, such as power sources for moving bodies represented by automobiles and power storage for solar power generation systems (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the functions of a power storage device is voltage simulation. Voltage simulation estimates the voltage change of the power storage device when discharging in a predetermined discharge pattern. For example, in the case of a power storage device for an automobile, the dischargeability according to the discharge pattern is determined using the result of voltage simulation.

[0005] By periodically executing voltage simulation, it is possible to periodically confirm whether discharge according to the discharge pattern is possible. Voltage simulation is not limited to automobiles and can also be applied to other applications such as power storage for solar power generation systems.

[0006] However, if the power storage device is discharging within the execution period of voltage simulation, there is a possibility of misjudging the dischargeability.

[0007] An object of the present invention is to suppress misjudgment of dischargeability according to a discharge pattern. [Means for solving the problem]

[0008] This section provides an overview of the control system. The control device is a device that periodically performs voltage simulations of the energy storage device. The control device includes a calculation unit and a memory unit. The voltage simulation of the energy storage device may be a simulation of the voltage of the external terminals, or a simulation of the voltage of the cells or battery packs.

[0009] The storage unit stores a discharge pattern consisting of time-series data of discharge current. The discharge pattern includes a first time-series data and a second time-series data of discharge current. The first time-series data is time-series data of discharge current for a predetermined period of time, and the second time-series data is time-series data of discharge current within the voltage simulation execution period of the energy storage device.

[0010] The calculation unit periodically performs a voltage simulation to estimate the voltage change of the energy storage device when the energy storage device discharges according to the discharge pattern, and periodically determines whether the energy storage device can discharge according to the discharge pattern based on the results of the voltage simulation.

[0011] This technology can be applied to voltage simulation methods and voltage simulation programs. [Effects of the Invention]

[0012] This technology can suppress misjudgments regarding the feasibility of discharge based on the discharge pattern. [Brief explanation of the drawing]

[0013] [Figure 1] Side view of a car [Figure 2] Battery disassembled perspective view [Figure 3] Plan view of a secondary battery cell [Figure 4] Cross-sectional view along line AA in Figure 3 [Figure 5] Block diagram showing the electrical configuration of the battery [Figure 6A] Waveform of the discharge pattern before improvement [Figure 6B] Waveform of the discharge pattern after improvement [Figure 7] Timeline of voltage simulation [Figure 8] Voltage estimation result by voltage simulation [Figure 9] Voltage estimation result by voltage simulation [Figure 10] Diagram showing input / output to the arithmetic unit [Figure 11] Diagram showing the execution period of voltage simulation [Figure 12A] Waveform of the first discharge pattern [Figure 12B] Waveform of the second discharge pattern [Figure 13] Flowchart of voltage simulation [Figure 14] Diagram showing input / output to the arithmetic unit

Mode for Carrying Out the Invention

[0014] The outline of the management device will be described. [[ID=4l]] (1) The management device according to an embodiment of the present invention is a device that periodically performs voltage simulation of a power storage device. The management device includes an arithmetic unit and a storage unit.

[0015] The storage unit stores a discharge pattern composed of time-series data of discharge current. The discharge pattern includes first time-series data and second time-series data of discharge current. The first time-series data is time-series data for a predetermined time of discharge current, and the second time-series data is time-series data of discharge current within the voltage simulation execution period of the power storage device.

[0016] The arithmetic unit periodically performs voltage simulation to estimate the voltage change of the power storage device when the power storage device discharges in the discharge pattern, and periodically determines whether the power storage device can discharge according to the discharge pattern based on the result of the voltage simulation.

[0017] According to the control device described in (1) above, the discharge pattern includes a second time series of data in addition to the first time series of data of the discharge current. Since the second time series of data is the time series of data of the discharge current within the voltage simulation execution cycle of the energy storage device, it becomes possible to perform a voltage simulation that takes into account the discharge within the execution cycle.

[0018] Therefore, it is possible to prevent the system from mistakenly determining that the energy storage device is capable of discharging according to the discharge pattern, even though, in reality, the device does not have the capacity to discharge according to the discharge pattern due to discharge within the execution cycle.

[0019] (2) In the control device described in (1) above, the execution period of the voltage simulation may be switchable. According to the control device described in (2) above, shortening the execution period shortens the period for determining whether discharge is possible or not, so that when the energy storage device transitions from a state where it can discharge to a state where it cannot, it can be detected early. Lengthening the execution period reduces the computational load on the calculation unit and saves energy.

[0020] (3) In the management device described in (2) above, the energy storage device may be for a vehicle. According to the management device described in (3) above, the calculation unit may perform a voltage simulation in the first cycle when the vehicle is in the first state, and perform a voltage simulation in the second cycle when the vehicle is in the second state. In this configuration, the accuracy of the discharge feasibility determination can be switched according to the state of the vehicle.

[0021] (4) In the control device described in (3) above, the first state is when the vehicle is running, the second state is when the vehicle is not running, and the second cycle may be longer than the first cycle. According to the control device described in (4) above, when the vehicle is running, the voltage simulation is performed in the first cycle (short cycle), so if the energy storage device reaches a state where it is unable to discharge according to the discharge pattern, it is possible to detect this early. On the other hand, when the vehicle is not running, the voltage simulation is performed in the second cycle (long cycle), so the power consumption of the control device can be reduced and energy can be saved.

[0022] (5) In the control device described in (3) or (4) above, the second time series data may vary depending on the state of the vehicle. With the control device described in (5) above, since the voltage simulation is performed using the second time series data corresponding to the state of the vehicle, the estimation error of the discharge current within the execution period of the voltage simulation can be suppressed. Therefore, a highly accurate voltage simulation can be performed.

[0023] (6) In the control device described in (5) above, the first state may be when the vehicle is running, and the second state may be when the vehicle is not running. The second time series data when the vehicle is not running may be smaller than the second time series data when the vehicle is running. According to the control device described in (5) above, the error in the discharge current (the error between the actual discharge current and the simulated discharge current) can be reduced by increasing the value of the second time series data when the vehicle is running and there is a lot of discharge, and decreasing the value of the second time series data when the vehicle is not running and there is a lot of discharge.

[0024] (7) In the management device described in any one of the above paragraphs (2) to (6), the storage unit may store a first discharge pattern having time-series data for the first period and a second discharge pattern having time-series data for the second period as the execution period of the voltage simulation. The calculation unit may, when the first period is selected, select the first discharge pattern and execute the voltage simulation, and when the second period is selected, select the second discharge pattern and execute the voltage simulation. According to the management device described in (7), since a discharge pattern is provided for each period, the accuracy of the voltage simulation is high regardless of the difference in period. Therefore, the accuracy of determining whether discharge is possible or not based on the discharge pattern can be further improved.

[0025] (8) In the management device described in any one of the above items (1) to (7), the calculation unit may estimate the voltage change of the energy storage device in the voltage simulation based on the State of Charge (SOC) of the energy storage device, the internal resistance of the cell, the discharge current, the temperature of the cell, and the charge / discharge history. According to the management device described in (8), since the voltage simulation takes into account the voltage change due to the change in SOC, as well as the voltage change due to internal resistance, temperature, and charge / discharge history, the accuracy of the voltage estimation and the accuracy of the determination of whether or not power can be supplied can be increased.

[0026] (9) In the control device described in any one of the above items (1) to (8), the calculation unit may perform multiple voltage simulations in parallel using multiple discharge patterns. According to the control device described in (9), it is possible to determine whether discharge is possible using multiple discharge patterns.

[0027] (10) An energy storage device according to one embodiment of the present invention includes a cell and a control device as described in any one of the above items (1) to (9). According to the control device described in (10), voltage simulation based on discharge patterns can be performed by a control device that incorporates such simulation. <Embodiment 1> 1. Battery 50 Description As shown in Figure 1, the automobile 10 is equipped with an engine 20 and a battery 50. The battery 50 is for auxiliary use in the automobile 10. The battery 50 is an example of an "energy storage device". The automobile 10 may also be equipped with an energy storage device for vehicle propulsion or a fuel cell.

[0028] As shown in Figure 2, the battery 50 comprises a battery pack 60, a circuit board unit 65, and a housing 71. The housing 71 comprises a main body 73 and a lid 74 made of synthetic resin material. The main body 73 is a bottomed cylindrical shape and comprises a bottom portion 75 and four side portions 76. The four side portions 76 form an opening 77 at the upper end of the main body 73.

[0029] The housing 71 houses the battery pack 60 and the circuit board unit 65. The circuit board unit 65 is a board unit on which various components (current interruption device 53, current detection unit 54 and control device 130 shown in Figure 5, etc.) are mounted on the circuit board 100, and is positioned adjacent to the battery pack 60, for example, above it, as shown in Figure 2. Alternatively, the circuit board unit 65 may be positioned adjacent to the side of the battery pack 60.

[0030] The cover 74 closes the opening 77 of the main body 73. An outer peripheral wall 78 is provided around the cover 74. The cover 74 has a projection 79 that is roughly T-shaped in plan view. A positive external terminal 51 is fixed to one corner of the front of the cover 74, and a negative external terminal 52 is fixed to the other corner. The circuit board unit 65 may be housed inside the cover 74 (for example, inside the projection 79) instead of the main body 73 of the housing 71.

[0031] The battery pack 60 is composed of multiple cells 62. As shown in Figure 4, each cell 62 houses an electrode body 83 together with a non-aqueous electrolyte within a rectangular parallelepiped (prismatic) case 82. The cell 62 is, for example, a lithium-ion secondary battery cell. The case 82 has a case body 84 and a lid 85 that closes the opening at its top.

[0032] The electrode body 83, although not shown in detail, consists of a negative electrode plate made of a copper foil substrate coated with an active material and a positive electrode plate made of an aluminum foil substrate coated with an active material, with a separator made of a porous resin film placed between them. Both are in the shape of a strip, and are wound flat so that they can be housed in the case body 84, with the negative electrode plate and positive electrode plate offset to opposite sides in the width direction relative to the separator. The electrode body 83 may be of a laminated type instead of the wound type.

[0033] A positive electrode terminal 87 is connected to the positive electrode plate via a positive electrode current collector 86, and a negative electrode terminal 89 is connected to the negative electrode plate via a negative electrode current collector 88. The positive electrode current collector 86 and the negative electrode current collector 88 each have a flat base portion 90 and legs 91 extending from the base portion 90. Through holes are formed in the base portion 90. The legs 91 are connected to the positive electrode plate or the negative electrode plate.

[0034] The positive terminal 87 and the negative terminal 89 each consist of a terminal body 92 and a shaft 93 that protrudes downward from the center of its lower surface. The terminal body 92 and shaft 93 of the positive terminal 87 are integrally molded from aluminum (a single material). In the negative 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 body 92 of the positive terminal 87 and the negative terminal 89 are positioned at both ends of the cover 85 via gaskets 94 made of insulating material, and are exposed to the outside from these gaskets 94, as shown in Figure 3.

[0035] The cover 85 has a pressure relief valve 95. The pressure relief valve 95 is located between the positive terminal 87 and the negative terminal 89. The pressure relief valve 95 is a safety valve. The pressure relief valve 95 opens when the internal pressure of the case 82 exceeds a limit, thereby reducing the internal pressure of the case 82.

[0036] Figure 5 is a block diagram showing the electrical configuration of the battery 50. The battery 50 comprises a battery pack 60, a current detection unit 54, a current interruption device 53, a voltage detection unit 110, a temperature sensor 58, and a management device 130.

[0037] The battery 50 is electrically connected to the vehicle ECU (Electronic Control Unit) 140, the alternator 150 which is a generator that produces electricity using the power of the engine 20, and the auxiliary equipment 160 of the automobile 10. The vehicle ECU 140 is a vehicle control unit that controls the automobile 10.

[0038] The vehicle ECU 140 controls the alternator 150 and auxiliary equipment 160. The vehicle ECU 140 may also control the drivetrain, such as the engine. There is not limited to one vehicle ECU 140; there may be multiple.

[0039] The auxiliary equipment 160 includes a specific load 160A and a general load 160B. The specific load 160A is the load targeted for the voltage simulation described later. The general load 160B includes, for example, headlights, wipers, car navigation systems, and air conditioning systems.

[0040] When the engine 20 is running, if the amount of power generated by the alternator 150 is greater than the power consumption of the auxiliary equipment 160, the battery 50 is charged by the alternator 150. If the amount of power generated by the alternator 150 is less than the power consumption of the auxiliary equipment 160, the battery 50 is discharged to compensate for the deficit.

[0041] While the engine 20 is stopped, the alternator 150 stops generating power. While power generation is stopped, the battery 50 is not charged and only discharges to the vehicle ECU 140 and auxiliary equipment 160.

[0042] The battery pack 60 has, for example, 12 cells 62 (see Figure 2), which are connected in 3 parallel and 4 series. Figure 5 shows three cells 62 connected in parallel represented by a single battery symbol. Cell 62 is an example of an "energy storage cell".

[0043] The energy storage cell is not limited to a prismatic cell; it may be a cylindrical cell or a pouch cell with a laminated film case. Battery 50 is rated at 12V.

[0044] The battery pack 60, the current interruption device 53, and the current detection unit 54 are connected in series via power lines 55P and 55N. Power lines 55P and 55N can be busbars BSB (see Figure 2), which are plate-shaped conductors made of metal materials such as copper.

[0045] As shown in Figure 5, power line 55P connects the positive external terminal 51 to the positive terminal of the battery pack 60. Power line 55N connects the negative external terminal 52 to the negative terminal of the battery pack 60. External terminals 51 and 52 are terminals for connecting the battery 50 to the automobile 10 (auxiliary equipment 160). The battery 50 can be electrically connected to the alternator 150 and the auxiliary equipment 160 via external terminals 51 and 52.

[0046] The current interruption device 53 is provided on the positive power line 55P. The current interruption device 53 may be a semiconductor switch such as an FET, or a relay with mechanical contacts. Preferably, the current interruption device 53 is a self-holding switch such as a latching relay.

[0047] The current interruption device 53 is of the normally closed type and is controlled to be in the closed state under normal circumstances. If there is any abnormality in the battery 50, the current interruption device 53 can be switched from the closed state to the open state, thereby interrupting the current to the battery pack 60.

[0048] The current detection unit 54 is provided on the negative terminal power line 55N. The current detection unit 54 may also be a shunt resistor. The resistive current detection unit 54 can measure the current I of the battery pack 60 based on the voltage Vr across the current detection unit 54. The resistive current detection unit 54 can distinguish between discharge and charge from the polarity (positive or negative) of the voltage. Alternatively, the current detection unit 54 may be a magnetic sensor.

[0049] The voltage detection unit 110 can detect the voltage Vs of cell 62 and the total voltage Vt of the battery pack 60. The temperature sensor 58 is attached to the battery pack 60 and detects the battery temperature TS of the battery pack 60 or the ambient temperature TS.

[0050] The management device 130 is mounted on the circuit board 100 (see Figure 2) and, as shown in Figure 5, comprises an arithmetic unit 131 such as a CPU, a storage unit 132, and a communication unit 133.

[0051] The communication unit 133 is connected to the vehicle ECU 140 via a signal line and communicates with the vehicle ECU 140. The management device 130 can receive signals from the vehicle ECU 140 regarding the operating status of the vehicle 10 (driving, stopped, parked, etc.) via communication.

[0052] The control device 130 monitors the status of the battery 50 based on the outputs of the voltage detection unit 110, the current detection unit 54, and the temperature sensor 58. In other words, it monitors the battery temperature TS, current I, and total voltage Vt of the battery pack 60.

[0053] The control device 130 estimates the State of Charge (SOC) [%] of the battery pack 60 based on the current I of the battery pack 60.

[0054] SOC (state of charge) is the ratio of remaining capacity to full charge capacity and is expressed by the following equation (1).

[0055] SOC=(Cr / Co)×100 (1) Co represents the cell's full charge capacity, and Cr represents the cell's remaining capacity.

[0056] The State of Charge (SOC) can be estimated based on the integral of the current I with respect to time, as shown in equation (2) below. The sign of the current I is positive during charging and negative during discharging.

[0057] SOC=SOCo+100×(∫Idt / Co)···(2) SOCo is the initial value of SOC, and I is the current.

[0058] The memory unit 132 stores the execution program for the voltage simulation and the data necessary for the program's execution. The data stored in the memory unit 132 includes data for the discharge pattern P, which will be described later. It also includes data for the internal resistance R of the battery pack 60 and the charge / discharge history of the battery 50.

[0059] The program may be stored on a recording medium such as a CD-ROM and used, transferred, or lent. The program may also be distributed via telecommunications lines.

[0060] 2. Voltage Simulation The voltage simulation estimates the time evolution of the total voltage Vt of the battery pack 60 using the discharge pattern P.

[0061] The discharge pattern P is the first time-series data D1 of the discharge current for a predetermined period of time. For example, the discharge pattern P in Figure 6A is the discharge current data for 12 seconds, defined by a graph with time on the horizontal axis and discharge current on the vertical axis. As an example, if the discharge pattern P is the discharge current required for the operation of a specific device 160A, and the operating time of the specific device 160A is 12 seconds, then the discharge pattern P is the data for 12 seconds.

[0062] Voltage simulations reveal the total voltages Vt0 to Vt12 when battery 50 is discharged for 12 seconds according to discharge pattern P, that is, when it is discharged for 12 seconds to a specific device 160A.

[0063] By comparing the total voltage Vt0 to Vt12 with the lower limit voltage VL of the total voltage Vt, it is possible to determine whether the battery 50 can discharge in discharge pattern P, that is, whether it can supply the power to operate a specific load of 160A to a specific load of 160A.

[0064] FIG. 7 is a time line of voltage simulation, and FIG. 8 is a simulation result. According to the simulation result of FIG. 8, since the total voltages Vt0 to Vt12 are not less than the lower limit voltage VL, in this case, the battery 50 can be discharged according to the discharge pattern P, that is, it is determined that power can be supplied to the specific load 160A (the specific load 160A can operate).

[0065] On the other hand, when a part of the total voltages Vt0 to Vt12 is lower than the lower limit voltage VL (Vt < VL), discharging according to the discharge pattern P is impossible, that is, it is determined that power cannot be supplied to the specific load 160A (the specific load 160A cannot operate).

[0066] As shown in FIG. 7, by periodically (t1, t2, t3, ···) performing voltage simulation, it is possible to periodically check whether discharging according to the discharge pattern P is possible.

[0067] When discharging according to the discharge pattern P is impossible, by prompting the vehicle ECU 140 to charge, the battery 50 can be returned to a state where power can be supplied to the specific load 160A.

[0068] The specific load 160A is, for example, a safety-related load such as an electric brake or an electric steering. In this embodiment, voltage simulation is performed for the purpose of functional safety of the vehicle. By performing voltage simulation for a safety-related load, when the vehicle power generation system (DCDC or alternator) fails during automatic driving, it is possible to determine whether power can be supplied from the battery 50 to the safety-related load during the period until the vehicle stops (for example, about 1 minute). The voltage simulation is not limited to functional safety and can be used for other applications and purposes such as ensuring comfort.

[0069] When the result of the voltage simulation is such that, for example, the determination at the time t2 in FIG. 7 indicates that discharging is possible (Vt > VL), the management device 130 determines that discharging is possible according to the discharge pattern (power can be supplied to the specific load 160A) during the period t2 to t3 until the next determination.

[0070] However, considering the discharge within the execution period T of the voltage simulation, it is possible that discharge according to discharge pattern P may not be possible (misjudgment of discharge feasibility).

[0071] To be more specific, battery 50 may discharge not only to the specific load of 160A that is the subject of the voltage simulation, but also to a general load of 160B. Depending on the type of general load of 160B, it may discharge continuously.

[0072] If there is discharge to a general load 160B (or if there is discharge to a load other than the general load 160B, such as a specific load 160A), the amount of charge stored in battery 50 will decrease even within the execution period T of the voltage simulation.

[0073] For example, at time t2, even if discharge using discharge pattern P is possible and the total voltage Vt12 after discharge has sufficient margin relative to the lower limit voltage VL, after t2, the margin relative to the lower limit voltage VL decreases due to discharge within the execution period T. If the margin is lost at time ta, then if discharge using discharge pattern P occurs during the period from time ta to the next judgment time t3, the total voltage Vt may fall below the lower limit voltage VL.

[0074] Figure 9 shows the change in total voltage Vt when discharge according to discharge pattern P starts at time tb. In this example, 10 to 11 seconds after the start of discharge at time tb, the total voltage Vt falls below the lower limit voltage VL, and battery 50 is depleted.

[0075] To solve these problems, the control device 130 uses an improved discharge pattern P for voltage simulation.

[0076] The improved discharge pattern P, as shown in Figure 6B, adds the second time series data D2 to the first time series data D1. In other words, the discharge time is the sum of the first time series data D1 and the second time series data D2, resulting in a discharge pattern that discharges an extra amount of time equal to the duration of the second time series data D2 compared to the case where only the first time series data D1 is discharged.

[0077] The second time-series data D2 is the time-series data of the discharge current that the battery 50 discharges to a general load 160B, etc., within the execution cycle T. The second time-series data D2 may use past actual values ​​(fixed values), or it may use the discharge current from the previous cycle T. It may also be switched according to the operating state of the automobile 10. In this embodiment, the discharge current is set to a fixed value of approximately 50A.

[0078] The improved discharge pattern P has data that is one cycle longer than the original discharge pattern P. The first time series data D1 is 12 seconds, the execution period T is 1 second, and the discharge pattern P has data for 13 seconds.

[0079] In this embodiment, the second time series data D2 is added before the first time series data D1 (left side of Figure 6B), but it may also be added after the first time series data D1 (right side of Figure 6B).

[0080] As shown in Figure 10, the calculation unit 131 takes (A) to (F) as inputs and estimates the time change of the total voltage Vt of the battery pack 60 when it is discharged according to discharge pattern P (voltage simulation).

[0081] Specifically, as shown in equation (3), the time evolution of the total voltage Vt is estimated by subtracting the voltage change ΔV of the total voltage due to discharge according to the discharge pattern P from the initial value Vt0 of the total voltage.

[0082] The voltage change ΔV can be calculated from information such as the state of charge (SOC), internal resistance (R), battery temperature (TS), and charge / discharge history (Z) of the battery pack 60. ΔV may be calculated using a predetermined formula or a reference table.

[0083] Vt=Vt0-ΔV(SOC, R, I, TS, Z) (3) Formula Vt is the total voltage, Vt0 is the initial value of the total voltage, ΔV is the voltage change, R is the internal resistance of the battery pack, I is the discharge current to a specific load, and TS is the battery temperature. Z is the charge and discharge history of battery 50.

[0084] (A) Improved discharge pattern P (B) Initial value of total voltage Vt0 of battery pack 60 (C) SOC of battery pack 60 (D) Internal resistance R of battery pack 60 (E) Battery temperature TS (F) Battery 50 charge / discharge history Z

[0085] Vt0 is the measured value from the voltage detection unit 110, and TS is the measured value from the temperature sensor 58. SOC is the calculated value using the current integration method. I is the data from the discharge pattern. The internal resistance R may be a fixed value (empirical value) stored in the memory unit 132, or it may be a calculated value obtained from the measured values ​​I and Vt from the current detection unit 54 and the voltage detection unit 110.

[0086] The reason for including the battery temperature TS as an input for the voltage simulation is to compensate for the internal resistance R at this temperature. If temperature compensation is not required, the battery temperature TS can be omitted from the input.

[0087] The reason for including the battery 50's charge / discharge history Z (number of charge / discharge cycles, etc.) as an input to the voltage simulation is to account for the increase in internal resistance R due to battery degradation. If battery degradation is not considered, the charge / discharge history Z can be omitted from the input.

[0088] In this embodiment, the specific load 160A is a safety-related load such as an electric brake or electric steering, but it could also be a door lock device or a device that switches the driving mode of the automobile 10. It could also be equipment used for emergency evacuation driving.

[0089] 3. Explanation of Effects By using a discharge pattern P with the second time-series data D2 added to the voltage simulation, it is possible to suppress the misjudgment that battery 50 is capable of discharge even when, in reality, there is no remaining capacity to discharge according to discharge pattern P, due to the discharge of battery 50 within the execution period T. Therefore, it is possible to accurately determine whether discharge is possible according to discharge pattern P.

[0090] <Embodiment 2> Embodiment 2, as shown in Figure 11, has two execution periods T for the voltage simulation, a first period T1 and a second period T2, and the execution period T can be switched.

[0091] T1 has a short period. By selecting T1, the cycle for determining whether discharge is possible or not based on the discharge pattern P is shortened, so if the battery 50 transitions from a dischargeable state to an undischargeable state, this can be detected early.

[0092] T2 is a long period. By selecting T2, the computational load on the control device 130 can be reduced and power consumption can be lowered.

[0093] The memory unit 132 stores the first discharge pattern P1 and the second discharge pattern P2. Figure 12A shows the waveform of the first discharge pattern P1, and Figure 12B shows the waveform of the second discharge pattern P2.

[0094] Both the first discharge pattern P1 and the second discharge pattern P2 are composed of the first time series data D1 and the second time series data D2.

[0095] The first discharge pattern P1 is for T1 (short period), and the second discharge pattern P2 is for T2 (long period). Due to the difference in period, the second time-series data D2 differs between the two discharge patterns P1 and P2. Specifically, the data length (discharge time) and current value are different.

[0096] Furthermore, the two discharge patterns P1 and P2 are used to determine whether or not power can be supplied to the same specific load of 160A, and the first time-series data D1 is common to both.

[0097] In this embodiment, the execution period T and discharge pattern P are switched according to the state of the automobile 10. As shown in Figure 12, when the automobile 10 is running, the first discharge pattern P1 is selected and the voltage simulation is performed in the first period T1, and when the automobile is not running, the second discharge pattern P2 is selected and the voltage simulation is performed in the second period T2.

[0098] Figure 13 is a flowchart of the voltage simulation. The voltage simulation execution process consists of seven steps, from S10 to S70.

[0099] After the management device 130 is started, the process proceeds to S10, where the calculation unit 131 determines whether the vehicle 10 is in motion. The operating status of the vehicle 10 can be determined by communication with the vehicle ECU 140. The operating status of the vehicle 10 can also be determined by the current I of the battery 50.

[0100] If the vehicle is in motion, the process proceeds to S20, and the calculation unit 131 reads the first discharge pattern P1 from the storage unit 132.

[0101] Subsequently, the calculation unit 131 performs a voltage simulation using the first discharge pattern P1 and estimates the voltage change of the total voltage Vt of the battery pack 60 when discharged using the first discharge pattern P1 (S40).

[0102] After performing the voltage simulation, the calculation unit 131 compares the total voltage Vt of the battery pack 60 with the lower limit voltage VL (S50).

[0103] If Vt ≥ VL (S60: NO), the calculation unit 131 determines that "discharge is possible with the first discharge pattern P1". The process then returns to S10.

[0104] While the automobile 10 is in motion, the voltage simulation execution process (S10, S20, S40, S50, S60) is performed in the first cycle T1.

[0105] When the vehicle 10 transitions to a non-moving state such as stopping or parking, it is determined to be NO in S10, and the process proceeds to S30, where the calculation unit 131 reads the second discharge pattern P2 from the storage unit 132.

[0106] After that, the calculation unit 131 performs voltage simulation using the read second discharge pattern P2, and estimates the voltage change of the total voltage Vt of the battery pack 60 when discharging in the second discharge pattern P2 (S40).

[0107] The calculation unit 131 compares the total voltage Vt of the battery pack 60 with the lower limit voltage VL, and determines whether discharging is possible with the second discharge pattern P2 (S50, S60).

[0108] When the vehicle 10 is not running, the execution process of voltage simulation (S10, S30, S40, S50, S60) is executed in the second period T2.

[0109] When the vehicle 10 is running or not running, if Vt < VL as a result of voltage simulation (S60: YES), the calculation unit 131 determines that "the battery 50 cannot be discharged by the discharge pattern P".

[0110] In this case, the process proceeds to S70, and the management device 130 notifies the vehicle ECU 140 of warning information and prompts charging of the battery 50.

[0111] By charging, the total voltage Vt of the battery 50 increases, and the battery returns to a state where discharging is possible by the first discharge pattern P or the second discharge pattern.

[0112] In this embodiment, when the vehicle 10 is running, voltage simulation is executed in a short period T1, so if the battery 50 reaches a state where it cannot be discharged by the first discharge pattern P1, it can be detected early.

[0113] On the other hand, when the vehicle 10 is not running, voltage simulation is executed in a long period T2, so power consumption of the management device 130 can be suppressed and energy can be saved.

[0114] <Embodiment 3> Embodiment 3 uses two discharge patterns, Pa and Pb, for voltage simulation, as shown in Figure 14. For example, the first discharge pattern Pa is for a first specific load (emergency communication device), and the second discharge pattern Pb is for a second specific load (hazard lamp).

[0115] The discharge patterns Pa and Pb differ in their first time-series data D1, but their second time-series data D2 is the same. The reason the first time-series data D1 differs is that the specific loads to which the power is supplied are different.

[0116] The calculation unit 131 uses two discharge patterns, Pa and Pb, and performs two voltage simulations in parallel. By performing two voltage simulations in parallel, it is possible to determine whether discharge is possible using the two types of discharge patterns, Pa and Pb.

[0117] In the example above, it is possible to determine whether power can be supplied to the first specific load (emergency communication equipment) and whether power can be supplied to the second specific load (hazard lights).

[0118] With this configuration, it becomes possible to select the discharge pattern of battery 50, which can be used by the vehicle ECU 140 to control the discharge of battery 50 and the vehicle load.

[0119] In this embodiment, since two discharge patterns Pa and Pb are stored, it is possible to perform a voltage simulation when simultaneous discharge occurs using the two discharge patterns (when power is supplied to multiple specific loads simultaneously), and to determine whether simultaneous discharge using multiple discharge patterns Pa and Pb is possible (whether simultaneous power supply to multiple specific loads is possible).

[0120] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of the present invention.

[0121] (1) The energy storage cell 62 is not limited to a lithium-ion secondary battery, but may be any other non-aqueous electrolyte secondary battery. The energy storage cell 62 is not limited to being connected in series or parallel, but may also be connected in series or as a single cell. A capacitor can be used instead of the energy storage cell 62.

[0122] (2) In the above embodiment, the battery 50 was mounted on the automobile 10, but it may also be mounted on a mobile body other than a vehicle, such as a ship or an aircraft. Furthermore, the battery (energy storage device) 50 is not limited to mobile bodies, but may also be used for stationary purposes, such as an energy storage device for absorbing fluctuations in a distributed power generation system.

[0123] (3) In the above embodiment, the control device 130 is provided inside the battery 50. The battery 50 only needs to be equipped with at least instruments such as a current detection unit 54 and a voltage detection unit 110, and the control device 130 and the current interruption device 53 may be located outside the battery 50.

[0124] (4) In the above embodiment 2, discharge patterns P1 and P2 were provided for each execution period T1 and T2, but the discharge pattern P may be common to all. For example, the period can be the average period Tav obtained by averaging T1 and T2, and the discharge current within the period can be time-series data using the average current Iav obtained by averaging the discharge currents I1 and I2 within T1 and T2.

[0125] (5) The second time series data D2 of the discharge pattern P may differ depending on the state of the vehicle 10. For example, when the vehicle is running and there is a lot of discharge, the value of the second time series data D2 may be increased (first discharge pattern P1 shown in Figure 12A), and when the vehicle is not running and there is little discharge, the value of the second time series data D2 may be decreased (second discharge pattern P2 shown in Figure 12B). By doing so, the error in the discharge current (the error between the actual discharge current and the simulated discharge current) can be reduced.

[0126] (6) The first time-series data D1 of the discharge pattern P can be any time-series data of the discharge current for a predetermined period of time, regardless of the purpose of the discharge. As illustrated in the embodiment, the purpose may be to discharge to a specific load 160A, or to loads other than the specific load 160A, such as the vehicle ECU 140 or a general load 160B. The purpose may also be to discharge to multiple loads. [Explanation of Symbols]

[0127] 10. Automobiles 50. Battery (energy storage device) 60 battery packs 130 Management device 131 Arithmetic section 132 Storage section 140 Vehicle ECU 160 Auxiliary equipment 160A specific load 160B general load

Claims

1. A control device that periodically performs voltage simulations of an energy storage device, The calculation unit and Including the memory unit, The aforementioned storage unit is The discharge pattern, consisting of time-series data of the discharge current, is stored. The aforementioned discharge pattern is obtained by adding a discharge pattern consisting of a second time series data to a discharge pattern consisting of a first time series data. The first time-series data is time-series data of the discharge current to the first load for a predetermined period of time. If a load other than the aforementioned first load is designated as the second load, The second time-series data is time-series data of the discharge current to the load, including the second load, within the voltage simulation execution period of the energy storage device. The aforementioned arithmetic unit, A control device that periodically performs a voltage simulation to estimate the voltage change of the energy storage device when the energy storage device discharges according to the discharge pattern, and periodically determines whether the energy storage device can discharge according to the discharge pattern based on the results of the voltage simulation.

2. A control device according to claim 1, The voltage simulation execution cycle is switchable and controlled by a management device.

3. A control device according to claim 2, The aforementioned energy storage device is for use in a vehicle. The aforementioned arithmetic unit, If the vehicle is in state 1, a voltage simulation is performed in the first cycle. A control device that, when the vehicle is in the second state, performs a voltage simulation in the second cycle.

4. A control device according to claim 3, The first state is when the vehicle is in motion, and the second state is when the vehicle is not in motion. The second cycle is longer than the first cycle of the control device.

5. A control device according to claim 3 or claim 4, The aforementioned second time-series data is managed by different devices depending on the vehicle's condition.

6. A control device according to claim 5, The first state is when the vehicle is in motion, and the second state is when the vehicle is not in motion. The control device shows that the second time series data when the vehicle is not in motion is smaller than the second time series data when the vehicle is in motion.

7. A control device according to claim 2 or claim 3, The memory unit determines the execution period of the voltage simulation as follows: A first discharge pattern having time-series data for the first cycle, A second discharge pattern having time-series data for the second cycle is stored, The aforementioned arithmetic unit, If the first period is selected, the first discharge pattern is selected and a voltage simulation is performed. A control device that, when the second cycle is selected, selects the second discharge pattern and performs a voltage simulation.

8. A control device according to claim 1 or claim 2, The calculation unit, in voltage simulation, A management device that estimates the voltage change of the energy storage device based on the State of Charge (SOC) of the energy storage device, the internal resistance of the cells, the discharge current, the temperature of the cells, and the charge / discharge history.

9. A control device according to claim 1 or claim 2, The calculation unit is a management device that performs multiple voltage simulations in parallel using multiple discharge patterns with different first time series data.

10. It is an energy storage device, Cells and, A power storage device comprising a control device according to claim 1 or claim 2.

11. A method for simulating the voltage of an energy storage device, The control device, including the calculation unit, periodically performs a voltage simulation to estimate the voltage change of the energy storage device when the energy storage device discharges according to the discharge pattern. The calculation unit periodically determines whether or not the energy storage device can discharge according to the discharge pattern based on the results of the voltage simulation. The aforementioned discharge pattern is obtained by adding a discharge pattern consisting of a second time series data to a discharge pattern consisting of a first time series data. The first time-series data is time-series data of the discharge current to the first load for a predetermined period of time. If a load other than the aforementioned first load is designated as the second load, A voltage simulation method wherein the second time-series data is time-series data of the discharge current to the load, including the second load, within the voltage simulation execution period of the energy storage device.

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