Secondary battery control system and secondary battery capacity recovery method

Abstract

The secondary battery 17 connected to the generator 13 is prevented from running out of power, while the capacity recovery process is performed in a timely and appropriate manner. [Solution] The secondary battery control system 11 comprises a generator 13, a secondary battery 17 connected to the generator 13 and a load 15, and a control device 19 that controls the charging and discharging of the secondary battery 17. The generator 13 has the function of supplying power to the secondary battery 17. The secondary battery 17 has the function of being charged by receiving power generated by the generator 13 and being discharged by outputting the requested power from the load 15. The control device 19 comprises a battery state acquisition unit 51 that acquires the state of charge (SOC) of the secondary battery 17, and a control unit 73 that, when the SOC acquired by the battery state acquisition unit 51 falls to the lower limit SOC of the secondary battery 17, controls the power generated by the generator 13 to be less than the requested power from the load 15.

Description

[Technical Field]

[0001] The present invention relates to a secondary battery control system and a secondary battery capacity recovery method. [Background technology]

[0002] Lithium-ion rechargeable batteries (hereinafter sometimes abbreviated as "LIBs") are a type of non-aqueous electrolyte rechargeable battery with high energy density. Therefore, LIBs are used in portable devices and, more recently, as power sources for electric vehicles (EVs). However, it is known that LIBs degrade with use, leading to a decrease in battery capacity.

[0003] In lithium-ion batteries (LIBs), lithium metal oxide is typically used as the active material for the positive electrode, and carbon materials such as graphite are used as the active material for the negative electrode. The positive and negative electrodes of an LIB are formed by adding a binder and conductive agent to a group of minute active material particles to create a slurry, which is then coated onto a metal foil.

[0004] Inside a lithium-ion battery (LIB), during charging, lithium ions released from the positive electrode's active material are absorbed into the negative electrode's active material. During discharge, lithium ions absorbed into the negative electrode's active material are released and absorbed into the positive electrode's active material. In this way, the movement of lithium ions between electrodes causes current to flow between the electrodes of the external circuit.

[0005] In such a lithium-ion battery (LIB), the following phenomena occur sequentially: (1) electrical isolation of the positive electrode active material, (2) electrical isolation of the negative electrode active material, and (3) fixation of lithium ions moving between electrodes to the negative electrode, resulting in a decrease in battery capacity.

[0006] The phenomenon described in (3) above occurs when lithium ions are confined within the negative electrode or when lithium ions are fixed to the negative electrode surface as a film due to the decomposition of the electrolyte. Of these, the capacity reduction due to lithium ions being trapped in the negative electrode can be recovered through electrochemical treatment. For example, the potential of the negative electrode can be raised compared to the operating potential range for LIBs. This releases the lithium ions trapped in the negative electrode, thereby restoring capacity. This capacity recovery process is equivalent to over-discharging the secondary battery.

[0007] Here, SOC (State of Charge) is an index that expresses the state of a battery as a percentage, with a fully charged state defined as 100% and a completely discharged state as 0%. According to this definition, over-discharge of a LIB means lowering the lower limit SOC to less than 0%, assuming that the completely discharged state of the LIB [0%] is the lower limit SOC.

[0008] Patent Document 1 discloses a method for reducing irreversible capacity and improving discharge capacity in lithium-ion secondary batteries by over-discharging the lithium-ion secondary battery to 1.0-2.0V with a minute current of 10mC to 1mC. As a result, it is claimed that the capacity of the lithium-ion secondary battery can be significantly increased. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 11-204148 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, the capacity recovery technology due to over-discharge described in Patent Document 1 has room for improvement. Specifically, when the State of Charge (SOC) of a lithium-ion secondary battery falls below 0%, the lithium-ion secondary battery becomes unable to supply power to the connected load equipment (power depletion). As a result, the load equipment stops working until the lithium-ion secondary battery is recharged by a power source such as a generator.

[0011] In order to prevent the situation where the operating load device falls into an unexpected stop state, it is required to limit the timing of discharging the lithium-ion secondary battery to a period during which the stop of the load device is allowed (for example, maintenance period). This has been a major obstacle to performing the capacity recovery process for the lithium-ion secondary battery at appropriate timings and frequencies.

[0012] The present invention has been made in view of the above circumstances, and an object thereof is to provide a secondary battery control system and a secondary battery capacity recovery method capable of performing the capacity recovery process in a timely manner while preventing power shortage of a secondary battery connected to a power supply.

Means for Solving the Problems

[0013] The secondary battery control system according to the present invention is a secondary battery control system configured to include a power supply, a secondary battery connected to the power supply and a load, and a control device that performs charge and discharge control of the secondary battery, where the power supply has a function of supplying power to the secondary battery, the secondary battery has a function of being charged by receiving the power supplied from the power supply and being discharged by outputting the required power related to the load, and the control device includes an acquisition unit that acquires the state of charge (SOC) which is the battery state of the secondary battery, and a control unit that controls so that the power supplied from the power supply becomes smaller than the required power related to the load when the SOC acquired by the acquisition unit drops to a lower limit SOC that defines the lower limit of the SOC related to the secondary battery, and is configured to include these as the most main features.

Effects of the Invention

[0014] According to the present invention, it is possible to perform the capacity recovery process in a timely manner while preventing power shortage of a secondary battery connected to a power supply. Problems, configurations, and effects other than those described above will be described in detail in the following embodiments.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic configuration diagram of a secondary battery control system according to an embodiment of the present invention. [Figure 2] It is a longitudinal sectional view conceptually showing a cell related to a lithium-ion secondary battery. [Figure 3] It is a cross-sectional view conceptually showing a plate group provided in the cell shown in FIG. 2. [Figure 4] It is a block configuration diagram conceptually showing the functions of a control device provided in the secondary battery control system. [Figure 5] It is a figure for explaining the results of an open circuit voltage curve analysis that separates the open circuit voltage curve of a secondary battery into the open circuit potential curves of the positive and negative electrodes. [Figure 6] It is a figure for explaining the operation of a comparative example related to the secondary battery control system. [Figure 7A] It is a figure for explaining the operation of the first embodiment related to the secondary battery control system. [Figure 7B] It is a figure for explaining the operation of the second embodiment related to the secondary battery control system. [Figure 8] It is a figure for explaining the volume retention rate characteristics of the first and second embodiments in comparison with the comparative example.

Modes for Carrying Out the Invention

[0016] The secondary battery control system and the secondary battery capacity recovery method according to the embodiments of the present invention will be described in detail while appropriately referring to the drawings. In the figures shown below, in principle, common reference numerals are attached to members having common functions or members having corresponding functions to each other, and duplicate explanations are omitted. Also, for convenience of explanation, the sizes and shapes of the members may be schematically represented with deformation or exaggeration.

[0017] [Schematic configuration of secondary battery control system 11 according to an embodiment of the present invention] First, the schematic configuration of the secondary battery control system 11 according to an embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram of the secondary battery control system 11 according to an embodiment of the present invention.

[0018] As shown in Figure 1, the secondary battery control system 11 according to an embodiment of the present invention comprises a generator 13, a secondary battery 17 connected to the generator 13 and a load 15, and a control device 19 that controls the charging and discharging of the secondary battery 17.

[0019] The secondary battery control system 11 is not particularly limited, but examples include PHEVs (plug-in hybrid vehicles), other transportation machinery, construction machinery, emergency power supplies, etc. A lithium-ion secondary battery (LIB) can be suitably used as the secondary battery 17. In the description of the secondary battery control system 11 according to the embodiment of the present invention, lithium-ion secondary batteries may be referred to collectively as "secondary batteries 17" as a broader concept.

[0020] The secondary battery 17 is charged by receiving power from the generator 13 according to the control signal of the control device 19, while being discharged by supplying power to the load 15. The load 15 outputs the required power request to the control device 19. The required power request output from the load 15 may be a value controllable by the control device 19, or it may be a value determined independently of the control device 19.

[0021] The control device 19 controls the discharge of the secondary battery 17 to supply power to the load 15 according to the required power request output from the load 15. The control device 19 also controls the power generated by the generator 13 based on the state of charge (SOC) of the secondary battery, and controls the charging of the secondary battery 17 by supplying the generated power to the secondary battery 17. The control device 19 may also control the output power of the secondary battery 17 to charge and discharge the secondary battery 17 in conjunction with the power generated by the generator 13. In this way, the control device 19 controls the charging and discharging of the secondary battery 17.

[0022] In the example shown in Figure 1, the generator 13 and the secondary battery 17 are connected in series. However, instead of this connection configuration, multiple secondary batteries 17 may be connected in parallel to a single generator 13, or multiple generators 13 may be connected in parallel to a single secondary battery 17. Furthermore, a configuration may be adopted that includes a bypass electrical circuit that supplies the power generated by the generator 13 directly to the load 15 without going through the secondary battery 17, if necessary. Furthermore, the secondary battery 17 may be configured to be rechargeable by an external power source other than the generator 13, such as grid power or renewable energy sources.

[0023] [Outline configuration of secondary battery 17] Next, the general configuration of the secondary battery 17 will be explained using a lithium-ion secondary battery (LIB) as an example, with reference to Figures 2 and 3 as appropriate. Figure 2 is a conceptual longitudinal cross-sectional view of a cell 21 related to a lithium-ion secondary battery 17. Figure 3 is a conceptual transverse cross-sectional view of the electrode plate group 23 provided in the cell 21 shown in Figure 2. Cell 21 is the smallest constituent unit of the lithium-ion secondary battery 17.

[0024] As shown in Figure 2, the cell 21 of the lithium-ion secondary battery 17 is composed of an electrode plate group 23, a positive electrode terminal 25 electrically connected to the positive electrode plate 31, a negative electrode terminal 27 electrically connected to the negative electrode plate 33, a separator 29, and an outer casing material 35. The exterior material 35 is a laminate film or the like. The external shape of the cell 21 is not particularly limited, but it may be rectangular as shown in Figure 2, or it may be cylindrical.

[0025] As shown in Figure 3, the electrode plate group 23 has a configuration in which positive electrode plates 31 and negative electrode plates 33 are arranged alternately so as to face each other with a separator 29 in between. However, the structure of the electrode plate group 23 is not limited to the laminated type shown in Figure 3, and may also be a wound type manufactured by stacking the positive electrode plates 31 and negative electrode plates 33 so as to face each other with a separator 29 in between, and then winding them in a circular shape.

[0026] The material of the separator 29 is not particularly limited, but for example, polypropylene can be used. In addition to polypropylene, the material of the separator 29 can be appropriately made of a microporous film or nonwoven fabric made of polyolefin such as polyethylene.

[0027] The positive electrode plate 31 and the negative electrode plate 33 can each be manufactured by coating a suitable metal current collector foil with a suitable mixture of electrode active material, conductive agent, binder, etc.

[0028] The current collector foil of the positive electrode plate 31 can be made of aluminum foil with a thickness of 10 to 100 μm, perforated aluminum foil with a thickness of 10 to 100 μm and a pore size of 0.1 to 10 mm, expanded metal, foamed metal plate, etc. In addition to aluminum, stainless steel, titanium, etc. can be used as appropriate materials for the positive electrode plate 31. The positive electrode plate 31 used in this invention is not limited in terms of material, shape, manufacturing method, etc., and any current collector can be used as appropriate.

[0029] The electrode active material of the positive electrode plate 31 is preferably one that contains a reactant species internally. If the secondary battery 17 is a lithium-ion secondary battery LIB, the reactant species is lithium ions. In this case, it contains a lithium-containing compound that allows for the reversible insertion and removal of lithium ions. The electrode active material of the positive electrode plate 31 is not particularly limited, but examples include lithium cobaltate, manganese-substituted lithium cobaltate, lithium manganeseate, lithium nickelate, lithium iron phosphate (olivine type), and other lithium transition metals. w Ni x Co y Mn zO2 (where w, x, y, and z are 0 or positive values) is used. The electrode active material of the positive electrode plate 31 may contain one or more of the above materials.

[0030] On the other hand, the current collector foil of the negative electrode plate 33 can be made of copper foil with a thickness of 10 to 100 μm, perforated copper foil with a thickness of 10 to 100 μm and a hole diameter of 0.1 to 10 mm, expanded metal, foamed metal plate, etc. In addition to copper, stainless steel, titanium, etc. can be used as appropriate for the material of the negative electrode plate 33. The negative electrode plate 33 used in this invention is not limited in terms of material, shape, manufacturing method, etc., and any current collector can be used as appropriate.

[0031] The electrode active material of the negative electrode plate 33 contains a material that allows lithium ions to be reversibly inserted into and removed from the secondary battery 17, in the case of a lithium-ion secondary battery LIB. The electrode active material for the negative electrode plate 33 is not particularly limited, but examples include natural graphite, composite carbonaceous materials obtained by forming a film on natural graphite using a dry CVD method or a wet spray method, artificial graphite produced by firing using resin materials such as epoxy or phenol or pitch-based materials obtained from petroleum or coal as raw materials, silicon (Si), silicon-mixed graphite, non-graphitizable carbon materials, and lithium titanate Li4Ti5O 12 Niobium-titanium oxide TiNb2O7 is used. The electrode active material of the negative electrode plate 33 may contain one or more of the above materials.

[0032] The electrode plate group 23, including the positive electrode plate 31 and the negative electrode plate 33, is impregnated with an electrolyte. The electrolyte is not particularly limited, but in the case of a lithium-ion secondary battery LIB, for example, an electrolyte is used in which lithium salts such as lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, lithium iodide, lithium chloride, lithium bromide, LiB[OCOCF3]4, LiB[OCOCF2CF3]4, LiPF4(CF3)2, LiN(SO2CF3)2, LiN(SO2CF2CF3)2, or two or more of these mixed lithium salts are dissolved in an aprotic organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), or ethyl propyl carbonate (EPC), or a solvent of two or more of these mixed organic compounds.

[0033] A solid electrolyte may be used instead of the electrolyte solution described above. While not particularly limited, ion-conducting polymers such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, and polyethylene oxide can be used as solid electrolytes. When a solid electrolyte is used instead of the electrolyte solution, the separator 29 can be omitted.

[0034] A metal tab is electrically connected to the current collector foil of both the positive electrode plate 31 and the negative electrode plate 33. The outer casing material 35 is sealed so that only the tab portion is exposed to the outside of the outer casing material 35. With this configuration, the tab is configured to form the positive electrode terminal 25 and the negative electrode terminal 27 shown in Figure 2.

[0035] [Functions of the control device 19 provided in the secondary battery control system 11] Next, the functions of the control device 19 provided in the secondary battery control system 11 will be explained with reference to Figure 4. Figure 4 is a block diagram conceptually representing the functions of the control device 19 provided in the secondary battery control system 11.

[0036] As shown in Figure 4, the control device 19 is configured to include a battery state acquisition unit 51, a battery state determination unit 53, a storage unit 55, a battery state calculation unit 57, a timer unit 59, a generator state acquisition unit 61, a generator state calculation unit 63, a capacity recovery control determination unit 71, and a normal operation control unit 75 and a capacity recovery control unit 77 provided in the control unit 73.

[0037] The control device 19 is composed of a microcomputer (not shown) equipped with, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. The CPU executes data and programs stored in ROM using RAM as a working area and performs predetermined control. More specifically, the control device 19 controls the charging and discharging of the secondary battery 17 and the operation of the generator 13 based on the battery state of the secondary battery 17 and the generator state of the generator 13 acquired by a state sensor (details below).

[0038] The battery state acquisition unit 51 acquires the value of a battery state signal related to the secondary battery 17 using state sensors (consisting of one or more combinations of a voltage sensor, a current sensor, and a temperature sensor) provided in the secondary battery 17, and outputs the acquired battery state signal value to the battery state determination unit 53. Among the state sensors, the voltage sensor (not shown) outputs a battery voltage signal which is the battery voltage value Vbt of the secondary battery 17. Among the state sensors, the current sensor (not shown) outputs a battery current signal which is the battery current value Ibt flowing through the secondary battery 17. Among the state sensors, the temperature sensor (not shown) outputs a battery temperature signal which is the battery temperature value Tbt of the secondary battery 17.

[0039] Here, the value of the battery status signal is not particularly limited, but an example is the combination of the battery voltage value Vbt, which is the output of the state sensor (voltage sensor) provided in the secondary battery 17, and the battery current value Ibt, which is the output of the state sensor (current sensor) provided in the secondary battery 17. In the following explanation, unless otherwise specified, the combination of the battery voltage value Vbt and the battery current value Ibt will be used as an example to explain the value of the battery status signal.

[0040] The battery state determination unit 53 receives the battery state signal values ​​(battery voltage value Vbt and battery current value Ibt) related to the secondary battery 17 obtained by the battery state acquisition unit 51, and outputs the received battery state signal values ​​together with time information (for example, current time information, etc.) based on the timer unit 59 to the storage unit 55 for storage.

[0041] Furthermore, the battery state determination unit 53 processes the received battery state signal value (battery current value Ibt) using time information based on the timer unit 59, and outputs the processed data to the storage unit 55 for storage. Specifically, the battery state determination unit 53 performs time integration processing on the battery current value Ibt using time information based on the timer unit 59 (for example, discharge time / charge time of the secondary battery 17), and outputs the resulting electrical quantity value Wbt to the storage unit 55 for storage.

[0042] Furthermore, the battery state determination unit 53 compares the calculated value (SOC) related to the battery state of the secondary battery 17 by the battery state calculation unit 57 with the reference value related to the battery state of the secondary battery 17 stored in the storage unit 55. Based on the comparison result, the battery state determination unit 53 determines the battery state of the secondary battery 17 and outputs the determination result to the capacity recovery control determination unit 71.

[0043] For details regarding the battery state determination function of the battery state determination unit 53, which determines the battery state of the secondary battery 17 based on a comparison result of a calculated value and a reference value related to the battery state, please refer to the information in paragraphs 0030-0069, etc., of Japanese Patent Application Publication No. 2021-005543. The information in paragraphs 0030-0069, etc., of Japanese Patent Application Publication No. 2021-005543 is incorporated into this specification by this reference.

[0044] The storage unit 55 pre-stores, as initial values, a correspondence table of State of Charge (SOC) to the battery voltage (battery voltage value Vbt) of the secondary battery 17, battery information including the initial capacity of the secondary battery 17, upper and lower voltage limit values ​​and maximum charge / discharge current value of the secondary battery 17, and generator information (including maximum power generation) necessary for calculating the remaining power generation capacity of the generator 13. The storage unit 55 also stores the data after the information processing by the battery state determination unit 53, and the electrical quantity value Wbt after the time integration processing. The storage unit 55 outputs the stored data and other information to the battery state determination unit 53, the battery state calculation unit 57, and the generator state calculation unit 63 as needed.

[0045] The battery state calculation unit 57 calculates physical quantities for determining the battery state of the secondary battery 17 based on information such as data acquired via one of the battery state acquisition unit 51, battery state determination unit 53, or storage unit 55, and outputs the calculation result to the battery state determination unit 53. Specifically, the battery state calculation unit 57 calculates the SOC corresponding to the battery voltage value Vbt based on, for example, the battery voltage value Vbt obtained via the battery state acquisition unit 51 and the correspondence table of SOC to the battery voltage value Vbt related to the secondary battery 17 stored in the storage unit 55, and outputs the calculated SOC to the battery state determination unit 53.

[0046] For details regarding the physical quantity calculation function of the battery state calculation unit 57 for determining the battery state of the secondary battery 17, please refer to the information in paragraphs 0030-0031, etc., of Japanese Patent Publication No. 2021-005543. The information in paragraphs 0030-0031, etc., of Japanese Patent Publication No. 2021-005543 is incorporated into this specification by this reference.

[0047] The timer unit 59 receives the timing of the start / end of charging and the start / end of discharging, and measures the time accordingly, and outputs the measured time information (charging time and discharging time) to the battery state determination unit 53.

[0048] The generator status acquisition unit 61 acquires the value of the generator status signal related to the generator 13 using the status sensors (including voltage sensors and current sensors) provided on the generator 13, and outputs the acquired value of the generator status signal to the generator status calculation unit 63. Specifically, the voltage sensor (not shown) among the state sensors outputs a generated voltage signal, which is the generated voltage value Vgn of the generator 13. The current sensor (not shown) among the state sensors outputs a generated current signal, which is the generated current value Ign flowing through the generator 13.

[0049] Here, the value of the generator status signal is not particularly limited, but an example is the combination of the generated voltage value Vgn, which is the output of the state sensor (voltage sensor) provided on the generator 13, and the generated current value Ign, which is the output of the state sensor (current sensor) provided on the generator 13. In the following explanation, unless otherwise specified, the combination of the generated voltage value Vgn and the generated current value Ign will be used as an example to explain the value of the generator status signal.

[0050] The generator state calculation unit 63 calculates physical quantities for determining the generator state of the generator 13 based on information such as data acquired via either the storage unit 55 or the generator state acquisition unit 61, and outputs the calculation result to the capacity recovery control determination unit 71. Specifically, the generator state calculation unit 63 calculates the remaining power generation capacity, which is a physical quantity for determining the generator state of the generator 13, based on the current power generation power calculated based on the power generation voltage value Vgn and power generation current value Ign obtained via the generator state acquisition unit 61, and the time that the calculated current power generation power can be maintained. The unit then outputs the calculated remaining power generation capacity to the capacity recovery control determination unit 71.

[0051] The capacity recovery control determination unit 71 determines whether to execute normal operation control or capacity recovery control based on the battery state (SOC) of the secondary battery 17 determined by the battery state determination unit 53, the remaining power generation capacity of the generator 13 calculated by the generator state calculation unit 63, and the power request related to the load 15, and outputs the determination result to both the normal operation control unit 75 and the capacity recovery control unit 77, respectively.

[0052] The capacity recovery control determination unit 71 determines whether capacity recovery control is necessary based on the degree of degradation of the secondary battery 17, its usage history, etc. Specifically, the capacity recovery control determination unit 71 determines that capacity recovery control is necessary, for example, when the degree of degradation of the secondary battery 17 is greater than a predetermined degradation threshold and capacity recovery of the secondary battery 17 is expected.

[0053] However, even if the capacity recovery control determination unit 71 has made a preliminary determination that capacity recovery control is necessary, if it is determined that the secondary battery 17 cannot be recharged to the lower limit SOC (=0%) or higher after executing capacity recovery control, considering the remaining power generation capacity of the generator 13 and the power requirements of the load 15, the unit makes a final determination that normal operation control should be executed instead of capacity recovery control. Here, an example of a case in which it is determined that the secondary battery 17 cannot be recharged to the lower limit SOC (=0%) or higher after the execution of capacity recovery control is when the generator 13 is a power supply that involves fuel consumption, such as a diesel generator, and the remaining fuel (corresponding to the surplus power generation capacity) is relatively small, so in order to meet the power demands of the load 15, the secondary battery 17 cannot be recharged to the lower limit SOC or higher after the execution of capacity recovery control. This configuration prevents the secondary battery 17 from unexpectedly falling into an over-discharge state after the capacity recovery control is executed. This is because keeping the secondary battery 17 in an unexpected over-discharge state for a long period of time may accelerate its deterioration.

[0054] Furthermore, the capacity recovery control determination unit 71 may adopt a configuration that takes into account user requests related to the load 15 to which the secondary battery 17 is connected when making a final determination that capacity recovery control is required. With this configuration, charging and discharging control of the secondary battery 17 can be performed while taking the user's intentions into account, thereby contributing to improved convenience for the user. In this case, the control device 19 may be configured to include a touch panel display that shows the battery status of the secondary battery 17 provided in the load 15 or accepts user requests. Furthermore, the control device 19 may have a communication function that enables information communication via a communication medium with a mobile terminal such as a smartphone owned by the user, and may adopt a configuration in which user requests are transferred from the mobile terminal to the control device 19 via the communication medium.

[0055] If the capacity recovery control determination unit 71 makes a final determination that capacity recovery control for the secondary battery 17 is unnecessary, the capacity recovery control determination unit 71 instructs the normal operation control unit 75 to perform normal operation. In response, the normal operation control unit 75 outputs control signals related to normal operation to the generator 13 and the secondary battery 17.

[0056] To prevent the secondary battery 17 from falling into an over-discharge state during normal operation, a normative lower limit voltage value Vlow is set, which defines a normative lower limit voltage value for the battery voltage (battery voltage value Vbt) related to the secondary battery 17. The normative lower limit voltage value Vlow is set in accordance with the lower limit of SOC. That is, the state in which the battery voltage reaches the normative lower limit voltage value Vlow corresponds to SOC 0%. This is stored in memory unit 55.

[0057] During normal operation, the normal operation control unit 75 performs normal operation control so that the battery voltage value Vbt does not fall below the standard lower limit voltage value Vlow. That is, when the battery voltage value Vbt related to the secondary battery 17 is likely to fall below the standard lower limit voltage value Vlow, the normal operation control unit 75 outputs a control signal to increase the power generation output of the generator 13 to the generator 13. Also, when the control device 19 can control the power consumption of the load 15, the normal operation control unit 75 may adopt a configuration to reduce the power demand related to the load 15. Thereby, the normal operation control unit 75 can perform charge / discharge control so that the battery voltage value Vbt does not fall below the standard lower limit voltage value Vlow.

[0058] On the other hand, when the capacity recovery control determination unit 71 finally determines that capacity recovery control related to the secondary battery 17 is necessary, the capacity recovery control determination unit 71 causes the capacity recovery control unit 77 to perform a capacity recovery process according to the capacity recovery control. In response to this, the capacity recovery control unit 77 outputs a control signal related to the capacity recovery process to the generator 13 and the secondary battery 17.

[0059] During the capacity recovery process, the capacity recovery control unit 77 performs capacity recovery control so that the power generation output of the generator 13 is lower than the power demand related to the load 15. At this time, the battery voltage value Vbt related to the secondary battery 1 7 is controlled to fall below the standard lower limit voltage value Vlow. That is, the capacity recovery control unit 77 outputs a control signal to reduce the power generation output of the generator 13 to the generator 13 so that the power generation output of the generator 13 is lower than the power demand related to the load 15. Instead of this, when the control device 19 can control the power consumption of the load 15, a configuration to increase the power demand related to the load 15 may be adopted. Thereby, the capacity recovery control unit 77 can control so that the battery voltage value Vbt falls below the standard lower limit voltage value Vlow.

[0060] In the capacity recovery control related to the capacity recovery control unit 77, during the capacity recovery process, the battery voltage value Vbt of the secondary battery 17 is controlled to fall below the reference lower limit voltage value Vlow. At this time, the sum of the power output of the generator 13 and the discharge output of the secondary battery 17 is controlled to satisfy the power requirements of the load 15. This allows the capacity recovery process of the secondary battery 17 to be carried out accurately while ensuring the operation of the load 15.

[0061] During the capacity recovery process, the battery voltage Vbt of the secondary battery 17 is controlled to be below the reference lower limit voltage Vlow. It is preferable to set the battery voltage Vbt to a value exceeding the critical lower limit voltage Vlow_lim. Here, the critical lower limit voltage Vlow_lim is a critical lower limit voltage value set from the viewpoint of ensuring the soundness of the secondary battery 17. If the secondary battery 17 is over-discharged, the materials of the positive and negative electrodes deteriorate and the electrolyte decomposes due to the over-discharge, ultimately impairing the soundness of the secondary battery 17. Therefore, the battery voltage value Vbt of the secondary battery 17 during the capacity recovery process is kept at a value exceeding the critical lower voltage limit value Vlow_lim. With this configuration, the integrity of the secondary battery 17 can be guaranteed even when capacity recovery processing is performed.

[0062] The critical lower voltage limit value Vlow_lim may be a fixed value as appropriate, but it is more preferable to calculate it each time based on the degradation state of the secondary battery 17 during the capacity recovery process. This configuration ensures that the accelerated degradation of the secondary battery 17 can be reliably suppressed.

[0063] To obtain the critical lower voltage value Vlow_lim based on the degradation state of the secondary battery 17, the following procedure should be followed. First, data related to the charge-discharge curve of the secondary battery 17 to be restored is obtained based on the battery voltage and charge / discharge capacity of the secondary battery 17. The data related to the charge-discharge curve is table data that relates the change in open circuit voltage (OCV) to the change in charge / discharge capacity. The battery voltage related to the charge and discharge characteristics of the secondary battery 17 should preferably be close to the open-circuit voltage OCV. The open-circuit voltage OCV is the terminal voltage of the secondary battery 17 when no load 15 is connected to the secondary battery 17 (when no current is flowing).

[0064] The method of energizing the secondary battery 17 used to acquire data related to the charge-discharge curve is not particularly limited. For example, data related to the charge-discharge curve may be acquired while discharging the secondary battery 17 with a small and predetermined current from a fully charged state to a fully discharged state, or the charge-discharge curve may be acquired while charging the secondary battery 17 from a fully discharged state to a fully charged state.

[0065] Alternatively, data related to the charge-discharge curve may be obtained by repeating a unit discharge cycle, in which the secondary battery 17 is discharged at a predetermined current for a predetermined time followed by a predetermined rest period, until the battery moves from a fully charged state to a completely discharged state.

[0066] Furthermore, data related to the charge-discharge curve may be obtained by repeating a unit charge cycle, in which the secondary battery 17 is charged with a predetermined current for a predetermined time, followed by a predetermined rest period, until the battery moves from a completely discharged state to a fully charged state.

[0067] Alternatively, data related to the charge-discharge curve of the secondary battery 17 can be estimated by statistically processing the current waveform and voltage waveform of the secondary battery 17 while it is supplying power to the load 15, or by estimating the open-circuit voltage OCV by performing regression calculation (reproduction calculation) based on an equivalent circuit.

[0068] In addition, regarding the energizing mode of the secondary battery 17 used when acquiring the data related to the charge-discharge curve, the energizing modes of "discharging the secondary battery 17 from a fully charged state to a completely discharged state" and "charging the secondary battery 17 from a completely discharged state to a fully charged state" were explained as examples, but the present invention is not limited to these examples.

[0069] The energizing mode of the secondary battery 17 used when acquiring the data related to the charge-discharge curve is not necessarily limited to discharging or charging within the aforementioned SOC range. A wider SOC range is desirable when performing charge-discharge, and it is most desirable to charge and discharge within the 100% SOC range. However, if the subsequent processes can be carried out smoothly, charge-discharge may be performed within any SOC range from a fully charged state to a completely discharged state.

[0070] Next, based on the charge-discharge characteristics of the positive and negative electrodes that were measured in advance, data related to the charge-discharge curve of the secondary battery 17 is constructed using regression calculation (reproduction calculation). The reproduction calculation process uses, for example, a correction parameter m p , m n , C p , C n Use the following method:

[0071] Regarding the charge-discharge characteristics per reference mass or reference area of ​​the positive and negative electrodes, the respective charge-discharge capacities are given by m p , m n After multiplying by C p , C n The calculation values ​​of the charge-discharge curves for the positive and negative electrodes are obtained by adding and correcting the values. The calculation values ​​of the charge-discharge curves for the positive and negative electrodes obtained in this way are then used to determine the difference between the positive and negative electrode potentials corresponding to the same charge-discharge capacity, thereby obtaining the calculation values ​​of the charge-discharge curve for the secondary battery 17. The capacity correction parameter m for the positive and negative electrodes is adjusted so that the calculation values ​​of the charge-discharge curve for the secondary battery 17 match the measured values. p , m n , C p , C n Adjust.

[0072] Figure 5 shows an example of the results of the reproduction calculation process. Figure 5 was created using open-circuit voltage curve analysis, which separates the open-circuit voltage curve of the secondary battery 17 into open-circuit potential curves for the positive and negative electrodes. The solid line represents the open-circuit voltage curve of the secondary battery 17, the dashed line represents the open-circuit potential curve of the positive electrode, and the dotted line represents the open-circuit potential curve of the negative electrode. In the example shown in Figure 5, a capacitance difference occurs between the positive and negative electrodes, and the discharge end of the negative electrode coincides with the discharge end of the secondary battery 17.

[0073] Finally, the battery voltage of the secondary battery 17 corresponding to the completely discharged state of the negative electrode obtained by the reproduction calculation process is calculated. Specifically, for example, as shown in Figure 5, the negative electrode potential is 2.0V vs. Li / Li + The battery voltage of the secondary battery 17 corresponding to the charge / discharge capacity is calculated. The battery voltage of the secondary battery 17 calculated in this way is set to the critical lower voltage value Vlow_lim.

[0074] Furthermore, even if the battery voltage of the secondary battery 17 during the capacity recovery process exceeds the critical lower limit voltage value Vlow_lim, it is preferable to terminate the capacity recovery process if the battery voltage of the secondary battery 17 reverses and rises during the process. This is because, in cases where the battery voltage of the secondary battery 17 reverses and rises during the capacity recovery process, there is a risk that dissolution of the current collector of the negative electrode may occur as a side reaction.

[0075] After the capacity recovery process, the capacity recovery control unit 77 charges the secondary battery 17 by controlling the power output of the generator 13 to be significantly larger than the power demand of the load 15, thereby controlling the battery voltage of the secondary battery 17 to exceed the reference lower limit voltage value Vlow.

[0076] Whether or not the secondary battery control system 11 according to the embodiment of the present invention is implemented can be determined based on the change in the state of charge (SOC) of the secondary battery 17. Here, the change in the SOC of the secondary battery 17 is displayed on a display device (not shown) connected to the control device 19. In other words, if the secondary battery control system 11 is in operation (during normal operation) and the SOC of the secondary battery 17 drops to 0%, and the secondary battery 17 is not recharged, it can be determined that the present invention is being implemented. Here, the case in which the SOC of the secondary battery 17 drops to 0% means that the battery voltage value Vbt of the secondary battery 17 has dropped to the reference lower limit voltage value Vlow. According to the secondary battery control system 11 of the present invention, it is possible to prevent the secondary battery 17 connected to the generator 13 from running out of power while performing capacity recovery processing in a timely and appropriate manner.

[0077] [Operation compared to comparative examples of the first and second embodiments] Next, the operation of the secondary battery control system 11 will be explained in comparison with comparative examples of the first and second embodiments, with reference to Figures 6, 7A, and 7B as appropriate. Figure 6 is a diagram illustrating the operation of a comparative example of the secondary battery control system 11. Figure 7A is a diagram illustrating the operation of the first embodiment of the secondary battery control system 11. Figure 7B is a diagram illustrating the operation of the second embodiment of the secondary battery control system 11.

[0078] The comparative example shown in Figure 6 illustrates the change in the battery voltage value Vbt over time when only normal operation control is performed, regardless of the change in the battery voltage value Vbt over time.

[0079] In the comparative example, at time t1, the battery voltage Vbt dropped to the reference lower limit voltage Vlow, but the normal operation control unit 75 continued normal operation control. That is, from time t1 onward, the normal operation control unit 75 controlled the generator 13 so that its output was greater than the power demand for the load 15. As a result, the battery voltage Vbt rose, returning to its reference lower limit voltage Vlow.

[0080] In contrast, the first embodiment shown in Figure 7A illustrates the change in the battery voltage value Vbt over time when the control mode is switched from normal operation control to capacity recovery control in response to the change in the battery voltage value Vbt over time.

[0081] In the first embodiment, at time t11, the battery voltage value Vbt dropped to the reference lower limit voltage value Vlow, so the capacity recovery control determination unit 71 switches the control mode from normal operation control to capacity recovery control. During the period from time t11 to t13, the capacity recovery control unit 77 performs capacity recovery control. During this period, the capacity recovery control unit 77 controls the battery voltage value Vbt so that it falls below the reference lower limit voltage value Vlow and exceeds the non-critical lower limit voltage value Vlow_nl. Here, the non-critical lower limit voltage value Vlow_nl is appropriately set to a battery voltage value Vbt that falls within the range of being less than the reference lower limit voltage value Vlow and greater than the critical lower limit voltage value Vlow_lim.

[0082] During the period from time t11 to t12, the capacity recovery control unit 77 controls the generator 13 so that its output is smaller than the power demand for the load 15. As a result, the battery voltage value Vbt decreases from the reference lower limit voltage value Vlow to the noncritical lower limit voltage value Vlow_nl.

[0083] During the period from time t12 to t13, the capacity recovery control unit 77 controls the generator 13 so that its output is greater than the power demand for the load 15. As a result, the battery voltage value Vbt rises from the noncritical lower limit voltage value Vlow_nl to the reference lower limit voltage value Vlow.

[0084] At time t13, the battery voltage Vbt has risen to the reference lower limit voltage Vlow, so the capacity recovery control determination unit 71 switches the control mode from capacity recovery control to normal operation control. From time t13 onward, the normal operation control unit 75 controls the generator 13 so that its output is greater than the power demand for the load 15. As a result, the battery voltage Vbt rises starting from the reference lower limit voltage Vlow.

[0085] Next, we will describe the second embodiment shown in Figure 7B. The first embodiment shown in Figure 7A and the second embodiment shown in Figure 7B differ in the lower limit value of the battery voltage Vbt during capacity recovery control. Specifically, in the first embodiment shown in Figure 7A, the lower limit value of the battery voltage Vbt during capacity recovery control is set to the non-critical lower limit voltage value Vlow_nl, while in the second embodiment shown in Figure 7B, the lower limit value of the battery voltage Vbt during capacity recovery control is set to the critical lower limit voltage value Vlow_lim. Note that the critical lower limit voltage value Vlow_lim is set to a smaller value than the non-critical lower limit voltage value Vlow_nl. <Vlow_nl〕。

[0086] In the second embodiment, at time t21, the battery voltage value Vbt has fallen to the reference lower limit voltage value Vlow, so the capacity recovery control determination unit 71 switches the control mode from normal operation control to capacity recovery control. During the period from time t21 to t23, the capacity recovery control unit 77 performs capacity recovery control. During this period, the capacity recovery control unit 77 controls the battery voltage value Vbt so that it falls below the reference lower limit voltage value Vlow and exceeds the critical lower limit voltage value Vlow_lim.

[0087] During the period from time t21 to t22, the capacity recovery control unit 77 controls the generator 13 so that its output is smaller than the power demand for the load 15. As a result, the battery voltage value Vbt decreases from the reference lower limit voltage value Vlow to the critical lower limit voltage value Vlow_lim.

[0088] During the period from time t22 to t23, the capacity recovery control unit 77 controls the generator 13 so that its output is greater than the power demand for the load 15. As a result, the battery voltage Vbt rises from the critical lower limit voltage Vlow_lim to the reference lower limit voltage Vlow.

[0089] At time t23, the battery voltage Vbt rose to the reference lower limit voltage Vlow, so the capacity recovery control determination unit 71 switches the control mode from capacity recovery control to normal operation control. From time t23 onward, the normal operation control unit 75 controls the generator 13 so that its output is greater than the power demand for the load 15. As a result, the battery voltage Vbt rises starting from the reference lower limit voltage Vlow.

[0090] [Volume retention characteristics of the first and second embodiments (compared to the comparative example)] Next, the volume retention characteristics of the first and second embodiments in comparison with the comparative example will be described with reference to Figure 8. Figure 8 is a diagram illustrating the volume retention characteristics of the first and second embodiments in comparison with the comparative example. In Figure 8, the vertical axis represents the capacity retention rate [%], and the horizontal axis represents the number of days the secondary battery 17 is in use. The solid lines in Figure 8 show the volume retention rate characteristics of the first and second embodiments, and the dashed lines in Figure 8 show the volume retention rate characteristics of the comparative example. As shown in Figure 8, the volume retention characteristics of the first and second embodiments show that a higher capacity retention rate can be maintained compared to the comparative example. Furthermore, in the second embodiment, the battery voltage value Vbt was lowered to the critical lower voltage value Vlow_lim, resulting in a greater capacity recovery effect. The capacity retention characteristics of the second embodiment also show that a higher capacity retention rate can be maintained compared to the first embodiment.

[0091] [Effects and Effects of the Secondary Battery Control System 11 According to an Embodiment of the Present Invention] The secondary battery control system 11 based on the first perspective is: A secondary battery control system 11 comprises a generator (power supply) 13, a secondary battery 17 connected to the generator 13 (power supply) and load 15, and a control device 19 that controls the charging and discharging of the secondary battery 17, The generator (power supply) 13 has the function of supplying power to the secondary battery 17. The secondary battery 17 has the function of being charged by receiving power generated (power supplied) from the generator (power supply) 13, and being discharged by outputting the required power from the load 15. The control device 19 is A battery state acquisition unit (acquisition unit) 51 acquires the State of Occurrence (SOC), which is the battery state of the secondary battery 17, When the State of Charge (SOC) acquired by the battery state acquisition unit (acquisition unit) 51 falls to a lower limit SOC that defines the lower limit of the SOC related to the secondary battery 17, the control unit 73 controls the generated power (supplied power) related to the generator (power supply) 13 to be less than the required power related to the load 15, It is characterized by being configured to include the following.

[0092] In the secondary battery control system 11 based on the first perspective, the battery state acquisition unit (acquisition unit) 51 acquires the State of Charge (SOC), which is the battery state of the secondary battery 17. When the SOC acquired by the battery state acquisition unit (acquisition unit) 51 falls to the lower limit SOC, the control unit 73 controls the generated power (supplied power) from the generator (power supply) 13 to be less than the required power for the load 15.

[0093] In the secondary battery control system 11 based on the first perspective, the State of Charge (SOC) acquired by the battery state acquisition unit (acquisition unit) 51 is a concept equivalent to the battery voltage value Vbt. This is because the battery voltage value Vbt can be converted to SOC on a one-to-one basis using a correspondence table of SOC to the battery voltage (battery voltage value Vbt) related to the secondary battery 17. Furthermore, the lower limit SOC is a concept that corresponds to one of the following: the reference lower limit voltage value Vlow, the noncritical lower limit voltage value Vlow_nl, or the critical lower limit voltage value Vlow_lim.

[0094] According to the secondary battery control system 11 based on the first perspective, when the State of Charge (SOC) acquired by the battery state acquisition unit (acquisition unit) 51 falls to the lower limit SOC, the generated power (supplied power) from the generator (power supply) 13 is controlled to be less than the required power from the load 15, thereby enabling timely and appropriate capacity recovery processing for the secondary battery 17.

[0095] The secondary battery control system 11 based on the second perspective is a secondary battery control system 11 based on the first perspective, The control device 19 has a function to control the generated power (power supply) related to the generator (power supply) 13. The control unit 73 has, as control modes, a normal operation control that prevents the SOC from falling below the lower limit SOC, and a capacity recovery control that prevents the generated power (supplied power) from the generator (power supply) 13 from falling below the required power from the load 15. The lower limit of SOC is set based on the reference lower limit of SOC (corresponding to the reference lower limit voltage value Vlow) such that the secondary battery 17 does not fall into an over-discharge state during normal operation control. The control unit 73 may also be configured to perform capacity recovery control, which reduces the generated power (supplied power) from the generator (power supply) 13 in relation to the requested power from the load 15 when the SOC falls to the lower limit SOC.

[0096] In the secondary battery control system 11 based on the second perspective, in the control device 19 which has the function of controlling the generated power (supplied power) related to the generator (power supply) 13, the control unit 73 performs the capacity recovery control which reduces the generated power (supplied power) related to the generator (power supply) 13 in relation to the power required by the load 15 when the SOC falls to the lower limit SOC.

[0097] According to the secondary battery control system 11 based on the second perspective, when the SOC falls to the lower limit SOC, the control unit 73 performs the capacity recovery control, which reduces the generated power (supplied power) from the generator (power supply) 13 relative to the power required by the load 15. Therefore, the effects of the secondary battery control system 11 based on the first perspective can be realized by using the function of controlling the generated power (supplied power) from the generator (power supply) 13.

[0098] The secondary battery control system 11 based on the third perspective is a secondary battery control system 11 based on the first perspective, The control device 19 has a function to control the power requirements for the load 15, The control unit 73 has, as control modes, a normal operation control that ensures the SOC does not fall below the lower limit SOC, and a capacity recovery control that ensures the power requested by the load 15 exceeds the power generated (power supplied) by the generator (power supply) 13. The lower limit of SOC is set based on the reference lower limit of SOC (corresponding to the reference lower limit voltage value Vlow) such that the secondary battery 17 does not fall into an over-discharge state during normal operation control. The control unit 73 may also be configured to perform capacity recovery control, which increases the power required by the load 15 relative to the generated power (supplied power) related to the generator (power supply) 13 when the SOC falls to the lower limit SOC.

[0099] In the secondary battery control system 11 based on the third perspective, in the control device 19 which has a function to control the power request related to the load 15, the control unit 73 performs the capacity recovery control which increases the power request related to the load 15 relative to the generated power (power supply) related to the generator (power supply) 13 when the SOC falls to the lower limit SOC.

[0100] According to the secondary battery control system 11 based on the third perspective, when the SOC falls to the lower limit SOC, the control unit 73 performs the capacity recovery control, which increases the power demanded by the load 15 relative to the generated power (supplied power) related to the generator (power supply) 13. Therefore, the effects of the secondary battery control system 11 based on the first perspective can be realized by using the function of controlling the power demanded by the load 15.

[0101] A secondary battery control system 11 based on the fourth perspective is a secondary battery control system 11 based on the second or third perspective, The aforementioned power supply is a generator 13. The generator state acquisition unit (acquisition unit) 61 provided in the control device 19 further acquires the surplus power generation capacity related to the generator 13, The control unit 73 is If, considering the power requirements of the load 15, the remaining power generation capacity of the generator 13 is deemed insufficient to recharge the secondary battery 17 to the lower limit SOC or higher after the execution of capacity recovery control, a configuration may be adopted in which a power shortage is assumed to occur and the SOC is controlled to exceed the lower limit SOC (normal operation control).

[0102] According to the secondary battery control system 11 based on the fourth perspective, if the control unit 73 determines that the surplus power generation capacity of the generator 13 is insufficient to recharge the secondary battery 17 to the lower limit SOC or higher after the execution of capacity recovery control, considering the power demands of the load 15, it will assume that a power shortage will occur and will control the system so that the SOC exceeds the lower limit SOC (normal operation control). In addition to the effects of the secondary battery control system 11 based on the second or third perspective, in cases where a power shortage can be assumed to occur with the surplus power generation capacity of the generator 13, it is possible to prevent unexpected shutdowns of the load 15.

[0103] A secondary battery control system 11 based on the fifth perspective is a secondary battery control system 11 based on the second or third perspective, The SOC may be configured to be controlled to be above a critical lower limit (corresponding to the critical lower limit voltage value Vlow_lim) SOC, taking into consideration the integrity of the secondary battery 17 during the capacity recovery control.

[0104] According to the secondary battery control system 11 based on the fifth perspective, the SOC is controlled to be above the critical lower limit (corresponding to the critical lower limit voltage value Vlow_lim) SOC, which takes into consideration the assurance of the health of the secondary battery 17 during the capacity recovery control. Therefore, in addition to the effects of the secondary battery control system 11 based on the second or third perspective, the health of the secondary battery 17 during capacity recovery control can be ensured.

[0105] The secondary battery capacity recovery method based on the sixth perspective is: A secondary battery control system 11 comprising a generator (power supply) 13, a secondary battery 17 connected to the generator 13 and a load 15, and a control device 19 that controls the charging and discharging of the secondary battery 17, wherein a secondary battery capacity recovery method is used when performing a capacity recovery process on the secondary battery 17, A process for obtaining the State of Charge (SOC), which is the battery state of the secondary battery 17, A control step is performed to control the generated power (supplied power) of the generator (power supply) 13 so that, when the acquired SOC falls to a lower limit SOC that defines the lower limit of the SOC related to the secondary battery 17, the generated power (supplied power) related to the generator (power supply) 13 becomes smaller than the required power related to the load 15. It is characterized by having the following features.

[0106] In the secondary battery capacity recovery method based on the sixth perspective, the acquisition step acquires the State of Charge (SOC), which is the battery state of the secondary battery 17. In the control step, when the SOC acquired in the acquisition step falls to the lower limit SOC, the generator 13 is controlled so that the generated power (supplied power) is less than the required power for the load 15.

[0107] In the secondary battery capacity recovery method based on the sixth perspective, the SOC obtained by the acquisition step is a concept equivalent to the battery voltage value Vbt. This is because the battery voltage value Vbt can be converted to SOC on a one-to-one basis using a correspondence table of SOC to the battery voltage (battery voltage value Vbt) related to the secondary battery 17. Furthermore, the lower limit SOC is a concept that corresponds to one of the following: the reference lower limit voltage value Vlow, the noncritical lower limit voltage value Vlow_nl, or the critical lower limit voltage value Vlow_lim.

[0108] According to the capacity recovery method based on the sixth perspective, when the SOC acquired in the acquisition step falls to the lower limit SOC, the control step controls the generated power (supplied power) from the generator (power supply) 13 to be less than the required power from the load 15, thereby enabling timely and appropriate capacity recovery processing for the secondary battery 17.

[0109] The secondary battery capacity recovery method based on the seventh perspective is: A method for restoring secondary battery capacity based on a sixth perspective, The control process further includes, as a control mode, a normal operation control process that ensures the SOC does not fall below the lower limit SOC, and a capacity recovery control process that ensures the power requested by the load 15 exceeds the power generated (power supplied) by the generator (power supply) 13. The lower limit of SOC may be set based on a standard lower limit of SOC such that the secondary battery 17 does not fall into an over-discharge state during the normal operation control process.

[0110] In the secondary battery capacity recovery method based on the seventh perspective, the normal operation control step is a concept corresponding to the function of the normal operation control unit 75. Furthermore, the capacity recovery control step is a concept corresponding to the function of the capacity recovery control unit 77.

[0111] According to the secondary battery capacity recovery method based on the seventh perspective, the control step further comprises the normal operation control step and the capacity recovery control step as control modes, and the lower limit SOC is set based on the reference lower limit of SOC such that the secondary battery 17 does not fall into an over-discharge state during the normal operation control step. Therefore, in addition to the effects of the secondary battery capacity recovery method based on the sixth perspective, it is possible to prevent the secondary battery 17 from falling into an over-discharge state during the normal operation control step.

[0112] [Other Embodiments] The embodiments and examples described above illustrate examples of the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these descriptions, as the present invention can be implemented in various forms without departing from its gist or main features.

[0113] Furthermore, it is possible to replace some of the configurations of the embodiments described here with those of other embodiments, and even to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace some of the configurations of each embodiment with those of other embodiments.

[0114] Furthermore, the control lines and information lines shown are those deemed necessary for explanatory purposes, and not all control lines and information lines are necessarily shown in the actual product. In reality, it can be assumed that almost all components are interconnected.

[0115] The secondary battery 17 covered by the present invention is not limited to a single cell, but may also be a secondary battery module in which multiple cells are connected, or a secondary battery pack in which multiple secondary battery modules are interconnected.

[0116] The generator 13 according to the present invention is not limited to a generator that generates electricity by burning fuel, such as a diesel generator. A wide range of "power sources" including a generator that generates electricity by electrochemically reacting fuel, such as a fuel cell, or other energy storage devices such as secondary batteries, may be used as long as they can supply power to the secondary battery 17.

[0117] The control device 19 according to the present invention is not limited to the configuration shown in Figure 4, and any configuration that can determine whether or not capacity recovery control is necessary based on the state of the secondary battery 17 and the generator 13, and the power request related to the load 15, and selectively execute normal operation control or capacity recovery control is acceptable. Furthermore, all of the functional units shown in the control device 19 do not need to be integrated, and a configuration in which some functions are processed on a separate server located spatially away by communication functions may be adopted.

[0118] Finally, each component, function, processing unit, etc., provided in the secondary battery control system 11 according to the embodiment of the present invention may be implemented in hardware, either partially or entirely, by designing them as an integrated circuit, for example. Alternatively, each of the above-mentioned components, functions, processing units, etc., may be implemented in software by having a processor interpret and execute a program that implements each function. Information such as programs, tables, and files that implement each function can be stored in a recording device such as memory, a hard disk, or an SSD (Solid State Drive), or in a recording medium such as an IC card, an SD card, or a DVD (Digital Versatile Disk). [Explanation of symbols]

[0119] 11. Secondary battery control system 13 Generator (power supply) 15 load 17 Secondary battery 19 Control device 51 Battery status acquisition unit (acquisition unit) 53 Battery status determination unit 55 Storage section 57 Battery State Calculation Unit 61 Generator status acquisition unit (acquisition unit) 63 Generator state calculation unit 71 Capacity recovery control determination unit 73 Control Unit 75 Normal Operation Control Unit 77 Capacity Recovery Control Unit

Claims

1. A secondary battery control system comprising a power supply, a secondary battery connected to the power supply and the load, and a control device for controlling the charging and discharging of the secondary battery, The aforementioned power supply has the function of supplying power to the secondary battery, The secondary battery has the function of being charged by receiving power supplied from the power supply and being discharged by outputting the required power from the load. The control device is An acquisition unit that acquires the State of Control (SOC), which is the battery state of the secondary battery, When the SOC acquired by the acquisition unit falls to a lower limit SOC that defines the lower limit of the SOC related to the secondary battery, the control unit controls the power supply related to the power supply to become smaller than the power required for the load, A secondary battery control system characterized by being configured with the following:

2. A secondary battery control system according to claim 1, The control device has a function to control the power supply output related to the power supply, The control unit has, as control modes, a normal operation control that ensures the SOC does not fall below the lower limit SOC, and a capacity recovery control that ensures the power supply output related to the power supply falls below the required power related to the load. The aforementioned lower limit of SOC is set based on the reference lower limit of SOC such that the secondary battery does not fall into an over-discharge state during normal operation control. The control unit performs the capacity recovery control, which reduces the power supplied by the power supply in relation to the power requested by the load, when the SOC falls to the lower limit SOC. A secondary battery control system characterized by the following features.

3. A secondary battery control system according to claim 1, The control device has a function to control the power requirements for the load, The control unit has, as control modes, a normal operation control that ensures the SOC does not fall below the lower limit SOC, and a capacity recovery control that ensures the power required for the load exceeds the power supply output of the power supply. The aforementioned lower limit of SOC is set based on the reference lower limit of SOC such that the secondary battery does not fall into an over-discharge state during normal operation control. When the SOC drops to the lower limit SOC, the control unit performs the capacity recovery control, which increases the power demanded by the load relative to the power supplied by the power supply. A secondary battery control system characterized by the following features.

4. A secondary battery control system according to claim 2 or 3, The aforementioned power supply is a generator, The acquisition unit provided in the control device further acquires the surplus power generation capacity related to the generator, The control unit, If, considering the power requirements of the load, the surplus power generation capacity of the generator is such that the secondary battery cannot be recharged to above the lower limit of SOC after the execution of capacity recovery control, the SOC is controlled to exceed the lower limit of SOC. A secondary battery control system characterized by the following features.

5. A secondary battery control system according to claim 2 or 3, The State of Control (SOC) is controlled to be above a critical lower limit SOC, taking into consideration the integrity of the secondary battery during the capacity recovery control. A secondary battery control system characterized by the following features.

6. A secondary battery control system comprising a power supply, a secondary battery connected to the power supply and a load, and a control device for controlling the charging and discharging of the secondary battery, wherein a secondary battery capacity recovery method is used when performing a capacity recovery process on the secondary battery, A step to obtain the State of Control (SOC), which is the battery state of the secondary battery, A control step is performed to control the power supply power supply so that, when the acquired SOC falls to a lower limit SOC that defines the lower limit of the SOC for the secondary battery, the power supply power supply for the power supply becomes smaller than the power required for the load. A method for restoring the capacity of a secondary battery, characterized by having the following features.

7. A method for restoring the capacity of a secondary battery according to claim 6, The control step further includes, as a control mode, a normal operation control step that ensures the SOC does not fall below the lower limit SOC, and a capacity recovery control step that ensures the power required for the load exceeds the power supply output of the power supply. The aforementioned lower limit of SOC is set based on the reference lower limit of SOC at which the secondary battery does not fall into an over-discharge state during the normal operation control process. A method for restoring the capacity of a secondary battery, characterized by the features described herein.

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