Battery management system and battery management method

Abstract

A battery management system and a battery management method are provided. A battery storage compartment (2) comprises: a battery group including a plurality of batteries; a power conversion device (AC / DC converter (22) and a DC / DC converter (23)) electrically connected between the plurality of batteries and a power system (5) and capable of bidirectional power conversion; and a server (20) that controls the operation of the power conversion device according to a DR request from the power system (5) to charge and discharge the plurality of batteries. The server (20) suppresses the charge and discharge of batteries of a smaller degree of deterioration than the charge and discharge of batteries of a larger degree of deterioration among the levels related to the degree of deterioration of the batteries. This ensures a high-level inventory of batteries.

Description

Technical Field

[0001] The present disclosure relates to a battery management system and a battery management method. Background Art

[0002] Japanese Patent Application Laid-Open No. 2018-205873 describes urging users of electric vehicles having batteries suitable for power storage systems to replace the batteries. Summary of the Invention

[0003] In recent years, the popularity of vehicles equipped with battery packs for driving has been rapidly increasing. Consequently, the number of used batteries collected and recycled as these vehicles are traded in, dismantled, and so on is increasing. From the perspective of promoting the Sustainable Development Goals (SDGs), it is desirable to use recycled used batteries to manufacture new battery packs and reuse the used batteries. The inventors have focused on the following issues that may arise when reusing used batteries.

[0004] Batteries are stored at logistics centers, etc., while awaiting utilization. Proper battery storage incurs costs. Furthermore, it can take a considerable amount of time (storage period) from the time recycled batteries are stored to the time they are shipped for utilization. Therefore, it is desirable to effectively utilize the battery storage period.

[0005] Consider rating batteries according to their degree of degradation. Depending on the intended use, the required rank may also differ. Therefore, there may be a rank with relatively high demand, and on the other hand, there may be a rank with relatively low demand. For the battery management system, it is hoped that a number of batteries corresponding to the demand for use will be secured as inventory for each rank. On the other hand, the battery management system cannot adjust what rank of batteries to be recovered from the market. In addition, during the storage period of the battery management system, the degradation of the battery will also progress, and the rank may be lowered as a result.

[0006] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to ensure a high-grade battery inventory.

[0007] (1) A battery management system according to one aspect of the present disclosure includes: a storage unit storing a plurality of batteries; a power conversion device electrically connected between the plurality of batteries stored in the storage unit and a power system, capable of bidirectional power conversion; and a control device that controls the operation of the power conversion device in accordance with a demand response request from the power system, thereby charging and discharging the plurality of batteries. The control device suppresses the charging and discharging of batteries with a lower degree of degradation compared to the charging and discharging of batteries with a higher degree of degradation among the levels of battery degradation.

[0008] In the configuration (1) above, the charge and discharge of batteries with a lesser degree of deterioration is suppressed compared to the charge and discharge of batteries with a more deteriorated degree. Therefore, the quality of batteries with a lesser degree of deterioration is maintained compared to batteries with a more deteriorated degree. As a result, a stock of high-quality batteries can be secured.

[0009] (2) When the charge and discharge amounts of the plurality of batteries in the more degraded level are less than the charge and discharge amount corresponding to the demand response request, the control device also charges and discharges the batteries in the less degraded level.

[0010] In the configuration of (2) above, it is possible to perform charging and discharging in accordance with a demand response request from the power system while maintaining the battery level at a low level of degradation.

[0011] (3) The battery management system further includes a switching device configured to switch between electrical connection and disconnection between the plurality of batteries and the power system. The control device controls the switching device so that batteries at a level that suppresses charging and discharging are electrically disconnected from the power system.

[0012] In the configuration of (3) above, the battery at the level where charging and discharging is suppressed is electrically disconnected from the power system. Therefore, the level of the battery at the level where charging and discharging is suppressed can be maintained more reliably.

[0013] (4) The control device makes the charge and discharge electric quantity of the battery of the level where charge and discharge are suppressed smaller than the charge and discharge electric quantity of the battery of the level different from the level where charge and discharge are suppressed within a predetermined period.

[0014] (5) The control device makes the charge and discharge frequency of the battery of the charge and discharge suppression level lower than the charge and discharge frequency of the battery of a level different from the charge and discharge suppression level.

[0015] (6) Another aspect of the present disclosure relates to a battery management method using a server. The method includes the step of causing the server to charge and discharge a plurality of batteries stored in a storage facility in response to a demand response request from the power system. The charging and discharging step includes the step of suppressing the charging and discharging of batteries with a lower degree of degradation compared to the charging and discharging of batteries with a higher degree of degradation among the levels of battery degradation.

[0016] According to the method of (6), similar to the configuration of (1), it is possible to ensure a stock of high-grade batteries.

[0017] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing one form of logistics of a battery pack in this embodiment.

[0019] Figure 2 This is a diagram showing an example of a situation in which used batteries are stored in a storage unit.

[0020] Figure 3 This is a flowchart showing an outline of the operation process for recycling used batteries.

[0021] Figure 4 This is a system configuration diagram showing the electrical structure of the battery storage compartment (cellar).

[0022] Figure 5 This is a diagram showing an example of the data structure of battery data.

[0023] Figure 6 This is a conceptual diagram for explaining an example of a method of suppressing the charge and discharge of a used battery in the present embodiment.

[0024] Figure 7 This is a conceptual diagram for explaining another example of a method of suppressing the charge and discharge of a used battery in the present embodiment.

[0025] Figure 8 This is a conceptual diagram for explaining another example of a method of suppressing the charge and discharge of a used battery in the present embodiment.

[0026] Figure 9 This is a flowchart showing a first example of a processing procedure related to charge and discharge suppression in this embodiment.

[0027] Figure 10 This is a flowchart showing a second example of the processing procedure related to charge and discharge suppression in this embodiment.

[0028] Figure 11 This is a flowchart showing a third example of the processing procedure related to charge and discharge suppression in this embodiment.

[0029] Figure 12 This is a functional block diagram of a server related to deterioration evaluation of used batteries.

[0030] Figure 13 This is a functional block diagram of a server related to power coordination between the battery storage tank and the power system. DETAILED DESCRIPTION

[0031] In the present disclosure and embodiments, battery charging and discharging means at least one of charging and discharging of the battery. That is, battery charging and discharging is not limited to both charging and discharging of the battery, and may be only charging of the battery or only discharging of the battery.

[0032] In the present disclosure, a battery pack includes a plurality of modules (also referred to as blocks or stacks). The modules may be connected in series or in parallel. Each module includes a plurality of battery cells (single cells).

[0033] Generally speaking, the "reuse" of battery packs is roughly divided into reuse, reassembly, and material recycling. In the case of reuse, the recycled battery pack undergoes necessary shipment inspections and is directly shipped as a reused product. In the case of reassembly, the recycled battery pack is temporarily disassembled into modules. And, the usable modules among the disassembled modules (or modules that become usable after performance recovery) are combined to manufacture a new battery pack. The newly manufactured battery pack undergoes shipment inspection and is shipped as a reassembled product. In contrast, in material recycling, renewable materials (resources) are taken out from each battery cell. The recycled battery pack will not be used as another battery pack.

[0034] In the embodiments described below, battery packs recovered from vehicles are temporarily disassembled into modules. Various processes are then performed on a module-by-module basis. In other words, in the following description, "reusable used batteries" refer to modules that can be reassembled. However, disassembly into modules is not essential. Depending on the battery pack's configuration or degree of deterioration, it may be possible to reuse the battery pack without disassembly into modules.

[0035] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are given the same reference numerals, and their description will not be repeated.

[0036] [Implementation Method]

[0037] Battery Logistics Model

[0038] Figure 1 This is a diagram showing one way of logistics of the battery pack in this embodiment. Figure 1 The logistics model shown is called a “battery logistics model.” The battery logistics model 100 includes a recycling company 1 , a battery storage warehouse 2 , a buyer 3 , a recycling plant 4 , a power system 5 , and a distributed energy resource (DER) 6 .

[0039] A recycling company 1 collects used battery packs (second-hand batteries 9) from a plurality of vehicles. The recycling company 1 may be a vehicle dealership (dealer) or a vehicle dismantling company. In this example, identification information (battery ID) is assigned to each second-hand battery 9 (see Figure 5 ). Therefore, in the battery logistics model 100, the battery ID can be used to identify the used battery 9, manage the data of the used battery 9 (battery data described later, etc.), and track the circulation path of the used battery 9.

[0040] The battery storage room 2 is a facility for properly managing the used batteries 9 collected by the recycling company 1, like a wine cellar storing wine bottles under temperature and humidity control. Figure 1 In the example shown, the battery storage warehouse 2 is located at a logistics base near a port. The battery storage warehouse 2 includes a server 20 that manages data related to used batteries 9 and multiple storage units 21. Furthermore, the battery storage warehouse 2 corresponds to the "battery management system" referred to in this disclosure. The storage units 21 correspond to the "storage warehouse" referred to in this disclosure. The batteries stored in the battery storage warehouse 2 are not limited to used batteries and may also include new batteries.

[0041] Figure 2 2 is a diagram showing an example of a situation in which used batteries 9 are stored in the storage unit 21. Figure 2 As shown, multiple storage units 21 are located within the battery storage facility 2. Each of the multiple storage units 21 is configured to store a large number of used batteries 9. While details will be described later, in this embodiment, the battery storage facility 2 performs a degradation evaluation test on each of the used batteries 9 stored in the storage units 21. Furthermore, based on the results of the degradation evaluation test, the battery storage facility 2 determines whether each used battery 9 can be reused (i.e., whether it is suitable for reuse).

[0042] return Figure 1 Buyers 3 sell used batteries 9 that have been determined by battery storage 2 to be reusable. Buyers 3 may include sales stores 31 that sell used batteries 9 as vehicle batteries and users 32 that use them as stationary batteries in factories, buildings, etc. Buyers 3 may also include sales stores 33 that sell used batteries 9 as supplies (replacement parts for maintenance and repair).

[0043] The recycling plant 4 recycles materials for regenerating the used batteries 9 determined to be unusable by the battery storage 2 as raw materials for other products.

[0044] The power system 5 is a power grid consisting of power plants and power transmission and distribution facilities. In this embodiment, the power company serves as both a power generation provider and a power transmission and distribution provider. The power company is equivalent to a general power transmission and distribution provider and also acts as the manager of the power system 5, maintaining and managing the system. A service provider server 50 is installed within the power system 5. Service provider server 50 belongs to the power company and manages the supply and demand of power within the power system 5. Server 20 and service provider server 50 are configured to enable bidirectional communication.

[0045] DER 6 is a relatively small-scale power facility installed at a distribution center (or its surrounding area) where the battery storage 2 is installed, and capable of transferring power to and from the battery storage 2. DER 6 includes, for example, power generation DER and power storage DER.

[0046] Power generation DERs can include naturally fluctuating power sources and generators. Naturally fluctuating power sources are power generation equipment whose power output fluctuates according to meteorological conditions. Figure 1 While solar power generation equipment (solar panels) is illustrated in the example, naturally fluctuating power sources may also replace solar power generation equipment or include wind power generation equipment in addition to solar power generation equipment. Meanwhile, generators are power generation equipment that is independent of meteorological conditions. Generators may include steam turbine generators, gas turbine generators, diesel engine generators, gas engine generators, biomass generators, and stationary fuel cells. Generators may also include cogeneration systems that utilize heat generated during power generation.

[0047] The electric storage type DER may include an electric storage system and a heat storage system. The electric storage system is a stationary electric storage device that stores electric power generated by a naturally fluctuating power source or the like. The electric storage system may also be a power-to-gas (P2G) device that uses electric power to produce gaseous fuels (hydrogen, methane, etc.). The heat storage system includes a heat storage tank disposed between the heat source and the load, and is configured to temporarily store the liquid medium in the heat storage tank in an insulated state. By using a heat storage system, the generation and consumption of heat can be staggered in time. Therefore, for example, it is possible to consume electric power at night, store the heat generated by operating the heat source machine in the heat storage tank, and consume the heat during the day for air conditioning.

[0048] Thus, used batteries 9 collected by recycling company 1 are stored in battery storage bin 2 while awaiting shipment to buyer 3 or recycling plant 4. However, using battery storage bin 2 to properly store used batteries 9 also incurs maintenance costs (operating costs). Furthermore, the period from storage of collected used batteries 9 to shipment to buyer 3 or recycling plant 4 may require a considerable amount of time. Therefore, it is desirable to effectively utilize the storage period of used batteries 9 in battery storage bin 2.

[0049] In this embodiment, the battery storage warehouse 2 functions as a virtual power plant (VPP) in addition to being a storage location for used batteries 9. This allows the charging and discharging of used batteries 9 to serve as both a deterioration assessment for used batteries 9, which determines their reuse, and an adjustment to the power supply and demand balance of the power system 5 utilizing them. As a result, the battery storage warehouse 2 seamlessly integrates the storage of used batteries 9, the deterioration assessment of used batteries 9, and the adjustment of the power supply and demand balance using used batteries 9.

[0050] <Used Battery Recycling Process>

[0051] Figure 3 This is a flowchart showing an outline of an operation process for recycling used batteries 9. First, used batteries 9 collected by a recycling company 1 are delivered to a battery storage room 2 (S1).

[0052] In this embodiment, the server 20 performs a degradation evaluation test (performance check) on each of the used batteries 9 while the batteries are stored in the storage unit 21 (S2). The server 20 evaluates the degree of degradation of each used battery 9 based on electrical characteristics such as full charge capacity and internal resistance (e.g., AC impedance). Based on the results of the degradation evaluation test, the server 20 determines whether each used battery 9 is reusable (S3).

[0053] In this embodiment, the used battery 9 is rated based on the results of the degradation evaluation test (more specifically, the results of the measurement of the full charge capacity). Figure 2 As shown, recyclable used batteries 9 are ranked into four levels: S, A, B, and C, in descending order of full charge capacity. This allows the transaction price of used batteries 9 to be set in association with the level, ensuring the quality of used batteries 9 based on the level. This allows used batteries 9 that have passed through the battery storage compartment 2 to be smoothly circulated in the market. Furthermore, used batteries 9 with a full charge capacity below a specified value are ranked lower than C (denoted as Re) and are directed to material recycling.

[0054] When it is determined that the battery can be reused ("Yes" in S3), the operation process enters the performance recovery process (S4). In the performance recovery process, a process for recovering the performance of the used battery 9 (performance recovery process) is implemented. For example, by overcharging the used battery 9, the full charge capacity of the used battery 9 can be restored. However, the performance recovery process can also be omitted. In addition, the performance recovery process can be implemented for used batteries 9 whose degradation degree is large (performance is greatly reduced) as a result of the degradation evaluation test. On the other hand, the performance recovery process is not implemented for used batteries 9 whose degradation degree is small (performance is not greatly reduced).

[0055] Next, a new battery pack is manufactured (reassembled) using the used batteries 9 whose performance has been restored through the performance restoration process (S5). The used batteries 9 used in the battery pack assembly are generally used batteries 9 that have undergone the performance restoration process, but may also include used batteries 9 that have omitted the performance restoration process or new batteries (new modules). The battery pack is then sold and shipped to the buyer 3 (S6).

[0056] If the degradation evaluation test determines that the used battery 9 is not recyclable ("No" in S3), the used battery 9 is transported to the recycling plant 4 (S7). In the recycling plant 4, the used battery 9 is disassembled and recycled.

[0057] Thus, from the time the used batteries 9 are collected by the recycling company 1 until they are delivered to the buyer 3 or recycling plant 4, they are stored in the battery storage silo 2, during which time a degradation evaluation test is performed. During the degradation evaluation test, the used batteries 9 are charged and discharged to measure their electrical characteristics, such as their full charge capacity. In this embodiment, this charging and discharging utilizes the power exchanged between the battery storage silo 2 (and the DER 6) and the power grid 5. Thus, the battery storage silo 2 functions as a VPP (or one of the DERs), contributing to load balancing on the power grid 5. More specifically, during periods when the power grid 5 has a surplus supply to meet demand, the battery storage silo 2 absorbs this excess power by charging the used batteries 9. On the other hand, when the power grid 5 has a shortage of supply to meet demand, the battery storage silo 2 alleviates the shortage by discharging the surplus power from the used batteries 9.

[0058] However, the battery storage compartment 2 need not be configured to contribute to both absorbing excess power in the power grid 5 and alleviating power shortages. The battery storage compartment 2 may also be configured to contribute to only one of absorbing excess power or alleviating power shortages. For example, the battery storage compartment 2 may be configured to charge the remaining power in the power grid 5 to the used battery 9, while discharging power from the used battery 9 to a destination other than the power grid 5. For example, the discharge destination of the used battery 9 may be only the DER 6.

[0059] <Battery storage compartment system configuration>

[0060] Figure 4 2 is a system configuration diagram showing the electrical structure of the battery storage compartment 2. The battery storage compartment 2 includes, for example, a storage unit 21, an AC / DC converter 22, a DC / DC converter 23, and a server 20. Figure 4 In the figure, for the convenience of paper, only one storage unit 21 is shown. Figure 2 As shown, a typical battery storage compartment 2 includes a plurality of storage units 21 .

[0061] The storage unit 21 stores a plurality of used batteries 9. Figure 4 In the example, multiple used batteries 9 are connected in parallel. However, this is merely an example, and the connection method of multiple used batteries 9 is not particularly limited. Multiple used batteries 9 can be connected in series, or a combination of series and parallel connections can be used. Storage unit 21 includes a voltage sensor 211, a current sensor 212, and a relay 213.

[0062] The voltage sensor 211 detects the voltage VB of the used battery 9 and outputs the detected value to the server 20. The current sensor 212 detects the current IB of the used battery 9 during charging and discharging and outputs the detected value to the server 20. Furthermore, when temperature is used to evaluate the deterioration of the used battery 9, the storage unit 21 may also include a temperature sensor (not shown). Alternatively, each sensor may be a sensor provided by the used battery 9.

[0063] Relay 213 includes, for example, a first relay electrically connected to the positive electrode side of used battery 9 and a second relay electrically connected to the negative electrode side of used battery 9. Relay 213 is configured to switch between electrical connection and disconnection between used battery 9 and power system 5. This allows any used battery 9 to be electrically disconnected and removed from storage unit 21 even while other used batteries 9 are being charged or discharged. Relay 213 corresponds to the "switching device" referred to in this disclosure.

[0064] AC / DC converter 22 is electrically connected between power grid 5 and DC / DC converter 23. AC / DC converter 22 is configured to perform bidirectional power conversion operations for charging and discharging used batteries 9 stored in the storage unit in accordance with control commands (charge and discharge commands) from server 20. More specifically, AC / DC converter 22 converts AC power supplied from power grid 5 into DC power for charging used batteries 9. Furthermore, AC / DC converter 22 converts DC power discharged from used batteries 9 into AC power for supply to power grid 5.

[0065] DC / DC converter 23 is electrically connected between AC / DC converter 22 and storage unit 21, and also electrically connected between DER 6 and storage unit 21. Like AC / DC converter 22, DC / DC converter 23 is configured to perform bidirectional power conversion in accordance with control commands (charge and discharge commands) from server 20. DC / DC converter 23 can charge DC power from AC / DC converter 22 and / or DER 6 into secondary battery 9, and discharge DC power stored in secondary battery 9 into AC / DC converter 22 and / or DER 6.

[0066] The server 20 includes a processor such as a CPU (Central Processing Unit), memory such as ROM (Read Only Memory) and RAM (Random Access Memory), and input / output ports (not shown) for inputting and outputting various signals. The server 20 performs various control operations based on signals received from various sensors and programs and maps stored in the memory. The server 20 includes a battery data storage unit 201, a degradation evaluation unit 202, a power adjustment unit 203, a timing adjustment unit 204, and a display unit 205.

[0067] The battery data storage unit 201 stores battery data used to manage the used batteries 9 in the battery storage compartment 2 .

[0068] Figure 5This is a diagram showing an example of a data structure for battery data. Battery data is stored, for example, in a mapping format. Battery data includes, for example, identification information (battery ID) for identifying a used battery 9, the model of the used battery 9, the date of manufacture, the current SOC (State of Charge), the full charge capacity, the level, the date and time of degradation evaluation (the latest date and time when the degradation evaluation test was performed), and the storage location (identification information of the storage unit where the used battery 9 is stored) as parameters. In addition, battery data may also include parameters other than those listed above (such as the internal resistance of the used battery 9, the indicator ΣD indicating the bias in the salt concentration distribution in the electrolyte of the used battery 9, etc.).

[0069] Refer again Figure 4 The degradation evaluation unit 202 performs a degradation evaluation test on the used battery 9 based on the voltage VB and the current IB detected by the voltage sensor 211 and the current sensor 212 during the charge and discharge of the used battery 9. Figure 12 An example of this evaluation method will be described. The degradation evaluation unit 202 performs a rating on the used battery 9 based on the results of the degradation evaluation test.

[0070] The power adjustment unit 203 adjusts the power between the battery storage 2 (and DER 6) and the power system 5. More specifically, the server 20 selects the second-hand battery 9 in response to the request from the business server 50 (see Figure 1 The power adjustment unit 203 outputs instructions to the relay 213, the AC / DC converter 22, and the DC / DC converter 23 so that the selected used battery 9 is charged and discharged. Figure 13 An example of this control method will be described.

[0071] The timing adjustment unit 204 adjusts the timing of the degradation evaluation test of the used battery 9 performed by the degradation evaluation unit 202 and the timing of the power adjustment between the battery storage compartment 2 and the power system 5 performed by the power adjustment unit 203. More specifically, the timing adjustment unit 204 performs timing adjustment so that the degradation evaluation test of the used battery 9 is performed in accordance with the timing of the DR performed by the battery storage compartment 2 in response to the DR request from the business server 50. In addition, the degradation evaluation test performed in accordance with the DR of the battery storage compartment 2 is not limited to the degradation evaluation test of the used battery 9, and performance recovery processing may also be performed on the basis of the degradation evaluation test (see Figure 3 S4).

[0072] The display unit 205 displays the battery data (see Figure 5 In addition, the display unit 205 displays the progress and results of the degradation assessment test conducted by the degradation assessment unit 202. This allows the administrator to understand the status of the degradation assessment test. Furthermore, the display unit 205 displays the status of the used battery 9 selected for charging and discharging by the power adjustment unit 203. This allows the administrator to understand the status of the power adjustment between the battery storage compartment 2 and the power system 5.

[0073] The server 20 corresponds to the “control device” in the present disclosure. The AC / DC converter 22 and the DC / DC converter 23 correspond to the “power conversion device” in the present disclosure.

[0074] <Stock Guarantee>

[0075] The required grade varies depending on the purpose of reuse, etc. Therefore, there may be a grade with relatively high demand, and on the other hand, there may be a grade with relatively low demand. It is hoped that the battery storage compartment 2 will ensure a quantity of used batteries 9 corresponding to the demand for reuse for each grade as inventory. On the other hand, it is impossible to adjust what grade of used batteries 9 to be collected from the market on the side of the battery storage compartment 2. In addition, it is possible that the deterioration of the used batteries 9 will progress during the storage period of the battery storage compartment 2, thereby reducing the grade. In particular, in the battery storage compartment 2, each used battery 9 is repeatedly charged and discharged for power adjustment with the power system 5, and therefore, the deterioration of the used batteries 9 is easy to progress.

[0076] Therefore, in this embodiment, the server 20 suppresses the charging and discharging of used batteries 9 with relatively low levels of deterioration compared to the charging and discharging of used batteries 9 with relatively high levels of deterioration. This maintains the quality of used batteries 9 with low levels of deterioration compared to used batteries 9 with high levels of deterioration. As a result, a stock of high-quality used batteries 9 can be secured.

[0077] Figure 6 This is a conceptual diagram for explaining an example of a method of suppressing the charge and discharge of the used battery 9 in the present embodiment. Figure 7 This is a conceptual diagram for explaining another example of a method of suppressing the charge and discharge of the used battery 9 in the present embodiment. Figure 8 This is a conceptual diagram for explaining another example of a method for suppressing the charge and discharge of the used battery 9 in this embodiment. Figures 6 to 8 In FIG. 5 , the horizontal axis represents elapsed time, and the vertical axis represents the electric power charged and discharged from the battery storage compartment 2 (used battery 9 ) to the electric power system 5 .

[0078] like Figure 6As shown, the charge and discharge amount (charge and discharge amount) of the used battery 9 of grade S and A, which are relatively less deteriorated grades, within a predetermined period can be made smaller than the charge and discharge amount within a predetermined period of the used battery 9 of grade B and C, which are relatively more deteriorated grades (first control). Here, the method of reducing the charge and discharge amount within a predetermined period is not limited to the method of adjusting the size (e.g., peak value) of the charge and discharge power (see Figure 6 ), or Figure 7 The length of the charge and discharge period can be adjusted as shown. It is also possible to adjust both the size of the charge and discharge power and the length of the charge and discharge period. Figure 8 As shown, the charge and discharge frequency of used batteries 9 in grades S and A, which are relatively less degraded, can be reduced compared to the charge and discharge frequency of used batteries 9 in grades B and C, which are relatively more degraded (second control). Although not shown, it is also possible to suppress both the charge and discharge amount and the charge and discharge frequency of used batteries 9 in grades S and A, which are relatively less degraded, compared to used batteries 9 in grades more degraded. In other words, the first and second controls can be used in combination.

[0079] <Charge and discharge suppression process>

[0080] Figure 9 This is a flowchart illustrating a first example of a processing procedure related to charge and discharge suppression in this embodiment. This flowchart (and other flowcharts described below) are called and executed by a main routine (not shown) when predetermined conditions are met. Each step is implemented by software processing on server 20, but can also be implemented by hardware (circuitry) configured within server 20. Hereinafter, steps are abbreviated as S.

[0081] In S12, the server 20 calculates the amount of electricity required to adjust the power between the battery storage compartment 2 and the power system 5 using the battery storage compartment 2. Hereinafter, this amount of electricity will be referred to as the battery storage compartment adjustment amount, also recorded as kWh (bat). Figure 10 An example of a method for calculating the battery storage compartment adjustment amount kWh (bat) will be described in detail.

[0082] In S13, the server 20 determines whether the total amount of electricity that can be charged and discharged using all the used batteries 9 has a margin relative to the battery storage compartment adjustment capacity kWh(bat). If there is no margin, that is, if the battery storage compartment adjustment capacity kWh(bat) is greater than the amount of electricity that can be charged and discharged using all the used batteries 9 ("No" in S13), the server 20 requests that all the used batteries 9 be charged and discharged in order to bring the amount of electricity charged and discharged in the battery storage compartment 2 close to the battery storage compartment adjustment capacity ΔkWh(bat). Therefore, the server 20 charges and discharges all the used batteries 9 (S19).

[0083] On the other hand, when there is a margin, that is, when the battery storage bin adjustment amount kWh (bat) is smaller than the amount of electricity that can be charged and discharged using all the used batteries 9 ("Yes" in S13), the battery storage bin adjustment amount ΔkWh (bat) can be satisfied even if all the used batteries 9 are not charged and discharged. In this case, the server 20 determines the charge and discharge amount and charge and discharge frequency of each used battery 9 according to the level (S14). Specifically, the server 20 sets the level with a relatively small degree of deterioration (in Figure 6 In the example of S and A grades, the charge and discharge amount of the used battery 9 is determined to be smaller than the charge and discharge amount of the used battery 9 of a grade with a relatively large degree of deterioration (grade B and C grades).

[0084] Figure 10 This is a flowchart showing a second example of the processing procedure related to charge and discharge suppression in this embodiment. The processing of S22, S23, and S29 are respectively Figure 9 The processing of S12, S13, and S19 shown in FIG. 1 is the same, so the description thereof will not be repeated. Figure 10 As shown, the server 20 may determine the charge and discharge frequency of the used battery 9 of a relatively small degree of deterioration to be lower than the charge and discharge frequency of the used battery 9 of a relatively large degree of deterioration ( S24 ).

[0085] In this way, by reducing the charge and discharge amount and frequency of used batteries 9 used for power adjustment for relatively less degraded batteries 9 compared to used batteries 9 with more degraded batteries 9, degradation associated with charging and discharging can be suppressed. This maintains the quality of used batteries 9 with less degraded batteries 9 compared to used batteries 9 with more degraded batteries 9. As a result, a sufficient inventory of high-quality used batteries 9 can be secured.

[0086] Figure 11 This is a flowchart showing a third example of the processing procedure related to charge and discharge suppression in this embodiment. Figure 9 The processes of S12, S13, and S19 are identical and therefore will not be described again. If the total amount of electricity that can be charged and discharged using all the used batteries 9 is sufficient for the battery storage compartment adjustment kWh (bat) ("YES" in S33), the server 20 proceeds to S34.

[0087] In S34, for each used battery 9 with a relatively low degree of degradation, the SOC of the used battery 9 is determined to be within a predetermined SOC range. This SOC range is the SOC range in which degradation of the used battery 9 progresses slowly and is predetermined based on the characteristics of the used battery 9. Generally speaking, when the SOC of a secondary battery is excessively high (e.g., exceeding 80%) or excessively low (e.g., less than 20%), degradation of the secondary battery is likely to progress. Therefore, it is desirable to have an intermediate SOC range (e.g., an SOC range of 40% to 60%).

[0088] When the SOC of a used battery 9 among the used batteries 9 of grade S and A with relatively small degree of deterioration is within the SOC range where degradation progresses slowly ("Yes" in S34), the server 20 disconnects the relay 213 corresponding to the used battery 9 so that the used battery 9 is electrically disconnected from the power system 5 (S35).

[0089] Furthermore, if the number of used batteries 9 electrically disconnected from the power system 5 is excessive, the amount of electricity charged or discharged from the battery storage compartment 2 may be insufficient for the battery storage compartment adjustment kWh (bat). Therefore, it is desirable that the server 20 consider the battery storage compartment adjustment kWh (bat) when controlling the relay 213. In other words, it is desirable that the server 20 adjust the number of used batteries 9 electrically disconnected from the power system 5 so that the number of used batteries 9 required to meet the battery storage compartment adjustment kWh (bat) remains electrically connected to the power system 5.

[0090] In S36, the server 20 adjusts power flow with the power system 5 by charging and discharging the remaining used batteries 9 whose relay 213 is closed, namely, the remaining used batteries 9 (used batteries 9 with a SOC outside the SOC range where degradation progresses slowly) among the used batteries 9 with relatively low levels of deterioration (S and A grades) that remain electrically connected to the power system 5, and the used batteries 9 with relatively high levels of deterioration (B and C grades). Furthermore, used batteries 9 are more susceptible to degradation at higher temperatures. Therefore, the server 20 may impose certain limits on the charge and discharge current to prevent the used batteries 9 from excessively heating due to heat generation associated with charging and discharging.

[0091] In this way, the used battery 9, which has been electrically disconnected from the power system 5 by opening relay 213, is not used for charging and discharging for power regulation, thereby suppressing degradation associated with charging and discharging. Furthermore, the SOC of the used battery 9, which has been electrically disconnected from the power system 5, is maintained within an SOC range where degradation progresses slowly. This also suppresses degradation during storage that is not caused by charging and discharging (so-called aging or material degradation).

[0092] In addition, the S34 process can also be applied to Figure 9 and / or Figure 10 When the SOC of the used battery 9 is within the SOC range where degradation progresses slowly, the server 20 can reduce the charge and discharge amount of the used battery 9 of a relatively small degree of degradation and reduce the charge and discharge frequency.

[0093] In addition, about Figures 9 to 11 In any example, the server 20 may suppress the charge and discharge of a used battery 9 for which a buyer has been determined, compared to the charge and discharge of a used battery 9 of the same grade for which a buyer has not been determined. That is, the server 20 may suppress the charge and discharge of a used battery 9 for which a buyer has been determined, even if the used battery 9 is of a grade (e.g., Grade B or C) with a relatively high degree of deterioration. This can suppress the progression of deterioration of the used battery 9 during the storage period leading up to its sale, thereby preventing a decrease in grade from the time a buyer is determined.

[0094] <Degradation Evaluation>

[0095] Figure 12 This is a functional block diagram of server 20 (degradation assessment unit 202) related to degradation assessment of used batteries 9. For simplicity, the following description focuses on a single used battery 9. However, in practice, if there are multiple used batteries 9 that have not undergone degradation assessment, the same process can be performed simultaneously on all of them. Degradation assessment unit 202 includes a current integration unit 71, an OCV (open circuit voltage) calculation unit 72, an SOC change calculation unit 73, a full charge capacity calculation unit 74, and a rating unit 75.

[0096] Based on the current IB detected by the current sensor 212, the current integration unit 71 calculates the cumulative value (current integration amount) ΔAh (unit: Ah) of the current charged and discharged by the used battery 9 during the period from the start condition of current integration to the end condition. In this embodiment, as described above, the used battery 9 is charged and discharged in response to a DR request from the business server 50, and the current flowing during the DR is integrated. More specifically, when the DR is increased (a request to increase power demand), the used battery 9 is charged to increase the power demand of the battery storage compartment 2, and the charging current at that time is integrated. On the other hand, when the DR is decreased, the used battery 9 is discharged to reduce the power demand of the battery storage compartment 2, and the discharge current at that time is integrated. The current integration unit 71 outputs the calculated current integration amount ΔAh to the full charge capacity calculation unit 74.

[0097] The OCV calculation unit 72 calculates the OCV of the used battery 9 at the start of current integration and the OCV of the used battery 9 at the end of current integration. The OCV can be calculated according to the following formula (1), for example.

[0098] OCV=VB-ΔVp-IB×R···(1)

[0099] In formula (1), the internal resistance of the used battery 9 is expressed as R, and the polarization voltage is expressed as Vp. At the start of current integration (immediately before charging or discharging), the current IB = 0. Furthermore, if the used battery 9 is left uncharged or discharged before current integration begins, the polarization voltage Vp can be approximated to be 0. Therefore, the OCV at the start of current integration can be calculated based on the voltage VB detected by the voltage sensor 211. On the other hand, the internal resistance R can be determined based on the relationship between the voltage VB and the current IB (Ohm's law). Furthermore, if the used battery 9 is charged or discharged at a constant current, the polarization voltage Vp can also be determined based on the current IB detected by the current sensor 212 by previously measuring the relationship between the current and the polarization voltage Vp. Therefore, the OCV of the used battery 9 at the end of current integration can also be calculated based on the voltage VB and the current IB. The OCV calculation unit 72 outputs the two calculated OCVs to the SOC change calculation unit 73.

[0100] The SOC change calculation unit 73 calculates the SOC change ΔSOC of the used battery 9 from the start to the end of current integration based on the two OCVs. The SOC change calculation unit 73 pre-exists a characteristic curve (OCV-SOC curve) showing the SOC dependency of OCV. Therefore, by referring to the OCV-SOC curve, the SOC change calculation unit 73 can read the SOC corresponding to the OCV at the start of current integration and the SOC corresponding to the OCV at the end of current integration, and calculate the difference between these SOCs as ΔSOC. The SOC change calculation unit 73 outputs the calculated ΔSOC to the full charge capacity calculation unit 74.

[0101] The full charge capacity calculation unit 74 calculates the full charge capacity C of the used battery 9 based on ΔAh from the current integration unit 71 and ΔSOC from the SOC change calculation unit 73. Specifically, the full charge capacity C of the used battery 9 can be calculated using the following equation (2), where the ratio of ΔAh to ΔSOC is equal to the ratio of the full charge capacity C to ΔSOC = 100%. Furthermore, since the full charge capacity C0 in the initial state is known based on the specifications of the used battery 9, the full charge capacity calculation unit 74 may further calculate the capacity maintenance rate Q (Q = C / C0) based on the full charge capacity C. The full charge capacity calculation unit 74 outputs the calculated full charge capacity C to the rating unit 75.

[0102] C=ΔAh / ΔSOC×100···(2)

[0103] The rating unit 75 rates the used battery 9 based on the full charge capacity C. The rating unit 75 can record the rating date and time as the degradation evaluation date and time in the battery data (see Figure 5 ).

[0104] The grade of the used battery 9 is displayed on the display unit 205 along with the battery ID, storage location, etc. of the used battery 9. Thus, upon receiving a purchase request for used batteries 9 from the buyer 3, an operator working in the battery storage compartment 2 can remove used batteries 9 of the grade that meets the buyer 3's request from the storage location. By properly removing the sold used batteries from the storage unit 21, it is possible to prevent the storage unit 21 from running out of space.

[0105] The above-described method for calculating the full charge capacity C is merely an example. Any method can be used to calculate the full charge capacity C, as long as it uses the voltage VB and current IB detected during the charging and discharging of the used battery 9. Furthermore, the rating unit 75 may determine the rank of the used battery 9 based on other characteristics (such as the internal resistance R of the used battery 9 or an indicator ΣD indicating the concentration variation of the electrolyte in the lithium-ion battery) instead of or in addition to the full charge capacity C. Furthermore, the rating unit 75 may determine the rank of the used battery 9 based on the length of time the used battery 9 has been charged and discharged and / or the number of times the used battery 9 has been charged and discharged. Although this may result in slightly lower accuracy, the rating unit 75 may also determine the rank of the used battery 9 based on the time elapsed since the used battery 9 was manufactured. The rating unit 75 may also determine the rank of the used battery 9 based on a combination of the aforementioned factors (such as the full charge capacity C, internal resistance R, indicator ΣD, charge and discharge time, number of charge and discharge cycles, and time elapsed since manufacture).

[0106] <Power Adjustment>

[0107] Figure 13 This is a functional block diagram of server 20 (power adjustment unit 203) related to power adjustment between battery storage 2 and power grid 5. For ease of understanding, this example assumes that DER 6 is a power-generating DER (specifically, a naturally fluctuating power source such as a solar power generation facility). Power adjustment unit 203 includes an overall adjustment amount calculation unit 81, a DER adjustment amount calculation unit 82, a battery storage adjustment amount calculation unit 83, a used battery selection unit 84, a conversion operation unit 85, and a command generation unit 86.

[0108] Total adjustment amount calculation unit 81 receives a DR request from the operator's server 50 and calculates the total amount of electricity required for power adjustment using battery storage compartment 2 and DER 6 during a predetermined period (e.g., 30 minutes). This amount of electricity is hereinafter referred to as the total adjustment amount, also referred to as kWh (total). Total adjustment amount calculation unit 81 outputs the calculated kWh (total) to battery storage compartment adjustment amount calculation unit 83.

[0109] DER adjustment calculation unit 82 communicates with each DER 6 to obtain the operating status of each DER 6 (more specifically, the estimated amount of electricity generated by each DER 6 during a predetermined period). This amount of electricity is hereinafter referred to as DER adjustment, also expressed as kWh(DER). DER adjustment calculation unit 82 outputs the obtained kWh(DER) to battery storage compartment adjustment calculation unit 83.

[0110] The battery storage compartment adjustment amount calculation unit 83 calculates the amount of electricity required to adjust the power in the battery storage compartment 2 based on the kWh(total) from the total adjustment amount calculation unit 81 and the kWh(DER) from the DER adjustment amount calculation unit 82. This amount of electricity is hereinafter referred to as the battery storage compartment adjustment amount, also referred to as kWh(bat). For example, the battery storage compartment adjustment amount calculation unit 83 can calculate the difference between the two amounts of electricity as ΔkWh = kWh(total) - kWh(DER) as the battery storage compartment adjustment amount kWh(bat). The battery storage compartment adjustment amount calculation unit 83 outputs the calculated kWh(bat) to the used battery selection unit 84.

[0111] The used battery selection unit 84 determines the chargeable and dischargeable amount of each of the plurality of used batteries 9 stored in the plurality of storage units 21 (see Figure 5 Battery data). The used battery selection unit 84 selects a used battery for power adjustment from a large number of used batteries 9 based on the kWh (bat) from the battery storage compartment adjustment amount calculation unit 83. In the case of kWh (bat) > 0, the power shortage of the power system 5 is supplemented by discharging from the battery storage compartment 2. Therefore, the used battery selection unit 84 selects a number of used batteries 9 that can discharge an amount of electricity exceeding kWh (bat). On the other hand, in the case of kWh (bat) < 0, the surplus power of the power system 5 is absorbed by charging to the battery storage compartment 2. Therefore, the used battery selection unit 84 selects a number of used batteries 9 that can charge an amount of electricity exceeding kWh (bat) (absolute value). When selecting the used batteries 9, the used batteries 9 of a relatively large degree of deterioration are preferentially charged and discharged, and on the other hand, the used batteries 9 of a relatively small degree of deterioration are not charged and discharged as much as possible. Regarding this processing content, use Figures 9 to 11The used battery selection unit 84 outputs the selected used battery 9 and the amount of electricity allocated to each selected used battery 9 (the amount of electricity adjusted by each used battery 9 ) to the conversion calculation unit 85 .

[0112] The conversion calculation unit 85 calculates the amount of power charged and discharged by each used battery 9 selected by the used battery selection unit 84. More specifically, the conversion calculation unit 85 converts the amount of power (kWh) adjusted by each used battery 9 into power (kW) based on the remaining time for power adjustment for each used battery 9. For example, if the amount of power adjustment allocated to a used battery 9 is 10 kWh and the remaining time for power adjustment is 15 minutes, the calculated power is 10 kWh x (60 minutes / 15 minutes) = 40 kW. The conversion calculation unit 85 outputs the amount of power charged and discharged by each used battery 9 to the command generation unit 86.

[0113] Based on the calculation results of the conversion calculation unit 85, the command generation unit 86 generates charge and discharge commands for the AC / DC converter 22 and the DC / DC converter 23, and generates opening and closing commands for the relay 213. More specifically, the command generation unit 86 generates opening and closing commands so that the selected used battery 9 is electrically connected to the DC / DC converter 23, while the unselected used batteries 9 are electrically disconnected from the DC / DC converter 23. The command generation unit 86 generates charge and discharge commands so that the total amount of power allocated to the selected used battery 9 is charged and discharged.

[0114] In addition, confirm the record Figure 13 The power adjustment method shown is merely an example. In this example, it is assumed that DER 6 is a power-generating DER, particularly a naturally fluctuating power source whose power generation cannot be controlled. Therefore, the battery storage adjustment amount calculation unit 83 calculates the battery storage adjustment amount kWh(bat) based on the difference kWh(total)-kWh(DER) obtained by subtracting the DER adjustment amount kWh(DER) from the total adjustment amount kWh(total). That is, in this example, after determining the DER adjustment amount kWh(DER), the final power adjustment is performed using the battery storage adjustment amount kWh(bat). However, if DER 6 includes a storage-type DER, for example, the battery storage adjustment amount calculation unit 83 may allocate the total adjustment amount kWh(total) to the DER adjustment amount kWh(DER) and the battery storage adjustment amount kWh(bat), and use both the DER adjustment amount kWh(DER) and the battery storage adjustment amount kWh(bat) to perform power adjustment.

[0115] As described above, in this embodiment, the degree of deterioration of each used battery 9 is evaluated while it is stored in the storage unit 21. As a result, the storage period of the used batteries 9 can be effectively utilized in terms of time. Furthermore, the charging and discharging of the used batteries 9 for evaluating the degree of deterioration of the used batteries 9 is basically performed based on the DR request from the operator's server 50. In addition, when there are a large number of used batteries 9, when high power is charged and discharged, the high power is transferred between the battery storage warehouse 2 and the power system 5 based on the DR request from the operator's server 50. As a result, the operating company of the battery storage warehouse 2 can receive a reward (incentive) from the power company, and thus can use the reward as the operating cost of the battery storage warehouse 2. Alternatively, the operating company of the battery storage warehouse 2 can recover a portion of the initial investment (original cost) of the battery storage warehouse 2. As a result, the storage period of the used batteries 9 can also be effectively utilized in terms of money.

[0116] Furthermore, in this embodiment, the charging and discharging of used batteries 9 with relatively low levels of deterioration are suppressed compared to used batteries 9 with relatively high levels of deterioration. This prevents used batteries 9 with relatively low levels of deterioration from deteriorating during charging and discharging, thereby maintaining the quality of used batteries 9 with relatively low levels of deterioration. This ensures a sufficient inventory of high-quality used batteries 9.

[0117] In the aforementioned embodiment, the levels with relatively low levels of degradation that suppress charge and discharge are designated as S and A, while the levels with relatively high levels of degradation, different from the levels that suppress charge and discharge, are designated as B and C. However, this is not limiting, and the combination of the levels with relatively low and high levels of degradation that suppress charge and discharge may be other combinations. For example, the level with low levels of degradation may be designated as S, and the levels with high levels of degradation may be designated as A to C. Alternatively, the level with low levels of degradation may be designated as A, and the level with high levels of degradation may be designated as B. Alternatively, the level with low levels of degradation may be designated as S, A, and B, and the level with high levels of degradation may be designated as C.

[0118] While the embodiments of the present invention have been described, the embodiments disclosed herein are to be construed as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, and is intended to encompass all modifications within the meaning and scope of the claims and equivalents thereof.

Claims

1. A battery management system comprising: a storage vault for storing a plurality of batteries; a power conversion device electrically connected between the plurality of batteries stored in the storage and the power system, capable of performing bidirectional power conversion; a control device that controls the operation of the power conversion device in accordance with a demand response request from the power system, thereby charging and discharging the plurality of batteries; and a switching device configured to switch between electrical connection and electrical disconnection between the plurality of batteries and the power system; The control device suppresses discharge of the battery having the smaller degree of degradation compared to discharge of the battery having the larger degree of degradation among the degrees related to the degree of degradation of the battery. For each battery with a low degree of degradation, it is determined whether the SOC of the battery is within the SOC range where degradation progresses slowly. The SOC range is predetermined to be 40% to 60% based on the characteristics of the battery. When the SOC of a battery in a grade with a small degree of degradation is within an SOC range in which degradation progresses slowly, the control device controls the switching device so that the battery is electrically disconnected from the electric power system.

2. The battery management system according to claim 1, The control device also charges and discharges batteries of a less degraded level when the charge and discharge power of the plurality of batteries of a more degraded level is less than the charge and discharge power corresponding to the demand response request.

3. The battery management system according to claim 1, The control device makes the charge and discharge electric quantity of a battery of a level at which charge and discharge are suppressed smaller during a predetermined period than the charge and discharge electric quantity of a battery of a level different from the level at which charge and discharge are suppressed during the predetermined period.

4. The battery management system according to claim 1, The control device makes the charge and discharge frequency of the battery of the level where charge and discharge are suppressed lower than the charge and discharge frequency of the battery of the level different from the level where charge and discharge are suppressed.

5. A battery management method using a server, comprising: The server charges and discharges the plurality of batteries stored in the storage according to a demand response request from the power system; and a step of being able to switch electrical connection and disconnection between the plurality of batteries and the power system, The charging and discharging step includes the step of suppressing the discharge of the battery having a smaller degree of degradation than the discharge of the battery having a larger degree of degradation among the levels related to the degree of degradation of the battery, The switching step includes the following steps: for each battery with a low degree of degradation, determining whether the SOC of the battery is within an SOC range where degradation of the battery progresses slowly, the SOC range being predetermined to be 40% to 60% based on battery characteristics; and When the SOC of a battery in a battery class having a small degree of degradation is within an SOC range in which the degradation progresses slowly, the battery is electrically disconnected from the electric power system.

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