Battery management system and battery management method

Abstract

A battery management system and a battery management method are provided. A battery storage (2) is provided with: a battery group including a plurality of batteries; a power conversion device (AC / DC converter (22) and DC / DC converter (23)) electrically connected between the plurality of batteries and a power system (5); and a server (20) that controls the operation of the power conversion device in order to charge and discharge the plurality of batteries in accordance with a DR request from the power system (5). The battery group includes a low-operation group and a high-operation group, and the number of types of ranks included in the high-operation group is less than the number of types of ranks included in the low-operation group. The server (20) suppresses the charging and discharging of the plurality of batteries included in the low-operation group compared to the charging and discharging of the plurality of batteries included in the high-operation group. The inventory of the batteries of each rank can be ensured.

Description

Technical Field

[0001] This disclosure relates to battery management systems and battery management methods. Background Technology

[0002] Japanese Patent Application Publication No. 2018-205873 describes a call for users of electric vehicles equipped with batteries suitable for energy storage systems to replace those 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 amount of used batteries being recycled as these vehicles are replaced or dismantled is rising. From the perspective of advancing the Sustainable Development Goals (SDGs), there is a desire to reuse these recycled batteries by manufacturing new battery packs. The inventors focused on the potential problems that may arise when reusing used batteries, such as the following.

[0004] Batteries are stored at logistics hubs and other locations while awaiting use. Properly storing batteries incurs costs. Furthermore, there can be a considerable amount of time (storage period) between the receipt of recycled batteries and their dispatch for use. Therefore, it is desirable to make efficient use of the battery storage period.

[0005] Consider grading batteries based on their degree of degradation. The required rank varies depending on factors such as intended use. Therefore, there may be ranks with relatively high demand and ranks with relatively low demand. For a battery management system, the goal is to maintain an inventory of batteries in quantities corresponding to the demand for each rank. However, it's not possible to adjust the rank of batteries recalled from the market at the battery management system level. Furthermore, battery degradation can occur during storage in the battery management system, potentially lowering the rank. This could lead to a bias in the rank of batteries in inventory.

[0006] This disclosure was made to address the aforementioned problems, and its purpose is to ensure the availability of batteries of all grades.

[0007] (1) A battery management system according to one aspect of this disclosure comprises: a battery pack including a plurality of batteries; a power conversion device electrically connected between the plurality of batteries and a power system; and a control device that controls the operation of the power conversion device according to a demand response request from the power system, thereby causing the plurality of batteries included in the battery pack to charge and discharge. The battery pack includes a first battery pack and a second battery pack, wherein the number of types of grades included in the second battery pack in a grade related to the degree of battery degradation is less than the number of types of grades included in the first battery pack. The control device suppresses the charging and discharging of the plurality of batteries included in the first battery pack compared to the charging and discharging of the plurality of batteries included in the second battery pack.

[0008] In the configuration described in (1) above, the charging and discharging of the multiple batteries included in the first battery group is suppressed compared to the charging and discharging of the multiple batteries included in the second battery group, and the number of types of grades related to the degree of battery degradation in the second battery group is less than the number of types of grades included in the first battery group. Therefore, the grade of each grade of battery included in the first battery group is maintained compared to the grade of the batteries included in the second battery group. As a result, it is possible to ensure the inventory of batteries of each grade.

[0009] (2) The battery management system also includes a switching device configured to switch the electrical connection and disconnection between multiple batteries and the power system. The control device controls the switching device so that the batteries contained in the first battery group are electrically disconnected from the power system.

[0010] In the configuration described in (2) above, the batteries contained in the first battery pack are electrically disconnected from the power system. Therefore, the grade of the batteries contained in the first battery pack can be maintained more reliably.

[0011] (3) When the SOC of the batteries included in the first battery group is within a predetermined SOC range that can suppress the development of degradation, the control device suppresses the charging and discharging of the batteries included in the first battery group compared with the charging and discharging of the batteries included in the second battery group.

[0012] In the configuration described in (3) above, when the State of Charge (SOC) of the batteries included in the first battery group falls within a range that can suppress the development of degradation, the charging and discharging of the batteries included in the first battery group is suppressed. As a result, the grade of the batteries included in the first battery group can be maintained.

[0013] (4) The control device makes the charge and discharge capacity of the batteries in the first battery group during a predetermined period smaller than that of the batteries in the second battery group during a predetermined period.

[0014] (5) The control device makes the charging and discharging frequency of the batteries in the first battery group less than that of the batteries in the second battery group.

[0015] (6) Battery group 1 includes all battery grades. Therefore, the grades of all battery grades included in battery group 1 are maintained compared to the grades of batteries included in battery group 2. As a result, it is possible to ensure the availability of batteries of all grades.

[0016] (7) Other aspects of this disclosure relate to a battery management method that uses a server. This method includes the step of a server charging and discharging multiple batteries contained in a battery bank according to a demand response request from a power system. The battery bank includes a first battery bank and a second battery bank, wherein the second battery bank contains fewer types of grades related to the degree of battery degradation than the first battery bank contains. The charging and discharging step includes the step of suppressing the charging and discharging of the multiple batteries contained in the first battery bank compared to the charging and discharging of the multiple batteries contained in the second battery bank.

[0017] According to the method described in (6) above, the same configuration as described in (1) above can ensure the inventory of batteries of various grades.

[0018] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention, which is understood in conjunction with the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating one method of logistics for the battery pack in this embodiment.

[0020] Figure 2 This is a diagram illustrating an example of how used batteries are stored in a storage unit.

[0021] Figure 3 This is a flowchart outlining the operational procedures for reusing second-hand batteries.

[0022] Figure 4 This is a system configuration diagram showing the electrical structure of a battery storage compartment (cellar).

[0023] Figure 5 This is a diagram illustrating an example of a data structure representing battery data.

[0024] Figure 6 This is a conceptual diagram illustrating an example of a method for suppressing the charging and discharging of a used battery in this embodiment.

[0025] Figure 7This is a conceptual diagram illustrating another example of a method for suppressing the charging and discharging of a used battery in this embodiment.

[0026] Figure 8 This is a conceptual diagram illustrating yet another example of a method for suppressing the charging and discharging of a used battery in this embodiment.

[0027] Figure 9 This is a flowchart illustrating the first example of the processing sequence related to charge / discharge suppression in this embodiment.

[0028] Figure 10 This is a flowchart illustrating the second example of the processing sequence related to charge / discharge suppression in this embodiment.

[0029] Figure 11 This is a flowchart illustrating the third example of the processing sequence related to charge / discharge suppression in this embodiment.

[0030] Figure 12 This is a functional block diagram of a server related to the degradation evaluation of used batteries.

[0031] Figure 13 This is a functional block diagram of a server related to power regulation between the battery storage compartment and the power system. Detailed Implementation

[0032] In this disclosure and embodiments, battery charging and discharging means at least one of charging and discharging the battery. That is, battery charging and discharging is not limited to both charging and discharging; it can be either charging or discharging the battery alone.

[0033] In this disclosure, the battery pack includes multiple modules (also referred to as blocks or stacks). These modules can be connected in series or in parallel. Each module includes multiple battery cells (single cells).

[0034] Generally, battery pack "reuse" is broadly categorized into reuse, reassembly, and material recycling. In the reuse case, the recycled battery packs undergo necessary outgoing inspections and are shipped directly as reused products. In the reassembly case, the recycled battery packs are temporarily broken down into modules. Then, usable modules (or modules whose performance has been restored to usability) are combined to manufacture new battery packs. These newly manufactured battery packs undergo outgoing inspections and are shipped as reassembly products. In contrast, in material recycling, recyclable materials (resources) are extracted from each battery cell. The recycled battery packs are not used as other battery packs.

[0035] In the embodiments described below, the battery packs recovered from the vehicle are temporarily disassembled into modules. Various processes are then performed on a module-by-module basis. That is, in the following description, reusable second-hand batteries mean reassembleable modules. However, disassembly into modules is not mandatory. Depending on the battery pack's composition or degree of degradation, it may be reused without disassembly into modules.

[0036] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be given the same reference numerals, and their descriptions will not be repeated.

[0037] [Implementation Method]

[0038] <Battery Logistics Model>

[0039] Figure 1 This is a diagram illustrating one method of the logistics of the battery pack in this embodiment. In the following, Figure 1 The logistics method shown is called the "battery logistics model". The battery logistics model 100 includes a recycler 1, a battery storage warehouse 2, a buyer 3, a recycling plant 4, a power system 5, and distributed energy (DER: Distributed Energy Resource) 6.

[0040] Recycling operator 1 collects used battery packs (second-hand batteries 9) from multiple vehicles. Recycling operator 1 can be a vehicle dealership or a vehicle dismantling company. Furthermore, in this example, each second-hand battery 9 is assigned identification information (battery ID) (see reference). 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 (such as battery data described later), and track the circulation path of the used battery 9.

[0041] Battery storage compartment 2 is a facility used to properly manage used batteries 9 collected by recycling company 1, similar to a wine cellar where wine bottles are stored under controlled temperature and humidity. Battery storage compartment 2... Figure 1 The example shown is a logistics hub located near a harbor. Battery storage warehouse 2 includes a server 20 for managing data related to used batteries 9 and multiple storage units 21. Furthermore, battery storage warehouse 2 is equivalent to the "battery management system" disclosed herein. Storage units 21 are equivalent to the "warehouse" disclosed herein. Batteries stored in battery storage warehouse 2 are not limited to used batteries, but may also include new batteries.

[0042] Figure 2 This diagram illustrates an example of how the used battery 9 is stored in storage unit 21. (See diagram for example.) Figure 2As shown, multiple storage units 21 are arranged within the battery storage compartment 2 building. Each storage unit 21 is configured to store a large number of used batteries 9. Details will be described later, but in this embodiment, the battery storage compartment 2 performs degradation evaluation tests on each of the used batteries 9 stored in the storage unit 21. Furthermore, based on the results of the degradation evaluation tests, the battery storage compartment 2 determines whether each used battery 9 can be reused (whether it is suitable for reuse).

[0043] return Figure 1 Buyer 3 sells used batteries 9 that are determined by battery storage compartment 2 to be reusable. Buyer 3 may include a sales store 31 that sells used batteries 9 as vehicle batteries and users 32 that use them as stationary batteries in factories, buildings, etc. Additionally, buyer 3 may also include a sales store 33 that sells used batteries 9 as supplies (replacement parts for maintenance and repair).

[0044] The recycling plant 4 is used to recycle second-hand batteries 9 that have been determined by the battery storage bin 2 to be unusable as raw materials for other products.

[0045] Power system 5 is a power grid constructed from power plants and transmission and distribution equipment. In this embodiment, the power company acts as both a power generator and a power transmission and distribution operator. The power company is equivalent to a general power transmission and distribution operator, and also to the manager of power system 5, maintaining and managing power system 5. A service provider server 50 is installed in power system 5. Service provider server 50 belongs to the power company and manages the power supply and demand of power system 5. Server 20 and service provider server 50 are configured to enable bidirectional communication.

[0046] DER6 is a relatively small-scale electrical device installed at a logistics base (or its surrounding area) where a battery storage compartment 2 is located, capable of receiving and exchanging power with the battery storage compartment 2. DER6 includes, for example, generator-type DERs and battery storage-type DERs.

[0047] A power generation-type DER can include naturally volatile power sources and generators. Naturally volatile power sources are power generation devices whose output varies according to weather conditions. Figure 1 The illustration shows a solar power generation device (solar panel), but natural variable power sources can also replace solar power generation devices or include wind power generation devices in addition to solar power generation devices. On the other hand, a generator is a power generation device that is independent of weather conditions. Generators can include steam turbine generators, gas turbine generators, diesel engine generators, gas engine generators, biomass generators, stationary fuel cells, etc. Generators can also include combined heat and power (CHP) systems that utilize the heat generated during power generation.

[0048] Energy storage-type DERs can include electrical storage systems and thermal storage systems. An electrical storage system is a stationary energy storage device that stores electricity generated by natural and fluctuating power sources. An electrical storage system can also be a power-to-gas (PTO) device that uses electricity to produce gaseous fuels (hydrogen, methane, etc.). A thermal storage system includes a heat storage tank located between a heat source and a load, configured to temporarily store a liquid medium within the tank in an insulated state. By using a thermal storage system, the generation and consumption of heat can be staggered over time. Therefore, for example, electricity can be consumed at night, and the heat generated by operating the heat source can be stored in the heat storage tank, which can then be consumed during the day for air conditioning.

[0049] Thus, the used batteries 9 collected by the recycling company 1 are stored in the battery storage warehouse 2 while awaiting shipment to the buyer 3 or the recycling plant 4. However, using the battery storage warehouse 2 to properly store the used batteries 9 also incurs maintenance costs (operating costs). Furthermore, there may be a certain amount of time between the receipt of the collected used batteries 9 and their shipment to the buyer 3 or the recycling plant 4. Therefore, it is desirable to make efficient use of the storage period of the used batteries 9 in the battery storage warehouse 2.

[0050] In this embodiment, the battery storage silo 2 also functions as a virtual power plant (VPP) in addition to the storage location of the used batteries 9. Thus, the opportunity for the used batteries 9 to charge and discharge simultaneously serves as a degradation assessment for determining the reuse method of the used batteries 9, and an adjustment of the power supply and demand balance of the power system 5 utilizing the used batteries 9. As a result, the storage of used batteries 9, degradation assessment of used batteries 9, and adjustment of the power supply and demand balance based on used batteries 9 are all performed in a "three-in-one" manner within the battery storage silo 2.

[0051] <Reuse Process of Second-hand Batteries>

[0052] Figure 3 This is a flowchart outlining the operational procedures for reusing the second-hand battery 9. First, the second-hand battery 9, collected by the recycling operator 1, is handed over to the battery storage bin 2 (S1).

[0053] In this embodiment, the server 20 performs a degradation evaluation test (performance check) (S2) on each of the used batteries 9 while they are stored in the storage unit 21. 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). Furthermore, based on the results of the degradation evaluation test, the server 20 determines whether each used battery 9 can be reused (S3).

[0054] In this embodiment, the used battery 9 is rated based on the results of the degradation evaluation test (more specifically, the measurement results of full charge capacity). For example, as Figure 2 As shown, the reusable used batteries 9 are graded into four levels—S, A, B, and C—in descending order of their full-charge capacity. This allows for the setting of transaction prices for the used batteries 9 in relation to their grade, and ensures the quality of the used batteries 9 based on their grade. This enables the used batteries 9 that have passed through the battery storage bin 2 to circulate smoothly in the market. Furthermore, used batteries 9 with a full-charge capacity below a specified value are graded lower than C (recorded as Re) and transferred to material recycling.

[0055] If it is determined that the battery can be reused ("Yes" in S3), the operation proceeds to the performance recovery step (S4). In the performance recovery step, a process to restore the performance of the used battery 9 is performed (performance recovery treatment). For example, by overcharging the used battery 9, its full charge capacity can be restored. However, the performance recovery step can be omitted. Alternatively, performance recovery treatment can be performed on used batteries 9 that show a high degree of degradation (significant performance reduction) according to the degradation evaluation test, while performance recovery treatment is not performed on used batteries 9 with a low degree of degradation (minimal performance reduction).

[0056] Next, using the used battery 9 whose performance has been restored through the performance restoration process, a new battery pack is manufactured (reassembled) (S5). The used battery 9 used in the battery pack reassembly is basically a used battery 9 whose performance has been restored through the performance restoration process, but it can include used batteries 9 that have omitted the performance restoration process, or it can include new batteries (new modules). Then, the battery pack is sold and shipped to buyer 3 (S6).

[0057] If the degradation evaluation test results in a determination that the battery is no longer reusable ("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 dismantled and recycled.

[0058] Thus, from the time the used battery 9 is collected by the recycling operator 1 until it is handed over to the buyer 3 or the recycling plant 4, it is stored in the battery storage compartment 2, during which a degradation evaluation test is conducted. During the degradation evaluation test, the used battery 9 is charged and discharged to measure its full-charge capacity and other electrical characteristics. In this embodiment, the charging and discharging is performed using power transferred between the battery storage compartment 2 (and DER6) and the power system 5. Therefore, the battery storage compartment 2 functions as a VPP (or one of the DERs), contributing to the load balancing of the power system 5. More specifically, during periods when there is a surplus in the power system 5's supply to meet demand, the battery storage compartment 2 absorbs the surplus power by charging the used battery 9. On the other hand, when there is a shortage in the power system 5's supply to meet demand, the battery storage compartment 2 alleviates the power shortage by releasing the insufficient power from the used battery 9.

[0059] However, the battery storage compartment 2 may not be configured to contribute to both absorbing excess power and mitigating insufficient power in the power system 5. The battery storage compartment 2 may also be configured to contribute only to absorbing excess power and mitigating insufficient power. For example, the battery storage compartment 2 may be configured to charge the remaining power in the power system 5 to the used battery 9, while ensuring that the discharge destination from the used battery 9 does not include the power system 5. The discharge destination from the used battery 9 may, for example, be only DER6.

[0060] <System Composition of Battery Storage Compartment>

[0061] Figure 4 This 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. Furthermore, in... Figure 4 For the sake of convenience on paper, only one storage unit 21 is shown in the diagram, but as... Figure 2 As shown, a typical battery storage compartment 2 has multiple storage units 21.

[0062] Storage unit 21 stores multiple used batteries 9. Figure 4 In this example, multiple used batteries 9 are connected in parallel, but this is merely an example, and the connection method of the 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. The storage unit 21 includes a voltage sensor 211, a current sensor 212, and a relay 213.

[0063] Voltage sensor 211 detects the voltage VB of the used battery 9 and outputs its detection value to server 20. Current sensor 212 detects the charging and discharging current IB in the used battery 9 and outputs its detection value to server 20. Furthermore, if temperature is used in the degradation evaluation of the used battery 9, storage unit 21 may also include a temperature sensor (not shown). Alternatively, each sensor may be a sensor already present in the used battery 9.

[0064] Relay 213 includes, for example, a first relay electrically connected to the positive terminal of the used battery 9 and a second relay electrically connected to the negative terminal of the used battery 9. Relay 213 is configured to switch the electrical connection and disconnection between the used battery 9 and the power system 5. Thus, any used battery 9 can be electrically disconnected during the charging and discharging of other used batteries 9, and removed from the storage unit 21. Furthermore, relay 213 corresponds to the "switching device" disclosed herein.

[0065] AC / DC converter 22 is electrically connected between power system 5 and DC / DC converter 23. AC / DC converter 22 is configured to perform bidirectional power conversion operations for charging and discharging the used battery 9 stored in the storage unit, according to control commands (charge / discharge commands) from server 20. More specifically, AC / DC converter 22 converts the AC power supplied from power system 5 into DC power for charging the used battery 9. Additionally, AC / DC converter 22 converts the DC power discharged from the used battery 9 into AC power for supplying to power system 5.

[0066] DC / DC converter 23 is electrically connected between AC / DC converter 22 and storage unit 21, and also electrically connected between DER6 and storage unit 21. DC / DC converter 23, like AC / DC converter 22, is configured to perform bidirectional power conversion operations according to control commands (charge / discharge commands) from server 20. DC / DC converter 23 can charge the used battery 9 with DC power from AC / DC converter 22 and / or DER6, and discharge the DC power stored in the used battery 9 to AC / DC converter 22 and / or DER6.

[0067] 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. Server 20 performs various controls based on signals received from various sensors, programs stored in memory, and maps. 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.

[0068] The battery data storage unit 201 stores battery data used for managing used batteries 9 in the battery storage compartment 2.

[0069] Figure 5 This is a diagram illustrating an example of a data structure for battery data. Battery data is stored, for example, in a mapped format. Battery data includes, for example, identification information (battery ID) for identifying the used battery 9, the model number of the used battery 9, manufacturing date, current SOC (State of Charge), full charge capacity, rating, degradation evaluation date (the latest date the degradation evaluation test was conducted), and storage location (the identification information of the storage unit where the used battery 9 is stored) as parameters. Furthermore, battery data may also include parameters other than those mentioned above (such as the internal resistance of the used battery 9, an index ΣD indicating the bias of the salt concentration distribution in the electrolyte of the used battery 9, etc.).

[0070] 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 current IB detected by the voltage sensor 211 and current sensor 212 respectively during the charging and discharging of the used battery 9. Figure 12 An example illustrating this evaluation method is provided. The degradation evaluation department 202 rates the used battery 9 based on the results of the degradation evaluation test.

[0071] The power adjustment unit 203 performs power adjustments between the battery storage compartment 2 (and DER6) and the power system 5. More specifically, server 20 selects from multiple used batteries 9 to respond to power from the operator's server 50 (see reference). Figure 1 The selected used battery 9 is charged and discharged in response to a demand response (DR) request. The power regulation unit 203 outputs commands to the relay 213, AC / DC converter 22, and DC / DC converter 23 to charge and discharge the selected used battery 9. Figure 13An example of this control method will be provided.

[0072] The timing adjustment unit 204 adjusts the timing of the degradation evaluation test of the used battery 9 conducted by the degradation evaluation unit 202 and the timing of the power adjustment between the battery storage compartment 2 and the power system 5 conducted by the power adjustment unit 203. More specifically, the timing adjustment unit 204 performs timing adjustments so that the degradation evaluation test of the used battery 9 is performed in accordance with the timing of the DR (Degradation Response) of the battery storage compartment 2 in response to the DR request from the operator server 50. Furthermore, the degradation evaluation test performed in accordance with the DR of the battery storage compartment 2 is not limited to the used battery 9; performance recovery processing can also be performed based on the degradation evaluation test (see reference). Figure 3 S4).

[0073] Display unit 205 displays battery data (see reference) based on the operation of the manager of battery storage compartment 2 (or the operator working in battery storage compartment 2). Figure 5 Furthermore, the display unit 205 displays the progress and results of the degradation evaluation test conducted by the degradation evaluation unit 202. This allows the manager to monitor the status of the degradation evaluation test. Additionally, 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 manager to monitor the power adjustment status between the battery storage compartment 2 and the power system 5.

[0074] Furthermore, server 20 is equivalent to the "control device" involved in this disclosure. AC / DC converter 22 and DC / DC converter 23 are equivalent to the "power conversion device" involved in this disclosure.

[0075] <Inventory Assurance>

[0076] Depending on the intended use for reuse, the required grade varies. Therefore, there may be grades with relatively high demand, and grades with relatively low demand. It is desirable to maintain a sufficient quantity of used batteries 9 in the battery storage bin 2, categorized by grade, to meet the reuse demand. However, it is not possible to adjust the grade of used batteries 9 collected from the market at the battery storage bin 2. Furthermore, the used batteries 9 may deteriorate during storage in the battery storage bin 2, thus lowering their grade. In particular, in the battery storage bin 2, each used battery 9 is repeatedly charged and discharged for power adjustments with the power system 5, making deterioration of the used batteries 9 easy to occur. This could lead to a bias in the grade of the used batteries 9 in the inventory.

[0077] Therefore, in this embodiment, the battery group including multiple used batteries 9 comprises a low-operation group and a high-operation group. The number of different grades (any one of grades S, A to C in this embodiment) included in the high-operation group is less than that in the low-operation group. Compared with the charging and discharging of the used batteries 9 in the high-operation group, the server 20 suppresses the charging and discharging of the used batteries 9 in the low-operation group. As a result, the grade of each grade of used batteries included in the low-operation group is maintained compared with the grade of the used batteries included in the high-operation group. Consequently, the inventory of used batteries of each grade can be ensured.

[0078] Furthermore, compared to the high-operation group, it is desirable for the low-operation group to include all grades of used batteries equally. However, it does not have to be completely equal. For example, it can be set to include used batteries of each grade at a ratio similar to that of each grade in the entire battery group, or it can be set to include all grades of used batteries so that the number of used batteries of each grade is greater than or equal to the minimum number required for inventory. The low-operation group is set to include all grades of used batteries, but the high-operation group may or may not include all grades of used batteries. In addition, it is desirable for the low-operation group to include all grades of types, but it is also acceptable not to include all grades of types if the number of types of types of grades included in the high-operation group is greater than or equal to the number of types of grades included in the high-operation group.

[0079] Figure 6 This is a conceptual diagram illustrating an example of a method for suppressing the charging and discharging of the second-hand battery 9 in this embodiment. Figure 7 This is a conceptual diagram illustrating another example of a method for suppressing the charging and discharging of the second-hand battery 9 in this embodiment. Figure 8 This is a conceptual diagram illustrating yet another example of the method for suppressing the charging and discharging of the used battery 9 in this embodiment. Figures 6-8 In the diagram, the horizontal axis represents the elapsed time. The vertical axis represents the amount of electricity generated by charging and discharging from the battery storage compartment 2 (second-hand battery 9) relative to the power system 5.

[0080] like Figure 6 As shown, the charge / discharge amount (charge and discharge capacity) of the used battery 9 in the low-operation group during a predetermined period can be made smaller than that of the used battery 9 in the high-operation group during a predetermined period (first control). Here, the method for reducing the charge / discharge amount during the predetermined period is not limited to adjusting the magnitude (e.g., peak value) of the charge / discharge power (see reference). Figure 6 ), or as Figure 7 The length of the charging / discharging period can be adjusted as shown. It is also possible to adjust both the amount of charging / discharging power and the length of the charging / discharging period. Additionally, as shown... Figure 8As shown, the charging and discharging frequency of the used battery 9 in the low-operation group can also be less than that of the used battery 9 in the high-operation group (second control). Although not shown, regarding the used battery 9 in the low-operation group, both the charging and discharging amount and the charging and discharging frequency can be suppressed compared to the used battery 9 in the high-operation group. That is, the first control and the second control can also be used together.

[0081] <Charge and Discharge Suppression Process>

[0082] Figure 9 This is a flowchart illustrating the first example of the processing sequence related to charge / discharge suppression in this embodiment. This flowchart (and other flowcharts described later) is invoked and executed by the main routine (not shown) when predetermined conditions are met. Each step is implemented by software processing based on server 20, but may also be implemented by hardware (circuit) configured within server 20. Hereinafter, steps will be abbreviated as S.

[0083] In S12, server 20 calculates the amount of power adjustment required from battery storage compartment 2 between battery storage compartment 2 and power system 5. This amount will be referred to as battery storage compartment adjustment, and also denoted as kWh (bat). Figure 10 A detailed explanation is given of an example of how to calculate the adjustment amount (kWh / bat) of the battery storage compartment.

[0084] In S13, 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 amount ΔkWh(bat). If the battery storage compartment adjustment amount ΔkWh(bat) is greater than the amount of electricity that can be charged and discharged using all the used batteries 9, server 20 determines that there is no margin. If there is no margin ("No" in S13), in order to make the amount of electricity charged and discharged in battery storage compartment 2 close to the battery storage compartment adjustment amount ΔkWh(bat), it is required that all the used batteries 9 be charged and discharged. Therefore, server 20 charges and discharges all the used batteries 9 (S19).

[0085] On the other hand, when there is a margin, i.e., the battery storage adjustment amount kWh(bat) is less than the amount of charge and discharge that can be achieved using all the used batteries 9 ("Yes" in S13), the battery storage adjustment amount ΔkWh(bat) can be met even without charging and discharging all the used batteries 9. In this case, the server 20 determines that the charge and discharge amount of the used batteries 9 in the low-operation group is less than that of the used batteries 9 in the high-operation group (S14).

[0086] Figure 10 This is a flowchart illustrating the second example of the processing sequence related to charge / discharge suppression in this embodiment. The processing steps S22, S23, and S29 are... Figure 9 The processes S12, S13, and S19 shown are the same, therefore, they will not be explained again. Figure 10 As shown, server 20 can also determine the charging and discharging frequency of the used battery 9 in the low-operation group to be less than that of the used battery 9 in the high-operation group (S24).

[0087] In this way, by reducing the amount of charging and discharging used for power regulation and the frequency of charging and discharging compared to the used batteries 9 in the high-operation group, the degradation associated with charging and discharging can be suppressed. Therefore, the grade of each grade of used batteries 9 in the low-operation group is maintained compared to the grade of the used batteries 9 included in the high-operation group. As a result, sufficient inventory of used batteries 9 at each grade can be ensured.

[0088] Figure 11 This is a flowchart illustrating the third example of the processing sequence related to charge / discharge suppression in this embodiment. The processing steps S32, S33, and S39 are... Figure 9 The processes S12, S13, and S19 shown are the same, so they will not be described again. If the total amount of electricity that can be used to charge and discharge all the used batteries 9 has a margin of safety for the battery storage compartment adjustment amount kWh (bat) ("Yes" in S33), the server 20 causes the process to proceed to S34.

[0089] In step S34, for each used battery 9 in the low-operation group, it is determined whether the SOC of the used battery 9 is within a predetermined SOC range. This SOC range is the range where the degradation of the used battery 9 develops slowly, and is predetermined based on the characteristics of the used battery 9. Generally speaking, when the SOC of a secondary battery is too high (e.g., exceeding 80%) or too low (e.g., less than 20%), the degradation of the secondary battery is likely to develop. Therefore, it is desirable that the aforementioned SOC range is an intermediate SOC range (e.g., an SOC range of 40% to 60%).

[0090] If the SOC of a certain used battery 9 in the low-operation group is within the range of a slowly deteriorating SOC ("Yes" in S34), the server 20 disconnects the relay 213 corresponding to the used battery 9 so that the used battery 9 is disconnected from the power system 5 (S35).

[0091] Furthermore, if too many used batteries 9 are disconnected from the power system 5, the amount of electricity charged and discharged from the battery storage compartment 2 may be insufficient relative to the battery storage compartment adjustment amount (kWh(bat)). Therefore, it is desirable for the server 20 to consider the battery storage compartment adjustment amount (kWh(bat)) when controlling the relay 213. That is, it is desirable for the server 20 to adjust the number of used batteries 9 disconnected from the power system 5 so that the number of used batteries 9 required to meet the battery storage compartment adjustment amount (kWh(bat)) remains electrically connected to the power system 5.

[0092] In S36, server 20 performs power adjustment with power system 5 by charging and discharging the remaining used battery 9 (with relay 213 closed) and the used battery 9 in the high-operation group. The remaining used battery 9 with relay 213 closed is the remaining used battery 9 in the low-operation group that remains electrically connected to power system 5. That is, the remaining used battery 9 with relay 213 closed is a used battery 9 outside the range of SOC (State of Charge) that is slowly deteriorating. Furthermore, the higher the temperature, the more easily the used battery 9 deteriorates. Therefore, server 20 can also impose certain limits on the charging and discharging current so that the used battery 9 does not become excessively hot due to the heat generated during charging and discharging.

[0093] In this way, the used battery 9, which is disconnected from the power system 5 by disconnecting relay 213, is no longer used in charging and discharging for power regulation, thus suppressing degradation associated with charging and discharging. Furthermore, the state of charge (SOC) of the used battery 9, which is disconnected from the power system 5, is maintained within a range where degradation develops slowly. Therefore, degradation during storage that is not caused by charging and discharging (so-called long-term degradation or material degradation) can also be suppressed.

[0094] Furthermore, S34 processing can also be applied to Figure 9 and / or Figure 10 The flowchart is shown. Server 20 can reduce the charging and discharging amount and frequency of used battery 9 in low-operation groups when the SOC of used battery 9 is in a range where the deterioration is slow.

[0095] In addition, regarding Figures 9-11 In any example, server 20 can also suppress the charging and discharging of a used battery 9 of the same grade that has been designated as a buyer, compared to the charging and discharging of a used battery 9 of the same grade that has not yet been designated as a buyer. That is, server 20 can also suppress the charging and discharging of a used battery 9 designated as a buyer, even if it is a used battery 9 in a high-performance group. As a result, it is possible to suppress the deterioration of the used battery 9 during the storage period until its sale, and thus, it is possible to prevent the grade from decreasing from the point in time when the buyer is designated.

[0096] <Degradation Assessment>

[0097] Figure 12 This is a functional block diagram of the server 20 (degradation evaluation unit 202) related to the degradation evaluation of the used battery 9. For simplicity, the following explanation focuses on a single used battery 9. However, in practice, when multiple used batteries 9 have not undergone degradation evaluation, the same processing can be performed on all of them simultaneously. The degradation evaluation unit 202 includes a current accumulation unit 71, an OCV (Open Circuit Voltage) calculation unit 72, a SOC change calculation unit 73, a full charge capacity calculation unit 74, and a rating unit 75.

[0098] The current accumulation unit 71 calculates the cumulative value (cumulative current amount) ΔAh (unit: Ah) of the current that was charged and discharged in the used battery 9 during the period from the time the start condition for current accumulation was met to the time the end condition for current accumulation was met, based on the current IB detected by the current sensor 212. In this embodiment, as described above, the charging and discharging of the used battery 9 is performed according to the DR request from the operator server 50, and the current flowing during the DR is accumulated. More specifically, when performing an increased DR (increased power demand request), 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 accumulated. On the other hand, when performing a decreased DR, the used battery 9 is discharged to reduce the power demand of the battery storage compartment 2, and the discharging current at that time is accumulated. The current accumulation unit 71 outputs the calculated cumulative current amount ΔAh to the full charge capacity calculation unit 74.

[0099] The OCV calculation unit 72 calculates the OCV of the used battery 9 at the start of current accumulation and the OCV of the used battery 9 at the end of current accumulation. The OCV can be calculated, for example, according to the following formula (1).

[0100] OCV=VB-ΔVp-IB×R···(1)

[0101] In equation (1), the internal resistance of the used battery 9 is denoted as R, and the polarization voltage is denoted as Vp. At the start of current accumulation (just before charging and discharging begins), the current IB = 0. Furthermore, if the used battery 9 is left uncharged or undischarged before the start of current accumulation, the polarization voltage Vp ≒ 0 can be approximated. Therefore, the OCV at the start of current accumulation 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 voltage VB and current IB (Ohm's law). Additionally, if the used battery 9 is charged and discharged at a constant current, the polarization voltage Vp can be determined based on the current IB detected by the current sensor 212 by pre-measuring the relationship between current and polarization voltage Vp. Therefore, the OCV of the used battery 9 at the end of current accumulation can also be calculated based on voltage VB and current IB. The OCV calculation unit 72 outputs the calculated two OCVs to the SOC change calculation unit 73.

[0102] The SOC change calculation unit 73 calculates the SOC change ΔSOC of the used battery 9 from the start of current accumulation to the end of current accumulation based on two OCV values. The SOC change calculation unit 73 has a characteristic curve (OCV-SOC curve) representing the SOC dependence 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 accumulation and the SOC corresponding to the OCV at the end of current accumulation, 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.

[0103] The full charge capacity calculation unit 74 calculates the full charge capacity C of the used battery 9 based on ΔAh from the current accumulation 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 formula (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 initial full charge capacity C0 is known according to the specifications of the used battery 9, the full charge capacity calculation unit 74 can further calculate the capacity retention 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.

[0104] C=ΔAh / ΔSOC×100···(2)

[0105] The rating department 75 rates the used battery 9 based on its full charge capacity C. The rating department 75 records the rating date as the degradation assessment date in the battery data (see reference). Figure 5 ).

[0106] The grade of the used battery 9, along with its battery ID, storage location, etc., is displayed on the display unit 205. Therefore, upon receiving a purchase request for a used battery 9 from the buyer 3, the operator working in the battery storage compartment 2 can retrieve a used battery 9 of the grade required by the buyer 3 from its storage location. By appropriately retrieving the used batteries for sale from the storage unit 21, it is possible to prevent the storage unit 21 from becoming empty.

[0107] Furthermore, the method for calculating the full charge capacity C described above is merely one example. To calculate the full charge capacity C, any method can be used, as long as it employs the voltage VB and current IB measured during the charging and discharging of the used battery 9. Alternatively, the rating unit 75 can determine the grade of the used battery 9 based on other characteristics (internal resistance R of the used battery 9, index ΣD indicating the bias of electrolyte concentration in the lithium-ion battery, etc.) instead of the full charge capacity C. Additionally, the rating unit 75 can determine the grade 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. While the accuracy may be slightly reduced, the rating unit 75 can also determine the grade of the used battery 9 based on the elapsed time since its manufacture. The rating unit 75 can also combine the aforementioned factors (full charge capacity C, internal resistance R, index ΣD, charging and discharging time, number of charging and discharging cycles, elapsed time since manufacturing, etc.) to determine the grade of the used battery 9.

[0108] <Power Adjustment>

[0109] Figure 13 This is a functional block diagram of the server 20 (power adjustment unit 203) related to power adjustment between the battery storage compartment 2 and the power system 5. In this example, to facilitate understanding, we will assume that the DER6 is a power generation type DER (especially a naturally fluctuating power source such as a solar power generation device). The power adjustment unit 203 includes an overall adjustment amount calculation unit 81, a DER adjustment amount calculation unit 82, a battery storage compartment adjustment amount calculation unit 83, a used battery selection unit 84, a conversion calculation unit 85, and an instruction generation unit 86.

[0110] The overall adjustment calculation unit 81 receives a DR request from the business server 50 and calculates the total amount of electricity required for power adjustment using battery storage compartment 2 and DER6 during a predetermined period (e.g., 30 minutes). This amount of electricity will be referred to as the overall adjustment amount, also denoted as kWh (total). The overall adjustment calculation unit 81 outputs the calculated kWh (total) to the battery storage compartment adjustment calculation unit 83.

[0111] The DER adjustment calculation unit 82 obtains the operating status of each DER6 (more specifically, the expected amount of electricity generated by each DER6 during a predetermined period) through communication with each DER6. Hereinafter, this amount of electricity is referred to as the DER adjustment amount, also recorded as kWh(DER). The DER adjustment calculation unit 82 outputs the obtained kWh(DER) to the battery storage compartment adjustment calculation unit 83.

[0112] The battery storage compartment adjustment amount calculation unit 83 calculates the amount of electricity required for power adjustment using 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. Hereinafter, this amount of electricity is referred to as the battery storage compartment adjustment amount, also recorded as kWh(bat). For example, the battery storage compartment adjustment amount calculation unit 83 can calculate ΔkWh = kWh(total) - kWh(DER), which is the difference between the two amounts, 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.

[0113] The used battery selection department 84, regarding the large number of used batteries 9 stored in multiple storage units 21, determines the charge / discharge capacity of each used battery (refer to...). Figure 5 (Battery data). The used battery selection unit 84 selects used batteries for power adjustment from a large number of used batteries 9 based on the kWh (bat) calculated by the battery storage compartment adjustment unit 83. When kWh (bat) > 0, the power deficiency of the power system 5 is filled by discharging from the battery storage compartment 2. Therefore, the used battery selection unit 84 selects a number of used batteries 9 that can be discharged with a capacity of kWh (bat) or more. On the other hand, when kWh (bat) < 0, the remaining power of the power system 5 is absorbed by charging the battery storage compartment 2. Therefore, the used battery selection unit 84 selects a number of used batteries 9 that can be charged with a capacity of kWh (bat) (absolute value) or more. When selecting used batteries 9, used batteries 9 with high operating rates are given priority for charging and discharging, while used batteries 9 with low operating rates are avoided as much as possible. Regarding this process, using Figures 9-11 The details have been explained in detail, so they will not be repeated here. The used battery selection unit 84 outputs the selected used battery 9 and the amount of power allocated to each selected used battery 9 (the amount of power adjusted by each used battery 9) to the conversion calculation unit 85.

[0114] The conversion calculation unit 85 calculates the power required for charging and discharging each used battery 9 selected by the used battery selection unit 84. More specifically, the conversion calculation unit 85 converts the amount of power (in kWh) adjusted by each used battery 9 into power (in kW) using the remaining time for power adjustment. As an example, if a used battery 9 is allocated 10 kWh of power adjustment and has 15 minutes of remaining time for power adjustment, the result is 10 kWh × (60 minutes / 15 minutes) = 40 kW. The conversion calculation unit 85 outputs the power required for charging and discharging each used battery 9 to the instruction generation unit 86.

[0115] Based on the calculation results of the transformation calculation unit 85, the instruction generation unit 86 generates charge / discharge instructions for the AC / DC converter 22 and the DC / DC converter 23, and generates on / off instructions for the relay 213. More specifically, the instruction generation unit 86 generates on / off instructions such that the selected used battery 9 is electrically connected to the DC / DC converter 23, while the unselected used battery 9 is electrically disconnected from the DC / DC converter 23. The instruction generation unit 86 generates charge / discharge instructions to perform a total charge / discharge operation on the selected used battery 9, distributing the total power allocated to it.

[0116] In addition, confirmatory recording Figure 13 The power adjustment method shown is merely an example. In this example, it is assumed that DER6 is a power-generating DER, specifically a naturally fluctuating power source whose power generation cannot be controlled. Therefore, the battery storage adjustment 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, for example, if DER6 includes a storage-type DER, the battery storage adjustment calculation unit 83 may also allocate the total adjustment amount kWh(total) to both the DER adjustment amount kWh(DER) and the battery storage adjustment amount kWh(bat), and perform power adjustment using both the DER adjustment amount kWh(DER) and the battery storage adjustment amount kWh(bat).

[0117] 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. This allows for efficient utilization of the storage period of the used batteries 9. Furthermore, the charging and discharging of the used batteries 9 used for evaluating their deterioration is primarily based on DR requests from the operator server 50. Additionally, when there are many used batteries 9, during high-power charging and discharging, the high power is transmitted between the battery storage compartment 2 and the power system 5 based on DR requests from the operator server 50. This allows the operating company of the battery storage compartment 2 to receive payment of rewards from the power company, which can then be used as operating costs for the battery storage compartment 2. Alternatively, the operating company of the battery storage compartment 2 can recover a portion of the initial investment (original cost) of the battery storage compartment 2. This also allows for efficient utilization of the money from the storage period of the used batteries 9.

[0118] Furthermore, in this embodiment, the charging and discharging of the used batteries 9 in the low-operation group is suppressed compared to that in the high-operation group. This suppresses the degradation of the used batteries 9 in the low-operation group due to charging and discharging, thus maintaining the quality of each grade of used batteries 9 within the low-operation group. Consequently, sufficient inventory of used batteries 9 at each grade can be ensured.

[0119] In the aforementioned embodiments, the used battery 9 that functions as a VPP can be stored in the battery storage compartment 2 or not. Furthermore, the battery storage compartment 2 can be divided into an area for storing high-performance used batteries 9 and an area for storing low-performance used batteries 9, or it can be undivided.

[0120] In the aforementioned embodiment, the used batteries 9 stored in the battery storage compartment 2 are divided into a low-operation group and a high-operation group. However, this is not a limitation; the used batteries 9 stored in the battery storage compartment 2 may also be divided into three or more groups, including a first battery group and a second battery group, and the same processing as described above for the low-operation group and the high-operation group may be performed on the first battery group and the second battery group within each group. In this case, the first battery group corresponding to the low-operation group is configured to include used batteries 9 of all grades.

[0121] Embodiments of the present invention have been described, but should be considered as illustrative in all respects and not restrictive. The scope of the invention is defined by the claims and is intended to include all modifications within the meaning and scope of the claims.

Claims

1. A battery management system, comprising: A battery pack, which consists of multiple batteries; A power conversion device, which is electrically connected between the plurality of batteries and the power system; A control device that controls the operation of the power conversion device according to demand response requests from the power system, thereby charging and discharging the plurality of batteries contained in the battery bank; and A switching device configured to switch the electrical connection and disconnection between the plurality of batteries and the power system. The battery pack includes a first battery pack and a second battery pack. The second battery pack contains fewer types of grades related to the degree of battery degradation than the first battery pack contains. Compared to the charging and discharging of the plurality of batteries included in the second battery group, the control device suppresses the charging and discharging of the plurality of batteries included in the first battery group. For each battery in the first battery group with a low degree of degradation, it is determined whether the state of charge (SOC) of that battery is within the SOC range where battery degradation progresses slowly. This SOC range is predetermined to be 40% to 60% based on the characteristics of the battery. When the SOC of a battery in the first battery group, which is of a low degree of degradation, is within a range where degradation is slow to develop, the control device controls the switching device to disconnect the battery from the power system.

2. The battery management system according to claim 1, When the SOC of the batteries in the first battery group is within a predetermined SOC range that can suppress the development of degradation, the control device suppresses the charging and discharging of the batteries in the first battery group compared to the charging and discharging of the batteries in the second battery group.

3. The battery management system according to claim 1, The control device causes the charge / discharge capacity of the batteries in the first battery group during a predetermined period to be less than that of the batteries in the second battery group during the predetermined period.

4. The battery management system according to claim 1, The control device causes the charging and discharging frequency of the batteries in the first battery group to be less than that of the batteries in the second battery group.

5. The battery management system according to claim 1, The first battery group includes batteries of all grades.

6. A battery management method that utilizes server battery management techniques. This includes the steps of the server charging and discharging multiple batteries within the battery bank based on demand response requests from the power system. The battery pack includes a first battery pack and a second battery pack. The second battery pack contains fewer types of grades related to the degree of battery degradation than the first battery pack contains. The charging and discharging steps include the following steps: suppressing the charging and discharging of the plurality of batteries included in the first battery group compared to the charging and discharging of the plurality of batteries included in the second battery group. In the battery management method, For each battery in the first battery group with a low degree of degradation, it is determined whether the state of charge (SOC) of that battery is within the SOC range where battery degradation progresses slowly. This SOC range is predetermined to be 40% to 60% based on the characteristics of the battery. If the SOC of a battery in the first battery group that has a low degree of degradation is within the range where degradation is progressing slowly, the battery is electrically disconnected from the power system.

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