Battery management system and battery management method

Abstract

A battery management system and a battery management method are provided. A battery well (2) includes: a storage library (21) that stores a plurality of batteries; a power conversion device (an AC / DC converter (22) and a DC / DC converter (23)) that is electrically connected between the plurality of batteries stored in the storage library (21) and a power system (5) and is capable of bidirectional power conversion operation; and a server (20) that causes the plurality of batteries to charge and discharge by controlling operation of the power conversion device in accordance with a DR request from the power system (5). The server (20) suppresses charging and discharging of a battery of a high-demand level among the plurality of batteries, as compared to charging and discharging of a battery of a low-demand level, based on a level of demand determined in accordance with a level related to a deterioration degree of the battery.

Description

Technical Field

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

[0002] Japanese Unexamined Patent Application Publication No. 2018-205873 describes prompting a user of an electric vehicle having a storage battery suitable for a power storage system to replace the storage battery. Summary of the Invention

[0003] In recent years, the popularity of vehicles equipped with drive batteries has rapidly increased. Therefore, the number of used batteries (Japanese: chuko denchi) recovered due to the replacement, disassembly, etc. of these vehicles has increased. From the perspective of promoting sustainable development goals (SDGs: Sustainable Development Goals), it is required to reuse used batteries by manufacturing new battery packs using the recovered used batteries. The inventors have focused on the case where the following problems may occur when reusing used batteries.

[0004] Batteries are stored at logistics bases, etc. during the period of waiting for use. Costs are incurred to properly store the batteries. In addition, it may take a certain amount of time (storage period) from the storage of the batteries to the shipment for the next use. Therefore, it is preferable to effectively utilize the storage period of the batteries.

[0005] It is conceivable to classify batteries according to the degree of deterioration. Depending on the use, etc., the required grade also differs. Therefore, there may be a grade with relatively high demand, and on the other hand, there may be a grade with relatively low demand. Preferably, in the battery management system, a corresponding number of batteries are ensured in stock for each grade according to the demand. On the other hand, the battery management system side cannot adjust what grade of batteries are recovered from the market. In addition, during the storage period of the battery management system, the deterioration of the batteries also accelerates, and thus the grade may decrease.

[0006] The present disclosure has been made to solve the above problems, and an object of the present disclosure is to ensure batteries of a grade corresponding to the demand while effectively utilizing the storage period of the batteries.

[0007] (1) A battery management system according to one aspect of the present disclosure includes: a storage warehouse that stores a plurality of batteries; a power conversion device that is electrically connected between the plurality of batteries stored in the storage warehouse and a power system; and a control device that controls the operation of the power conversion device by responding to a demand request from the power system, thereby charging and discharging the plurality of batteries. The control device suppresses the charging and discharging of batteries of a grade with high demand compared to the charging and discharging of batteries of a grade with low demand among the plurality of batteries, based on the level of demand determined according to the grade related to the degree of deterioration of the batteries.

[0008] (2) The control device makes the charge and discharge power of the high-demand battery during the predetermined period smaller than that of the low-demand battery during the predetermined period.

[0009] (3) The control device makes the charging and discharging frequency of the high-demand battery less than that of the low-demand battery.

[0010] (4) 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 to disconnect batteries with higher demand levels from the power system.

[0011] In the structures described in (1) to (4) above, the charging and discharging of high-demand batteries is suppressed compared to that of low-demand batteries. More specifically, for high-demand batteries, the charging and discharging power or frequency is reduced compared to that of low-demand batteries. Alternatively, the high-demand batteries are disconnected from the power system. As a result, the charging and discharging of high-demand batteries, which correspond to the demand response requirements from the power system, is suppressed, and thus the degradation associated with the charging and discharging of these batteries is suppressed. Consequently, the batteries can be maintained at the high-demand level, thus ensuring the availability of batteries that meet demand requirements.

[0012] (5) When the SOC of the high-demand battery is within a predetermined SOC range that can suppress the aggravation of degradation, the control device suppresses the charging and discharging of the high-demand battery compared to the charging and discharging of the low-demand battery.

[0013] If the battery's SOC is outside the aforementioned SOC range, even if the charging and discharging of a high-demand battery is suppressed, degradation may still accelerate during storage. In the structure described in (5) above, when the SOC of the high-demand battery is within a predetermined SOC range that can suppress the aggravation of degradation, the charging and discharging of the high-demand battery is suppressed. As a result, the aggravation of degradation of the battery during storage can be suppressed, and the battery can be more reliably maintained as a high-demand battery.

[0014] (6) A control device that suppresses the charging and discharging of batteries of the same class determined by the customer, compared with the charging and discharging of batteries of the same class not determined by the customer.

[0015] In the structure described in (6) above, for batteries whose rating is determined by the customer, charging and discharging are suppressed compared to batteries of the same rating that are not determined by the customer. This suppresses the escalation of deterioration during the storage period up to the sale of the battery. Therefore, the battery rating can be maintained at the level determined by the customer at that point in time.

[0016] (7) Other aspects of the battery management method disclosed herein include a battery management method using a server. This method includes the step of the server charging and discharging multiple batteries stored in a vault according to demand response requirements from a power system. The charging and discharging step includes the following steps: the server, based on a level of demand determined according to a level related to the degree of battery degradation, suppresses the charging and discharging of batteries with higher demand levels compared to the charging and discharging of batteries with lower demand levels among the multiple batteries.

[0017] According to the method described in (7) above, the same structure as described in (1) above can ensure the battery of the required grade.

[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 form of the logistics of the battery pack in this embodiment.

[0020] Figure 2 This diagram illustrates an example of a used battery being stored in a vault.

[0021] Figure 3 This is a flowchart illustrating an outline of the operational procedures for reusing second-hand batteries.

[0022] Figure 4 This is a system structure diagram showing the electrical structure of the battery cellar.

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

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

[0025] Figure 7 This is a conceptual diagram illustrating another example of the 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 the 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 steps related to charge / discharge suppression in this embodiment.

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

[0029] Figure 11 This is a flowchart illustrating the third example of the processing steps 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 battery wells and the power system. Detailed Implementation

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

[0033] In this disclosure and embodiments, 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 individual cells (single cells).

[0034] Generally, battery pack "reuse" falls into three categories: reuse, reassembly, and material recycling. In the case of reuse, the recycled battery pack undergoes necessary outgoing checks and is shipped directly as reused products. In the case of reassembly, the recycled battery pack is temporarily disassembled into modules. Then, usable modules (or modules usable after performance recovery) from the disassembled modules are combined to manufacture new battery packs. The newly manufactured battery packs undergo outgoing checks and are shipped as reassembled products. In contrast, in material recycling, renewable materials (resources) are extracted from each individual battery cell. Recycled battery packs are not used to create other battery packs.

[0035] In the embodiments described below, the battery pack recovered from the vehicle is temporarily disassembled into modules. Then, various processes are performed on a module-by-module basis. That is, in the following description, reusable second-hand batteries refer to modules that can be reassembled. However, disassembly of modules is not mandatory. Depending on the battery pack's structure or degree of degradation, it may also be reused without disassembling it 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 labeled with 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 configuration of the battery pack's logistics in this embodiment. Hereinafter, Figure 1 The logistics model shown is called the "battery logistics model". The battery logistics model 100 includes a recycler 1, a battery well 2, a customer (sales target) 3, a recycling plant 4, a power system 5, and a distributed energy resource (DER) 6.

[0040] Recycler 1 collects used battery packs (second-hand batteries 9) from multiple vehicles. Recycler 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), or track the circulation path of the used battery 9.

[0041] Battery well 2 refers to a facility, similar to a wine cellar where wine bottles are stored under controlled temperature and humidity, used for the proper management of used batteries 9 collected by recycling company 1. Battery well 2 is located in... Figure 1 The example shown is a logistics hub located near the harbor. Battery well 2 includes a server 20 that manages data related to used batteries 9, and multiple vaults (storage units) 21. Furthermore, battery well 2 is equivalent to the "battery management system" of this disclosure. Batteries stored in battery well 2 are not limited to used batteries, but may also include new batteries.

[0042] Figure 2 This diagram illustrates an example of a used battery 9 being stored in storage room 21. (See diagram for example.) Figure 2 As shown, multiple storage vaults 21 are configured within the building of the battery well 2. Each of the multiple storage vaults 21 is configured to store a large number of used batteries 9. In this embodiment, the battery well 2 conducts a degradation evaluation test on each of the used batteries 9 stored in the storage vault 21, the details of which will be described later. Then, based on the results of the degradation evaluation test, the battery well 2 determines whether each used battery 9 is reusable or not (suitable for reuse or unsuitable for reuse).

[0043] Return to Figure 1Customer 3 purchases used batteries 9 that are determined to be reusable by battery well 2. Customer 3 may include sales stores 31 that sell used batteries 9 for use in vehicles and users 32 that use them as fixed equipment in factories, buildings, etc. In addition, customer 3 may also include sales stores 33 that sell used batteries 9 as supplies (replacement parts for maintenance and repair).

[0044] The recycling plant 4 recycles materials used to regenerate second-hand batteries 9 that are determined to be unusable by the battery well 2 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 generation operator and a transmission and distribution operator. The power company is equivalent to a regular transmission and distribution operator and also acts as the manager of power system 5, maintaining and managing it. An operator server 50 is installed in power system 5. The operator server 50 belongs to the power company and manages the power supply and demand of power system 5. Server 20 and operator server 50 are configured to communicate bidirectionally.

[0046] DER6 is a relatively small-scale power equipment installed at a logistics base (or its surrounding area) where a battery well 2 is located, and capable of receiving and transmitting power between the battery well 2 and the battery well 2. DER6 includes, for example, generator-type DER and energy storage-type DER.

[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 solar power generation equipment (solar panels), but natural variable power sources can also replace solar power generation equipment or include wind power generation equipment. On the other hand, generators are power generation equipment that are not dependent on 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 power storage systems and thermal storage systems. Power storage systems are stationary energy storage devices that store electricity generated by natural and fluctuating power sources. Power storage systems can also be power-to-gas (PTO) devices that use electricity to produce gaseous fuels (hydrogen, methane, etc.). Thermal storage systems include a heat storage tank located between a heat source and a load, configured to temporarily store a liquid medium within the tank in a temperature-controlled state. By using a thermal storage system, the generation and consumption of heat can be staggered over time. Therefore, for example, heat generated by operating a heat source machine at night by consuming electricity can be stored in the heat storage tank and consumed during the day for air conditioning.

[0049] Thus, the used batteries 9 collected by recycling operator 1 are stored in battery well 2 while awaiting delivery to customer 3 or recycling plant 4. However, proper storage of the used batteries 9 in battery well 2 incurs maintenance costs (operating costs). Moreover, a certain amount of time may be required between the receipt of the collected used batteries 9 and their delivery to customer 3 or recycling plant 4. Therefore, it is preferable to effectively utilize the storage period of the used batteries 9 in battery well 2.

[0050] In this embodiment, in addition to functioning as a storage location for used batteries 9, battery well 2 also functions as a virtual power plant (VPP). Therefore, the opportunity for used batteries 9 to charge and discharge simultaneously influences the degradation assessment of used batteries 9, which determines their reuse method, and the 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, the degradation assessment of used batteries 9, and the adjustment of the power supply and demand balance based on used batteries 9 are all performed in a "three-in-one" manner within battery well 2.

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

[0052] Figure 3 This is a flowchart showing an outline of 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 well 2 (S1).

[0053] In this embodiment, the server 20 performs a degradation evaluation test (performance check) on each used battery 9 while it is stored in the storage vault 21 (S2). The server 20 evaluates the degree of degradation for each used battery 9 based on electrical characteristics such as full charge capacity and internal impedance (e.g., AC impedance). Then, based on the results of the degradation evaluation test, the server 20 determines whether each used battery 9 is reusable or not (S3).

[0054] In this embodiment, the used battery 9 is graded 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 the buying and selling price of the used batteries 9 in relation to their grade, and ensures the quality of the used batteries 9 according to their grade. Therefore, the used batteries 9 that have passed through battery well 2 can circulate smoothly in the market. Furthermore, used batteries 9 with a full-charge capacity lower than a specified value are graded as lower than C (referred to as Re) and used for material recycling.

[0055] If the battery is determined to be reusable ("Yes" in S3), the work process proceeds to the performance recovery process (S4). In the performance recovery process, a treatment 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 process can be omitted. Alternatively, based on the results of the degradation evaluation test, performance recovery treatment may be performed on used batteries 9 with a high degree of degradation (significant performance reduction), while performance recovery treatment may not be performed on used batteries 9 with a low degree of degradation (minimal performance reduction).

[0056] Next, a new battery pack is manufactured (reassembled) using the used battery 9 whose performance has been restored through the performance restoration process (S5). The battery pack is basically reassembled from the used battery 9 whose performance has been restored through the performance restoration process, but it may also include used batteries 9 whose performance restoration process has been omitted, and may also include new batteries (new modules). After that, the battery pack is sold and shipped to customer 3 (S6).

[0057] Based on the results of the degradation evaluation test, if the battery is determined to be unusable ("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.

[0058] Thus, during the period from when the used battery 9 is collected by the recycling operator 1 until it is delivered to the customer 3 or the recycling plant 4, it is stored in the battery well 2, during which a degradation evaluation test is conducted. In the degradation evaluation test, the used battery 9 is charged and discharged to measure its electrical characteristics, such as its full-charge capacity. In this embodiment, the power received between the battery well 2 (and DER6) and the power system 5 is used in this charging and discharging. Therefore, the battery well 2 functions as a VPP (one of the DERs), contributing to the load balancing of the power system 5. More specifically, during periods when there is a surplus of supply in the power system 5 relative to demand, the battery well 2 absorbs the surplus power by charging the used battery 9. On the other hand, when there is a shortage of supply in the power system 5 relative to demand, the battery well 2 alleviates the power shortage by releasing an amount of power from the used battery 9 corresponding to the shortage.

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

[0060] <Electrical Structure of Battery Wells>

[0061] Figure 4 This is a system structure diagram showing the electrical structure of battery well 2. Battery well 2 includes, for example, a storage tank 21, an AC / DC converter 22, a DC / DC converter 23, and a server 20. Furthermore, in... Figure 4 For ease of illustration on paper, only one vault 21 is shown in the diagram, but if... Figure 2 As shown, a typical battery well 2 has multiple vaults 21.

[0062] Storage room 21 stores multiple used batteries. Figure 4 In this example, multiple used batteries 9 are connected in parallel, but this is merely an illustration, and the connection method of the multiple used batteries 9 is not particularly limited. Multiple used batteries 9 can also be connected in series, or a combination of series and parallel connections. The storage tank 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 and outputs its detection value to server 20. Furthermore, if temperature is used in the degradation evaluation of the used battery 9, storage tank 21 may also include a temperature sensor (not shown). Additionally, each sensor may be a sensor installed on 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, allowing the used battery 9 to be removed from the storage vault 21. Furthermore, relay 213 corresponds to the "switching device" of this disclosure.

[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 used batteries 9 stored in the storage facility, according to control commands (charge / discharge commands) from server 20. More specifically, AC / DC converter 22 converts AC power supplied from power system 5 into DC power for charging used batteries 9. Additionally, AC / DC converter 22 converts DC power discharged from used batteries 9 into AC power supplied to power system 5.

[0066] DC / DC converter 23 is electrically connected between AC / DC converter 22 and storage tank 21, and also electrically connected between DER6 and storage tank 21. DC / DC converter 23, like AC / DC converter 22, is configured to perform bidirectional power conversion 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, or 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 for various input and output signals (not shown). Server 20 performs various controls based on signals received from various sensors and programs and mappings stored in memory. 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 in battery well 2 used for managing used batteries 9.

[0069] Figure 5 This diagram illustrates an example of the data structure for battery data. Battery data is stored, for example, in a mapped format. The battery data includes parameters such as identification information (battery ID) for identifying the used battery 9, the model of the used battery 9, manufacturing date, current SOC (State of Charge), full charge capacity, rating, degradation evaluation date and time (the latest date and time of the degradation evaluation test), and storage location (identification information of the storage facility containing the used battery 9). Furthermore, the battery data may also include parameters other than those mentioned above (such as the internal impedance of the used battery 9, an index ΣD representing the deviation 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 This section illustrates an example of the evaluation method. The degradation evaluation department 202 grades the used battery 9 based on the results of the degradation evaluation test.

[0071] The power adjustment unit 203 performs power adjustments between battery well 2 (and DER6) and power system 5. More specifically, server 20 selects from multiple used batteries 9 to respond to power from carrier server 50 (see reference). Figure 1 The power regulating 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 in accordance with the demand response (DR) requirements. Figure 13 Here is an example illustrating this control method.

[0072] 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 well 2 and the power system 5 performed by the power adjustment unit 203. More specifically, the timing adjustment unit 204 adjusts the timing so that the degradation evaluation test of the used battery 9 is performed in a manner that matches the timing of the DR of the battery well 2 in response to the DR request from the operator server 50. Furthermore, the operation performed in accordance with the DR of the battery well 2 is not limited to the degradation evaluation test of the used battery 9; performance recovery processing may also be performed in addition to the degradation evaluation test (see [reference]). Figure 3 S4).

[0073] Display unit 205 displays battery data based on the operation of the manager of battery well 2 (or the operator working in battery well 2). Figure 5 In addition, 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. Furthermore, the display unit 205 displays the status of the used battery 9 selected and charged / discharged by the power adjustment unit 203. This allows the manager to monitor the power adjustment status between the battery well 2 and the power system 5.

[0074] Furthermore, server 20 is equivalent to the "control device" of this disclosure. AC / DC converter 22 and DC / DC converter 23 are equivalent to the "power conversion device" of 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 conversely, grades with relatively low demand. Preferably, in battery well 2, a quantity of used batteries 9 corresponding to the reuse demand for each grade is maintained in stock. However, it is not possible to adjust the grade of used batteries 9 recycled from the market at the battery well 2 level. Furthermore, the deterioration of used batteries 9 during storage at battery well 2 can accelerate, potentially leading to a lower grade. In particular, in battery well 2, the used batteries 9 are repeatedly charged and discharged for power adjustments with the power system 5, thus easily accelerating their deterioration.

[0077] Therefore, in this embodiment, server 20 obtains demand forecasts for each grade of used batteries 9 based on actual sales performance and other data. Furthermore, server 20 suppresses the charging and discharging of used batteries 9 in grades with relatively high demand, compared to the charging and discharging of used batteries 9 in grades with relatively low demand. This suppresses the deterioration of used batteries 9 associated with charging and discharging, maintaining the grade of these used batteries 9 at a high-demand level. As a result, it ensures a larger inventory of "best-selling" grade used batteries 9.

[0078] Figure 6 This is a conceptual diagram illustrating an example of the 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 the 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 second-hand 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 power from battery well 2 (second-hand battery 9) to power system 5.

[0079] Here, as an example, let's consider a scenario where, among levels S to C, the demand for level A is the highest and the demand for level C is the lowest. For example... Figure 6 As shown, the charge / discharge amount (charge / discharge power) of the high-demand Grade A used battery 9 during a predetermined period can be made smaller than that of the low-demand Grade C used battery 9 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 of the charge / discharge power (e.g., peak value) (see reference). Figure 6 ), or as Figure 7 Adjust the length of the charge / discharge period as shown. You can also adjust both the charge / discharge power and the length of the charge / discharge period. Additionally, as shown... Figure 8 As shown, the charge / discharge frequency of the high-demand Grade A used battery 9 can also be reduced compared to the low-demand Grade C used battery 9 (second control). Although not shown, regarding Grade A used battery 9, both the charge / discharge amount and the charge / discharge frequency can be suppressed compared to Grade C used battery 9. That is, the first control and the second control can also be used together.

[0080] <Charge and discharge suppression process>

[0081] Figure 9This is a flowchart illustrating a first example of the processing steps related to charge / discharge suppression in this embodiment. This flowchart (and other flowcharts described later) is invoked and executed from the main routine (not shown) when predetermined conditions are met. Each step is implemented through software processing of the server 20, but may also be implemented through hardware (circuit) configured within the server 20. Hereinafter, the steps will be abbreviated as S.

[0082] In S11, server 20 obtains demand forecasts for each grade of used batteries 9. The demand for each grade is primarily based on past sales performance of used batteries, but market trends (such as price trends) can also be considered. Server 20 can forecast the demand for each grade of used batteries 9 itself, or it can obtain forecasts based on external servers (not shown).

[0083] In S12, server 20 calculates the electrical force required for power adjustment between battery well 2 and power system 5. Hereinafter, this electrical force will be referred to as the battery well adjustment amount, also denoted as kWh (bat). Figure 10 This section details an example of how to calculate the battery well adjustment amount in kWh (bat).

[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 well adjustment amount ΔkWh(bat). If there is no margin, that is, if the battery well adjustment amount ΔkWh(bat) is greater than the amount of electricity that can be charged and discharged using all the used batteries 9 (in S13, this is "No"), in order to make the amount of electricity charged and discharged in battery well 2 close to the battery well 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 of safety, that is, when the battery well adjustment amount ΔkWh(bat) is less than the charge / discharge capacity that can be achieved using all the used batteries 9 ("Yes" in S13), the battery well adjustment amount ΔkWh(bat) can be met even without charging / discharging all the used batteries 9. In this case, server 20 determines the charge / discharge amount and frequency of each used battery 9 according to its level (S14). Specifically, server 20 will select the higher-demand level (in...) Figure 6 In the example, the charge / discharge capacity of the used battery 9 (grade A) is determined to be smaller than that of the used battery 9 (grade C), which has a lower demand.

[0086] Figure 10This is a flowchart illustrating a second example of the processing steps related to charge / discharge suppression in this embodiment. The processes in S21-S23 and S29 are respectively related to... Figure 9 The processing of S11 to S13 and S19 shown is the same, so it will not be explained again. For example... Figure 10 As shown, server 20 can also determine the charging and discharging frequency of high-demand grade used battery 9 to be less than that of low-demand grade used battery 9 (S24).

[0087] In this way, compared with low-demand used batteries 9, for high-demand grade used batteries 9, by reducing the amount of charging and discharging used for power regulation or reducing the charging and discharging frequency, the degradation accompanying charging and discharging can be suppressed. Therefore, the high-demand grade can be maintained, and thus sufficient inventory of high-demand grade used batteries 9 can be ensured.

[0088] Figure 11 This is a flowchart illustrating the third example of the processing steps related to charge / discharge suppression in this embodiment. The processing steps S31 to S33 and S39 are respectively related to... Figure 9 The processes S11 to S13 and S19 shown are the same, so they will not be described again. When the total amount of electricity that can be charged and discharged using all the second-hand batteries 9 is sufficient relative to the battery well adjustment amount kWh (bat) (yes in S33), the server 20 causes the process to proceed to S34.

[0089] In step S34, server 20 determines whether the State of Charge (SOC) of each used battery 9, which is classified as high-demand, is within a predetermined SOC range. This SOC range is determined in advance based on the characteristics of the used battery 9, as it represents a slower rate of degradation. Typically, if the SOC of a secondary battery is too high (e.g., above 80%) or too low (e.g., below 20%), the degradation of the secondary battery is more likely to accelerate. Therefore, the aforementioned SOC range is preferably an intermediate range (e.g., an SOC range of 40% to 60%).

[0090] If the SOC of a certain used battery 9 in the high-demand grade is in the range of SOC where the degradation is slow ("Yes" in S34), the server 20 will open the relay 213 corresponding to that used battery 9 to disconnect the used battery 9 from the power system 5 (S35).

[0091] Furthermore, if too many used batteries 9 are disconnected from the power system 5, the charging and discharging power from the battery well 2 may be insufficient relative to the battery well adjustment amount (kWh(bat)). Therefore, it is preferable that the server 20 takes the battery well adjustment amount (kWh(bat)) into account when controlling the relay 213. That is, it is preferable that the server 20 adjusts 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 well adjustment amount (kWh(bat)) remains in a state of being 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 batteries 9 (used batteries 9 outside the SOC range where SOC degradation is slow) that are electrically connected to power system 5 and are of high demand level. Regardless of the SOC range, server 20 charges and discharges the used batteries 9 of low demand level. Furthermore, the higher the temperature of the used batteries 9, the more easily they deteriorate. Therefore, server 20 can also impose certain limits on the charging and discharging current so that the used batteries 9 do not become excessively hot due to the heat generated during charging and discharging.

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

[0094] Furthermore, S34 processing can also be applied to Figure 9 and / or Figure 10 The flowchart shows that when the SOC of the used battery 9 is in a range where the degradation is slow, the server 20 can reduce the charge and discharge amount or the charge and discharge frequency of the high-demand used battery.

[0095] In addition, regarding Figures 9-11 In any of the examples, server 20 could also suppress the charging and discharging of used batteries 9 of the same grade determined by the customer, compared to the charging and discharging of used batteries not determined by the customer. That is, server 20 could also suppress the charging and discharging of used batteries 9 determined by the customer, even if they are of a lower grade (e.g., grade C). As a result, it is possible to suppress the aggravation of deterioration during the storage period until the sale of the used battery, and thus prevent the grade from decreasing from the point of customer determination.

[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 that have not undergone degradation evaluation exist, 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 grading unit 75.

[0098] The current accumulation unit 71 calculates the cumulative value (cumulative current amount) ΔAh (unit: Ah) of the current charged and discharged in the used battery 9 during the period from the time the start condition for current accumulation is met to the time the end condition for current accumulation is 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, in the case of increasing DR (power demand increase request), the used battery 9 is charged to increase the power demand of the battery well 2, and the charging current at this time is accumulated. On the other hand, in the case of decreasing DR, the used battery 9 is discharged to reduce the power demand of the battery well 2, and the discharging current at this 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 impedance 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. 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 impedance 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 pre-existing characteristic curve (OCV-SOC curve) representing the SOC dependence of OCV. Therefore, 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 by referring to the OCV-SOC curve, 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, the initial full charge capacity C0 is known according to the specifications of the used battery 9, so 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 grading unit 75.

[0104] C=ΔAh / ΔSOC×100…(2)

[0105] The grading unit 75 grades the used battery 9 according to its full charge capacity C. The grading unit 75 can record the grading date and time as the degradation evaluation date and time 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, when a customer 3 receives a request to purchase a used battery 9, the operator working in the battery well 2 can retrieve a used battery 9 of the grade required by the customer 3 from the storage location. By appropriately retrieving used batteries for sale from the storage unit 21, situations where the storage unit 21 is full can be prevented.

[0107] Furthermore, the method for calculating the full charge capacity C described above is merely one example. In calculating the full charge capacity C, any method can be used as long as the voltage VB and current IB detected during the charging and discharging of the used battery 9 are employed. Additionally, the grading unit 75 can determine the grade of the used battery 9 based on other characteristics (such as the internal resistance R of the used battery 9, the index ΣD indicating the deviation of the electrolyte concentration in the lithium-ion battery, etc.) instead of the full charge capacity C. Furthermore, the grading unit 75 can also determine the grade of the used battery 9 based on the duration of charging and discharging and / or the number of times the used battery 9 has been charged and discharged. Although the accuracy may be slightly reduced, the grading unit 75 can also determine the grade of the used battery 9 based on the elapsed time since its manufacture. The grading 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 battery well 2 and power system 5. In this example, for ease of understanding, it is assumed that DER6 is a power generation type DER (especially a naturally fluctuating power source such as solar power generation equipment). The power adjustment unit 203 includes an overall adjustment calculation unit 81, a DER adjustment calculation unit 82, a battery well adjustment 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 the DR request from the operator server 50 and calculates the total power required for power adjustment during a predetermined period (e.g., 30 minutes) using battery well 2 and DER6. Hereinafter, this power is 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 well adjustment calculation unit 83.

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

[0112] The battery well adjustment calculation unit 83 calculates the electrical power required for power adjustment when using battery well 2 based on the kWh(total) from the total adjustment calculation unit 81 and the kWh(DER) from the DER adjustment calculation unit 82. Hereinafter, this electrical power is referred to as the battery well adjustment amount, also denoted as kWh(bat). For example, the battery well adjustment calculation unit 83 can calculate the battery well adjustment amount kWh(bat) as the difference between the two electrical powers, i.e., ΔkWh = kWh(total) - kWh(DER). The battery well adjustment calculation unit 83 outputs the calculated kWh(bat) to the used battery selection unit 84.

[0113] The used battery selection unit 84 obtains rechargeable and dischargeable electrical power (see reference) for each of the multiple used batteries 9 stored in multiple storage compartments 21. Figure 5 (Battery data). The used battery selection unit 84 selects used batteries from multiple used batteries 9 for use in power adjustment based on the kWh (bat) calculated from the battery well adjustment amount calculation unit 83. When kWh (bat) > 0, the power shortage in the power system 5 is supplemented by discharging from the battery well 2. Therefore, the used battery selection unit 84 selects a number of used batteries 9 capable of discharging more than kWh (bat). On the other hand, when kWh (bat) < 0, the remaining power in the power system 5 is absorbed by charging the battery well 2. Therefore, the used battery selection unit 84 selects a number of used batteries 9 capable of charging more than kWh (bat) (absolute value). When selecting used batteries 9, priority is given to charging and discharging used batteries 9 with low demand, while charging and discharging used batteries 9 with high demand is avoided as much as possible. Regarding this process, Figures 9-11 The details have been described in detail in the previous section, so they will not be repeated here. The used battery selection unit 84 outputs the selected used battery 9 and the power allocated to each selected used battery 9 (the power adjusted by each used battery 9) to the conversion calculation unit 85.

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

[0115] Based on the calculation results of the conversion calculation unit 85, the instruction generation unit 86 generates charge / discharge commands for the AC / DC converter 22 and the DC / DC converter 23, and also generates on / off commands for the relay 213. More specifically, the instruction generation unit 86 generates on / off commands by electrically connecting the selected used battery 9 to the DC / DC converter 23 and electrically disconnecting the unselected used battery 9 from the DC / DC converter 23. The instruction generation unit 86 generates charge / discharge commands by charging and discharging the total amount of power allocated to the selected used battery 9.

[0116] Furthermore, it is confirmed that, Figure 13 The power adjustment method shown is merely an example. In this example, it is assumed that DER6 is a power generation type DER, specifically a naturally fluctuating power source whose power generation cannot be controlled. Therefore, the battery well adjustment amount calculation unit 83 calculates the battery well 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). In other words, in this example, after determining the DER adjustment amount kWh(DER), the final power adjustment is performed using the battery well adjustment amount kWh(bat). However, for example, if DER6 includes a storage type DER, the battery well adjustment amount calculation unit 83 may also allocate the total adjustment amount kWh(total) into the DER adjustment amount kWh(DER) and the battery well adjustment amount kWh(bat), and perform power adjustment using both the DER adjustment amount kWh(DER) and the battery well adjustment amount kWh(bat).

[0117] As described above, in this embodiment, the degree of degradation of each used battery 9 is evaluated while it is stored in the storage vault 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 degradation is primarily based on DR requirements from the operator server 50. Additionally, when there are many used batteries 9, a large amount of power is charged and discharged, and this large power is transferred between the battery well 2 and the power system 5 according to the DR requirements from the operator server 50. Therefore, the operating company of the battery well 2 can receive payment (reward) from the power company, and this payment can be used as operating costs for the battery well 2. Alternatively, the operating company of the battery well 2 can recover a portion of the initial investment (initial cost) of the battery well 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 high-demand grade used batteries 9 is suppressed compared to low-demand grade used batteries 9. Therefore, the degradation of high-demand grade used batteries 9 during charging and discharging can be suppressed, thus maintaining their high-demand grade. Therefore, it is possible to ensure that used batteries 9 meet the requirements for reuse.

[0119] Embodiments of the present invention have been described, but should be considered as illustrative rather than restrictive in all respects. The scope of the invention is set forth in the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A battery management system, wherein, have: A vault, wherein multiple batteries are stored; A power conversion device, which is electrically connected between the plurality of batteries stored in the vault and the power system; as well as A control device controls the operation of the power conversion device according to demand response requirements from the power system, thereby charging and discharging the plurality of batteries. The control device, based on a level of demand determined according to the degree of battery degradation, suppresses the charging and discharging of batteries with higher demand levels compared to the charging and discharging of batteries with lower demand levels among the plurality of batteries. The control device, for high-demand batteries, disconnects the battery from the power system when the battery's SOC is within the range of 40% to 60%, thus preventing the battery from charging and discharging. For low-demand batteries, it allows the battery to charge and discharge regardless of its SOC. The control device suppresses the charging and discharging of batteries of the same class that are not customer-determined, compared to the charging and discharging of batteries that are not customer-determined, so that charging and discharging is suppressed for customer-determined batteries, even for those of lower demand classes.

2. The battery management system according to claim 1, wherein, The control device causes the charge / discharge power of the high-demand battery during a predetermined period to be less than that of the low-demand battery during the same predetermined period.

3. The battery management system according to claim 1, wherein, The control device causes the high-demand battery to charge and discharge at a lower frequency than the low-demand battery.

4. The battery management system according to claim 1, wherein, The battery management system also includes a switching device configured to switch the electrical connection and disconnection between each of the plurality of batteries and the power system. The control device controls the switching device in a manner that electrically disconnects the high-demand battery from the power system.

5. A battery management method, which uses a server battery management method, wherein, The battery management method includes the steps of the server charging and discharging multiple batteries stored in a vault according to demand response requirements from the power system. The charging and discharging steps include the following steps: The server, based on the level of demand determined according to the degree of battery degradation, suppresses the charging and discharging of batteries with high demand levels compared to the charging and discharging of batteries with low demand levels among the plurality of batteries. For batteries with high demand, the battery is disconnected from the power system to prevent charging and discharging, provided that the battery's SOC is in the range of 40% to 60%. For batteries with low demand, the battery is charged and discharged regardless of its SOC. Compared to the charging and discharging of batteries of the same class that are not customer-determined, the charging and discharging of batteries of the same class that are customer-determined are suppressed, so that the charging and discharging of customer-determined batteries, even those of the lower demand class, are also suppressed.

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