Battery management system and battery management method

Abstract

This invention provides a battery management system and a battery management method. The battery well (2) comprises: a storage vault (21) storing multiple used batteries (9); an AC / DC converter (22) and a DC / DC converter (23) electrically connected between the multiple used batteries (9) stored in the storage vault (21) and a power system (5); and a server (20) controlling the AC / DC converter (22) and the DC / DC converter (23). The server (20) controls the AC / DC converter (22) and the DC / DC converter (23) according to demand response requirements from the power system (5), and evaluates the degree of degradation of each of the multiple used batteries (9) based on the voltage and current of each of the multiple used batteries (9) charged and discharged by the AC / DC converter (22) and the DC / DC converter (23).

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 their batteries. Summary of the Invention

[0003] In recent years, the number of vehicles equipped with battery packs for driving has increased rapidly. As a result, the number of batteries recycled due to the replacement and dismantling of these vehicles has increased. Typically, batteries are stored at logistics locations while awaiting further processing (sales, recycling, etc.).

[0004] There are costs associated with properly storing batteries. Furthermore, there may be a certain amount of time (storage period) between the time batteries are received into the warehouse and their release to subsequent processes. Therefore, it is preferable to utilize the battery storage period effectively.

[0005] This disclosure was made to solve the above-mentioned problems, and the purpose of this disclosure is to effectively utilize the storage period of the battery.

[0006] (1) The battery management system of the first aspect of this disclosure comprises: a storage vault storing a plurality of batteries; a power conversion device electrically connected between the plurality of batteries stored in the storage vault and a power system; and a control device controlling the power conversion device. The control device controls the power conversion device according to demand response requirements from the power system and evaluates the degree of degradation of each of the plurality of batteries based on the voltage and current of each of the plurality of batteries being charged and discharged by the power conversion device.

[0007] (2) The power conversion device is configured to perform bidirectional power conversion operations. When the demand response request is an increase in power demand, the control device controls the power conversion device to charge multiple batteries and evaluates the degree of degradation of the multiple batteries during the charging period. On the other hand, when the demand response request is a decrease in power demand, the control device controls the power conversion device to discharge multiple batteries and evaluates the degree of degradation of the multiple batteries during the discharging period.

[0008] In the structures described in (1) and (2) above, the control device evaluates the degree of degradation of each battery while the batteries are stored in a storage facility. Thus, the degradation evaluation is completed during the battery storage period, saving time that would otherwise be spent on separate degradation evaluations. Furthermore, the control device evaluates the degradation of each battery by utilizing the charging and discharging opportunities provided by the power system, based on demand response requirements from the power system. By responding to demand response requirements, compensation can be obtained from the power system manager (usually the power company). Therefore, according to the structures described in (1) and (2) above, the battery storage period can be effectively utilized in terms of both time and money.

[0009] (3) The storage facility includes multiple relays configured to switch the electrical connection and disconnection between each of the multiple batteries and the power conversion device. Upon receiving a demand response request, the control device controls the multiple relays in such a manner that the multiple batteries being charged and discharged by the power conversion device include at least one of batteries whose degradation level has not been evaluated and batteries for which a period longer than a predetermined period has elapsed since the last degradation level evaluation.

[0010] In the structure described in (3) above, the control device enables at least one of the multiple batteries that are charged and discharged according to demand response requirements: batteries whose degradation level has not been evaluated and batteries for which a period longer than a predetermined period has elapsed since the last degradation level evaluation. By preferentially selecting these batteries, it is possible to evaluate the degradation level of the batteries whose degradation level has not yet been evaluated and update the degradation level evaluation results to the latest state. Therefore, battery quality management can be improved.

[0011] (4) The storage facility includes multiple relays configured to switch the electrical connection and disconnection between each of the multiple batteries and the power conversion device. Upon receiving a demand response request, the control device controls the multiple relays in a manner that allows the charging and discharging of the number of batteries that meet the demand response request from the multiple batteries.

[0012] In the structure described in (4) above, the control device charges and discharges the number of batteries sufficient to meet the demand response requirement upon receiving such a request. By fully responding to the demand response requirement, the rewards received from the power system administrator can be increased.

[0013] (5) The control device classifies the multiple batteries according to their degree of deterioration.

[0014] (6) The battery management system also includes a monitor. The control device selects the battery grade that meets the requirements of the sales target from multiple batteries stored in the storage room and notifies the operator of the selected battery using the monitor.

[0015] In the structures of (5) and (6) above, the control device classifies the batteries. Thereby, it is possible to set the selling price of the batteries for each grade and ensure the quality of the batteries according to the grade. Therefore, it is possible to make the batteries flow smoothly in the market. In addition, it is possible to determine whether the requirements of the sales target are met by the grade, so the management of the batteries becomes easy.

[0016] (7) The control device evaluates the degree of deterioration of multiple batteries based on the full charge capacity.

[0017] (8) The battery management method according to the second aspect of the present disclosure is a battery management method using a server, including a first step and a second step. The first step is a step in which the server charges and discharges multiple batteries stored in the storage facility according to a demand response request from the power system. The second step is a step in which the server evaluates the degree of deterioration of each of the multiple batteries based on the voltage and current of each of the multiple batteries charged and discharged in the charging and discharging step.

[0018] According to the method of (8) above, similarly to the structure of (1) above, it is possible to effectively utilize the storage period of the batteries.

[0019] (9) The battery management method further includes a step in which the server selects batteries that meet the requirements of the sales target from the multiple batteries stored in the storage facility.

[0020] According to the method of (9) above, by appropriately selecting and taking out batteries that meet the requirements of the sales target from the storage facility, it is possible to suppress the situation where there is no vacancy in the storage facility.

[0021] The above and other objects, features, aspects, and advantages of the present invention will become apparent from the following detailed description of the present invention understood in association with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a diagram showing one form of the logistics of the battery pack in the present embodiment.

[0023] Figure 2 is a diagram showing an example of the situation where used batteries are stored in the storage facility.

[0024] Figure 3 is a flowchart showing an outline of the operation process for reusing used batteries.

[0025] Figure 4 is a system configuration diagram showing the electrical structure of a battery cellar.

[0026] [[ID=ic=39]] Figure 5 is a diagram showing an example of the data structure of battery data.

[0027] Figure 6 This is a functional block diagram of a server related to the degradation evaluation of used batteries.

[0028] Figure 7 This is a functional block diagram of a server related to power regulation between battery wells and the power system.

[0029] Figure 8 This is a flowchart illustrating the processing steps for selecting and handling used batteries. Detailed Implementation

[0030] 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.

[0031] 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).

[0032] 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.

[0033] 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.

[0034] 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.

[0035] [Implementation Method]

[0036] <Battery Logistics Model>

[0037] 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 (salesperson) 3, a recycling plant 4, a power system 5, and a distributed energy resource (DER) 6.

[0038] 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 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.

[0039] 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.

[0040] 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).

[0041] Return to Figure 1 Customer 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 sales stores 32 that sell them for use 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).

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Therefore, in this embodiment, the battery well 2 is designed to function not only as a storage location for used batteries 9 but also as a virtual power plant (VPP). This allows the opportunity for the used batteries 9 to be charged and discharged to simultaneously influence the degradation assessment of the used batteries 9, which determines their reuse method, and the power supply and demand balance adjustment 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 power supply and demand balance adjustment based on used batteries 9 are all performed in a "three-in-one" manner within the battery well 2.

[0049] <Reuse Process of Second-hand Batteries>

[0050] 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).

[0051] 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).

[0052] 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).

[0053] 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 used battery 9 used for reassembling the battery pack is basically a used battery 9 whose performance has been restored through the performance restoration process, but it may also include used batteries 9 that have omitted the performance restoration process, and may also include new batteries (new modules). After that, the battery pack is shipped to customer 3 (S6).

[0054] 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.

[0055] 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.

[0056] 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.

[0057] <System Structure of Battery Wells>

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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. Thus, any used battery 9 can be electrically disconnected during the charging and discharging of other used batteries 9, and the used battery 9 can be removed from the storage vault 21.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The battery data storage unit 201 stores battery data in battery well 2 used for managing used batteries 9.

[0066] 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). 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.).

[0067] 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 6 Here is an example illustrating this evaluation method.

[0068] 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 7 Here is an example illustrating this control method.

[0069] 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).

[0070] 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.

[0071] 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.

[0072] <Degradation Assessment>

[0073] Figure 6 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.

[0074] 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, the used battery 9 is charged in order 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 in order 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. Furthermore, increasing DR is equivalent to the "power demand increase request" of this disclosure, and decreasing DR is equivalent to the "power demand decrease request" of this disclosure.

[0075] 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).

[0076] OCV=VB-ΔVp-IB×R…(1)

[0077] 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.

[0078] 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.

[0079] 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.

[0080] C=ΔAh / ΔSOC×100…(2)

[0081] The grading unit 75 grades the used battery 9 according to its full charge capacity C. In this embodiment, as... Figure 2 As shown, reusable used batteries 9 are classified into four grades—S, A, B, and C—in descending order of their full-charge capacity C. On the other hand, used batteries 9 with a full-charge capacity C below a specified value are classified as lower than grade C (recorded as Re) and used for material recycling. Furthermore, the grading unit 75 can record the grading date and time as the deterioration evaluation date and time in the battery data (see reference). Figure 5 ).

[0082] 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 select and retrieve a used battery 9 of the grade that meets the customer 3's requirements from the storage location. By appropriately retrieving used batteries for sale from the storage vault 21, situations where the storage vault 21 is full can be prevented.

[0083] 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. 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.

[0084] <Power Adjustment>

[0085] Figure 7 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] The used battery selection department 84 assesses the rechargeable and discharging electrical capacity of each of the multiple used batteries 9 stored in multiple storage rooms 21 (see reference). Figure 5 (Battery data). The used battery selection unit 84 selects used batteries from a plurality of 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 deficiency of 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 of 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). The used battery selection unit 84 outputs the selected used batteries 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.

[0090] 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.

[0091] 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.

[0092] Furthermore, it is confirmed that, Figure 7 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).

[0093] 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. Therefore, after it is removed from the storage vault 21, there is no need to re-evaluate the degree of degradation of the used batteries 9, thus making efficient use 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 basically performed according to the 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 amount of 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 use it 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. Thus, the storage period of the used batteries 9 can also be used efficiently in terms of money.

[0094] Furthermore, in this embodiment, the used battery 9 is graded based on the results of the degradation evaluation test (full charge capacity). Therefore, when reassembling the used battery 9, the buying and selling price of the used battery 9 can be set in relation to its grade, and the quality of the used battery 9 can be guaranteed according to its grade. Thus, the used battery 9 that has passed through the battery well 2 can be smoothly circulated in the market.

[0095] <Preferred Choice for Used Batteries>

[0096] When the server 20 (used battery selection unit 84) selects a used battery from multiple used batteries 9 for improving or decreasing DR, as explained below, a specific used battery 9 may also be selected preferentially compared to other used batteries.

[0097] Figure 8 This is a flowchart illustrating the processing steps for selecting and handling used battery 9. The flowchart is invoked and executed from the main routine (not shown) when predetermined conditions are met. Each step is implemented through software processing of server 20, but can also be implemented through hardware (circuit) configured within server 20. Hereinafter, the steps will be abbreviated as S.

[0098] In S11, server 20 calculates the battery well adjustment amount in kWh (bat). Regarding the calculation method, in... Figure 7 The details have been explained in detail in the document, so they will not be repeated here.

[0099] In S12, 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 selectable used batteries 9 (in S12, 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 selectable used batteries 9 be charged and discharged. Therefore, server 20 selects all the used batteries 9 (S16).

[0100] On the other hand, if there is a margin relative to the battery well adjustment amount ΔkWh(bat), that is, if the battery well adjustment amount ΔkWh(bat) can be satisfied even without charging and discharging all the selectable used batteries 9 ("Yes" in S12), the server 20 determines whether there are any used batteries 9 among the selectable used batteries 9 that have not undergone degradation evaluation testing or used batteries 9 that have experienced a period longer than the predetermined period since the last degradation evaluation date and time (S13). The server 20 can determine that ungraded used batteries 9 have not undergone degradation evaluation testing. Furthermore, the server 20 can use battery data (see...) Figure 5 Calculate the elapsed time since the last degradation assessment date and time.

[0101] If a used battery 9 that has not undergone a degradation evaluation test exists ("Yes" in S13), the server 20 preferentially selects the used battery 9 that has not undergone a degradation evaluation test (S14). More specifically, the server 20 first selects the used battery 9 that has not undergone a degradation evaluation test, and if the used battery 9 that has not undergone a degradation evaluation test alone cannot meet the battery well adjustment amount ΔkWh (bat), it also selects the used battery 9 that has undergone a degradation evaluation test.

[0102] If there is no used battery 9 for which a degradation evaluation test has not been performed ("No" in S13), the server 20 selects the used battery 9 according to the usual procedures (S15). For example, if the used battery 9 is close to full charge, its degradation is more likely to be accelerated compared to a situation where this is not the case. Furthermore, if the SOC of the used battery 9 is too low, its degradation is also more likely to be accelerated compared to a situation where this is not the case. Therefore, it is possible to select a used battery 9 whose SOC is within a range where degradation is likely to be accelerated, and adjust the charge / discharge rate so that the SOC of the used battery 9 is outside the aforementioned range.

[0103] As mentioned above, in Figure 8 In the example shown, used batteries 9 that have not undergone degradation evaluation testing or used batteries 9 that have been in use for a longer period since the last degradation evaluation date and time are preferentially used for charging and discharging for power adjustment. By preferentially selecting used batteries 9 that have not undergone degradation evaluation testing, it is possible to classify used batteries 9 that have not yet been classified. In addition, battery degradation usually worsens over time. Therefore, for used batteries 9 that have been classified but have been in use for a longer period since the last degradation evaluation date and time, the classification can be updated according to the latest degree of degradation. As a result, the quality management of used batteries 9 in battery well 2 can be improved.

[0104] 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 Control device, The control device controls the power conversion device according to the demand response requirements from the power system, and evaluates the degree of degradation of each of the plurality of batteries based on the voltage and current of each of the batteries charged and discharged by the power conversion device. The power conversion device is configured to perform bidirectional power conversion. The control device, In the case where the demand response request is an increased demand for electricity, the power conversion device is controlled in a manner that allows the plurality of batteries to be charged, and the degree of degradation of the plurality of batteries is evaluated during the charging process. On the other hand... When the demand response request is a request to reduce power demand, the power conversion device is controlled to discharge the plurality of batteries, and the degree of degradation of the plurality of batteries is evaluated during the discharge process. The storage facility includes multiple relays configured to switch the electrical connection and disconnection between each of the multiple batteries and the power conversion device. Upon receiving the demand response request, the control device controls the plurality of relays in such a manner that at least one of the plurality of batteries charged and discharged by the power conversion device includes batteries whose degradation level has not been evaluated and batteries for which a period longer than a predetermined period has elapsed since the last degradation level evaluation.

2. The battery management system according to claim 1, wherein, Upon receiving the demand response request, the control device controls the plurality of relays in a manner that enables the charging and discharging of the number of batteries from the plurality of batteries that meet the demand response request.

3. The battery management system according to claim 1, wherein, The control device classifies each of the multiple batteries according to its degree of degradation.

4. The battery management system according to claim 3, wherein, The battery management system also includes a monitor. The control device selects a battery of a grade that meets the requirements of the sales target from the plurality of batteries stored in the storage room, and notifies the operator of the selected battery using the monitor.

5. The battery management system according to any one of claims 1 to 4, wherein, The control device evaluates the degree of degradation of the plurality of batteries based on their full charge capacity.

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