Energy storage system and control method thereof

Abstract

The invention provides an energy storage system and a control method of the energy storage system, and relates to the technical field of energy storage. The energy storage system comprises at least one energy storage converter, at least two battery stacks and a plurality of buses, each battery stack is connected with the corresponding bus, and each bus is connected with the corresponding energy storage converter; each battery stack comprises a plurality of battery clusters, each battery cluster comprises a high-voltage box and a plurality of battery packs connected in series, and each battery pack comprises at least one battery cell; a first fuse is arranged between each bus and the corresponding energy storage converter, a second fuse is arranged in each high-voltage box, and a third fuse is arranged in each battery pack; and the energy storage converters are used for converting the direct current output by the corresponding cell stacks into alternating current, so that the cell stacks realize electric energy output. When a certain cell stack breaks down, the energy storage converter can control other cell stacks to achieve electric energy output, and therefore the energy storage system can normally achieve electric energy output.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to an energy storage system and a control method for the energy storage system. Background Technology

[0002] With the rapid development of energy storage technology, energy storage systems have become one of the most widely used energy storage technologies due to their advantages such as flexible installation and short construction period.

[0003] In existing energy storage systems, a single battery stack is typically used to output power. If this single battery stack fails, the entire energy storage system will be unable to output power. Summary of the Invention

[0004] In view of this, embodiments of this application provide an energy storage system and a control method for the energy storage system, which allows the energy storage converter to control other battery stacks to output electrical energy when a battery stack fails, so that the energy storage system can output electrical energy normally.

[0005] A first aspect provides an energy storage system, comprising: at least one energy storage converter, at least two battery stacks, and multiple buses, each battery stack being connected to a corresponding bus, and each bus being connected to a corresponding energy storage converter; each battery stack comprising multiple battery clusters, each battery cluster comprising a high-voltage box and multiple battery packs connected in series, each battery pack comprising at least one battery cell; a first fuse is provided between each bus and the corresponding energy storage converter, a second fuse is provided in each high-voltage box, and a third fuse is provided in each battery pack; the energy storage system further comprises a BCU located in each high-voltage box; The energy storage converter is used to convert the DC power output from the corresponding battery stack into AC power so that the battery stack can output electrical energy. The first fuse is used to blow when the circuit between the busbar and the energy storage converter is short-circuited; the second fuse is used to blow when the circuit inside the high-voltage box is short-circuited; and the third fuse is used to blow when the circuit inside the battery pack is short-circuited. The BCU is used to control the state of the battery cell.

[0006] In one possible implementation, the number of energy storage converters is one; The energy storage converter is specifically used to convert the direct current output from each of the battery stacks into alternating current.

[0007] In one possible implementation, there are two battery stacks, two energy storage converters, and two buses. The two battery stacks include a first battery stack and a second battery stack. The two energy storage converters include a first energy storage converter and a second energy storage converter. The two buses include a first bus and a second bus. The first battery stack is connected to the corresponding first energy storage converter via the first bus. The second battery stack is connected to the corresponding second energy storage converter via the second bus. The first energy storage converter is used to convert the DC power output from the corresponding first battery stack into AC power so that the first battery stack can output electrical energy. The second energy storage converter is used to convert the DC power output from the corresponding second battery stack into AC power, so that the second battery stack can output electrical energy.

[0008] In one possible implementation, the high-voltage box includes a control circuit, one end of which is connected to a corresponding busbar, and the other end of which is connected to one end of a plurality of battery packs connected in series; the control circuit includes a circuit breaker, a first contactor, and a second fuse connected in series. The BCU is used to first control the circuit breaker to open, and then control the first contactor to open.

[0009] In one possible implementation, the BCU is specifically used to calculate the first parameter of the battery cell using the ampere-hour integration method to generate the first SOC of the battery cell at multiple times; within a first set time period, if it is determined that the state parameter of the battery cell at any time among the multiple times satisfies any calibration condition, the first SOC at the current time is calibrated according to the calibration rule corresponding to the satisfied calibration condition to generate the calibrated SOC.

[0010] In one possible implementation, the BCU is specifically used to generate the cumulative ampere-hour throughput of the battery cell at the current moment based on the ampere-hour throughput at multiple moments of the acquired battery cell; to query a first capacity decay value corresponding to the cumulative ampere-hour throughput at the current moment through a set cyclic aging curve of the battery cell; to query a second capacity decay value corresponding to the current moment through a set calendar aging curve of the battery cell; and to generate the first state of equilibrium (SOH) of the battery cell at the current moment based on the first capacity decay value and the second capacity decay value.

[0011] A second aspect provides a control method for an energy storage system, the energy storage system comprising: at least one energy storage converter, at least two battery stacks and multiple buses, each battery stack being connected to a corresponding bus, and each bus being connected to a corresponding energy storage converter; each battery stack comprising multiple battery clusters, each battery cluster comprising a high-voltage box and multiple battery packs connected in series, each battery pack comprising at least one battery cell; a first fuse is provided between each bus and the corresponding energy storage converter, a second fuse is provided in each high-voltage box, and a third fuse is provided in each battery pack; the energy storage system further comprises a BCU located in each high-voltage box; The control method for the energy storage system includes: The energy storage converter converts the DC power output from the corresponding battery stack into AC power, so that the battery stack can output electrical energy. The first fuse blows when the circuit between the busbar and the energy storage converter is short-circuited; the second fuse blows when the circuit inside the high-voltage box is short-circuited; and the third fuse blows when the circuit inside the battery pack is short-circuited. The BCU controls the state of the battery cell.

[0012] In one possible implementation, the BCU controls the state of the battery cell, including: The BCU calculates the first parameters of the battery cell using the ampere-hour integration method to generate the first SOC of the battery cell at multiple times. If the BCU determines that the state parameter of the battery cell at any time within a first set time period meets any calibration condition, it calibrates the first SOC at the current time according to the calibration rule corresponding to the met calibration condition, and generates the calibrated SOC.

[0013] In one possible implementation, the BCU controls the state of the battery cell, including: If the BCU determines that the state parameters of the battery cell at multiple times do not meet any calibration conditions within a first set time period, it uses the generated second SOC of the battery cell at the current time to calibrate the first SOC at the current time and generates a calibrated SOC. The second SOC of the battery cell at the current moment is generated by the BCU through the EKF algorithm based on the second-order RC circuit to calculate the second parameters of the battery cell.

[0014] In one possible implementation, after generating the calibrated SOC, the method further includes: The BCU resets the first set time period and continues to execute the step of calculating the first parameters of the battery cell using the ampere-hour integration method to generate the first SOC of the battery cell at multiple times.

[0015] In one possible implementation, if the state parameter includes current; the BCU, within a first set time period, determines that the state parameter of the battery cell at any time among multiple times satisfies any calibration condition, calibrates the first SOC at the current time according to the calibration rule corresponding to the satisfied calibration condition, generating a calibrated SOC, including: If the BCU determines that the absolute value of the current is less than a set current threshold, and the duration for which the absolute value of the current is less than the set current threshold reaches a set duration, it obtains the current voltage and current temperature of the battery cell from the BMU, queries the OCV-SOC curve corresponding to the current temperature from the correspondence between the battery cell temperature and the OCV-SOC curve, queries the SOC corresponding to the current voltage of the battery cell through the OCV-SOC curve corresponding to the current temperature, and uses the SOC corresponding to the current voltage of the battery cell as the reference SOC. The BCU adjusts the first SOC at the current moment to the reference SOC, so that the calibrated SOC becomes the reference SOC.

[0016] In one possible implementation, if the state parameters include voltage and current; the BCU, within a first set time period, determines that the state parameters of the battery cell at any of the multiple moments satisfy any calibration condition, calibrates the first SOC at the current moment according to the calibration rule corresponding to the satisfied calibration condition, generating a calibrated SOC, including: If the BCU determines that the current voltage of the battery cell has reached the charging cutoff voltage and the current current of the battery cell has dropped to the cutoff current, it resets the first SOC at the current moment to 100% so that the calibrated SOC is 100%.

[0017] In one possible implementation, if the state parameter includes voltage; the BCU, within a first set time period, determines that the state parameter of the battery cell at any of the multiple times satisfies any calibration condition, calibrates the first SOC at the current time according to the calibration rule corresponding to the satisfied calibration condition, generating a calibrated SOC, including: If the BCU determines that the current voltage of the battery cell has reached the discharge cutoff voltage, it resets the first SOC at the current moment to 0% so that the calibrated SOC is 0%.

[0018] In one possible implementation, the step of calibrating the first SOC at the current moment using the generated second SOC of the battery cell to generate a calibrated SOC includes: The BCU adds the product of the first SOC at the current time and the corresponding first scaling factor to the product of the second SOC at the current time and the corresponding second scaling factor to generate the calibrated SOC.

[0019] In one possible implementation, the BCU controls the state of the battery cell, including: The BCU generates the cumulative ampere-hour throughput of the battery cell at the current moment based on the ampere-hour throughput at multiple moments of the acquired battery cell. The BCU uses the set cyclic aging curve of the battery cell to query the first capacity decay value corresponding to the cumulative ampere-hour throughput at the current moment. The BCU uses the set calendar aging curve of the battery cell to query the second capacity decay value corresponding to the current moment. The BCU generates the first SOH of the battery cell at the current moment based on the first capacity decay value and the second capacity decay value.

[0020] In one possible implementation, the BCU generates the cumulative ampere-hour throughput of the battery cell at the current moment based on the acquired ampere-hour throughput at multiple moments of the battery cell, including: The BCU multiplies the ampere-hour throughput of the battery cell at multiple moments by the corresponding temperature coefficient to obtain the multiplication result, and adds the multiplication results of multiple moments to generate the cumulative ampere-hour throughput of the battery cell at the current moment.

[0021] In one possible implementation, the BCU generates the first SOH of the battery cell at the current moment based on the first capacity decay value and the second capacity decay value, including: The BCU subtracts the first capacity decay value and the second capacity decay value from 100% to generate the first SOH at the current moment.

[0022] In one possible implementation, the BCU controls the state of the battery cell, including: The BCU calculates the second SOH of the battery cell at the current moment using a real-time capacity estimation method. The BCU calibrates the first SOH of the battery cell at the current moment using the second SOH of the battery cell at the current moment, and generates the calibrated SOH at the current moment.

[0023] In one possible implementation, the BCU calculates the second SOH of the battery cell at the current moment using a real-time capacity estimation method, including: When the battery cell is in a charging state, the BCU records the first cumulative charge amount corresponding to the initial SOC and the second cumulative charge amount corresponding to the full charge SOC, wherein the initial SOC is less than or equal to a set SOC threshold. The BCU subtracts the first cumulative charge amount from the second cumulative charge amount to generate the actual charge amount; The BCU multiplies the difference between the full charge SOC and the initial SOC by the capacity of the battery cell to generate the theoretical charging amount. The BCU divides the actual charge amount by the theoretical charge amount to generate the second SOH of the battery cell at the current moment.

[0024] In one possible implementation, the BCU calibrates the first SOH of the battery cell at the current moment using the second SOH of the battery cell at the current moment, and after generating the calibrated SOH at the current moment, it further includes: The BCU calculates the SOH difference between the first SOH at the current time and the first SOH at any time after the current time; The BCU subtracts the SOH difference from the calibrated SOH at the current time to generate the calibrated SOH at any time after the current time.

[0025] The beneficial effects of this application are as follows: In the technical solution provided in this application embodiment, the energy storage converter can convert the DC power output of the corresponding battery stack into AC power so that the battery stack can output electrical energy. When a battery stack fails, the energy storage converter can control other battery stacks to output electrical energy, thereby enabling the energy storage system to output electrical energy normally. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application; Figure 2 This is a schematic diagram of another energy storage system provided in an embodiment of this application; Figure 3 A schematic diagram of the communication architecture of the energy storage system provided in the embodiments of this application; Figure 4 A flowchart illustrating a method for generating a SOC as provided in an embodiment of this application; Figure 5 A flowchart illustrating a method for generating a second SOC as provided in an embodiment of this application; Figure 6 A flowchart illustrating a method for generating a first SOH provided in an embodiment of this application; Figure 7 A flowchart illustrating a method for generating a second SOH provided in an embodiment of this application.

[0028] Figure label: 11-First battery stack; 12-Second battery stack; 13-First PCS; 14-Second PCS; 15-First busbar; 16-Second busbar; 18-PCS; 71-High voltage box; 72-Battery pack; 73-Hall sensor. Detailed Implementation

[0029] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0030] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0031] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0033] Figure 1 This is a schematic diagram of the structure of an energy storage system provided in an embodiment of this application, as shown below. Figure 1As shown, the energy storage system may include: at least one power conversion system (PCS), at least two battery stacks and multiple buses, each battery stack being connected to a corresponding bus, and each bus being connected to a corresponding power conversion system; each battery stack includes multiple battery clusters, each battery cluster including a high-voltage box and multiple battery packs connected in series, each battery pack including at least one battery cell; a first fuse is provided between each bus and the corresponding power conversion system, a second fuse is provided in each high-voltage box, and a third fuse is provided in each battery pack.

[0034] In this embodiment, the PCS can be used to convert the direct current (DC) output from the corresponding battery stack into alternating current (AC), enabling the battery stack to output electrical energy. The number of PCS can be one or more, and each PCS can control one or more battery stacks; that is, each PCS can convert the DC output from one or more battery stacks into AC. Alternatively, if there is only one PCS, it can correspond to multiple battery stacks, and thus control multiple battery stacks, converting the DC output from each battery stack into AC. Another alternative is that if there are multiple PCS, each PCS can correspond to one battery stack, and thus control the corresponding battery stack, converting the DC output from the corresponding battery stack into AC.

[0035] As an optional configuration, the battery stacks consist of two units, the PCS consists of two units, and the buses consist of two buses. The two battery stacks may include a first battery stack 11 and a second battery stack 12. The two PCS may include a first PCS 13 and a second PCS 14. The two buses may include a first bus 15 and a second bus 16. The first battery stack 11 is connected to the corresponding first PCS 13 via the first bus 15; the second battery stack 12 is connected to the corresponding second PCS 14 via the second bus 16. The first PCS 13 converts the direct current output from the first battery stack 11 into alternating current, enabling the first battery stack 11 to output electrical energy. The second PCS 14 converts the direct current output from the second battery stack 12 into alternating current, enabling the second battery stack 12 to output electrical energy.

[0036] like Figure 1 As shown, the first battery stack 11 may include multiple battery clusters, and the second battery stack 12 may include multiple battery clusters. For example, the first battery stack 11 may include four battery clusters, which may include battery clusters 1 to 4; the second battery stack 12 may include four battery clusters, which may include battery clusters 5 to 8. In practical applications, the number of battery clusters included in each battery stack can be set as needed, and this embodiment does not limit this.

[0037] like Figure 1 As shown, the description takes battery cluster 1 in the first battery stack 11 as an example. Battery cluster 1 may include a high-voltage box 71 and multiple battery packs 72 connected in series, with the multiple battery packs 72 connected in series to the high-voltage box 71. The high-voltage box 71 includes a control circuit, one end of which is connected to the corresponding first busbar 15, and the other end of which is connected to one end of the multiple battery packs 72 connected in series. The control circuit may include a circuit breaker QF, a first contactor KM1, and a second fuse FU2 connected in series, and may also include a resistor R and a second contactor KM2. The circuit breaker QF, the first contactor KM1, and the second fuse FU2 are connected in series between the first busbar 15 and the battery packs 72, and the resistor R and the second contactor KM2 are connected in parallel with the first contactor KM1. Specifically, the first terminal of circuit breaker QF is connected to the first busbar 15, the second terminal of circuit breaker QF is connected to the first terminal of first contactor KM1, the second terminal of first contactor KM1 is connected to the first terminal of second fuse FU2, and the second terminal of second fuse FU2 is connected to battery pack 72; the first terminal of resistor R is connected to the second terminal of circuit breaker QF and the first terminal of first contactor KM1, the second terminal of resistor R is connected to the first terminal of second contactor KM2, and the second terminal of second contactor KM2 is connected to the second terminal of first contactor KM1 and the first terminal of second fuse FU2.

[0038] like Figure 1 As shown, each battery pack 72 includes at least one battery cell, and each battery pack 72 is provided with a third fuse FU3.

[0039] In this embodiment, the structure of the remaining battery clusters in the first battery stack 11 and the second battery stack 12 can be the same as the structure of the battery cluster 1 described above, and will not be repeated here.

[0040] like Figure 1 As shown, a first fuse FU1 is provided between the first busbar 15 and the corresponding first PCS 13. Specifically, the first end of the first fuse FU1 is connected to the first PCS 13, and the second end of the first fuse FU1 is connected to the first busbar 15.

[0041] like Figure 1 As shown, a first fuse FU1 is provided between the second busbar 16 and the corresponding second PCS 14. Specifically, the first end of the first fuse FU1 is connected to the second PCS 14, and the second end of the first fuse FU1 is connected to the second busbar 16.

[0042] As an alternative, the energy storage system may also include a surge protector corresponding to each battery stack and a fourth fuse corresponding to each surge protector. Each surge protector can be connected to the corresponding PCS through the corresponding fourth fuse.

[0043] like Figure 1 As shown, there can be two surge protectors and two fourth fuses FU4. The two surge protectors can include a first surge protector SPD1 corresponding to the first battery stack 11 and a second surge protector SPD2 corresponding to the second battery stack 12. The first end of the first surge protector SPD1 is connected to the second end of the corresponding fourth fuse FU4, and the second end of the first surge protector SPD1 is grounded. The first end of the fourth fuse FU4 is connected to the first PCS 13 and the first end of the corresponding first fuse FU1. The first end of the second surge protector SPD2 is connected to the second end of the corresponding fourth fuse FU4, and the second end of the second surge protector SPD2 is grounded. The first end of the fourth fuse FU4 is connected to the second PCS 14 and the first end of the corresponding first fuse FU1.

[0044] In this embodiment of the application, the PCS is used to convert the direct current output from the corresponding battery stack into alternating current, so that the battery stack can output electrical energy. For example... Figure 1 As shown, the first PCS 13 is used to convert the DC power output by the corresponding first battery stack 11 into AC power so that the first battery stack 11 can output electrical energy; the second PCS 14 is used to convert the DC power output by the corresponding second battery stack 12 into AC power so that the second battery stack 12 can output electrical energy.

[0045] If the first battery stack 11 fails, but the second battery stack 12 is operating normally, the second PCS 14 can independently control the second battery stack 12 to output power, thus enabling the energy storage system to output power normally. If the second battery stack 12 fails, but the first battery stack 11 is operating normally, the first PCS 13 can independently control the first battery stack 11 to output power, thus enabling the energy storage system to output power normally. If both the first battery stack 11 and the second battery stack 12 are operating normally, the first PCS 13 can independently control the first battery stack 11 to output power, and the second PCS 14 can independently control the second battery stack 12 to output power, thus enabling the energy storage system to output power normally.

[0046] In this embodiment of the application, the first battery stack 11 is independently controlled by the first PCS 13 and the second battery stack 12 is independently controlled by the second PCS 14, thereby enabling the two battery stacks to output electrical energy independently.

[0047] In this embodiment, the first PCS controls the first battery stack to achieve power output, and the second PCS controls the second battery stack to achieve power output. When the battery stack controlled by one PCS fails, the other PCS can control the other battery stack to achieve power output, thereby enabling the energy storage system to achieve normal power output.

[0048] In this embodiment, the first fuse FU1 can be used to blow when the circuit between the busbar and the PCS is short-circuited, the second fuse FU2 can be used to blow when the circuit in the high-voltage box 71 is short-circuited, and the third fuse FU3 can be used to blow when the circuit in the battery pack 72 is short-circuited.

[0049] like Figure 1 As shown, when a short circuit occurs between the first busbar 15 and the first PCS 13, the first fuse FU1 blows, thereby protecting the circuit between the first busbar 15 and the first PCS 13; when a short circuit occurs between the second busbar 16 and the second PCS 14, the first fuse FU1 blows, thereby protecting the circuit between the second busbar 16 and the second PCS 14.

[0050] like Figure 1 As shown, when the circuit inside the high-voltage box 71 is short-circuited, the second fuse FU2 blows, thereby protecting the circuit inside the high-voltage box 71.

[0051] like Figure 1 As shown, when the circuit inside the battery pack 72 is short-circuited, the third fuse FU3 blows, thereby protecting the circuit inside the battery pack 72.

[0052] In this embodiment, by setting a first fuse, a second fuse, and a third fuse, the energy storage system achieves a three-level fuse circuit, thereby protecting the energy storage system circuit.

[0053] Figure 2 This is a schematic diagram of another energy storage system provided in an embodiment of this application, as shown below. Figure 2 As shown, this embodiment is similar to Figure 1 The difference in the illustrated embodiment is that the number of PCS is one. The energy storage system includes PCS 18, with a first battery stack 11 connected to the corresponding PCS 18 via a first bus 15, and a second battery stack 12 connected to the corresponding PCS 18 via a second bus 16. PCS 18 can be used to individually convert the DC power output from each battery stack into AC power. Specifically, PCS 18 can convert the DC power output from the first battery stack 11 into AC power to enable the first battery stack 11 to output electrical energy; PCS 18 can also convert the DC power output from the second battery stack 12 into AC power to enable the second battery stack 12 to output electrical energy.

[0054] If the first battery stack 11 fails and the second battery stack 12 is operating normally, the PCS 18 can independently control the second battery stack 12 to output power, thus enabling the energy storage system to output power normally. If the second battery stack 12 fails and the first battery stack 11 is operating normally, the PCS 18 can independently control the first battery stack 11 to output power, thus enabling the energy storage system to output power normally. If both the first battery stack 11 and the second battery stack 12 are operating normally, the PCS 18 simultaneously controls both the first battery stack 11 and the second battery stack 12 to output power, thus enabling the energy storage system to output power normally.

[0055] When PCS 18 simultaneously controls the first battery stack 11 and the second battery stack 12 to achieve power output, the power of PCS 18 is the first power; when PCS 18 controls the first battery stack 11 or the second battery stack 12 alone, the power of PCS 18 is the second power. The first power can be twice the second power.

[0056] In this embodiment of the application, when one PCS controls at least two battery stacks, if one of the battery stacks controlled by the PCS fails, the PCS can still control the other battery stacks to output power, thereby enabling the energy storage system to output power normally.

[0057] like Figure 2 As shown, a first fuse FU1 is provided between the first busbar 15 and the PCS 18. Specifically, the first end of the first fuse FU1 is connected to the PCS 18, and the second end of the first fuse FU1 is connected to the first busbar 15.

[0058] like Figure 2 As shown, a first fuse FU1 is provided between the second busbar 16 and the PCS 18. Specifically, the first end of the first fuse FU1 is connected to the PCS 18, and the second end of the first fuse FU1 is connected to the second busbar 16.

[0059] like Figure 2 As shown, the first terminal of the first surge protector SPD1 is connected to the second terminal of the corresponding fourth fuse FU4, the second terminal of the first surge protector SPD1 is grounded, and the first terminal of the fourth fuse FU4 is connected to PCS 18 and the first terminal of the corresponding first fuse FU1; the first terminal of the second surge protector SPD2 is connected to the second terminal of the corresponding fourth fuse FU4, the second terminal of the second surge protector SPD2 is grounded, and the first terminal of the fourth fuse FU4 is connected to PCS 18 and the first terminal of the corresponding first fuse FU1.

[0060] In this embodiment of the application, for Figure 2 For further description of the medium-energy storage system, please refer to Figure 1The description of the illustrated embodiment will not be repeated here.

[0061] Figure 3 A schematic diagram of the communication architecture of the energy storage system provided in the embodiments of this application is shown below. Figure 3 As shown, the energy storage system also includes a System Control Unit (SCU), a Battery Cluster Management Unit (BCU), and a Battery Management Unit (BMU). The SCU, BCU, and BMU implement a three-tier architecture for the energy storage system's Battery Management System (BMS), where the first-tier BMS is the BMU, the second-tier BMS is the BCU, and the third-tier BMS is the SCU.

[0062] like Figure 3 As shown, within any given battery cluster, each battery pack is equipped with a corresponding BMU, and each high-voltage box 71 is equipped with a BCU. Each BMU is communicatively connected to its corresponding BCU. Each BCU is communicatively connected to the SCU. The SCU is also connected to the PCS.

[0063] The high-voltage box 71 is also equipped with at least one current sensor, for example, a Hall sensor 73. In this embodiment, the high-voltage box 71 is equipped with at least one Hall sensor 73 as an optional solution, such as... Figure 3 As shown, two Hall sensors 73 can be installed inside the high-voltage box 71. Each Hall sensor 73 is connected to the BCU, and the Hall sensor 73 is also connected to the second fuse FU2 and the battery pack 72.

[0064] In this embodiment, two Hall sensors 73 are installed inside the high-voltage box 71. When one Hall sensor fails, the other Hall sensor can be used to collect the current, preventing the failure of a single Hall sensor from causing the inability to collect the current, thereby improving the reliability of the current collection.

[0065] like Figure 3 As shown, the BCU is also connected to the circuit breaker QF and the first contactor KM1.

[0066] Figure 3 This example uses PCS 18 as an example. In practical applications, other methods can also be used. Figure 1 For a detailed description of the structure of the first PCS13 and the second PCS14, please refer to [link / reference needed]. Figure 1 The description in the text will not be repeated here. It should be noted that: Figure 3 for Figure 2 The corresponding communication architecture of the energy storage system, Figure 3Only shown in Figure 2 The middle part of the electronic components.

[0067] like Figure 3 As shown, the BMU can adopt active balancing, is compatible with passive balancing design, and uses a high-performance analog front end (AFE) to improve the acquisition accuracy of data such as voltage and temperature; the BCU can be used to control the state of the battery cells, such as the state of charge (SOC), state of health (SOH), and state of energy (SOE). The BCU can also perform thermal runaway early warning and battery fault diagnosis; the SCU has a multi-data type interface, which can input and output various types of data to communicate with external devices, form control and acquisition of external data, and can adjust the energy storage system according to the external devices.

[0068] like Figures 1 to 3 As shown, a circuit breaker QF and a first contactor KM1 are formed on the branch circuit inside the high-voltage box 71. When the DC side fault current is too high, the BCU needs to disconnect the circuit breaker QF and the first contactor KM1 on the branch circuit. The disconnection control can be performed according to a pre-set disconnection sequence. As an optional scheme, the BCU first controls the circuit breaker QF to disconnect, and then controls the first contactor KM1 to disconnect. When the DC side fault current is too high, the BCU controls the circuit breaker QF and the first contactor KM1 to disconnect, thereby achieving circuit protection. Since the electrical life of the first contactor KM1 is limited, disconnecting the circuit breaker QF first ensures that there is no current in the branch circuit. Then, disconnecting the first contactor KM1 allows it to disconnect without load, thus extending the life of the first contactor KM1.

[0069] Based on the above Figures 1 to 3 The energy storage system shown in this application provides a control method for the energy storage system. This method may include: the PCS converting the DC power output from the corresponding battery stack into AC power to enable the battery stack to output electrical energy; a first fuse blowing when there is a short circuit between the bus and the energy storage converter, a second fuse blowing when there is a short circuit in the high-voltage box, and a third fuse blowing when there is a short circuit in the battery pack; and the BCU controlling the state of the battery cells.

[0070] In this embodiment of the application, the state of the battery cell may include SOC or SOH. The BCU can control the SOC of the battery cell, or the BCU can control the SOH of the battery cell.

[0071] Figure 4 A flowchart illustrating a method for generating a SOC as provided in this application embodiment is shown below. Figure 4As shown, the method includes: Step 102: The BCU calculates the first parameters of the cell using the ampere-hour integration method, generating the first SOC of the cell at multiple times.

[0072] As an optional approach, the first parameters of the battery cell may include the cell's initial state of charge (SOC), rated capacitance, and current. A positive current indicates a charging current; a negative current indicates a discharging current. A current sensor within the high-voltage box collects the current of the battery cluster, which in turn determines the current of the individual battery cells. The current sensor then transmits this current reading to the battery control unit (BCU). Figure 3 As shown, the current sensor includes a Hall sensor 73.

[0073] For example, BCU can be expressed by the formula: Calculate the first state of charge (SOC) of the battery cell at the current moment. In the above formula, The first SOC at time t, Initial time SOC, This refers to the rated capacity of the battery cell. For Coulomb efficiency, This represents the current of the battery cell at the current moment. Specifically, when the battery cell is discharging... When the battery cell is charging, .

[0074] In this embodiment, by collecting the current at different times of different cells, the first SOC of the cell at different times can be calculated by the ampere-hour integration method. The calculation method is simple and easy to implement, and the SOC calculation can be realized continuously during the charging and discharging process of the cell.

[0075] As an alternative, the method may further include: the BCU sending the first SOC to the SCU so that the SCU can display the first SOC.

[0076] However, the use of the ampere-hour integration method for SOC calculation has the following problems: the ampere-hour integration method depends on the initial time. of ,like Inaccuracy will cause all subsequent calculations to accumulate errors; the accuracy, sampling frequency, and noise of the current sensor will cause the integration error to increase continuously over time; coulomb efficiency... It is not fixed and is affected by temperature, SOC, and current magnitude. In summary, the aforementioned issues can lead to inaccuracies in the first SOC calculated using the ampere-hour integration method.

[0077] To resolve the issue of inaccurate first SOC, it can be calibrated using the methods described in the following steps.

[0078] Step 104: Within the first set time period, the BCU determines whether the state parameters of the battery cell at any time among multiple times meet any calibration condition. If yes, proceed to step 106; otherwise, proceed to step 108.

[0079] In this embodiment of the application, if the BCU determines that the state parameters of the battery cell at any time within a first set time period meet any calibration condition, it executes step 106; if the BCU determines that the state parameters of the battery cell at any time within a first set time period do not meet any calibration condition, it executes step 108.

[0080] As an optional approach, the BCU assesses the state parameters at multiple points within the first time period. When the state parameters at a given point satisfy any calibration condition, step 106 is executed for the first SOC at that point. This point can be considered the current point. In other words, the moment when the state parameters satisfy any calibration condition can be understood as the current point. Therefore, the current point in step 106 below can be understood as any point when the state parameters satisfy any calibration condition.

[0081] Step 106: The BCU calibrates the first SOC at the current moment according to the calibration rules corresponding to the calibration conditions met, and generates the calibrated SOC.

[0082] The BCU calculates the first SOC at different times through step 102, and then calibrates the first SOC within a first set time period. The first set time period can be set according to actual needs; for example, the first set time period can be one day or two days.

[0083] As an optional approach, the status parameter may include the absolute value of the current, and the calibration condition may include the absolute value of the current being less than a set current threshold and the duration for which the absolute value of the current is less than the set current threshold reaches a set duration. The calibration rule corresponding to the calibration condition is open circuit voltage (OCV) calibration.

[0084] In this approach, step 106 may specifically include: Step 1062: If the BCU determines that the absolute value of the current is less than the set current threshold and the duration of the absolute value of the current being less than the set current threshold reaches the set duration, it obtains the current voltage and current temperature of the cell from the BMU, queries the correspondence between the cell temperature and the OCV-SOC curve to find the OCV-SOC curve corresponding to the current temperature, queries the SOC corresponding to the current voltage of the cell through the OCV-SOC curve corresponding to the current temperature, and uses the SOC corresponding to the current voltage of the cell as the reference SOC.

[0085] As an optional approach, each cell model has a corresponding relationship between temperature and OCV-SOC curve. That is, the cell model corresponds to the temperature and OCV-SOC curve of that cell. Therefore, the temperature and OCV-SOC curve corresponding to the cell model can be obtained through the cell model. The temperature and OCV-SOC curve corresponding to the cell model is the temperature and OCV-SOC curve of that cell.

[0086] For each battery cell, different temperatures correspond to different OCV-SOC curves. Therefore, the correspondence between temperature and OCV-SOC curves can include multiple temperatures and the corresponding OCV-SOC curve for each temperature. The BCU can then use this correspondence to find the OCV-SOC curve corresponding to the current temperature.

[0087] As an alternative approach, if the temperature at the current moment is not found in the correspondence between temperature and OCV-SOC curves, a first temperature can be determined from among multiple temperatures in the correspondence, where the absolute value of the difference between the first temperature and the current temperature is the smallest. The OCV-SOC curve corresponding to the first temperature is then retrieved from the correspondence. This OCV-SOC curve is then used as the OCV-SOC curve corresponding to the current temperature. If there are two possible first temperatures, one can be arbitrarily selected. The OCV-SOC curve corresponding to this arbitrarily selected first temperature is then retrieved from the correspondence, and this arbitrarily selected OCV-SOC curve is used as the OCV-SOC curve corresponding to the current temperature. When the BCU determines that the absolute value of the current is less than the set current threshold and the duration of this condition reaches the set duration, it indicates that the cell has been resting for a sufficiently long period and the voltage has stabilized. At this point, performing OCV calibration using the voltage and OCV-SOC curve will not introduce new errors. The BMU can read the current voltage of the cell and send it to the BCU; this current voltage is the cell's static voltage. Both the set current threshold and the set duration can be configured as needed; for example, the set current threshold could be 0.5A and the set duration could be 1 hour.

[0088] The BCU pre-stores the OCV-SOC curve of the battery cell and queries the SOC corresponding to the current voltage of the battery cell using the pre-stored OCV-SOC curve. The SOC corresponding to the current voltage of the battery cell can be used as a reference SOC for calibration.

[0089] Step 1064: The BCU adjusts the first SOC at the current moment to the reference SOC so that the calibrated SOC is the reference SOC.

[0090] For example, if the baseline SOC is 25% and the first SOC is 30%, the BCU can adjust the first SOC to 25% so that the calibrated SOC is 25%.

[0091] In this embodiment, if the BCU determines that the absolute value of the current is less than a set current threshold and the duration of the absolute value of the current being less than the set current threshold reaches a set duration, it achieves the calibration of the first SOC when the cell is in a static state through OCV calibration, thereby reducing the error of the SOC calculated by the ampere-hour integration method and improving the accuracy of the SOC.

[0092] As an alternative, the status parameters can include voltage and current. The calibration conditions include the cell voltage reaching the charging cutoff voltage and the cell current dropping to the cutoff current. In this case, the calibration rule is full charge calibration.

[0093] In this scheme, if the BCU determines that the current voltage of the battery cell has reached the charging cutoff voltage and the current current of the battery cell has dropped to the cutoff current, it will reset the first SOC of the current moment to 100% so that the calibrated SOC is 100%. The BMU can collect the current voltage and send the current current to the BCU.

[0094] During the charging process of the battery cell, if the BCU determines that the current voltage of the battery cell has reached the charging cutoff voltage and the current current of the battery cell has dropped to the cutoff current, it indicates that the battery cell has reached the full charge state, that is, the constant voltage (CV) stage has ended. At this time, the BCU can reset the first SOC to 100% so that the calibrated SOC is 100%.

[0095] In this embodiment, if the BCU determines that the current voltage of the battery cell reaches the charging cutoff voltage and the current current of the battery cell drops to the cutoff current, it achieves the calibration of the first SOC when the battery cell is in the charging state through full charge calibration, thereby reducing the error of the SOC calculated by the ampere-hour integration method and improving the accuracy of the SOC.

[0096] As another alternative, the status parameter may include voltage, and the calibration condition may include the current voltage of the cell reaching the discharge cutoff voltage, in which case the calibration rule is full discharge calibration.

[0097] In this scheme, during the cell discharge process, if the BCU determines that the current voltage of the cell has reached the discharge cutoff voltage, it will reset the first SOC at the current moment to 0% so that the calibrated SOC is 0%.

[0098] In this embodiment, if the BCU determines that the current voltage of the battery cell has reached the discharge cutoff voltage, it performs full discharge calibration to calibrate the first SOC when the battery cell is in the discharge state, thereby reducing the error of the SOC calculated by the ampere-hour integration method and improving the accuracy of the SOC.

[0099] In this embodiment of the application, if the BCU determines that the state parameter of the battery cell at any moment meets any of the above calibration conditions within the first set time period, it can calibrate the first SOC by means of the calibration rule corresponding to the met calibration conditions, thereby reducing the error of the SOC calculated by the ampere-hour integration method and improving the accuracy of the SOC.

[0100] As an optional approach, step 106 may further include: the BCU sending the calibrated SOC to the SCU so that the SCU can display the calibrated SOC.

[0101] As an optional approach, step 106 may also include: the BCU resetting the first set time period and continuing to execute step 102.

[0102] In this embodiment, after the BCU calibrates the first SOC at any time within the first set time period, the first set time period can be reset, that is, the timing of the first set time period can be restarted. This scheme allows the BCU to continue calibrating the first SOC calculated by the ampere-hour integration method, thereby realizing real-time calibration of the first SOC.

[0103] Step 108: The BCU uses the second SOC of the cell at the current moment to calibrate the first SOC at the current moment and generate the calibrated SOC.

[0104] Specifically, the BCU can use an Extended Kalman Filter (EKF) algorithm based on a second-order RC circuit to calculate the second parameters of the battery cell and generate the second SOC of the battery cell at multiple times. The second SOC of the battery cell at multiple times includes the second SOC at the current time.

[0105] In this embodiment, the state parameter may include the absolute value of the current, and the calibration condition may include the absolute value of the current being less than a set current threshold and the duration for which the absolute value of the current is less than the set current threshold reaching a set duration; or, the state parameter may include voltage and current, and the calibration condition may include the cell voltage reaching the charging cutoff voltage and the cell current dropping to the cutoff current; or, the state parameter may include voltage, and the calibration condition may include the cell voltage at the current moment reaching the discharging cutoff voltage.

[0106] If, within a first predetermined time period, the BCU determines that the state parameters of the battery cell at multiple moments do not meet any of the aforementioned calibration conditions, then after the first predetermined time period ends, it uses the second SOC of the battery cell at the current moment to calibrate the first SOC at the current moment, generating a calibrated SOC. Here, the current moment can be understood as the moment following the end of the first predetermined time period.

[0107] In this embodiment of the application, if the BCU determines that the state parameters of the battery cell at multiple times do not meet any of the above calibration conditions within the first set time period, it can use the second SOC calculated by the EKF algorithm based on the second-order RC circuit to calibrate the first SOC calculated by the ampere-hour integration method, thereby reducing the error of the SOC calculated by the ampere-hour integration method and improving the accuracy of the SOC.

[0108] In this embodiment of the application, step 108 may include: the BCU adding the product of the first SOC at the current time and the corresponding first scaling factor to the product of the second SOC at the current time and the corresponding second scaling factor to generate the calibrated SOC.

[0109] The BCU adds the products of the first SOC and the second SOC to their respective proportional coefficients, so that the calibration process takes into account both the SOC calculated by the ampere-hour integration method and the SOC calculated by the EKF algorithm based on the second-order RC circuit, thereby further improving the accuracy of the SOC.

[0110] As an optional approach, the sum of the first proportional coefficient and the second proportional coefficient can be 1. The BCU can obtain the current temperature of the battery cell from the BMU. Specifically, the BMU can collect the current temperature of the battery cell and send the collected current temperature of the battery cell to the BCU. The BCU queries the pre-stored correspondence between the temperature of the battery cell and the OCV-SOC curve to find the OCV-SOC curve corresponding to the current temperature of the battery cell. The BCU determines the specified point on the OCV-SOC curve corresponding to the current temperature using the OCV-SOC curve corresponding to the current temperature. The BCU calculates the absolute value of the tangent slope at the specified point and uses the absolute value of the tangent slope as the first proportional coefficient. The BCU subtracts the first proportional coefficient from 1 to generate the second proportional coefficient.

[0111] For a detailed description of how the BCU retrieves the OCV-SOC curve corresponding to the current temperature of the battery cell from the pre-stored correspondence between the cell's temperature and the OCV-SOC curve, please refer to the description in step 1062 above, which will not be repeated here.

[0112] During the SOC calibration process, a proportionality coefficient derived from the current temperature and the OCV-SOC curve was used. This took into account the impact of temperature on SOC accuracy and further reduced the error of the SOC calculated by the ampere-hour integration method, thereby further improving the accuracy of the calibrated SOC.

[0113] As an optional approach, step 108 may further include: the BCU sending the calibrated SOC to the SCU so that the SCU can display the calibrated SOC.

[0114] As an optional approach, step 108 may also include: the BCU resetting the first set time period and continuing to execute step 102.

[0115] In this embodiment, after the first time period ends, the BCU can reset the first set time period, that is, restart the timing for the first set time period. This scheme allows the BCU to continue calibrating the first SOC calculated by the ampere-hour integration method, thereby achieving real-time calibration of the first SOC.

[0116] In this embodiment of the application, before step 108, the method may further include: Step S1: The BCU calculates the second parameters of the battery cell using the EKF algorithm based on a second-order RC circuit to generate the second SOC of the battery cell at multiple times.

[0117] For example, the second parameter may include SOC, current, ohmic internal resistance, polarization internal resistance, polarization capacitance, and polarization voltage.

[0118] In this embodiment of the application, the execution order between step S1 and other steps is not limited. For example, step 102 and step S1 can be executed simultaneously.

[0119] As an alternative, Figure 5 A flowchart illustrating a method for generating a second SOC provided in this application embodiment is shown below. Figure 5 As shown, step S1 may specifically include: Step S11: Based on the ampere-hour integral equation and the RC voltage equation of the second-order RC circuit, the BCU constructs the state equation and observation equation.

[0120] As an alternative, the ampere-hour integral equation can be... ,in, Let k be the SOC at the current time. For the previous moment SOC, The current of the battery cell, Sampling time, This is the rated capacitance of the battery cell.

[0121] As an alternative, the RC voltage equation for a first-order RC circuit can be: ,in, For polarization internal resistance, Polarized capacitor, Let k-1 be the current in the RC circuit at the previous moment. The polarization voltage at the previous moment k-1 is... Let be the polarization voltage at the current time k, where the polarization voltage is the voltage across the parallel polarization internal resistance and polarization capacitor. It should be noted that each first-order RC circuit in a second-order RC circuit can use the RC voltage equation for a first-order RC circuit as described above.

[0122] BCU will integrate SOC, Using I as the state variable, we obtain the state equation and the observation method.

[0123] The state equation is: ; The observation equation is: .

[0124] in, The function for fitting the OCV-SOC curve. For ohmic internal resistance, Let be the polarization voltage of a first-order RC circuit at the current time k. Let k be the polarization voltage of another first-order RC circuit at the current time k. Let k-1 be the polarization voltage of a first-order RC circuit at the previous moment. Let k-1 be the polarization voltage of another first-order RC circuit at the previous moment. Let be the polarization resistance of a first-order RC circuit. For the polarization internal resistance of another first-order RC circuit, The polarization capacitor is a first-order RC circuit. This is the polarization capacitor for another first-order RC circuit.

[0125] Step S12: BCU discretizes the state equation and observation equation to obtain discretized state equation and observation equation.

[0126] BCU simultaneously establishes the state equations and observation equations, and then discretizes these equations to obtain discretized state equations and observation equations.

[0127] The discretized state equation is: ; The discretized observation equation is: .

[0128] in, , , ; , ; , V is the terminal voltage.

[0129] Step S13: BCU calculates the state value through the discretized state equation and the observation value through the discretized observation equation.

[0130] Wherein, the state value is The observed value is .

[0131] Step S14: BCU performs prior prediction based on the state value and generates the predicted value.

[0132] Predicted value .

[0133] Step S15: BCU predicts the error covariance based on the error covariance equation and generates an updated error covariance.

[0134] Updated error covariance ,in, Let k-1 be the error covariance at the previous time step. This represents the process noise at the previous time step k-1.

[0135] Step S16: BCU calculates the Kalman gain using the Kalman gain equation.

[0136] The Kalman gain equation is ,in, For Kalman gain, To measure the noise covariance matrix.

[0137] In step S17, the BCU performs a posteriori correction based on the predicted value, Kalman gain, and observed value to calculate the second SOC.

[0138] BCU uses the formula The second SOC is generated by calculating the predicted values, Kalman gain, and observed values. This is the second SOC.

[0139] Step S18: BCU corrects the updated error covariance based on the Kalman gain and calculates the corrected error covariance.

[0140] BCU uses the formula The updated error covariance is calculated to generate the corrected error covariance, where the corrected error covariance is... .

[0141] In this embodiment of the application, the second SOC is calculated by the EKF algorithm based on the second-order RC circuit shown in steps S11 to S18. The calculated second SOC has higher accuracy and can be used to calibrate the first SOC calculated by the ampere-hour integration method.

[0142] Figure 6 A flowchart of a method for generating a first SOH provided in an embodiment of this application is shown below. Figure 6 As shown, the method includes: Step 302: The BCU generates the cumulative ampere-hour throughput of the battery cell at the current moment based on the ampere-hour throughput at multiple moments of the acquired battery cell.

[0143] In this embodiment of the application, the BCU multiplies the ampere-hour throughput of the battery cell at multiple times by the corresponding temperature coefficient to obtain the multiplication result, and adds the multiplication results of multiple times to generate the cumulative ampere-hour throughput of the battery cell at the current time.

[0144] Specifically, the BCU obtains the temperature of the battery cell at multiple times from the BMU; and retrieves the temperature coefficient corresponding to the temperature at each time from the correspondence between the battery cell's temperature and temperature coefficient.

[0145] As an optional approach, each model of battery cell has a corresponding relationship between temperature and temperature coefficient. That is, the model of the battery cell corresponds to the temperature and temperature coefficient of that battery cell. Therefore, the temperature and temperature coefficient corresponding to the model of the battery cell can be obtained through the model of the battery cell. The temperature and temperature coefficient corresponding to the model of the battery cell is the temperature and temperature coefficient of that battery cell.

[0146] For each battery cell, different temperatures correspond to different temperature coefficients. Therefore, the correspondence between temperature and temperature coefficient can include multiple temperatures and the temperature coefficient corresponding to each temperature. The BCU can then use this correspondence to find the temperature coefficient corresponding to the temperature at different times.

[0147] As an alternative approach, if the temperature at a specific moment does not exist in the temperature-temperature-coefficient correspondence, a second temperature can be determined from among multiple temperatures in the correspondence, where the absolute value of the difference between the second temperature and the temperature at that moment is minimized. The temperature coefficient corresponding to the second temperature is then retrieved from the temperature-temperature-coefficient correspondence, and this coefficient is used as the temperature coefficient corresponding to the temperature at that specific moment. If there are two second temperatures, one can be arbitrarily selected, and its corresponding temperature coefficient can be retrieved from the temperature-temperature-coefficient correspondence, thus becoming the temperature coefficient corresponding to the temperature at that specific moment.

[0148] The temperature of the battery cell can be different at different times, and different battery cell temperatures correspond to different temperature coefficients. The BCU can obtain the temperature of the battery cell at different times from the BMU and query the temperature coefficient corresponding to the temperature of the battery cell at different times. The temperature coefficient can be obtained by querying, which makes the method of obtaining the temperature coefficient simple and easy to implement.

[0149] In this embodiment of the application, the last time among multiple times is the current time. Then the BCU can accumulate the ampere-hour throughput from the first time until it is accumulated to the ampere-hour throughput of the current time, so as to obtain the cumulative ampere-hour throughput of the current time.

[0150] In this embodiment of the application, the BCU considers the effect of temperature when calculating the cumulative ampere-hour throughput, thereby improving the accuracy of the cumulative ampere-hour throughput.

[0151] Step 304: The BCU uses the set cell cyclic aging curve to query the first capacity decay value corresponding to the current cumulative ampere-hour throughput.

[0152] The cyclic aging curve can reflect the correspondence between the cumulative ampere-hour throughput and the capacity decay value. Therefore, the BCU can query the first capacity decay value corresponding to the current cumulative ampere-hour throughput through the cyclic aging curve.

[0153] As an optional solution, each model of battery cell has a corresponding cycle aging curve. That is, there is a corresponding relationship between the model of the battery cell and the cycle aging curve. Therefore, the cycle aging curve corresponding to the model of the battery cell can be obtained through the model of the battery cell. The cycle aging curve corresponding to the model of the battery cell is the cycle aging curve of the battery cell.

[0154] Step 306: The BCU uses the set calendar aging curve of the battery cell to query the second capacity decay value corresponding to the current time.

[0155] The calendar aging curve can reflect the correspondence between time and capacity decay value. Therefore, the BCU can query the second capacity decay value corresponding to the current time through the calendar aging curve.

[0156] As an optional solution, each model of battery cell has a corresponding calendar aging curve. That is, there is a correspondence between the model of the battery cell and the calendar aging curve. Therefore, the calendar aging curve corresponding to the model of the battery cell can be obtained through the model of the battery cell. The calendar aging curve corresponding to the model of the battery cell is the calendar aging curve of the battery cell.

[0157] Step 308: The BCU generates the first SOH of the cell at the current moment based on the first capacity decay value and the second capacity decay value.

[0158] As an alternative, the BCU subtracts the first and second capacity decay values ​​from 100% to generate the first SOH at the current moment. The first SOH can be obtained simply by subtracting the first and second capacity decay values ​​directly from 100%, a calculation method that is simple and easy to implement.

[0159] In this embodiment, the first SOH is calculated based on the cumulative ampere-hour throughput using the cyclic aging curve and the calendar aging curve. The calculation method is simple and easy to implement.

[0160] As an alternative, the method may further include: the BCU sending the first SOH at the current time to the SCU so that the SCU can display the first SOH at the current time.

[0161] As an optional solution, when the battery cell is in a charging state and the cell goes from a lower initial SOC to a full charge SOC, the BCU can perform a method to calibrate the first SOH using the second SOH. This method further includes: Step 310: The BCU calibrates the first SOH of the cell at the current moment using the second SOH of the cell at the current moment, and generates the calibrated SOH at the current moment.

[0162] As an alternative, the BCU can replace the first SOH at the current time with the second SOH at the current time to obtain the calibrated SOH at the current time. The calibrated SOH at the current time is then used as the second SOH at the current time. In other words, the BCU uses the second SOH at the current time as the calibrated SOH at the current time, thereby calibrating the first SOH at the current time. For example, if the first SOH at the current time is 97% and the second SOH at the current time is 96%, then the calibrated SOH at the current time is 96%.

[0163] The second SOH at the current moment can be calculated using the real-time capacity estimation method.

[0164] As an alternative, the following may also be included before step 310: In step S2, the BCU calculates the second SOH of the cell at the current moment using the real-time capacity estimation method.

[0165] In this embodiment of the application, the execution order between step S2 and other steps is not limited. When the above-mentioned working condition occurs, the calculation process of step S2 can be executed.

[0166] In the embodiments of this application, Figure 7 A flowchart of a method for generating a second SOH provided in an embodiment of this application is shown below. Figure 7 As shown, step S2 may specifically include: Step S22: When the battery cell is in the charging state, the BCU records the first cumulative charge amount corresponding to the initial SOC and the second cumulative charge amount corresponding to the full charge SOC. The initial SOC is less than or equal to the set SOC threshold.

[0167] For example, the SOC threshold can be set as needed. For instance, if the SOC threshold is set to 30%, the initial SOC can be 25%, and the full charge SOC is 100%. The BCU can record the first cumulative charge amount corresponding to the initial SOC of 25%, and the second cumulative charge amount corresponding to the full charge SOC of 100%.

[0168] Step S24: The BCU subtracts the first cumulative charging amount from the second cumulative charging amount to generate the actual charging amount.

[0169] Step S26: The BCU multiplies the difference between the full charge SOC and the initial SOC with the cell capacity to generate the theoretical charge amount.

[0170] Step S28: The BCU divides the actual charge amount by the theoretical charge amount to generate the second SOH of the battery cell at the current moment.

[0171] In this embodiment, the actual charge amount generated by subtracting the second cumulative charge amount corresponding to the full charge SOC from the first cumulative charge amount corresponding to the initial SOC is divided by the theoretical charge amount to generate the second SOH of the battery cell at the current moment. This realizes the calculation of the second SOH through real-time capacity estimation, thereby making the calculated SOH more accurate.

[0172] In this embodiment, the BCU calculates the second SOH of the cell at the current moment using the real-time capacity estimation method, and calibrates the first SOH at the current moment using the second SOH at the current moment to generate the calibrated SOH at the current moment, thereby improving the accuracy of SOH.

[0173] As an optional approach, step 310 may further include: the BCU sending the calibrated SOH at the current moment to the SCU so that the SCU can display the calibrated SOH at the current moment.

[0174] As an alternative, step 310 may also include: Step 312: BCU calculates the SOH difference between the first SOH at the current time and the first SOH at any time after the current time.

[0175] The BCU can use the method shown in steps 302 to 308 to calculate the first SOH at any time after the current time; and subtract the first SOH at any time after the current time from the first SOH at the current time to generate the SOH difference.

[0176] For example, if any time after the current time is the first time after the current time (i.e., the time following the current time), then the BCU subtracts the first SOH of the first time after the current time from the first SOH of the current time to generate the SOH difference. For example, if the first SOH of the current time is 97%, and the first SOH of the first time after the current time is 95%, then the SOH difference is 2%.

[0177] For example, if any time after the current time is the second time after the current time (i.e., two times after the current time), then the BCU subtracts the first SOH of the second time after the current time from the first SOH of the current time to generate the SOH difference. For example, if the first SOH of the current time is 97% and the first SOH of the second time after the current time is 93%, then the SOH difference is 4%.

[0178] Step 314: The BCU subtracts the SOH difference from the calibrated SOH at the current time to generate the calibrated SOH at any time after the current time.

[0179] For example, if any time after the current time is the first time after the current time, the BCU subtracts the SOH difference from the calibrated SOH at the current time to generate the calibrated SOH at the first time after the current time. For example, if the second SOH at the current time is 96%, then the calibrated SOH at the current time is 96%. The BCU subtracts the SOH difference of 2% from the calibrated SOH of 96% at the current time to generate the calibrated SOH at the first time after the current time as 94%.

[0180] For example, if any time after the current time is the second time after the current time, the BCU subtracts the SOH difference from the calibrated SOH at the current time to generate the calibrated SOH at the second time after the current time. For instance, if the second SOH at the current time is 96%, then the calibrated SOH at the current time is 96%. The BCU subtracts the SOH difference of 4% from the calibrated SOH at the current time (96%) to generate the calibrated SOH at the first time after the current time, which is 92%.

[0181] In this embodiment, the BCU calculates the SOH difference between the first SOH at the current time and the first SOH at any time after the current time, and subtracts the SOH difference from the calibrated SOH at the current time to generate the calibrated SOH at any time after the current time, thereby improving the accuracy of SOH. The calculation method is simple and easy to implement.

[0182] As an optional approach, step 314 may further include: the BCU sending the calibrated SOH at any time after the current time to the SCU, so that the SCU can display the calibrated SOH at any time after the current time.

[0183] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An energy storage system, characterized in that, include: The system comprises at least one energy storage converter, at least two battery stacks, and multiple buses. Each battery stack is connected to a corresponding bus, and each bus is connected to a corresponding energy storage converter. Each battery stack includes multiple battery clusters, each battery cluster includes a high-voltage box and multiple battery packs connected in series, and each battery pack includes at least one battery cell. A first fuse is provided between each bus and the corresponding energy storage converter, a second fuse is provided in each high-voltage box, and a third fuse is provided in each battery pack. The energy storage system also includes a BCU located in each high-voltage box. The energy storage converter is used to convert the DC power output from the corresponding battery stack into AC power so that the battery stack can output electrical energy. The first fuse is used to blow when the circuit between the busbar and the energy storage converter is short-circuited; the second fuse is used to blow when the circuit inside the high-voltage box is short-circuited; and the third fuse is used to blow when the circuit inside the battery pack is short-circuited. The BCU is used to control the state of the battery cell.

2. The energy storage system according to claim 1, characterized in that, The number of energy storage converters is one; The energy storage converter is specifically used to convert the direct current output from each of the battery stacks into alternating current.

3. The energy storage system according to claim 1, characterized in that, The system comprises two battery stacks, two energy storage converters, and two buses. The two battery stacks include a first battery stack and a second battery stack. The two energy storage converters include a first energy storage converter and a second energy storage converter. The two buses include a first bus and a second bus. The first battery stack is connected to its corresponding first energy storage converter via the first bus. The second battery stack is connected to its corresponding second energy storage converter via the second bus. The first energy storage converter is used to convert the DC power output from the corresponding first battery stack into AC power so that the first battery stack can output electrical energy. The second energy storage converter is used to convert the DC power output from the corresponding second battery stack into AC power, so that the second battery stack can output electrical energy.

4. The energy storage system according to claim 1, characterized in that, The high-voltage box includes a control circuit, one end of which is connected to a corresponding busbar, and the other end of which is connected to one end of a plurality of battery packs connected in series; the control circuit includes a circuit breaker, a first contactor, and a second fuse connected in series. The BCU is used to first control the circuit breaker to open, and then control the first contactor to open.

5. The energy storage system according to claim 1, characterized in that, The BCU is specifically used to calculate the first parameter of the battery cell using the ampere-hour integration method to generate the first SOC of the battery cell at multiple times. Within a first set time period, if it is determined that the state parameter of the battery cell at any time satisfies any calibration condition, the first SOC at the current time is calibrated according to the calibration rule corresponding to the satisfied calibration condition to generate the calibrated SOC.

6. The energy storage system according to claim 1, characterized in that, Specifically, the BCU is used to generate the cumulative ampere-hour throughput of the battery cell at the current moment based on the ampere-hour throughput at multiple moments of the acquired battery cell; to query the first capacity decay value corresponding to the cumulative ampere-hour throughput at the current moment through the set cyclic aging curve of the battery cell; to query the second capacity decay value corresponding to the current moment through the set calendar aging curve of the battery cell; and to generate the first SOH of the battery cell at the current moment based on the first capacity decay value and the second capacity decay value.

7. A control method for an energy storage system, characterized in that, The energy storage system includes: at least one energy storage converter, at least two battery stacks, and multiple buses. Each battery stack is connected to a corresponding bus, and each bus is connected to a corresponding energy storage converter. Each battery stack includes multiple battery clusters, each battery cluster includes a high-voltage box and multiple battery packs connected in series, and each battery pack includes at least one battery cell. A first fuse is provided between each bus and the corresponding energy storage converter, a second fuse is provided in each high-voltage box, and a third fuse is provided in each battery pack. The energy storage system also includes a BCU located in each high-voltage box. The control method for the energy storage system includes: The energy storage converter converts the DC power output from the corresponding battery stack into AC power, so that the battery stack can output electrical energy. The first fuse blows when the circuit between the busbar and the energy storage converter is short-circuited; the second fuse blows when the circuit inside the high-voltage box is short-circuited; and the third fuse blows when the circuit inside the battery pack is short-circuited. The BCU controls the state of the battery cell.

8. The control method for the energy storage system according to claim 7, characterized in that, The BCU controls the state of the battery cell, including: The BCU calculates the first parameters of the battery cell using the ampere-hour integration method to generate the first SOC of the battery cell at multiple times. If the BCU determines that the state parameter of the battery cell at any time within a first set time period meets any calibration condition, it calibrates the first SOC at the current time according to the calibration rule corresponding to the met calibration condition, and generates the calibrated SOC.

9. The control method for the energy storage system according to claim 8, characterized in that, The BCU controls the state of the battery cell, including: If the BCU determines that the state parameters of the battery cell at multiple times do not meet any calibration conditions within a first set time period, it uses the generated second SOC of the battery cell at the current time to calibrate the first SOC at the current time and generates a calibrated SOC. The second SOC of the battery cell at the current moment is generated by the BCU through the EKF algorithm based on the second-order RC circuit to calculate the second parameters of the battery cell.

10. The control method for the energy storage system according to claim 8 or 9, characterized in that, After generating the calibrated SOC, the process also includes: The BCU resets the first set time period and continues to execute the step of calculating the first parameters of the battery cell using the ampere-hour integration method to generate the first SOC of the battery cell at multiple times.

11. The control method for the energy storage system according to claim 8, characterized in that, If the state parameter includes current; if the BCU determines that the state parameter of the battery cell at any time within a first set time period meets any calibration condition, it calibrates the first SOC at the current time according to the calibration rule corresponding to the met calibration condition, generating a calibrated SOC, including: If the BCU determines that the absolute value of the current is less than a set current threshold, and the duration for which the absolute value of the current is less than the set current threshold reaches a set duration, it obtains the current voltage and current temperature of the battery cell from the BMU, queries the OCV-SOC curve corresponding to the current temperature from the correspondence between the battery cell temperature and the OCV-SOC curve, queries the SOC corresponding to the current voltage of the battery cell through the OCV-SOC curve corresponding to the current temperature, and uses the SOC corresponding to the current voltage of the battery cell as the reference SOC. The BCU adjusts the first SOC at the current moment to the reference SOC, so that the calibrated SOC becomes the reference SOC.

12. The control method for the energy storage system according to claim 8, characterized in that, If the state parameters include voltage and current; if the BCU determines that the state parameters of the battery cell at any time within a first set time period meet any calibration condition, it calibrates the first SOC at the current time according to the calibration rule corresponding to the met calibration condition, generating a calibrated SOC, including: If the BCU determines that the current voltage of the battery cell has reached the charging cutoff voltage and the current current of the battery cell has dropped to the cutoff current, it resets the first SOC at the current moment to 100% so that the calibrated SOC is 100%.

13. The control method for the energy storage system according to claim 8, characterized in that, If the state parameter includes voltage; if the BCU determines that the state parameter of the battery cell at any time within a first set time period meets any calibration condition, it calibrates the first SOC at the current time according to the calibration rule corresponding to the met calibration condition, generating a calibrated SOC, including: If the BCU determines that the current voltage of the battery cell has reached the discharge cutoff voltage, it resets the first SOC at the current moment to 0% so that the calibrated SOC is 0%.

14. The control method for an energy storage system according to claim 9, characterized in that, The step of using the generated second SOC of the battery cell at the current moment to calibrate the first SOC at the current moment and generate a calibrated SOC includes: The BCU adds the product of the first SOC at the current time and the corresponding first scaling factor to the product of the second SOC at the current time and the corresponding second scaling factor to generate the calibrated SOC.

15. The control method for the energy storage system according to claim 7, characterized in that, The BCU controls the state of the battery cell, including: The BCU generates the cumulative ampere-hour throughput of the battery cell at the current moment based on the ampere-hour throughput at multiple moments of the acquired battery cell. The BCU uses the set cyclic aging curve of the battery cell to query the first capacity decay value corresponding to the cumulative ampere-hour throughput at the current moment. The BCU uses the set calendar aging curve of the battery cell to query the second capacity decay value corresponding to the current moment. The BCU generates the first SOH of the battery cell at the current moment based on the first capacity decay value and the second capacity decay value.

16. The control method for an energy storage system according to claim 15, characterized in that, The BCU generates the cumulative ampere-hour throughput of the battery cell at the current moment based on the acquired ampere-hour throughput at multiple times, including: The BCU multiplies the ampere-hour throughput of the battery cell at multiple moments by the corresponding temperature coefficient to obtain the multiplication result, and adds the multiplication results of multiple moments to generate the cumulative ampere-hour throughput of the battery cell at the current moment.

17. The control method for an energy storage system according to claim 15, characterized in that, The BCU generates the first SOH of the battery cell at the current moment based on the first capacity decay value and the second capacity decay value, including: The BCU subtracts the first capacity decay value and the second capacity decay value from 100% to generate the first SOH at the current moment.

18. The control method for an energy storage system according to claim 15, characterized in that, The BCU controls the state of the battery cell, including: The BCU calculates the second SOH of the battery cell at the current moment using a real-time capacity estimation method. The BCU calibrates the first SOH of the battery cell at the current moment using the second SOH of the battery cell at the current moment, and generates the calibrated SOH at the current moment.

19. The control method for an energy storage system according to claim 18, characterized in that, The BCU calculates the second SOH of the battery cell at the current moment using a real-time capacity estimation method, including: When the battery cell is in a charging state, the BCU records the first cumulative charge amount corresponding to the initial SOC and the second cumulative charge amount corresponding to the full charge SOC, wherein the initial SOC is less than or equal to a set SOC threshold. The BCU subtracts the first cumulative charge amount from the second cumulative charge amount to generate the actual charge amount; The BCU multiplies the difference between the full charge SOC and the initial SOC by the capacity of the battery cell to generate the theoretical charging amount. The BCU divides the actual charge amount by the theoretical charge amount to generate the second SOH of the battery cell at the current moment.

20. The control method for an energy storage system according to claim 18, characterized in that, The BCU calibrates the first SOH of the battery cell at the current moment using the second SOH of the battery cell at the current moment, and after generating the calibrated SOH at the current moment, it also includes: The BCU calculates the SOH difference between the first SOH at the current time and the first SOH at any time after the current time; The BCU subtracts the SOH difference from the calibrated SOH at the current time to generate the calibrated SOH at any time after the current time.

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