Battery overdischarge prevention control method and device, and energy storage system

Abstract

The application discloses a battery overdischarge prevention control method and device and an energy storage system, and relates to the technical field of energy storage. The battery overdischarge prevention control method comprises the following steps: acquiring the SoC of a battery and the voltage across the battery, determining the overdischarge level of the battery according to the SoC of the battery and / or the voltage across the battery, acquiring the connection state of a voltage conversion circuit and an external power supply, adjusting the SoC of the battery according to the overdischarge level of the battery and / or the connection state of the voltage conversion circuit and the external power supply, determining the maximum discharge current of the battery according to the adjusted SoC of the battery and a preset discharge cutoff SoC, and finally controlling the opening and closing states of first and second switching devices according to the overdischarge level of the battery and / or the connection state of the voltage conversion circuit and the external power supply, and controlling the charging and discharging of the battery according to the maximum discharge current of the battery. In this way, the battery can be protected step by step when the battery has a low power, so that overdischarge of the battery is prevented, and the safety and reliability of the battery are improved.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to battery over-discharge control methods and devices, and energy storage systems. Background Technology

[0002] Energy storage systems can store electrical energy output from external power generation equipment, or output excess electrical energy from external power generation equipment to the power grid for storage, so as to provide a stable power supply when external loads need it. In addition, energy storage systems can also obtain and store electrical energy from the power grid to meet the power supply needs of external loads.

[0003] Energy storage systems typically store electrical energy using batteries. However, in practical applications, over-discharge of batteries not only shortens their lifespan but can also cause irreversible damage to their performance. Current over-discharge protection technologies generally stop the battery from discharging when its charge level falls below a preset value. However, external power sources and the corresponding battery management circuitry still consume battery power, leading to over-discharge and resulting in lower battery safety and reliability. Summary of the Invention

[0004] The main purpose of this application is to provide a battery over-discharge control method and device, and an energy storage system, which aims to improve the safety and reliability of batteries.

[0005] To achieve the above objectives, this application proposes a battery over-discharge prevention control method, applied to an energy storage system, wherein the energy storage system includes:

[0006] Battery;

[0007] Battery management circuitry, electrically connected to the battery;

[0008] A first switching device, wherein a first terminal of the first switching device is connected to the battery, and a second terminal of the first switching device is connected to the battery management circuit;

[0009] A transformer circuit, wherein the first terminal of the transformer circuit is connected to the battery, and the second terminal of the transformer circuit is used to connect to an external power source;

[0010] A second switching device, wherein a first terminal of the second switching device is connected to a third terminal of the first switching device, and a second terminal of the second switching device is connected to a first terminal of the transformer circuit;

[0011] The battery over-discharge prevention control method includes:

[0012] Obtain the battery's SoC and the voltage across the battery terminals, and determine the battery's over-discharge level based on the battery's SoC and / or the voltage across the battery terminals;

[0013] Obtain the connection status between the transformer circuit and the external power supply;

[0014] Adjust the battery's SoC according to the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply;

[0015] The maximum discharge current of the battery is determined based on the adjusted SoC of the battery and the preset discharge cutoff SoC.

[0016] Based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, the opening and closing states of the first and second switching devices are controlled, and the battery charging and discharging are controlled based on the battery's maximum discharge current.

[0017] In one embodiment, the step of obtaining the battery's SoC and the voltage across the battery terminals, and determining the battery's over-discharge level based on the battery's SoC and / or the voltage across the battery terminals includes:

[0018] Obtain the battery's SoC, the voltage across the battery terminals, the preset SoC, the first preset voltage threshold, the second preset voltage threshold, the third preset voltage threshold, and the fourth preset voltage threshold;

[0019] When the battery's SoC is lower than a preset SoC and the voltage across the battery is greater than a first preset voltage, or when the voltage across the battery is greater than the first preset voltage and less than a second preset voltage, the battery is determined to be in a first-level over-discharge state.

[0020] When the voltage across the battery is greater than a third voltage threshold and less than a first preset voltage threshold, the battery is determined to be in a secondary over-discharge state.

[0021] When the voltage across the battery is less than a third preset voltage threshold and greater than a fourth preset voltage threshold, the battery is determined to be in a level three over-discharge state.

[0022] When the voltage across the battery is less than a fourth preset voltage threshold, the battery is determined to be in a level four over-discharge state.

[0023] Among them, the first preset voltage threshold is less than the second preset voltage threshold, the third preset voltage threshold is less than the first preset voltage threshold, and the fourth preset voltage threshold is less than the third preset voltage threshold.

[0024] In one embodiment, the step of adjusting the battery's SoC based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply includes:

[0025] When the battery is in a secondary over-discharge state, the SoC of the battery is calibrated to a preset discharge cutoff SoC;

[0026] When the battery is in a three-stage over-discharge state and the transformer circuit is connected to an external power source, the SoC of the battery is assigned a preset SoC that is less than the preset discharge cutoff SoC.

[0027] In one embodiment, the step of determining the maximum discharge current of the battery based on the adjusted battery SoC and the preset discharge cutoff SoC includes:

[0028] When the adjusted SoC of the battery is greater than or equal to the preset discharge cutoff SoC, the maximum discharge current of the battery is determined to be not less than the preset current threshold.

[0029] When the battery's SoC is less than the preset discharge cutoff SoC, the maximum discharge current of the battery is determined to be less than the preset current threshold.

[0030] In one embodiment, the step of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, includes:

[0031] When the battery is in a first-stage over-discharge state or a second-stage over-discharge state, the first and second switching devices are controlled to be in a closed state, and the discharge rate of the battery is adjusted based on the maximum discharge current of the battery.

[0032] In one embodiment, the step of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, includes:

[0033] When the battery is in a three-stage over-discharge state and the transformer circuit is connected to an external power source, the first and second switching devices are controlled to be in a closed state, and when the maximum discharge current of the battery is less than a preset current threshold, the power from the external power source is output to the battery to charge the battery.

[0034] In one embodiment, the step of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, includes:

[0035] When the battery is in a three-stage over-discharge state and the transformer circuit is not connected to an external power source, the first switching device is controlled to be in a closed state and the second switching device is controlled to be in an open state, so as to stop the battery from discharging.

[0036] In one embodiment, the step of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, includes:

[0037] When the battery is in a three-stage over-discharge state and the transformer circuit is not connected to an external power source, after the battery continues to discharge for a first preset time, the second switching device is controlled to be in an open state to stop the battery from continuing to discharge.

[0038] In one embodiment, the step of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, includes:

[0039] When the battery is in a level 4 over-discharge state, both the first and second switching devices are turned off to stop the battery management circuit from continuing to consume battery power.

[0040] In addition, to achieve the above objectives, this application also proposes a battery over-discharge protection control device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the battery over-discharge protection control method.

[0041] Furthermore, to achieve the above objectives, this application also proposes an energy storage system, which includes:

[0042] Battery;

[0043] A transformer circuit, wherein the first terminal of the transformer circuit is connected to the battery, and the second terminal of the transformer circuit is used to connect to an external power source;

[0044] The energy storage system uses the battery over-discharge protection control method described above, or the energy storage system includes the battery over-discharge protection control device described above.

[0045] The battery over-discharge prevention control method proposed in this application obtains the battery's SoC and the voltage across the battery terminals, determines the battery's over-discharge level based on the SoC and / or the voltage, acquires the connection status of the transformer circuit and the external power supply, adjusts the battery's SoC based on the over-discharge level and / or the connection status, and determines the battery's maximum discharge current based on the adjusted SoC and a preset discharge cutoff SoC. Finally, it controls the opening and closing states of the first and second switching devices based on the over-discharge level and / or the connection status of the transformer circuit and the external power supply, and controls the battery's charging and discharging based on the maximum discharge current. Thus, this application can provide step-by-step protection for the battery when its charge is low, either by disconnecting the battery's discharge path or by replenishing the battery when conditions are met, thereby preventing over-discharge and improving battery safety and reliability. Attached Figure Description

[0046] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A flowchart illustrating an embodiment of the battery over-discharge prevention control method of this application;

[0049] Figure 2 This is a flowchart illustrating another embodiment of the battery over-discharge control method of this application.

[0050] Figure 3 This is a flowchart illustrating yet another embodiment of the battery over-discharge control method of this application;

[0051] Figure 4 This is a flowchart illustrating another embodiment of the battery over-discharge control method of this application.

[0052] Figure 5 This application provides a schematic flowchart of another embodiment of the battery over-discharge prevention control method.

[0053] Figure 6 This is a flowchart illustrating another embodiment of the battery over-discharge control method of this application.

[0054] Figure 7 This is a flowchart illustrating yet another embodiment of the battery over-discharge control method of this application;

[0055] Figure 8 This is a flowchart illustrating another embodiment of the battery over-discharge control method of this application.

[0056] Figure 9 This application provides a schematic flowchart of another embodiment of the battery over-discharge prevention control method.

[0057] Figure 10 This is a control flowchart provided for an embodiment of the battery over-discharge prevention control method of this application;

[0058] Figure 11 A flowchart illustrating an embodiment of the battery over-discharge prevention control method of this application;

[0059] Figure 12 A schematic diagram of the circuit structure provided for an embodiment of the battery over-discharge control device of this application;

[0060] Figure 13 A schematic diagram of the circuit structure provided for an embodiment of the battery over-discharge control device of this application;

[0061] Figure 14 This is a schematic diagram of the circuit structure provided for an embodiment of the energy storage system of this application.

[0062] Explanation of icon numbers:

[0063] 100. Energy storage circuit; 110. Battery; PACK1. First battery pack; PACKn. Nth battery pack; BMU1. First battery detection unit; BMUn. Nth battery detection unit; KT2. Second switching device; 120. Heating element; QF+MX. First switching device; KT3. Third switching device; 200. Transformer circuit; 210. First transformer circuit; 220. Second transformer circuit; 230. Inverter circuit; KT1. Fourth switching device; L. Inductor; CLbus. First capacitor; CHbus. Second capacitor; S1. First switching transistor; S2. Second switching transistor; Ubat0. Voltage across the battery; Ubus. Bus voltage; 10. Memory; 11. First memory; 12. Second memory; 20. Processor; 21. First processor; 22. Second processor; U1. First chip; U2. Second chip.

[0064] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0065] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0066] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0067] The main solution of this application embodiment is: a battery 110 over-discharge prevention control method, applied to an energy storage system, characterized in that the energy storage system includes:

[0068] Battery 110;

[0069] A battery management circuit is electrically connected to the battery 110;

[0070] A first switching device QF+MX, the first terminal of the first switching device QF+MX is connected to the battery 110, and the second terminal of the first switching device QF+MX is connected to the battery management circuit;

[0071] A transformer circuit 200, the first end of which is connected to the battery 110, and the second end of which is used to connect to an external power source;

[0072] The second switching device KT2 has its first terminal connected to the third terminal of the first switching device QF+MX, and its second terminal connected to the first terminal of the transformer circuit 200.

[0073] The over-discharge protection method for battery 110 includes:

[0074] Obtain the SoC of battery 110 and the voltage Ubat0 across the battery terminals, and determine the over-discharge level of battery 110 based on the SoC of battery 110 and / or the voltage Ubat0 across the battery terminals;

[0075] Obtain the connection status between the transformer circuit 200 and the external power supply;

[0076] The SoC of the battery 110 is adjusted according to the over-discharge level of the battery 110 and / or the connection status of the transformer circuit 200 with the external power supply;

[0077] The maximum discharge current of battery 110 is determined based on the adjusted SoC of battery 110 and the preset discharge cutoff SoC.

[0078] Based on the over-discharge level of battery 110 and / or the connection status of transformer circuit 200 with external power supply, the opening and closing states of the first switching device QF+MX and the second switching device KT2 are controlled, and the charging and discharging of battery 110 is controlled according to the maximum discharge current of battery 110.

[0079] In this embodiment, for ease of description, the over-discharge control device for identifying battery 110 will be used as the execution subject in the following description.

[0080] Energy storage systems can store electrical energy output from external power generation equipment, or output excess electrical energy from external power generation equipment to the power grid for storage, so as to provide a stable power supply when external loads need it. In addition, energy storage systems can also obtain and store electrical energy from the power grid to meet the power supply needs of external loads.

[0081] Energy storage systems typically store electrical energy using a battery 110. However, in practical applications, over-discharging the battery 110 not only shortens its lifespan but can also cause irreversible damage to its performance. Existing over-discharge prevention methods for the battery 110 generally stop its external discharge when the battery's charge level falls below a preset value. However, external auxiliary power sources and the corresponding battery management circuitry still consume the battery's charge, leading to over-discharge.

[0082] The solution provided in this application can protect the battery 110 in stages when the battery power is low, thereby disconnecting the discharge path of the battery 110 or replenishing the battery 110 in time when the conditions are met, thereby preventing the battery 110 from being over-discharged and improving the safety and reliability of the battery 110.

[0083] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device capable of performing the above functions, such as a battery 110 over-discharge protection control device. The following description uses the battery 110 over-discharge protection control device as an example to illustrate this embodiment and the subsequent embodiments.

[0084] In view of the problem that the safety and reliability of the battery 110 in the prior art are low, this application provides a method for over-discharge control of the battery 110.

[0085] refer to Figure 14 The energy storage system includes:

[0086] Battery 110;

[0087] A battery management circuit is electrically connected to the battery 110;

[0088] A first switching device QF+MX, the first terminal of the first switching device QF+MX is connected to the battery 110, and the second terminal of the first switching device QF+MX is connected to the battery management circuit;

[0089] A transformer circuit 200, the first end of which is connected to the battery 110, and the second end of which is used to connect to an external power source;

[0090] The second switching device KT2 has its first terminal connected to the third terminal of the first switching device QF+MX, and its second terminal connected to the first terminal of the transformer circuit 200.

[0091] In this embodiment, the energy storage system includes an energy storage circuit 100 and a transformer circuit 200, with the transformer circuit 200 electrically connected to the energy storage circuit 100. The energy storage circuit 100 includes a battery 110, which can be a high-voltage battery 110, a lithium-ion battery 110, a lead-acid battery 110, etc. The number of batteries 110 can be configured as one or more according to actual energy storage needs. The external power source can include an external power generation device or a power grid. The transformer circuit 200 is used to output electrical energy from the external power generation device or the power grid to the energy storage circuit 100, or to output electrical energy from the external power generation device or the power grid to the energy storage circuit 100 to charge the battery 110, or to output electrical energy from the energy storage circuit 100 to the power grid or an external load to discharge the battery 110. Specifically, the energy storage circuit 100 and the transformer circuit 200 can be electrically connected via an external power line, which can be a wire or cable connecting the transformer circuit 200 and the energy storage circuit 100 to achieve power transmission between them.

[0092] It is understood that the external power generation equipment can be renewable energy equipment such as wind turbines, solar photovoltaic panels, and hydroelectric generators, or it can be traditional fossil fuel power generation equipment. The power grid can be the national power grid, local power grid, or an independent microgrid system. The external load can be household electrical equipment, industrial electrical equipment, commercial electrical equipment, etc. The transformer circuit 200 can include bidirectional buck / boost topology circuits, inverter circuits 230, etc., to realize bidirectional flow of electrical energy. That is, in energy storage mode, it converts the electrical energy from the external power generation equipment or the power grid into voltage and current suitable for charging the battery 110 to charge the battery 110 of the energy storage circuit 100; in discharge mode, it converts the electrical energy stored in the battery 110 into voltage and current suitable for the power grid or external load to discharge the battery 110 of the energy storage circuit 100.

[0093] In this embodiment, the first switching device QF+MX and the second switching device KT2 may specifically include a micro-break switch, a relay, a transistor, etc. Since the first terminal of the first switching device QF+MX is connected to the battery 110, the second terminal of the first switching device QF+MX is connected to the battery management circuit, the first terminal of the second switching device KT2 is connected to the third terminal of the first switching device QF+MX, and the second terminal of the second switching device KT2 is connected to the first terminal of the transformer circuit 200, that is, the battery 110 is connected to the power management circuit through the first switching device QF+MX, and the battery 110 is connected to the transformer circuit 200 through the first switching device QF+MX and the second switching device KT2. Through the first switching device QF+MX, the connection between the battery 110 and the energy storage circuit 100 or the battery management circuit can be disconnected when the battery 110 is too low, so as to prevent the auxiliary power source or the power management circuit in the transformer circuit 200 from continuing to work and continue to consume the battery 110, causing the battery 110 to be over-discharged. Furthermore, the first switching device QF+MX can quickly disconnect the battery 110 from the energy storage circuit 100 when the battery 110 malfunctions, preventing the fault from spreading to the entire energy storage system. The second switching device KT2 can disconnect the battery 110 from the transformer circuit 200 when the battery's charge is too low, thus preventing the battery 110 from continuing to discharge under the action of the transformer circuit 200. In this way, even if the battery management circuit or external auxiliary power source is still consuming a small amount of power, the over-discharge phenomenon of the battery 110 can be effectively controlled because the connection between the battery 110 and the external circuit has been disconnected. Moreover, when the battery 110's charge returns to a safe level, the second switching device KT2 can close again, restoring the normal charging and discharging function of the battery 110.

[0094] Reference Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the over-discharge prevention control method for battery 110 in this application.

[0095] In this embodiment, the over-discharge protection control method for battery 110 includes steps S100 to S500:

[0096] Step S100: Obtain the SoC of battery 110 and the voltage Ubat0 across the battery terminals, and determine the over-discharge level of battery 110 based on the SoC of battery 110 and / or the voltage Ubat0 across the battery terminals.

[0097] In this embodiment, the SoC of battery 110 is the remaining percentage of battery capacity. It is understood that the SoC of battery 110 can be obtained through real-time monitoring and calculation by a battery management system (BMS) located in the energy storage circuit 100. The BMS may include multiple sensors for measuring parameters such as voltage, current, and temperature of battery 110, and calculating the SoC of battery 110 using corresponding algorithms. Furthermore, the battery SoC can also be a lower SoC than the actual SoC value of battery 110 that is forcibly assigned by the battery over-discharge prevention control device when battery 110 is at a low charge level, so as to control the transformer circuit 200 to charge battery 110 when battery 110 is at a low charge level. The SoC of battery 110 can reflect the current remaining charge state of battery 110, thereby providing a basis for determining the over-discharge level of battery 110.

[0098] In this embodiment, the energy storage system can be equipped with one or more voltage detection circuits. The battery 110 over-discharge protection control device can obtain the voltage Ubat0 across the battery terminals through these voltage detection circuits. Specifically, the voltage detection circuit can be a voltage divider circuit composed of voltage divider resistors, operational amplifiers, etc. The voltage divider resistors reduce the voltage across the battery 110 terminals to a range suitable for processing by the operational amplifier. The operational amplifier amplifies the voltage signal and converts it into a digital signal so that the battery 110 over-discharge protection device can identify it and calculate according to a preset voltage ratio relationship, thereby obtaining the voltage across the battery 110 terminals. It is understood that, optionally, the energy storage circuit 100 includes one or more battery packs 110 (first battery pack PACK1, second battery pack 110, ..., nth battery pack PACKn, where n is greater than or equal to n), each battery pack 110 having at least one cell, and the aforementioned battery terminal voltage Ubat0 can specifically be the voltage across the cell. In this embodiment, obtaining the battery terminal voltage Ubat0 can also provide a basis for determining the over-discharge level of the battery 110.

[0099] It is understandable that there is a positive correlation between the voltage Ubat0 across the battery and the SoC of the battery 110. The higher the SoC of the battery 110, the higher the voltage across the battery 110; conversely, when the SoC of the battery 110 is low, the voltage across the battery 110 will also decrease. However, in practical applications, when the SoC of the battery 110 is low, for example, close to the preset discharge cutoff SoC, the battery SoC obtained through real-time monitoring and calculation by the battery management system (BMS) located in the energy storage circuit 100 may have errors. The BMS may include multiple sensors to measure parameters such as voltage, current, and temperature of the battery 110 and calculate the SoC of the battery 110 through corresponding algorithms. This may result in the detected SoC being larger than the actual SoC when the actual SoC of the battery 110 is close to the preset discharge cutoff SoC. Therefore, in this case, detecting the voltage Ubat0 across the battery can more accurately determine the current state of charge of the battery 110. Furthermore, when the SoC of the battery 110 is close to the preset discharge cutoff SoC, the change in the voltage Ubat0 across the battery does not significantly reflect the change in the SoC of the battery 110. Therefore, in this embodiment, when the SoC of battery 110 is high, either the SoC of battery 110 or the voltage Ubat0 at both ends of the battery can be used to determine the current over-discharge level of battery 110. When the SoC of battery 110 is close to the preset discharge cutoff SoC, the over-discharge control device of battery 110 will determine the over-discharge level of battery 110 based on the voltage Ubat0 at both ends of the battery.

[0100] In this embodiment, specifically, the over-discharge level of battery 110 can be determined by the relationship between the SoC of battery 110 and a preset SoC, or by the relationship between the voltage Ubat0 across the battery terminals and a preset voltage threshold. For example, when the SoC of battery 110 is greater than or equal to the preset SoC threshold, it can be determined that battery 110 is in a safe state and does not require over-discharge protection. When the SoC of battery 110 is less than the preset SoC threshold but greater than or equal to a lower SoC threshold, it can be determined that battery 110 is in a slightly over-discharged state. At this time, the battery 110 over-discharge protection control device can issue a warning signal to remind the user that the battery 110 is low on power and suggest charging it in time. When the SoC of battery 110 is less than the lower SoC threshold, it can be determined that battery 110 is in a severely over-discharged state. At this time, the battery 110 over-discharge protection control device will activate the protection mechanism, disconnect the connection between battery 110 and external circuit, prevent battery 110 from continuing to discharge, and thus avoid damage to battery 110 due to over-discharge. Similarly, for the voltage Ubat0 across the battery terminals, when it exceeds a preset voltage threshold, battery 110 is in a normal state; when it is below the preset voltage threshold but above a lower voltage threshold, battery 110 is in a slightly over-discharged state; and when it is below the lower voltage threshold, battery 110 is in a severely over-discharged state. The battery 110 over-discharge control device will determine the over-discharge level of battery 110 based on these voltage thresholds and take corresponding protective measures. It is understood that this over-discharge level classification is flexible and can be adjusted according to different types of batteries 110 and application scenarios. For example, for lithium-ion batteries 110, the preset SoC threshold and voltage threshold may differ from those for lead-acid batteries 110 because different types of batteries 110 have different discharge characteristics and safety requirements. In practical applications, the battery 110 over-discharge control device will set these thresholds based on the specific type of battery 110 and data provided by the manufacturer. Furthermore, the battery 110 over-discharge control device can also dynamically adjust these thresholds based on the battery 110's usage history and aging condition to ensure the safety and performance of battery 110 during long-term use.

[0101] In this embodiment, by determining the over-discharge level of battery 110, the over-discharge protection control device of battery 110 can take corresponding measures to protect battery 110 and prevent battery 110 from over-discharge.

[0102] Step S200: Obtain the connection status between the transformer circuit 200 and the external power supply.

[0103] In this embodiment, the external power source may include external power generation equipment or a power grid. The external power generation equipment may be renewable energy equipment such as wind turbines, solar photovoltaic panels, and hydroelectric generators, or it may be traditional fossil fuel power generation equipment. The power grid may be a national power grid, a local power grid, or an independent microgrid system. The external load may be household electrical equipment, industrial electrical equipment, commercial electrical equipment, etc.

[0104] In this embodiment, the connection status of the transformer circuit 200 with the external power source can be determined by detecting the voltage and current of the external power generation equipment or the power grid, or by detecting the voltage and current of the port connected to the external power generation equipment or the power grid in the transformer circuit 200. For example, when the port voltage of the transformer circuit 200 connected to the external power generation equipment or the power grid is detected to be greater than a certain set threshold, it can be considered that the transformer circuit 200 is connected to the external power source. If the port voltage is lower than the set threshold, it indicates that the transformer circuit 200 is not connected to the external power source or the connection is unstable. After confirming the connection status, the battery 110 over-discharge control device can decide whether to store the electrical energy of the external power source into the battery 110. For example, when the battery 110 has a low charge and the port voltage is higher than the set threshold, the energy storage system can store the excess electrical energy into the battery 110. Conversely, when the battery 110 has a low charge and the external power source is unstable or cannot provide enough electrical energy, the battery 110 over-discharge control device can disconnect the power supply path of the battery 110 to avoid over-discharge of the battery 110.

[0105] Step S300: Adjust the SoC of the battery 110 according to the over-discharge level of the battery 110 and / or the connection status of the transformer circuit 200 with the external power supply.

[0106] In this embodiment, the System-on-Chip (SoC) of battery 110 can be used to calculate the maximum discharge current of battery 110. The maximum discharge current of battery 110 is the maximum allowable discharge current value of battery 110 under the current SoC. By determining the maximum discharge current of battery 110, the discharge rate of battery 110 can be effectively controlled (when the maximum discharge current of battery 110 is not less than a preset current threshold, the larger the maximum discharge current of battery 110, the faster the discharge rate of battery 110). Alternatively, battery 110 can be charged when the battery charge is low and the transformer circuit 200 is connected to an external power source to avoid over-discharge of battery 110 (charge battery 110 when the maximum discharge current of battery 110 is less than a preset current threshold). Specifically, the maximum discharge current of battery 110 can be determined by the relationship between the SoC of battery 110 and the preset discharge cutoff SoC. Let the discharge cutoff SoC be the minimum charge threshold that battery 110 is allowed to discharge. Typically, to protect battery 110 and extend its service life, a safe discharge cutoff SoC is set, such as 20%, 10%, 8%, 5%, 0, etc.

[0107] However, it is understandable that when the SoC of battery 110 is low, such as when it is close to the preset discharge cutoff SoC, the battery SoC may be obtained through real-time monitoring and calculation by the battery management system (BMS) of energy storage circuit 100. The BMS may include multiple sensors to measure parameters such as voltage, current, and temperature of battery 110 and calculate the SoC of battery 110 through corresponding algorithms. This may result in errors in the detection of battery SoC when the actual SoC of battery 110 is close to the preset discharge cutoff SoC. Therefore, by detecting the voltage Ubat0 at both ends of the battery, the current charge state of battery 110 can be determined more accurately. That is, the SoC of battery 110 can be adjusted according to the predetermined over-discharge level to more accurately determine the actual state of battery 110.

[0108] Furthermore, it is understandable that when the preset discharge cutoff SoC is set low, for example, when the preset discharge cutoff SoC is set to 0, the maximum discharge current of battery 110 calculated based on the actual SoC of battery 110 cannot be less than 0, making it impossible to charge battery 110. Therefore, when the battery 110 has a low charge and the transformer circuit 200 is connected to an external power source, the SoC of battery 110 can be adjusted so that the final calculated maximum discharge current value of battery 110 is less than 0, thereby allowing charging of battery 110 and ensuring that the charge of battery 110 can be replenished in a timely manner.

[0109] Step S400: Determine the maximum discharge current of battery 110 based on the adjusted SoC of battery 110 and the preset discharge cutoff SoC.

[0110] In this embodiment, the maximum discharge current of battery 110 can be determined by calculating the difference between the adjusted SoC of battery 110 and the preset discharge cutoff SoC. Specifically, the value of subtracting the preset discharge cutoff SoC from the SoC of battery 110 is first determined, and then the maximum allowable discharge current of battery 110 under the current SoC is calculated based on this difference and the discharge characteristic curve of battery 110. The discharge characteristic curve can be data provided by the battery 110 manufacturer or discharge characteristic data of battery 110 obtained through experimental measurements. Furthermore, the maximum discharge current of battery 110 can also be calculated based on the SoC of battery 110 and the preset discharge cutoff SoC using a preset algorithm or model. By determining the maximum discharge current of battery 110, the discharge rate of battery 110 can be effectively controlled, or battery 110 can be charged when charging conditions are met, thereby preventing over-discharge of battery 110.

[0111] In step S500, based on the over-discharge level of battery 110 and / or the connection status of transformer circuit 200 with external power supply, the opening and closing states of the first switching device QF+MX and the second switching device KT2 are controlled, and the charging and discharging of battery 110 is controlled based on the maximum discharge current of battery 110.

[0112] In this embodiment, the battery 110 over-discharge protection control device determines whether to turn on or off the first switching device QF+MX and the second switching device KT2 based on the over-discharge level of the battery 110. For example, when the SoC of the battery 110 is higher than the preset discharge cutoff SoC, if the over-discharge level of the battery 110 is low, the circuit will allow the battery 110 to discharge. In this case, the battery 110 over-discharge protection control device controls both the first switching device QF+MX and the second switching device KT2 to be in the closed state. The battery 110 supplies power to the load through the transformer circuit 200, and the discharge rate of the battery 110 is controlled by the maximum discharge current of the battery 110. If the over-discharge level of the battery 110 is high, and the transformer circuit 200 is not connected to an external power source, the battery 110 over-discharge protection control device controls the first switching device QF+MX to be in the closed state and controls the second switching device KT2 to be in the open state to stop the battery 110 from discharging through the transformer circuit 200. 0 supplies power to the load; if the over-discharge level of battery 110 is high and transformer circuit 200 is connected to an external power source, the battery 110 over-discharge protection control device controls the first switching device QF+MX and the second switching device KT2 to be in the closed state, so that battery 110 can be charged through the external power source, thereby avoiding over-discharge of battery 110; in addition, if the over-discharge level of battery 110 is extremely high, the battery 110 over-discharge protection control device controls the first switching device QF+MX and the second switching device KT2 to be in the open state, so as to stop battery 110 from discharging to the load through transformer circuit 200, and at the same time prevent the auxiliary power source and power management circuit in transformer circuit 200 from continuing to work and continue to consume the battery 110 power, causing battery 110 to be over-discharged.

[0113] In this embodiment, the over-discharge level of battery 110 is determined by acquiring the SoC and the voltage Ubat0 across the battery terminals, and then the connection status of transformer circuit 200 with external power supply is acquired. The SoC of battery 110 is then adjusted based on the over-discharge level and / or the connection status of transformer circuit 200 with external power supply. The maximum discharge current of battery 110 is determined based on the adjusted SoC and a preset discharge cutoff SoC. Finally, the opening and closing states of the first switching device QF+MX and the second switching device KT2 are controlled based on the over-discharge level and / or the connection status of transformer circuit 200 with external power supply, and the charging and discharging of battery 110 is controlled based on the maximum discharge current. Thus, this application can provide step-by-step protection for battery 110 when its charge is low, either by disconnecting the discharge path of battery 110 or by replenishing the battery 110 with charge when conditions are met, thereby preventing over-discharge and improving the safety and reliability of battery 110.

[0114] In one feasible implementation, refer to Figure 2 Step S100 includes steps S110 to S120, wherein:

[0115] Step S110: Obtain the SoC of battery 110, the voltage Ubat0 at both ends of battery 110, the preset SoC, the first preset voltage threshold, the second preset voltage threshold, the third preset voltage threshold and the fourth preset voltage threshold.

[0116] In this embodiment, the energy storage system can be equipped with one or more voltage detection circuits. The battery 110 over-discharge protection control device can obtain the voltage Ubat0 across the battery terminals through these voltage detection circuits. Specifically, the voltage detection circuit can be a voltage divider circuit composed of voltage divider resistors, operational amplifiers, etc. The voltage divider resistors reduce the voltage across the battery 110 terminals to a range suitable for processing by the operational amplifier. The operational amplifier amplifies the voltage signal and converts it into a digital signal so that the battery 110 over-discharge protection device can identify it and calculate according to a preset voltage ratio relationship, thereby obtaining the voltage across the battery 110 terminals. It is understood that, optionally, the energy storage circuit 100 includes one or more battery packs 110 (first battery pack PACK1, second battery pack 110, ..., nth battery pack PACKn, where n is greater than or equal to n), each battery pack 110 having at least one cell, and the aforementioned battery terminal voltage Ubat0 can specifically be the voltage across the cell. In this embodiment, obtaining the battery terminal voltage Ubat0 can also provide a basis for determining the over-discharge level of the battery 110.

[0117] In this embodiment, the preset SoC can be a battery SoC serving as a warning. When the SoC of battery 110 is lower than the preset SoC, it can alert the user that the battery 110 has insufficient power. The first preset voltage threshold can be the battery voltage Ubat0 corresponding to the battery SoC being the preset SoC. The second preset voltage threshold can be the battery voltage Ubat0 corresponding to the actual SoC of battery 110 being equal to the preset discharge cutoff SoC, and this second preset voltage threshold is lower than the first preset voltage threshold. As can be seen from the above embodiment, when the actual SoC of battery 110 is close to the preset discharge cutoff SoC, the detected battery SoC is larger than the actual battery SoC. Therefore, when the voltage of battery 110 reaches the second preset voltage threshold, the battery 110 stops discharging externally to avoid over-discharge of battery 110. The third preset voltage threshold can be set lower than the second preset voltage threshold. When the voltage Ubat0 across the battery terminals is lower than this third preset voltage threshold, to ensure that the battery 110 is not over-discharged, the system will further control the second switching device KT2 to be in the open state, so as to prevent the auxiliary power source in the transformer circuit 200 from continuously consuming the battery 110's power and causing the battery 110 to over-discharge. At the same time, when the transformer circuit 200 is connected to an external power generation device, the system will control the second switching device KT2 to be in the closed state, so that the external power generation device can charge the battery 110 through the transformer circuit 200. The fourth preset voltage threshold is set to be lower than the third preset voltage threshold, ensuring that the battery management circuit stops working when the battery 110's power reaches the over-discharge danger zone. This can maximize the protection of the battery 110 and prevent further over-discharge of the battery 110 due to the consumption of the battery management circuit.

[0118] Furthermore, to ensure that the battery 110 is not damaged under extreme conditions, the battery 110 over-discharge protection control device can also issue a warning signal to the user through the battery management circuit when the voltage Ubat0 across the battery terminals is less than the fourth preset voltage threshold. The warning signal can be displayed on a screen, emitted as an audible alarm, or communicated to the user through other means. This allows the user to take timely measures when the battery 110's charge is too low, such as manually closing the first switching device QF+MX and connecting an external power source for charging, thereby replenishing the battery 110. In practical applications, the preset SoC, the first preset voltage threshold, the second preset voltage threshold, the third preset voltage threshold, and the fourth preset voltage threshold can be adjusted according to the type and capacity of the battery 110 and the actual usage environment; their specific values ​​are not limited here.

[0119] In step S120, when the SoC of the battery 110 is lower than a preset SoC and the voltage Ubat0 across the battery is greater than a first preset voltage, or when the voltage Ubat0 across the battery is greater than the first preset voltage and less than a second preset voltage, the battery 110 is determined to be in a first-level over-discharge state; when the voltage Ubat0 across the battery is greater than a third voltage threshold and less than a first preset voltage threshold, the battery 110 is determined to be in a second-level over-discharge state; when the voltage Ubat0 across the battery is less than a third preset voltage threshold and greater than a fourth preset voltage threshold, the battery 110 is determined to be in a third-level over-discharge state; when the voltage Ubat0 across the battery is less than a fourth preset voltage threshold, the battery 110 is determined to be in a fourth-level over-discharge state.

[0120] In this embodiment, the battery 110 over-discharge control device can divide the over-discharge state of the battery 110 into four levels based on the SoC of the battery 110 and / or the voltage Ubat0 at both ends of the battery when the battery 110 has a low charge, so as to facilitate subsequent control of the energy storage system based on each over-discharge level, thereby preventing the battery 110 from being over-discharged.

[0121] In one feasible implementation, refer to Figure 3 The step of adjusting the SoC of the battery 110 according to the over-discharge level of the battery 110 and / or the connection status of the transformer circuit 200 with the external power supply includes step S310, whereby when the battery 110 is in the second-level over-discharge state, the SoC of the battery 110 is calibrated to a preset discharge cutoff SoC; and when the battery 110 is in the third-level over-discharge state and the transformer circuit 200 is connected to the external power supply, the SoC of the battery 110 is assigned a preset SoC that is less than the preset discharge cutoff SoC.

[0122] In this embodiment, it is understood that in practical applications, when the SoC of battery 110 is low, for example, close to the preset discharge cutoff SoC, the battery SoC is obtained through real-time monitoring and calculation by the battery management system (BMS) located in the energy storage circuit 100. The BMS may include multiple sensors to measure parameters such as voltage, current, and temperature of battery 110, and calculate the SoC of battery 110 using corresponding algorithms. This may result in errors, causing the detected battery SoC to be larger than the actual battery SoC when the actual SoC of battery 110 is close to the preset discharge cutoff SoC. Therefore, detecting the voltage Ubat0 across the battery terminals can more accurately determine the current state of charge of battery 110. Thus, when battery 110 is in a secondary over-discharge state, calibrating the SoC of battery 110 to the preset discharge cutoff SoC can more accurately determine the actual state of battery 110, thereby avoiding over-discharge of battery 110.

[0123] In one feasible implementation, the preset discharge cutoff SoC is set to 0. When the battery 110 is in a secondary over-discharge state, the SoC of the battery 110 is calibrated to 0, which can more accurately determine the actual state of the battery 110, thereby avoiding over-discharge of the battery 110.

[0124] In this embodiment, when the battery 110 is in a third-level over-discharge state, i.e., the voltage Ubat0 across the battery terminals is lower than the third preset voltage threshold, the second switching device KT2 is controlled to be in a closed state when the transformer circuit 200 is connected to an external power generation device, so that the external power supply charges the battery 110 through the transformer circuit 200. Referring to the above embodiment, at this time, it is necessary to make the maximum discharge current of the battery 110 less than the preset current threshold. Therefore, the battery 110 over-discharge protection control device assigns the SoC of the battery 110 to a preset SoC that is lower than the preset discharge cutoff SoC, so that the maximum discharge current of the battery 110 is less than the preset current threshold, thereby controlling the external power supply to charge the battery 110 through the transformer circuit 200.

[0125] In one feasible implementation, refer to Figure 4 The step of determining the maximum discharge current of battery 110 based on the adjusted SoC of battery 110 and the preset discharge cutoff SoC includes step S410: when the adjusted SoC of battery 110 is greater than or equal to the preset discharge cutoff SoC, the maximum discharge current of battery 110 is determined to be not less than a preset current threshold; when the SoC of battery 110 is less than the preset discharge cutoff SoC, the maximum discharge current of battery 110 is determined to be less than the preset current threshold.

[0126] In this embodiment, when the SoC of the adjusted battery 110 is much higher than the preset discharge cutoff SoC, the difference between the SoC of the battery 110 and the preset discharge cutoff SoC is large, and the maximum discharge current of the battery 110 is much greater than the preset current threshold. When the SoC of the adjusted battery 110 is higher than the preset discharge cutoff SoC, but the difference between the SoC of the battery 110 and the preset discharge cutoff SoC is small, the maximum discharge current of the battery 110 is also greater than the preset current threshold, but relatively small. When the SoC of the adjusted battery 110 is equal to the preset discharge cutoff SoC, the difference between the SoC of the battery 110 and the preset discharge cutoff SoC is 0, and the maximum discharge current of the battery 110 is the preset current threshold, that is, the battery 110 is not allowed to discharge at this time. When the SoC of the adjusted battery 110 is lower than the preset discharge cutoff SoC, the maximum discharge current of the battery 110 is less than the preset current threshold, and the battery 110 charging and discharging control device controls the transformer circuit 200 to charge the battery 110 when connected to an external power generation device or connected to the power grid.

[0127] In this embodiment, reference is made to Figure 10The maximum discharge current of battery 110 can also be determined by the correspondence between the battery SoC, the preset discharge cutoff SoC, and the difference between the preset battery SoC and the preset discharge cutoff SoC, and the maximum discharge current of battery 110. The correspondence between the difference between the preset battery SoC and the preset discharge cutoff SoC and the maximum discharge current of battery 110 can be a positive correlation. For details, please refer to... Figure 9 The maximum discharge current of battery 110 can be determined using the following formula.

[0128] I L_ref =(SoC-SoC) low_ ref)×P;

[0129] Among them, I L_ref The maximum discharge current of battery 110, SoC is the battery SoC, SoC low_ ref represents the preset discharge cutoff SoC, and P represents the filter coefficient. Thus, in practical applications, the filter coefficient P can be adjusted according to factors such as the type and capacity of battery 110 and the usage environment to ensure that the maximum discharge current of battery 110 matches the actual state of battery 110. In this embodiment, the preset current threshold can be 0. When the maximum discharge current of battery 110 is less than 0, the external power supply is controlled to replenish the battery 110 through the transformer circuit 200.

[0130] In one feasible implementation, refer to Figure 5 The step of controlling the opening and closing states of the first switching device QF+MX and the second switching device KT2 according to the over-discharge level of the battery 110 and / or the connection state of the transformer circuit 200 with the external power supply, and controlling the charging and discharging of the battery 110 according to the maximum discharge current of the battery 110 includes step S510, in which the first switching device QF+MX and the second switching device KT2 are controlled to be in the closed state when the battery 110 is in the first-level over-discharge state or the second-level over-discharge state, and the discharge rate of the battery 110 is adjusted based on the maximum discharge current of the battery 110.

[0131] In this embodiment, when the battery 110 is in a first-level over-discharge state, i.e., when the SoC of the battery 110 is lower than a preset SoC and the voltage Ubat0 across the battery is greater than a first preset voltage, or when the voltage Ubat0 across the battery is greater than the first preset voltage and less than a second preset voltage, the battery 110 over-discharge control device controls the first switching device QF+MX and the second switching device KT2 to be in a closed state. At this time, the SoC of the battery 110 is higher than the preset discharge cutoff SoC, and the battery 110 is allowed to discharge. However, since the SoC of the battery 110 is relatively close to the preset discharge cutoff SoC, the calculated maximum allowable discharge current of the battery 110 is relatively small, thereby limiting the discharge rate of the battery 110 to a certain extent and reducing the energy consumption of the battery 110. It can be understood that when the battery 110 continues to discharge, the battery SoC will continue to decrease, thereby further limiting the discharge rate of the battery 110.

[0132] In this embodiment, when the battery 110 is in a secondary over-discharge state, that is, when the voltage Ubat0 across the battery terminals is greater than the third voltage threshold and less than the first preset voltage threshold, the battery 110 over-discharge control device controls the first switching device QF+MX and the second switching device KT2 to remain in the closed state. Referring to the above embodiment, since the battery 110 is in the secondary over-discharge state, the SoC of the battery 110 is calibrated to the preset discharge cutoff SoC, that is, the SoC of the battery 110 is equal to the preset discharge cutoff SoC, so that the calculated maximum allowable discharge current of the battery 110 is 0, the battery 110 is not allowed to charge or discharge, that is, the battery 110 is stopped from continuing to supply power to the load through the transformer circuit 200, so as to avoid over-discharge of the battery 110.

[0133] In one feasible implementation, refer to Figure 6 , Figure 11 The step of controlling the opening and closing states of the first switching device QF+MX and the second switching device KT2 according to the over-discharge level of the battery 110 and / or the connection state of the transformer circuit 200 with the external power supply, and controlling the charging and discharging of the battery 110 according to the maximum discharge current of the battery 110, includes step S520: when the battery 110 is in the third-level over-discharge state and the transformer circuit 200 is connected to the external power supply, the first switching device QF+MX and the second switching device KT2 are controlled to be in the closed state, and when the maximum discharge current of the battery 110 is less than a preset current threshold, the power of the external power supply is output to the battery 110 to charge the battery 110.

[0134] In this embodiment, when the battery 110 is in a three-stage over-discharge state, that is, when the voltage Ubat0 across the battery is less than a third preset voltage threshold and greater than a fourth preset voltage threshold, and when the transformer circuit 200 is connected to an external power source, the first switching device QF+MX and the second switching device KT2 are controlled to be in a closed state. Referring to the above embodiment, since the battery 110 is in a three-stage over-discharge state and the transformer circuit 200 is connected to an external power source, the SoC of the battery 110 is assigned a preset SoC that is less than the preset discharge cutoff SoC, so that the calculated maximum allowable discharge current of the battery 110 is less than 0, the battery 110 over-discharge protection device controls the external power source to charge the battery 110 through the transformer circuit 200.

[0135] In one feasible implementation, refer to Figure 7 , Figure 11 The step of controlling the opening and closing states of the first switching device QF+MX and the second switching device KT2 according to the over-discharge level of the battery 110 and / or the connection state of the transformer circuit 200 with the external power supply, and controlling the charging and discharging of the battery 110 according to the maximum discharge current of the battery 110 includes step S530, when the battery 110 is in the third-level over-discharge state and the transformer circuit 200 is not connected to the external power supply, controlling the first switching device QF+MX to be in the closed state and the second switching device KT2 to be in the open state, so that the battery 110 stops discharging.

[0136] In this embodiment, when the battery 110 is in a three-stage over-discharge state, that is, when the voltage Ubat0 across the battery is less than the third preset voltage threshold and greater than the fourth preset voltage threshold, and when the transformer circuit 200 is not connected to an external power source, the first switching device QF+MX is controlled to be in a closed state and the second switching device KT2 is in an open state, that is, the power transmission channel between the battery 110 and the transformer circuit 200 is disconnected, thereby stopping the battery 110 from continuing to discharge through the transformer circuit 200, and at the same time preventing the auxiliary power source in the transformer circuit 200 from continuing to consume the battery 110's power, thereby preventing the battery 110 from being over-discharged.

[0137] In one feasible implementation, refer to Figure 8 , Figure 11 The step of controlling the opening and closing states of the first switching device QF+MX and the second switching device KT2 according to the over-discharge level of the battery 110 and / or the connection state of the transformer circuit 200 with the external power supply, and controlling the charging and discharging of the battery 110 according to the maximum discharge current of the battery 110 includes step S531, when the battery 110 is in the third-level over-discharge state and the transformer circuit 200 is not connected to the external power supply, after the battery 110 continues to discharge for a first preset time, controlling the second switching device KT2 to be in the open state to stop the battery 110 from continuing to discharge.

[0138] In this embodiment, when battery 110 is in a level 3 over-discharge state, immediate measures are needed to prevent further discharge. To ensure that battery 110 is not damaged in extreme cases, the system will activate a preset time delay mechanism. During the delay period, the battery 110 over-discharge control device continuously monitors the voltage and current status of battery 110, as well as the connection status of external power generation equipment or the power grid. If battery 110 is not connected to external power generation equipment or the power grid within the first preset time period, the system will control the first switching device QF+MX2 to disconnect the path between energy storage circuit 100 and transformer circuit 200, thereby stopping battery 110 from continuing to discharge.

[0139] Understandably, the first preset duration can be adjusted based on the type and capacity of the battery 110, as well as the actual usage environment. For example, for a large-capacity battery 110, the preset duration can be set longer to ensure sufficient time for external power generation equipment or grid connection. For a small-capacity battery 110, the preset duration can be relatively shorter to quickly respond to over-discharge conditions. Furthermore, to improve system reliability, multiple preset durations can be set and dynamically adjusted according to the discharge rate and discharge current of the battery 110. For example, when a large discharge current is detected in the battery 110, the system can automatically shorten the preset duration to respond more quickly to over-discharge conditions. Conversely, when the discharge current is small, the preset duration can be appropriately extended to avoid frequent circuit disconnection and reconnection, thereby reducing wear on switching devices. In this way, the battery 110 over-discharge protection method can effectively protect the battery 110, extend its service life, and ensure the safe and stable operation of the energy storage system.

[0140] In one feasible implementation, refer to Figure 9 The step of controlling the opening and closing states of the first switching device QF+MX and the second switching device KT2 according to the over-discharge level of the battery 110 and / or the connection state of the transformer circuit 200 with the external power supply, and controlling the charging and discharging of the battery 110 according to the maximum discharge current of the battery 110 includes step S540, when the battery 110 is in the fourth level of over-discharge state, controlling the first switching device QF+MX and the second switching device KT2 to be in the open state, so as to stop the battery management circuit from continuing to consume the battery 110 power.

[0141] In this embodiment, when the battery 110 is in a level four over-discharge state, that is, when the voltage Ubat0 across the battery terminals is less than the fourth preset voltage threshold, the battery 110 reaches the over-discharge danger zone. Therefore, the battery 110 over-discharge prevention control device controls the first switching device QF+MX and the second switching device KT2 to be in the open state, that is, simultaneously disconnecting the power transmission channel between the battery 110 and the transformer circuit 200 and the power transmission channel between the battery 110 and the battery management circuit, so as to prevent the auxiliary power source in the transformer circuit 200 and the battery management circuit from still consuming the battery 110 power, causing the battery 110 to be over-discharged.

[0142] In this embodiment, the over-discharge level of battery 110 is determined by acquiring the SoC and the voltage Ubat0 across the battery terminals, and then the connection status of transformer circuit 200 with external power supply is acquired. The SoC of battery 110 is then adjusted based on the over-discharge level and / or the connection status of transformer circuit 200 with external power supply. The maximum discharge current of battery 110 is determined based on the adjusted SoC and a preset discharge cutoff SoC. Finally, the opening and closing states of the first switching device QF+MX and the second switching device KT2 are controlled based on the over-discharge level and / or the connection status of transformer circuit 200 with external power supply, and the charging and discharging of battery 110 is controlled based on the maximum discharge current. Thus, this application can provide step-by-step protection for battery 110 when its charge is low, either by disconnecting the discharge path of battery 110 or by replenishing the battery 110 with charge when conditions are met, thereby preventing over-discharge and improving the safety and reliability of battery 110.

[0143] This application also provides a battery 110 over-discharge protection control device, see reference. Figure 12 The battery 110 over-discharge protection control device includes: a memory 10, a processor 20, and a computer program stored on the memory 10 and executable on the processor 20, the computer program being configured to implement the steps of the battery 110 over-discharge protection control method.

[0144] In one feasible implementation, refer to Figure 13 The memory 10 includes a first memory 11 and a second memory 12, and the processor 20 includes a first processor 21 and a second processor 22. The first memory 11 and the first processor 21 are integrated in the first chip U1, and the second memory 12 and the second processor 22 are integrated in the second chip U2. The first chip U1 and the second chip U2 are communicatively connected.

[0145] The first chip U1 is used to acquire the SoC of battery 110 and the voltage Ubat0 across the battery terminals, and determine the over-discharge level of battery 110 based on the SoC and / or the voltage Ubat0. The second chip U2 is used to acquire the connection status of transformer circuit 200 with external power supply, adjust the SoC of battery 110 based on the over-discharge level of battery 110 and / or the connection status of transformer circuit 200 with external power supply, determine the maximum discharge current of battery 110 based on the adjusted SoC and preset discharge cutoff SoC, control the opening and closing states of the first switching device QF+MX and the second switching device KT2 based on the over-discharge level of battery 110 and / or the connection status of transformer circuit 200 with external power supply, and control the charging and discharging of battery 110 based on the maximum discharge current of battery 110. It is understood that the steps performed by the first chip U1 and the second chip U2 can be substituted for each other and implemented in another chip.

[0146] In this embodiment, by distributing the control and data processing functions of the battery 110 over-discharge protection control device across two chips, the system's reliability and processing speed can be improved. It is understood that the first chip U1 can employ BCU (Battery 110 Control Unit) technology, which is located in the energy storage circuit 100, specifically in the battery management circuit of the energy storage circuit 100. While acquiring the battery SoC, it can also perform real-time control of the battery 110, including battery 110 charging and discharging control, battery 110 status monitoring, etc. The second chip U2 can employ DSP (Digital Signal Processing) technology, which can quickly and accurately process the battery 110's discharge current data and adjust the discharge rate or control the charging process based on the battery 110's real-time status. Through this division of labor, the two chips can fully leverage their respective advantages, improving the overall performance of the battery 110 over-discharge protection control device. Of course, the specific types and models of the first chip U1 and the second chip U2 can be selected and optimized according to different application scenarios and technical requirements, and are not limited here.

[0147] The battery 110 over-discharge protection control device provided in this application can improve the safety and reliability of the battery 110. Compared with the prior art, the beneficial effects of the battery 110 over-discharge protection control device provided in this application are the same as the beneficial effects of the battery 110 over-discharge protection control method provided in the above embodiments, and will not be repeated here.

[0148] This application also provides an energy storage system, referenced Figure 14 The energy storage system includes:

[0149] Battery 110;

[0150] A battery management circuit is electrically connected to the battery 110;

[0151] A first switching device QF+MX, the first terminal of the first switching device QF+MX is connected to the battery 110, and the second terminal of the first switching device QF+MX is connected to the battery management circuit;

[0152] A transformer circuit 200, the first end of which is connected to the battery 110, and the second end of which is used to connect to an external power source;

[0153] The second switching device KT2 has its first terminal connected to the third terminal of the first switching device QF+MX, and its second terminal connected to the first terminal of the transformer circuit 200.

[0154] In this embodiment, the battery 110 is disposed in the energy storage circuit 100, specifically it can be a high-voltage battery 110, a lithium-ion battery 110, a lead-acid battery 110, etc. The number of batteries 110 can be configured as one or more according to actual energy storage needs. Optionally, the energy storage circuit 100 includes one or more battery packs 110 (first battery pack PACK1, second battery pack 110, ..., nth battery pack PACKn, where n is greater than or equal to), and the batteries 110 can be disposed in one or more battery packs 110. Each battery pack 110 also includes a battery detection unit (first battery detection unit BMU1BMU, second battery detection unit ..., nth battery detection unit BMUn, where n is greater than or equal to), the battery detection unit is used to monitor the voltage, current, temperature and other parameters of the battery 110, and transmit these parameters to the first chip U1 in real time. Through the monitoring of the battery detection unit, the changes in the battery charge, health status and potential safety hazards of the battery 110 can be obtained and detected, thereby providing a guarantee for the stable operation of the energy storage system.

[0155] In one feasible implementation, the first switching device QF+MX and the second switching device KT2 may specifically include a micro-break switch, a relay, a transistor, etc. Since the first terminal of the first switching device QF+MX is connected to the battery 110, the second terminal of the first switching device QF+MX is connected to the battery management circuit, the first terminal of the second switching device KT2 is connected to the third terminal of the first switching device QF+MX, and the second terminal of the second switching device KT2 is connected to the first terminal of the transformer circuit 200, that is, the battery 110 is connected to the power management circuit through the first switching device QF+MX, and the battery 110 is connected to the transformer circuit 200 through the first switching device QF+MX and the second switching device KT2. Through the first switching device QF+MX, the connection between the battery 110 and the energy storage circuit 100 or the battery management circuit can be disconnected when the battery 110 is too low, so as to prevent the auxiliary power source or the power management circuit in the transformer circuit 200 from continuing to work and continue to consume the battery 110, causing the battery 110 to be over-discharged. Furthermore, the first switching device QF+MX can quickly disconnect the battery 110 from the energy storage circuit 100 when the battery 110 malfunctions, preventing the fault from spreading to the entire energy storage system. The second switching device KT2 can disconnect the battery 110 from the transformer circuit 200 when the battery's charge is too low, thus preventing the battery 110 from continuing to discharge under the action of the transformer circuit 200. In this way, even if the battery management circuit or external auxiliary power source is still consuming a small amount of power, the over-discharge phenomenon of the battery 110 can be effectively controlled because the connection between the battery 110 and the external circuit has been disconnected. Moreover, when the battery 110's charge returns to a safe level, the second switching device KT2 can close again, restoring the normal charging and discharging function of the battery 110.

[0156] In one feasible implementation, the energy storage circuit 100 further includes a heating element 120 and a third switching device KT3. The heating element 120 is disposed on the battery 110, the first terminal of the third switching device KT3 is connected to the battery 110, and the second terminal of the third switching device KT3 is connected to the transformer circuit 200. In this embodiment, the second switching device KT2, the fourth switching device KT1, the third switching device KT3, and the first switching device QF+MX can be electronic switching components such as relays, transistors, MOSFETs, and IGBTs. In this embodiment, under low-temperature conditions, the internal resistance of the battery 110 increases, and its discharge capacity decreases. To ensure the normal operation of the battery 110 in low-temperature environments, the heating element 120 and the third switching device KT3 are introduced in this embodiment. When the ambient temperature is detected to be lower than a preset threshold, and the transformer circuit 200 is connected to the power grid and / or external power generation equipment, the third switching device KT3 closes, and the heating element 120 starts to work, providing the necessary heat to the battery 110, thereby keeping the battery 110 operating within a suitable temperature range. The heating element 120 can be a resistance wire, an electric heating film, or other suitable heating element.

[0157] In this embodiment, one end of the transformer circuit 200 is electrically connected to the energy storage circuit 100 via an external power line, and the other end of the transformer circuit 200 is used to connect to external power generation equipment and / or the power grid. The external power line can be a wire or cable connecting the transformer circuit 200 and the energy storage circuit 100 to achieve power transmission between them. It is understood that the external power generation equipment can be renewable energy equipment such as wind turbines, solar photovoltaic panels, and hydroelectric generators, or it can be traditional fossil fuel power generation equipment. The power grid can be the national power grid, local power grid, or an independent microgrid system. The external load can be household electrical equipment, industrial electrical equipment, commercial electrical equipment, etc. The transformer circuit 200 may include a first transformer circuit 210, a second transformer circuit 220, an inverter circuit 230, etc. The first transformer circuit 210 may include a bidirectional buck-boost circuit to realize bidirectional flow of electrical energy. That is, in energy storage mode, the voltage output by the external power generation equipment is converted into a voltage suitable for charging the battery 110 via the second transformer circuit 220, or the voltage of the power grid is converted into a voltage suitable for charging the battery 110 via the inverter circuit 230 to charge the battery 110 of the energy storage circuit 100. In discharge mode, the electrical energy stored in the battery 110 is converted into a bus voltage Ubus to supply power to external equipment, or the bus voltage Ubus is inverted into the voltage corresponding to the power grid via the inverter circuit 230 to store the electrical energy of the battery 110 into the power grid, thereby realizing the discharge of the battery 110 of the energy storage circuit 100.

[0158] In one feasible implementation, the transformer circuit 200 includes a first transformer circuit 210, a second transformer circuit 220, and an inverter circuit 230. The fourth switching device KT1 is disposed at the first terminal of the first transformer circuit 210. The first terminal of the first transformer circuit 210 is electrically connected to the energy storage circuit 100. The second terminal of the first transformer circuit 210 is connected to the first terminal of the second transformer circuit 220 and the first terminal of the inverter circuit 230, respectively. The second terminal of the second transformer circuit 220 is used to connect to an external power generation device, and the second terminal of the inverter circuit 230 is used to connect to the power grid.

[0159] In this embodiment, the first transformer circuit 210 includes an inductor L, a first capacitor CLbus, a second capacitor CHbus, a first switch S1, and a second switch S2 to form a bidirectional buck-boost circuit. This circuit controls the conduction state of either the first switch S1 or the second switch S2, thereby controlling the direction of energy flow in the first transformer circuit 210 and controlling the inductor L to store and release energy to the output terminal. This increases the output voltage, enabling the first transformer circuit 210 to operate in boost mode, or it controls the inductor L to release energy to the input terminal, decreasing the output voltage, enabling the first transformer circuit 210 to operate in buck mode. Optionally, a PWM control strategy can be used to adjust the conduction time of the first switch S1 and the second switch S2 to achieve precise voltage regulation and meet the needs of different application scenarios.

[0160] In this embodiment, the second transformer circuit 220 may include components such as a transformer, a rectifier bridge, and a filter capacitor, used to rectify and filter the voltage output from the external power generation equipment to ensure a stable DC voltage output to the first transformer circuit 210. The inverter circuit 230 may include components such as an inverter bridge, a filter inductor L, and a filter capacitor, used to convert the grid voltage into a voltage suitable for charging the battery 110, thereby charging the battery 110 of the energy storage circuit 100, or to invert the bus voltage Ubus into the grid voltage to store the energy of the battery 110 into the grid, thereby discharging the battery 110 of the energy storage circuit 100.

[0161] The energy storage system provided in this application can improve the safety and reliability of battery 110. Compared with the prior art, the beneficial effects of the energy storage system provided in this application are the same as those of the battery 110 over-discharge control method provided in the above embodiments, and will not be repeated here.

[0162] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A battery over-discharge prevention control method, applied to an energy storage system, characterized in that, The energy storage system includes: Battery; Battery management circuitry, electrically connected to the battery; A first switching device, wherein a first terminal of the first switching device is connected to the battery, and a second terminal of the first switching device is connected to the battery management circuit; A transformer circuit, wherein the first terminal of the transformer circuit is connected to the battery, and the second terminal of the transformer circuit is used to connect to an external power source; A second switching device, wherein a first terminal of the second switching device is connected to a third terminal of the first switching device, and a second terminal of the second switching device is connected to a first terminal of the transformer circuit; The battery over-discharge prevention control method includes: Obtain the battery's SoC and the voltage across the battery terminals, and determine the battery's over-discharge level based on the battery's SoC and / or the voltage across the battery terminals; Obtain the connection status between the transformer circuit and the external power supply; Adjust the battery's SoC according to the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply; The maximum discharge current of the battery is determined based on the adjusted SoC of the battery and the preset discharge cutoff SoC. Based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, the opening and closing states of the first and second switching devices are controlled, and the battery charging and discharging are controlled based on the battery's maximum discharge current.

2. The battery over-discharge control method as described in claim 1, characterized in that, The step of obtaining the battery's SoC and the voltage across the battery terminals, and determining the battery's over-discharge level based on the battery's SoC and / or the voltage across the battery terminals, includes: Obtain the battery's SoC, the voltage across the battery terminals, the preset SoC, the first preset voltage threshold, the second preset voltage threshold, the third preset voltage threshold, and the fourth preset voltage threshold; When the battery's SoC is lower than a preset SoC and the voltage across the battery is greater than a first preset voltage, or when the voltage across the battery is greater than the first preset voltage and less than a second preset voltage, the battery is determined to be in a first-level over-discharge state. When the voltage across the battery is greater than a third voltage threshold and less than a first preset voltage threshold, the battery is determined to be in a secondary over-discharge state. When the voltage across the battery is less than a third preset voltage threshold and greater than a fourth preset voltage threshold, the battery is determined to be in a level three over-discharge state. When the voltage across the battery is less than a fourth preset voltage threshold, the battery is determined to be in a level four over-discharge state. Among them, the first preset voltage threshold is less than the second preset voltage threshold, the third preset voltage threshold is less than the first preset voltage threshold, and the fourth preset voltage threshold is less than the third preset voltage threshold.

3. The battery over-discharge prevention control method as described in claim 1, characterized in that, The step of adjusting the battery's SoC based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply includes: When the battery is in a secondary over-discharge state, the SoC of the battery is calibrated to a preset discharge cutoff SoC; When the battery is in a three-stage over-discharge state and the transformer circuit is connected to an external power source, the SoC of the battery is assigned a preset SoC that is less than the preset discharge cutoff SoC.

4. The battery over-discharge prevention control method as described in claim 1, characterized in that, The step of determining the maximum discharge current of the battery based on the adjusted battery SoC and the preset discharge cutoff SoC includes: When the adjusted SoC of the battery is greater than or equal to the preset discharge cutoff SoC, the maximum discharge current of the battery is determined to be not less than the preset current threshold. When the battery's SoC is less than the preset discharge cutoff SoC, the maximum discharge current of the battery is determined to be less than the preset current threshold.

5. The battery over-discharge prevention control method as described in claim 1, characterized in that, The steps of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, include: When the battery is in a first-stage over-discharge state or a second-stage over-discharge state, the first and second switching devices are controlled to be in a closed state, and the discharge rate of the battery is adjusted based on the maximum discharge current of the battery.

6. The battery over-discharge prevention control method as described in claim 1, characterized in that, The steps of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, include: When the battery is in a three-stage over-discharge state and the transformer circuit is connected to an external power source, the first and second switching devices are controlled to be in a closed state, and when the maximum discharge current of the battery is less than a preset current threshold, the power from the external power source is output to the battery to charge the battery.

7. The battery over-discharge prevention control method as described in claim 1, characterized in that, The steps of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, include: When the battery is in a three-stage over-discharge state and the transformer circuit is not connected to an external power source, the first switching device is controlled to be in a closed state and the second switching device is controlled to be in an open state, so as to stop the battery from discharging.

8. The battery over-discharge control method as described in claim 1, characterized in that, The steps of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, include: When the battery is in a three-stage over-discharge state and the transformer circuit is not connected to an external power source, after the battery continues to discharge for a first preset time, the second switching device is controlled to be in an open state to stop the battery from continuing to discharge.

9. The battery over-discharge prevention control method as described in claim 1, characterized in that, The steps of controlling the opening and closing states of the first and second switching devices based on the battery's over-discharge level and / or the connection status of the transformer circuit with the external power supply, and controlling the battery charging and discharging based on the battery's maximum discharge current, include: When the battery is in a level 4 over-discharge state, both the first and second switching devices are turned off to stop the battery management circuit from continuing to consume battery power.

10. A battery over-discharge protection control device, characterized in that, The battery over-discharge protection control device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the battery over-discharge protection control method as described in any one of claims 1 to 9.

11. An energy storage system, characterized in that, The energy storage system includes: Battery; A transformer circuit, wherein the first terminal of the transformer circuit is connected to the battery, and the second terminal of the transformer circuit is used to connect to an external power source; The energy storage system uses the battery over-discharge control method as described in any one of claims 1 to 9, or the energy storage system includes the battery over-discharge control device as described in claim 10.

Images