Battery pack capacity checking control method, energy storage system and storage medium

Abstract

The invention relates to the technical field of charging and discharging, in particular to a battery pack capacity checking control method, an energy storage system and a storage medium. The battery pack capacity checking control method comprises the steps that when a battery pack is powered on, a bidirectional DC / DC conversion module is controlled to pre-charge a load connected to a direct-current bus in parallel, and when the difference value between the voltage of the direct-current bus and the voltage output by a battery pack reaches a preset value, a power switch is closed; and in response to the capacity-checking discharge instruction, controlling the bidirectional DC / DC conversion module to enable the voltage output by the battery pack to be higher than the voltage of the DC bus, and performing capacity-checking discharge on the load by using the battery pack. The participation of electronic components in the pre-charging circuit and the capacity checking circuit is reduced, and the reliability of a hardware integrated circuit is improved.

Description

Technical Field

[0001] This invention relates to the field of charge and discharge technology, and in particular to a battery pack capacity control method, an energy storage system, and a storage medium. Background Technology

[0002] If backup batteries in current communication base stations experience insufficient backup power duration or inability to charge / discharge during long-term use, it may be due to inaccurate battery charge rating, leading to incorrect SOC / SOH estimations, or over / under voltage conditions. Undercharging, overcharging, over-discharging, and excessively high ambient temperatures can all degrade battery performance. Performing a full-capacity discharge test can objectively and accurately measure the battery's true capacity. Furthermore, proper charging and discharging can extend battery life and ensure the reliability of the DC system.

[0003] Backup batteries for communication base stations are typically manually operated on-site, with a host computer controlling the battery's capacity discharge. For example... Figure 1 As shown, in the current high-voltage architecture of the backup battery, K1 is the charging MOS, K2 is the discharging MOS, K3 is the pre-charge MOS, and R is the pre-charge resistor. When the system is powered on, K1 is closed first, then K3 is closed. R2 and K3 form the pre-charge branch. The battery uses this pre-charge branch to pre-charge the load. After the pre-charge is completed, K2 is closed and K3 is opened. The battery uses the main charging circuit to discharge the load.

[0004] Because existing pre-charge and core capacitance circuits contain many electronic components, they are prone to failure, which reduces the reliability of the hardware circuits. Summary of the Invention

[0005] The purpose of this invention is to provide a battery pack capacity control method, an energy storage system, and a storage medium. It utilizes a bidirectional DC / DC conversion module to control pre-charge and capacity control, reducing the number of electronic components in the circuit and thus improving the reliability of the hardware integrated circuit.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A battery pack includes: a battery pack, a bidirectional DC / DC converter module, and a power switch; The battery pack is connected to the DC bus via the bidirectional DC / DC conversion module, and the power switch is located between the bidirectional DC / DC conversion module and the DC bus.

[0007] A battery pack capacity control method, comprising: When the battery pack is powered on, the bidirectional DC / DC conversion module is controlled to precharge the load connected in parallel on the DC bus. When the difference between the voltage of the DC bus and the voltage output by the battery pack reaches a preset value, the power switch is closed. In response to the full capacity discharge command, the bidirectional DC / DC conversion module is controlled to make the voltage output by the battery pack higher than the voltage of the DC bus, and the battery pack is used to perform full capacity discharge on the load.

[0008] Furthermore, the battery pack also includes: a battery management system (BMS) unit; The battery management system (BMS) unit is used to control the bidirectional DC / DC conversion module and to control the power switch.

[0009] Furthermore, the process of the battery pack performing a full-capacity discharge on the load includes: Real-time monitoring of the battery pack's discharge current, individual cell voltage, and discharge time; Determine whether the lowest single cell voltage of the battery pack has reached the full discharge cutoff voltage. If so, control the bidirectional DC / DC conversion module to stop the battery pack from discharging.

[0010] Furthermore, before the battery pack performs full capacity discharge on the load, it also includes: Determine whether the current voltage value of the battery pack is the full charge voltage value; If not, in response to the charging command, the bidirectional DC / DC converter module is controlled to perform constant current charging on the battery pack.

[0011] Furthermore, the process of controlling the bidirectional DC / DC conversion module to perform constant current charging of the battery pack includes: Real-time monitoring of the battery pack's charging current, individual cell voltage, and charging time; Determine whether the highest single cell voltage of the battery pack has reached the full charge cutoff voltage. If so, control the bidirectional DC / DC conversion module to stop charging the battery pack.

[0012] Furthermore, the charging current of the battery pack is the difference between the maximum allowable charging current and the load current; The maximum allowable charging current is the minimum value among the maximum allowable charging current of the cable, the maximum allowable charging current of the battery cell, and the maximum output current of the switching power supply.

[0013] Furthermore, the total discharge amount is calculated based on the discharge current and the discharge time, and the total discharge amount is used as the rated capacity of the battery pack.

[0014] An energy storage system comprising a battery pack; The battery pack includes: a battery pack, a bidirectional DC / DC converter module, and a power switch; The battery pack is connected to the DC bus via the bidirectional DC / DC conversion module, and the power switch is located between the bidirectional DC / DC conversion module and the DC bus; When the battery pack is powered on, the bidirectional DC / DC conversion module is controlled to precharge the load connected in parallel on the DC bus. When the difference between the voltage of the DC bus and the voltage output by the battery pack reaches a preset value, the power switch is closed. After the power switch is closed, the bidirectional DC / DC conversion module is used to control the charging of the battery pack or the discharging of the load.

[0015] Furthermore, the battery pack also includes: a battery management system (BMS) unit; The battery management system (BMS) unit is used to control the bidirectional DC / DC conversion module and to control the power switch.

[0016] Based on the same inventive concept, the present invention also provides a computer storage medium storing computer-executable instructions, which, when executed, implement the aforementioned battery pack capacity control method.

[0017] The technical effects and advantages of this invention are as follows: (1) During the power-on process of the battery pack, the load is pre-charged using a bidirectional DC / DC conversion module to avoid large current surges. After the pre-charging is completed, the power switch is closed. The bidirectional DC / DC conversion module and the power switch constitute a core capacity charging and discharging circuit. (2) By controlling the pre-charge and core capacity process through the bidirectional DC / DC conversion module, the involvement of electronic devices in the circuit is reduced, and the reliability of the hardware integrated circuit is improved.

[0018] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a pre-charging circuit in the existing technology; Figure 2This is a schematic diagram of the connection between the battery pack and the load provided in an embodiment of the present invention; Figure 3 This is a flowchart of a battery pack capacity control method provided in an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The first embodiment of the present invention discloses a battery pack, such as Figure 2 As shown, the battery pack includes a battery bank, a bidirectional DC / DC converter module, and a power switch S3. When the battery pack and the load are connected in parallel with the DC bus, the battery bank is connected to the DC bus through the bidirectional DC / DC converter module, and the power switch S3 is located between the bidirectional DC / DC converter module and the DC bus. When the power switch S3 is closed, the battery bank is connected to the high-voltage circuit of the DC bus, and the battery pack is powered on.

[0023] The battery pack is a battery unit composed of multiple individual battery cells connected in series.

[0024] The bidirectional DC / DC conversion module can be understood as a bidirectional DC / DC converter. The core components of the bidirectional DC / DC converter include power switching devices, control modules, filter capacitors, and inductors, which can realize the step-up / step-down conversion between direct current (DC) and the bidirectional flow of DC current.

[0025] Preferably, the battery pack further includes a battery management system (BMS) unit. The BMS unit controls the bidirectional DC / DC converter module and controls the on / off state of the power switch S3. The BMS unit can manage the charging and discharging process of the battery pack through the bidirectional DC / DC converter module.

[0026] In this embodiment of the invention, the battery pack, bidirectional DC / DC conversion module, power switch S3, and battery management system (BMS) unit are integrated into the battery pack. The battery management system (BMS) unit controls the bidirectional DC / DC conversion module and power switch S3 to realize battery pack charging, discharging, load pre-charging, and capacity management. The circuit integration is high, and the battery pack is easy to implement intelligent management.

[0027] The second embodiment of the present invention discloses a battery pack capacity control method, wherein the battery pack is the same as the battery pack in the first embodiment, and the battery pack integrates a battery pack, a bidirectional DC / DC conversion module, a power switch S3 and a battery management system (BMS) unit.

[0028] When the battery management system (BMS) controls the power switch S3 to close, the battery pack is connected to the high-voltage circuit of the DC bus, and the battery pack is powered on.

[0029] Typically, the 220V AC power generated by the municipal power grid is converted to 48V DC power by an AC / DC module and then connected to the DC bus. The load and battery pack are connected in parallel to the DC bus and powered by the DC bus. Preferably, the load circuit may include important equipment (primary equipment) and secondary equipment (secondary devices). The battery management system (BMS) unit is also used to control the switch S1 of the important equipment and the switch S2 of the secondary equipment.

[0030] like Figure 3 As shown, the battery pack capacity control method provided in this embodiment of the invention includes the following steps: Step 1: When the battery pack is powered on, control the bidirectional DC / DC conversion module to precharge the load connected in parallel on the DC bus. When the difference between the voltage of the DC bus and the voltage output by the battery pack reaches a preset value, close the power switch S3. Step 2: In response to the full capacity discharge command, control the bidirectional DC / DC conversion module to make the voltage output by the battery pack higher than the voltage of the DC bus, and use the battery pack to perform full capacity discharge on the load.

[0031] The power-on process of the battery pack can be divided into two situations: when the mains power grid fails, causing the voltage of the DC bus to be zero, and when the DC bus is powered normally.

[0032] In the first scenario, when the mains power grid fails, causing both the DC bus voltage and the load's input voltage to be zero, a large current will be instantly generated if the battery is directly connected to the load. This surge of current can damage components in the load (such as capacitors, IGBTs, and MOSFETs). Therefore, in this embodiment, the output voltage of the bidirectional DC / DC converter module, i.e., the DC bus voltage, is adjusted to gradually increase and approach the voltage of the battery pack. During this process, the battery pack pre-charges the load through the bidirectional DC / DC converter module, gradually increasing the load's capacitor voltage. When the difference between the DC bus voltage and the total voltage of the battery pack reaches a preset value, the power switch S3 is closed, completing the pre-charging of the load.

[0033] Preferably, when the preset pre-charge time is reached (e.g., the pre-charge time is 6s), or when the voltage of the DC bus is adjusted until the absolute value of the difference between the DC bus voltage and the battery pack output voltage is less than or equal to 3V, the power switch S3 is closed.

[0034] In the second scenario, when the DC bus is supplying power normally, since the voltage of the load capacitor is the same as the voltage of the DC bus (48V), during the process of controlling the bidirectional DC / DC conversion module to precharge the load connected in parallel to the DC bus, the float charge voltage of the battery pack in the battery pack is not much different from the voltage of the DC bus. Therefore, the precharging process of the battery pack for the load is very short, taking only tens or hundreds of milliseconds.

[0035] In step two, when the battery management system (BMS) detects that the cumulative charge / discharge capacity of the battery pack reaches five times its rated capacity, or when the cumulative operating time of the battery pack reaches a preset duration, the server sends an automatic capacity verification command to the BMS. Optionally, the BMS receives the automatic capacity verification command via an RS485 interface. In practical applications, the automatic capacity verification command is typically sent between 0:00 and 1:00 AM, because deep discharge of the battery pack takes approximately 3 hours, and charging takes approximately 2 hours. Completing the capacity verification process late at night reduces the risk of insufficient backup power.

[0036] According to an embodiment of the present invention, the battery management system (BMS) unit, in response to a capacity discharge command, controls the bidirectional DC / DC converter module to make the voltage output by the battery pack higher than the voltage of the DC bus, thereby discharging the battery pack to the load. For example, in a photovoltaic project, the voltage output by the bidirectional DC / DC converter module is controlled to rise to [DC bus voltage value + (0.5~2)]V.

[0037] The process of the battery pack performing capacity discharge on the load in step two specifically includes: real-time monitoring of the discharge current, individual cell voltage, and discharge time of the battery pack; determining whether the lowest individual cell voltage of the battery pack has reached the full discharge cutoff voltage; if so, controlling the bidirectional DC / DC conversion module to stop the battery pack from discharging.

[0038] Furthermore, the total discharge amount is calculated based on the discharge current and the discharge time, and the total discharge amount is used as the rated capacity of the battery pack.

[0039] According to a preferred embodiment of the present invention, if it is necessary to determine the current remaining power of the battery pack, the battery management system (BMS) unit uses a bidirectional DC / DC converter module to control the battery pack to discharge to the load. The BMS unit monitors the discharge current, individual cell voltage, and discharge time of the battery pack in real time, calculates a first discharge amount based on the discharge current and discharge time during the discharge process, and regards the first discharge amount as the remaining power of the battery pack.

[0040] The nuclear discharge process can be described as follows: In the initial stage of discharge, the discharge current is stable due to the high initial voltage of the battery pack; as the battery pack's charge decreases, its output voltage gradually decreases, and the bidirectional DC / DC conversion module is used to adjust the battery pack's output voltage to increase. Since the load power is constant, the discharge current of the battery pack increases; when the remaining charge of the battery pack drops to a certain value, the battery pack's output power cannot meet the load's power requirements, so the battery pack outputs at maximum power, resulting in a decrease in the discharge current; the discharge stops when the lowest single cell voltage of the battery pack reaches the full discharge cutoff voltage.

[0041] According to another preferred embodiment of the present invention, if it is necessary to verify the rated capacity of the battery pack, a recharging step is further included before the battery pack performs a deep capacity discharge to the load.

[0042] The charging step includes: determining whether the current voltage value of the battery pack is the full charge voltage value; if not, in response to the charging command, controlling the bidirectional DC / DC conversion module to perform constant current charging on the battery pack until the battery pack reaches a full charge state.

[0043] The process of constant current charging of the battery pack specifically includes: real-time monitoring of the charging current, voltage of each individual cell, and charging time of the battery pack; determining whether the highest individual cell voltage of the battery pack has reached the full charge cutoff voltage; if so, controlling the bidirectional DC / DC conversion module to stop charging the battery pack.

[0044] In this embodiment of the invention, the charging current of the battery pack is the difference between the maximum allowable charging current and the load current. The maximum allowable charging current is the minimum value among the maximum allowable charging current of the cable, the maximum allowable charging current of the battery cell, and the maximum output current of the switching power supply. The maximum allowable charging current of the cable and the maximum allowable charging current of the battery cell are calculated or obtained from tables based on the cable characteristics and battery cell characteristics under different voltage, temperature, and other objective conditions. The maximum output current of the switching power supply is the maximum current output by the AC / DC module.

[0045] According to the above method, when the battery pack is not fully charged, the battery management system (BMS) controls the bidirectional DC / DC converter to perform constant current charging on the battery pack until the voltage of the highest single cell in the battery pack reaches the full charge cutoff voltage. At this point, the battery pack is considered to be fully charged. Afterward, the BMS responds to the capacity discharge command and uses the bidirectional DC / DC converter to control the battery pack to perform deep capacity discharge. It monitors the discharge current, the voltage of each single cell, and the discharge time in real time. Based on the discharge current and discharge time during the discharge process, it calculates a second discharge amount, which is considered the rated capacity of the battery pack. After deep discharge, the battery pack is charged using the above-described recharging steps to maintain a standby power state.

[0046] According to an embodiment of the present invention, during the process of the power switch S3 going from open to closed, the battery pack is powered on, and its battery pack uses the bidirectional DC / DC conversion module to precharge the load to avoid large current surges. After the power switch is closed, the bidirectional DC / DC conversion module and the power switch constitute a capacity-accumulating circuit. The use of the bidirectional DC / DC conversion module to control the precharging and capacity-accumulating processes reduces the involvement of electronic components in the circuit and improves the reliability of the hardware integrated circuit.

[0047] The third embodiment of the present invention discloses an energy storage system, which includes a battery pack. The battery pack is connected in parallel with a DC bus for energy storage and backup power. When the mains power grid fails, the battery pack charges the load connected in parallel with the DC bus.

[0048] The battery pack is the battery pack in the first embodiment, which integrates a battery pack, a bidirectional DC / DC converter module, a power switch S3, and a battery management system (BMS) unit. The battery pack is connected to the DC bus via the bidirectional DC / DC converter module, and the power switch S3 is located between the bidirectional DC / DC converter module and the DC bus.

[0049] When the battery pack is powered on, the battery management system (BMS) controls the bidirectional DC / DC converter module to precharge the load. When the difference between the voltage of the DC bus and the voltage output by the battery pack reaches a preset value, the BMS controls the power switch S3 to close, the precharging process ends, the battery pack is connected to the high-voltage circuit of the DC bus, and the battery pack is powered on.

[0050] After the power switch S3 is closed, the battery management system (BMS) unit controls the bidirectional DC / DC converter module to charge the battery pack or uses the battery pack to discharge the load.

[0051] Regarding the battery pack and its charging and discharging process in the above embodiments, the specific way in which each unit module performs its operation has been described in detail in the battery pack capacity control method in the second embodiment, and will not be elaborated here.

[0052] Based on the same inventive concept, embodiments of the present invention also provide a computer storage medium storing computer-executable instructions, which, when executed, implement the aforementioned battery pack capacity control method.

[0053] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0054] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, the functional modules in the various embodiments of this invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0055] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0056] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0057] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not described in detail in a particular embodiment can be found in the relevant descriptions of other embodiments. Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the capacity of a battery pack, characterized in that, The battery pack includes: a battery pack, a bidirectional DC / DC converter module, and a power switch; The battery pack is connected to the DC bus via the bidirectional DC / DC conversion module, and the power switch is located between the bidirectional DC / DC conversion module and the DC bus; The battery pack capacity control method includes: When the battery pack is powered on, the bidirectional DC / DC conversion module is controlled to precharge the load connected in parallel on the DC bus. When the difference between the voltage of the DC bus and the voltage output by the battery pack reaches a preset value, the power switch is closed. In response to the full capacity discharge command, the bidirectional DC / DC conversion module is controlled to make the voltage output by the battery pack higher than the voltage of the DC bus, and the battery pack is used to perform full capacity discharge on the load.

2. The battery pack capacity control method according to claim 1, characterized in that, The battery pack also includes: a battery management system (BMS) unit; The battery management system (BMS) unit is used to control the bidirectional DC / DC conversion module and to control the power switch.

3. The battery pack capacity control method according to claim 1, characterized in that, The process of the battery pack performing a full-capacity discharge on the load includes: Real-time monitoring of the battery pack's discharge current, individual cell voltage, and discharge time; Determine whether the lowest single cell voltage of the battery pack has reached the full discharge cutoff voltage. If so, control the bidirectional DC / DC conversion module to stop the battery pack from discharging.

4. The battery pack capacity control method according to claim 3, characterized in that, Before the battery pack performs full capacity discharge on the load, it further includes: Determine whether the current voltage value of the battery pack is the full charge voltage value; If not, in response to the charging command, the bidirectional DC / DC converter module is controlled to perform constant current charging on the battery pack.

5. The battery pack capacity control method according to claim 4, characterized in that, The process of controlling the bidirectional DC / DC conversion module to perform constant current charging of the battery pack includes: Real-time monitoring of the battery pack's charging current, individual cell voltage, and charging time; Determine whether the highest single cell voltage of the battery pack has reached the full charge cutoff voltage. If so, control the bidirectional DC / DC conversion module to stop charging the battery pack.

6. The battery pack capacity control method according to claim 5, characterized in that, The charging current of the battery pack is the difference between the maximum allowable charging current and the load current; The maximum allowable charging current is the minimum value among the maximum allowable charging current of the cable, the maximum allowable charging current of the battery cell, and the maximum output current of the switching power supply.

7. The battery pack capacity control method according to any one of claims 3 to 6, characterized in that, The total discharge amount is calculated based on the discharge current and the discharge time, and the total discharge amount is used as the rated capacity of the battery pack.

8. An energy storage system, characterized in that, The energy storage system includes a battery pack; The battery pack includes: a battery pack, a bidirectional DC / DC converter module, and a power switch; The battery pack is connected to the DC bus via the bidirectional DC / DC conversion module, and the power switch is located between the bidirectional DC / DC conversion module and the DC bus; When the battery pack is powered on, the bidirectional DC / DC conversion module is controlled to precharge the load connected in parallel on the DC bus. When the difference between the voltage of the DC bus and the voltage output by the battery pack reaches a preset value, the power switch is closed. After the power switch is closed, the bidirectional DC / DC conversion module is used to control the charging of the battery pack or the discharging of the load.

9. The energy storage system according to claim 8, characterized in that, The battery pack also includes: a battery management system (BMS) unit; The battery management system (BMS) unit is used to control the bidirectional DC / DC conversion module and to control the power switch.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed, implement the battery pack capacity control method according to any one of claims 1-7.

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