Lithium battery system control method and device, controller and lithium battery system

Abstract

The invention provides a control method and device of a lithium battery system, a controller and the lithium battery system. According to the method, sampling points are arranged on the charging system side of the protection switch and the lithium battery module side of the output relay, and the closing time of the output relay can be judged through the effective voltage difference between the charging system side and the lithium battery module side, so that the state of the protection switch is ignored; the problem that impact current is generated on a device when an output relay is closed due to the influence of disconnection of a protection switch is avoided, the relay is closed only after the voltage of the lithium battery module actively approaches the voltage of a charging system through boost regulation, the risk of misoperation caused by unreasonable setting of sampling points is thoroughly eliminated, and the reliability of the device is improved. The current impact in the closing process is inhibited from the source, and the key foundation is laid for safe and reliable operation of the whole lithium battery system.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a control method, device, controller, and lithium battery system for a lithium battery system. Background Technology

[0002] With the maturity of lithium battery technology, lithium battery systems are increasingly widely used in UPS (Uninterruptible Power Supply) backup power and other fields. The reliability of its charging and discharging process directly determines the stability and safety of the entire power supply system. Currently, lithium battery modules need to be boosted by bidirectional DC / DC power modules to adapt to the UPS DC bus voltage, and then modularly connected in parallel to meet the configuration requirements of UPS with different power ratings. To ensure charging and discharging safety, existing lithium battery systems have adopted designs such as full isolation and automatic isolation of module faults. However, in actual UPS operation, when the output electrolytic capacitor is depleted after the system undervoltage protection, or when there is a large voltage difference between the UPS charging voltage and the high-voltage side of the lithium battery module, the instantaneous inrush current can easily cause the output fuse to blow, triggering the module to enter the protection state, which seriously affects the continuous operation capability of the system.

[0003] Existing lithium battery system charging and discharging control schemes determine the relay's closed state by identifying sampling points on both sides of the output relay. However, they cannot accurately determine the optimal timing for the output relay to engage. This results in frequent fuse blowouts and module protection failures caused by inrush currents when the lithium battery system is charged and discharged in conjunction with a UPS, severely restricting the reliability of the lithium battery system's charging and discharging. Summary of the Invention

[0004] This invention provides a control method, device, controller, and lithium battery system for a lithium battery system, in order to solve the problem of poor charging and discharging reliability of lithium battery systems in the prior art.

[0005] In a first aspect, embodiments of the present invention provide a control method for a lithium battery system, the lithium battery system including a protection switch, at least one lithium battery module and an output relay corresponding to each lithium battery module; the first end of the protection switch is used to connect to a charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit. The method includes: The voltage values ​​of the first sampling point and the second sampling point in the lithium battery system are collected; wherein, the first sampling point is located on the first end side of the protection switch; and the second sampling point is located on the second end side of each output relay. The closing timing of the output relay is determined based on the voltage values ​​of the first sampling point and the second sampling point.

[0006] In one possible implementation, determining the closing timing of the output relay based on the voltage values ​​of the first sampling point and the second sampling point includes: The voltage of the target lithium battery module is boosted according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then the target output relay is closed. The target lithium battery module can be any lithium battery module; the target output relay is the output relay corresponding to the target lithium battery module.

[0007] In one possible implementation, the step of controlling the target lithium battery module to boost voltage based on the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then closing the target output relay, includes: The operating condition of the charging system is determined based on the voltage value at the first sampling point; the operating condition includes a slow-start operating condition and a stable operating condition. If the charging system is in a slow start-up mode, the target lithium battery module is controlled to boost voltage according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the first preset voltage difference, and the target output relay is closed. If the charging system is in a stable operating condition, the target lithium battery module is controlled to boost voltage according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the second preset voltage difference, and the target output relay is closed. The first preset voltage difference is greater than the second preset voltage difference.

[0008] In one possible implementation, determining the operating condition of the charging system based on the rate of change of the voltage value at the first sampling point includes: If the voltage value at the first sampling point continues to increase within a first preset time period and the rate of change of the voltage value at the first sampling point is less than a preset rate of change threshold, then the charging system is determined to be in a slow start-up state; otherwise, the charging system is determined to be in a stable state.

[0009] In one possible implementation, the method further includes: Collect the voltage value at the third sampling point; the third sampling point is located on the first terminal side of any output relay. By comparing the voltage value of the first sampling point with the voltage value of the third sampling point, if the difference between the voltage value of the first sampling point and the voltage value of the third sampling point is greater than a third preset voltage difference, a first reminder message is generated; the first reminder message is used to prompt the user not to close the protection switch.

[0010] Secondly, embodiments of the present invention provide a control device for a lithium battery system, the lithium battery system including a protection switch, at least one lithium battery module and an output relay corresponding to each lithium battery module; the first end of the protection switch is used to connect to a charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit. The device includes: A sampling module is used to collect the voltage values ​​of a first sampling point and a second sampling point in the lithium battery system; wherein, the first sampling point is located on the first end side of the protection switch; and the second sampling point is located on the second end side of each output relay. The relay closing timing determination module is used to determine the closing timing of the output relay based on the voltage value of the first sampling point and the voltage value of the second sampling point.

[0011] Thirdly, embodiments of the present invention provide a controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method as described in any possible implementation of the first aspect above.

[0012] Fourthly, embodiments of the present invention provide a lithium battery system, including: a controller as described in the third aspect, a protection switch, at least one lithium battery module, and an output relay corresponding to each lithium battery module; the first end of the protection switch is used to connect to a charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit. The controller is used to execute the control method of the lithium battery system as described in the first aspect.

[0013] This invention provides a control method for a lithium battery system. By setting sampling points on the charging system side of the protection switch and the lithium battery module side of the output relay, the closing timing of the output relay can be determined by the effective voltage difference between the charging system side and the lithium battery module side. This ignores the state of the protection switch and avoids the problem of inrush current to the device when the output relay closes due to the influence of the protection switch being open. It ensures that the relay is closed only after the lithium battery module voltage actively approaches the charging system voltage through boost regulation, completely eliminating the risk of malfunction caused by unreasonable sampling point settings. This suppresses the current surge during the closing process from the source and lays the most critical foundation for the safe and reliable operation of the entire lithium battery system. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0015] Figure 1 This is a schematic diagram of the structure of the lithium battery system provided in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the implementation of the control method for a lithium battery system provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the control device for the lithium battery system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the controller provided in an embodiment of the present invention. Detailed Implementation

[0016] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the structure of a lithium battery system provided in an embodiment of the present invention. Figure 1As shown, the lithium battery system includes a protection switch and at least one lithium battery module; the lithium battery module includes output relays K1 (K1-1, K1-2) and lithium battery units; the first end of the protection switch is used to connect to the charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit.

[0019] In this embodiment, the lithium battery system is typically presented in the form of a lithium battery system cabinet, which integrates a protection switch, at least one lithium battery module, and a system cabinet terminal block. Each lithium battery module includes an output relay, a lithium battery unit, and a battery pack management unit (PBMU). The lithium battery unit includes a lithium battery pack and a bidirectional DC / DC converter. The core function of the lithium battery module is to perform the storage and conversion of electrical energy.

[0020] The first terminal of the protection switch is connected to the positive output terminal of the charging system, and the negative terminal of the first terminal of the protection switch is connected to the negative output terminal of the charging system. The positive terminal of the second terminal of the protection switch is connected to multiple first terminals in the wiring block of the system cabinet, and the negative terminal of the second terminal of the protection switch is connected to multiple second terminals in the wiring block of the system cabinet. The first and second terminals can be any two terminals in the wiring block of the system cabinet. Then, each first terminal is connected to the first terminal of the output relay corresponding to each lithium battery module, and each second terminal is connected to the negative terminal of each lithium battery unit. The second terminal of each output relay is connected to the positive terminal of its corresponding lithium battery unit.

[0021] In addition to the components mentioned above, a lithium battery system also includes a System Battery Management Unit (SBMU) for controlling the operation of the entire lithium battery system.

[0022] Specifically, the charging system mentioned in this embodiment is usually a UPS uninterruptible power supply. When the mains power fails, the lithium battery module can supply power to the charging system. When the lithium battery module is fully discharged, it can also be charged through the charging system.

[0023] The protective switch serves as the main switch between the lithium battery system and the external charging system. Users can manually close the protective switch, which automatically disconnects the circuit when the current exceeds a predetermined value or a short circuit occurs. The protective switch can be either an air switch or a circuit breaker. It should be noted that the second terminal of the protective switch is connected to each output relay only through the system terminal block; no other components are included.

[0024] Output relays are used to control the on / off state of their respective branches. One relay corresponds to each lithium battery module, responsible for connecting or disconnecting that module from the system's DC bus. The system terminal block combines the charging and discharging signals from multiple lithium battery modules and connects them to the charging system via a protection switch.

[0025] Currently, existing lithium battery system charging and discharging control schemes typically determine the closing timing of the output relay by identifying the voltage difference between sampling points on both sides of the output relay. However, when the lithium battery module is not started and the charging system is running stably, if the protection switch is open, the voltage values ​​on both sides of the output relay can be detected as zero through the two sampling points. The output relay is closed because the voltage difference between the two sampling points is less than a certain value. However, if the user manually closes the protection switch after the output relay is closed, the sudden DC voltage on the charging module side will cause a large current to rush into the output electrolytic capacitor inside the lithium battery module, causing the output fuse of the lithium battery module to blow instantly.

[0026] To avoid the above problems, this embodiment provides a control method for a lithium battery system, see [link to relevant documentation]. Figure 2 This document illustrates a flowchart of the control method for a lithium battery system provided in an embodiment of the present invention. The executing entity of this method can be the controller of the lithium battery system. Specifically, it can be a system battery management unit (SBMU) or a battery pack management unit (PBMU), and its implementation process is detailed below: S101: Collect the voltage values ​​of the first sampling point U1 and the second sampling point U2 in the lithium battery system; wherein, the first sampling point U1 is located on the first end side of the protection switch; and the second sampling point U2 is located on the second end side of each output relay.

[0027] In this embodiment, the first sampling point is located at the input terminal of the protection switch and is directly connected to the external charging system. It can be located on either the positive or negative connection line between the protection switch and the charging system. The charging and discharging voltage of the charging system can be collected through the first sampling point U1.

[0028] The second sampling point U2 is located on the second terminal side of the output relay. Electrically, this sampling point is located at the output terminal of the output relay and connected to the high-voltage output terminal of the DC / DC converter of the lithium battery module. It can be set on either the positive or negative connection line between the output relay and the DC / DC converter. The second sampling point U2 is used to collect the actual charging and discharging voltage of the lithium battery module.

[0029] Specifically, voltage sensors are installed at the first sampling point U1 and the second sampling point U2 respectively. The voltage sensor at the first sampling point U1 is connected to the system battery management unit, and the voltage sensor at the second sampling point U2 is connected to the battery pack management unit of the corresponding lithium battery module. The system battery management unit obtains the voltage value sent by the voltage sensor at the first sampling point, and the battery pack management unit obtains the voltage value sent by the voltage sensor at the second sampling point.

[0030] S102: Determine the closing timing of the output relay based on the voltage value of the first sampling point and the voltage value of the second sampling point.

[0031] In this embodiment, when the executing entity is the system battery management unit, the system battery management unit obtains the voltage value of the first sampling point and the voltage value of the second sampling point corresponding to each lithium battery module, and determines whether the output relay of the corresponding lithium battery module can be closed based on the voltage value of the first sampling point and the voltage value of the second sampling point corresponding to each lithium battery module.

[0032] Specifically, after a lithium battery module meets the conditions for other components to be integrated into the lithium battery system, the system battery management unit will, for each lithium battery module, perform the following operations: if the difference between the voltage values ​​at the first sampling point and the second sampling point is greater than or equal to a preset voltage difference, then the operation of closing the output relay of that lithium battery module will not be executed; if the difference between the voltage values ​​at the first sampling point and the second sampling point is less than the preset voltage difference, then the operation of closing the output relay of that lithium battery module will be executed.

[0033] Specifically, when the system management unit detects that the voltage difference between the first sampling point and the second sampling point is less than the preset voltage difference, it sends a relay closing command to the battery pack management unit of the corresponding lithium battery module. The battery pack management unit controls its output relay to close based on the received relay closing command.

[0034] As another specific implementation, to reduce the computational load of the system battery management unit, the main execution entity in this embodiment can be the battery pack management unit. That is, the system battery management unit sends the voltage value of the first sampling point to each battery pack management unit. Each battery pack management unit can determine the closing timing of its output relay based on the difference between the voltage value of the first sampling point and the voltage value of the second sampling point. The following explanation mainly uses the battery pack management unit as the execution entity. It can be understood that the control methods of the lithium battery system provided in the subsequent embodiments can all be executed in the system battery management unit.

[0035] Specifically, in traditional lithium battery systems, inrush current often occurs due to a voltage difference between the high-voltage side and the lithium battery module side, causing a sudden surge of current as the electronic components connected in series (such as electrolytic capacitors, resistors, and inductors) charge instantaneously. However, in this embodiment, there are no electronic components that need to charge or discharge between the protection switch and the output relay; it is merely a conductive path connected by a copper busbar. Therefore, there is no sudden surge of current due to charging of electronic components caused by a voltage difference. Even if a certain voltage difference exists between the second terminal of the protection switch and the first terminal of the output relay at the moment the output relay closes, due to the lack of electronic components for charge storage or energy conversion, the voltage difference will only manifest as a smooth transition of potential and will not form a destructive inrush current. This fundamentally avoids the risks of fuse blowing and module protection in traditional solutions.

[0036] Meanwhile, the first sampling point is located on the first end of the protection switch, enabling direct and real-time acquisition of the original charging and discharging voltage of the charging system. This is unaffected by the on / off state of the protection switch or the operation of the output relay, providing a precise and stable target reference for the boost control of the lithium battery module. The lithium battery module gradually boosts its voltage based on this sampling point until the voltage difference with its second sampling point meets a preset voltage difference, at which point it closes the output relay. This further ensures voltage matching at the moment of closure. Even if a small residual voltage difference exists, it will not be converted into an inrush current due to the lack of energy accumulation from intermediate electronic components.

[0037] As can be seen from the above embodiments, this embodiment, by setting sampling points on the charging system side of the protection switch and the lithium battery module side of the output relay, can determine the closing timing of the output relay through the effective voltage difference between the charging system side and the lithium battery module side. This ignores the state of the protection switch, avoiding the problem of inrush current to the device when the output relay closes due to the protection switch being open. It ensures that the relay only closes after the lithium battery module voltage actively approaches the charging system voltage through boost regulation, completely eliminating the risk of malfunction caused by unreasonable sampling point settings. This suppresses current surges during the closing process from the source, laying the most critical foundation for the safe and reliable operation of the entire lithium battery system. Furthermore, compared to the traditional method of setting sampling points on both sides of the output relay to determine the closing timing, this embodiment only requires a first sampling point and a second sampling point on one side of each output relay, greatly reducing the number of voltage sensors required. This achieves the effects of cost savings, reduced space occupation, and improved integration of the lithium battery system cabinet.

[0038] In one possible implementation, the specific implementation process of S101 includes: The voltage of the target lithium battery module is boosted according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then the target output relay is closed. The target lithium battery module can be any lithium battery module; the target output relay is the output relay corresponding to the target lithium battery module.

[0039] In this embodiment, when the target lithium battery module is not started or is in the slow start process, that is, when the voltage value of the second sampling point corresponding to the target lithium battery module is near zero, the system battery management unit sends the voltage value of the first sampling point to the battery pack management unit. The battery pack management unit controls the DC / DC converter in the lithium battery module to boost the voltage according to the voltage value of the first sampling point, and continuously monitors the voltage value of the second sampling point and receives the voltage value of the first sampling point sent by the system battery management unit. When the difference between the voltage value of the first sampling point and the voltage value of the second sampling point is less than a preset voltage difference, the target output relay is controlled to close, thereby realizing the parallel operation of the lithium battery module.

[0040] Specifically, to improve the accuracy of the output relay closing timing calculation, the battery pack management unit can control the target output relay to close when it detects that the voltage difference between the first and second sampling points for M consecutive sampling cycles is less than a preset voltage difference. Here, M = 2~5.

[0041] In one embodiment, each battery pack management unit can perform boost processing on the corresponding lithium battery module in parallel based on the voltage value of the first sampling point, and control the output relay to close when the closing time is reached.

[0042] As another embodiment, the system battery management unit can also perform time-sequential boost control processing on all standby lithium battery modules, sending boost control commands for different time periods to each lithium battery module, thereby avoiding instantaneous load impact on the charging system when all lithium battery modules are connected to the system at the same time.

[0043] As can be seen from the above embodiments, this embodiment uses the voltage on the charging system side as a reference to dynamically control the voltage boost of the target lithium battery module, so that its charging voltage gradually tracks and approaches the reference until the voltage difference between the two sides enters a preset safe range, at which point the corresponding output relay is closed. This mechanism can effectively overcome the problems of long waiting time and lag caused by relying solely on voltage difference judgment without active adjustment. By actively controlling the DC / DC converter to boost the voltage, the system can not only quickly reduce the voltage difference, but also achieve a smooth and controllable voltage synchronization process.

[0044] In one possible implementation, the implementation process of S101 further includes: S201: Determine the operating condition of the charging system based on the voltage value of the first sampling point; the operating condition includes a slow-start operating condition and a stable operating condition; S202: If the charging system is in a slow start-up state, the target lithium battery module is controlled to boost voltage according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the first preset voltage difference, and the target output relay is closed. S203: If the charging system is in a stable operating condition, the target lithium battery module is controlled to boost voltage according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the second preset voltage difference, and the target output relay is closed. The first preset voltage difference is greater than the second preset voltage difference.

[0045] In this embodiment, during the charging state, the slow start condition is the condition in which the output voltage gradually rises from the initial value (e.g., 0V) to the rated voltage at the initial stage of the charging system startup. The stable condition is the condition in which the voltage fluctuation range is small after the output voltage of the charging system reaches the rated value, which is the normal operating condition of the charging system.

[0046] Specifically, in this embodiment, during the slow-start condition when the charging system voltage is rising, a larger first preset voltage difference is used. This allows the output relay to close prematurely within a reasonable deviation range, thereby accelerating the system's grid connection speed, adapting to the dynamic characteristics of the startup phase, and avoiding the phenomenon where the voltage difference frequently exceeds the limit due to the lithium battery module's voltage rise not keeping up with the charging voltage rise, triggering the output relay to repeatedly close and preventing normal startup. After the charging system enters a stable operating condition, a stricter second preset voltage difference is used to ensure higher-precision voltage matching before closing, eliminating residual impact. This differentiated threshold control effectively solves the contradiction between startup efficiency and operational stability that a single threshold cannot simultaneously address. It enables the system to respond quickly to the slow-start process and achieve near-impact-free smooth connection after stabilization, improving the adaptability of the lithium battery system to different power supply environments and operating phases, and optimizing the overall dynamic performance of the system while ensuring equipment safety.

[0047] In one possible implementation, the specific implementation process of S201 includes: If the voltage value at the first sampling point continues to increase within a first preset time period and the rate of change of the voltage value at the first sampling point is less than a preset rate of change threshold, then the charging system is determined to be in a slow start-up state; otherwise, the charging system is determined to be in a stable state.

[0048] In this embodiment, the first preset duration is a time threshold used to determine whether the voltage rise is a continuous process, avoiding misjudging instantaneous voltage fluctuations as a slow-start condition. The preset rate of change threshold is a voltage change rate threshold used to distinguish between slow-start conditions and voltage surge conditions. Taking the charging state as an example, since the slow-start condition is the initial stage of the charging system startup, its output voltage starts from a lower value and gradually rises to the rated value with a relatively gentle slope. Therefore, the voltage change rate of the slow-start condition is usually lower than this threshold.

[0049] Specifically, under stable operating conditions, the charging system has been started up and the output voltage fluctuates slightly around the rated value, and is in a stable power supply state. Under this operating condition, the output voltage of the charging system is stable, so a smaller second preset voltage threshold can be selected to achieve a smooth connection with almost no impact.

[0050] Under slow start-up conditions, since the output voltage of the charging system itself is changing, a larger tracking error is allowed when closing the circuit, so as to prioritize the rapid commissioning of the lithium battery module.

[0051] As can be seen from the above embodiments, this embodiment, by tracking voltage change trends in real time, can reliably distinguish between normal slow-start processes and voltage fluctuations, interference, or stable states, avoiding control mode errors caused by misjudgments. This method ensures that the system automatically switches to the corresponding control strategy at the appropriate time, enhancing the versatility of the lithium battery system when used with different charging devices.

[0052] In one possible implementation, after determining the operating condition of the charging system based on the voltage value of the first sampling point, the method provided in this embodiment may further include: The corresponding preset voltage difference is determined based on the operating conditions of the charging system and the current ambient temperature; The voltage of the target lithium battery module is boosted based on the voltage value of the first sampling point until the voltage difference between the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the preset voltage difference, at which point the target output relay is closed.

[0053] Specifically, temperature affects component performance. At high temperatures, the current-carrying capacity and surge resistance of components such as relay contacts, fuses, and power semiconductors may decrease; at low temperatures, the battery's internal resistance increases, and the surge current corresponding to the same voltage difference may decrease. Therefore, it is possible to set an ambient temperature that is negatively correlated with a preset voltage difference.

[0054] Specifically, this embodiment first determines a basic preset voltage difference based on the operating conditions of the lithium battery system, namely, a first preset voltage difference for the slow-start condition and a second preset voltage difference for the stable condition. Then, based on the ambient temperature, the first preset voltage difference / the second preset voltage difference is adjusted to obtain the final preset voltage difference. Taking the first preset voltage difference as an example, when the ambient temperature is higher than a first temperature threshold, the first preset voltage difference is decreased by a target value; when the ambient temperature is lower than the second temperature threshold, the first preset voltage difference is increased by a target value, wherein the first temperature threshold is greater than the second temperature threshold.

[0055] In one possible implementation, the method provided in this embodiment further includes: Collect the voltage value at the third sampling point U3; the third sampling point U3 is located at the first terminal side of any output relay; By comparing the voltage value of the first sampling point with the voltage value of the third sampling point, if the difference between the voltage value of the first sampling point and the voltage value of the third sampling point is greater than a third preset voltage difference, a first reminder message is generated; the first reminder message is used to prompt the user not to close the protection switch.

[0056] Specifically, when the charging system is in the non-start or slow-start phase, the protection switch is open. The lithium battery module can still boost the voltage based on the voltage difference between the first and second sampling points, and close the output relay when the voltage reaches the slow-start voltage of the charging system. However, if the lithium battery module continues to boost the voltage after closing the output relay, the voltage difference between the first and third sampling points may become too large. If the protection switch is manually closed at this time, the components at the charging system end will be damaged due to the excessive voltage difference. In this embodiment, when the protection switch is open, it actively detects whether there is a dangerous voltage difference on both sides of the protection switch. If the voltage difference between the first and third sampling points exceeds a third preset voltage difference value, a first reminder message is generated to warn the user not to close the protection switch, thereby preventing serious accidents such as short circuit impact and arc damage caused by huge voltage differences from the source of operation. This method not only improves operational safety but also has a certain fault pre-diagnosis capability, such as identifying abnormal line contact or sampling faults. Therefore, this embodiment can significantly enhance the human-machine interaction safety of the lithium battery system and further reduce the risk of misoperation and maintenance costs.

[0057] In one possible implementation, another implementation process of S102 may include: The voltage value of the third sampling point is collected; the third sampling point is located on the first terminal side of each output relay. Determine whether the difference between the voltage value of the first sampling point and the voltage value of the third sampling point corresponding to the target lithium battery module is less than a first preset threshold. If the difference between the voltage value of the first sampling point and the voltage value of the third sampling point corresponding to the target lithium battery module is less than the first preset threshold, then the third sampling point is selected as the target sampling point; if the difference between the voltage value of the first sampling point and the voltage value of the third sampling point is greater than or equal to the first preset threshold, then the first sampling point is selected as the target sampling point. The voltage of the target lithium battery module is controlled to increase based on the voltage value of the target sampling point until the voltage difference between the second sampling point corresponding to the target lithium battery module and the voltage value of the target sampling point is less than a preset voltage difference, at which point the target output relay is closed.

[0058] Specifically, in a lithium battery system with multiple lithium battery modules operating in parallel, there may be situations where some lithium battery modules are connected to the system while others are not. In this case, if the voltage value at the third sampling point is greater than a certain value, and the difference between the voltage value at the first sampling point and the voltage value at the third sampling point corresponding to the target lithium battery module is less than a first preset threshold, it indicates that the charging system is in a stable state and the protection switch is closed. If the voltage value at the first sampling point is still used to calculate the closing time of the output relay, then the voltage value at the second sampling point of some connected lithium battery modules may be higher than the voltage value at the first sampling point, but the difference between the two is still within the preset voltage difference. When controlling the unconnected lithium battery modules to boost the voltage according to the voltage value at the first sampling point, the voltage value at the third sampling point will be increased to exceed the second voltage value, and the battery pack management unit will close the output relay of that lithium battery module. The second voltage value is the voltage value at the first sampling point minus the preset voltage difference. At this time, there will be a voltage difference of nearly twice the preset voltage difference at the connection point of the output relay of the connected lithium battery module and the disconnected lithium battery module. This causes the lithium battery module with higher voltage to backflow current from the connection point of the output relay to the lithium battery module with lower voltage, instantly charging a large current into the output electrolytic capacitor of the lithium battery module with lower voltage, resulting in the fuse blowing.

[0059] When the protection switch is off, all lithium battery modules are not connected to the charging system. The voltage of all lithium battery modules that need to be connected to the charging system can be boosted based on the voltage value of the first sampling point, and then the corresponding output relay will be closed when the closing time is reached.

[0060] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0061] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0062] Figure 4A schematic diagram of the control device for a lithium battery system provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below: like Figure 3 As shown, the control device 100 of the lithium battery system includes: Sampling module 110 is used to collect the voltage values ​​of a first sampling point and a second sampling point in the lithium battery system; wherein, the first sampling point is located on the first end side of the protection switch; and the second sampling point is located on the second end side of each output relay. The relay closing timing determination module 120 is used to determine the closing timing of the output relay based on the voltage value of the first sampling point and the voltage value of the second sampling point.

[0063] In one possible implementation, the relay closing timing determination module 120 includes: The voltage of the target lithium battery module is boosted according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then the target output relay is closed. The target lithium battery module can be any lithium battery module; the target output relay is the output relay corresponding to the target lithium battery module.

[0064] In one possible implementation, the relay closing timing determination module specifically includes: The operating condition determination unit is used to determine the operating condition of the charging system based on the voltage value of the first sampling point; the operating condition includes a slow start operating condition and a stable operating condition; The slow-start control unit is used to control the target lithium battery module to boost voltage according to the voltage value of the first sampling point if the charging system is in slow-start mode, until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a first preset voltage difference, and then close the target output relay. A stability control unit is used to control the target lithium battery module to boost voltage based on the voltage value of the first sampling point if the charging system is in a stable operating condition, until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a second preset voltage difference, and then close the target output relay. The first preset voltage difference is greater than the second preset voltage difference.

[0065] In one possible implementation, the operating condition determination unit is used for: If the voltage value at the first sampling point continues to increase within a first preset time period and the rate of change of the voltage value at the first sampling point is less than a preset rate of change threshold, then the charging system is determined to be in a slow start-up state; otherwise, the charging system is determined to be in a stable state.

[0066] In one possible implementation, the control device of the lithium battery system further includes a notification module for: Collect the voltage value at the third sampling point; the third sampling point is located on the first terminal side of any output relay. By comparing the voltage value of the first sampling point with the voltage value of the third sampling point, if the difference between the voltage value of the first sampling point and the voltage value of the third sampling point is greater than a third preset voltage difference, a first reminder message is generated; the first reminder message is used to prompt the user not to close the protection switch.

[0067] Figure 4 This is a schematic diagram of the controller provided in an embodiment of the present invention. Figure 4 As shown, the controller 4 in this embodiment includes a processor 40, a memory 41, and a computer program 42 stored in the memory 41 and executable on the processor 40. When the processor 40 executes the computer program 42, it implements the steps in the control method embodiments of the various lithium battery systems described above, for example... Figure 2 Steps S101 to S102 are shown. Alternatively, when the processor 40 executes the computer program 42, it implements the functions of each module / unit in the above-described device embodiments.

[0068] For example, the computer program 42 may be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 42 in the controller 4.

[0069] The controller 4 can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The controller 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will understand that... Figure 4 This is merely an example of controller 4 and does not constitute a limitation on controller 4. It may include more or fewer components than shown, or combine certain components, or different components. For example, the controller may also include input / output devices, network access devices, buses, etc.

[0070] The processor 40 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0071] The memory 41 can be an internal storage unit of the controller 4, such as a hard disk or memory of the controller 4. The memory 41 can also be an external storage device of the controller 4, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the controller 4. Furthermore, the memory 41 can include both internal storage units and external storage devices of the controller 4. The memory 41 is used to store the computer program and other programs and data required by the controller. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0072] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0073] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0074] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0075] In the embodiments provided by this invention, it should be understood that the disclosed devices / controllers and methods can be implemented in other ways. For example, the device / controller embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units 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 devices or units may be electrical, mechanical, or other forms.

[0076] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0077] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0078] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the control method embodiments of the various lithium battery systems described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0079] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A control method for a lithium battery system, characterized in that, The lithium battery system includes a protection switch and at least one lithium battery module; the lithium battery module includes an output relay and a lithium battery unit; the first end of the protection switch is used to connect to the charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit. The method includes: The voltage values ​​of the first sampling point and the second sampling point in the lithium battery system are collected; wherein, the first sampling point is located on the first end side of the protection switch; and the second sampling point is located on the second end side of each output relay. The closing timing of the output relay is determined based on the voltage values ​​of the first sampling point and the second sampling point.

2. The control method for a lithium battery system according to claim 1, characterized in that, Determining the closing timing of the output relay based on the voltage values ​​of the first sampling point and the second sampling point includes: The voltage of the target lithium battery module is boosted according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then the target output relay is closed. The target lithium battery module can be any lithium battery module; the target output relay is the output relay corresponding to the target lithium battery module.

3. The control method for a lithium battery system according to claim 2, characterized in that, The step of controlling the target lithium battery module to boost voltage based on the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then closing the target output relay, includes: The operating condition of the charging system is determined based on the voltage value at the first sampling point; the operating condition includes a slow-start operating condition and a stable operating condition. If the charging system is in a slow start-up mode, the target lithium battery module is controlled to boost voltage according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the first preset voltage difference, and the target output relay is closed. If the charging system is in a stable operating condition, the target lithium battery module is controlled to boost voltage according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than the second preset voltage difference, and the target output relay is closed. The first preset voltage difference is greater than the second preset voltage difference.

4. The control method for a lithium battery system according to claim 3, characterized in that, The step of determining the operating condition of the charging system based on the rate of change of the voltage value at the first sampling point includes: If the voltage value at the first sampling point continues to increase within a first preset time period and the rate of change of the voltage value at the first sampling point is less than a preset rate of change threshold, then the charging system is determined to be in a slow start-up state; otherwise, the charging system is determined to be in a stable state.

5. The control method for a lithium battery system according to claim 1, characterized in that, The method further includes: Collect the voltage value at the third sampling point; the third sampling point is located on the first terminal side of any output relay. By comparing the voltage value of the first sampling point with the voltage value of the third sampling point, if the difference between the voltage value of the first sampling point and the voltage value of the third sampling point is greater than a third preset voltage difference, a first reminder message is generated; the first reminder message is used to prompt the user not to close the protection switch.

6. A control device for a lithium battery system, characterized in that, The lithium battery system includes a protection switch and at least one lithium battery module; the lithium battery module includes an output relay and a lithium battery unit; the first end of the protection switch is used to connect to the charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit. The device includes: A sampling module is used to collect the voltage values ​​of a first sampling point and a second sampling point in the lithium battery system; wherein, the first sampling point is located on the first end side of the protection switch; and the second sampling point is located on the second end side of each output relay. The relay closing timing determination module is used to determine the closing timing of the output relay based on the voltage value of the first sampling point and the voltage value of the second sampling point.

7. The control device for a lithium battery system according to claim 6, characterized in that, The relay closing timing determination module includes: The voltage of the target lithium battery module is boosted according to the voltage value of the first sampling point until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a preset voltage difference, and then the target output relay is closed. The target lithium battery module can be any lithium battery module; the target output relay is the output relay corresponding to the target lithium battery module.

8. The control device for a lithium battery system according to claim 7, characterized in that, The relay closing timing determination module specifically includes: The operating condition determination unit is used to determine the operating condition of the charging system based on the voltage value of the first sampling point; the operating condition includes a slow start operating condition and a stable operating condition; The slow-start control unit is used to control the target lithium battery module to boost voltage according to the voltage value of the first sampling point if the charging system is in slow-start mode, until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a first preset voltage difference, and then close the target output relay. A stability control unit is used to control the target lithium battery module to boost voltage based on the voltage value of the first sampling point if the charging system is in a stable operating condition, until the difference between the voltage value of the second sampling point corresponding to the target lithium battery module and the voltage value of the first sampling point is less than a second preset voltage difference, and then close the target output relay. The first preset voltage difference is greater than the second preset voltage difference.

9. A controller comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the control method for the lithium battery system as described in any one of claims 1 to 5.

10. A lithium battery system, characterized in that, include: The controller, protection switch, at least one lithium battery module, and output relay corresponding to each lithium battery module as described in claim 9; the first end of the protection switch is used to connect to the charging system, the second end of the protection switch is directly connected to the first end of the output relay corresponding to each lithium battery module, and the second end of each output relay is connected to its corresponding lithium battery unit. The controller is used to execute the control method of the lithium battery system as described in any one of claims 1 to 5.

Images