Battery dynamic grouping discharging system based on MOS (Metal Oxide Semiconductor) switch

Abstract

The invention provides a battery dynamic grouping discharging system based on MOS switches. The battery dynamic grouping discharging system comprises a battery dynamic grouping discharging control unit and a battery dynamic grouping discharging topological structure responding to instructions of the battery dynamic grouping discharging control unit. The battery dynamic grouping discharge topological structure is used for switching on / off MOS switches connected to the battery monomers according to an instruction of the battery dynamic grouping discharge control unit so as to divide the battery monomers into a discharge group, a standby group and an offline group; and the battery dynamic grouping discharge control unit is used for sending a grouping instruction to the battery dynamic grouping discharge topological structure when the SOC value of the battery array reaches a lower limit value. By applying the technology, the battery array is divided into a discharging group, a standby group and an off-line group for operation, so that the battery array in a low-electric-quantity state is safely and stably operated, and meanwhile, the endurance mileage is prolonged; in addition, the dynamic grouping technology is adopted to exchange the battery monomers with the SOC value lower than the SOC value in the standby group in the discharging group for operation, the service cycle life of the battery array is prolonged, and the endurance mileage is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of battery management, and in particular to a battery dynamic grouping discharge system based on MOS switches. Background Art

[0002] The battery management system (BMS) of electric bicycles usually connects the MOS tubes connected to the battery cells in parallel to increase power, but this method has a flaw. When the battery is in a low-power state (remaining power SOC ≤ 20%), the rider's sudden acceleration will cause the battery cell to discharge with a large current instantly. The large current discharge will cause a rapid single-cell voltage drop. Because the discharge power of each battery cell at the end of the discharge is not the same, it will cause the voltage of a single battery cell to drop to the protection voltage threshold of the protection board, causing the protection board to directly activate the protection mechanism, disconnect the output MOS tube, and directly leave the rider stranded on the road. In addition, when the battery is in a low-power state, it is necessary to make full use of the remaining power so that the rider can find a charging station to charge or a battery swap cabinet to swap power, that is, to extend the battery life as much as possible when the battery is low. Therefore, it is a problem that needs to be solved at present to eliminate the insecurity caused by stranding when the battery of an electric bicycle is in a low-power state and to extend the cruising range as much as possible to facilitate smooth recharging. Summary of the invention

[0003] Based on the above situation, the main purpose of the present invention is to provide a battery dynamic grouping discharge system based on MOS switch control, so that the batteries can be dynamically grouped and operated when the battery is in a low-power state, with a part of batteries with similar power levels discharging at a low current and another part of batteries providing standby support. Battery cells that are about to reach an abnormal state can be taken offline to improve battery consistency, ensure safe operation, and extend the battery life.

[0004] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0005] The present invention provides a battery dynamic grouping discharge system based on MOS switches, comprising: a battery dynamic grouping discharge control unit, and a battery dynamic grouping discharge topology structure that responds to instructions of the battery dynamic grouping discharge control unit; the battery dynamic grouping discharge topology structure comprises: a battery array and a MOS switch array connected to each battery cell of the battery array; the MOS switch array switches on and off the MOS switches connected to the battery cells according to instructions of the battery dynamic grouping discharge control unit to divide the battery cells into a discharge group, a standby group and an offline group; the discharge group uses a small current to stably supply power to the load to ensure operation safety and improve the cruising range; the standby group provides standby support for the discharge group; the offline group disconnects the MOS switches connected to the battery cells according to instructions of the battery dynamic grouping discharge control unit to take the battery cells offline to protect the batteries and enable the batteries of the discharge group to operate stably; the battery cells of the discharge group and the standby group are switched on and off according to instructions of the battery dynamic grouping discharge control unit, and a small amount of batteries are replaced as needed to ensure the battery consistency of the discharge group and reduce the frequent switching of the batteries to protect the batteries; the battery dynamic grouping discharge control unit is used to continuously monitor the SOC value of the battery array during the discharge stage of the battery array, and when the SOC value of the battery array reaches a lower limit, send a grouping instruction to the battery dynamic grouping discharge topology structure.

[0006] Furthermore, the battery array includes: battery cells B1 to B1 connected in series n MOS switch array includes: each battery cell is connected to five MOS switches, which are the positive electrode MOS discharge switch D 1,1 ~D n,1 and MOS standby switch S 1,1 ~S n,1 , battery cell negative electrode MOS offline switch Q1~Q n , and connected to the MOS offline switches Q1~Q n The output end of the battery cell negative electrode MOS discharge switch D 1,2 ~D n,2 and MOS standby switch S 1,2 ~S n,2 .

[0007] Further, continuously monitoring the battery array SOC value includes monitoring: the total SOC value of the battery array and the SOC value of the battery cell; the lower limit value of the battery array SOC value includes: the total SOC lower limit value a1 of the battery array, the SOC lower limit value s1 of the battery cell and the offline value s2, where s1>s2; the instruction to send a group to the battery dynamic group discharge topology structure includes:

[0008] First clustering grouping instruction: When the total SOC value of the battery array drops to a1 or the SOC value of no less than one battery cell drops to s1, the battery dynamic grouping discharge control unit issues the first clustering grouping instruction to divide the battery cells with SOC values ​​above s2 into a discharge group and a standby group; through the first clustering grouping, batteries with the same power are divided into the same group for operation, thereby improving the consistency and stability of operation.

[0009] Dynamic replacement grouping instruction: In the continuous discharge stage after the battery array is first clustered and grouped, when there is at least one battery cell in the discharge group with an SOC value lower than that of at least one battery cell in the backup group, the at least one battery cell in the discharge group is exchanged with the battery cells in the backup group in descending order of SOC value; during the operation of the discharge group after the first clustering and grouping, the battery that loses power faster during discharge is exchanged with the battery with higher remaining power in the backup group, which can ensure the consistent and stable discharge of the batteries in the discharge group. At the same time, only a small number of batteries need to be switched to avoid the high energy consumption of frequent switching of a large number of batteries and the impact on reducing battery life.

[0010] If the SOC value of a battery cell drops to s2 during the continuous discharge phase of the battery array, the battery cell will be assigned to the offline group, which will no longer participate in operation and SOC value monitoring during this continuous discharge phase. By assigning batteries with low remaining power and close to over-discharge to the offline group for isolation, the battery can be protected from damage due to over-discharge before charging, while ensuring the stability of the discharge group battery.

[0011] Furthermore, the first clustering grouping method is the mean standard deviation clustering grouping method, specifically: sorting the SOC values ​​of battery cells with SOC values ​​above s2 and calculating the mean μ and standard deviation σ; dividing them into high, medium and low level intervals according to the mean μ and standard deviation σ, and dividing the battery cell SOC values ​​into corresponding levels; selecting battery cells divided into high-level intervals to the discharge group, and selecting battery cells divided into other levels to the standby group.

[0012] Preferably, the method for the first clustering grouping is the minimum-maximum scheduling method, specifically: battery sorting: sorting the SOC values ​​of battery cells above s2; selecting the initial clustering center: selecting the largest battery cell SOC value as the initial clustering center of the discharge group and selecting the smallest battery cell SOC value as the initial clustering center of the standby group; allocating battery cells: allocating each battery cell to the nearest initial clustering center according to the SOC value, the battery group allocated to the initial clustering center of the discharge group is the discharge group, and the battery group allocated to the initial clustering center of the standby group is the standby group.

[0013] Furthermore, the battery dynamic grouping discharge topology structure also includes an inductor L connected to the standby group, which is used for balancing between the battery cells in the standby group.

[0014] Furthermore, the battery dynamic group discharge control unit is also used to monitor the temperature of battery cells and MOS switches in real time. When the temperature reaches the set upper limit, the battery cells with too high temperature and the battery cells connected to the MOS switches with too high temperature are disconnected and assigned to the offline group to ensure stable and safe operation of the battery group.

[0015] Furthermore, if the battery cell is in the discharge group before disconnection, the battery cell with the highest SOC value in the standby group is added to the discharge group while disconnecting the battery cell to the offline group to keep the current of the discharge group stable.

[0016] The beneficial effects of the present invention include:

[0017] On the first aspect, when the battery array is low on power, the present invention adopts clustering grouping technology and utilizes the advantages of fast and stable switching of MOS switches to divide the battery array into a discharge group, a standby group and an offline group according to the SOC value, thereby solving the problem of excessive difference in SOC values ​​between battery cells, improving the consistency of the battery state of charge, and optimizing the discharge depth of the battery cells by reducing the number of discharged battery cells and maintaining a small current and stable discharge through the discharge group, thereby making the battery array in a low power state operate safely and stably while extending the cruising range.

[0018] Secondly, after the initial clustering and grouping, as the discharge continues, the present invention uses dynamic grouping technology to interchange battery cells in the discharge group whose SOC value is lower than that in the standby group, thereby switching groups of a small number of batteries and reducing the number of switching actions of traditional grouped battery cells, thereby improving the consistency of the charge state of the batteries in the discharge group and reducing the battery loss caused by frequent switching of battery cells, thereby improving the cycle life of the battery array and extending the cruising range.

[0019] Thirdly, the present invention takes offline batteries whose SOC values ​​drop to a state close to over-discharge and batteries whose temperatures are higher than an upper limit value, thereby protecting batteries in abnormal value states from damage due to high temperature or over-discharge, and protecting batteries in operation from being affected by abnormal value batteries in their stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The topological structure of the dynamic group discharge of batteries provided by the embodiment of the present invention is shown in FIG. Figure 1 .

[0021] Figure 2 The topological structure of the dynamic group discharge of batteries provided by the embodiment of the present invention is shown in FIG. Figure 2 .

[0022] Figure 3 The embodiment of the present invention provides a battery cell B1 and B n-1Offline, B2 and B n-2 Discharge, B3 and B n Schematic diagram of the discharge group conduction circuit and the standby group balancing circuit formed as a standby example. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0024] In the battery management system (BMS) of an electric bicycle, acceleration at low power may have the following effects on the battery and BMS: (1) Increased battery stress: At low power, the chemical activity of the battery may have decreased. At this time, acceleration will require the battery to provide a larger current, which may increase the stress on the battery and accelerate battery aging. (2) Thermal management challenges: The battery discharge current increases during acceleration, which may cause the battery temperature to rise. If the thermal management measures of the BMS are insufficient, it may cause the battery to overheat, affecting battery performance and life. (3) Safety risks: At low power, the battery voltage may have approached or reached the minimum voltage threshold set by the BMS. At this time, if acceleration continues, the battery voltage may be too low, triggering the BMS's safety protection mechanism, such as limiting output or directly disconnecting the circuit to prevent the battery from over-discharging. (4) BMS protection mechanism: The BMS may adjust its protection strategy according to the battery's power and voltage status, such as limiting power output, to ensure that the battery is not damaged by excessive discharge. (5) Performance degradation: At low power, in order to protect the battery, the BMS may limit the battery's discharge current, which will cause the acceleration performance of the electric vehicle to deteriorate. (5) Reduced mileage: As the battery discharge current increases during acceleration, the remaining battery power may be quickly depleted, resulting in reduced mileage. To meet these challenges, the BMS needs to have accurate battery status monitoring and effective protection mechanisms, such as over-temperature protection, over-current protection, and voltage protection, to ensure the safety and performance of the battery under various operating conditions. At the same time, the control strategy design of electric bicycles should also take into account the performance and safety of low-battery conditions, and guide users to use them reasonably through reasonable battery management and driving prompts.

[0025] In order to solve the problem that electric bicycles are prone to breaking down and causing insecurity when running in a low-battery state, and cannot reach the charging station or battery swap cabinet smoothly due to the low cruising range when running in a low-battery state, a battery dynamic grouping discharge system based on MOS switch control is proposed. The clustering and dynamic grouping technology is combined with the battery dynamic grouping topology structure. When the battery array is running at low power, it is divided into a discharge group, a standby group and an offline group. The discharged battery maintains good consistency and continuously and stably discharges at a small current, thereby improving the cruising range, making the battery array run safely and stably, and improving the cycle life of the battery array.

[0026] Please refer to Figure 1 , Figure 2In order to realize dynamic grouping of battery arrays, the present application provides a battery dynamic grouping discharge system based on MOS switches, including: a battery dynamic grouping discharge control unit, and a battery dynamic grouping discharge topology structure that responds to instructions of the battery dynamic grouping discharge control unit; the battery dynamic grouping discharge topology structure includes: a battery array and a MOS switch array connected to each battery cell of the battery array; the MOS switch array switches on and off the MOS switches connected to the battery cells according to the instructions of the battery dynamic grouping discharge control unit to divide the battery cells into a discharge group, a standby group and an offline group; the discharge group supplies power to the load; the standby group provides standby support for the discharge group; the offline group disconnects the MOS switches connected to the battery cells according to the instructions of the battery dynamic grouping discharge control unit to take the battery cells offline; the battery cells of the discharge group and the standby group switch on and off the MOS switches connected to the battery cells according to the instructions of the battery dynamic grouping discharge control unit and interchange them; the battery dynamic grouping discharge control unit is used to continuously monitor the SOC value of the battery array during the discharge stage of the battery array, and when the SOC value of the battery array reaches a lower limit, send a grouping instruction to the battery dynamic grouping discharge topology structure.

[0027] Specifically, due to poor consistency and low mileage, low-power batteries are prone to safety risks and are not conducive to timely recharging. The idea of ​​battery grouping can solve this problem. Battery grouping discharge has many advantages, including: (1) Improving battery pack performance. Balancing battery status: Through group discharge, batteries can be reasonably grouped according to their state of charge (SOC), voltage, internal resistance and other parameters, so that batteries in the same group have better consistency during discharge. This can avoid problems such as overcharging and over-discharging caused by battery inconsistency, give full play to the performance of each battery, and improve the overall discharge efficiency and capacity utilization of the battery pack. Optimizing charge and discharge management: Group discharge facilitates the implementation of targeted charge and discharge management strategies for batteries in different groups. For example, for battery groups with lower SOC, the charging current can be appropriately increased or the charging time can be extended; for battery groups with higher SOC, discharge management can be performed in advance, so as to better maintain the balance of the battery pack and extend the service life of the battery pack. (2) Enhancing system stability. Reduce the risk of failure: When there are batteries with abnormal values ​​close to failure in the battery pack, group discharge can isolate the batteries close to failure in a specific group to prevent them from having adverse effects on other normal batteries, such as causing thermal runaway to spread and causing short circuits, thereby effectively reducing the risk of failure of the entire battery system and improving the safety and reliability of the system; Improve anti-interference ability: Group discharge makes the battery pack more orderly when working and reduces mutual interference between batteries. Especially under high load or complex working conditions, this orderly discharge method can better cope with various emergencies, maintain the stable operation of the system, and improve the adaptability and stability of the battery pack under extreme conditions. (3) Improve energy utilization efficiency. Reduce energy loss: The use of group discharge technology can more accurately control the battery charging and discharging process, avoid excessive charging and discharging caused by battery inconsistency, thereby reducing energy loss caused by incomplete chemical reactions or internal short circuits, improve the energy conversion efficiency of the battery pack, and enable more electrical energy to be effectively output to the load end; Extend battery life: The balanced discharge state helps to slow down the aging of the battery and extend the battery life. This means that during the entire battery system life cycle, the battery can maintain high performance for a longer period of time, reducing energy waste caused by premature battery failure, and further improving energy utilization efficiency in the long run. (4) Easy to maintain and manage. Simplify maintenance work: Group discharge makes battery management more refined. Maintenance personnel can more intuitively understand the status of each group of batteries and quickly locate faulty batteries or battery packs with abnormal performance, so as to carry out targeted maintenance and replacement, improve maintenance efficiency and reduce maintenance costs. Improve management accuracy: The battery management system (BMS) can more accurately monitor and control the grouped batteries and realize independent management of each battery group. This refined management method can better adapt to the changes of batteries in different use stages and working conditions, and provide stronger guarantees for the healthy operation of batteries.(5) Adapt to different application scenarios. Meet diverse needs: In different application scenarios, the performance and capacity requirements for batteries are different. Battery group discharge can flexibly adjust the configuration and working mode of each group of batteries according to specific needs to meet the needs of diverse applications such as electric vehicles, energy storage systems, and portable electronic devices; Improve system flexibility: Group discharge technology enables the battery system to quickly adjust and optimize when facing different workloads and usage scenarios. For example, during the driving of an electric bicycle, the discharge strategy of the battery pack can be dynamically adjusted according to road conditions and driving needs to achieve optimal energy distribution and improve the vehicle's cruising range and power performance. At present, battery grouping technology is mainly used for power distribution in wind power storage systems, and the batteries are often fixed into two or more groups, which are charged and discharged in turn. In this solution, for example, when an electric bicycle is running in a low-battery state, it is necessary to save energy more accurately and increase the range. Therefore, fixed grouping cannot meet the solution to the current problem. This solution combines cluster grouping and dynamic grouping, and uses the advantages of MOS switch switching speed and high flexibility to build a dynamic grouping battery topology structure, which can flexibly and accurately switch batteries in groups, and can meet the goals of saving energy, improving safety and extending the range.

[0028] Specifically, the trigger condition for battery group switching in this solution is the battery SOC lower limit value. The SOC value can accurately reflect the remaining power of the battery, avoid premature exhaustion or over-discharge, and thus extend the battery's range; accurate SOC values ​​help prevent overcharging and over-discharging of the battery, both of which may cause permanent damage to the internal structure of the battery and even cause safety issues. By accurately controlling the SOC, the battery management system (BMS) can ensure that the battery always operates within a safe voltage range; when the SOC value approaches the battery's limit value, the BMS can issue a warning signal in time according to the SOC value and take corresponding protective measures, such as cutting off the charging or discharging circuit to prevent battery damage and ensure the safe operation of the system. This solution uses the SOC lower limit value as a trigger grouping mechanism to make the timing of grouping accurate, which can not only protect the safe and stable operation of the battery, but also save energy and improve battery life.

[0029] In order to quickly and stably respond to the operation strategy of the battery dynamic group discharge unit, the battery dynamic group discharge topology includes a battery array and a MOS switch array. The battery array includes: battery cells B1~B1 connected in series n MOS switch array includes: each battery cell is connected to five MOS switches, which are the positive electrode MOS discharge switch D 1,1 ~D n,1 and MOS standby switch S 1,1 ~S n,1 , battery cell negative electrode MOS offline switch Q1~Q n, and connected to the MOS offline switches Q1~Q n The output end of the battery cell negative electrode MOS discharge switch D 1,2 ~D n,2 and MOS standby switch S 1,2 ~S n,2 .

[0030] Specifically, the battery dynamic grouping discharge topology is suitable for the battery array discharge state. Figure 1 As shown, the topology includes n battery cells and 5n MOS switches, and the value of n is general. In a continuous group discharge process, the n battery cells are dynamically grouped by turning on and off the MOS switches according to instructions.

[0031] In order to accurately monitor the battery SOC value and issue grouping instructions accurately and timely, the battery dynamic group discharge control unit integrates the SOC value monitoring scheme and group discharge control strategy into the control chip with software programming equations for adaptive control. The continuous monitoring of the battery array SOC value includes monitoring: the total SOC value of the battery array and the SOC value of the battery cell; the lower limit values ​​include: the total SOC lower limit value a1 of the battery array, the SOC lower limit value s1 of the battery cell and the offline value s2, where s1>s2; the instructions for issuing grouping to the battery dynamic group discharge topology structure include: (1) the first clustering grouping instruction: when the total SOC value of the battery array drops to a1 or the SOC value of at least one battery cell drops to s1, the battery dynamic group discharge The control unit issues a first clustering grouping instruction to divide the battery cells with SOC values ​​above s2 into a discharge group and a standby group; (2) a dynamic grouping change instruction: during the continuous discharge phase after the first clustering grouping of the battery array, when there is at least one battery cell in the discharge group with an SOC value lower than that of at least one battery cell in the standby group, the at least one battery cell in the discharge group is exchanged with the battery cells in the standby group in descending order of SOC values; (3) during the continuous discharge phase of the battery array, if there is a battery cell with an SOC value lower than s2, the battery cell is divided into an offline group, and the offline group no longer participates in operation and SOC value monitoring during this continuous discharge phase.

[0032] Specifically, when the SOC value of the battery array is at a higher stage, all batteries can be involved in the discharge operation to maintain the high-efficiency operation of the load. When the SOC value drops to a low-power state, the number of batteries in the discharge operation is reduced to maintain a small current discharge for safety and endurance considerations. Usually, the SOC value of the electric bicycle warning that it needs to be charged is 20%. In this solution, for the sake of safe and stable operation and improved endurance, the battery array SOC lower limit a1 is set to 30%, and it can also be customized according to the usage scenario. The SOC lower limit of the single cell is divided into a group lower limit s130% and an offline lower limit s210%, which can also be customized using the scenario. After the above lower limit is customized, it is embedded in the control strategy and the system performs adaptive control.

[0033] In order to ensure that the batteries in the discharge group and the standby group maintain good consistency and continuous and stable discharge, the first clustering grouping method is the mean standard deviation clustering grouping method, specifically: sort the SOC values ​​of the battery cells above s2 and calculate the mean μ and standard deviation σ; divide them into high, medium and low level intervals according to the mean μ and standard deviation σ, and divide the battery cell SOC values ​​into corresponding levels; select the battery cells divided into the high level interval to the discharge group, and select the battery cells divided into the remaining levels to the standby group.

[0034] Specifically, the mean-standard deviation clustering method is a clustering algorithm that determines the cluster center and divides the data points based on the mean and standard deviation of the data. This method is particularly suitable for processing data sets with different degrees of discreteness. The steps of the mean-standard deviation clustering method are as follows: (1) Data preprocessing: Centering transformation: First, calculate the sample mean of each variable, and then subtract the mean of the variable from the original data to obtain the centered data. In this way, the sum of each column of data is 0, that is, the mean of each variable is 0; Standardization transformation: Based on the centering transformation, the standard deviation of the variable is used for standardization. In this way, the mean of each column of data in the data matrix is ​​0 and the variance is 1. The data no longer has a dimension, which facilitates comparison between different variables. (2) Calculate the mean and standard deviation: Calculate the mean and standard deviation of each variable. The mean represents the center position of the data, and the standard deviation represents the degree of discreteness of the data. (3) Determine the initial cluster center: Use the standard deviation to define the initial center point candidate set. Select data points with larger standard deviations as the initial cluster centers, so as to avoid selecting sample points with lower density, especially isolated points, as the initial center points; Clustering process: Assign data points: Assign each data point to the cluster where the nearest cluster center is located; Update cluster centers: Recalculate the mean and standard deviation of each cluster based on the assigned data points, and update the cluster centers; Iteration: Repeat the above steps until the cluster center no longer changes or reaches the predetermined number of iterations. (4) Evaluate clustering results: Calculate cluster standard deviation: Use the combined standard deviation formula to calculate the standard deviation of each cluster, the formula is: Where n1 and n2 are the sample sizes of group 1 and group 2, respectively, and σ1 and σ2 are the standard deviations of group 1 and group 2, respectively. Advantages of the mean-standard deviation clustering method: (1) Robustness: This method is less sensitive to isolated points and has good robustness. By selecting data points with larger standard deviations as the initial cluster centers, isolated points can be avoided. (2) Adaptability: The number of clusters can be adaptively determined. Based on the principle that cluster centers usually have higher density and are farther apart, a method for determining the number of clusters during the clustering process is defined. (3) Flexibility: It is applicable to clusters of different shapes and sizes. The standard deviation can reflect the degree of discreteness of the data, making the selection of cluster centers more flexible and adaptable to clusters of different shapes. (4) Computational efficiency: The computational complexity of this method is relatively low and it is suitable for processing large-scale data sets. By gradually increasing the initial center point, the amount of calculation can be reduced and the clustering efficiency can be improved.

[0035] Optionally, in order to maintain a high computational efficiency, the first clustering grouping method is the minimum-maximum scheduling method, specifically: battery sorting: sorting the SOC values ​​of battery cells above s2; selecting the initial clustering center: selecting the largest battery cell SOC value as the initial clustering center of the discharge group and selecting the smallest battery cell SOC value as the initial clustering center of the standby group; allocating battery cells: allocating each battery cell to the nearest initial clustering center according to the SOC value, the battery group allocated to the initial clustering center of the discharge group is the discharge group, and the battery group allocated to the initial clustering center of the standby group is the standby group.

[0036] Specifically, the min-max scheduling clustering method is a distance-based clustering algorithm whose main idea is to optimize the clustering process by selecting the initial cluster center. The advantages of this method are: (1) No need to pre-specify the number of clusters: The min-max scheduling clustering method does not need to pre-specify the number of clusters, which makes it more flexible in processing data and suitable for situations where the number of clusters is unknown. (2) Strong robustness: This method is relatively robust in the selection of initial cluster centers and can effectively avoid the problem of inaccurate clustering results caused by improper selection of initial centers. By selecting the point farthest from the current cluster center as the new cluster center, the data space can be better covered. (3) Good robustness to noise and outliers: When selecting the initial cluster center, this method can effectively avoid selecting noise points or outliers as the initial center through the maximum and minimum distance principle, thereby improving the stability of the clustering results. (4) Relatively low computational complexity: Compared with some complex hierarchical clustering methods, the min-max scheduling clustering method has a relatively low computational complexity and is suitable for processing medium-sized data sets.

[0037] In order to make the backup group batteries maintain consistency during the battery operation stage and provide backup support for the discharge group, the battery dynamic group discharge topology also includes an inductor L connected to the backup group for balancing between the backup group battery cells.

[0038] Specifically, please refer to Figure 3 , for battery cells B1 and B n-1 Offline, B2 and B n-2 Discharge, B3 and B n An embodiment of a discharge group conduction circuit and a standby group balancing circuit formed as a standby.

[0039] In order to protect batteries with abnormal temperatures and the stability of battery operation, the battery dynamic grouping discharge control unit is also used to monitor the temperature of battery cells and MOS switches in real time. When the temperature reaches the set upper limit, the battery cells with too high temperature and the battery cells connected to the MOS switches with too high temperature are disconnected and assigned to the offline group.

[0040] Specifically, batteries with too high temperatures will have the following adverse effects: (1) Performance degradation. Reduced capacity: High temperature will accelerate the chemical reactions inside the battery, causing the battery capacity to gradually decrease. For example, for every 1°C increase in temperature, the capacity may increase by 0.8% of the original value, but this increase is temporary, and long-term high temperature will cause irreversible capacity decay. In an environment with a normal temperature of 25°C, if the temperature rises by 6-10°C, the battery life may be reduced by half; Increased internal resistance: High temperature will increase the internal resistance of the battery and reduce the battery's charging and discharging efficiency. This will cause the battery to generate more heat during the charging and discharging process, further aggravating the aging of the battery. Voltage drop: High temperature will cause the battery's voltage output to decrease, weakening the battery's ability to effectively supply power. (2) Safety issues. Thermal runaway risk: Under extremely high temperatures, the battery is prone to thermal runaway, that is, the heat generated inside the battery cannot be dissipated in time, causing the temperature to rise rapidly, and may even cause fire or explosion. (3) Shortened battery life. Accelerated chemical reactions: High temperature will accelerate the speed of chemical reactions inside the battery, causing the battery to undergo faster chemical changes during the charging and discharging process. This will increase the internal resistance of the battery, reduce the battery capacity and efficiency; Material degradation: High temperature will accelerate the degradation of internal battery materials, such as corrosion and decomposition of electrode materials. These chemical changes will shorten the service life of the battery; Increased side reactions: High temperature leads to an increase in the side reaction of the anode reducing the electrolyte, and the inorganic products of the reaction are deposited on the anode surface, hindering the deintercalation of lithium ions and accelerating the aging of the battery. At high temperatures, the battery side reactions increase, such as the SEI film on the surface of the negative electrode will decompose, rupture or dissolve, resulting in continuous consumption of lithium ions during the cycle at high temperature, and the capacity decreases rapidly. In order to protect batteries with excessive temperatures and batteries that operate normally, it is an effective method to isolate batteries with excessive temperatures offline. Excessive temperature of the MOS switch connected to the battery cell will also lead to performance degradation, thermal runaway risk and failure risk. The MOS switch and battery can be protected by cutting off.

[0041] In order to maintain the stable low-current operation of the discharge group, if the battery cell or MOS switch with high temperature before disconnection is in the discharge group, disconnect the battery cell to the offline group and add the battery cell with the highest SOC value in the standby group to the discharge group. If the battery cell or MOS switch with high temperature before disconnection is in the standby group, directly cut off the MOS switch to divide the battery cell into the offline group.

[0042] The following is a specific implementation example of battery management using a battery dynamic grouping discharge system:When a bicycle is running at low power, firstly, it is easy for the rider to be stranded on the road, resulting in a poor experience for the rider; secondly, the battery life cannot last to the charging point or the battery swap cabinet. Using the solution of this application, multiple MOS tubes are managed in groups, and software is used for programmatic management. For example: when the SOC is fully charged, all MOS tubes are turned on. When the SOC value is 10-20%, the MOS is turned on in groups to reduce the external output current and avoid the protection board protection caused by the rapid voltage drop of a single battery cell. At the same time, the temperature of each group of MOS tubes is monitored, and the output is turned off when the upper limit is reached. At the same time, another group of MOS is started to maintain a small current and stable discharge to ensure that the rider can find the battery swap cabinet to replace the fully charged battery. It is generally recommended that every 2 pairs of MOS are in a group, and 4-5 groups are required for the takeaway and logistics industries. 2 pairs of MOS are required for civilian use. Controlling the output current and speed at the end to prevent the rider from being stranded halfway improves the experience and reduces the discovery of the rider being seized by the traffic police.

[0043] It should be noted that the number of groups in the present solution can also be used to subdivide the discharge group into multiple groups for discharge in turn to meet the different application scenarios described in the above embodiments. At the same time, according to the road conditions of conventional use, the lower limit of the trigger group can also be adjusted. For example, on city roads and on uneven roads, the required current is different, so the number of discharge groups in operation is different. In addition, in order to more fully improve the endurance energy, an energy recovery unit can also be set to recover energy during braking or coasting and store it in a spare group, thereby better improving the battery life. The battery monomer described in this solution can refer to a single battery cell or a battery unit formed by multiple battery cells connected in series / parallel.

[0044] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

[0045] It should be noted that the above-described embodiments are only some embodiments of the present invention, rather than all embodiments. The singular forms "a", "the" and "it" used in the embodiments and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

Claims

1. A battery dynamic grouping discharge system based on MOS switches, characterized in that: include: A battery dynamic grouping discharge control unit, and a battery dynamic grouping discharge topology structure responsive to an instruction of the battery dynamic grouping discharge control unit; The battery dynamic group discharge topology structure includes: a battery array and a MOS switch array connected to each battery cell in the battery array; The MOS switch array divides the battery cells into a discharge group, a standby group and an offline group by switching on and off the MOS switches connected to the battery cells according to the instructions of the battery dynamic group discharge control unit; the discharge group supplies power to the load; the standby group provides standby support for the discharge group; the offline group disconnects the MOS switches connected to the battery cells according to the instructions of the battery dynamic group discharge control unit to take the battery cells offline; the battery cells of the discharge group and the standby group switch on and off the MOS switches connected to the battery cells interchangeably according to the instructions of the battery dynamic group discharge control unit; The battery dynamic grouping discharge control unit is used to continuously monitor the battery array SOC value during the battery array discharge phase, and when the battery array SOC value reaches a lower limit, issue a grouping instruction to the battery dynamic grouping discharge topology structure.

2. The battery dynamic grouping discharge system according to claim 1, characterized in that: The battery array includes: battery cells B1 to B1 connected in series n ; The MOS switch array includes: each battery cell is connected to five MOS switches, which are the positive electrode MOS discharge switch D 1,1 ~D n,1 and MOS standby switch S 1,1 ~S n,1 , battery cell negative electrode MOS offline switch Q1~Q n , and connected to the MOS offline switches Q1~Q n The output end of the battery cell negative electrode MOS discharge switch D 1,2 ~D n,2 and MOS standby switch S 1,2 ~S n,2 .

3. The battery dynamic grouping discharge system according to claim 1, characterized in that: The continuous monitoring of the battery array SOC value includes monitoring: the total SOC value of the battery array and the SOC value of the battery cell; The lower limit values ​​include: the total SOC lower limit value a1 of the battery array, the SOC lower limit value s1 of the battery cell and the offline value s2, where s1>s2; The instruction of issuing grouping to the battery dynamic grouping discharge topology structure comprises: First clustering grouping instruction: When the total SOC value of the battery array drops to a1 or the SOC value of at least one battery cell drops to s1, the battery dynamic grouping discharge control unit issues the first clustering grouping instruction to divide the battery cells with SOC values ​​above s2 into a discharge group and a standby group; Dynamic grouping change instruction: In the continuous discharge stage after the battery array is first clustered, if there is at least one battery cell in the discharge group with an SOC value lower than that of at least one battery cell in the backup group, the battery cells in the discharge group will be exchanged with those in the backup group in descending order of SOC value. If the SOC value of a battery cell drops to s2 during the continuous discharge phase of the battery array, the battery cell is divided into an offline group, and the offline group no longer participates in operation and SOC value monitoring during this continuous discharge phase.

4. The battery dynamic grouping discharge system according to claim 3, characterized in that: The first clustering grouping method is a mean standard deviation clustering grouping method, specifically: Sort the SOC values ​​of the battery cells with SOC values ​​above s2 and calculate the mean μ and standard deviation σ; According to the mean μ and standard deviation σ, the battery cell SOC value is divided into high, medium and low level intervals, and the battery cell SOC value is divided into corresponding levels; The battery cells classified into the high-level range are selected to the discharge group, and the battery cells classified into the remaining levels are selected to the standby group.

5. The battery dynamic grouping discharge system according to claim 3, characterized in that: The method for the first clustering grouping is a minimum-maximum scheduling method, specifically: Battery sorting: Sort the battery cells with SOC values ​​above s2 by SOC value; Select the initial cluster center: select the largest battery cell SOC value as the initial cluster center of the discharge group and select the smallest battery cell SOC value as the initial cluster center of the standby group; Allocate battery cells: Allocate each battery cell to the nearest initial cluster center according to the SOC value. The battery group assigned to the initial cluster center of the discharge group is the discharge group, and the battery group assigned to the initial cluster center of the standby group is the standby group.

6. The battery dynamic grouping discharge system according to claim 1 or 2, characterized in that: The battery dynamic grouping discharge topology structure further includes an inductor L connected to the standby group, which is used for balancing between the battery cells in the standby group.

7. The battery dynamic grouping discharge system according to claim 1, characterized in that: The battery dynamic grouping discharge control unit is also used to monitor the temperature of battery cells and MOS switches in real time. When the temperature reaches a set upper limit, the battery cells with too high temperature and the battery cells connected to the MOS switches with too high temperature are disconnected and allocated to the offline group.

8. The battery dynamic grouping discharge system according to claim 7, characterized in that: If the battery cell is in the discharge group before disconnection, the battery cell with the highest SOC value in the standby group is added to the discharge group while the battery cell is disconnected to the offline group.

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