Power supply system

Abstract

The application provides a power supply system, which comprises a plurality of battery clusters, an access unit and a first BMS management unit; the battery cluster comprises a plurality of battery packs and a second BMS management unit; the battery pack comprises a battery module, a first DC / DC converter and a third BMS management unit; the third BMS management unit acquires the external characteristic parameters of each battery cell unit; the second BMS management unit is signal connected with each third BMS management unit and judges whether each battery pack is abnormal, and further receives a cluster output target to control the electric output parameters of each battery pack; the first BMS management unit is signal connected with each second BMS management unit to acquire the abnormal information of each battery pack in each battery cluster, and starts and stops the corresponding cluster access switch and sends the cluster output target to the second BMS management unit of each battery cluster. The above-mentioned power supply system is suitable for expansion and has good personnel safety, and is convenient for wiring and suitable for coping with battery failure.

Description

Technical Field

[0001] This invention relates to the technical field of batteries and battery-powered applications, and more particularly to power supply systems. Background Technology

[0002] Currently, UPS systems are widely used. In the event of a mains power failure, the UPS typically switches to battery power to ensure uninterrupted power supply to the load. However, as load levels increase, the UPS output power also needs to increase, requiring the battery module's output power to match the increased power in battery power mode.

[0003] In existing UPS systems, the battery module typically consists of multiple battery packs. When capacity expansion is needed, it is usually achieved by connecting more battery packs in series or by using battery packs with more individual cells. However, because the voltage gain of the DC / DC converter inside the UPS is not high, the need to connect more batteries in series during capacity expansion results in a higher output voltage for the battery module. This poses a certain safety hazard to personnel operating and maintaining the battery module. Summary of the Invention

[0004] The purpose of this invention is to overcome at least one defect or problem existing in the prior art and to provide a power supply system that is suitable for capacity expansion and has better personnel safety.

[0005] To achieve the above objectives, the technical solution of the present invention is: a power supply system, comprising: a plurality of battery clusters, an access unit, and a first BMS management unit; the battery clusters have cluster connection terminals and include a plurality of interconnected battery packs, and a second BMS management unit; the battery packs include battery modules, a first DC / DC converter, and a third BMS management unit; the battery modules include a plurality of interconnected cell units; the low-voltage side of the first DC / DC converter is connected to the battery modules, and its high-voltage side forms the pack connection terminal of the battery pack, and is used to realize voltage transformation between the battery modules and the pack connection terminal; the third BMS management unit is used to acquire the external characteristic parameters of each cell unit; wherein, each battery pack establishes a voltage distribution network through the pack connection terminal. The connection relationship is defined and the cluster connection end is identified; the second BMS management unit is signal-connected to the third BMS management unit of each battery pack in its battery cluster, so as to determine whether each battery pack is abnormal based on the external characteristic parameters of the cell units of each battery pack; the second BMS management unit also receives a cluster output target to control the electrical output parameters of each battery pack; the access unit is used to access each battery cluster, and includes a plurality of cluster access switches corresponding to the cluster connection end of each battery cluster; the first BMS management unit is signal-connected to the second BMS management unit of each battery cluster to obtain the abnormal information of each battery pack in each battery cluster, and opens or closes the corresponding cluster access switch according to the abnormal information and sends the corresponding cluster output target to the second BMS management unit of each battery cluster.

[0006] Furthermore, the pack connection ends of each of the battery packs are connected in parallel to a common end, which constitutes the cluster connection end of the battery cluster.

[0007] Furthermore, the cluster output target is a given value for cluster output power; the second BMS management unit cuts off all battery packs in the corresponding battery cluster when the cluster output target is zero; the second BMS management unit cuts off abnormal battery packs in the corresponding battery cluster when the cluster output target is not zero, and performs PWM modulation on the first DC / DC converter in other battery packs according to the cluster output target, so as to adjust the output power of the corresponding battery cluster by adjusting the output voltage and output current of the corresponding battery pack.

[0008] Furthermore, the first BMS management unit determines the degree of abnormality of each battery cluster based on the number of abnormal battery packs within each cluster, and allocates and sends a corresponding cluster output target to each battery cluster in combination with the degree of abnormality and the current system output target; when all battery packs in a battery cluster are abnormal, the first BMS management unit closes the cluster access switch corresponding to that battery cluster and allocates and sends the cluster output target with a value of zero to the corresponding second BMS management unit; when there are non-abnormal battery packs in a battery cluster, the first BMS management unit keeps the cluster access switch corresponding to that battery cluster open and allocates and sends the cluster output target with a value of non-zero to the corresponding second BMS management unit.

[0009] Furthermore, the first BMS management unit allocates and sends cluster output targets with non-zero values ​​to each battery cluster that is connected to the access unit according to a weighted principle.

[0010] Furthermore, the battery pack also includes several equalization circuits, each of which is connected in series between two adjacent cell units and includes equalization resistors and equalization switches connected in series with each other; the external characteristic parameters include the voltage of the cell unit, and the third BMS management unit also turns on and off the corresponding equalization switches according to the voltage of each cell unit to perform voltage equalization on the corresponding cell unit.

[0011] Furthermore, the external characteristic parameters include voltage, current, and temperature; the second BMS management unit also calculates the SOC and / or SOH of each battery pack based on the external characteristic parameters of the cell units of each battery pack.

[0012] Furthermore, the maximum output voltage of each battery module is less than 65V; the number of cell units in each battery module is the same, and each cell unit consists of two single lithium batteries connected in parallel.

[0013] Furthermore, the access unit has a first end and a second end, the first end of which is connected to each battery cluster, and the second end of which is connected to the first end through a corresponding cluster access switch; the first DC / DC converter in each battery pack is a bidirectional DC / DC converter; the power supply system also includes a converter device, which has a battery end and includes a DC bus, a second DC / DC converter, and a second DC / DC control unit; the battery end is connected to the second end of the access unit to connect to each battery cluster; the second DC / DC converter is a bidirectional DC / DC converter and its two sides are respectively connected to the DC bus and the battery end to realize voltage conversion between the two; the second DC / DC control unit is used to control the second DC / DC converter to keep it on; the battery cluster also includes a first voltage acquisition unit for acquiring the voltage at its cluster connection end; each battery pack includes a first DC / DC control unit for controlling the working direction of the corresponding first DC / DC converter; each first DC / DC control unit signal When the voltage at the cluster connection terminal is lower than a first threshold, the first DC / DC converter is controlled to operate in the discharge direction so that the corresponding battery module discharges to the converter. When the voltage at the cluster connection terminal is higher than a second threshold, each of the first DC / DC control units controls the corresponding first DC / DC converter to operate in the charging direction so that the corresponding battery module is charged by the converter. The first threshold is less than or equal to the second threshold. The converter also includes a second voltage collector for collecting the voltage of the DC bus. The second DC / DC control unit is connected to the second voltage collector to obtain the DC bus voltage. When the DC bus voltage is lower than a third threshold, the second DC / DC control unit controls the second DC / DC converter to operate in the discharge direction. When the DC bus voltage is higher than a fourth threshold, the second DC / DC control unit controls the second DC / DC converter to operate in the charging direction. The third threshold is less than or equal to the fourth threshold.

[0014] Furthermore, the converter also includes an AC / DC converter and a DC / AC converter; the DC sides of both the AC / DC converter and the DC / AC converter are connected to the DC bus, the AC side of the AC / DC converter is connected to an AC power source, and the AC side of the DC / AC converter outputs AC power; the high-voltage side of the second DC / DC converter is connected to the DC bus, and its low-voltage side is connected to the battery terminal.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] (1) The power supply system includes several battery clusters, each battery cluster includes several battery packs, and each battery pack includes a first DC / DC converter. This first DC / DC converter is coupled to the battery modules to convert the output voltage of the battery modules and output it, thus eliminating the need to significantly increase the output voltage of the battery modules to expand the power supply system using the battery packs and battery clusters. In other words, even when the battery modules themselves output a low voltage, the aforementioned battery pack can still maintain a certain output voltage to meet the needs of the power supply system during operation; and when maintenance is required, the battery pack can be maintained relatively safely because the output voltage of the battery modules is not high. Therefore, the above structure effectively improves the safety of personnel during the maintenance and operation of the battery pack, thereby making the corresponding power supply system suitable for expansion without worrying about personnel safety issues.

[0017] Furthermore, the power supply system of the present invention adopts a three-level BMS management architecture on the basis of the above. The three-level BMS management units are located at the battery pack level, the battery cluster level and the power supply system level, respectively, and perform corresponding BMS management for the cell unit, battery pack and battery cluster. This makes the power supply system even more convenient for expansion due to other advantages.

[0018] Specifically, since the battery pack has a third BMS management unit for acquiring the external characteristic parameters of each cell, the second BMS management unit only needs to communicate with each third BMS management unit to obtain the external characteristic parameters of each cell to determine whether each battery pack is abnormal. Therefore, the second BMS management unit does not need to be connected to each cell through a large number of wiring harnesses. The wiring relationship of the signal lines in the battery pack is simpler and less prone to errors. Moreover, since the signal lines are shorter, signal interference and delay can be effectively improved, which facilitates the management of the battery pack and makes it easier to expand capacity.

[0019] Furthermore, the power supply system of this invention adopts a three-level BMS management architecture with interconnected systems. Each level of BMS management unit manages its respective sub-level battery layer based on information reported by the BMS management unit at the sub-level battery layer. For example, the third BMS management unit is located at the battery pack level and can manage each cell unit; the second BMS management unit is located at the battery cluster level and manages each battery pack; and the first BMS management unit is located at the power supply system level and manages each battery cluster. This prevents a situation where a battery layer automatically cuts off its output after detecting a certain degree of fault, thereby causing significant output pressure on other parts of the same battery layer. For example, taking the battery cluster level as an example, if there is an abnormal or faulty battery pack in a battery cluster, and the BMS management unit in that battery cluster controls that battery cluster to directly stop power output, this will cause significant output pressure on other battery clusters of the same level. At this time, it is possible that only some battery packs in the battery cluster are abnormal, while some battery packs are still suitable for power output, thus significantly wasting the portion of battery packs that are still suitable for power output. In actual configuration, it is difficult to achieve communication between each battery cluster and any other battery cluster. This would prevent each battery cluster from knowing the operating status of other battery clusters and adjusting its own output accordingly using the battery packs that can still provide power. Consequently, it would be impossible to address and resolve the aforementioned waste phenomenon.

[0020] In this invention, the second BMS management unit uploads abnormal battery pack information within the corresponding battery cluster to the first BMS management unit. This allows the first BMS management unit to accurately obtain abnormal information about each battery pack within each battery cluster and perform global control of each battery cluster based on this information. This includes determining whether each battery cluster is connected and supplying power, and the cluster output target that each connected and supplying power needs to achieve. Next, the second BMS management unit, upon receiving the cluster output target, can control the electrical output parameters of the battery packs within the battery cluster that are still suitable for supplying power. This ensures that all battery packs cooperate and that the battery cluster achieves the aforementioned cluster output target, thus fully utilizing all available battery packs in the power supply system and effectively achieving the overall system's operational objectives, thereby improving the stability of the power supply system. In other words, the three-level BMS management architecture of the power supply system employs an upward reporting mechanism and a downward management mechanism at the communication and control levels, respectively, and effectively combines the two. This solves the problem of underutilization of battery packs that may exist after the power supply system is expanded, thus making the power supply system suitable for expansion.

[0021] It can also be seen that, due to the clear hierarchy of the battery section within the power supply system, with corresponding BMS management units at each level from battery packs and battery clusters to the entire power supply system, it is convenient to perform modular configuration of each part and to manage the battery section of the entire power supply system effectively.

[0022] (2) The battery packs are connected in parallel to define the battery clusters, so that each battery pack forms a battery cluster through parallel connection. Even if the number of cell units contained in the battery module of the battery pack is small and the output voltage of the battery pack is low, the discharge performance of the battery cluster can be effectively improved, which is especially beneficial to the uninterruptible power supply application of the power supply system.

[0023] (3) The cluster output target is the cluster output power setpoint. Each second BMS management unit cuts off the abnormal battery pack according to the cluster output target and performs PWM modulation on each first DC / DC converter according to the cluster output target to adjust the output voltage and current of each battery pack, thereby adjusting the output power of the corresponding battery cluster. In other words, the second BMS control unit can use the switch of the first DC / DC converter to control whether the battery pack supplies power, without the need to set up a dedicated charging and discharging control switch, reducing the number of switches required for the battery pack, improving the switch utilization rate, reducing the cost of the battery pack, and further adapting to the expansion of the power supply system.

[0024] (4) The first BMS management unit determines the degree of abnormality of each battery cluster based on the number of abnormal battery packs in each battery cluster. Then, it can allocate a reasonable cluster output target corresponding to the degree of abnormality to each battery cluster, so as to make full use of each battery pack.

[0025] (5) The first BMS management unit allocates the corresponding cluster output target to each access battery cluster according to the weighting principle. In other words, the cluster output target of the battery cluster with high abnormal battery pack inventory is low, and the cluster output target of the battery cluster with high non-abnormal battery pack inventory is high. This can prevent the rapid aging of some battery packs under the uniformity principle and is suitable for maintaining each battery pack with basically the same lifespan.

[0026] (6) The battery pack is equipped with an equalization circuit. The third BMS management unit turns on and off the corresponding equalization switch according to the voltage of each cell to perform voltage equalization on the corresponding cell, which can effectively extend the life of each cell.

[0027] (7) The second BMS management unit calculates the SOC and SOH of each battery pack based on the external characteristic parameters of the cell units of each battery pack, providing data support for the charge and discharge control of the battery pack and the evaluation of battery life.

[0028] (8) The maximum output voltage of the battery pack is below 65V, ensuring the safety of personnel during maintenance. Each cell unit consists of two parallel lithium-ion cells, which increases the current level that the cell unit can handle, resulting in a long lifespan and stable discharge, thereby improving the discharge performance of the battery pack. The number of cell units in each battery module is the same, which can prevent parallel circulating current to a certain extent.

[0029] (9) The power supply system includes a converter. The battery terminals of the converter are connected to each battery cluster through an access unit, thereby introducing DC power from each battery cluster and converting it into a wider range of applications. In addition, since each battery cluster is connected to the battery terminal of the converter instead of the DC bus, there is no need to modify the existing converter, which improves its versatility.

[0030] Since the battery pack is equipped with a bidirectional DC / DC converter, this invention further includes a first DC / DC control unit. This first DC / DC control unit can control the operating direction of each first DC / DC converter and match the operating requirements of the power converter simply by comparing the voltage at the cluster connection terminal with a preset threshold. Specifically, the reason for this is that since each battery cluster is electrically coupled to the power converter to discharge to or be charged by it, and each battery cluster is connected to the power converter through a cluster connection terminal, the operating requirements of the power converter can be mapped to the voltage at the cluster connection terminal. Therefore, the control unit can obtain the operating requirements of the power converter and perform corresponding control actions to match those operating requirements simply by looking at the voltage at the cluster connection terminal.

[0031] In other words, the control of the first DC / DC converter in each battery pack can be independent of the control of the converter. It does not require a direct communication connection with the converter via an industrial control bus and a complex control algorithm. This allows each battery pack to match the operating requirements of the power supply system. When the number of battery packs is large, this is especially suitable for reducing the complexity of communication and control at the actual application of battery clusters, reducing the difficulty of field wiring, and making the power supply system easy to expand.

[0032] Furthermore, the power supply system incorporates a key configuration for the converter device. Specifically, the second DC / DC control unit keeps the second DC / DC converter on while the converter is operating. This ensures that the DC bus voltage, appropriate to reflect the converter's operational requirements, is transmitted to the cluster connection terminals of each battery cluster via the second DC / DC converter. This guarantees that each battery cluster can always obtain an effective cluster connection terminal voltage that maps to the converter's operational needs. The first DC / DC control unit effectively controls the first DC / DC converter to match the converter's operational requirements, thereby ensuring the stable operation of the power supply system.

[0033] In addition, the second DC / DC control unit controls the operating direction of the second DC / DC converter by acquiring the DC bus voltage, which ensures high stability.

[0034] (10) The converter has an AC / DC converter and a DC / AC converter, which makes the power supply system a UPS power supply system suitable for expansion. It can stably supply power to the load in battery power mode. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments are briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a topology diagram of the power supply system according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the battery cluster structure according to an embodiment of the present invention;

[0038] Figure 3 This is a topological diagram of a battery cluster according to an embodiment of the present invention;

[0039] Figure 4 This is a topology diagram of a battery pack according to an embodiment of the present invention;

[0040] Figure 5 This is another topological diagram of the battery pack according to an embodiment of the present invention;

[0041] Figure 6 This is another topology diagram of the power supply system according to an embodiment of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] Battery cluster 100; cluster connection terminal 101; battery pack 110; pack connection terminal 110A; battery module 111; cell unit 111A; first DC / DC converter 112; first DC / DC controller 112A; equalization circuit 113; equalization resistor 113A; equalization switch 113B; third BMS management unit 114; second BMS management unit 120; first voltage acquisition unit 130; access unit 200; first BMS management unit 300; converter 400; battery terminal 401; AC / DC converter 410; DC / AC converter 420; second DC / DC converter 430; second DC / DC controller 440; second voltage acquisition unit 450. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are preferred embodiments of the present invention and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and accompanying drawings of this invention is for distinguishing different objects and not for describing a specific order.

[0046] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0047] In the claims, description and drawings of this invention, unless otherwise expressly defined, the term "connection" may include both direct and indirect connections; the term "coupling" refers to two electrical modules having specific circuit functions after being connected.

[0048] Reference Figure 1 This invention provides a power supply system comprising a plurality of battery clusters 100, an access unit 200, and a first BMS management unit 300.

[0049] like Figure 2-3 As shown, the battery cluster 100 has a cluster connection end 101 and includes a plurality of battery packs 110 connected to each other and a second BMS management unit 120.

[0050] like Figure 3-5 As shown, the battery pack 110 includes a battery module 111, a first DC / DC converter 112, several equalization circuits 113, and a third BMS management unit 114.

[0051] Reference Figure 3 and Figure 5 The battery module 111 includes a plurality of battery cell units 111A connected in series. In this embodiment, the maximum output voltage of the battery module 111 is all below 65V, ensuring the safety of personnel maintenance. The number of battery cell units 111A in each battery module 111 is the same, which can prevent parallel circulating current to a certain extent. Each battery cell unit 111A consists of two single lithium batteries connected in parallel, such as... Figure 5 As shown, this increases the current level that the cell unit 111A can handle, has a longer lifespan and more stable discharge, thereby improving the discharge performance of the battery pack 110.

[0052] Reference Figure 3 and Figure 4The low-voltage side of the first DC / DC converter 112 is connected to the battery module 111, and its high-voltage side forms the pack connection terminal 110A of the battery pack 110, which is used to realize voltage transformation between the battery module 111 and the pack connection terminal 110A. In this embodiment, the first DC / DC converter 112 is a bidirectional DC / DC converter, which can use existing converters and is not limited to a specific DC / DC circuit topology. It goes without saying that when the battery module 111 is discharging, its electrical energy is boosted and output by the first DC / DC converter 112; when the battery module 111 is charging, the DC power input to the pack connection terminal 110A is stepped down by the first DC / DC converter 112 to charge the battery module 111. In addition, in the battery cluster 100, each battery pack 110 establishes an electrical connection relationship through the pack connection terminal 110A and defines the cluster connection terminal 101. The specific form is determined by the specific series and parallel structure of each battery pack 110. In this embodiment, the pack connection terminals 110A of each battery pack 110 are connected in parallel to a common terminal, which constitutes the cluster connection terminal 101 of the battery cluster 100. This makes the battery packs 110 in this embodiment form a typical parallel output structure. Even if the number of cell units 111A contained in the battery module 111 of the battery pack 110 is small and the output voltage of the battery pack 110 is low, the discharge performance of the battery cluster 100 can be effectively improved, which is especially beneficial for the uninterruptible power supply application of the power supply system.

[0053] Reference Figure 5 The plurality of equalization circuits 113 are connected in series between two adjacent battery cells 111A, and each includes an equalization resistor 113A and an equalization switch 113B connected in series with each other.

[0054] Reference Figure 3 and Figure 5 The third BMS management unit 114 acquires the external characteristic parameters of each battery cell 111A and performs voltage equalization management on each battery cell 111A. The external characteristic parameters include the voltage, current, and temperature of the battery pack 110. Therefore, the third BMS management unit 114 also includes corresponding sensors, which will not be detailed here. Specifically, the third BMS management unit 114 activates or deactivates the equalization switch 113B of the corresponding equalization circuit 113 according to the voltage of each battery cell 111A to perform voltage equalization on the corresponding battery cell 111A, which can effectively extend the life of each battery cell 111A.

[0055] Reference Figure 2-3The second BMS management unit 120 is signal-connected to the third BMS management unit 114 of each battery pack 110 in the battery cluster 100 to determine whether each battery pack 110 is abnormal based on the external characteristic parameters of the cell units 111A of each battery pack 110. It is understood that the second BMS management unit 120 determines that the corresponding battery pack 110 is abnormal or faulty when it is under overvoltage, overcurrent, or overtemperature. Furthermore, the second BMS management unit 120 also calculates the SOC and / or SOH of each battery pack 110 based on the external characteristic parameters of the cell units 111A of each battery pack 110, providing data support for charge and discharge control of the battery pack 110 and evaluation of battery life.

[0056] Furthermore, the second BMS management unit 120 also receives a cluster output target to control the electrical output parameters of each battery pack 110. The cluster output target is issued by the first BMS management unit 300, which will be described below. In this embodiment, the cluster output target is a cluster output power setpoint. Thus, the second BMS management unit 120 can adjust the output power of each battery pack 110 by adjusting the output current and output voltage of each battery pack 110. The specific control loop can be a voltage-current dual closed-loop control, etc., which is not specifically limited in this embodiment. Specifically, when the cluster output target is zero, the second BMS management unit 120 cuts off all battery packs 110 in the corresponding battery cluster 100, thereby removing the battery cluster 100 from the power supply output from this side. When the cluster output target is not zero, the second BMS management unit 120 cuts off the abnormal battery pack 110 in the corresponding battery cluster 100, and performs PWM modulation on the first DC / DC converter 112 in other battery packs 110 according to the cluster output target, so as to adjust the output power of the corresponding battery cluster 100 by adjusting the output voltage and output current of the corresponding battery pack 110. In other words, the second BMS control unit can use the switch of the first DC / DC converter 112 to control whether the battery pack 110 supplies power, without the need to set up a dedicated charging and discharging control switch, reducing the number of switches required for the battery pack 110, improving the switch utilization rate, reducing the cost of the battery pack 110, and further adapting to the expansion of the power supply system.

[0057] Reference Figure 1The access unit 200 is used to access each battery cluster 100. It includes several cluster access switches (not shown in the figure) corresponding to the cluster connection terminals 101 of each battery cluster 100. Each cluster access switch can be a corresponding relay or contactor. It is understood that the access unit 200 can be a physical power distribution device, such as a busbar-type power distribution cabinet. In this way, the DC power output from each battery cluster 100 can be distributed through the access unit 200 and connected to other power conversion devices, thereby converting the DC power of each battery cluster 100 into other forms of electrical energy before output, expanding the application scenarios of each battery cluster 100. As described above, the access unit 200 can be connected to a power conversion device 400 (in... Figure 6 (As shown in the diagram), each battery cluster 100 is electrically coupled to the converter 400 to discharge at least to it. Specifically, the converter 400 can be any part of the UPS power system other than the conventional batteries, including rectification, inversion, and boost converters, the specific structure of which will be detailed below. Therefore, when each battery cluster 100 is connected to the converter 400 through the access unit 200, the power supply system essentially constitutes a UPS power supply system to provide uninterrupted power to the load. It should be noted that the access unit 200 should not be limited to being a physical power distribution device. In fact, the access switches included in the access unit 200 can be located inside each battery cluster 100 or inside the corresponding converter.

[0058] Reference Figure 1 The first BMS management unit 300 is signal-connected to the second BMS management unit 120 of each battery cluster 100 to obtain abnormal information of each battery pack 110 within each battery cluster 100. Based on this abnormal information, it activates / deactivates the corresponding cluster access switch and sends the corresponding cluster output target to the second BMS management unit 120 of each battery cluster 100. Specifically, in this embodiment, the first BMS management unit 300 determines the degree of abnormality of each battery cluster 100 based on the number of abnormal battery packs 110 within each battery cluster 100. For example, if the battery cluster 100 includes 10 battery packs 110, then when all 10 battery packs 110 are abnormal, the degree of abnormality is 10; when all 3 battery packs 110 are abnormal, the degree of abnormality is 3; and when all battery packs 110 are normal, the degree of abnormality is 0. In this way, the first BMS management unit 300 can combine the anomaly level with the current system output target to allocate and send reasonable cluster output targets corresponding to the anomaly level of each battery cluster 100, thereby achieving full utilization of each battery pack 110. The current system output target is sent to the first BMS management unit 300 by the host computer based on the actual system operation.

[0059] In this embodiment, when all battery packs 110 within the battery cluster 100 are abnormal, the first BMS management unit 300 closes the cluster access switch corresponding to that battery cluster 100 and allocates and sends the cluster output target with a value of zero to the corresponding second BMS management unit 120. When there are non-abnormal battery packs 110 within the battery cluster 100, the first BMS management unit 300 keeps the cluster access switch corresponding to that battery cluster 100 open and allocates and sends the cluster output target with a value of non-zero to the corresponding second BMS management unit 120.

[0060] Preferably, the first BMS management unit 300 allocates and sends non-zero cluster output targets to each battery cluster 100 that is connected to the access unit 200 according to a weighted principle. In other words, the cluster output target of battery clusters 100 with high inventory levels of abnormal battery packs 110 is low, and the cluster output target of battery clusters 100 with high inventory levels of non-abnormal battery packs 110 is high. This can prevent rapid aging of some battery packs 110 under the uniformity principle and is suitable for maintaining each battery pack 110 with a basically the same lifespan.

[0061] As can be seen from the above description of the power supply system, the power supply system includes several battery clusters 100, each battery cluster 100 includes several battery packs 110, and each battery pack 110 includes a first DC / DC converter 112. This first DC / DC converter 112 is coupled to the battery module 111 to convert the output voltage of the battery module 111 before outputting it. Therefore, it is not necessary to significantly increase the output voltage of the battery module 111 to expand the capacity of the power supply system using the battery packs 110 and battery clusters 100. In other words, even when the battery module 111 itself outputs a relatively low voltage, the battery pack 110 can still maintain a certain output voltage to meet the needs of the power supply system during operation. Furthermore, when maintenance is required, the low output voltage of the battery module 111 allows for relatively safe maintenance of the battery pack 110. Therefore, the above structure effectively improves the safety of personnel during the maintenance and operation of the battery pack 110, making the corresponding power supply system suitable for capacity expansion without concerns about personnel safety.

[0062] Furthermore, the power supply system of this embodiment of the invention further adopts a three-level BMS management architecture on the basis of the above. The three-level BMS management units (114, 120, 300) are respectively located at the battery pack level, battery cluster level and power supply system level, and perform corresponding BMS management for the cell unit 111A, battery pack 110 and battery cluster 100. This makes the power supply system even more convenient for expansion due to other advantages.

[0063] Specifically, since the battery pack 110 has a third BMS management unit 114 for obtaining the external characteristic parameters of each cell unit 111A, the second BMS management unit 120 only needs to communicate with each third BMS management unit 114 to obtain the external characteristic parameters of each cell unit 111A to determine whether each battery pack 110 is abnormal. Therefore, the second BMS management unit 120 does not need to be connected to each cell unit 111A through a large number of wiring harnesses. The wiring relationship of the signal lines in the battery cluster 100 is relatively simple and less prone to errors. Moreover, since the signal lines are short, the signal interference and delay can be effectively improved, which facilitates the management of the battery cluster 100 and makes it easier to expand the capacity.

[0064] Furthermore, the power supply system of this embodiment adopts a three-level BMS management architecture that communicates with each other. Each level of BMS management unit manages its sub-level battery layer based on the information reported by the BMS management unit of the sub-level battery layer. For example, the third BMS management unit 114 is located at the battery pack level and can be used to manage each cell unit 111A, the second BMS management unit 120 is located at the battery cluster level and is used to manage each battery pack 110, and the first BMS management unit 300 is located at the power supply system level and is used to manage each battery cluster 100. This prevents a situation where a certain battery layer automatically cuts off its output after detecting a certain degree of fault, thereby causing a large output pressure on other parts of the same battery layer.

[0065] In this embodiment of the invention, the second BMS management unit 120 uploads abnormal information of the battery packs 110 within the corresponding battery cluster 100 to the first BMS management unit 300. This allows the first BMS management unit 300 to accurately obtain abnormal information of each battery pack 110 within each battery cluster 100 and to perform global control of each battery cluster 100 based on this abnormal information. This includes determining whether each battery cluster 100 is connected and supplying power, and the cluster output target that each connected and supplying power needs to achieve. Subsequently, the second BMS management unit 120, upon receiving the cluster output target, can control the power output parameters of the battery packs 110 within the battery cluster 100 that are still suitable for supplying power. This allows each battery pack 110 to cooperate and enable the battery cluster 100 to achieve the aforementioned cluster output target. As a result, all available battery packs 110 in the power supply system are fully utilized, effectively achieving the overall system's operational objective and improving the stability of the power supply system. In other words, the three-level BMS management architecture of the power supply system adopts an upward reporting mechanism and a downward management mechanism at the communication and control levels, respectively, and effectively combines the two. This solves the defect that the battery pack 110 may not be fully utilized after the power supply system is expanded, thus making the power supply system suitable for expansion.

[0066] It can also be seen that, due to the clear hierarchy of the battery section in the power supply system, from the battery pack 110 and battery cluster 100 to the entire power supply system, there are corresponding BMS management units at each level, which facilitates modular configuration of each part and good management of the battery section of the entire power supply system.

[0067] Continue to refer to Figure 6 This embodiment, based on the above, also has the following preferred configuration. However, it should be noted that... Figure 6 Only one battery cluster 100 is shown, and the various levels of BMS management units and access units 200 are not included. Figure 6 As shown in the image.

[0068] The access unit 200 has a first end and a second end. Its first end is connected to each battery cluster 100, and its second end is connected to the first end through a corresponding cluster access switch.

[0069] The power supply system also includes the aforementioned converter 400, which has a battery terminal 401 and includes a DC bus, a second DC / DC converter 430, and a second DC / DC control unit. The battery terminal 401 is connected to the second terminal of the access unit 200 to connect to each of the battery clusters 100, thereby allowing the DC power from each battery cluster 100 to be introduced and transformed for wider applications. The second DC / DC converter 430 is a bidirectional DC / DC converter with its two sides connected to the DC bus and the battery terminal 401 respectively to achieve voltage transformation between the two. Therefore, since each battery cluster 100 is connected to the battery terminal 401 of the converter 400 instead of the DC bus, no modification to the existing converter 400 is required, resulting in good versatility. In this embodiment, the second DC / DC control unit is used to control the second DC / DC converter 430 to remain on.

[0070] The battery cluster 100 further includes a first voltage acquisition unit 130 for acquiring the voltage at its cluster connection terminal 101. Each battery pack 110 includes a first DC / DC control unit for controlling the operating direction of a corresponding first DC / DC converter 112. Each first DC / DC control unit is signal-connected to the first voltage acquisition unit 130 and, when the voltage at the cluster connection terminal 101 is lower than a first threshold, controls the corresponding first DC / DC converter 112 to operate in the discharge direction (i.e., in boost mode) so that the corresponding battery module 111 discharges to the converter 400; when the voltage at the cluster connection terminal 101 is higher than a second threshold, each first DC / DC control unit controls the corresponding first DC / DC converter 112 to operate in the charging direction (i.e., in buck mode) so that the corresponding battery module 111 is charged by the converter 400. The first threshold is less than or equal to the second threshold.

[0071] In this embodiment, the first threshold and the second threshold have a certain difference to provide a buffer space. Furthermore, the first DC / DC control unit includes several first DC / DC controllers 112A corresponding to each first DC / DC converter 112. Each first DC / DC controller 112A is connected to the first voltage acquisition unit 130 to obtain the voltage of the cluster connection terminal 101 and uses it to control the operating direction of the corresponding first DC / DC converter 112. Specifically, each first DC / DC controller 112A controls the operating direction of the corresponding first DC / DC converter 112 by modulating the duty cycle of the PWM signal. This method is applicable to most DC / DC converters, is widely used, and the technology is relatively mature. Since using PWM modulation to control DC / DC converters is an existing technology, the specific process and principle will not be described in detail in this invention.

[0072] Since the battery pack 110 is equipped with a bidirectional DC / DC converter, this embodiment of the invention further includes a first DC / DC control unit. This first DC / DC control unit can control the operating direction of each first DC / DC converter 112 and match the operating requirements of the converter device 400 simply by comparing the voltage of the cluster connection terminal 101 with a preset threshold. Specifically, the reason for this is that since each battery cluster 100 is electrically coupled to the converter device 400 to discharge to or be charged by it, and each battery cluster 100 is connected to the converter device 400 through the cluster connection terminal 101, the operating requirements of the converter device 400 can be mapped to the voltage of the cluster connection terminal 101. Thus, the control unit can obtain the operating requirements of the converter device 400 and perform corresponding control actions to match the operating requirements simply by comparing the voltage of the cluster connection terminal 101. In this embodiment, the "operational requirements of the converter 400" specifically includes two situations: one is that the converter 400 is insufficient in supply, requiring the cooperation of each battery cluster 100 to jointly supply power; the other is that the converter 400 is excessive in supply, and there is no need for the cooperation of each battery cluster 100 to jointly supply power.

[0073] In other words, the control of the first DC / DC converter 112 in each battery pack 110 can be independent of the control of the converter 400. It does not require a direct communication connection with the converter 400 through the industrial control bus and to be given a complex control algorithm. This allows each battery pack 110 to match the operating requirements of the power supply system. When the number of battery packs 110 is large, this is especially suitable for reducing the complexity of the battery cluster 100 in actual application at the communication and control levels, reducing the difficulty of field wiring, and making the power supply system easy to expand.

[0074] Furthermore, the power supply system of this embodiment of the invention also includes a key configuration for the converter 400. Specifically, the second DC / DC control unit controls the second DC / DC converter 430 to remain on when the converter is operating. This ensures that the DC bus voltage suitable for reflecting the operating requirements of the converter 400 can be transmitted to the cluster connection terminal 101 of each battery cluster 100 through the second DC / DC converter 430. This guarantees that each battery cluster 100 can obtain an effective cluster connection terminal 101 voltage that maps to the operating requirements of the converter 400 at any time. The first DC / DC control unit effectively controls the first DC / DC converter 112 to match the operating requirements of the converter 400, thereby ensuring the stable operation of the power supply system.

[0075] Correspondingly, the converter 400 also includes a second voltage acquisition unit 450 for acquiring the voltage of the DC bus. The second DC / DC control unit is a second DC / DC controller 440, which is connected to the second voltage acquisition unit 450 to obtain the DC bus voltage. When the DC bus voltage is lower than a third threshold, the second DC / DC controller 440 controls the second DC / DC converter 430 to operate in the discharge direction; when the DC bus voltage is higher than a fourth threshold, the second DC / DC controller 440 controls the second DC / DC converter 430 to operate in the charging direction. The third threshold is less than or equal to the fourth threshold. In this embodiment, the third threshold and the fourth threshold have a certain difference. Therefore, this embodiment controls the operating direction of the second DC / DC converter 430 by acquiring the DC bus voltage, resulting in high stability.

[0076] It is worth noting that in the terminology system of this invention, both "charging direction" and "discharging direction" refer to the battery module 111. That is, for any DC / DC converter, "charging direction" refers to the direction in which electrical energy flows from the converter 400 to the battery cluster 100, and conversely, "discharging direction" refers to the direction in which electrical energy flows from the battery cluster 100 to the converter 400.

[0077] Specifically, as mentioned above, the converter 400 in this embodiment is the part of the UPS system excluding the traditional battery; that is, the converter 400 also includes an AC / DC converter 410 and a DC / AC converter 420. The DC sides of both the AC / DC converter 410 and the DC / AC converter 420 are connected to the DC bus. The AC side of the AC / DC converter 410 is connected to an AC power source, and the AC side of the DC / AC converter 420 outputs AC power. The high-voltage side of the second DC / DC converter 430 is connected to the DC bus, and its low-voltage side is connected to the battery terminal 401. In this embodiment, the AC power source is AC mains power. Since the rectification and inversion processes in the UPS system are existing technologies, they will not be described in detail here.

[0078] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this invention, but does not constitute a limitation on the scope of protection of this invention. Modifications, equivalent substitutions, or other improvements to the embodiments of this invention or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this invention or the foregoing embodiments, in conjunction with common knowledge, general technical knowledge, and / or existing technology, should all be included within the scope of protection of this invention.

Claims

1. A power supply system, characterized by, The power supply system comprises: a plurality of battery clusters, an access unit, a first BMS management unit and a power conversion device; each of the battery clusters has a cluster connection end and comprises a plurality of battery packs connected to each other, a second BMS management unit, and each of the battery packs comprises a battery module, a first DC / DC converter and a third BMS management unit, each of the battery modules comprises a plurality of battery cell units connected to each other in series, and the maximum output voltage of each of the battery modules is lower than 65V, the first DC / DC converter is a bidirectional DC / DC converter, the low-voltage side of the first DC / DC converter is connected to the battery module, the high-voltage side of the first DC / DC converter forms a pack connection end of the battery pack, and the first DC / DC converter is used to realize voltage conversion between the battery module and the pack connection end, and the third BMS management unit is used to obtain the external characteristic parameters of each battery cell unit, wherein the pack connection ends of the battery packs are connected to each other in parallel at a common end, and the common end constitutes the cluster connection end of the battery cluster, the second BMS management unit is signal connected to the third BMS management units of the battery packs of the battery cluster where the second BMS management unit is located, so as to determine whether each battery pack is abnormal according to the external characteristic parameters of the battery cell units of each battery pack, and the second BMS management unit also receives a cluster output target to control the electrical output parameters of each battery pack; the access unit is used to access each battery cluster, and comprises a plurality of cluster access switches corresponding to the cluster connection ends of the battery clusters; the first BMS management unit is signal connected to the second BMS management units of the battery clusters to obtain abnormal information of each battery pack in each battery cluster, and according to the abnormal information, the first BMS management unit opens or closes the corresponding cluster access switch and sends the corresponding cluster output target to the second BMS management units of the battery clusters; the power conversion device has a battery end and comprises a DC bus, a second DC / DC converter, an AC / DC converter and a DC / AC converter, the battery end is connected to the second end of the access unit to connect each of the battery clusters, the second DC / DC converter is a bidirectional DC / DC converter, the high-voltage side of the second DC / DC converter is connected to the DC bus, and the low-voltage side of the second DC / DC converter is connected to the battery end to realize voltage conversion between the two, the DC sides of the AC / DC converter and the DC / AC converter are connected to the DC bus, the AC side of the AC / DC converter is connected to an AC power supply, and the AC side of the DC / AC converter outputs AC power.

2. The power supply system of claim 1, wherein: The cluster output target is a cluster output power given value; when the cluster output target is zero, the second BMS management unit cuts off all the battery packs in the corresponding battery cluster; when the cluster output target is not zero, the second BMS management unit cuts off the abnormal battery packs in the corresponding battery cluster, and according to the cluster output target, the second BMS management unit performs PWM modulation on the first DC / DC converters in the other battery packs to adjust the output power of the corresponding battery cluster by adjusting the output voltage and the output current of the corresponding battery pack.

3. The power supply system of claim 2, wherein: the first BMS management unit determines the abnormality degree of each battery cluster according to the number of abnormal battery packs in each battery cluster, and assigns and sends the corresponding cluster output target to each battery cluster in combination with the abnormality degree and the current system output target. The first BMS management unit closes the cluster access switch corresponding to the battery cluster when all battery packs in the battery cluster are abnormal, and allocates and sends the cluster output target with a value of zero to the corresponding second BMS management unit; The first BMS management unit keeps the cluster access switch corresponding to the battery cluster open when there is a non-abnormal battery pack in the battery cluster, and allocates and sends the cluster output target with a value other than zero to the corresponding second BMS management unit.

4. The power supply system of claim 3, wherein: The first BMS management unit allocates and sends the cluster output target with a value other than zero to each battery cluster that keeps accessing the access unit according to a weighting principle.

5. The power supply system of claim 1, wherein: The battery pack further comprises a plurality of balancing circuits, each balancing circuit being connected in series between two adjacent cell units and comprising a balancing resistor and a balancing switch connected in series with each other; The external characteristic parameters include the voltage of the cell unit, and the third BMS management unit further opens and closes the corresponding balancing switch according to the voltage of the cell unit to balance the voltage of the corresponding cell unit.

6. The power supply system of claim 1, wherein: The external characteristic parameters include voltage, current and temperature; The second BMS management unit further calculates the SOC and / or SOH of each battery pack according to the external characteristic parameters of the cell units of each battery pack.

7. The power supply system of any one of claims 1-6, wherein: The number of cell units in each battery module is the same, and each cell unit is composed of two single lithium batteries connected in parallel with each other.

8. The power supply system of any one of claims 1-6, wherein: The access unit has a first end and a second end, the first end of which is connected to each battery cluster, and the second end of which is connected to the first end through the corresponding cluster access switch; The current conversion device further comprises a second DC / DC control unit; the second DC / DC control unit is used to control the second DC / DC converter to keep open; The battery cluster further comprises a first voltage collector for collecting the voltage of the cluster connection end; each battery pack comprises a first DC / DC control unit for controlling the working direction of the corresponding first DC / DC converter; each first DC / DC control unit is signal connected to the first voltage collector and controls the corresponding first DC / DC converter to work in the discharging direction when the voltage of the cluster connection end is lower than a first threshold value, so that the corresponding battery module discharges to the current conversion device; each first DC / DC control unit controls the corresponding first DC / DC converter to work in the charging direction when the voltage of the cluster connection end is higher than a second threshold value, so that the corresponding battery module is charged by the current conversion device; wherein the first threshold value is less than or equal to the second threshold value; The current conversion device further comprises a second voltage collector for collecting the voltage of the DC bus; the second DC / DC control unit is connected to the second voltage collector to obtain the DC bus voltage; the second DC / DC control unit controls the second DC / DC converter to work in the discharging direction when the DC bus voltage is lower than a third threshold value; the second DC / DC control unit controls the second DC / DC converter to work in the charging direction when the DC bus voltage is higher than a fourth threshold value; wherein the third threshold value is less than or equal to the fourth threshold value.

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