Energy balancing system and energy storage system

Abstract

The present application provides an energy balancing system and an energy storage system. The energy balancing system is arranged outside an energy storage device; the energy balancing system comprises a switch circuit and a balancing circuit; the switch circuit enables electrical connection between positive and negative electrodes of a target energy storage unit and a first end of the balancing circuit, and the target energy storage unit is any energy storage unit in the energy storage device; and the balancing circuit is used for performing charging processing or discharging processing on the target energy storage unit. The switch circuit can achieve the sharing of the balancing circuit between the energy storage units, and improve the utilization rate of the balancing circuit. In addition, in the energy balancing system, a balancing circuit having relatively large power is used to replace a balancing module provided in each energy storage unit, so that costs can be reduced, the balancing power is improved, and the balancing time is shortened.

Description

Energy balancing system and energy storage system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on January 18, 2024, with application number 202410071106.4 and application name "An Energy Balancing System and Energy Storage System", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of energy technology, and in particular to an energy balancing system and an energy storage system. Background Art

[0004] In energy storage systems, multiple battery packs connected in series within a battery cluster can have inconsistent state of charge (SOC) values, leading to imbalanced state of charge (SOC) between the batteries during charging and discharging. This weak link between battery packs prevents maximum energy utilization within the battery cluster. To ensure simultaneous full charge of all battery packs during charging and maximum backup capacity during discharge, a balancing module is typically added to the output of each battery pack. This balancing module transfers energy from packs with higher SOC values ​​to packs with lower SOC values.

[0005] The balancing modules installed in the battery pack generally have low utilization rates and small energy transfer capabilities. As the number of battery packs increases, the number of balancing modules required also increases, resulting in increased costs and inconvenience in maintenance, which will increase the overall cost. Summary of the Invention

[0006] The present application provides an energy balancing system and an energy storage system to reduce energy balancing costs.

[0007] In a first aspect, an embodiment of the present application provides an energy balancing system, comprising: a switching circuit and a balancing circuit. The first end of the switching circuit is used to connect the positive and negative poles of a plurality of energy storage units connected in series in an energy storage device, the second end of the switching circuit is connected to the first end of the balancing circuit, and the second end of the balancing circuit is used to connect the positive and negative poles of the energy storage device. The switching circuit is used to connect the positive and negative poles of a target energy storage unit to the first end of the balancing circuit, and the target energy storage unit is any energy storage unit in the energy storage device. The balancing circuit is used to charge or discharge the target energy storage unit.

[0008] The present application places the energy balancing system outside the energy storage device. The energy balancing system only includes one balancing circuit. In the same time period, the target energy storage unit and the balancing circuit can be connected through the switching circuit. The balancing circuit is used to discharge or charge the target energy storage unit to achieve energy balancing of each energy storage unit in the energy storage device. And through the switching circuit set in the energy balancing system, the balancing circuit can be shared among the energy storage units, thereby improving the utilization rate of the balancing circuit and reducing the energy balancing cost. At the same time, a high-power balancing circuit is used in the energy balancing system to replace the balancing module set in each energy storage unit. Without affecting the active energy balancing function, the number of balancing modules can be reduced, the energy balancing cost can be reduced, and increasing the power of the balancing circuit can shorten the balancing time, improve the balancing efficiency, and quickly complete the balancing task issued by the system.

[0009] In an embodiment of the present application, when the target energy storage unit controlled by the switch circuit and connected to the balancing circuit is the energy storage unit with the largest SOC value among the energy storage units, or the target energy storage unit is any energy storage unit with an SOC value greater than the average value among the energy storage units, the balancing circuit is used to discharge the target energy storage unit. Specifically, the electric energy of the target energy storage unit that is higher than the average value of the energy storage units can be discharged to the entire energy storage device, that is, it can be considered that the energy storage device is charged by a single target energy storage unit. When the target energy storage unit controlled by the switch circuit and connected to the balancing circuit is the energy storage unit with the lowest SOC value among the energy storage units, or the target energy storage unit is any energy storage unit with an SOC value less than the average value among the energy storage units, the balancing circuit is used to charge the target energy storage unit. Specifically, the entire energy storage device can be used to charge the target energy storage unit.

[0010] In an embodiment of the present application, the energy storage device includes N energy storage units connected in series, wherein the positive and negative electrodes of each two energy storage units connected in series are connected, the positive electrode of the first energy storage unit serves as the positive electrode of the energy storage device, and the negative electrode of the Nth energy storage unit serves as the negative electrode of the energy storage device. In the present application, the N energy storage units connected in series may have N+1 ports, and the N+1 ports specifically include: the positive electrode of the first energy storage unit, the connection point between each two energy storage units connected in series, and the negative electrode of the Nth energy storage unit. By having two energy storage units connected in series share one port, the number of ports can be greatly reduced, thereby reducing the complexity of the connection relationship.

[0011] In some embodiments of the present application, the switching circuit may include a primary switch, a secondary switch, a first busbar, and a second busbar. The primary switch may include N+1 first switches, and the secondary switch may include a second switch, a third switch, a fourth switch, and a fifth switch. The N+1 first switches correspond one-to-one to the N+1 ports, and the first end of the i-th first switch is connected to the i-th port, where i is a positive integer less than or equal to N+1. That is, the first end of each first switch is used to connect to one of the N+1 ports, so that two energy storage units connected in series share the first end of one first switch. The second end of the j-th first switch is connected to the first busbar, where j is an odd number less than or equal to N+1, that is, the second ends of an odd number of first switches are connected to the first busbar. The second end of the k-th first switch is connected to the second busbar, where k is an even number less than or equal to N+1, that is, the second ends of an even number of first switches are connected to the second busbar, to ensure that the positive and negative poles of each energy storage unit can be connected to the first and second busbars respectively through the second ends of different first switches. The first end of the second switch is connected to the first bus, the first end of the third switch is connected to the second bus, and the second end of the second switch and the second end of the third switch are both connected to the positive terminal of the first end of the balancing circuit. In this way, by controlling the on and off of the second and third switches, the first bus or the second bus can be connected to the positive terminal of the balancing circuit. The first end of the fourth switch is connected to the first bus, the first end of the fifth switch is connected to the second bus, and the second end of the fourth switch and the second end of the fifth switch are both connected to the negative terminal of the first end of the balancing circuit. In this way, by controlling the on and off of the fourth and fifth switches, the first bus or the second bus can be connected to the negative terminal of the balancing circuit. The switch circuit can turn on the first switch connected to the positive and negative electrodes of the target energy storage unit; and when the voltage of the first bus is greater than the voltage of the second bus, turn on the second switch and the fifth switch; or when the voltage of the first bus is less than the voltage of the second bus, turn on the third switch and the fourth switch to connect the positive and negative electrodes of the target energy storage unit to the first end of the balancing circuit.

[0012] By setting a two-stage switch in the switching circuit, the positive and negative poles of different target energy storage units can be connected to the positive and negative poles of the first end of the balancing circuit respectively. The number of switches inside the switching circuit is small, which can reduce the control complexity and achieve fast switching.

[0013] In some embodiments of the present application, the energy balancing system generally also includes a controller for controlling the on / off states of switches in the switch circuit connected to the target energy storage unit to connect the positive and negative electrodes of the target energy storage unit to the first end of the balancing circuit. The controller can control the on / off states of each first switch, and based on the voltage levels of the first and second busbars, control the on / off states of the corresponding second to fifth switches to ensure that the positive electrode of the target energy storage unit is connected to the positive end of the first end of the balancing circuit, and the negative electrode of the target energy storage unit is connected to the negative end of the first end of the balancing circuit. Specifically, the controller can control the two first switches connected to the positive and negative electrodes of the target energy storage unit to be conductive. Thereafter, if the controller determines that the voltage of the first busbar is greater than the voltage of the second busbar, it can be assumed that the first busbar is conductive to the positive electrode of the target energy storage unit and the second busbar is conductive to the negative electrode of the target energy storage unit. In this case, the controller can turn on the second and fifth switches so that the first busbar is connected to the positive end of the first end of the balancing circuit and the second busbar is connected to the negative end of the first end of the balancing circuit. When the controller determines that the voltage of the first bus is less than the voltage of the second bus, it can be considered that the first bus is connected to the negative electrode of the target energy storage unit, and the second bus is connected to the positive electrode of the target energy storage unit. At this time, the third switch and the fourth switch can be turned on so that the second bus is connected to the positive terminal of the first end of the balancing circuit, and the first bus is connected to the negative terminal of the first end of the balancing circuit.

[0014] In some embodiments of the present application, the second end of the balancing circuit can be connected to the positive and negative poles of the energy storage device through a switch to prevent the energy storage device from leaking electricity to the energy balancing system when energy balancing is not required. Specifically, the switching circuit may further include a sixth switch and a seventh switch. The sixth switch is connected between the positive terminal of the second end of the balancing circuit and the first end of the first first switch among the N+1 first switches, and the first end of the first first switch is used to connect the positive pole of the first energy storage unit serving as the positive pole of the energy storage device; the seventh switch is connected between the negative terminal of the second end of the balancing circuit and the first end of the N+1th first switch among the N+1 first switches, and the first end of the N+1th first switch is used to connect the negative pole of the Nth energy storage unit serving as the negative pole of the energy storage device.

[0015] In an embodiment of the present application, when the energy balancing system is in operation, that is, when the balancing circuit is charging or discharging the target energy storage unit, the sixth switch and the seventh switch can be controlled to remain in the on state. When the balancing circuit stops charging or discharging the target energy storage unit, the sixth switch and the seventh switch can be controlled to be off.

[0016] In other embodiments of the present application, the second end of the balancing circuit can also be directly connected to the positive and negative electrodes of the energy storage device to simplify the switch structure of the switching circuit. Specifically, the positive end of the second end of the balancing circuit can be connected to the first end of the first first switch among the N+1 first switches, and the first end of the first first switch is used to connect to the positive electrode of the first energy storage unit serving as the positive electrode of the energy storage device; the negative end of the second end of the balancing circuit can be connected to the first end of the N+1th first switch among the N+1 first switches, and the first end of the N+1th first switch is used to connect to the negative electrode of the Nth energy storage unit serving as the negative electrode of the energy storage device.

[0017] In other embodiments of the present application, other switch structures may also be used to implement the switching function of the switch circuit. For example, N energy storage units connected in series may have 2N ports, specifically including: the positive electrode of each energy storage unit and the negative electrode of each energy storage unit. Accordingly, the switch circuit may include 2N switches, with the 2N switches corresponding one-to-one to the 2N ports. The first end of the i-th first switch is connected to the i-th port, where i is a positive integer less than or equal to 2N, i.e., the first end of each switch is used to connect to one of the 2N ports. The second end of the j-th first switch is connected to the positive end of the first end of the balancing circuit, where j is an odd number less than or equal to 2N, i.e., the second ends of the odd-numbered switches are connected to the positive end of the first end of the balancing circuit. The second end of the k-th switch is connected to the negative end of the first end of the balancing circuit, where k is an even number less than or equal to 2N, i.e., the second ends of the even-numbered switches are connected to the negative end of the first end of the balancing circuit. In this way, the positive and negative electrodes of each energy storage unit are connected to the positive and negative ends of the first end of the balancing circuit, respectively, through different switches. The switch circuit can conduct the switches connected to the positive and negative electrodes of the target energy storage unit to conduct the positive and negative electrodes of the target energy storage unit to the first end of the balancing circuit. Specifically, the controller can control the switches connected to the positive and negative electrodes of the target energy storage unit to conduct.

[0018] In some embodiments of the present application, the switching circuit and the balancing circuit can be provided on different circuit boards, that is, the switching circuit and the balancing circuit can be provided on two separate circuit boards. Alternatively, in other embodiments of the present application, the switching circuit and the balancing circuit can be integrated on the same circuit board to form an energy optimizer, thereby further reducing costs, reducing the size of the active balancing system, and improving integration.

[0019] In a second aspect, the present application provides an energy storage system, comprising any energy balancing system of possible design in the first aspect and an energy storage device, the energy storage device comprising a plurality of energy storage units connected in series, the positive and negative poles of each energy storage unit being respectively connected to the first end of the switching circuit in the energy balancing system, and the second end of the balancing circuit in the energy balancing system being connected to the positive and negative poles of the energy storage device.

[0020] The energy storage system provided in the embodiments of this application can be a commercial power station energy storage system, as well as an industrial and commercial energy storage system, a household energy storage system, a power station energy storage system, a charging station energy storage system, and other scenarios requiring batteries. Furthermore, this application is applicable to various types of batteries, including lithium-ion batteries, sodium-ion batteries, and magnesium-aluminum batteries.

[0021] In some embodiments of the present application, active balancing can be applied to the battery pack level. Accordingly, the energy storage device can be a battery cluster, and the energy storage unit is a battery pack, that is, multiple battery packs connected in series form a battery cluster. The energy balancing system provided in the embodiments of the present application is external to the battery pack, and the energy balancing system can achieve energy balancing between battery packs.

[0022] In other embodiments of the present application, active balancing at the cell level can be applied. Accordingly, the energy storage device can be a battery pack, and the energy storage unit is a battery cell, that is, multiple battery cells connected in series form a battery pack. The energy balancing system provided in the embodiments of the present application is external to the battery cell, and the energy balancing system can achieve energy balancing between the battery cells.

[0023] The technical effects that can be achieved by any possible design in the second aspect can be referred to the technical effects that can be achieved by any possible design in the first aspect, and will not be repeated here. These and other aspects of the present application will be more concise and easy to understand in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic diagram of the structure of battery pack-level energy balancing in the prior art;

[0025] FIG2 is a schematic diagram of the structure of an energy balancing system provided in an embodiment of the present application;

[0026] FIG3 is another schematic diagram of the structure of the energy balancing system provided in an embodiment of the present application;

[0027] FIG4 is another schematic diagram of the structure of the energy balancing system provided in an embodiment of the present application;

[0028] FIG5 is another schematic diagram of the structure of the energy balancing system provided in an embodiment of the present application;

[0029] FIG6 is a schematic diagram of energy balance provided in Example 1 of the present application;

[0030] FIG7 is a schematic diagram of energy balance provided in Example 2 of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0032] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "said", "above", "the", and "this" are intended to also include expressions such as "one or more", unless the context clearly indicates otherwise.

[0033] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0034] In addition, the same reference numerals in the figures represent the same or similar structures, and their repeated description will be omitted. The words expressing positions and directions described in this application are all explained by using the drawings as examples, but they can be changed as needed, and the changes made are included in the scope of protection of this application. The drawings in this application are only used to illustrate the relative position relationship and do not represent the actual scale.

[0035] Energy storage systems used in industry, commerce, or power stations generally include core components such as battery racks (BRs), battery management systems (BMSs), power conversion systems, energy management systems, and communication systems. A battery cluster can be composed of one or more battery packs, which typically include a cell group, a battery sampling unit, a battery balancing circuit, etc. The battery sampling unit and the battery control unit can form a battery management system, and the battery control unit can control the battery sampling unit to sample the power of the cell group. Battery packs have a short board effect during storage, transportation, and use, and the capacity of the battery cluster cannot be maximized. For battery packs with different states of health (SOH) and states of charge (SOC) in the battery cluster, in order to ensure that the battery packs can be fully charged or discharged at the same time, energy balancing between the battery packs is required. This part of the work is completed by the battery balancing circuit. Referring to Figure 1, the current active balancing solution for battery packs is to add a battery balancing circuit inside each battery pack. When the battery control unit determines that energy balancing is required between the battery packs based on the SOC values ​​of the cell groups in each battery pack obtained by the battery sampling unit, it controls the battery balancing circuits in the battery packs with high SOCs to discharge to the balancing bus, while the battery balancing circuits in the battery packs with low SOCs draw power from the balancing bus. Ultimately, the SOCs of the battery packs are relatively consistent, allowing each battery pack to be fully charged or discharged at the same time, thereby maximizing the utilization of the battery cluster. For example, assuming that the SOC of battery pack 2 in Figure 1 is higher than the average value and the SOC of battery pack 4 is lower than the average value, in order to ensure that the SOCs of the battery packs remain consistent, the energy of battery pack 2 can be transferred to battery pack 4 through battery balancing circuit 2, thereby achieving the purpose of simultaneous charging and discharging, thereby maximizing the backup power capacity of the battery cluster.

[0036] Current active pack-level balancing solutions have the following drawbacks: 1. Low cell balancing circuit utilization: To balance energy between battery packs, only two cell balancing circuits are required. If a battery cluster consists of four battery packs connected in series, the cell balancing circuit utilization is only 50%. If a battery cluster consists of eight battery packs connected in series, the utilization is only 25%. 2. Low energy transfer capability: Because the cell balancing circuits maintain a one-to-one correspondence with the battery packs, the power of the cell balancing circuits is generally low for cost and installation volume considerations. Assuming a balancing current of approximately 6A for current 280Ah and 314Ah cells, the balancing capability is too weak, resulting in a long time to adjust the SOC difference, requiring hours of balancing time. This increased energy transfer time also increases auxiliary power loss. 3. High number of components, high cost, and inconvenient maintenance: Because cell balancing circuits must be configured for each battery pack, the number of components increases, which in turn increases costs. This is especially true in power station energy storage scenarios with multiple battery packs, where the overall cost is even higher. Furthermore, a large number of cell balancing circuits also increases the failure rate.

[0037] In order to improve the utilization rate of the active balancing function and reduce the energy balancing cost, the present application provides an energy balancing system and an energy storage system. The energy balancing system and the energy storage system provided in the present application are described in detail below with reference to the accompanying drawings.

[0038] Referring to Figure 2, in an embodiment of the present application, the energy balancing system includes: a switching circuit and a balancing circuit. The first end of the switching circuit is used to connect the positive and negative poles of multiple energy storage units connected in series in the energy storage device, the second end of the switching circuit is connected to the first end of the balancing circuit, and the second end of the balancing circuit is used to connect the positive and negative poles of the energy storage device. The switching circuit is used to connect the positive and negative poles of the target energy storage unit to the first end of the balancing circuit, and the target energy storage unit is any energy storage unit in the energy storage device. The balancing circuit is used to charge or discharge the target energy storage unit.

[0039] The present application places the energy balancing system outside the energy storage device. The energy balancing system only includes one balancing circuit. In the same time period, the target energy storage unit and the balancing circuit can be connected through the switching circuit. The balancing circuit is used to discharge or charge the target energy storage unit to achieve energy balancing of each energy storage unit in the energy storage device. And through the switching circuit set in the energy balancing system, the balancing circuit can be shared among the energy storage units, thereby improving the utilization rate of the balancing circuit and reducing the energy balancing cost. At the same time, a high-power balancing circuit is used in the energy balancing system to replace the balancing module set in each energy storage unit. Without affecting the active energy balancing function, the number of balancing modules can be reduced, the energy balancing cost can be reduced, and increasing the power of the balancing circuit can shorten the balancing time, improve the balancing efficiency, and quickly complete the balancing task issued by the system.

[0040] In an embodiment of the present application, when the target energy storage unit controlled by the switch circuit and connected to the balancing circuit is the energy storage unit with the largest SOC value among the energy storage units, or the target energy storage unit is any energy storage unit with an SOC value greater than the average value among the energy storage units, the balancing circuit is used to discharge the target energy storage unit. Specifically, the electric energy of the target energy storage unit that is higher than the average value of the energy storage units can be discharged to the entire energy storage device, that is, it can be considered that the energy storage device is charged by a single target energy storage unit. When the target energy storage unit controlled by the switch circuit and connected to the balancing circuit is the energy storage unit with the lowest SOC value among the energy storage units, or the target energy storage unit is any energy storage unit with an SOC value less than the average value among the energy storage units, the balancing circuit is used to charge the target energy storage unit. Specifically, the entire energy storage device can be used to charge the target energy storage unit.

[0041] 2 , in an embodiment of the present application, the energy storage device includes N energy storage units connected in series, the positive and negative electrodes of each two energy storage units connected in series are connected, the positive electrode of the first energy storage unit serves as the positive electrode of the energy storage device, and the negative electrode of the Nth energy storage unit serves as the negative electrode of the energy storage device. In the present application, the N energy storage units connected in series can have N+1 ports, and the N+1 ports 1-n+1 specifically include: the positive electrode of the first energy storage unit, the connection point between each two energy storage units connected in series, and the negative electrode of the Nth energy storage unit. By having two energy storage units connected in series share one port, the number of ports can be greatly reduced, thereby reducing the complexity of the connection relationship.

[0042] 3 , in some embodiments of the present application, the switch circuit may include a primary switch, a secondary switch, a first busbar, and a second busbar. The primary switch may include N+1 first switches S1-Sn+1, and the secondary switch may include a second switch P2, a third switch P3, a fourth switch P4, and a fifth switch P5. The N+1 first switches S1-Sn+1 correspond one-to-one to the N+1 ports 1-n+1, ​​and the first end of the i-th first switch is connected to the i-th port, where i is a positive integer less than or equal to N+1. That is, the first end of each first switch is used to connect to one of the N+1 ports, so that two energy storage units connected in series share the first end of one first switch. The second end of the j-th first switch is connected to the first busbar, where j is an odd number less than or equal to N+1. That is, the second ends of an odd number of first switches are connected to the first busbar. The second end of the kth first switch is connected to the second busbar, where k is an even number less than or equal to N+1. That is, the second ends of an even number of first switches are connected to the second busbar, ensuring that the positive and negative poles of each energy storage unit can be connected to the first busbar and the second busbar, respectively, through the second ends of different first switches. For example, the positive pole of energy storage unit 1 is connected to the first busbar through first switch S1, and the negative pole of energy storage unit 1 is connected to the second busbar through first switch S2. The positive pole of energy storage unit 2 is connected to the second busbar through first switch S2, and the negative pole of energy storage unit 2 is connected to the first busbar through first switch S3, and so on. The first end of the second switch P2 is connected to the first busbar, the first end of the third switch P3 is connected to the second busbar, and the second end of the second switch P2 and the second end of the third switch P3 are both connected to the positive terminal of the first terminal of the balancing circuit. In this way, by controlling the on and off of the second switch P2 and the third switch P3, the first busbar or the second busbar can be connected to the positive terminal of the balancing circuit. The first end of the fourth switch P4 is connected to the first busbar, the first end of the fifth switch P5 is connected to the second busbar, and the second end of the fourth switch P4 and the second end of the fifth switch P5 are both connected to the negative terminal of the first terminal of the balancing circuit. In this way, by controlling the on and off of the fourth switch P4 and the fifth switch P5, the first busbar or the second busbar can be connected to the negative terminal of the first terminal of the balancing circuit. The switching circuit can turn on the first switch connected to the positive and negative electrodes of the target energy storage unit; and when the voltage of the first busbar is greater than the voltage of the second busbar, turn on the second switch and the fifth switch; or when the voltage of the first busbar is less than the voltage of the second busbar, turn on the third switch and the fourth switch to connect the positive and negative electrodes of the target energy storage unit to the first terminal of the balancing circuit.

[0043] By setting a two-stage switch in the switching circuit, the positive and negative poles of different target energy storage units can be connected to the positive and negative poles of the first end of the balancing circuit respectively. The number of switches inside the switching circuit is small, which can reduce the control complexity and achieve fast switching.

[0044] In some embodiments of the present application, the energy balancing system generally also includes a controller for controlling the on / off states of switches in the switch circuit connected to the target energy storage unit to connect the positive and negative electrodes of the target energy storage unit to the first end of the balancing circuit. Referring to Figure 3, the controller can control the on / off states of each first switch, and according to the voltage levels of the first busbar and the second busbar, control the on / off states of the corresponding second to fifth switches to ensure that the positive electrode of the target energy storage unit is connected to the positive end of the first end of the balancing circuit, and the negative electrode of the target energy storage unit is connected to the negative end of the first end of the balancing circuit. Specifically, the controller can control the first switch connected to the positive and negative electrodes of the target energy storage unit to be conductive. Thereafter, if the controller determines that the voltage of the first busbar is greater than the voltage of the second busbar, it can be assumed that the first busbar is conductive to the positive electrode of the target energy storage unit and the second busbar is conductive to the negative electrode of the target energy storage unit. At this time, the controller can turn on the second and fifth switches so that the first busbar is connected to the positive end of the first end of the balancing circuit and the second busbar is connected to the negative end of the first end of the balancing circuit. When the controller determines that the voltage of the first bus is less than the voltage of the second bus, it can be considered that the first bus is connected to the negative electrode of the target energy storage unit, and the second bus is connected to the positive electrode of the target energy storage unit. At this time, the third switch and the fourth switch can be turned on so that the second bus is connected to the positive terminal of the first end of the balancing circuit, and the first bus is connected to the negative terminal of the first end of the balancing circuit.

[0045] Referring to Figure 3, in some embodiments of the present application, the second end of the balancing circuit can be directly connected to the positive and negative electrodes of the energy storage device. Specifically, the positive end of the second end of the balancing circuit can be connected to the first end of the first first switch S1 among the N+1 first switches S1-Sn+1, and the first end of the first first switch S1 is used to connect to the positive electrode of the first energy storage unit 1, which serves as the positive electrode of the energy storage device; the negative end of the second end of the balancing circuit can be connected to the first end of the N+1th first switch Sn+1 among the N+1 first switches S1-Sn+1, and the first end of the N+1th first switch Sn+1 is used to connect to the negative electrode of the Nth energy storage unit n, which serves as the negative electrode of the energy storage device.

[0046] Referring to Figure 4, in some other embodiments of the present application, the second end of the balancing circuit can also be connected to the positive and negative electrodes of the energy storage device through a switch to prevent the energy storage device from leaking electricity into the energy balancing system when energy balancing is not required. Specifically, the switch circuit can further include a sixth switch K6 and a seventh switch K7. The sixth switch K6 is connected between the positive end of the second end of the balancing circuit and the first end of the first first switch S1 among the N+1 first switches S1-Sn+1, and the first end of the first first switch S1 is used to connect the positive electrode of the first energy storage unit 1, which serves as the positive electrode of the energy storage device; the seventh switch K7 is connected between the negative end of the second end of the balancing circuit and the first end of the N+1th first switch Sn+1 among the N+1 first switches S1-Sn+1, and the first end of the N+1th first switch Sn+1 is used to connect the negative electrode of the Nth energy storage unit n, which serves as the negative electrode of the energy storage device.

[0047] In the embodiment of the present application, when the energy balancing system is in operation, that is, when the balancing circuit is charging or discharging the target energy storage unit, the sixth switch K6 and the seventh switch K7 can be controlled to remain in the on state. When the balancing circuit stops charging or discharging the target energy storage unit, the sixth switch K6 and the seventh switch K7 can be controlled to be off.

[0048] 5 , in some other embodiments of the present application, other switch structures may be used to implement the switching function of the switch circuit. For example, N energy storage units connected in series may have 2N ports, and the 2N ports 1-2n specifically include: the positive electrode of each energy storage unit and the negative electrode of each energy storage unit. Accordingly, the switch circuit may include 2N switches T1-T2n, and the 2N switches T1-T2n correspond one-to-one to the 2N ports 1-2n. The first end of the i-th first switch is connected to the i-th port, where i is a positive integer less than or equal to 2N, that is, the first end of each switch is used to connect to one of the 2N ports. The second end of the j-th first switch is connected to the positive end of the first end of the balancing circuit, where j is an odd number less than or equal to 2N, that is, the second ends of the odd-numbered switches are connected to the positive end of the first end of the balancing circuit. The second end of the kth switch is connected to the negative terminal of the first end of the balancing circuit, where k is an even number less than or equal to 2N, that is, the second ends of an even number of switches are connected to the negative terminal of the first end of the balancing circuit, so that the positive and negative electrodes of each energy storage unit are respectively connected to the positive and negative electrodes of the first end of the balancing circuit through different switches. The switching circuit can turn on the switches connected to the positive and negative electrodes of the target energy storage unit to conduct the positive and negative electrodes of the target energy storage unit to the first end of the balancing circuit. Specifically, the controller can control the switches connected to the positive and negative electrodes of the target energy storage unit to conduct.

[0049] In some embodiments of the present application, the switching circuit and the balancing circuit can be provided on different circuit boards, that is, the switching circuit and the balancing circuit can be provided on two separate circuit boards. Alternatively, in other embodiments of the present application, the switching circuit and the balancing circuit can be integrated on the same circuit board to form an energy optimizer, thereby further reducing costs, reducing the size of the active balancing system, and improving integration.

[0050] The working process of the energy balancing system provided by this application is described below through two specific embodiments.

[0051] Example 1:

[0052] Referring to Figure 6, if the SOC value of the energy storage unit 2 in the energy storage device is higher than the average or the highest, in order for all energy storage units to be fully charged at the same time when the energy storage device is in the charging state, the SOC of the energy storage unit 2 needs to be reduced to be consistent with that of other energy storage units. At this time, it is necessary to connect the energy storage unit 2 to the balancing circuit through the switch circuit. First, the first switches S2 and S3 can be closed so that the positive electrode of the energy storage unit 2 is connected to the second bus and the negative electrode of the energy storage unit 2 is connected to the first bus. Then, the voltage of the first bus and the second bus is detected. When it is determined that the voltage of the first bus is less than the voltage of the second bus, the third switch P3 and the fourth switch P4 are closed so that the positive electrode of the energy storage unit 2 is connected to the positive terminal of the first end of the balancing circuit through the first switch S2, the second bus, and the third switch P3, and the negative electrode of the energy storage unit 2 is connected to the negative terminal of the first end of the balancing circuit through the first switch S3, the first bus, and the fourth switch P4. At this time, the sixth switch K6 and the seventh switch K7 are both in a closed state, allowing the balancing circuit to discharge the electrical energy stored in energy storage unit 2 to the positive and negative electrodes of the energy storage device, that is, using energy storage unit 2 to charge the energy storage device. When the SOC of energy storage unit 2 is consistent with the SOC of other energy storage units, or when energy storage unit 2 is discharged to the target value, the first switches S2 and S3, the third switch P3 and the fourth switch P4, the sixth switch K6 and the seventh switch K7 can be opened to complete energy balancing of the energy storage device.

[0053] Example 2:

[0054] Referring to Figure 7, if the SOC value of the energy storage unit 5 in the energy storage device is lower than the average or the lowest, in order for all energy storage units to be discharged simultaneously when the energy storage device is in the discharge state, the SOC of the energy storage unit 5 needs to be increased to be consistent with that of other energy storage units. At this time, it is necessary to connect the energy storage unit 5 to the balancing circuit through the switch circuit. First, the first switches S5 and S6 can be closed so that the positive electrode of the energy storage unit 5 is connected to the first bus and the negative electrode of the energy storage unit 5 is connected to the second bus. Then, the voltage of the first bus and the second bus is detected. When it is determined that the voltage of the first bus is greater than the voltage of the second bus, the second switch P2 and the fifth switch P5 are closed so that the positive electrode of the energy storage unit 5 is connected to the positive terminal of the first end of the balancing circuit through the first switch S5, the first bus, and the second switch P2, and the negative electrode of the energy storage unit 5 is connected to the negative terminal of the first end of the balancing circuit through the first switch S6, the second bus, and the fifth switch P4. At this time, the sixth switch K6 and the seventh switch K7 are both in a closed state, allowing the balancing circuit to charge the energy storage unit 2, that is, using the energy storage device to charge the energy storage unit 2. When the SOC of the energy storage unit 5 is consistent with the SOC of the other energy storage units, or when the energy storage unit 5 is charged to the target value, the first switches S5 and S6, the second switch P2 and the fifth switch P5, and the sixth switch K6 and the seventh switch K7 can be opened to complete energy balancing of the energy storage device.

[0055] Based on the same inventive concept, the present application provides an energy storage system, which may include the above-mentioned energy balancing system and an energy storage device provided in the embodiments of the present application. The energy storage device includes multiple energy storage units connected in series, and the positive and negative poles of each energy storage unit are respectively connected to the first end of the switching switch circuit in the energy balancing system, and the second end of the balancing circuit in the energy balancing system is connected to the positive and negative poles of the energy storage device.

[0056] The energy storage system provided in the embodiments of this application can be a commercial power station energy storage system, as well as an industrial and commercial energy storage system, a household energy storage system, a power station energy storage system, a charging station energy storage system, and other scenarios requiring batteries. Furthermore, this application is applicable to various types of batteries, including lithium-ion batteries, sodium-ion batteries, and magnesium-aluminum batteries.

[0057] In some embodiments of the present application, active balancing can be applied to the battery pack level. Accordingly, the energy storage device can be a battery cluster, and the energy storage unit is a battery pack, that is, multiple battery packs connected in series form a battery cluster. The energy balancing system provided in the embodiments of the present application is external to the battery pack, and the energy balancing system can achieve energy balancing between battery packs.

[0058] In other embodiments of the present application, active balancing at the cell level can be applied. Accordingly, the energy storage device can be a battery pack, and the energy storage unit is a battery cell, that is, multiple battery cells connected in series form a battery pack. The energy balancing system provided in the embodiments of the present application is external to the battery cell, and the energy balancing system can achieve energy balancing between the battery cells.

[0059] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. An energy balancing system, characterized in that, Comprising: A switching circuit and a balancing circuit; The first end of the switching circuit is used to connect the positive and negative electrodes of a plurality of energy storage units connected in series in the energy storage device, the second end of the switching circuit is connected to the first end of the balancing circuit, and the second end of the balancing circuit is used to connect the positive and negative electrodes of the energy storage device; The switching circuit is used to conduct the connection between the positive and negative electrodes of the target energy storage unit and the first end of the balancing circuit, and the target energy storage unit is any one of the energy storage units in the energy storage device; The balancing circuit is used to charge or discharge the target energy storage unit.

2. The energy balance system according to claim 1, wherein The energy storage device includes N energy storage units connected in series, and the N energy storage units connected in series have N + 1 ports, and the N + 1 ports include: the positive electrode of the first energy storage unit, the connection point between every two serially connected energy storage units, and the negative electrode of the Nth energy storage unit; The switching circuit includes a first-stage switch, a second-stage switch, a first bus bar and a second bus bar; The first-stage switch includes N + 1 first switches. Among them, the first end of the i-th first switch is connected to the i-th port, where i is a positive integer less than or equal to N + 1, the second end of the j-th first switch is connected to the first bus bar, and the second end of the k-th first switch is connected to the second bus bar, where j is an odd number less than or equal to N + 1, and k is an even number less than or equal to N + 1; The second-stage switch includes a second switch, a third switch, a fourth switch and a fifth switch. Among them, the first end of the second switch is connected to the first bus bar, the first end of the third switch is connected to the second bus bar, and the second ends of the second switch and the third switch are both connected to the positive electrode end of the first end of the balancing circuit; the first end of the fourth switch is connected to the first bus bar, the first end of the fifth switch is connected to the second bus bar, and the second ends of the fourth switch and the fifth switch are both connected to the negative electrode end of the first end of the balancing circuit.

3. The energy balance system according to claim 2, characterized in that, The switching circuit is used for: Conducting the first switches connected to the positive and negative electrodes of the target energy storage unit; When the voltage of the first bus bar is greater than the voltage of the second bus bar, conducting the second switch and the fifth switch; or, when the voltage of the first bus bar is less than the voltage of the second bus bar, conducting the third switch and the fourth switch.

4. The energy balancing system according to claim 3, wherein The energy balancing system further includes a controller, and the controller is used for: Controlling the conduction of the first switches connected to the positive and negative electrodes of the target energy storage unit; When the voltage of the first bus bar is greater than the voltage of the second bus bar, controlling the conduction of the second switch and the fifth switch; or, when the voltage of the first bus bar is less than the voltage of the second bus bar, controlling the conduction of the third switch and the fourth switch.

5. The energy balance system according to any one of claims 2-4, characterized in that, The switching circuit further includes a sixth switch and a seventh switch; The sixth switch is connected between the positive electrode of the second end of the equalization circuit and the first end of the first one of the N + 1 first switches, and the seventh switch is connected between the negative electrode of the second end of the equalization circuit and the first end of the (N + 1)-th first switch among the N + 1 first switches.

6. The energy balancing system according to claim 5, wherein The sixth switch and the seventh switch are used to conduct when the equalization circuit performs a charging process or a discharging process on the target energy storage unit, and to disconnect when the equalization circuit stops performing a charging process or a discharging process on the target energy storage unit.

7. The energy balance system according to any one of claims 2-4, characterized in that, The positive electrode of the second end of the equalization circuit is connected to the first end of the first one of the N + 1 first switches, and the negative electrode of the second end of the equalization circuit is connected to the first end of the (N + 1)-th first switch among the N + 1 first switches.

8. The energy balancing system according to claim 1, wherein The energy storage device includes N energy storage units connected in series, and the N energy storage units connected in series have 2N ports, and the 2N ports include: the positive electrode of each energy storage unit and the negative electrode of each energy storage unit; The switch circuit includes 2N switches. Among them, the first end of the i-th first switch is connected to the i-th port, where i is a positive integer less than or equal to 2N. The second end of the j-th first switch is connected to the positive electrode of the first end of the equalization circuit, and the second end of the k-th switch is connected to the negative electrode of the first end of the equalization circuit, where j is an odd number less than or equal to 2N, and k is an even number less than or equal to 2N.

9. The energy balance system according to claim 8, wherein The switch circuit is used for: Conducting the switches connected to the positive electrode and the negative electrode of the target energy storage unit.

10. The energy balancing system according to claim 9, characterized in that, The energy equalization system further includes a controller, and the controller is used for: Controlling the switches connected to the positive electrode and the negative electrode of the target energy storage unit to conduct.

11. The energy balancing system according to any one of claims 1-10, characterized in that, The switch circuit and the equalization circuit are arranged on different circuit boards; or, the switch circuit and the equalization circuit are integrated on the same circuit board.

12. The energy balancing system according to any one of claims 1-11, characterized in that, The target energy storage unit is the energy storage unit with the largest SOC value among the energy storage units, and the equalization circuit is used to perform a discharging process on the target energy storage unit; or, the target energy storage unit is the energy storage unit with the lowest SOC value among the energy storage units, and the equalization circuit is used to perform a charging process on the target energy storage unit.

13. An energy storage system, characterized in that, Including an energy storage device and the energy equalization system according to any one of claims 1-12, the energy storage device includes a plurality of energy storage units connected in series, the positive and negative electrodes of each energy storage unit are respectively connected to the first end of the switch circuit in the energy equalization system, and the second end of the equalization circuit in the energy equalization system is connected to the positive and negative electrodes of the energy storage device.

14. The energy storage system according to claim 13, wherein The energy storage device is a battery cluster, and the energy storage unit is a battery pack; or, the energy storage device is a battery pack, and the energy storage unit is a battery cell.

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