Energy equalization system and energy storage system

Abstract

The present application provides an energy equalization system and an energy storage system. The energy equalization system is arranged outside an energy storage device, and the energy balance system comprises at least two equalization circuits. In the same time period, a first equalization circuit is used for discharging a first energy storage unit, and a second equalization circuit is used for charging a second energy storage unit, thereby achieving energy equalization of the energy storage units in the energy storage device. Switching circuits arranged in the energy equalization system can realize the sharing of the equalization circuits between the energy storage units, thereby improving the utilization rate of the equalization circuits, and reducing energy equalization costs. Moreover, in the energy equalization system, equalization modules arranged in the energy storage units are replaced with the equalization circuits having large power, so that the energy equalization costs are reduced, the equalization power is increased, and the equalization 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 2, 2024, with application number 202410008089.X 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] Energy storage systems are currently expanding in scale. A single battery cluster in a mainstream commercial energy storage system typically requires over 400 cells connected in series. At the same time, the capacity of a single cell has exceeded 300Ah. Due to the large capacity and weight of a single battery cluster, energy storage system integrators typically design multiple battery packs within a single battery cluster. Battery pack capacity is affected by the dispersion of factory cell capacity, process variations, temperature control variations between battery packs, and varying cell degradation rates. During use, battery packs with poor state of health (SOH) performance can accelerate capacity degradation. Therefore, the industry is adding active balancing modules at the cell or pack level to mitigate the impact of poorly performing battery packs and increase the discharge capacity of the battery cluster over its lifecycle. Current active balancing solutions involve adding active balancing modules to each battery pack or cell. However, these active balancing modules have low utilization rates and high energy balancing costs. Summary of the Invention

[0005] The present application provides an energy balancing system and an energy storage system to improve the utilization rate of the active balancing function and reduce the energy balancing cost.

[0006] In a first aspect, an embodiment of the present application provides an energy balancing system, comprising: a first balancing circuit, a second balancing circuit, a first switching switch circuit, a second switching switch circuit, and a balancing bus. The first switching switch circuit is connected to the first side of the first balancing circuit, and the second side of the first balancing circuit is connected to the balancing bus; the second switching switch circuit is connected to the first side of the second balancing circuit, and the second side of the second balancing circuit is connected to the balancing bus. The first switching switch circuit and the second switching switch circuit are both used to connect the positive and negative poles of each energy storage unit connected in series in the energy storage device. When performing active energy balancing, the first switching switch circuit is used to connect the positive and negative poles of the first energy storage unit with the first side of the first balancing circuit, so that the first balancing circuit discharges the first energy storage unit; the second switching switch circuit is used to connect the positive and negative poles of the second energy storage unit with the first side of the second balancing circuit, so that the second balancing circuit charges the second energy storage unit.

[0007] The present application places the energy balancing system outside the energy storage device. The energy balancing system includes at least two balancing circuits. In the same time period, the first balancing circuit is used to discharge the first energy storage unit, and the second balancing circuit is used to charge the second energy storage unit, thereby achieving energy balancing of each energy storage unit in the energy storage device. Moreover, by using a switching circuit provided 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, using a higher-power balancing circuit in the energy balancing system to replace the balancing module provided in each energy storage unit can reduce the energy balancing cost, improve the balancing power, and shorten the balancing time.

[0008] In some embodiments of the present application, to achieve energy balancing, the average SOC value of each energy storage unit can be used as the target SOC value. The SOC value of the first energy storage unit is greater than the target SOC value, that is, the first energy storage unit is any energy storage unit with an SOC value greater than the target SOC value, and the SOC value of the second energy storage unit is less than the target SOC value, that is, the second energy storage unit is any energy storage unit with an SOC value less than the target SOC value. Using a first balancing circuit to charge the portion of energy in the first energy storage unit that exceeds the target SOC value to the second energy storage unit can achieve energy balancing.

[0009] In some embodiments of the present application, the energy balancing system may further include a balancing controller, which is used to control the on / off state of the first switching switch circuit and the second switching switch circuit, control the discharge state of the first balancing circuit, and control the charge state of the second balancing circuit. Specifically, the balancing controller can control the first switching switch circuit to connect the positive and negative poles of the discharge energy storage unit to the first side of the first balancing circuit, and control the second switching switch circuit to connect the positive and negative poles of the charge energy storage unit to the second balancing circuit. The first energy storage unit is any energy storage unit in the energy storage device whose SOC value is greater than the target SOC value, and the second energy storage unit is any energy storage unit in the energy storage device whose SOC value is less than the target SOC value. The balancing controller can also control the first balancing circuit to discharge the first energy storage unit, and control the second balancing circuit to charge the second energy storage unit.

[0010] In an embodiment of the present application, the first switching switch circuit specifically includes multiple pairs of first switches, and the number of pairs of first switches is the same as the number of energy storage units. One side of a pair of first switches is connected to the positive and negative output terminals of the corresponding energy storage unit, and the other side of a pair of first switches is connected to the positive and negative poles of the first side of the first balancing circuit. In the same time period, a pair of first switches is turned on and the other pairs of first switches are turned off. The first balancing circuit discharges the electrical energy of the first energy storage unit connected to the turned-on first switch to the balancing bus. Similarly, the second switching switch circuit includes multiple pairs of second switches, and the number of pairs of second switches is the same as the number of energy storage units. One side of a pair of second switches is connected to the positive and negative output terminals of the corresponding energy storage unit, and the other side of a pair of second switches is connected to the positive and negative poles of the first side of the second balancing circuit. In the same time period, a pair of second switches is turned on and the other pairs of second switches are turned off. The second balancing circuit charges the electrical energy on the balancing bus to the second energy storage unit connected to the turned-on second switch.

[0011] In some embodiments of the present application, when the SOC values ​​of multiple energy storage units in the energy storage device are all greater than the target SOC value, it can be considered that there are multiple energy storage units in the energy storage device that need to be discharged. When the SOC values ​​of multiple energy storage units in the energy storage device are all less than the target SOC value, it can be considered that there are multiple energy storage units in the energy storage device that need to be charged.

[0012] In an embodiment of the present application, during the energy balancing discharge process, within the same time period, the first switching circuit only connects the positive and negative electrodes of one energy storage unit, namely the first energy storage unit, so the first balancing circuit only discharges one energy storage unit, namely the first energy storage unit. When the difference between the SOC value of the first energy storage unit and the target SOC value is less than the first threshold value, indicating that the energy of the first energy storage unit has reached the balancing standard, the first switching circuit can be switched to connect the positive and negative electrodes of another energy storage unit, namely the third energy storage unit, to the first side of the first balancing circuit, so that the first balancing circuit discharges the third energy storage unit. The SOC value of the third energy storage unit is greater than the target SOC value.

[0013] In some embodiments of the present application, during the above-mentioned energy balancing discharge process, the discharge priority of each energy storage unit can be determined based on the difference between the SOC value of each energy storage unit and the target SOC value. For example, the greater the difference between the SOC value of an energy storage unit and the target SOC value, the higher the discharge priority of the energy storage unit, that is, the energy balancing operation is performed first. That is, in the above process, the difference between the SOC value of the first energy storage unit and the target SOC value is greater than the difference between the SOC value of the third energy storage unit and the target SOC value, so the first balancing circuit prioritizes discharging the first energy storage unit.

[0014] After all energy storage units with SOC values ​​greater than the target SOC value are discharged until the difference with the target SOC value is less than the first threshold, it means that these energy storage units have completed energy balancing. At this time, the first switching switch circuit can be switched to the disconnected state, that is, the first switching switch circuit will not connect any energy storage unit and the first side of the first balancing circuit.

[0015] In an embodiment of the present application, during the energy-balanced charging process, within the same time period, the second switching switch circuit only connects the positive and negative poles of one energy storage unit, namely the second energy storage unit, so the second balancing circuit only charges one energy storage unit, namely the second energy storage unit. When the difference between the SOC value of the second energy storage unit and the target SOC value is less than the second threshold value, it means that the energy of the second energy storage unit has reached the balancing standard, and the second switching switch circuit can be switched to connect the positive and negative poles of another energy storage unit, namely the fourth energy storage unit, to the first side of the second balancing circuit, so that the second balancing circuit charges the fourth energy storage unit. Wherein, the SOC value of the fourth energy storage unit is less than the target SOC value, and the second threshold value can be the same as the first threshold value or different, without limitation.

[0016] In some embodiments of the present application, during the above-mentioned energy-balancing charging process, the charging priority of each energy storage unit can be determined based on the difference between the SOC value of each energy storage unit and the target SOC value. For example, the greater the difference between the SOC value of an energy storage unit and the target SOC value, the higher the charging priority of the energy storage unit, that is, the energy-balancing operation is performed first. That is, in the above process, the difference between the SOC value of the second energy storage unit and the target SOC value is greater than the difference between the SOC value of the fourth energy storage unit and the target SOC value, so the second balancing circuit prioritizes discharging the second energy storage unit.

[0017] After each energy storage unit whose SOC value is less than the target SOC value is charged until the difference with the target SOC value is less than the second threshold, it means that these energy storage units have completed energy balancing. At this time, the second switching circuit can be switched to the disconnected state, that is, the second switching circuit will not connect any energy storage unit to the first side of the second balancing circuit.

[0018] In other embodiments of the present application, if the number of energy storage units connected in series in the energy storage device connected to the energy balancing system is large, in order to improve the active balancing power and active balancing efficiency, the number of balancing circuits in the energy balancing system can be appropriately increased.

[0019] For example, the energy balancing system may include multiple first balancing circuits and multiple first switching circuits, with the first switching circuits corresponding to the first balancing circuits. During a certain period of active balancing, to improve active balancing power and efficiency, the balancing controller may simultaneously control different first switching circuits to connect the positive and negative electrodes of different discharge energy storage units to the first sides of the corresponding first balancing circuits, and control the corresponding first balancing circuits to discharge the different first energy storage units. For example, during active balancing, two first switching circuits may be connected to two different first energy storage units respectively via two first switching circuits, and the two first balancing circuits may simultaneously discharge the energy stored in the two first energy storage units to the balancing bus. During another period of active balancing, if the required active balancing power and efficiency are lower, the balancing controller may also control only one first switching circuit to connect the positive and negative electrodes of one discharge energy storage unit to the first side of one first balancing circuit, and control the one first balancing circuit to discharge the one first energy storage unit.

[0020] For example, the energy balancing system may include multiple second balancing circuits and multiple second switching circuits, with the second switching circuits corresponding to the second balancing circuits. During a certain period of active balancing, to improve active balancing power and efficiency, the balancing controller may simultaneously control different second switching circuits to connect the positive and negative electrodes of different charging energy storage units to the first side of the corresponding second balancing circuit, and control the corresponding second balancing circuits to charge different first energy storage units. For example, during active balancing, two second switching circuits may be connected to two different second energy storage units respectively via two second switching circuits, and the two second balancing circuits may simultaneously discharge the energy stored in the two second energy storage units to the balancing bus. During another period of active balancing, if the required active balancing power and efficiency are lower, the balancing controller may also control only one second switching circuit to connect the positive and negative electrodes of one charging energy storage unit to the first side of one second balancing circuit, and control the one second balancing circuit to charge one second energy storage unit.

[0021] In the present application, in order to simplify the charge and discharge management control logic of the balancing controller for different energy storage units, the number of first balancing circuits included in the energy balancing system is generally the same as the number of second balancing circuits.

[0022] In some embodiments of the present application, the first balancing circuit and the second balancing circuit may include unidirectional DC-DC circuits. That is, the first balancing circuit only implements the discharge function, and the second balancing circuit only implements the charge function. Alternatively, in other embodiments of the present application, the first balancing circuit and the second balancing circuit may also include bidirectional DC-DC circuits. That is, the functions of the first balancing circuit and the second balancing circuit are interchangeable, and both the discharge function and the charge function can be implemented.

[0023] In some embodiments of the present application, the energy balancing system may be specifically configured as a balancing control box independent of the energy storage device.

[0024] In other embodiments of the present application, an energy storage controller, or battery control unit, may also be provided within the balancing control box, or energy balancing system. The energy storage controller is used to detect the SOC value of each energy storage unit. Specifically, it may perform power sampling via a battery sampling unit provided within each energy storage unit. The energy storage controller may determine a target SOC value based on the SOC value of each energy storage unit. The target SOC value may specifically be the average SOC value of each energy storage unit, also known as the median value. The energy storage controller may control the state of the energy storage device based on information such as the SOC value of each energy storage unit. For example, it may control the energy storage device to be in a charging state, a discharging state, or a static state. The energy storage controller may also determine the difference between the SOC value of each energy storage unit and the target SOC value. When certain differences are significant, such as greater than a certain threshold, indicating that the active balancing condition is met, the energy storage controller will initiate the active balancing process. The energy storage controller will determine the first and second energy storage units from each energy storage unit based on the target SOC value and transmit information about the first and second energy storage units to the balancing controller so that the balancing controller can perform active balancing operations. The first energy storage unit is an energy storage unit whose SOC value is greater than the target SOC value, and the second energy storage unit is an energy storage unit whose SOC value is less than the target SOC value.

[0025] In the second aspect, the present application provides an energy storage system, which may include any energy balancing system of possible design in the first aspect and an energy storage device, the energy storage device including a plurality of energy storage units connected in series, and the positive and negative poles of each energy storage unit are respectively connected to the first switching switch circuit and the second switching switch circuit in the energy balancing system.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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

[0030] Figure 1 is a schematic diagram of the structure of the energy storage system;

[0031] FIG2 is a schematic structural diagram of a battery cluster in the prior art;

[0032] FIG3 is a schematic diagram of the structure of battery pack-level energy balancing in the prior art;

[0033] FIG4 is a schematic diagram of a structure of an energy balancing system provided in an embodiment of the present application;

[0034] FIG5 is another schematic diagram of the structure of the energy balancing system provided in an embodiment of the present application;

[0035] FIG6 is a schematic diagram of the SOC values ​​of each energy storage unit provided in an embodiment;

[0036] FIG7 is a schematic diagram of the energy balancing process of the energy balancing system provided in an embodiment. DETAILED DESCRIPTION

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Referring to Figure 1, 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. Referring to Figure 2, a battery cluster can be specifically composed of one or more battery packs, which usually 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. For battery packs with different states of health (SOH) and states of charge (SOCs) in the battery cluster, in order to achieve the goal of simultaneously charging or discharging the battery packs, energy balancing between the battery packs is required, and this part of the work is completed by the battery balancing circuit. Referring to Figure 3 , the current active balancing solution at the battery pack level is as follows: a balancing unit (i.e., a battery balancing circuit) is added to 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, the balancing control unit controls the balancing units in the battery packs with a high state of charge to discharge to the balancing bus, while the balancing units in the battery packs with a low SOC draw power from the balancing bus. Ultimately, the SOCs of the battery packs are relatively consistent, and all battery packs are fully charged or discharged at the same time, thereby maximizing the utilization of the battery cluster.

[0042] The current active balancing solution at the battery pack level has the following shortcomings: 1. The balancing unit is deployed inside the battery pack. During the life cycle of the battery pack, since the differences in SOH and SOC between the battery packs in the early and middle stages are not obvious, most of the balancing units basically do not work in the early and middle stages of the energy storage system, resulting in a certain degree of resource waste. 2. Long-term non-operation of the balancing unit may cause reliability problems such as aging of devices and circuits. 3. The balancing unit is affected by the number of battery packs. As the number of battery packs increases, the cost increases accordingly, and the investment return is low. 4. The current energy storage system is mainly liquid-cooled. When the balancing unit inside the battery pack fails, the waterproof casing needs to be opened to replace the balancing unit. The maintenance workload is large and it brings sealing risks.

[0043] 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.

[0044] 4 , in an embodiment of the present application, the energy balancing system includes: a first balancing circuit, a second balancing circuit, a first switching switch circuit, a second switching switch circuit, and a balancing bus. The first switching switch circuit is connected to the first side of the first balancing circuit, and the second side of the first balancing circuit is connected to the balancing bus; the second switching switch circuit is connected to the first side of the second balancing circuit, and the second side of the second balancing circuit is connected to the balancing bus. Both the first switching switch circuit and the second switching switch circuit are used to connect the positive and negative poles of each energy storage unit connected in series in the energy storage device. When performing active energy balancing, the first switching switch circuit is used to connect the positive and negative poles of the first energy storage unit to the first side of the first balancing circuit, so that the first balancing circuit discharges the first energy storage unit; the second switching switch circuit is used to connect the positive and negative poles of the second energy storage unit to the first side of the second balancing circuit, so that the second balancing circuit charges the second energy storage unit.

[0045] Furthermore, to achieve energy balancing, the average SOC value of each energy storage unit can be used as the target SOC value. The SOC value of the first energy storage unit is greater than the target SOC value, i.e., the first energy storage unit is any energy storage unit with an SOC value greater than the target SOC value, and the SOC value of the second energy storage unit is less than the target SOC value, i.e., the second energy storage unit is any energy storage unit with an SOC value less than the target SOC value. Using the first balancing circuit to charge the portion of energy in the first energy storage unit that exceeds the target SOC value to the second energy storage unit can achieve energy balancing.

[0046] 4 , in some embodiments of the present application, the energy balancing system may further include a balancing controller, which is used to control the on / off state of the first switching switch circuit and the second switching switch circuit, control the discharge state of the first balancing circuit, and control the charge state of the second balancing circuit. Specifically, the balancing controller may control the first switching switch circuit to connect the positive and negative poles of the first energy storage unit to the first side of the first balancing circuit, and control the second switching switch circuit to connect the positive and negative poles of the second energy storage unit to the second balancing circuit, wherein the first energy storage unit is any energy storage unit in the energy storage device whose SOC value is greater than the target SOC value, and the second energy storage unit is any energy storage unit in the energy storage device whose SOC value is less than the target SOC value. The balancing controller may also control the first balancing circuit to discharge the first energy storage unit, and control the second balancing circuit to charge the second energy storage unit. Exemplarily, the balancing controller can be any one of a microcontroller unit (MCU), a central processing unit (CPU), a general-purpose processor, a digital signal processing (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., or a combination of any one or more other programmable logic devices, transistor logic devices, and hardware components.

[0047] The present application places the energy balancing system outside the energy storage device. The energy balancing system includes at least two balancing circuits. In the same time period, the first balancing circuit is used to discharge the first energy storage unit, and the second balancing circuit is used to charge the second energy storage unit, thereby achieving energy balancing of each energy storage unit in the energy storage device. Moreover, by using a switching circuit provided 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, using a higher-power balancing circuit in the energy balancing system to replace the balancing module provided in each energy storage unit can reduce the energy balancing cost, improve the balancing power, and shorten the balancing time.

[0048] In some embodiments of the present application, the first balancing circuit and the second balancing circuit may include unidirectional DC-DC circuits. That is, the first balancing circuit only implements the discharge function, and the second balancing circuit only implements the charge function. Alternatively, in other embodiments of the present application, the first balancing circuit and the second balancing circuit may also include bidirectional DC-DC circuits. That is, the functions of the first balancing circuit and the second balancing circuit are interchangeable, and both the discharge function and the charge function can be implemented.

[0049] In an embodiment of the present application, the first switching switch circuit specifically includes multiple pairs of first switches, and the number of pairs of first switches is the same as the number of energy storage units. One side of a pair of first switches is connected to the positive and negative poles of the corresponding energy storage unit, and the other side of a pair of first switches is connected to the positive and negative poles of the first side of the first balancing circuit. In the same time period, a pair of first switches is turned on and the other pairs of first switches are turned off. The first balancing circuit discharges the electrical energy of the first energy storage unit connected to the turned-on first switch to the balancing bus. Similarly, the second switching switch circuit includes multiple pairs of second switches, and the number of pairs of second switches is the same as the number of energy storage units. One side of a pair of second switches is connected to the positive and negative poles of the corresponding energy storage unit, and the other side of a pair of second switches is connected to the positive and negative poles of the first side of the second balancing circuit. In the same time period, a pair of second switches is turned on and the other pairs of second switches are turned off. The second balancing circuit charges the electrical energy on the balancing bus to the second energy storage unit connected to the turned-on second switch.

[0050] In some embodiments of the present application, when the SOC values ​​of multiple energy storage units in the energy storage device are all greater than the target SOC value, it can be considered that there are multiple energy storage units in the energy storage device that need to be discharged. When the SOC values ​​of multiple energy storage units in the energy storage device are all less than the target SOC value, it can be considered that there are multiple energy storage units in the energy storage device that need to be charged.

[0051] In an embodiment of the present application, during the energy balancing discharge process, within the same time period, the first switching circuit only connects the positive and negative electrodes of one energy storage unit, namely the first energy storage unit, so the first balancing circuit only discharges one energy storage unit, namely the first energy storage unit. When the difference between the SOC value of the first energy storage unit and the target SOC value is less than the first threshold value, indicating that the energy of the first energy storage unit has reached the balancing standard, the first switching circuit can be switched to connect the positive and negative electrodes of another energy storage unit, namely the third energy storage unit, to the first side of the first balancing circuit, so that the first balancing circuit discharges the third energy storage unit. The SOC value of the third energy storage unit is greater than the target SOC value.

[0052] In some embodiments of the present application, during the above-mentioned energy balancing discharge process, the discharge priority of each energy storage unit can be determined based on the difference between the SOC value of each energy storage unit and the target SOC value. For example, the greater the difference between the SOC value of an energy storage unit and the target SOC value, the higher the discharge priority of the energy storage unit, that is, the energy balancing operation is performed first. That is, in the above process, the difference between the SOC value of the first energy storage unit and the target SOC value is greater than the difference between the SOC value of the third energy storage unit and the target SOC value, so the first balancing circuit prioritizes discharging the first energy storage unit.

[0053] After all energy storage units with SOC values ​​greater than the target SOC value are discharged until the difference with the target SOC value is less than the first threshold, it means that these energy storage units have completed energy balancing. At this time, the first switching switch circuit can be switched to the disconnected state, that is, the first switching switch circuit will not connect any energy storage unit and the first side of the first balancing circuit.

[0054] In an embodiment of the present application, during the energy-balanced charging process, within the same time period, the second switching switch circuit only connects the positive and negative poles of one energy storage unit, namely the second energy storage unit, so the second balancing circuit only charges one energy storage unit, namely the second energy storage unit. When the difference between the SOC value of the second energy storage unit and the target SOC value is less than the second threshold value, it means that the energy of the second energy storage unit has reached the balancing standard, and the second switching switch circuit can be switched to connect the positive and negative poles of another energy storage unit, namely the fourth energy storage unit, to the first side of the second balancing circuit, so that the second balancing circuit charges the fourth energy storage unit. Wherein, the SOC value of the fourth energy storage unit is less than the target SOC value, and the second threshold value can be the same as the first threshold value or different, without limitation.

[0055] In some embodiments of the present application, during the above-mentioned energy-balancing charging process, the charging priority of each energy storage unit can be determined based on the difference between the SOC value of each energy storage unit and the target SOC value. For example, the greater the difference between the SOC value of an energy storage unit and the target SOC value, the higher the charging priority of the energy storage unit, that is, the energy-balancing operation is performed first. That is, in the above process, the difference between the SOC value of the second energy storage unit and the target SOC value is greater than the difference between the SOC value of the fourth energy storage unit and the target SOC value, so the second balancing circuit prioritizes discharging the second energy storage unit.

[0056] After each energy storage unit whose SOC value is less than the target SOC value is charged until the difference with the target SOC value is less than the second threshold, it means that these energy storage units have completed energy balancing. At this time, the second switching circuit can be switched to the disconnected state, that is, the second switching circuit will not connect any energy storage unit to the first side of the second balancing circuit.

[0057] In other embodiments of the present application, if the number of energy storage units connected in series in the energy storage device connected to the energy balancing system is large, in order to improve the active balancing power and active balancing efficiency, the number of balancing circuits in the energy balancing system can be appropriately increased.

[0058] For example, the energy balancing system may include multiple first balancing circuits and multiple first switching circuits, with the first switching circuits and first balancing circuits being arranged in a one-to-one correspondence. During a certain period of active balancing, to improve active balancing power and efficiency, the balancing controller may simultaneously control different first switching circuits to connect the positive and negative electrodes of different first energy storage units to the first sides of the corresponding first balancing circuits, and control the corresponding first balancing circuits to discharge the different first energy storage units. For example, during active balancing, two first switching circuits may be connected to two different first energy storage units respectively via two first switching circuits, and the two first balancing circuits may simultaneously discharge the energy stored in the two first energy storage units to the balancing bus. During another period of active balancing, if the required active balancing power and efficiency are lower, the balancing controller may also control only one first switching circuit to connect the positive and negative electrodes of one first energy storage unit to the first side of one first balancing circuit, and control the one first balancing circuit to discharge the one first energy storage unit.

[0059] For example, the energy balancing system may include multiple second balancing circuits and multiple second switching circuits, with the second switching circuits and second balancing circuits being arranged in a one-to-one correspondence. During a certain period of active balancing, to improve active balancing power and efficiency, the balancing controller may simultaneously control different second switching circuits to connect the positive and negative electrodes of different second energy storage units to the first side of the corresponding second balancing circuit, and control the corresponding second balancing circuits to charge the different second energy storage units. For example, during active balancing, two second switching circuits may be connected to two different second energy storage units respectively via two second switching circuits, and the two second balancing circuits may simultaneously discharge the energy stored in the two second energy storage units to the balancing bus. During another period of active balancing, if the required active balancing power and efficiency are lower, the balancing controller may also control only one second switching circuit to connect the positive and negative electrodes of one second energy storage unit to the first side of one second balancing circuit, and control the one second balancing circuit to charge the one second energy storage unit.

[0060] In the present application, in order to simplify the charge and discharge management control logic of the balancing controller for different energy storage units, the number of first balancing circuits included in the energy balancing system is generally the same as the number of second balancing circuits.

[0061] 4 , in some embodiments of the present application, the energy balancing system may be specifically configured as a balancing control box independent of the energy storage device.

[0062] Referring to Figure 5 , in some other embodiments of the present application, an energy storage controller, or battery control unit, may also be provided within the balancing control box, or energy balancing system. The energy storage controller is used to detect the SOC value of each energy storage unit. Specifically, it may perform power sampling via a battery sampling unit installed within each energy storage unit. The energy storage controller determines a target SOC value based on the SOC value of each energy storage unit. The target SOC value may specifically be the average SOC value of each energy storage unit, also known as the median value. The energy storage controller can control the state of the energy storage device based on information such as the SOC value of each energy storage unit. For example, it may control the energy storage device to be in a charging state, a discharging state, or a static state. The energy storage controller may also determine the difference between the SOC value of each energy storage unit and the target SOC value. When a certain difference is significant, such as greater than a third threshold, indicating that the active balancing condition is met, the energy storage controller initiates the active balancing process. The energy storage controller determines a first energy storage unit and a second energy storage unit from each energy storage unit based on the target SOC value and transmits information about the first and second energy storage units to the balancing controller, allowing the balancing controller to perform active balancing operations. The first energy storage unit is an energy storage unit whose SOC value is greater than the target SOC value, and the second energy storage unit is an energy storage unit whose SOC value is less than the target SOC value.

[0063] Exemplarily, the energy storage controller, i.e., the battery control unit, may be any one of a microcontroller unit (MCU), a general-purpose central processing unit (CPU), a general-purpose processor, a digital signal processing (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., or a combination of any one or more of other programmable logic devices, transistor logic devices, and hardware components.

[0064] The working process of the energy balancing system provided by this application is described below through a specific embodiment.

[0065] Referring to Figure 6, take the energy balancing system shown in Figure 4 connected to n energy storage units as an example. The energy storage controller detects that the SOC value of each energy storage unit is different. The SOC value of energy storage unit 1 is A1, the SOC value of energy storage unit 2 is A2, the SOC value of energy storage unit 3 is A3, the SOC value of energy storage unit n is An, and the target SOC value is A0. Energy storage unit 1 can discharge to the balancing bus through the first balancing circuit, with a total discharge capacity of A1-A0. At the same time, energy storage unit 3 can draw power from the balancing bus through the second balancing circuit, with a total power draw of A0-A3. Similarly, energy storage unit 2 and energy storage unit n draw power or supply power from the balancing bus according to the energy difference that needs to be balanced. And the state of energy balancing can be achieved in the charging state, static state or discharge state of the energy storage device.

[0066] Referring to FIG7 , the energy balancing process of the energy balancing system is as follows:

[0067] The energy storage controller detects the SOC value of each energy storage unit and determines that the target SOC value is A0. After that, the energy storage controller determines the difference between the SOC value of each energy storage unit and the target SOC value. It determines whether the active balancing condition is met. For example, when there are certain large differences, such as those greater than the third threshold, that is, the active balancing condition is met, the energy storage controller will start the active balancing process. Based on the target SOC value, the energy storage controller will determine that energy storage unit 1 and energy storage unit 2 are energy storage units that need to be discharged, and energy storage unit 3 and energy storage unit n are energy storage units that need to be charged, and send the above information to the balancing controller.

[0068] The balancing controller controls the first switching circuit to connect the output of energy storage unit 1 to the first balancing circuit, and controls the second switching circuit to connect energy storage unit 3 to the second balancing circuit. The first balancing circuit discharges energy storage unit 1 by A1-A0, and the second balancing circuit charges energy storage unit 4 by A0-A3.

[0069] When the balancing controller determines that A1-A0>A0-A3, energy storage unit 3 completes energy balancing before energy storage unit 1, that is, reaches the target SOC value. After energy storage unit 3 completes energy balancing but energy storage unit 1 has not completed energy balancing, the second switching circuit switches to conduct the output end of energy storage unit n and the second balancing circuit, so that the second balancing circuit starts charging energy storage unit n, while the first balancing circuit continues to discharge energy storage unit 1. When energy storage unit 1 is discharged to the target SOC value A0, the first switching circuit switches to conduct the output end of energy storage unit 2 and the first balancing circuit, so that the first balancing circuit starts discharging energy storage unit 2. After both energy storage unit 2 and energy storage unit n reach the target SOC value A0, the first switching circuit and the second switching circuit are disconnected, completing energy balancing.

[0070] When the balancing controller determines that A1 - A0 < A0 - A3, the energy storage unit 1 completes energy balancing before the energy storage unit 3, that is, reaches the target SOC value. Then, after the energy storage unit 1 completes energy balancing and the energy storage unit 3 has not completed energy balancing, the first switching circuit switches to conduct the output terminal of the energy storage unit 2 and the first balancing circuit, causing the first balancing circuit to start discharging the energy storage unit 2, while the second balancing circuit continues to charge the energy storage unit 3. When the energy storage unit 3 is charged to the target SOC value A0, the second switching circuit switches to conduct the output terminal of the energy storage unit n and the second balancing circuit, causing the second balancing circuit to start charging the energy storage unit n. After both the energy storage unit 2 and the energy storage unit n reach the target SOC value A0, the first switching switch circuit and the second switching switch circuit are disconnected, completing energy balancing.

[0071] Based on the same inventive concept, the present application also provides an energy storage system, which may include the above-mentioned energy balancing system provided by the embodiments of the present application and an energy storage device. The energy storage device includes a plurality of energy storage units connected in series, and the positive and negative electrodes of each energy storage unit are respectively connected to the first switching switch circuit and the second switching switch circuit in the energy balancing system.

[0072] The energy storage system provided by the embodiments of the present application can be a commercial power station energy storage system, or an industrial and commercial energy storage system, a household energy storage system, a power station energy storage, a charging station energy storage, etc. in scenarios with battery requirements. Moreover, the present application is applicable to various forms of batteries such as lithium-ion batteries, sodium-ion batteries, and magnesium-aluminum batteries.

[0073] In some embodiments of the present application, it can be applied to active balancing at the battery pack level. Correspondingly, the energy storage device can be a battery cluster, and the energy storage unit is a battery pack, that is, a plurality of battery packs connected in series form a battery cluster. The energy balancing system provided by the embodiments of the present application is external to the battery pack, and the energy balancing system can achieve energy balancing between battery packs.

[0074] In some other embodiments of the present application, it can be applied to active balancing at the cell level. Correspondingly, the energy storage device can be a battery pack, and the energy storage unit is a cell, that is, a plurality of cells connected in series form a battery pack. The energy balancing system provided by the embodiments of the present application is external to the cell, and the energy balancing system can achieve energy balancing between cells.

[0075] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. An energy balancing system for balancing the energy of a energy storage device, characterized in that The energy balancing system includes: a first balancing circuit, a second balancing circuit, a first switching circuit, a second switching circuit, and a balancing busbar; The first switching circuit is connected to the first side of the first balancing circuit, and the second side of the first balancing circuit is connected to the balancing busbar; The second switching circuit is connected to the first side of the second balancing circuit, and the second side of the second balancing circuit is connected to the balancing busbar; Both the first switching circuit and the second switching circuit are used to connect the positive and negative electrodes of each series-connected energy storage unit in the energy storage device; The first switching circuit is used to conduct the positive and negative electrodes of the first energy storage unit to the first side of the first balancing circuit, and the second switching circuit is used to conduct the positive and negative electrodes of the second energy storage unit to the first side of the second balancing circuit; the first balancing circuit is used to discharge the first energy storage unit, and the second balancing circuit is used to charge the second energy storage unit.

2. The energy balancing system according to claim 1, wherein The SOC value of the first energy storage unit is greater than the target SOC value, and the SOC value of the second energy storage unit is less than the target SOC value.

3. The energy balancing system according to claim 2, characterized in that, When the difference between the SOC value of the first energy storage unit and the target SOC value is less than a first threshold, the first switching circuit is used to conduct the positive and negative electrodes of the third energy storage unit to the first side of the first balancing circuit, and the first balancing circuit is used to discharge the third energy storage unit.

4. The energy balance system according to claim 3, wherein The SOC value of the third energy storage unit is greater than the target SOC value, and the difference between the SOC value of the first energy storage unit and the target SOC value is greater than the difference between the SOC value of the third energy storage unit and the target SOC value.

5. The energy balancing system according to any one of claims 2-4, characterized in that, When the difference between the SOC value of the second energy storage unit and the target SOC value is less than a second threshold, the second switching circuit is used to conduct the positive and negative electrodes of the fourth energy storage unit to the first side of the second balancing circuit, and the second balancing circuit is used to charge the fourth energy storage unit.

6. The energy balance system according to claim 5, wherein The SOC value of the fourth energy storage unit is less than the target SOC value, and the difference between the SOC value of the second energy storage unit and the target SOC value is greater than the difference between the SOC value of the fourth energy storage unit and the target SOC value.

7. The energy balancing system according to any one of claims 1-6, characterized in that, There are multiple first balancing circuits and first switching circuits. Different first switching circuits are used to conduct the positive and negative electrodes of different first energy storage units to the first side of the corresponding first balancing circuit, and different first balancing circuits are used to discharge different first energy storage units.

8. The energy balancing system according to any one of claims 1-7, characterized in that, There are multiple second balancing circuits and second switching circuits. Different second switching circuits are used to conduct the positive and negative electrodes of different second energy storage units to the first side of the corresponding second balancing circuit, and different second balancing circuits are used to charge different second energy storage units.

9. The energy balance system according to any one of claims 1-8, characterized in that, The first balancing circuit and the second balancing circuit include a unidirectional DCDC circuit, or, the first balancing circuit and the second balancing circuit include a bidirectional DCDC circuit.

10. The energy balance system according to any one of claims 1-9, characterized in that, It further includes: A balancing controller, which is used to control the on / off states of the first switching switch circuit and the second switching switch circuit, control the discharging state of the first balancing circuit, and control the charging state of the second balancing circuit.

11. The energy balancing system according to any one of claims 1-10, characterized in that, It further includes: An energy storage controller, which is used to detect the SOC values of the respective energy storage units, determine the target SOC value according to the SOC values of the respective energy storage units, and determine the first energy storage unit and the second energy storage unit among the respective energy storage units according to the target SOC value.

12. An energy storage system, characterized in that, It includes an energy storage device and the energy balancing system according to any one of claims 1-11. The energy storage device includes a plurality of energy storage units connected in series, and the positive and negative electrodes of each energy storage unit are respectively connected to the first switching switch circuit and the second switching switch circuit in the energy balancing system.

13. The energy storage system according to claim 12, 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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