Active equalization circuit of flow battery

Abstract

The utility model relates to an active equalization circuit of a flow battery. The active equalization circuit comprises a flow battery pack, a PCS converter, an equalizer converter and a power distribution unit, the PCS converter is connected to two ends of the liquid flow battery pack and is used for charging and discharging the liquid flow battery pack; the flow battery pack comprises a plurality of flow battery modules, and each flow battery module comprises a plurality of sub-modules; and the equalizer converter is connected with the flow battery pack through the battery pack change-over switch and the power distribution unit and is used for equalizing the flow battery sub-modules. Through the arrangement of the equalizer converter and the power distribution unit, the efficient and flexible distribution of energy among the multi-flow batteries is realized, and the circuit structure is simplified; through real-time monitoring and dynamic adjustment of the main control system, changes of energy requirements can be quickly responded, SOC balance among different sub-modules in the flow battery is ensured, the problem of energy imbalance caused by uneven charging and discharging is effectively solved, and the overall performance and stability of the system are improved.

Description

Technical Field

[0001] This utility model relates to the field of flow battery balancing technology, specifically to an active balancing circuit for flow batteries. Background Technology

[0002] Flow batteries, as an energy storage technology, have shown great potential in large-scale energy storage due to their advantages such as long lifespan, rapid response, and ease of scalability. However, in practical applications, flow batteries face a key challenge: differences in charge-discharge rates and efficiencies between different electrolyte storage tanks lead to uneven energy distribution. This imbalance not only reduces the overall performance of the battery but can also cause localized overheating or overcharging / discharging, thereby shortening the battery's lifespan. To address this issue, current solutions typically equip each battery pack with multiple power electronic devices, such as DC / DC converters, to achieve balanced energy distribution. However, this approach not only increases system complexity and cost but also results in a large space occupation and high maintenance difficulty, limiting the application of flow batteries in more scenarios. Utility Model Content

[0003] To solve the above problems, this utility model provides an active balancing circuit for a flow battery, comprising:

[0004] Flow battery pack, PCS converter, equalizer converter, and power distribution unit; among which:

[0005] The flow battery pack includes at least two flow battery modules, and each flow battery module includes multiple sub-modules;

[0006] The PCS converter is connected to both ends of the flow battery pack to charge and discharge the flow battery pack;

[0007] One end of the equalizer converter is connected to the AC power grid, and the other end is connected to the corresponding power distribution unit through the battery pack switching switch. The power distribution unit is connected to the flow battery module.

[0008] The power distribution unit includes multiple switching switches, which control the current flow to the corresponding sub-module.

[0009] Based on the above scheme, the DC port of the equalizer converter selects the corresponding flow battery module for equalization through the first battery pack switching switch or the second battery pack switching switch.

[0010] Based on the above scheme, the switching switches of the power distribution unit are respectively connected to the flow battery sub-modules. At any given time, only one set of switches is closed. The flow battery pack has multiple sub-modules, and each sub-module corresponds to a set of switching switches of the power distribution unit.

[0011] Based on the above scheme, it also includes a main control system. The main control system monitors the SOC of the flow battery sub-module in real time and connects the equalizer converter to the module with the lowest or highest SOC through the distribution unit to perform charging or discharging operations.

[0012] Based on the above scheme, the main control system determines the maximum and minimum SOC difference of the flow battery sub-modules in the battery pack in real time, and performs equalization on the flow battery pack with the largest SOC difference among the flow battery sub-modules.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: by setting up the equalizer converter and power distribution unit, the energy distribution among multiple flow batteries is efficient and flexible, simplifying the circuit structure; through the real-time monitoring and dynamic adjustment of the main control system, it can quickly respond to changes in energy demand, ensure the balance of SOC among different sub-modules inside the flow battery, effectively solve the energy imbalance problem caused by uneven charging and discharging, and improve the overall performance and stability of the system. Attached Figure Description

[0014] Figure 1 A schematic diagram of the active equalization circuit provided in this application;

[0015] Figure 2 Another active equalization circuit diagram provided in this application;

[0016] Figure 3 A schematic diagram of the power distribution unit structure provided in this application; Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings:

[0018] like Figure 1 As shown, this application provides one embodiment, including:

[0019] First flow battery pack 1, second flow battery pack 2, first PCS (Power Conversion System) converter 3, second PCS converter 4, and SOC (Power Conversion System) equalizer 5;

[0020] The first PCS converter 3 and the second PCS converter 4 are respectively connected to the two ends of the first flow battery pack 1 and the second flow battery pack 2, and are used to charge and discharge the first flow battery pack 1 and the second flow battery pack 2.

[0021] When charging the battery pack, the PCS converter converts the AC power from the grid into DC power.

[0022] During the use of flow batteries, the energy balance problem caused by uneven charging and discharging between different flow tanks seriously affects the normal operation of the flow batteries. Based on this, this application configures a SOC equalizer 5 in the circuit, including an equalizer converter 51 and a corresponding power distribution unit. The equalizer converter is connected to the AC mains, and the DC port selects the corresponding battery pack for equalization via battery pack switching switches P1, N1 or P2, N2. Furthermore, the power distribution unit is connected to different flow battery sub-modules.

[0023] Specifically, the equalizer converter is connected to the corresponding first power distribution unit 52 and the first flow battery pack through battery pack switching switches P1 and N1;

[0024] The equalizer converter is connected to the corresponding second power distribution unit 53 and the second flow battery pack via battery pack switching switches P2 and N2.

[0025] Because the energy balance problem caused by uneven charging and discharging between different flow battery packs seriously affects the normal use of flow batteries, this application configures an equalization converter and a corresponding power distribution unit. By judging the SOC of each battery in the battery pack in real time through the main control system, the state of the power distribution unit and the battery pack switching switch is adjusted to achieve SOC balance.

[0026] The first flow battery pack and the second flow battery pack each contain multiple flow battery modules, each flow battery module contains multiple sub-modules, and each sub-module contains one or more battery cells.

[0027] According to one embodiment, such as Figure 2 As shown, the first flow battery pack 1 includes a first module, a second module and a third module, and the second flow battery pack includes a fourth module, a fifth module and a sixth module. Each module is divided into sub-module A and sub-module B, and the two ends of the battery in each sub-module are connected to the power distribution unit respectively.

[0028] According to this embodiment, by combining four battery pack switching switches and two power distribution units, a specific submodule can be charged or discharged.

[0029] Power distribution unit such as Figure 3 As shown, the first power distribution unit is equipped with switching switches corresponding to the sub-modules. Each sub-module is connected to a switching switch at both ends. For example, A1 and A2 are connected to the two ends of sub-module A in the first module, and B1 and B2 are connected to the two ends of sub-module B in the first module. There are a total of 12 switching switches, namely A1~A6 and B1~B6. Each group of switches is connected to one sub-module, and at any given time, at most only one group of switches is closed. The second power distribution unit is the same as the first power distribution unit.

[0030] This application also includes a main control system capable of real-time monitoring of the SOC of the flow battery submodules and electrically connecting the equalizer converter to the module with the lowest or highest SOC via a distribution unit for charging or discharging operations. The main control system can also determine the maximum and minimum SOC difference between the flow battery submodules in the first flow battery pack 1 and the second flow battery pack 2 in real time. Once equalization is required, the main control system controls the switching switch and power distribution unit to connect the equalizer converter to the submodule with the largest SOC difference for equalization, thereby achieving flexible energy distribution and efficient equalization.

[0031] Furthermore, the main control system selects the high SOC submodule (denoted as submodule A) that needs to be discharged and the low SOC submodule (denoted as submodule B) that needs to be charged, and performs discharge and charging operations on A and B respectively, as follows:

[0032] Discharge operation: Close the battery pack switching switch (P1, N1) and the power distribution unit switching switch (A1, B1) connected to submodule A to connect the equalizer converter to submodule A; start the equalizer converter to convert the DC power of submodule A into AC power and transmit it to the external power grid or load; when the SOC value of submodule A drops to a certain level, disconnect the switching switch to stop discharging.

[0033] Charging operation: Close the battery pack switching switch (P1, N1) and the power distribution unit switching switch (A2, B2) connected to submodule B to connect the equalizer converter to submodule B; the equalizer converter obtains power from the external power grid or load and converts it into DC power, which is then transmitted to submodule B for charging; when the SOC value of submodule B rises to a certain level, the switching switch is opened to stop charging.

[0034] During charging and discharging, the main control system monitors the SOC value of the submodules in real time to ensure safe and stable charging and discharging. The circuit in this application solves the energy imbalance problem caused by uneven charging and discharging between different submodules within the flow battery system through equalization operation. It can also replenish the system with energy from an external power source when needed, ensuring efficient and stable operation of the system.

[0035] In summary, the active balancing circuit for flow batteries provided by this invention, compared to traditional methods that rely on multiple independent power electronic devices, such as bidirectional DC / DC converters, requiring dedicated equipment for each pair of flow tanks, resulting in a complex system structure and numerous components, significantly simplifies the system structure and reduces the number of required devices by introducing a unified equalizer converter combined with a power distribution unit. This reduces system complexity; furthermore, the power distribution unit dynamically adjusts energy distribution, rapidly responding to changes in energy demand and improving system flexibility and adaptability.

[0036] The foregoing has shown and described the basic principles and main features of this utility model. It is obvious to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments. Therefore, the embodiments should be regarded as exemplary and non-limiting. The scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalents of the claims within this utility model.

[0037] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An active balancing circuit for a flow battery, characterized in that, include: Flow battery pack, PCS converter, equalizer converter, and power distribution unit; among which: The flow battery pack includes at least two flow battery modules, and each flow battery module includes multiple sub-modules; The PCS converter is connected to both ends of the flow battery pack to charge and discharge the flow battery pack; One end of the equalizer converter is connected to the AC power grid, and the other end is connected to the corresponding power distribution unit through the battery pack switching switch. The power distribution unit is connected to the flow battery module. The power distribution unit includes multiple switching switches, which control the current flow to the corresponding sub-module.

2. The active balancing circuit for a flow battery according to claim 1, characterized in that, The equalizer converter DC port selects the corresponding flow battery module for equalization via a first battery pack switching switch or a second battery pack switching switch.

3. The active balancing circuit for a flow battery according to claim 1, characterized in that, The switching switches of the power distribution unit are respectively connected to the flow battery sub-modules. At any given time, only one set of switches is closed. The flow battery pack has multiple sub-modules, and each sub-module corresponds to a set of switching switches of the power distribution unit.

4. The active balancing circuit for a flow battery according to claim 1, characterized in that, It also includes a main control system, which monitors the SOC of the flow battery sub-modules in real time and connects the equalizer converter to the module with the lowest or highest SOC through the distribution unit to perform charging or discharging operations.

5. The active balancing circuit for a flow battery according to claim 4, characterized in that, The main control system determines the maximum and minimum SOC difference of the flow battery sub-modules in the battery pack in real time, and performs equalization on the flow battery pack with the largest SOC difference.

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