Energy storage battery pack and energy storage system

Abstract

The utility model provides an energy storage battery pack and an energy storage system, the energy storage battery pack comprises a power converter, a battery management system and a plurality of battery modules which are connected in series, and each battery module comprises a change-over switch module and a battery cell which are electrically connected. The battery modules connected in series are integrally connected to the direct current bus through the power converter, that is, a single battery pack does not need to be connected with the other battery packs in series and then connected to the direct current bus, so that when a certain battery module works abnormally, the battery module can be cut off from the battery pack through the change-over switch module, and the work of the other battery modules is not influenced; and the whole battery pack can be cut off from the system through the power converter, so that the control flexibility of the battery pack can be improved, and the utilization rate and the stability of the system capacity can be improved.

Description

Technical Field

[0001] This utility model relates to the field of energy storage technology, and in particular to an energy storage battery pack and energy storage system. Background Technology

[0002] With the development of new energy technologies, the installed capacity of new energy power generation continues to reach new highs. To overcome the severe intermittency of large-scale new energy power generation, the demand for energy storage is also increasing. Among them, battery energy storage has seen rapid development on both the power generation and consumption sides due to its flexibility, controllability, and energy density.

[0003] Because individual batteries have low voltages, the industry practice is to connect many batteries in series to form a battery pack, then connect multiple battery packs in series to form a battery cluster, and finally connect multiple battery clusters in parallel via DC / AC or DC / DC converters to achieve energy exchange between the energy storage batteries and the AC / DC grid in large-scale energy storage. In the pure series mode, all batteries in the same battery cluster have the same charging and discharging current and time, and minor differences between batteries are adjusted by balancing circuits (such as passive balancing circuits). However, as the service life increases, the differences between batteries become more pronounced, and passive balancing leads to significant energy waste and heat generation problems. Furthermore, to ensure the safe and usable use of any battery pack within a single battery cluster, the limitations of the bottleneck battery pack must be considered, requiring derating of the entire battery cluster, resulting in even more energy waste. Utility Model Content

[0004] This invention provides an energy storage battery pack and an energy storage system, aiming to solve the problem of low battery control flexibility and energy waste caused by series-structured battery clusters in related technologies.

[0005] To address the aforementioned technical problems, the present invention provides an energy storage battery pack, comprising: a power converter, a battery management system, and multiple battery modules connected in series. Each battery module includes an electrically connected switching module and battery cells. The power converter is electrically connected to the switching modules in the first and last battery modules and is used for electrical connection to an external DC bus. The battery management system is electrically connected to the battery modules and the power converter and is used for electrical connection to an external control bus.

[0006] Further, the switching module includes a first switching device and a second switching device; the first end of the first switching device is electrically connected to the positive terminal of the battery cell, and the second end of the first switching device is electrically connected to the battery management system; in the first switching module, the third end of the first switching device is electrically connected to the power converter and the first end of the second switching device, respectively; in the remaining switching modules, the third end of the first switching device is electrically connected to the first end of the second switching device; the second end of the second switching device is electrically connected to the battery management system; in the last switching module, the third end of the second switching device is electrically connected to the negative terminal of the battery cell and the power converter, respectively; in the remaining switching modules, the third end of the second switching device is electrically connected to the negative terminal of the battery cell and the first end of the second switching device in the next switching module, respectively.

[0007] Furthermore, both the first switching device and the second switching device include any one of the following: a relay and a field-effect transistor.

[0008] Furthermore, the battery management system includes a sampling module, an equalization module, a control module, and a communication module; the sampling module is electrically connected to the battery module, the equalization module, and the control module respectively; the communication module is electrically connected to the control module and is used to electrically connect to the control bus; the control module is also electrically connected to the equalization module, the switching module, and the power converter; the equalization module is also connected to the sampling module, or the equalization module is also electrically connected to the battery module.

[0009] Furthermore, the equalization module includes any one of the following: an active equalization circuit or a passive equalization circuit.

[0010] Furthermore, the power converter includes a single-stage isolated DC / DC converter or a two-stage isolated DC / DC converter.

[0011] Furthermore, the isolated DC / DC converter includes any of the following: DAB converter, CLLC converter, and Buck-LLC converter.

[0012] Furthermore, the isolated DC / DC converter is a DAB converter, which includes a first H-bridge circuit, a second H-bridge circuit, and a transformer; the first and second terminals of the first H-bridge circuit are both electrically connected to the DC bus, and the third and fourth terminals of the first H-bridge circuit are both electrically connected to the transformer; the first and second terminals of the second H-bridge circuit are both electrically connected to the transformer, and the third and fourth terminals of the second H-bridge circuit are both electrically connected to the battery module.

[0013] Furthermore, the energy storage battery pack also includes an auxiliary power supply, which is electrically connected to the battery management system, the switching module and the power converter, and is used to electrically connect to the control bus.

[0014] The second aspect of this utility model provides an energy storage system, including a plurality of energy storage battery packs as described in the first aspect of this utility model, wherein the plurality of energy storage battery packs are all connected in parallel with a DC bus.

[0015] As described above, the energy storage battery pack of this invention includes multiple battery modules. The cells in each battery module are connected in series via a switching module, which increases the overall voltage of the battery pack. The series-connected battery modules are then connected to the DC bus via a power converter. In other words, a single battery pack is directly connected to the DC bus without needing to be connected in series with other battery packs. Therefore, if a battery module malfunctions, it can be disconnected from the battery pack via the switching module without affecting the operation of the remaining battery modules. Since the voltage gain change caused by disconnecting a few malfunctioning battery modules is relatively small, and the battery management system manages their charging and discharging, the power converter does not require an extremely wide input voltage range, simplifying the converter's design. Furthermore, the entire battery pack can be disconnected from the system via the power converter, thereby improving the system's capacity utilization and stability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the first type of energy storage battery pack according to an embodiment of the present utility model;

[0017] Figure 2 This is a schematic diagram of the structure of a second type of energy storage battery pack according to an embodiment of the present utility model;

[0018] Figure 3 This is a schematic diagram of the structure of a third type of energy storage battery pack according to an embodiment of this utility model;

[0019] Figure 4 This is a schematic diagram of the structure of a power converter according to an embodiment of the present utility model;

[0020] Figure 5 This is a schematic diagram of the structure of an energy storage system according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Throughout the description, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Furthermore, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0022] In related technologies, the low flexibility of battery control in series-connected battery clusters leads to energy waste. Therefore, this utility model provides an energy storage battery pack.

[0023] like Figure 1 The diagram shows a first type of energy storage battery pack provided in this embodiment of the present invention. The energy storage battery pack includes a power converter, a battery management system, and multiple battery modules connected in series. Each battery module includes a switching module and a battery cell that are electrically connected. The power converter is electrically connected to the switching modules in the first battery module and the last battery module, and is used to be electrically connected to an external DC bus. The battery management system is electrically connected to the battery modules and the power converter, and is used to be electrically connected to an external control bus.

[0024] Specifically, in this embodiment, a single energy storage battery pack includes multiple battery modules. The cells in each battery module are connected in series via a switching module, thereby increasing the overall voltage of the single battery pack. The series-connected battery modules are then connected to the DC bus via a power converter. In other words, a single battery pack is directly connected to the DC bus without needing to be connected in series with other battery packs. Therefore, when a cell in a battery module malfunctions, it can be disconnected from the battery pack via the switching module, for example, by bypassing it, without affecting the operation of the remaining battery modules. Alternatively, the entire battery pack can be disconnected directly via the power converter. Since the battery pack is directly connected to the DC bus via the power converter, disconnecting a single battery pack will not affect the operation of the remaining battery packs, thus improving the flexibility of battery pack control and consequently enhancing the system's capacity utilization and stability. Furthermore, because the voltage gain variation caused by disconnecting a few malfunctioning battery modules is relatively small, and the battery management system manages the charging and discharging of each battery module, the power converter does not require an extremely wide input voltage range, simplifying the converter's design structure. In addition, the battery pack is connected to the control bus, which enables communication between the battery pack and the host computer system. When there are multiple battery packs, communication between the battery packs facilitates the management and control of the battery packs.

[0025] like Figure 2The diagram shown is a structural schematic of the second type of energy storage battery pack provided in this embodiment. Please refer to [link / reference]. Figure 2 The switching module includes a first switching device K1 and a second switching device K2. The first terminal of the first switching device K1 is electrically connected to the positive terminal of the battery cell, and the second terminal of the first switching device K1 is electrically connected to the battery management system. In the first switching module, the third terminal of the first switching device K1 is electrically connected to the power converter and the first terminal of the second switching device K2, respectively. In the remaining switching modules, the third terminal of the first switching device K1 is electrically connected to the first terminal of the second switching device K2. The second terminal of the second switching device K2 is electrically connected to the battery management system. In the last switching module, the third terminal of the second switching device K2 is electrically connected to the negative terminal of the battery cell and the power converter, respectively. In the remaining switching modules, the third terminal of the second switching device K2 is electrically connected to the negative terminal of the battery cell and the first terminal of the second switching device K2 in the next switching module, respectively.

[0026] Specifically, both the first switching device K1 and the second switching device K2 can be in dual-switching mode or single-pole double-throw mode, such as relays, field-effect transistors, etc.

[0027] In this embodiment, each switching module includes a first switching device K1 and a second switching device K2. When it is necessary to bypass the cells in the battery module, this can be achieved by controlling the second switching device K2 to be connected and the first switching device K1 to be disconnected. For example, when the switching module consists of two back-to-back MOSFETs, the battery management module can output a drive control signal to the two switching switches to change their connection state.

[0028] like Figure 3 The diagram shown is a structural schematic of the third type of energy storage battery pack provided in this embodiment. Please refer to [link / reference]. Figure 3 The battery management system includes a sampling module, an equalization module, a control module, and a communication module. The sampling module is electrically connected to the battery module, the equalization module, and the control module respectively. The communication module is electrically connected to the control module and is used for electrical connection to the control bus. The control module is also electrically connected to the equalization module, the switching module, and the power converter. The equalization module is also connected to the sampling module, or the equalization module is also electrically connected to the battery module.

[0029] Specifically, in this embodiment, the Battery Management System (BMS) can collect signals such as voltage, current, and temperature of each cell through a sampling module, and then achieve energy balancing among the individual battery cells (i.e., the battery pack) and charge / discharge management through an balancing module and a control module. The sampling module can include voltage sampling circuits, current sampling circuits, and temperature sampling circuits. The voltage sampling circuit measures the voltage of each cell and can use a resistor divider circuit, analog-to-digital converter (ADC), etc., for sampling. The current sampling circuit can measure the cell current using a Hall sensor, shunt resistor, or other current sensor. The temperature sampling circuit can use a thermocouple, PT100, NTC, or PTC temperature sensor to monitor the temperature of the individual battery cells. The balancing module mainly achieves energy balancing among the cells, ensuring that the charge level of each cell remains consistent and preventing overcharging, over-discharging, or damage caused by cell imbalance. The balancing module can be an active balancing circuit, a passive balancing circuit, or a combination of several balancing technologies. Passive balancing dissipates excess charge from cells with higher charge levels, typically by releasing the excess charge as heat. Active balancing uses power transfer technology to transfer energy from cells with higher charge levels to cells with lower charge levels. Through balancing control by the battery management system, the power converter in the battery pack can manage the pack without considering imbalances between cells. The communication module can send sampled data to the control module via a communication interface, and also enables communication between the external control bus and the battery pack, ultimately allowing the control module to control the battery modules and power converter.

[0030] Furthermore, the power converter includes a single-stage isolated DC / DC converter or a two-stage isolated DC / DC converter.

[0031] Specifically, the isolated DC / DC converter in this embodiment can be a DAB converter, a CLLC converter, or a combination of a two-stage non-isolated converter and a fixed-gain resonant converter (e.g., a combination of a buck circuit and an LLC resonant converter). Since the battery packs are directly connected to the DC bus through the isolated DC / DC converter, i.e., the battery packs are in parallel, the isolated DC / DC converter only needs to meet the voltage regulation range of a single battery pack. The gain range is relatively small, eliminating the need to design the DC / DC converter as a wide input voltage range converter, greatly simplifying the converter design structure and reducing costs.

[0032] like Figure 4 The diagram shown is a structural schematic of a power converter provided in this embodiment. Please refer to [link / reference]. Figure 4The isolated DC / DC converter is a DAB converter, which includes a first H-bridge circuit, a second H-bridge circuit, and a transformer. The first and second terminals of the first H-bridge circuit are electrically connected to the DC bus, and the third and fourth terminals of the first H-bridge circuit are electrically connected to the transformer. The first and second terminals of the second H-bridge circuit are electrically connected to the transformer, and the third and fourth terminals of the second H-bridge circuit are electrically connected to the battery module.

[0033] Specifically, this embodiment provides an isolated DC-DC converter (Dual Active Bridge) that mainly includes two H-bridge circuits. The first H-bridge circuit converts the input DC power supply into an AC signal, with electrical isolation and voltage conversion provided by a transformer. The second H-bridge circuit then converts the converted AC signal back into a DC signal for transmission to the battery module to charge it. The principle is similar when the battery module discharges, and will not be elaborated here. The H-bridge circuit includes four switching elements, such as field-effect transistors and insulated-gate bipolar transistors, and the switching elements are controlled to turn on and off according to the control module in the battery management system. The control module can be a microcontroller, a single-chip microcomputer, or other logic circuits.

[0034] Further, please see Figure 3 The energy storage battery pack also includes an auxiliary power supply, which is electrically connected to the battery management system, the switching module and the power converter, and is also used for electrical connection to the control bus.

[0035] The energy storage battery pack provided in this embodiment includes multiple battery modules. The cells in each battery module are connected in series via a switching module, which can increase the overall voltage of the battery pack. Then, the series-connected battery modules are connected to the DC bus through a power converter. That is, a single battery pack is directly connected to the DC bus without needing to be connected in series with other battery packs. Therefore, if a battery module malfunctions, it can be disconnected from the battery pack by the switching module without affecting the operation of the remaining battery modules. Since the voltage gain change caused by disconnecting a few malfunctioning battery modules is small, and the battery management system manages their charge and discharge, the power converter does not need an extremely wide input voltage range, simplifying the converter's design structure. Furthermore, the entire battery pack can be disconnected from the system via the power converter, thereby improving the system's capacity utilization and stability.

[0036] This utility model embodiment also provides an energy storage system; please refer to [link / reference]. Figure 5 The diagram shows the structure of an energy storage system, which includes multiple energy storage battery packs, all of which are connected in parallel to a DC bus.

[0037] It should be noted that the various embodiments in this utility model are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0038] It should also be noted that, in the present invention, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in the present invention may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy storage battery pack, characterized by, include: The system includes a power converter, a battery management system, and multiple battery modules connected in series. Each battery module includes an electrically connected switching module and battery cells. The power converter is electrically connected to the switching modules in the first and last battery modules and is used for electrical connection to an external DC bus. The battery management system is electrically connected to the battery modules and the power converter and is used for electrical connection to an external control bus.

2. The energy storage battery pack of claim 1, wherein, The switching module includes a first switching device and a second switching device; The first terminal of the first switching device is electrically connected to the positive terminal of the battery cell, the second terminal of the first switching device is electrically connected to the battery management system, the third terminal of the first switching device in the first switching module is electrically connected to the power converter and the first terminal of the second switching device respectively, and the third terminal of the first switching device in the remaining switching modules is electrically connected to the first terminal of the second switching device. The second terminal of the second switching device is electrically connected to the battery management system. In the last switching module, the third terminal of the second switching device is electrically connected to the negative terminal of the battery cell and the power converter, respectively. In the remaining switching modules, the third terminal of the second switching device is electrically connected to the negative terminal of the battery cell and the first terminal of the second switching device in the next switching module, respectively.

3. The energy storage battery pack of claim 2, wherein, Both the first switching device and the second switching device include any one of the following: a relay and a field-effect transistor.

4. The energy storage battery pack of claim 1, wherein, The battery management system includes a sampling module, an equalization module, a control module, and a communication module; The sampling module is electrically connected to the battery module and the control module respectively; the communication module is electrically connected to the control module and is used to be electrically connected to the control bus; the control module is also electrically connected to the equalization module, the switching module and the power converter; the equalization module is also connected to the sampling module, or the equalization module is also electrically connected to the battery module.

5. The energy storage battery pack of claim 4, wherein, The equalization module includes any one of the following: an active equalization circuit or a passive equalization circuit.

6. The energy storage battery pack of claim 1, wherein, The power converter includes a single-stage isolated DC / DC converter or a two-stage isolated DC / DC converter.

7. The energy storage battery pack of claim 6, wherein, The isolated DC / DC converter includes any of the following: DAB converter, CLLC converter, and Buck-LLC converter.

8. The energy storage battery pack of claim 7, wherein, The isolated DC / DC converter is a DAB converter, which includes a first H-bridge circuit, a second H-bridge circuit, and a transformer. The first and second ends of the first H-bridge circuit are both electrically connected to the DC bus, and the third and fourth ends of the first H-bridge circuit are both electrically connected to the transformer; the first and second ends of the second H-bridge circuit are both electrically connected to the transformer, and the third and fourth ends of the second H-bridge circuit are both electrically connected to the battery module.

9. The energy storage battery pack of claim 1, wherein, It also includes an auxiliary power supply, which is electrically connected to the battery management system, the switching module and the power converter, and is used to be electrically connected to the control bus.

10. An energy storage system, characterized in that, It includes multiple energy storage battery packs as described in any one of claims 1 to 9, wherein each of the multiple energy storage battery packs is connected in parallel with a DC bus.

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