An energy storage system and a method for switching between series and parallel connections of sodium-ion batteries.

Abstract

The present invention discloses an energy storage system and a sodium ion battery series-parallel switching method, and relates to the technical field of electrochemical battery manufacturing. An energy storage system of the present invention includes a battery module, a high-voltage box, an energy storage converter PCS, a switch group K1, a switch group K2 and a control program, wherein the battery module includes a plurality of battery cells, and a sodium ion battery series-parallel switching method applied to the energy storage system. The present invention can replace a DC / DC device, increase the internal space utilization of the energy storage system from a structural perspective, increase the system efficiency (about 1-2%) from the perspective of electric energy conversion efficiency, and reduce the cost of the DC / DC converter from a cost perspective. This method can also make sodium ion batteries more compatible with electronic components.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical battery manufacturing, in particular to an energy storage system and a sodium ion battery series-parallel switching method. Background Art

[0002] In recent years, with the rapid development of electric vehicles and large-scale energy storage, the market demand for lithium-ion batteries has been increasing. However, the global reserves of lithium resources are limited and cannot continue to meet the future needs of electric vehicles and large-scale energy storage. The structure and working principle of sodium-ion batteries are similar to those of lithium-ion batteries, and they have the advantages of wide resources, low raw material costs, and production lines compatible with lithium-ion batteries. They can be used as an effective supplement to lithium-ion batteries.

[0003] The voltage range of sodium-ion batteries is much wider than that of other types of batteries, ranging from 1.5V to 4V. Therefore, they are not compatible with existing electronic components. In order to meet the full capacity of the battery, the current solution is to configure a DC / DC device between the battery pack and the energy storage converter (PCS) to meet the adaptation with the energy storage converter (PCS).

[0004] However, the DC / DC device not only takes up too much space inside the energy storage system, making the internal space utilization of the energy storage system too low, but also reduces the energy conversion efficiency of the battery module due to the resistance of the internal components of the DC / DC device, switching losses and energy losses of magnetic components (such as inductors and transformers). Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the problem that in the prior art a DC / DC device needs to be configured between the battery pack and the energy storage converter (PCS) to meet the adaptation requirement with the energy storage converter (PCS), and the problem that the DC / DC device will reduce the internal space utilization of the energy storage system and the energy conversion efficiency of the battery module, the present invention is proposed.

[0007] Therefore, the technical problem to be solved by the present invention is to propose an energy storage system and a sodium ion battery series-parallel switching method to replace the DC / DC device.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: an energy storage system, comprising a battery module, a high-voltage box, an energy storage converter PCS, a switch group K1, a switch group K2 and a control program, wherein the battery module comprises a plurality of battery cells.

[0009] In order to solve the above technical problems, the present invention also provides the following technical solutions: a sodium ion battery series-parallel switching method, applied to the energy storage system as described above, comprising the following steps:

[0010] The energy storage system is powered on and enters the preparation phase, and the control program determines that the energy storage system is in a charging state;

[0011] Before charging starts, when the control program detects that the cell voltage is ≥ V1, < V2, or the total voltage range of the battery module is in the range of (2×M) V1 to (2×M) V2, the control program sends a charging prohibition instruction to the energy storage converter PCS, and triggers the switch group K1 to open and the switch group K2 to close;

[0012] After the energy storage system is in (3×N) parallel and (2×M) series, the control program sends charging power to the energy storage converter PCS;

[0013] The energy storage system continues to enter the charging stage until the system manually or automatically ends the charging process.

[0014] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, wherein: the control program determines that the energy storage system is in a charging state;

[0015] Before charging starts, when the control program detects that the cell voltage is ≥ V0, < V1, or the total voltage of the battery module is in the range of (3×M) V0 to (3×M) V1, the control program sends a charging prohibition instruction to the energy storage converter PCS, and triggers the switch group K2 to open and the switch group K1 to close;

[0016] After the energy storage system is in (2×N) parallel and (3×M) series, the control program sends charging power to the energy storage converter PCS, and the system enters the charging stage.

[0017] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, wherein: the control program determines that the energy storage system is in a charging state;

[0018] When the control program detects that the total voltage of the energy storage system reaches (2×M) V1, the control program sends charging power to the energy storage converter PCS;

[0019] The energy storage system continues to enter the charging stage until the system manually or automatically ends the charging process.

[0020] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, wherein: the energy storage system is powered on and enters the preparation stage, and the control program determines that the energy storage system is in a discharge state;

[0021] Before discharge begins, when the control program detects that the cell voltage is ≥ V0, < V1, or the total voltage of the battery module is in the range of (3×M) V0 to (3×M) V1, the control program sends a discharge prohibition instruction to the energy storage converter PCS, and triggers the switch group K2 to open and the switch group K1 to close;

[0022] After the energy storage system is in (2×N) parallel and (3×M) series, the control program sends the discharge power to the energy storage converter PCS;

[0023] The energy storage system enters the discharge phase until the system manually or automatically ends the discharge process.

[0024] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, wherein: the control program determines that the energy storage system is in a discharging state;

[0025] Before discharge begins, when the control program detects that the cell voltage is ≥ V1, < V2 or the total voltage of the battery module is in the range of (2×M) V1 to (2×M) V2, the energy storage converter PCS issues a discharge prohibition instruction and triggers the switch group K1 to open and the switch group K2 to close;

[0026] After the energy storage system is in (3×N) parallel and (2×M) series, the control program sends the discharge power to the energy storage converter PCS;

[0027] The energy storage system enters the discharging stage.

[0028] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, when the control program detects that the total voltage of the battery module reaches (2×M) V1, the control program sends the discharge power to the energy storage converter PCS;

[0029] The energy storage system enters the discharge phase until the system manually or automatically ends the discharge process.

[0030] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, when the switch group K1 is disconnected and the switch group K2 is closed, the energy storage system is in (3×N) parallel and (2×M) series, N≥1, M≥1;

[0031] When switch K2 is open and switch K1 is closed, the energy storage system is in (2×N) parallel and (3×M) series, where N≥1 and M≥1.

[0032] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, when (3×M)V1>(2×M)V2, the total voltage range of the energy storage system is (3×M)V0~(3×M)V1;

[0033] When (3×M)V1<(2×M)V2, the total voltage range of the system is (3×M)V0~(2×M)V2.

[0034] As a preferred solution of the sodium ion battery series-parallel switching method of the present invention, the control program selects a battery management system BMS or an energy management system EMS.

[0035] Beneficial effects of the present invention: The present invention can replace the DC / DC device, increase the internal space utilization of the energy storage system from the structural point of view, increase the system efficiency (about 1~2%) from the perspective of power conversion efficiency, reduce the cost of the DC / DC converter from the perspective of cost, and can also make the sodium ion battery more compatible with electronic components through this method. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0037] Figure 1 It is the (2×N) parallel (3×M) series battery series energy storage system of the present invention;

[0038] Figure 2 It is the (3×N) parallel (2×M) series battery series energy storage system of the present invention;

[0039] Figure 3 is a series wiring diagram of a sodium ion battery of the present invention;

[0040] Figure 4 is a series equivalent circuit diagram of sodium ion batteries of the present invention;

[0041] Figure 5 This is a parallel wiring diagram of sodium ion batteries of the present invention;

[0042] Figure 6 is a parallel equivalent circuit diagram of sodium ion batteries of the present invention;

[0043] Figure 7 It is the operation logic block diagram of the present invention. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0045] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0047] Example 1

[0048] Reference Figure 3-Figure 6 , which is the first embodiment of the present invention, and this embodiment provides an energy storage system, such as Figure 1 or Figure 2 As shown, the energy storage system includes battery modules (or battery clusters) C1-C6, a high-voltage box, an energy storage converter PCS, a switch group K1, a switch group K2 and a control program, and the battery module includes a plurality of battery cells.

[0049] The switch group K1 includes a switch K1-1, a switch K1-2, and a switch K1-3, and the switch group K2 includes a switch K2-1, a switch K2-2, a switch K2-3, and a switch K2-4.

[0050] The battery module / battery cluster C1-C6 may be composed of 2 or more battery cells, 2 or more modules, or two or more battery clusters.

[0051] The module is characterized by being a unit composed of two or more battery cells connected in series or parallel.

[0052] The battery cluster is characterized by a unit composed of two or more modules connected in series or parallel.

[0053] The control program can be a battery management system BMS or an energy management system EMS.

[0054] like Figure 3 As shown, when the batteries are connected in series, the specific circuit connection method is: the positive electrode of battery C4 is connected to the negative electrode of battery C2 and the negative electrode of battery C1, the positive electrode of battery C3 is connected to the negative electrode of battery C1 and the negative electrode of battery C2, the positive electrode of battery C1 is connected to the positive electrode of battery C2, the negative electrode of battery C1 is connected to the negative electrode of battery C2, the positive electrode of battery C2 is connected to the negative electrode of battery C6 through switch K1-1, the positive electrode of battery C2 is connected to the negative electrode of battery C5 through switch K1-2, and the positive electrode of battery C5 is connected to the positive electrode of battery C6 through switch K1-3.

[0055] The negative electrodes of battery C4 and battery C3 are connected to the external device or system through cables, and the positive electrodes of battery C5 and battery C6 are connected to the external device or system through cables. The series equivalent circuit diagram under this wiring state is as follows Figure 4 shown.

[0056] like Figure 5 As shown, when the batteries are connected in parallel, the specific circuit connection method is: the positive electrode of battery C4 is connected to the negative electrode of battery C2 and the negative electrode of battery C1, the positive electrode of battery C3 is connected to the negative electrode of battery C1 and the negative electrode of battery C2, the positive electrode of battery C1 is connected to the positive electrode of battery C2, the negative electrode of battery C1 is connected to the negative electrode of battery C2, the positive electrode of battery C2 is connected to the positive electrode of battery C6 through switch K2-4, the negative electrode of battery C4 is connected to the negative electrode of battery C5 through switch K2-1, the negative electrode of battery C2 and the positive electrode of battery C4 are connected to the negative electrode of battery C6 through switch K2-2, and the negative electrode of battery C6 is connected to the positive electrode of battery C5 through switch K2-3. The parallel equivalent circuit diagram under this connection state is shown in Figure 6 shown.

[0057] The negative electrode of battery C6 and the positive electrode of battery C2 connect the battery pack to an external device or system through a cable, and the negative electrodes of battery C3 and battery C4 connect the battery pack to an external device or system through a cable.

[0058] The high-voltage box is connected to the battery module, the input and output cable interfaces of the energy storage converter PCS are connected to the high-voltage box, and the control program collects the voltage data of each cell in the battery module / battery cluster C1-C6, and determines the total voltage range of the energy storage system.

[0059] Example 2

[0060] Reference Figures 1 to 6 , which is the second embodiment of the present invention, and is different from the previous embodiment in that: this embodiment provides a sodium ion battery series-parallel switching method, which is applied to the above-mentioned energy storage system. The switching method is characterized in that: when the energy storage system is charging and discharging, the control program collects the voltage data of each battery cell in the battery module / battery cluster C1-C6 and determines the total voltage range of the energy storage system.

[0061] like Figure 2 As shown, when switch K1 is open and K2 is closed, the energy storage system is in (3×N) parallel and (2×M) series, and N≥1 and M≥1 must be satisfied.

[0062] like Figure 1 As shown, when switch K2 is open and K1 is closed, the energy storage system is in (2×N) parallel and (3×M) series, and N≥1 and M≥1 must be satisfied.

[0063] The switch groups K1 and K2 can be made of contactor switches, relay switches, two-position switches, thyristor switches and other similar electrical components.

[0064] Example 3

[0065] Reference Figure 1-7 , which is the third embodiment of the present invention, and which is different from the first two embodiments in that: this embodiment also includes the specific implementation steps of the sodium ion battery series-parallel switching method:

[0066] like Figure 7 As shown, during the charging process:

[0067] Before charging begins, if the energy storage system control unit detects that the battery cell voltage is ≥V0, <V1 or the total voltage of the battery system is in the range of (3×M)V0~(3×M)V1, the control program sends a charging prohibition instruction to the energy storage inverter PCS, and triggers the switch K2 to open and K1 to close, so that the system is in (2×N) parallel and (3×M) series. After that, the control program sends the charging power to the energy storage inverter PCS, and the system enters the charging stage.

[0068] When the control program detects that the total system voltage reaches (2×M)V1, the control program sends a charging prohibition instruction to the energy storage inverter PCS, and triggers the switch K1 to open and K2 to close, so that the system is in (3×N) parallel and (2×M) series. After that, the control program sends the charging power to the energy storage inverter PCS, and the system continues to enter the charging stage until the system manually or automatically ends the charging process.

[0069] Before charging begins, if the energy storage system control unit detects that the cell voltage is ≥V1, <V2 or the total voltage of the battery system is in the range of (2×M)V1~(2×M)V2, the control program sends a charging prohibition instruction to the energy storage inverter PCS, and triggers switch K1 to open and K2 to close, so that the system is in (3×N) parallel and (2×M) series. After that, the control program sends charging power to the energy storage inverter PCS, and the system enters the charging stage until the system manually or automatically ends the charging process.

[0070] During discharge:

[0071] Before discharge begins, if the energy storage system control unit detects that the cell voltage is ≥V1, <V2 or the total voltage of the battery system is in the range of (2×M)V1~(2×M)V2, the control program sends a discharge prohibition instruction to the energy storage converter PCS, and triggers the switch K1 to open and K2 to close, so that the system is in (3×N) parallel and (2×M) series. After that, the control program sends the discharge power to the energy storage converter PCS, and the system enters the discharge stage.

[0072] When the control program detects that the total system voltage reaches (2×M)V1, the control program sends a discharge prohibition instruction to the energy storage inverter PCS, and triggers the switch K2 to open and K1 to close, so that the system is in (2×N) parallel and (3×M) series. After that, the control program sends the discharge power to the energy storage inverter PCS, and the system continues to enter the discharge stage until the system manually or automatically ends the discharge process.

[0073] Before discharge begins, if the energy storage system control unit detects that the cell voltage is ≥V0, <V1 or the total voltage of the battery system is in the range of (3×M)V0~(3×M)V1, the control program sends a discharge prohibition instruction to the energy storage inverter PCS, and triggers the switch K2 to open and K1 to close, so that the system is in (2×N) parallel and (3×M) series. After that, the control program sends the discharge power to the energy storage inverter PCS, and the system enters the discharge stage until the system manually or automatically ends the discharge process.

[0074] The system can narrow the total voltage range of the system by switching between series and parallel during the charging and discharging process.

[0075] When (3×M)V1>(2×M)V2, the total voltage range of the energy storage system is: (3×M)V0~(3×M)V1.

[0076] When (3×M)V1<(2×M)V2, the total voltage range of the energy storage system is: (3×M)V0~(2×M)V2.

[0077] The energy storage system can narrow the total voltage range of the system by switching between series and parallel during the charging and discharging process. When (3×M)V1>(2×M)V2, the total voltage range of the system is: (3×M)V0~(3×M)V1. When (3×M)V1<(2×M)V2, the total voltage range of the system is: (3×M)V0~(2×M)V2.

[0078] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention).

[0079] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0080] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An energy storage system, characterized in that: include, A battery module, a high-voltage box, an energy storage converter PCS, a switch group K1, a switch group K2 and a control program, wherein the battery module includes a plurality of battery cells; The switch group K1 includes switch K1-1, switch K1-2 and switch K1-3, and the switch group K2 includes switch K2-1, switch K2-2, switch K2-3 and switch K2-4; the battery module includes battery C1, battery C2, battery C3, battery C4, battery C5 and battery C6; The battery module connection state includes a series connection state or a parallel connection state; When the battery modules are connected in series, the positive electrode of battery C4 is connected to the negative electrode of battery C2 and the negative electrode of battery C1, the positive electrode of battery C3 is connected to the negative electrode of battery C1 and the negative electrode of battery C2, the positive electrode of battery C1 is connected to the positive electrode of battery C2, the negative electrode of battery C1 is connected to the negative electrode of battery C2, the positive electrode of battery C2 is connected to the negative electrode of battery C6 through switch K1-1, the positive electrode of battery C2 is connected to the negative electrode of battery C5 through switch K1-2, and the positive electrode of battery C5 is connected to the positive electrode of battery C6 through switch K1-3; the negative electrodes of battery C4 and battery C3 connect the battery pack to an external device or system through a cable, and the positive electrodes of battery C5 and battery C6 connect the battery pack to an external device or system through a cable; When the battery modules are connected in parallel, the positive electrode of battery C4 is connected to the negative electrode of battery C2 and the negative electrode of battery C1, the positive electrode of battery C3 is connected to the negative electrode of battery C1 and the negative electrode of battery C2, the positive electrode of battery C1 is connected to the positive electrode of battery C2, the negative electrode of battery C1 is connected to the negative electrode of battery C2, the positive electrode of battery C2 is connected to the positive electrode of battery C6 through switch K2-4, the negative electrode of battery C4 is connected to the negative electrode of battery C5 through switch K2-1, the negative electrode of battery C2 and the positive electrode of battery C4 are connected to the negative electrode of battery C6 through switch K2-2, and the negative electrode of battery C6 is connected to the positive electrode of battery C5 through switch K2-3; the negative electrode of battery C6 and the positive electrode of battery C2 are connected to the external device or system through a cable, and the negative electrodes of battery C3 and battery C4 are connected to the external device or system through a cable; The high-voltage box is connected to the battery module, and the input and output cable interfaces of the energy storage converter PCS are connected to the high-voltage box. The control program collects voltage data of each battery cell in the battery module / battery cluster C1-C6 and determines the total voltage range of the energy storage system.

2. A sodium ion battery series-parallel switching method, characterized in that: The energy storage system as claimed in claim 1 comprises the following steps: The energy storage system is powered on and enters the preparation phase, and the control program determines that the energy storage system is in a charging state; Before charging starts, when the control program detects that the cell voltage is ≥ V1, < V2, or the total voltage range of the battery module is in the range of (2×M) V1 to (2×M) V2, the control program sends a charging prohibition instruction to the energy storage converter PCS, and triggers the switch group K1 to open and the switch group K2 to close; After the energy storage system is in (3×N) parallel and (2×M) series, the control program sends charging power to the energy storage converter PCS; The energy storage system continues to enter the charging stage until the system manually or automatically ends the charging process.

3. The sodium ion battery series-parallel switching method according to claim 2, characterized in that: The control program determines that the energy storage system is in a charging state; Before charging starts, when the control program detects that the cell voltage is ≥ V0, < V1, or the total voltage of the battery module is in the range of (3×M) V0 to (3×M) V1, the control program sends a charging prohibition instruction to the energy storage converter PCS, and triggers the switch group K2 to open and the switch group K1 to close; After the energy storage system is in (2×N) parallel and (3×M) series, the control program sends charging power to the energy storage converter PCS, and the system enters the charging stage.

4. The sodium ion battery series-parallel switching method according to claim 3, characterized in that: The control program determines that the energy storage system is in a charging state; When the control program detects that the total voltage of the energy storage system reaches (2×M) V1, the control program sends charging power to the energy storage converter PCS; The energy storage system continues to enter the charging stage until the system manually or automatically ends the charging process.

5. The sodium ion battery series-parallel switching method according to claim 4, characterized in that: The energy storage system is powered on and enters a preparation phase, and the control program determines that the energy storage system is in a discharging state; Before discharge begins, when the control program detects that the cell voltage is ≥ V0, < V1, or the total voltage of the battery module is in the range of (3×M) V0 to (3×M) V1, the control program sends a discharge prohibition instruction to the energy storage converter PCS, and triggers the switch group K2 to open and the switch group K1 to close; After the energy storage system is in (2×N) parallel and (3×M) series, the control program sends the discharge power to the energy storage converter PCS; The energy storage system enters the discharge phase until the system manually or automatically ends the discharge process.

6. The sodium ion battery series-parallel switching method according to claim 5, characterized in that: The control program determines that the energy storage system is in a discharging state; Before discharge begins, when the control program detects that the cell voltage is ≥ V1, < V2 or the total voltage of the battery module is in the range of (2×M) V1 to (2×M) V2, the energy storage converter PCS issues a discharge prohibition instruction and triggers the switch group K1 to open and the switch group K2 to close; After the energy storage system is in (3×N) parallel and (2×M) series, the control program sends the discharge power to the energy storage converter PCS; The energy storage system enters the discharging stage.

7. The sodium ion battery series-parallel switching method according to claim 6, characterized in that: When the control program detects that the total voltage of the battery module reaches (2×M) V1, the control program sends the discharge power to the energy storage converter PCS; The energy storage system enters the discharge phase until the system manually or automatically ends the discharge process.

8. The sodium ion battery series-parallel switching method according to claim 7, characterized in that: When the switch group K1 is disconnected and the switch group K2 is closed, the energy storage system is in (3×N) parallel and (2×M) series, N≥1, M≥1; When switch K2 is open and switch K1 is closed, the energy storage system is in (2×N) parallel and (3×M) series, where N≥1 and M≥1.

9. The sodium ion battery series-parallel switching method according to claim 8, characterized in that: When (3×M)V1>(2×M)V2, the total voltage range of the energy storage system is (3×M)V0~(3×M)V1; When (3×M)V1<(2×M)V2, the total voltage range of the system is (3×M)V0~(2×M)V2.

10. The sodium ion battery series-parallel switching method according to claim 9, characterized in that: The control program uses a battery management system BMS or an energy management system EMS.

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