Multi-stage active equalization energy storage method and active equalization energy storage system thereof

Abstract

The invention discloses a multi-stage active equalization energy storage method and an active equalization energy storage system thereof, and the method comprises the following strategies: when the voltage of any cell monomer in a battery module where the cell monomer is located is the highest, the cell monomer discharges to charge the battery module where the cell monomer is located; when the maximum voltage difference value among the plurality of battery modules in the same battery pack is greater than a preset module voltage difference value, the high-voltage battery module discharges to charge the low-voltage battery module; when the voltage of any battery pack at any moment is lower than a set threshold value, the battery pack is in an over-low voltage state, and active synergistic equalization is triggered; when the maximum voltage difference value between the plurality of battery packs is greater than the preset battery pack voltage difference value, triggering hybrid equalization; and when the temperature of the equalization resistor is higher than a preset temperature value, the high-voltage battery pack triggers discharge equalization. According to the invention, the loss of energy in the form of heat in the equalization process is reduced, and the service life and performance of the battery pack are ensured.

Description

Technical Field

[0001] The present invention relates to the field of energy storage safety technology, in particular to a multi-level active balanced energy storage method and an active balanced energy storage system thereof. Background Art

[0002] The balancing strategy is the main means for the energy storage system to maintain the voltage balance of multiple energy storage units. Affected by various factors, the energy storage system will inevitably cause voltage differences between the energy storage units during the charging and discharging process, resulting in inconsistent charging and discharging processes for each battery, which will affect the battery's service life and performance. Common balancing strategies include active balancing and passive balancing. Passive balancing consumes excess energy in the form of heat. This method is not only inefficient, but also has a large energy loss. Active balancing requires frequent charging and discharging switching, which has a greater impact on the battery pack's service life and overall performance. Summary of the invention

[0003] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a multi-level active balancing energy storage method and an active balancing energy storage system thereof, which can reduce the loss of energy in the form of heat during the balancing process and ensure the service life and performance of the battery pack.

[0004] Technical solution: To achieve the above-mentioned purpose, a multi-level active balanced energy storage method and an active balanced energy storage system of the present invention are provided, which realize voltage balance of each battery pack when charging multiple battery packs at the same time by configuring an energy storage cabinet and a battery management module with an active balanced energy storage system;

[0005] Specific strategies include the following:

[0006] S1. When the voltage of any cell in the battery module is the highest, the cell is discharged to charge the battery module;

[0007] S2. When the maximum voltage difference between multiple battery modules in the same battery pack is greater than the preset module voltage difference, the high-voltage battery module discharges to charge the low-voltage battery module;

[0008] S3: When the voltage of any battery pack is lower than the set threshold at any time, it is in an undervoltage state, triggering active efficiency balancing;

[0009] S4. When the maximum voltage difference between multiple battery packs is greater than the preset battery pack voltage difference, hybrid balancing is triggered, including active efficiency-enhancing balancing triggered by low-voltage battery packs and passive efficiency-reducing balancing triggered by high-voltage battery packs;

[0010] S5. When the temperature of the balancing resistor is higher than the preset temperature value, the high-voltage battery pack triggers discharge balancing, and the high-voltage battery pack discharges to charge the low-voltage battery pack;

[0011] S6. When the voltage of any battery pack reaches the protection voltage value, the connection between the battery pack and the power source is cut off.

[0012] Furthermore, in strategy S2, the current average voltage of multiple battery modules in the same battery pack is used as a reference, and the battery modules with voltages higher than the average voltage are high-voltage battery modules, and the battery modules with voltages lower than the average voltage are low-voltage modules.

[0013] Furthermore, the discharge direction of the high voltage battery module is bidirectional.

[0014] Furthermore, in strategy S3, the set threshold is an ideal voltage threshold range generated by the change of normal charging efficiency over time.

[0015] Furthermore, in strategy S4, taking the voltage average value of multiple battery packs being charged in the energy storage cabinet as a reference, a battery pack whose current voltage value is lower than the voltage average value is a low-voltage battery pack; and a battery pack whose current voltage value is higher than the set threshold is a high-voltage battery pack.

[0016] Furthermore, it includes a main control module and a slave control module, the main control module is used to control the voltage balance between the multiple battery packs, and the slave control module is used to control the voltage balance between the battery modules inside each battery pack and the battery cells in each module.

[0017] Furthermore, the main control module includes a main control board, a power supply and a balancing control chain, the balancing control chain includes a plurality of balancing control units, a plurality of the balancing control units correspond one-to-one to a plurality of battery packs, and the power supply circuit of the power supply is electrically connected to the electrodes of the plurality of battery packs through the plurality of the balancing control units; the main control board is electrically connected to the balancing control chain for sending control instructions to each of the balancing control units, the balancing control unit executes the instructions to complete the selection of the conduction relationship between the corresponding battery pack and the power supply circuit, so as to realize switching between strategies SS; the slave control module includes a plurality of battery management modules of the battery packs, and the plurality of the battery management modules are electrically connected to the main control board, for the battery management module to upload voltage information to the main control board, and for the main control board to send instructions to the battery management module.

[0018] Furthermore, the balancing control unit includes a charging circuit, an efficiency-enhancing balancing circuit, a efficiency-reducing balancing circuit, a discharging balancing circuit and a circuit switching module. The circuit switching module is a switch tube matrix, and the electrical signal receiving end of each switch tube therein is electrically connected to the control signal output end of the main control board.

[0019] Furthermore, a plurality of bidirectional balancing modules are provided corresponding to the plurality of battery modules, and the plurality of bidirectional balancing modules include a common charging conduction branch and a corresponding separate discharging conduction branch, and the discharging conduction branch is connected to a plurality of common terminals of the battery cells in the corresponding battery module; the conduction control signal receiving ends of the charging conduction branch and the discharging conduction branch are both electrically connected to the control signal output end of the battery management module of the corresponding battery pack.

[0020] Furthermore, both ends of each of the battery cells are respectively connected to a discharge control module via wires for detecting the voltage at both ends of the corresponding battery cell. The discharge control module is connected to the corresponding battery management module for data exchange and transmission for controlling the on / off state of the wires at both ends. The wires at both ends are turned on to form a discharge circuit. The discharge circuit is inductively connected to the charging circuit of the battery module where the battery cell is located through a transformer, so that when the discharge circuit is turned on to generate a discharge current, the charging circuit induces a charging current.

[0021] Beneficial effects: The multi-level active balanced energy storage method and active balanced energy storage system of the present invention form internal active balance between the battery cell and the battery module, without the intervention of an external power supply. Between battery packs, under the premise of ensuring the balance of each internal battery module, the active and passive balance are switched reasonably to ensure the stable charging efficiency of each battery pack, reduce the number of active discharge balance and passive consumption balance, effectively reduce the loss of energy in the form of heat, and ensure the service life and performance of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a strategy block diagram of the multi-level active balanced energy storage method of the present invention;

[0023] Figure 2 It is a schematic diagram of the overall structure of an embodiment of the active balanced energy storage system of the present invention;

[0024] Figure 3 A schematic diagram of the structure of an embodiment of a balancing control unit of the present invention;

[0025] Figure 4 A schematic diagram of the circuit structure of an embodiment of a bidirectional equalization module of the present invention;

[0026] Figure 5 The figure is a schematic diagram of a partial circuit structure of an embodiment of a discharge circuit of a battery cell of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] As attached Figure 1-5The multi-level active balancing energy storage method and the active balancing energy storage system thereof realize voltage balancing of each battery pack when charging multiple battery packs at the same time by configuring an energy storage cabinet and a battery management module with the active balancing energy storage system;

[0029] Specific strategies include the following:

[0030] S1. When the voltage of any battery cell is the highest in the battery module where it is located, the battery cell discharges to charge the battery module where it is located; that is, when there is a voltage difference between the smallest energy storage units in the battery pack, no external power supply is required to achieve internal balance. Active balance between the battery cells ensures the voltage balance of each battery cell, avoids excessive voltage of a certain battery cell and suppresses the storage capacity of the entire battery module, and maximizes the storage capacity of each battery module.

[0031] S2. When the maximum voltage difference between multiple battery modules in the same battery pack is greater than the preset module voltage difference, the high-voltage battery module discharges to charge the low-voltage battery module; wherein, taking the current average voltage of multiple battery modules in the same battery pack as a reference, the battery module with a voltage higher than the average voltage is a high-voltage battery module, and the battery module with a voltage lower than the average voltage is a low-voltage module. Based on strategy S1, under the premise of ensuring that the charging efficiency of multiple battery cells in each battery module is consistent, when there is a large voltage difference between battery modules, strategy S2 is triggered, and the high-voltage battery module actively discharges to charge the low-voltage battery module, thereby reducing the voltage difference between battery modules. Take the current average voltage of multiple battery modules as a reference to improve the precise control of the discharge process. The voltage average value changes in real time with the total voltage of the battery pack, and can be calculated by collecting the real-time total voltage of the battery pack and the connection relationship between the battery modules inside the battery pack. When the high-voltage battery module is discharged, the voltage will stop discharging after it approaches the dynamic average voltage, and the normal charging state will be restored until all battery modules stop discharging and the internal balance at the module level is completed. And the discharge direction of the high-voltage battery module is bidirectional. It can be discharged from the high-voltage point to both sides, and at the same time, it can be transmitted faster to the nearest low-voltage battery module for charging, thereby improving the balance efficiency. And this process does not require an external power supply to achieve balance, reducing the difficulty of active balance control.

[0032] S3. When the voltage of any battery pack is lower than the set threshold at any time, it is in an over-low voltage state, triggering active efficiency enhancement and balancing, and connecting the power supply to the battery pack with over-low voltage through an independent balancing harness to improve charging efficiency; the set threshold is the ideal voltage threshold range generated by the normal charging efficiency changing over time. When all battery packs are lower than the set threshold, it indicates that the overall charging efficiency is low, and active efficiency enhancement is used to improve the overall charging efficiency. The independent balancing harness uses a wire with a larger conduction amount.

[0033] S4. When the maximum voltage difference between multiple battery packs is greater than the preset battery pack voltage difference, hybrid balancing is triggered, including active efficiency-enhancing balancing triggered by low-voltage battery packs and passive efficiency-reducing balancing triggered by high-voltage battery packs; wherein, the passive efficiency-reducing balancing is achieved by suppressing the charging current through a balancing resistor; taking the voltage average value of multiple battery packs being charged in the energy storage cabinet as a reference, the battery pack whose current voltage value is lower than the voltage average value is a low-voltage battery pack; the battery pack whose current voltage value is higher than the set threshold is a high-voltage battery pack. By suppressing the charging current of the high-voltage battery pack, the low-voltage battery pack is charged with efficiency enhancement to accelerate the reduction of the voltage gap, and only the high-voltage battery pack that exceeds the set threshold is passively balanced. In order to ensure that the final balanced voltage approaches the set threshold, the mutual voltage difference is kept small, while ensuring the overall charging efficiency is normal, and effectively reducing the energy consumption caused by passive balancing.

[0034] S5. When the temperature of the balancing resistor is higher than the preset temperature value, the high-voltage battery pack triggers discharge balancing, and the high-voltage battery pack discharges to charge the low-voltage battery pack; when the energy consumed by passive balancing is too much and the heat generated is too large, active discharge is used to charge the low-voltage battery pack to accelerate the reduction of the voltage difference, while reducing energy loss, maintaining normal charging temperature, and avoiding safety problems. Frequent heavy discharge also affects the service life and performance of the battery, so through the coordination of strategy S4 and strategy S5, passive balancing and active balancing are reasonably triggered to minimize energy loss and extend the service life of the battery pack.

[0035] S6. When the voltage of any battery pack reaches the protection voltage value, the connection between the battery pack and the power source is cut off. Balancing can ensure that the charging efficiency of multiple battery packs is almost consistent, but it cannot be absolutely consistent. When a battery pack is charged first, it will automatically disconnect from the power source and other battery packs to avoid false triggering or discharge again due to active balancing interference, so that balancing only occurs between battery packs that are not fully charged.

[0036] The active balancing energy storage system includes a master control module and a slave control module. The master control module is used to control the voltage balance between the multiple battery packs, and the slave control module is used to control the voltage balance between the battery modules 41 inside each battery pack 4 and the battery cells 411 in each module. The slave control module is composed of a plurality of BMS system modules of the battery packs, and can be connected to the master control module in a daisy chain connection to complete the upload of voltage acquisition data and the issuance of internal balancing instructions of the battery pack. The master control module is arranged in the high-voltage control box of the energy storage cabinet, and the battery pack is correspondingly inserted in the slot of the energy storage cabinet. The battery pack is connected to the power supply through the interface in the slot, and its battery management module is connected to the slave control chain. When the battery pack is pulled out of the energy storage cabinet, the battery pack is separated from the master control module and the slave control chain, and the energy storage cabinet and the remaining battery packs therein can still constitute a complete active balancing energy storage system. The slave control module inside the removed battery pack becomes an independent balancing system, which ensures the voltage balance between the internal battery modules and battery cells during the use of the battery pack, thereby further extending the battery life and performance.

[0037] The main control module includes a main control board 1, a power supply 2 and a balancing control chain 3, the balancing control chain 3 includes a plurality of balancing control units 30, a plurality of the balancing control units 30 correspond one to one with a plurality of battery packs 4, and the power supply circuit 21 of the power supply 2 is electrically connected to the electrodes of the plurality of battery packs 4 through the plurality of balancing control units 30; the main control board 1 is electrically connected to the balancing control chain 3 for sending control instructions to each of the balancing control units 30, and the balancing control unit 30 executes the instructions to complete the selection of the conduction relationship between the corresponding battery pack 4 and the power supply circuit 21, so as to realize the switching between the strategies S3-S6; wherein, the balancing control unit 30 adopts a switch tube matrix to realize the conduction selection of some lines, and the conduction control signal receiving end of each switch tube is electrically connected to the main control board 1.

[0038] The slave control module includes multiple battery management modules 40 of the battery pack 4, and the multiple battery management modules 40 are electrically connected to the main control board 1, so that the battery management modules 40 upload voltage information to the main control board 1, and the main control board 1 sends instructions to the battery management modules 40.

[0039] The balancing control unit 30 includes a charging circuit 31, an efficiency-enhancing balancing circuit 32, a efficiency-reducing balancing circuit 33, a discharging balancing circuit 34 and a circuit switching module 35. The circuit switching module 35 is a switch tube matrix, and the electrical signal receiving end of each switch tube therein is electrically connected to the control signal output end of the main control board 1.

[0040] Multiple bidirectional balancing modules 5 are provided corresponding to the multiple battery modules 41, and the multiple bidirectional balancing modules 5 include a common charging conduction branch 51 and a corresponding discharge conduction branch 52. The discharge conduction branch 52 is connected to multiple common terminals of the battery cells 411 in the corresponding battery module 41; the conduction control signal receiving ends of the charging conduction branch 51 and the discharge conduction branch 52 are electrically connected to the control signal output end of the battery management module 40 of the corresponding battery pack.

[0041] Preferably, each of the discharge conduction branches 52 is inductively connected to the charge conduction branch 51 through a transformer. The charge conduction branch 51 is divided into multiple sections by the coils of multiple transformers. Each section of the charge conduction branch 51 is controlled to be turned on by a separate switch tube to form a charging current, and each discharge conduction branch 52 is also controlled by a separate switch tube to form a reverse discharge current. A bidirectional balancing module 5 is formed by the transformer and the two switch tubes. The two switch tubes are alternately turned on to realize charge and discharge control. Multiple bidirectional balancing modules 5 are connected in communication to coordinate the transmission of control signals. When a certain section of the charging conduction branch 51 is turned on to generate current, a relatively reverse charging current is correspondingly generated in the plurality of the discharge conduction branches 52. When the voltage of a certain battery module is too high, the discharge conduction branch 52 corresponding to the battery module is actively turned on to generate a reverse discharge current, while the remaining discharge conduction branches 52 still contain charging current, thereby allowing the current released by the high-voltage battery module to be incorporated into the charging current of other battery modules to complete the charging of other battery modules. After the voltage returns to normal, the charging current is switched back to continue charging by switching the conductive switch tube.

[0042] Since the discharge conduction branch 52 is connected to the common terminal of multiple cells, multiple cells can be charged evenly at the same time. During the discharge process, multiple cells are discharged at the same time, which avoids the bidirectional balance between battery modules affecting the balance between cells inside the battery module.

[0043] The two ends of each battery cell 411 are respectively connected to the discharge control module 6 through wires, which are used to detect the voltage at the two ends of the corresponding battery cell 411. The discharge control module 6 is connected to the corresponding battery management module 40 for data exchange and transmission, and is used to control the on-off state of the wires at both ends. The wires at both ends are turned on to form a discharge circuit 61. The discharge circuit 61 is inductively connected to the charging circuit 62 of the battery module 41 where the battery cell 411 is located through a transformer, and when the discharge circuit 61 is turned on to generate a discharge current, the charging circuit 62 inductively generates a charging current. When the wires at both ends are not connected to each other, the discharge circuit is in an open circuit state and is only used to detect the voltage at both ends of the battery cell. The discharge control module 6 collects the voltage signal and transmits it to the battery management module 40. After comparing with the voltage of other battery cells, the discharge control module 6 corresponding to the battery cell with the highest voltage sends a balancing start instruction, thereby turning on the corresponding discharge circuit 61, generating a discharge current from the positive electrode to the negative electrode of the battery cell, and inducing a charging current from the negative electrode to the positive electrode of the battery module in the corresponding charging circuit 62 through the transformer, thereby achieving the purpose of discharging the battery cell with the highest voltage in the battery module and charging the entire battery module, thereby ensuring the voltage balance between the battery cells in the battery module.

[0044] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the above principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A multi-level active balanced energy storage method, characterized in that: By configuring the energy storage cabinet and battery management module with active balancing energy storage system, voltage balancing of each battery pack is achieved when multiple battery packs are charged at the same time; Specific strategies include the following: S1. When the voltage of any cell in the battery module is the highest, the cell is discharged to charge the battery module; S2. When the maximum voltage difference between multiple battery modules in the same battery pack is greater than the preset module voltage difference, the high-voltage battery module discharges to charge the low-voltage battery module; S3: When the voltage of any battery pack is lower than the set threshold at any time, it is in an undervoltage state, triggering active efficiency balancing; S4. When the maximum voltage difference between multiple battery packs is greater than the preset battery pack voltage difference, hybrid balancing is triggered, including active efficiency-enhancing balancing triggered by low-voltage battery packs and passive efficiency-reducing balancing triggered by high-voltage battery packs; S5. When the temperature of the balancing resistor is higher than the preset temperature value, the high-voltage battery pack triggers discharge balancing, and the high-voltage battery pack discharges to charge the low-voltage battery pack; S6. When the voltage of any battery pack reaches the protection voltage value, the connection between the battery pack and the power source is cut off.

2. A multi-stage active balanced energy storage method according to claim 1, characterized in that: In strategy S2, the current average voltage of multiple battery modules in the same battery pack is used as a reference. Battery modules with voltages higher than the average voltage are high-voltage battery modules, and battery modules with voltages lower than the average voltage are low-voltage modules.

3. A multi-stage active balanced energy storage method according to claim 2, characterized in that: The discharge direction of the high voltage battery module is bidirectional.

4. A multi-stage active balanced energy storage method according to claim 3, characterized in that: In strategy S3, the set threshold is an ideal voltage threshold range generated by the normal charging efficiency changing with time.

5. A multi-stage active balanced energy storage method according to claim 4, characterized in that: In strategy S4, the average voltage value of multiple battery packs being charged in the energy storage cabinet is used as a reference, and the battery pack whose current voltage value is lower than the average voltage value is a low-voltage battery pack; A battery pack whose current voltage value is higher than the set threshold is a high-voltage battery pack.

6. An active balancing system of a multi-level active balancing energy storage method according to any one of claims 1 to 5, characterized in that: It comprises a main control module and a slave control module, wherein the main control module is used to control the voltage balance between the plurality of battery packs, and the slave control module is used to control the voltage balance between the battery modules (41) inside each battery pack (4) and the battery cells (411) in each module.

7. The active balancing system of the multi-level active balancing energy storage method according to claim 1, characterized in that: The main control module comprises a main control board (1), a power source (2) and a balancing control chain (3), wherein the balancing control chain (3) comprises a plurality of balancing control units (30), wherein the plurality of balancing control units (30) correspond to the plurality of battery packs (4) in a one-to-one manner, and the power supply circuit (21) of the power source (2) is electrically connected to the electrodes of the plurality of battery packs (4) through the plurality of balancing control units (30); the main control board (1) is electrically connected to the balancing control chain (3) for sending signals to each of the balancing control units (30). The control instruction is sent, and the balancing control unit (30) executes the instruction to complete the selection of the conduction relationship between the corresponding battery pack (4) and the power supply circuit (21), so as to realize the switching between strategies S3-S6; the slave control module includes a plurality of battery management modules (40) of the battery pack (4), and the plurality of battery management modules (40) are electrically connected to the main control board (1), so that the battery management modules (40) upload voltage information to the main control board (1), and the main control board (1) sends instructions to the battery management modules (40).

8. The active balancing system of the multi-level active balancing energy storage method according to claim 7, characterized in that: The balancing control unit (30) comprises a charging circuit (31), an efficiency-enhancing balancing circuit (32), an efficiency-reducing balancing circuit (33), a discharging balancing circuit (34), and a circuit switching module (35); the circuit switching module (35) is a switch tube matrix, wherein the electrical signal receiving end of each switch tube is electrically connected to the control signal output end of the main control board (1).

9. The active balancing system of the multi-level active balancing energy storage method according to claim 8, characterized in that: A plurality of bidirectional balancing modules (5) are provided corresponding to the plurality of battery modules (41), and the plurality of bidirectional balancing modules (5) include a common charging conduction branch (51) and a corresponding separate discharging conduction branch (52), wherein the discharging conduction branch (52) is connected to a plurality of common terminals of the battery cells (411) in the corresponding battery module (41); and the conduction control signal receiving terminals of the charging conduction branch (51) and the discharging conduction branch (52) are both electrically connected to the control signal output terminal of the battery management module (40) of the corresponding battery pack.

10. The active balancing system of the multi-level active balancing energy storage method according to claim 9, characterized in that: The two ends of each battery cell (411) are respectively connected to a discharge control module (6) via a wire, and are used to detect the voltage at the two ends of the corresponding battery cell (411). The discharge control module (6) is connected to the corresponding battery management module (40) for data exchange transmission, and is used to control the on-off state of the wires at the two ends. The wires at the two ends are connected to form a discharge circuit (61). The discharge circuit (61) is inductively connected to a charging circuit (62) of a battery module (41) where the battery cell (411) is located via a transformer, and is used for the charging circuit (62) to induce a charging current when the discharge circuit (61) is turned on to generate a discharge current.

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