A battery system and control method for a residential photovoltaic energy storage device.

Abstract

This invention discloses a battery system and control method for a residential photovoltaic energy storage device. The battery system includes multiple battery packs connected in series or parallel and a high-voltage control box with a BMU module. The BMU module issues a bypass command to a battery pack when it detects that the capacity of a particular battery pack is low. The battery system also includes multiple bypass devices, one of which is connected in parallel to each battery pack. Each battery pack includes a first power transmission positive terminal, a first power transmission negative terminal, a CMU unit, and a first control switch. Each bypass device includes a bypass control board, a first branch, and a second branch. The first branch includes a second control switch and a freewheeling diode connected in series, and the second branch includes a third control switch and a fuse connected in series. The battery system of this invention bypasses the battery pack with lower capacity through the bypass devices without affecting the discharge of other battery packs, thus achieving battery pack balance.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic inverter technology, specifically relating to a battery system and control method for a residential photovoltaic energy storage device. Background Technology

[0002] To meet the high voltage and large capacity requirements of residential photovoltaic energy storage systems, individual cells are often connected in series and parallel to form battery packs, which are then further connected in series or parallel for use. However, during the charging and discharging process of the battery system, the aging degree, state of charge, and health status of each battery pack are inconsistent. As the battery usage time increases, the capacity between battery packs is prone to inconsistency, ultimately shortening the lifespan of the battery pack and even the entire battery system, and even causing safety hazards such as battery deformation and explosion. One solution in the energy storage field is to add an additional equalizer between the packs for balancing. Typically, this equalizer requires high-voltage, high-current power conversion devices, which are expensive. Furthermore, the bypass control process of the battery system requires changing or pausing the existing operating state before bypassing, which is inconvenient and prone to short circuits or open circuits, resulting in low safety. Summary of the Invention

[0003] To address the aforementioned technical problems, the purpose of this invention is to provide an improved battery system and control method for residential photovoltaic energy storage devices.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A battery system for a residential photovoltaic energy storage device includes multiple battery packs connected in series or in parallel and a high-voltage control box with a BMU module. The BMU module is used to issue a bypass command to a battery pack when it detects that the capacity of a certain battery pack is low. The battery system also includes multiple bypass devices, with one bypass device connected in parallel to each battery pack.

[0006] Each of the battery packs includes:

[0007] The battery pack is connected to other battery packs via the first power transmission positive terminal and the first power transmission negative terminal.

[0008] The CMU unit is used to receive bypass instructions sent by the BMU module;

[0009] A first control switch is connected between the first power transmission positive terminal and the first power transmission negative terminal. The first control switch is electrically connected to the CMU unit and can disconnect the first power transmission positive terminal and the first power transmission negative terminal in response to the bypass command.

[0010] Each of the bypass devices includes:

[0011] A bypass control board, which is used to communicate with the CMU unit of the corresponding battery pack;

[0012] The first branch is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack. The first branch includes a second control switch and a freewheeling diode connected in series. The second control switch is electrically connected to the bypass control board.

[0013] The second branch is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack. The second branch includes a third control switch and a fuse connected in series. The third control switch is electrically connected to the bypass control board.

[0014] Preferably, the second control switch is provided with a second contact assembly, and the third control switch is provided with a third contact assembly;

[0015] The second contact assembly includes:

[0016] The second drive contact is used to receive signals from the bypass control board and drive the opening and closing of the second control switch;

[0017] The second feedback contact is used to provide feedback to the bypass control board on the opening and closing status of the second control switch;

[0018] The third contact component includes:

[0019] The third drive contact is used to receive signals from the bypass control board and drive the opening and closing of the third control switch;

[0020] The third feedback contact is used to provide feedback to the bypass control board on the opening and closing status of the third control switch.

[0021] Preferably, each of the battery packs has a first signal output terminal electrically connected to the CMU unit, and each of the bypass devices has a second signal input terminal electrically connected to the bypass controller. The first signal output terminal and the second signal input terminal are electrically connected. The CMU unit is configured to control the level of the first signal output terminal to rise after receiving the bypass command sent by the BMU module, and the bypass controller is configured to control the second control switch to close after the level of the second signal input terminal rises.

[0022] Furthermore, each of the battery packs has a first signal input terminal electrically connected to the CMU unit, and each of the bypass devices has a second signal output terminal electrically connected to the bypass controller, the second signal output terminal being electrically connected to the first signal input terminal; the bypass controller is configured to control the level of the second signal output terminal to rise after the second control switch is closed, and the CMU unit is configured to control the first control switch to open after the level of the first signal input terminal rises; the bypass controller is also configured to control the third control switch to close when it detects that the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is less than or equal to a target voltage value.

[0023] Furthermore, the CMU unit is configured to pull the level of the first signal output terminal low after receiving the parallel connection command from the BMU module; the bypass control board is configured to control the third control switch to open after the level of the second signal input terminal decreases, and to pull the level of the second signal output terminal low after the third switch is opened; the CMU unit is configured to control the first control switch to close after the level of the first signal input terminal decreases; the bypass controller is further configured to control the second control switch to open when it detects that the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is greater than the target voltage value.

[0024] Preferably, the high-voltage control box includes a second power transmission positive terminal and a second power transmission negative terminal for receiving power released from the battery pack. The high-voltage control box is connected to the downstream photovoltaic inverter through the second power transmission positive terminal and the second power transmission negative terminal. Multiple battery packs are connected in series, and the first power transmission negative terminal of the battery pack is electrically connected to the first power transmission positive terminal of the next battery pack.

[0025] Preferably, the high-voltage control box further includes a resonant circuit, which is electrically connected to the first power transmission positive terminal, the first power transmission negative terminal, the second power transmission positive terminal, and the second power transmission negative terminal.

[0026] Preferably, each of the battery packs further includes multiple daisy-chain ports, through which the BMU module sends the bypass command to the CMU unit.

[0027] Preferably, the freewheeling diode is a fast recovery diode, and the maximum rectified current of the freewheeling diode is 60A, and the maximum reverse working voltage is 1200V.

[0028] A control method for a battery system in a residential photovoltaic energy storage device, wherein the battery system is as described above, and the battery system includes a main circuit mode and a bypass mode.

[0029] When the battery system switches from the main circuit mode to the bypass mode, the control method includes:

[0030] S1. The high-voltage control box detects the capacity of the multiple battery packs through the BMU module and determines whether the capacity of each battery pack is lower than a set value. If the BMU module detects that the capacity of a certain battery pack is lower than the set value, it jumps to step S2. Otherwise, it continues to detect.

[0031] S2. The BMU module sends the bypass command to the CMU unit through the daisy-chain port of the corresponding battery pack;

[0032] S3. After receiving the bypass command, the CMU unit controls the level of the first signal output terminal to increase, thereby controlling the bypass device to enter the working state.

[0033] S4. The bypass control board controls the second control switch to close and controls the level of the second signal output terminal to rise, so that the CMU unit receives the closing signal of the second control switch;

[0034] S5. After receiving the closing signal of the second control switch, the CMU unit controls the first control switch to open and reduces the voltage value between the corresponding first power transmission positive terminal and the first power transmission negative terminal to less than or equal to the target voltage value.

[0035] S6. The bypass control board detects whether the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is less than or equal to the target voltage value. If yes, it jumps to step S7; otherwise, it continues to detect.

[0036] S7. Control the third control switch to close;

[0037] When the battery system switches from the bypass mode to the main circuit mode, the control method includes:

[0038] S8. The high-voltage control box detects the capacity of the bypass battery pack through the BMU module and determines whether the capacity of the bypass battery pack is consistent with the capacity of the other battery packs. If yes, it jumps to step S9; otherwise, it continues to detect.

[0039] S9. The BMU module sends a parallel connection command to the CMU unit through the daisy-chain port of the corresponding battery pack;

[0040] S10. After receiving the parallel connection command, the CMU unit controls the level of the first signal output terminal to decrease, thereby controlling the bypass device to enter the preparation to exit state.

[0041] S11. The bypass control board controls the third control switch to open and controls the level of the second signal output terminal to decrease, so that the CMU unit receives the closing signal of the third control switch.

[0042] S12. After receiving the closing signal of the third control switch, the CMU unit controls the first control switch to close.

[0043] S13. The bypass control board detects whether the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is greater than the target voltage value. If yes, it jumps to step S14; otherwise, it continues to detect.

[0044] S14. Control the second control switch to disconnect.

[0045] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0046] The battery system of the residential photovoltaic energy storage device in this invention connects a bypass device in parallel to each battery pack. When the BMU module detects that the capacity of a certain battery pack is low, it issues a bypass command to that battery pack. The bypass device then bypasses the battery pack without affecting the discharge of other battery packs, achieving balance among the battery packs. This battery system maximizes the utilization of all battery capacity through a reasonable algorithm, increasing the overall utilization rate and lifespan of the battery system. The system uses high-voltage diodes as freewheeling devices, allowing battery packs to be bypassed without changing the operating state, and no grid disconnection permission is required during battery pack discharge. The system has a simple structure, high reliability, operates solely through hardware circuitry, and has low cost. Attached Figure Description

[0047] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of the connection of the battery system of the residential photovoltaic energy storage device in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the internal connections of the high-voltage control box in an embodiment of the present invention;

[0050] Figure 3 This is a block diagram illustrating the internal workings of the bypass control board in an embodiment of the present invention.

[0051] Figure 4 This is a flowchart of the control method for switching the battery system from main circuit mode to bypass mode in an embodiment of the present invention;

[0052] Figure 5 This is a flowchart of the control method for switching the battery system from bypass mode to main circuit mode in an embodiment of the present invention;

[0053] The components include: 1. Battery pack; 11. First power transmission positive terminal; 12. First power transmission negative terminal; 13. CMU unit; 14. First control switch; 15. First signal input terminal; 16. First signal output terminal; 17. Daisy-chain connector; 2. Bypass device; 21. Bypass control board; 22. First branch; 23. Second control switch; 231. Second contact assembly; 2311. Second drive contact; 2312. Second feedback contact; 24. Freewheeling diode; 25. Second branch; 26. Third control switch; 261. Third contact assembly; 2611. Third drive contact; 2612. Third feedback contact; 27. Fuse; 28. Second signal input terminal; 29. ​​Second signal output terminal; 3. High voltage control box; 31. BMU module; 32. Second power transmission positive terminal; 33. Second power transmission negative terminal; 34. Resonant circuit. Detailed Implementation

[0054] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these embodiments is for the purpose of aiding understanding the present invention, but does not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] like Figures 1 to 3 As shown, the battery system of the residential photovoltaic energy storage device in this embodiment includes multiple battery packs 1 (i.e., pack1, pack2...packn) connected in series or parallel, a bypass device 2, and a high-voltage control box 3. Each battery pack 1 is connected in parallel with a bypass device 2. The high-voltage control box 3 has a BMU module (battery management unit) 31, which is used to issue a bypass command to a battery pack 1 when it detects that the capacity of a certain battery pack 1 is low. The battery pack 1 is used to store the DC power generated by the photovoltaic panel, and after receiving the discharge command, it supplies the stored electrical energy to the photovoltaic inverter through the high-voltage control box 3, converts it into AC power, and then feeds it back to the grid or AC load.

[0056] Specifically, each battery pack 1 includes a CMU (communication management unit) 13, a first power transmission positive terminal 11 electrically connected to the CMU 13, a second power transmission negative terminal 12 electrically connected to the CMU 13, a first control switch 14, a first signal input terminal 15, a first signal output terminal 16, and multiple daisy-chain ports 17. The battery pack 1 is connected to other battery packs 1 via the first power transmission positive terminal 11 and the first power transmission negative terminal 12. The CMU 13 receives bypass commands sent by the BMU module 31. The first control switch 14 is connected between the first power transmission positive terminal 11 and the first power transmission negative terminal 12. The first control switch 14 is electrically connected to the CMU 13 and can respond to bypass commands, thereby disconnecting the first power transmission positive terminal 11 and the first power transmission negative terminal 12.

[0057] The first signal input terminal 15 and the first signal output terminal 16 are used for signal transmission. After receiving the bypass command sent by the BMU module 31, the CMU unit 13 controls the level of the first signal output terminal 16 to rise, thereby controlling the bypass device 2 to operate. Figure 1 As shown, COMHP, COMHN, COMLP, and COMLN are all daisy-chain ports 17. Daisy-chain ports 17 are mainly used for communication. The BMU module 31 sends bypass commands to the CMU unit 13 through daisy-chain ports 17.

[0058] Each bypass device 2 includes a bypass control board 21, a first branch 22, a second branch 25, a second signal input terminal 28 electrically connected to the bypass control board 21, and a second signal output terminal 29 electrically connected to the bypass control board 21. Specifically, the second signal input terminal 28 is electrically connected to the first signal output terminal 16, and the second signal output terminal 29 is electrically connected to the first signal input terminal 15. The bypass control board 21 communicates with the CMU unit 13 of the corresponding battery pack 1 (i.e., the lower-capacity battery pack that needs to be bypassed).

[0059] The first branch 22 is connected in parallel between the first power transmission positive terminal 11 and the first power transmission negative terminal 12 of the corresponding battery pack 1. The first branch 22 includes a second control switch 23 and a freewheeling diode 24 connected in series. The second control switch 23 is electrically connected to the bypass control board 21. In this embodiment, the freewheeling diode 24 is a fast recovery diode with a maximum rectified current of 60A and a maximum reverse working voltage of 1200V. The freewheeling diode 24 is used to prevent a short circuit caused by the simultaneous closing of the first control switch 14 and the second control switch 23. The battery system also uses the freewheeling diode 24 as a freewheeling device to bypass the battery pack without changing the operating state, thus achieving balance between the battery packs. The second branch 25 is connected in parallel between the first power transmission positive terminal 11 and the first power transmission negative terminal 12 of the corresponding battery pack 1. The second branch 25 includes a third control switch 26 and a fuse 27 connected in series. The third control switch 26 is electrically connected to the bypass control board 21.

[0060] The second signal input terminal 28 and the second signal output terminal 29 are used for signal transmission. After the second control switch 23 is closed, the bypass control board 21 controls the level of the second signal output terminal 29 to rise, thereby sending the closing signal of the second control switch 23 to the CMU unit 13.

[0061] like Figure 3 As shown, the second control switch 23 is provided with a second contact assembly 231, which includes a second drive contact 2311 and a second feedback contact 2312. The second drive contact 2311 is used to receive signals from the bypass control board 21 and drive the second control switch 23 to open or close. The second feedback contact 2312 is used to provide feedback to the bypass control board 21 on the opening or closing status of the second control switch 23. The third control switch 26 is provided with a third contact assembly 261, which includes a third drive contact 2611 and a third feedback contact 2612. By adding contacts to the second control switch 23 and the third control switch 26, the closing of the switch can be driven and fed back in real time, preventing open circuits or short circuits and improving the safety of the entire battery system.

[0062] The high-voltage control box 3 includes a second power transmission positive terminal 32 and a second power transmission negative terminal 33 for receiving power released from the battery pack 1. The high-voltage control box 3 is connected to the downstream photovoltaic inverter via the second power transmission positive terminal 32 and the second power transmission negative terminal 33. The high-voltage control box 3 also includes a resonant circuit 34, which is electrically connected to the first power transmission positive terminal 11, the first power transmission negative terminal 12, the second power transmission positive terminal 32, and the second power transmission negative terminal 33. The resonant circuit 34 is added to the high-voltage control box 3 to prevent voltage surges from affecting the downstream inverter.

[0063] In this embodiment, multiple battery packs 1 are connected in series. The first power transmission negative terminal 12 of battery pack 1 is electrically connected to the first power transmission positive terminal 11 of the next battery pack 1. The first power transmission positive terminal 11 of the first battery pack 1 is electrically connected to the second power transmission positive terminal 32 of the high-voltage control box 3. The first power transmission negative terminal 12 of the last battery pack 1 is electrically connected to the second power transmission negative terminal 33 of the high-voltage control box 3. In other embodiments, multiple battery packs 2 may also be connected in parallel, which is not limited here.

[0064] The following is a detailed introduction to the control methods of the battery system of residential photovoltaic energy storage equipment:

[0065] The battery system includes main circuit mode and bypass mode.

[0066] like Figure 4 As shown, when the battery system switches from main circuit mode to bypass mode, the control method includes:

[0067] S1. The high voltage control box 3 detects the capacity of multiple battery packs 1 through the BMU module 31 and determines whether the capacity of each battery pack 1 is lower than the set value. If the BMU module 31 detects that the capacity of a certain battery pack 1 is lower than the set value, it jumps to step S2. If not, it continues to detect.

[0068] S2, BMU module 31 sends a bypass command to CMU unit 13 through the daisy link port of the corresponding battery pack 1;

[0069] After receiving the bypass command, S3 and CMU unit 13 control the level of the first signal output terminal 16 to rise, thereby controlling the bypass device 2 to enter the working state.

[0070] S4. The bypass control board 21 controls the second control switch 23 to close and controls the level of the second signal output terminal 29 to rise, so that the CMU unit 13 receives the closing signal of the second control switch 23.

[0071] S5. After receiving the closing signal of the second control switch 23, the CMU unit 13 controls the first control switch 14 to open and reduces the voltage value between the corresponding first power transmission positive terminal 11 and the first power transmission negative terminal 12 to less than or equal to the target voltage value.

[0072] S6. The bypass control board 21 detects whether the voltage value between the first power transmission positive terminal 11 and the first power transmission negative terminal is less than or equal to the target voltage value. If yes, it jumps to step S7; otherwise, it continues to detect.

[0073] S7. Control the third control switch 26 to close.

[0074] like Figure 5 As shown, when the battery system switches from bypass mode to main circuit mode, the control method includes:

[0075] S8. The high voltage control box 3 detects the capacity of the bypass battery pack 1 through the BMU module 31 and determines whether the capacity of the bypass battery pack 1 is consistent with the capacity of other battery packs 1. If yes, it jumps to step S9; otherwise, it continues to detect.

[0076] S9, BMU module 31 sends a parallel connection command to CMU unit 13 through the daisy link port 17 of the corresponding battery pack 1;

[0077] After receiving the parallel line command, S10 and CMU unit 13 control the level of the first signal output terminal 16 to decrease, thereby controlling the bypass device 2 to enter the ready-to-exit state.

[0078] S11, the bypass control board 21 controls the third control switch 26 to open and controls the level of the second signal output terminal 29 to decrease, so that the CMU unit 13 receives the closing signal of the third control switch 26.

[0079] After receiving the closing signal of the third control switch 26, S12 and CMU unit 13 control the first control switch 14 to close.

[0080] S13. The bypass control board 21 detects whether the voltage value between the first power transmission positive terminal 11 and the first power transmission negative terminal 12 is greater than the target voltage value. If yes, it jumps to step S14; otherwise, it continues to detect.

[0081] S14. Control the second control switch 23 to disconnect.

[0082] As shown in Tables 1, 2, 3, and 4, and Figure 3 As shown, Tables 1 and 2 are the internal signal logic tables of the bypass device 2, and Tables 3 and 4 are the internal signal logic tables of the CMU unit 13. K1, K2, and K3 are the first control switch 14, the second control switch 23, and the third control switch 26, respectively. U = 2V indicates that the voltage between the first power transmission positive terminal 11 and the first power transmission negative terminal 12 is equal to the target voltage value. DI1:H indicates that the second signal input terminal 28 is at a high level, DI1:L indicates that the second signal input terminal 28 is at a low level, DO2:H indicates that the second signal output terminal 29 is at a high level, and DO2:L indicates that the second signal output terminal 29 is at a low level. The input or output levels are TTL levels.

[0083] Table 1

[0084] DI1:H K2 drive closed, K3 drive closed K2 drive closed, K3 drive open. DI1:L K2 drive closed, K3 drive open. K2 driver disconnected, K3 driver disconnected

[0085] Table 2

[0086] K2 closed state, K3 closed state DO2:H DO2:H K2 closed, K3 open DO2:H DO2:L K2 disconnected, K3 disconnected DO2:L DO2:L

[0087] Table 3

[0088] DI2:H K1 driver disconnected N / A DI2:L K1 drives closure N / A

[0089] Table 4

[0090] DI1:L Non-bypass mode

[0091] In summary, the battery system of the residential photovoltaic energy storage device in this embodiment has the following advantages:

[0092] 1. By connecting a bypass device in parallel to each battery pack, when the BMU module detects that a certain battery pack has a low capacity, it sends a bypass command to that battery pack. Without affecting the discharge of other battery packs, the bypass device bypasses the battery pack, thus achieving the balance between battery packs.

[0093] 2. By using a reasonable algorithm to maximize the utilization of all battery capacity, the overall utilization rate and lifespan of the battery system are increased;

[0094] 3. By using a high-voltage diode as a freewheeling device, the battery pack can be bypassed without changing the operating state, and no disconnection from the grid is required during the battery pack discharge process;

[0095] 4. The system has a simple structure, high reliability, and operates solely through hardware circuitry, resulting in low cost;

[0096] 5. By adding contacts to the second and third control switches, the closing of the switches can be driven and fed back in real time, preventing open circuits or short circuits and improving the safety of the entire battery system.

[0097] 6. This battery system is suitable for use during system shutdown or discharge, and can also be used in scenarios where batteries are reused in a cascade manner, making it applicable to a wide range of scenarios.

[0098] As indicated in this specification and claims, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, and these steps and elements do not constitute an exclusive list; the method or apparatus may also include other steps or elements. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0099] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "up," "down," "left," and "right" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0100] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are preferred embodiments. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and they should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made according to the principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A battery system for a residential photovoltaic energy storage device, comprising multiple battery packs connected in series or parallel and a high-voltage control box with a BMU module, wherein the BMU module is used to issue a bypass command to a battery pack when it detects that the capacity of a certain battery pack is low, characterized in that, Each of the battery packs is connected in parallel with a bypass device; Each of the battery packs includes: The battery pack is connected to other battery packs via the first power transmission positive terminal and the first power transmission negative terminal. The CMU unit is used to receive bypass instructions sent by the BMU module. Each battery pack also includes multiple daisy-chain ports, through which the BMU module sends the bypass instructions to the CMU unit. A first control switch is connected between the first power transmission positive terminal and the first power transmission negative terminal. The first control switch is electrically connected to the CMU unit and can disconnect the first power transmission positive terminal and the first power transmission negative terminal in response to the bypass command. Each of the bypass devices includes: A bypass control board, which is used to communicate with the CMU unit of the corresponding battery pack; The first branch is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack. The first branch includes a second control switch and a freewheeling diode connected in series. The second control switch is electrically connected to the bypass control board. The second branch is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack. The second branch includes a third control switch and a fuse connected in series. The third control switch is electrically connected to the bypass control board. The bypass control board is configured to control the level of the second signal output terminal to rise after the second control switch is closed. The second signal output terminal and the first signal input terminal are electrically connected. The CMU unit is configured to control the first control switch to open after the level of the first signal input terminal rises. The bypass control board is also configured to control the third control switch to close when the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is detected to be less than or equal to the target voltage value.

2. The battery system of the residential photovoltaic energy storage device according to claim 1, characterized in that, The second control switch is provided with a second contact assembly, and the third control switch is provided with a third contact assembly; The second contact assembly includes: The second drive contact is used to receive signals from the bypass control board and drive the opening and closing of the second control switch; The second feedback contact is used to provide feedback to the bypass control board on the opening and closing status of the second control switch; The third contact component includes: The third drive contact is used to receive signals from the bypass control board and drive the opening and closing of the third control switch; The third feedback contact is used to provide feedback to the bypass control board on the opening and closing status of the third control switch.

3. The battery system of the residential photovoltaic energy storage device according to claim 1, characterized in that, Each of the battery packs has a first signal output terminal electrically connected to the CMU unit, and each of the bypass devices has a second signal input terminal electrically connected to the bypass controller. The first signal output terminal and the second signal input terminal are electrically connected. The CMU unit is configured to control the level of the first signal output terminal to rise after receiving the bypass command sent by the BMU module, and the bypass controller is configured to control the second control switch to close after the level of the second signal input terminal rises.

4. The battery system of the residential photovoltaic energy storage device according to claim 3, characterized in that, The CMU unit is configured to pull the level of the first signal output terminal low after receiving the parallel command from the BMU module, and the bypass control board is configured to control the third control switch to open after the level of the second signal input terminal decreases, and pull the level of the second signal output terminal low after the third control switch is opened. The CMU unit is configured to control the first control switch to close after the level of the first signal input terminal decreases; the bypass control board is further configured to control the second control switch to open when the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is detected to be greater than the target voltage value.

5. The battery system of the residential photovoltaic energy storage device according to claim 1, characterized in that, The high-voltage control box includes a second power transmission positive terminal and a second power transmission negative terminal for receiving power released from the battery pack. The high-voltage control box is connected to the back-end photovoltaic inverter through the second power transmission positive terminal and the second power transmission negative terminal. Multiple battery packs are connected in series, and the first power transmission negative terminal of the battery pack is electrically connected to the first power transmission positive terminal of the next battery pack.

6. The battery system of the residential photovoltaic energy storage device according to claim 5, characterized in that, The high-voltage control box also includes a resonant circuit, which is electrically connected to the first power transmission positive terminal, the first power transmission negative terminal, the second power transmission positive terminal, and the second power transmission negative terminal.

7. The battery system of the residential photovoltaic energy storage device according to claim 1, characterized in that, The freewheeling diode is a fast recovery diode, with a maximum rectified current of 60A and a maximum reverse working voltage of 1200V.

8. A control method for a battery system of a residential photovoltaic energy storage device, characterized in that, The battery system is the battery system according to any one of claims 1 to 7, and the battery system includes a main circuit mode and a bypass mode. When the battery system switches from the main circuit mode to the bypass mode, the control method includes: S1. The high-voltage control box detects the capacity of multiple battery packs through the BMU module and determines whether the capacity of each battery pack is lower than a set value. If the BMU module detects that the capacity of a certain battery pack is lower than the set value, it jumps to step S2. Otherwise, it continues to detect. S2. The BMU module sends the bypass command to the CMU unit through the daisy-chain port of the corresponding battery pack; S3. After receiving the bypass command, the CMU unit controls the level of the first signal output terminal to increase, thereby controlling the bypass device to enter the working state. S4. The bypass control board controls the second control switch to close and controls the level of the second signal output terminal to rise, so that the CMU unit receives the closing signal of the second control switch; S5. After receiving the closing signal of the second control switch, the CMU unit controls the first control switch to open and reduces the voltage value between the corresponding first power transmission positive terminal and the first power transmission negative terminal to less than or equal to the target voltage value. S6. The bypass control board detects whether the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is less than or equal to the target voltage value. If yes, it jumps to step S7; otherwise, it continues to detect. S7. Control the third control switch to close; When the battery system switches from the bypass mode to the main circuit mode, the control method includes: S8. The high-voltage control box detects the capacity of the bypass battery pack through the BMU module and determines whether the capacity of the bypass battery pack is consistent with the capacity of the other battery packs. If yes, it jumps to step S9; otherwise, it continues to detect. S9. The BMU module sends a parallel connection command to the CMU unit through the daisy-chain port of the corresponding battery pack; S10. After receiving the parallel connection command, the CMU unit controls the level of the first signal output terminal to decrease, thereby controlling the bypass device to enter the preparation to exit state. S11. The bypass control board controls the third control switch to open and controls the level of the second signal output terminal to decrease, so that the CMU unit receives the closing signal of the third control switch. S12. After receiving the closing signal of the third control switch, the CMU unit controls the first control switch to close. S13. The bypass control board detects whether the voltage value between the first power transmission positive terminal and the first power transmission negative terminal is greater than the target voltage value. If yes, it jumps to step S14; otherwise, it continues to detect. S14. Control the second control switch to disconnect.

Images