CN116154918A - Battery system of household photovoltaic energy storage equipment and control method thereof - Google Patents

Abstract

The invention discloses a battery system of household photovoltaic energy storage equipment and a control method thereof. The battery system comprises a plurality of battery packs which are connected in series or in parallel, a high-voltage control box with a BMU module, a plurality of bypass devices and a bypass device, wherein the BMU module is used for sending a bypass instruction to one battery pack when detecting that the capacity of the battery pack is lower; each battery pack comprises a first power transmission positive terminal, a first power transmission negative terminal, a CMU unit and a first control switch; each bypass device comprises a bypass control board, a first branch and a second branch, wherein the first branch comprises a second control switch and a freewheeling diode which are mutually connected in series, and the second branch comprises a third control switch and a fuse which are mutually connected in series. The battery system bypasses the battery packs with lower capacity through the bypass device under the condition of not influencing the discharge of other battery packs, thereby realizing the balance among the battery packs.

Description

Battery system of household photovoltaic energy storage equipment and control method thereof

Technical Field

The invention belongs to the technical field of photovoltaic inverters, and particularly relates to a battery system of household photovoltaic energy storage equipment and a control method thereof.

Background

In order to meet the requirements of high voltage and large capacity of a household photovoltaic energy storage system, single batteries often form a battery pack in a serial-parallel connection mode, and the battery packs are further used in series or in parallel connection. However, the degree of aging, state of charge, state of health, and the like of each battery pack are inconsistent during use of the battery system in charge and discharge. Along with the increase of the service time of the battery, the capacities among the battery packs are easy to be inconsistent, and the service life of the battery packs and even the whole battery system is finally shortened, and even potential safety hazards such as battery deformation, explosion and the like are caused. One solution in the energy storage field is to add an additional inter-packet equalizer for equalization, which generally requires a high-voltage-resistant and high-current power conversion device, and is high in cost, and the bypass control process of the battery system needs to change or suspend the existing working state and then bypass, so that the convenience is low, short circuit or open circuit is easy to occur, and the safety is low.

Disclosure of Invention

In view of the above technical problems, an object of the present invention is to provide an improved battery system of a household photovoltaic energy storage device and a control method thereof.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the battery system of the household photovoltaic energy storage equipment comprises a plurality of battery packs which are connected in series or in parallel, and a high-voltage control box with a BMU module, wherein the BMU module is used for sending a bypass instruction to one battery pack when detecting that the capacity of the battery pack is low, and the battery system also comprises a plurality of bypass devices, and each battery pack is connected with one bypass device in parallel;

each of the battery packs includes:

a first power transmission positive terminal and a first power transmission negative terminal, the battery pack being connected to other battery packs through the first power transmission positive terminal and the first power transmission negative terminal;

the CMU unit is used for receiving the bypass instruction sent by the BMU module;

a first control switch connected between the first power transmission positive terminal and the first power transmission negative terminal, the first control switch being electrically connected to the CMU unit and capable of disconnecting the first power transmission positive terminal and the first power transmission negative terminal in response to the bypass instruction;

each of the bypass devices includes:

a bypass control board for communicating with the CMU unit of the corresponding battery pack;

the first branch circuit is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack, and comprises a second control switch and a freewheeling diode which are mutually connected in series, and the second control switch is electrically connected with the bypass control board;

the second branch circuit is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack, and comprises a third control switch and a fuse which are mutually connected in series, and the third control switch is electrically connected with the bypass control board.

Preferably, 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:

a second driving contact for receiving the signal of the bypass control board and driving the second control switch to open and close;

a second feedback contact for feeding back the opening and closing condition of the second control switch to the bypass control board;

the third contact assembly includes:

a third driving contact for receiving the signal of the bypass control board and driving the third control switch to open and close;

and the third feedback contact is used for feeding back the opening and closing conditions of the third control switch to the bypass control panel.

Preferably, each of said battery packs has a first signal output terminal electrically connected to said CMU cell, each of said bypass devices has a second signal input terminal electrically connected to said bypass controller, said first signal output terminal and said second signal input terminal being 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 be closed after the level of the second signal input terminal rises.

Further, each of the battery packs has a first signal input terminal electrically connected to the CMU cell, 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 is raised; the bypass controller is further configured to control the third control switch to close when it is detected that a 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.

Still further, the CMU unit is configured to pull the level of the first signal output terminal low after receiving a parallel instruction of the BMU module, and the bypass control board is configured to control the third control switch to be turned off after the level of the second signal input terminal is reduced, and to pull the level of the second signal output terminal low after the third switch is turned off; the CMU unit is configured to control the first control switch to be closed after the level of the first signal input terminal is reduced; the bypass controller is further configured to control the second control switch to open when it is detected that a voltage value between the first power transmission positive terminal and the first power transmission negative terminal is greater than a target voltage value.

Preferably, the high voltage control box comprises a second power transmission positive terminal and a second power transmission negative terminal for receiving the power released by the battery pack, and the high voltage control box is connected with the back-end photovoltaic inverter through the second power transmission positive terminal and the second power transmission negative terminal; the plurality of battery packs are connected in series, and the first power transmission negative electrode terminal of the battery pack is electrically connected with the first power transmission positive electrode terminal of the next battery pack.

Preferably, the high-voltage control box further comprises a resonance circuit, and the resonance circuit is electrically connected with 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.

Preferably, each of the battery packs further includes a plurality of daisy-chain interfaces through which the BMU module sends the bypass instruction to the CMU unit.

Preferably, the freewheeling diode is a fast recovery diode, the maximum rectifying current of the freewheeling diode is 60A, and the maximum reverse operating voltage is 1200V.

A control method of a battery system of a household photovoltaic energy storage device, wherein the battery system is the battery system, the battery system comprises a main circuit mode and a bypass mode,

when the battery system is switched from the main circuit mode to the bypass mode, the control method comprises the following steps:

s1, the high-voltage control box respectively detects the capacities of a plurality of battery packs through the BMU module, judges whether the capacity of each battery pack is lower than a set value, jumps to step S2 if the BMU module detects that the capacity of one battery pack is lower than the set value, and continues to detect if the capacity of one battery pack is not lower than the set value;

s2, the BMU module sends the bypass instruction to the CMU unit through the corresponding daisy chain interface of the battery pack;

s3, after receiving the bypass instruction, the CMU unit controls the level of the first signal output terminal to rise, and further controls the bypass device to enter a working state;

s4, the bypass control board controls the second control switch to be closed, and controls the level of the second signal output terminal to rise, so that the CMU unit receives a closing signal of the second control switch;

s5, after receiving a closing signal of the second control switch, the CMU unit controls the first control switch to be opened, and reduces a voltage value between the corresponding first power transmission positive terminal and the corresponding first power transmission negative terminal to be less than or equal to a 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 smaller than or equal to the target voltage value, if yes, the step S7 is skipped, and if not, the detection is continued;

s7, controlling the third control switch to be closed;

when the battery system is switched from the bypass mode to the main circuit mode, the control method comprises the following steps:

s8, the high-voltage control box detects the capacity of a bypass battery pack through the BMU module, judges whether the capacity of the bypass battery pack is consistent with the capacities of other battery packs, if so, jumps to the step S9, and if not, continues to detect;

s9, the BMU module sends a parallel instruction to the CMU unit through the corresponding daisy chain interface of the battery pack;

s10, after receiving the parallel instruction, the CMU unit controls the level of the first signal output terminal to be reduced, and further controls the bypass device to enter a ready-to-exit state;

s11, the bypass control board controls the third control switch to be opened, and controls the level of the second signal output terminal to be reduced, so that the CMU unit receives a closing signal of the third control switch;

s12, after receiving a closing signal of the third control switch, the CMU unit controls the first control switch to be closed;

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 larger than the target voltage value, if so, the step S14 is skipped, and if not, the detection is continued;

s14, controlling the second control switch to be turned off.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

according to the battery system of the household photovoltaic energy storage equipment, each battery pack is connected with the bypass device in parallel, when the BMU module detects that the capacity of one battery pack is lower, a bypass instruction is sent to the battery pack, and the battery packs are bypassed through the bypass device under the condition that discharging of other battery packs is not affected, so that balance among the battery packs is achieved. The battery system utilizes all battery capacities to the maximum through a reasonable algorithm, and the overall utilization rate and the service life of the battery system are increased. The system uses the high-voltage diode as a follow current device, so that the battery pack is bypassed under the condition of not changing the working state, and the off-grid permission is not needed in the discharging process of the battery pack. The system has the advantages of simple structure, high reliability, low cost and operation completion by only hardware circuits.

Drawings

In order to more clearly illustrate the technical solutions of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic connection diagram of a battery system of a household photovoltaic energy storage device according to an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating the connection of the inside of a high voltage control box according to an embodiment of the present invention;

FIG. 3 is a schematic block diagram of the interior of the bypass control board in accordance with an embodiment of the present invention;

FIG. 4 is a flowchart of a control method for switching a battery system from a main circuit mode to a bypass mode according to an embodiment of the present invention;

FIG. 5 is a flow chart of a control method for switching a battery system from a bypass mode to a main circuit mode in an embodiment of the invention;

1, a battery pack; 11. a first power transmission positive terminal; 12. a first power transmission negative terminal; 13. a CMU unit; 14. a first control switch; 15. a first signal input terminal; 16. a first signal output terminal; 17. a daisy chain interface; 2. a bypass device; 21. a bypass control board; 22. a first branch; 23. a second control switch; 231. a second contact assembly; 2311. a second drive contact; 2312. a second feedback contact; 24. a freewheeling diode; 25. a second branch; 26. a third control switch; 261. a third contact assembly; 2611. a third drive contact; 2612. a third feedback contact; 27. a fuse; 28. a second signal input terminal; 29. a second signal output terminal; 3. a high pressure control box; 31. a BMU module; 32. a second power transmission positive terminal; 33. a second power transmission negative terminal; 34. a resonant circuit.

Detailed Description

Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art. The description of these embodiments is provided to assist understanding of the present invention, but is not intended to limit the present invention. In addition, technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

As shown in fig. 1 to 3, the battery system of the household photovoltaic energy storage apparatus in the present embodiment includes a plurality of battery packs 1 (i.e., pack1, pack2 … pack n), a bypass device 2, and a high-voltage control box 3, which are connected in series or in parallel with each other. Each battery pack1 is connected in parallel with a bypass device 2. The high voltage control box 3 has a BMU module (battery management unit, battery management module) 31, and the BMU module 31 is configured to issue a bypass command to a certain battery pack1 when it is detected that the capacity of the battery pack1 is low. The battery pack1 is used for storing direct current generated by the photovoltaic panel, and after receiving a discharging instruction, the stored electric energy is supplied to the photovoltaic inverter through the high-voltage control box 3, converted into alternating current and then fed back to a power grid or an alternating current load.

Specifically, each battery pack1 includes a CMU unit (communication management unit ) 13, a first power transmission positive terminal 11 electrically connected to the CMU unit 13, a second power transmission negative terminal 12 electrically connected to the CMU unit 13, a first control switch 14, a first signal input terminal 15, a first signal output terminal 16, and a plurality of daisy-chain interfaces 17. The battery pack1 is connected to other battery packs 1 via a first power transmission positive electrode terminal 11 and a first power transmission negative electrode terminal 12. The CMU unit 13 is configured to receive a bypass instruction 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, and the first control switch 14 is electrically connected to the CMU unit 13 and is capable of responding to a bypass command, so as to disconnect the first power transmission positive terminal 11 and the first power transmission negative terminal 12.

The first signal input terminal 15 and the first signal output terminal 16 are used for signal transmission. After the CMU unit 13 receives 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, and further controls the bypass device 2 to operate. As shown in fig. 1, COMHP, COMHN, COMLP and COMLN are both daisy-chain interfaces 17, the daisy-chain interfaces 17 being primarily used for communication, and the BMU module 31 sends bypass instructions to the CMU unit 13 via the daisy-chain interfaces 17.

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. The second signal input terminal 28 is electrically connected to the first signal output terminal 16, and the second signal output terminal 9 is electrically connected to the first signal input terminal 15. Specifically, the bypass control board 21 is used to communicate with the CMU unit 13 of the corresponding battery pack1 (i.e., the battery pack that has a low capacity and needs to be bypassed).

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 comprises a second control switch 23 and a freewheeling diode 24 connected in series with each other. The second control switch 23 is electrically connected to the bypass control board 21. The freewheeling diode 24 in this embodiment is a fast recovery diode, the maximum rectifying current is 60A, and the maximum reverse operating voltage is 1200V, and the freewheeling diode 24 is used to prevent the first control switch 14 and the second control switch 23 from being closed at the same time to cause a short circuit. The battery system also allows for bypass of the battery packs without changing the operating conditions by freewheeling diode 24 as a freewheeling device, achieving balance among 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 with each other, and the third control switch 26 is electrically connected to the bypass control board 21.

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, and further sends a closing signal of the second control switch 23 to the CMU unit 13.

As shown in fig. 3, the second control switch 23 is provided with a second contact assembly 231, and the second contact assembly 231 includes a second driving contact 2311 and a second feedback contact 2312. The second driving contact 2311 is used for receiving a signal of the bypass control board 21 and driving the second control switch 23 to open and close. The second feedback contact 2312 is used to feed back the opening and closing condition of the second control switch 23 to the bypass control board 21. A third control switch 26 is provided with a third contact assembly 261, the third contact assembly 261 including a third drive contact 2611 and a third feedback contact 2612. By additionally arranging the contacts on the second control switch 23 and the third control switch 26, the switch can be driven and fed back in real time, the occurrence of open circuit or short circuit is prevented, and the safety of the whole battery system is improved.

The high-voltage control box 3 includes a second power transmission positive terminal 32 and a second power transmission negative terminal 33 for receiving the electric power discharged from the battery pack 1. The high-voltage control box 3 is connected to the back-end photovoltaic inverter through a second power transmission positive terminal 32 and a second power transmission negative terminal 33. The high-voltage control box 3 further includes a resonance circuit 34, and the resonance circuit 34 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. A resonant circuit 34 is added in the high-voltage control box 3 to prevent the voltage abrupt change from affecting the back-end inverter.

In this embodiment, the plurality of battery packs 1 are connected in series with each other, the first power transmission negative electrode terminal 12 of the battery pack1 is electrically connected to the first power transmission positive electrode terminal 11 of the next battery pack1, the first power transmission positive electrode terminal 11 of the first battery pack1 is electrically connected to the second power transmission positive electrode terminal 32 of the high voltage control box 3, and the first power transmission negative electrode terminal 12 of the last battery pack1 is electrically connected to the second power transmission negative electrode terminal 33 of the high voltage control box 3. In other embodiments, a plurality of battery packs 2 may be connected in parallel, which is not limited herein.

The following specifically describes a control method of a battery system of a household photovoltaic energy storage device:

the battery system includes a main circuit mode and a bypass mode,

as shown in fig. 4, when the battery system is switched from the main circuit mode to the bypass mode, the control method includes:

s1, the high-voltage control box 3 respectively detects the capacities of a plurality of battery packs 1 through the BMU module 31, judges whether the capacity of each battery pack1 is lower than a set value, jumps to step S2 if the BMU module 31 detects that the capacity of one battery pack1 is lower than the set value, and continues to detect if not;

s2, the BMU module 31 sends a bypass instruction to the CMU unit 13 through the daisy-chain interface of the corresponding battery pack 1;

s3, after receiving a bypass instruction, the CMU unit 13 controls the level of the first signal output terminal 16 to rise, so as to control the bypass device 2 to enter a working state;

s4, the bypass control board 21 controls the second control switch 23 to be closed, and controls the level of the second signal output terminal 29 to rise, so that the CMU unit 13 receives a closing signal of the second control switch 23;

s5, after receiving a closing signal of the second control switch 23, the CMU unit 13 controls the first control switch 14 to be opened and reduces the voltage value between the corresponding first power transmission positive terminal 11 and the corresponding first power transmission negative terminal 12 to be less than or equal to a target voltage value;

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 smaller than or equal to a target voltage value, if yes, the step S7 is skipped, and if not, the detection is continued;

and S7, controlling the third control switch 26 to be closed.

As shown in fig. 5, when the battery system is switched from the bypass mode to the main circuit mode, the control method includes:

s8, the high-voltage control box 3 detects the capacity of the bypass battery pack1 through the BMU module 31, judges whether the capacity of the bypass battery pack1 is consistent with the capacity of other battery packs 1, if so, jumps to the step S9, and if not, continues to detect;

s9, the BMU module 31 sends a parallel instruction to the CMU unit 13 through the daisy chain interface 17 of the corresponding battery pack 1;

s10, after receiving a parallel instruction, the CMU unit 13 controls the level of the first signal output terminal 16 to be reduced, and further controls the bypass device 2 to enter a ready-to-exit state;

s11, the bypass control board 21 controls the third control switch 26 to be opened, and controls the level of the second signal output terminal 29 to be reduced, so that the CMU unit 13 receives a closing signal of the third control switch 26;

s12, after the CMU unit 13 receives a closing signal of the third control switch 26, the first control switch 14 is controlled to be closed;

s13, detecting whether the voltage value between the first power transmission positive terminal 11 and the first power transmission negative terminal 12 is larger than a target voltage value or not by the bypass control board 21, if so, jumping to the step S14, and if not, continuing to detect;

and S14, controlling the second control switch 23 to be opened.

As shown in table 1, table 2, table 3, table 4 and fig. 3, wherein table 1 and table 2 are internal signal logic tables of the bypass device 2, and table 3 and table 4 are 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 value 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 inputs a high level, DI1: l denotes that the second signal input terminal 28 inputs a low level, DO2: h denotes that the second signal output terminal 29 outputs a high level, DO2: l denotes that the second signal output terminal 29 outputs a low level, wherein the level of input or output is a TTL level.

TABLE 1

	U＜2V	U≥2V
			DI1:H	K2-driven closure, K3-driven closure	K2 drive closed, K3 drive open
DI1:L	K2 drive closed, K3 drive open	K2 drive off, K3 drive off

TABLE 2

	DI1:H	DI1:L
			K2 closed state, K3 closed state	DO2:H	DO2:H
K2 closed state, K3 open state	DO2:H	DO2:L
			K2 off state, K3 off state	DO2:L	DO2:L

TABLE 3 Table 3

	Bypass mode	Non-bypass mode
			DI2:H	K1 drive disconnect	N/A
DI2:L	K1 drive closure	N/A

TABLE 4 Table 4

DI1:H	Bypass mode
		DI1:L	Non-bypass mode

In summary, the battery system of the household photovoltaic energy storage device in the embodiment has the following advantages:

1. by connecting each battery pack in parallel with a bypass device, when the BMU module detects that the capacity of one battery pack is lower, a bypass instruction is sent to the battery pack, and the battery packs are bypassed through the bypass device under the condition that the discharging of other battery packs is not influenced, so that balance among the battery packs is realized;

2. all battery capacities are utilized to the maximum degree through a reasonable algorithm, so that the overall utilization rate and the service life of the battery system are increased;

3. the high-voltage diode is used as a follow current device, so that the battery pack is bypassed under the condition of not changing the working state, and the off-grid permission is not needed in the discharging process of the battery pack;

4. the system has the advantages of simple structure, high reliability, low cost and operation completion by only hardware circuits;

5. the contacts are additionally arranged on the second control switch and the third control switch, so that the switch can be driven and fed back in real time, the occurrence of open circuit or short circuit is prevented, and the safety of the whole battery system is improved;

6. the battery system is suitable for the shutdown or discharge process of the system, can be also suitable for the scene of echelon battery utilization, and has wide application scene.

As used in this specification and in the claims, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus. The term "and/or" as used herein includes any combination of one or more of the associated listed items.

It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly or indirectly fixed or connected to the other feature. Further, the descriptions of the upper, lower, left, right, etc. used in the present invention are merely with respect to the mutual positional relationship of the constituent elements of the present invention in the drawings.

The above-described embodiments are provided for illustrating the technical concept and features of the present invention, and are intended to be preferred embodiments for those skilled in the art to understand the present invention and implement the same according to the present invention, not to limit the scope of the present invention. All equivalent changes or modifications made according to the principles of the present invention should be construed to be included within the scope of the present invention.

Claims (10)

1. The battery system of the household photovoltaic energy storage equipment comprises a plurality of battery packs which are connected in series or in parallel and a high-voltage control box with a BMU module, wherein the BMU module is used for sending a bypass instruction to one battery pack when detecting that the capacity of the battery pack is low;

each of the battery packs includes:

a first power transmission positive terminal and a first power transmission negative terminal, the battery pack being connected to other battery packs through the first power transmission positive terminal and the first power transmission negative terminal;

the CMU unit is used for receiving the bypass instruction sent by the BMU module;

a first control switch connected between the first power transmission positive terminal and the first power transmission negative terminal, the first control switch being electrically connected to the CMU unit and capable of disconnecting the first power transmission positive terminal and the first power transmission negative terminal in response to the bypass instruction;

each of the bypass devices includes:

a bypass control board for communicating with the CMU unit of the corresponding battery pack;

the first branch circuit is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack, and comprises a second control switch and a freewheeling diode which are mutually connected in series, and the second control switch is electrically connected with the bypass control board;

the second branch circuit is connected in parallel between the first power transmission positive terminal and the first power transmission negative terminal of the corresponding battery pack, and comprises a third control switch and a fuse which are mutually connected in series, and the third control switch is electrically connected with the bypass control board.

2. The battery system of a household photovoltaic energy storage device of claim 1, wherein the second control switch has a second contact assembly thereon and the third control switch has a third contact assembly thereon;

the second contact assembly includes:

a second driving contact for receiving the signal of the bypass control board and driving the second control switch to open and close;

a second feedback contact for feeding back the opening and closing condition of the second control switch to the bypass control board;

the third contact assembly includes:

a third driving contact for receiving the signal of the bypass control board and driving the third control switch to open and close;

and the third feedback contact is used for feeding back the opening and closing conditions of the third control switch to the bypass control panel.

3. The battery system of a household photovoltaic energy storage apparatus of claim 1, wherein each of said battery packs has a first signal output terminal electrically connected to said CMU cell, each of said bypass devices has a second signal input terminal electrically connected to said bypass controller, said first signal output terminal and said second signal input terminal 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 be closed after the level of the second signal input terminal rises.

4. A battery system for a household photovoltaic energy storage apparatus according to claim 3, wherein each of said battery packs has a first signal input terminal electrically connected to said CMU cell, each of said bypass devices has a second signal output terminal electrically connected to said bypass controller, said second signal output terminal electrically connected to said 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 is raised; the bypass controller is further configured to control the third control switch to close when it is detected that a 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.

5. The battery system of a household photovoltaic energy storage device of claim 4, wherein the CMU unit is configured to pull the level of the first signal output terminal low upon receiving a parallel instruction of the BMU module, the bypass control board is configured to control the third control switch to open upon a decrease in the level of the second signal input terminal, and to pull the level of the second signal output terminal low upon an opening of the third switch; the CMU unit is configured to control the first control switch to be closed after the level of the first signal input terminal is reduced; the bypass controller is further configured to control the second control switch to open when it is detected that a voltage value between the first power transmission positive terminal and the first power transmission negative terminal is greater than a target voltage value.

6. The battery system of a household photovoltaic energy storage device of claim 1, wherein the high voltage control box comprises a second power transmission positive terminal and a second power transmission negative terminal for receiving power released by the battery pack, the high voltage control box being connected by the second power transmission positive terminal and the second power transmission negative terminal and a back-end photovoltaic inverter; the plurality of battery packs are connected in series, and the first power transmission negative electrode terminal of the battery pack is electrically connected with the first power transmission positive electrode terminal of the next battery pack.

7. The battery system of a household photovoltaic energy storage device of claim 1, wherein the high voltage control box further comprises a resonant circuit, the resonant circuit being electrically connected to the first power transfer positive terminal, the first power transfer negative terminal, the second power transfer positive terminal, and the second power transfer negative terminal.

8. The battery system of a consumer photovoltaic energy storage device of claim 1, wherein each of the battery packs further comprises a plurality of daisy-chain interfaces through which the BMU module sends the bypass instructions to the CMU unit.

9. The battery system of a household photovoltaic energy storage device of claim 1, wherein the freewheeling diode is a fast recovery diode, the freewheeling diode has a maximum rectified current of 60A and a maximum reverse operating voltage of 1200V.

10. A control method of a battery system of a household photovoltaic energy storage device, characterized in that the battery system is the battery system of any one of claims 1-9, the battery system comprises a main circuit mode and a bypass mode,

when the battery system is switched from the main circuit mode to the bypass mode, the control method comprises the following steps:

s1, the high-voltage control box respectively detects the capacities of a plurality of battery packs through the BMU module, judges whether the capacity of each battery pack is lower than a set value, jumps to step S2 if the BMU module detects that the capacity of one battery pack is lower than the set value, and continues to detect if the capacity of one battery pack is not lower than the set value;

s2, the BMU module sends the bypass instruction to the CMU unit through the corresponding daisy chain interface of the battery pack;

s3, after receiving the bypass instruction, the CMU unit controls the level of the first signal output terminal to rise, and further controls the bypass device to enter a working state;

s4, the bypass control board controls the second control switch to be closed, and controls the level of the second signal output terminal to rise, so that the CMU unit receives a closing signal of the second control switch;

s5, after receiving a closing signal of the second control switch, the CMU unit controls the first control switch to be opened, and reduces a voltage value between the corresponding first power transmission positive terminal and the corresponding first power transmission negative terminal to be less than or equal to a 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 smaller than or equal to the target voltage value, if yes, the step S7 is skipped, and if not, the detection is continued;

s7, controlling the third control switch to be closed;

when the battery system is switched from the bypass mode to the main circuit mode, the control method comprises the following steps:

s8, the high-voltage control box detects the capacity of a bypass battery pack through the BMU module, judges whether the capacity of the bypass battery pack is consistent with the capacities of other battery packs, if so, jumps to the step S9, and if not, continues to detect;

s9, the BMU module sends a parallel instruction to the CMU unit through the corresponding daisy chain interface of the battery pack;

s10, after receiving the parallel instruction, the CMU unit controls the level of the first signal output terminal to be reduced, and further controls the bypass device to enter a ready-to-exit state;

s11, the bypass control board controls the third control switch to be opened, and controls the level of the second signal output terminal to be reduced, so that the CMU unit receives a closing signal of the third control switch;

s12, after receiving a closing signal of the third control switch, the CMU unit controls the first control switch to be closed;

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 larger than the target voltage value, if so, the step S14 is skipped, and if not, the detection is continued;

s14, controlling the second control switch to be turned off.

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