CN116683559A - Energy storage system, energy storage device and energy storage management system - Google Patents

Abstract

The application provides an energy storage system, energy storage equipment and an energy storage management system. The energy storage system comprises at least one battery cluster, a first controller and a DC/AC conversion circuit; the battery cluster is connected with a first end of the DC/AC conversion circuit, a second end of the DC/AC conversion circuit is used for being connected with a grid connection point, and the DC/AC conversion circuit is used for being connected with a power grid or a load through the grid connection point; the battery cluster comprises N battery packs, wherein the N battery packs are connected in series, and N is an integer greater than or equal to 2; the first controller is used for controlling the serial number of the battery packs and other battery packs in the same battery cluster so that the output voltage of the battery cluster is larger than the voltage peak value of the second end of the DC/AC conversion circuit. By adopting the embodiment of the application, the working efficiency, capacity and availability of the energy storage system can be improved.

Description

Energy storage system, energy storage equipment and energy storage management system

technical field

The present application relates to the technical field of battery energy storage, and relates to an energy storage system, an energy storage device and an energy storage management system.

Background technique

With the gradual increase in the proportion of new energy sources, the configuration of energy storage systems is becoming increasingly important. The energy storage system can realize grid frequency regulation and peak regulation through charging and discharging control. The energy storage system is mainly composed of battery clusters, and the power conversion system (PCS) is used to convert AC to DC to control the charging and discharging process of the battery clusters, and can directly supply power to AC loads in the absence of a grid. Since one end of the energy storage converter is used to connect to the grid, the voltage at the end of the energy storage converter connected to the grid will fluctuate in a large range during the charging and discharging process. If the voltage is greater than the voltage that the battery cluster can provide, it will As a result, the energy storage converter cannot work, downtime occurs, and the working efficiency of the energy storage system is reduced.

The existing technology is to introduce a DC/DC converter in each battery pack. The DC/DC converters of each battery pack in the same battery cluster share a set of buses, and the DC/DC converters followed by each battery pack are used to realize energy. To manage, the DC/DC converter boosts the terminal voltage of each battery cluster to the same DC voltage as the DC bus voltage. However, since the voltage of the DC bus is much higher than the port voltage of each battery cluster, the step-up ratio of the DC/DC converter is very high, resulting in low efficiency and high cost of the DC/DC converter, which in turn reduces the efficiency of the energy storage system. The energy storage efficiency is high, and the cost of the energy storage system is increased. Additional wiring is required to realize the energy transfer between different battery packs. The wiring complexity is high and the probability of error is high, which makes the delivery of the energy storage system difficult and the delivery quality cannot be guaranteed. Guarantee, poor applicability.

Contents of the invention

The application provides an energy storage system, an energy storage device and an energy storage management system, which ensure that the output voltage of the battery cluster is always greater than the voltage of the second terminal of the DC/AC conversion circuit by adjusting the number of battery packs connected in series in each battery cluster in real time The peak value makes the voltage difference on both sides of the DC/AC conversion circuit smaller, and the output voltage of the battery cluster is maintained at a higher point, which can improve the working efficiency, capacity and availability of the energy storage system, and can realize the energy storage of each battery in the energy storage system. Cell balancing of packs and battery clusters.

In the first aspect, the present application provides an energy storage system, the energy storage system includes at least one battery cluster, a first controller, and a DC/AC conversion circuit; the battery cluster is connected to the first end of the DC/AC conversion circuit, and the DC/AC conversion The second end of the circuit is used to connect the grid-connected point, and the DC/AC conversion circuit is used to connect the grid or load through the grid-connected point; the battery cluster includes N battery packs, and the N battery packs are connected in series, where N is an integer greater than or equal to 2 ; The first controller is used to control the number of battery packs connected in series, so that the output voltage of the battery pack is greater than the peak voltage of the second terminal of the DC/AC conversion circuit.

In this embodiment, the first controller can adjust the number of battery packs in series in the battery cluster in real time to ensure that the output voltage of the battery cluster is greater than the peak voltage of the second terminal of the DC/AC conversion circuit, so that the voltage on both sides of the DC/AC conversion circuit The pressure difference is small, so as to ensure that the energy storage system can work stably without downtime, can improve the work efficiency, capacity and availability of the energy storage system, and can increase the power generation of the battery cluster, thereby increasing the voltage of the energy storage system on the grid Energy storage efficiency during fluctuations, and there is no need to introduce a DC/DC conversion circuit between the battery cluster and the DC/AC conversion circuit, no boost operation is required, the cost of the energy storage system is reduced, and the applicability is strong.

In a possible implementation manner, the energy storage system includes N first switches and N second switches, and the N first switches and N second switches correspond to the battery packs one by one, and each battery pack is connected in series with a first switch. Switches, each battery pack connected in series and the first switch are connected in parallel with a second switch; the first controller is used to control the closing or opening of the first switch and the second switch corresponding to each battery pack to realize the connection between the battery pack and the same battery cluster The series connection or bypass of other battery packs in the same battery cluster; when the first switch is closed and the second switch is open, the battery packs corresponding to the first switch and the second switch are connected in series with other battery packs in the same battery cluster; When the first switch is turned off and the second switch is turned on, the battery pack corresponding to the first switch and the second switch is bypassed.

In this embodiment, each battery pack is provided with a corresponding first switch and a corresponding second switch, and by controlling the closing and opening of the first switch and the second switch, the corresponding battery pack and the batteries in the same battery cluster are controlled. Other battery packs are connected in series or bypass the corresponding battery packs, so that while bypassing the battery packs that need to be bypassed, the main circuit of charging and discharging of the energy storage system is not cut off, so that the output voltage of the battery pack can be stabilized at a higher level. Points to improve the power generation and charging and discharging efficiency of the energy storage system.

In a possible implementation manner, when the difference between the output voltage of the battery cluster and the voltage peak value of the second terminal of the DC/AC conversion circuit is greater than or equal to the first voltage threshold, the first controller is configured to: sequentially controlling the corresponding first switches of all battery packs in each battery pack to be disconnected, and the second switch to be closed to bypass each battery pack in turn, wherein the battery pack includes one or more battery packs; the first controller It is also used to control the first switch in the other battery packs of the unbypassed battery packs in the battery cluster to be closed, the second switch to be opened, and the other battery packs of the unbypassed battery packs in the battery cluster to be converted by DC/AC The circuit is used to realize the charging and discharging of the battery cluster.

The energy storage system provided by this embodiment does not need a DC/DC conversion circuit to boost the battery cluster, so the battery cluster included in the energy storage system provided by this application can accommodate more battery packs, thereby increasing the capacity of the energy storage system . The voltage on the grid side is AC voltage, and the grid voltage fluctuates. When the second terminal of the DC/AC conversion circuit is connected to the grid, the voltage at the second terminal of the DC/AC conversion circuit has a voltage peak. When the difference between the peak voltages of the second terminal of the AC conversion circuit is greater than or equal to the first voltage threshold, at this time, there is a certain difference between the voltage output by the battery cluster and the voltage of the second terminal of the DC/AC conversion circuit. In order to avoid DC/AC The voltage difference on both sides of the AC conversion circuit is too large and unnecessary power is wasted. It is not necessary to connect all the battery packs in the battery cluster in series, and divide the battery packs in the battery cluster into multiple battery packs. The battery packs in each battery pack The number is the same, and the first controller is used to sequentially control the bypass of each battery pack within the first time period. The first controller controls the corresponding first switches of all battery packs in the battery pack that need to be bypassed to be turned off. The second switch is closed, each battery pack is bypassed in turn, the unbypassed battery pack is still charging and discharging normally, and the total output voltage of the unbypassed battery pack is still greater than the voltage of the second terminal of the DC/AC conversion circuit The peak value can not only ensure that the output voltage of the battery cluster is within the normal working voltage range, but also realize the power balance of the battery pack.

In a possible implementation manner, when the difference between the output voltage of the battery cluster and the voltage peak value of the second terminal of the DC/AC conversion circuit is greater than the first voltage threshold and the remaining power difference of the N battery packs is greater than or equal to the first When the power threshold is reached, the first controller is used to control the bypass time of the battery packs with different remaining power to be different so that the remaining power difference of the N battery packs is less than the first power threshold, including: when any of the N battery packs When the remaining power of the battery pack is greater than the average remaining power of the N battery packs, reduce the bypass time of the battery pack; when the remaining power of any one of the N battery packs is less than the average remaining power of the N battery packs, extend The bypass time of the battery pack, wherein the bypass time is the time when the first switch is turned off and the second switch is turned on.

In this embodiment, the power balance between the battery packs is realized by controlling the bypass time of the battery packs with different electric power to be different.

In a possible implementation manner, the energy storage system includes N second controllers, and the N second controllers are in one-to-one correspondence with the N battery packs, and the second controller is used to obtain the voltage and remaining power of the corresponding battery pack; The second controller is also used to control the opening and closing of the first switch and the second switch corresponding to the corresponding battery pack according to the instruction of the first controller, so as to control the number of series connections.

In this embodiment, each second controller monitors the status of its correspondingly connected battery pack, and the monitored data on the remaining power of the correspondingly connected battery pack is more accurate. Controls are also more accurate.

In a possible implementation, the energy storage system includes multiple battery clusters, and the multiple battery clusters are connected in parallel to the first end of the DC/AC conversion circuit. When the remaining power difference of the multiple battery clusters is greater than or equal to the second power threshold , the first controller is used to control the number of battery packs connected in series in the plurality of battery clusters so that the remaining power difference of the multiple battery clusters is less than the second power threshold.

In this embodiment, the number of battery packs connected in series in each battery cluster is controlled according to the result of the difference between the remaining power levels of the battery clusters, so as to achieve power balance among the battery clusters.

In a possible implementation manner, when multiple battery clusters are in the charging state and the remaining power of any one of the N battery packs is greater than or equal to the third power threshold, the first controller is used to control the remaining power to be greater than or equal to the third power threshold. Threshold for battery pack bypass.

In a possible implementation manner, when multiple battery clusters are in a discharging state and the remaining power of any one of the N battery packs is less than or equal to the fourth power threshold, the first controller is used to control the remaining power to be less than or equal to the fourth power threshold Threshold for battery pack bypass.

During the charging or discharging process of the energy storage system, the corresponding battery packs are controlled to bypass the battery packs whose remaining power is greater than the third power threshold when charging or the battery packs whose remaining power is less than the fourth power threshold when discharging, and others The battery packs continue to be charged or discharged, and eventually all the battery packs reach the same value. When the energy storage system is charged or discharged again, due to the balance of the battery packs, the time to complete charging or discharging is basically the same, which can realize a larger energy storage system. The backup time is long, and the utilization rate and availability of the remaining power of the energy storage system are improved.

In a possible implementation, the energy storage system includes multiple DC/AC conversion circuits, each battery cluster is connected to the DC/AC conversion circuit, and the multiple DC/AC conversion circuits are coupled to the AC bus, and the AC bus is connected to the grid connection point .

In a possible implementation manner, when the voltage at the second end of the DC/AC conversion circuit has a transient overvoltage, the first controller is used to control the first switches corresponding to the N battery packs to be closed, and the second switches to be opened. , so that N battery packs are connected in series.

In this embodiment, the output voltage of the battery cluster is increased by increasing the number of battery packs connected in series to realize high-voltage ride-through, that is, the energy storage system can still maintain normal operation and output power under the condition of transient overvoltage, preventing energy storage The system goes down when the grid side voltage fluctuates greatly.

In a possible implementation manner, the energy storage system includes a voltage detection circuit; the voltage detection circuit is used to detect the voltage of the battery cluster and the voltage of the second terminal of the DC/AC conversion circuit; the voltage detection circuit is used to output the detected voltage to first controller.

In a possible implementation manner, the energy storage system includes a fault detection circuit; the fault detection circuit is used to detect whether there is a fault in any one of the N battery packs, and instruct the first controller after detecting a fault in the battery pack The first switch controlling the failed battery pack is opened and the second switch is closed. Among them, the failure of the battery pack includes short-circuit failure, communication failure, electrolyte leakage, thermal runaway and other failures. In this embodiment, the fault is detected by the fault detection circuit, and then the faulty battery pack is bypassed to reduce the impact of the fault from spreading to other battery packs and reduce other risks caused by the fault.

In the second aspect, the embodiment of the present application provides an energy storage device. The energy storage device includes a battery pack, a first switch, a second switch, and a second controller. The battery pack includes a plurality of batteries, and the battery pack is connected in series with the first switch. , the series-connected battery pack and the first switch are connected in parallel with the second switch; the second controller is used to control the closing or opening of the first switch and the second switch to control the energy storage device to be connected in series with other energy storage devices or the energy storage device Bypass; when the first switch is closed and the second switch is open, the energy storage device is connected in series with other energy storage devices; when the first switch is open and the second switch is closed, the energy storage device is bypassed.

In a possible implementation manner in combination with the second aspect, the energy storage device is used to be connected in series with multiple other energy storage devices, and all the energy storage devices are connected in series to form an energy storage unit, and the energy storage unit is used to connect to the DC/AC conversion circuit The first end, the second end of the DC/AC conversion circuit is used to connect the grid-connected point, and the DC/AC conversion circuit is used to connect the grid or load through the grid-connected point; the second controller is used to detect that the output voltage of the energy storage unit is less than or equal to When the voltage peak value of the second terminal of the DC/AC conversion circuit is reached, the first switch in the energy storage device is controlled to be closed, and the second switch is turned off, so that the energy storage device is connected in series with other energy storage devices, so that the output of the energy storage unit The voltage is greater than the peak voltage of the second terminal of the DC/AC conversion circuit.

In the third aspect, the embodiment of the present application provides an energy storage management system. The energy storage management system includes a DC/AC conversion circuit and a first controller; the first end of the DC/AC conversion circuit is connected to a battery cluster, and the DC/AC conversion circuit The second end of the grid is used to connect the grid-connected point, and the DC/AC conversion circuit is used to connect the grid or load through the grid-connected point; the battery cluster includes N battery packs, and the N battery packs are connected in series; the first controller is used to obtain the battery cluster and DC /AC converting the voltage of the second end of the circuit, and controlling the number of battery packs connected in series, so that the output voltage of the battery pack is greater than the voltage peak value of the second end of the DC/AC converting circuit.

In a possible implementation manner in combination with the third aspect, the battery cluster includes N first switches and N second switches, and the N first switches and N second switches correspond to the battery packs one by one, and each battery pack A first switch is connected in series, and each battery pack in series is connected with the first switch in parallel with a second switch; the first controller is used to control the closing or opening of the first switch and the second switch corresponding to each battery pack to realize the connection between the battery pack and the second switch. Other battery packs in the same battery cluster are connected in series or battery packs are bypassed. When the first switch is closed and the second switch is open, the battery packs corresponding to the first switch and the second switch are connected in series with other battery packs in the same battery cluster. connection; when the first switch is open and the second switch is closed, the battery pack corresponding to the first switch and the second switch is bypassed.

For the beneficial effects of the second aspect and the third aspect, reference may be made to the description of the foregoing first aspect, and details are not repeated here.

Description of drawings

Figure 1 is a schematic structural diagram of an energy storage system;

Figure 2 is a schematic diagram of voltage fluctuations;

Fig. 3 is a schematic structural diagram of the energy storage system provided by the embodiment of the present application;

Fig. 4 is a schematic structural diagram of the energy storage system provided by the embodiment of the present application;

Fig. 5 is a schematic structural diagram of an energy storage system provided by an embodiment of the present application;

Fig. 6 is a schematic structural diagram of an energy storage system provided by an embodiment of the present application;

Fig. 7 is a schematic diagram of the working principle of the energy storage system provided by the embodiment of the present application;

Fig. 8 is a schematic diagram of the relationship curve between the state of health of the battery and the service life;

FIG. 9 to FIG. 10 are boost effect diagrams provided by the embodiments of the present application.

Detailed ways

In order to better introduce the embodiments of the present application, related concepts in the embodiments of the present application are firstly introduced below.

1. Battery control unit (BCU)

The BCU is used to monitor the voltage, temperature, current, and insulation resistance of the battery pack, control the high-voltage DC circuit relay, and estimate the state of health (SOH) and state of charge (SOC) of the battery pack.

2. Central control unit (CCU)

The CCU is used to control the battery cluster, including: battery cluster state estimation, online diagnosis and early warning, charge, discharge and pre-charge control, balance management and thermal management, etc.

3. Battery pack (PACK)

A battery pack can be composed of one or more battery cells (battery cells can be single cells, etc., and the voltage of the battery cells is usually between 2.5V and 4.2V) connected in series and parallel to form the smallest energy storage and management unit.

In the embodiments of the present application, "multiple" means two or more.

In the embodiment of the present application, the connection between A and B means the circuit connection between A and B, indicating that electrical signal transmission can be realized between A and B.

In each embodiment of the present application, if there is no special explanation and logical conflict, the terms and/or descriptions between the various embodiments are consistent and can be referred to each other. The technical features in different embodiments are based on their inherent logic Relationships can be combined to form new embodiments.

Embodiments of the present application are described below with reference to the accompanying drawings.

In order to overcome the severe intermittency problems of large-scale photovoltaic power generation and wind power generation, and with the rapid decline in battery costs, battery energy storage, due to its application flexibility, controllability and energy density, has become an The power consumption side has been developed rapidly. Whether it is large-scale photovoltaic power generation or wind power generation, the grid voltage is usually high, such as 400V to 800V AC voltage, resulting in a DC side voltage of 550V to 1500V. However, the voltage of a single battery pack is usually small, for example, the voltage of a single battery pack is usually less than 60V. In order to meet the voltage requirements of the grid, multiple battery packs are usually directly connected in series to form a battery cluster to obtain high voltage. The voltage on the grid side is an AC voltage with fluctuations. When the peak value of the grid voltage is greater than the output voltage of the battery cluster, the battery cluster cannot work.

Referring to FIG. 1 , the energy storage system 100 shown in FIG. 1 includes an energy storage unit 110 and an energy storage converter 120 . The energy storage unit 110 is connected with the energy storage converter 120 , and is charged and discharged through the energy storage converter 120 .

Exemplarily, the energy storage converter 120 may be connected to the grid 400 . The energy storage converter 120 can convert the DC power from the energy storage unit 110 to output AC power to the grid 400 to supply power to the grid 400 . Alternatively, the energy storage converter 120 may convert the AC power from the grid 400 to output DC power to the energy storage unit 110 to charge the energy storage unit 110 .

Exemplarily, the energy storage unit 110 may be a battery cluster. A battery cluster can include one or more batteries connected in series or in parallel. The battery may include, for example, a lithium-ion battery (such as a lithium iron phosphate battery or a ternary lithium battery), a lead-acid battery (or a lead-acid battery) or a sodium-ion battery, and the application does not specifically limit the type of the battery.

In a specific implementation, the above-mentioned energy storage converter 120 realizes mutual conversion between the DC voltage V _bat of the energy storage unit 110 and the voltage V _ac at one end of the energy storage converter connected to the grid, so as to realize the electric energy in the energy storage unit 110 The storage and release of the energy storage unit 110 is to realize the charging and discharging of the energy storage unit 110 . But in the process of charging and discharging, the voltage V _ac will fluctuate in a large range. For example, refer to FIG. 2 as an example. When the voltage V _bat of the energy storage unit 110 is lower than the peak voltage V _ac (for example, see the risk zone in FIG. 2 ), the energy storage converter 120 cannot work, which reduces the working efficiency of the energy storage converter 120 .

In order to solve this problem, an embodiment of the present application provides an energy storage system, which can be exemplarily referred to in FIG. 3 and FIG. 4 . The energy storage system provided by this application has a simple structure and high safety, which can improve the control flexibility of each energy storage module in the energy storage system, improve the effective utilization rate of the energy storage module, and enhance the management of the energy storage module Effectiveness, strong applicability.

The energy storage system 200 provided in the embodiment of the present application includes at least one battery cluster 201, a first controller 202, and a DC/AC conversion circuit 203; the battery cluster 201 is connected to the first end of the DC/AC conversion circuit 203, and the DC/AC conversion circuit The second end of 203 is used to connect the grid-connected point 300, and the DC/AC conversion circuit 203 is used to connect the grid 400 or the load 500 through the grid-connected point 300; the battery cluster 201 includes N battery packs, and the N battery packs are connected in series, wherein, N is an integer greater than or equal to 2; the first controller 202 is used to control the number of battery packs connected in series so that the output voltage of the battery pack 201 is greater than the peak voltage of the second terminal of the DC/AC conversion circuit 203 .

In the embodiment of the present application, the input and output of the second terminal of the DC/AC conversion circuit 203 is alternating current, and there is a voltage peak. When the output voltage of the battery cluster 201 is greater than the voltage of the second terminal of the DC/AC conversion circuit 203, the energy storage system 200 to work normally, the embodiment of the present application adjusts the output voltage of the battery cluster 201 by controlling the number of battery packs in series in the battery cluster 201, so that the output voltage of the battery cluster 201 is greater than the voltage peak value of the second terminal of the DC/AC conversion circuit 203, The output voltage of the DC/AC conversion circuit 203 is maintained at a relatively high value and is in a better working mode, which improves the working efficiency of the energy storage system 200, and does not require an additional DC/DC circuit to boost the battery cluster 201. The battery cluster 201 in the embodiment of the application can be equipped with more battery packs, which increases the capacity of the battery cluster 201 .

During specific implementation, the first controller 202 may be a general-purpose central processing unit (central processing unit, CPU), a general-purpose processor, digital signal processing (digital signal processing, DSP), application specific integrated circuits (application specific integrated circuits, ASIC), A field programmable gate array (fieldprogrammable gate array, FPGA) or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The above-mentioned processors may also be a combination to realize computing functions. For example, the first controller 202 may include one or more combinations of microprocessors, a combination of DSP and microprocessors, and the like.

In some examples, the energy storage system 200 includes N first switches and N second switches, and the N first switches and N second switches correspond to N battery packs one by one, and each battery pack is connected in series with a first switch , each battery pack is connected in parallel with a second switch; the first controller 202 is used to control the closing or opening of the first switch and the second switch corresponding to each battery pack to realize the connection between the battery pack and other battery packs in the same battery cluster Series connection or battery pack bypass; when the first switch is closed and the second switch is open, the battery pack corresponding to the first switch and the second switch is connected in series with other battery packs; when the first switch is open, the second switch is closed When , the battery pack corresponding to the first switch and the second switch is bypassed.

In this application, by setting the first switch and the second switch corresponding to the battery pack, according to the comparison result of the output voltage of the battery cluster 201 and the voltage peak value of the second terminal of the DC/AC conversion circuit 203, the access and connection of different battery packs are controlled. The bypass avoids the situation that the energy storage system 200 cannot work when the grid voltage fluctuates, and there is no need to add an additional DC/DC circuit, and there is no need to boost the battery unit, which reduces the complexity and cost of the circuit and improves the storage capacity. The availability and work efficiency of the energy system 200.

Exemplarily, the first switch and the second switch may be switching elements such as relays, IGBT tubes, and MOS tubes, which are not specifically limited in this embodiment of the present application. Moreover, the first switch and the second switch may be located inside the battery pack or outside the battery pack, and the embodiments of the present application do not specifically limit the positions of the first switch and the second switch.

It should be noted that the DC/AC conversion circuit 203 provided in the embodiment of the present application is a bidirectional DC/AC conversion circuit 203, and the DC/AC conversion circuit 203 is used to convert the DC voltage output by the battery cluster 201 into an AC voltage and output it to the power grid or The load 500 realizes the discharge of the battery cluster 201, and the DC/AC conversion circuit 203 can also convert the AC voltage output by the grid into a DC voltage to realize the charging of the battery cluster 201, so that the bidirectional DC/AC conversion circuit 203 can be fully utilized, This enables the rated output operating voltage of the bidirectional DC/AC conversion circuit 203 to be maintained at a relatively high value, and is in an optimal efficiency operating mode, thereby improving the operating efficiency of the energy storage system 200 .

It should be noted that the embodiment of the present application does not limit the number of battery clusters 201 in the energy storage system 200, which may be one battery cluster 201 or multiple battery clusters 201. For example, FIG. 5 provides 201 of the energy storage system 200, therefore, the energy storage system 200 provided in the embodiment of the present application can set the number of battery clusters 201 and battery packs according to different adaptation scenarios, and the applicable scenarios are more abundant.

It should be noted that the energy storage system 200 may include a DC/AC conversion circuit 203. As shown in FIG. 4 and FIG. The second end of the circuit 203 is connected to the grid-connection point 300 . The energy storage system 200 may also include a plurality of DC/AC conversion circuits 203. For example, as shown in FIG. , multiple DC/AC conversion circuits 203 are coupled to the AC bus, and the AC bus is connected to the grid-connection point 300 .

In some examples, when the difference between the output voltage of the battery cluster 201 and the peak voltage of the second terminal of the DC/AC conversion circuit 203 is greater than or equal to a first voltage threshold, the first controller 202 is configured to sequentially controlling the corresponding first switches of all battery packs in each battery pack to be disconnected, and the second switch to be closed to bypass each battery pack in turn, wherein the battery pack includes one or more battery packs; the first controller 202 is also used to control the first switch in the other battery packs of the battery packs not bypassed in the battery cluster 201 to be closed, the second switch to be opened, and the other battery packs of the battery packs not bypassed in the battery cluster 201 to pass through the DC /AC conversion circuit 203 to realize the charging and discharging of the battery cluster 201. When the second end of the DC/AC conversion circuit 203 is connected to the power grid, the voltage at the second end of the DC/AC conversion circuit 203 has a voltage peak, and when the output voltage of the battery pack 201 is the same as the voltage peak value at the second end of the DC/AC conversion circuit 203 When the difference between them is greater than or equal to the first voltage threshold, at this time, there is a certain difference between the voltage output by the battery cluster 201 and the voltage at the second end of the DC/AC conversion circuit 203, in order to avoid the voltage on both sides of the DC/AC conversion circuit 203 The pressure difference is too large and unnecessary power is wasted. At this time, it is not necessary to connect all the battery packs in the battery cluster 201 in series to supply power to the grid side. In this embodiment, the battery packs in the battery cluster 201 are divided into multiple battery packs. The number of battery packs in each battery pack is the same, and the first controller 202 is used to sequentially control the corresponding first switch of all battery packs in each battery pack to be turned off and the second switch to be closed in the first time period. Bypassing each battery pack, this technical solution can not only ensure that the output voltage of the battery cluster 201 is within the normal operating voltage range, but also realize the power balance of the battery packs, wherein the first time period and the first voltage threshold can be Design according to actual needs.

Fig. 7 is a schematic diagram of the working principle of the energy storage system 200 provided by the embodiment of the present application. When N is 8, that is, when the battery cluster 201 includes 8 battery packs, the battery cluster 201 is divided into 8 battery groups. Each battery pack includes one battery pack, and each battery pack is connected in series with a first switch _S1 and in parallel with a second switch _S2 . When the voltage on the grid side is within the normal operating range, the first controller 202 In turn, each PACK is bypassed in the first time period, specifically including: the first cycle, starting from battery PACK ₁ , first disconnecting S ₁ , turning on S ₂ , bypassing PACK ₁ , and switching on PACK ₂ ~ PACK _n is charging and discharging; in the second cycle, S ₁ of PACK ₂ is turned off, S ₂ is turned on, S ₁ of PACK 1 is turned on, S ₂ is turned off, and PACK _{1 and} PACK ₃ ~ PACKn are charged and discharged; switch in turn , in the last cycle, S ₁ of PACK _n is turned off, S ₂ is turned on, S ₁ of other PACKs is turned on, S ₂ is turned off, and PACK ₁ ~ PACK _n-1 are charged and discharged.

When the voltage at the second end of the DC/AC conversion circuit 203 is high, the number of series connections of PACKs can be increased to ensure sufficient voltage. When the grid voltage is normal, the number of series connections of PACKs can be reduced to ensure the voltage difference on both sides of the DC/AC conversion circuit 203 Small enough to improve overall system efficiency.

As the service life increases, the state of health (SOH) of the battery continues to decline, and the capacity that can be stored in the battery also decreases year by year. Due to the individual differences of batteries, the dispersion of the health of different batteries is also increasingly significant. As shown in Figure 8, the battery health of battery 1 and battery 2 gradually declines with the service life of the battery. The SOH of battery 1 is 70%, the SOH of battery 2 is 60%, and the battery health of battery 1 and battery 2 differs by 10%. The series connection of battery packs makes the charging and discharging time of each battery pack in the same battery cluster 201 the same, but the differences between battery packs are getting bigger and bigger. In order to ensure the safety and availability of any battery pack in a single cluster of batteries, the bottleneck must be considered Due to the limitation of the battery pack, the entire cluster of batteries is derated, resulting in waste of batteries. Due to differences in battery internal resistance and battery port voltage, simple parallel connection of battery clusters 201 will result in inconsistent charging and discharging among different battery clusters 201 , thus limiting battery utilization.

In some examples, when the difference between the output voltage of the battery cluster 201 and the voltage peak value of the second terminal of the DC/AC conversion circuit 203 is greater than the first voltage threshold and the remaining power difference of the N battery packs is greater than or equal to the first power threshold When , the first controller 202 is used to control the bypass time of battery packs with different remaining power to be different so that the difference between the remaining power of the N battery packs is less than the first power threshold, which specifically includes: when any battery in the N battery packs When the remaining power of the pack is greater than the average value of the remaining power of the N battery packs, the bypass time of the battery pack is reduced, wherein the bypass time of the battery pack is the time when the first switch corresponding to the battery pack is turned off and the second switch is closed. When the remaining power of any one of the N battery packs is less than the average value of the remaining power of the N battery packs, extend the bypass time of the battery pack. In this technical solution, when the difference between the output voltage of the battery cluster 201 and the peak voltage of the second terminal of the DC/AC conversion circuit 203 is greater than the first voltage threshold, it means that the output voltage of the battery cluster 201 can meet the voltage of the grid side. requirements, there is no need to connect all the battery packs in the battery cluster 201 in series, but when the difference between the remaining power of the battery packs is greater than the first power threshold, it indicates that there is a problem of unbalanced power between the battery packs. At this time, it can be controlled by The bypass time of battery packs with different capacities is different to achieve power balance between battery packs. For example, as shown in Figure 4, when the remaining power of PACK ₁ is high, its on-time can be increased by reducing its bypass time; when the remaining power of PACK ₂ is low, its bypass time can be extended to Reduce its conduction time, so that the remaining power among the various PACKs can be balanced. Wherein, the first power threshold can be designed according to actual requirements.

In some examples, the energy storage system 200 includes a plurality of battery clusters 201, and when the remaining power difference of the multiple battery clusters 201 is greater than or equal to a second power threshold, the first controller 202 is used to control the batteries in the multiple battery clusters 201 The number of packs connected in series makes the remaining power difference of multiple battery clusters 201 smaller than the second power threshold. The number of battery packs connected in series in each battery cluster 201 is controlled according to the result of the difference between the remaining power levels of the battery clusters 201 , so as to achieve power balance among the battery clusters 201 . Wherein, the second power threshold can be designed according to actual needs.

In some examples, when the battery cluster 201 is in the charging state and the remaining power of any one of the N battery packs is greater than or equal to the third power threshold, the first controller 202 is used to control the battery with the remaining power greater than or equal to the third power threshold. Packet bypass.

In some examples, when the battery cluster 201 is in a discharging state and the remaining power of any one of the N battery packs is less than or equal to the fourth power threshold, the first controller 202 is used to control the battery pack whose remaining power is less than the fourth power threshold bypass.

It should be noted that the third power threshold and the fourth power threshold may be determined according to the SOC and SOH of the battery pack, or may be determined according to the voltage of the battery pack. Bypass processing includes disconnecting the current path of the battery pack corresponding to the first switch and the second switch and ensuring the connection of the current path of the energy storage system 200. Those skilled in the art can select and design the third power threshold and the fourth power threshold according to actual needs. the size of.

In the above embodiment, during the charging or discharging process of the energy storage system 200, the corresponding battery pack is controlled to set the battery pack whose remaining power is greater than the third power threshold when charging or the battery pack whose remaining power is less than the fourth power threshold when discharging. Perform bypass processing, other battery packs continue to charge or discharge, and finally all battery packs reach the same value, when the energy storage system 200 charges or discharges again, due to the balance of battery power, the time to complete charging or discharging is basically the same, which can be The energy storage system 200 has a relatively long backup time, and the utilization rate and availability of the remaining power of the energy storage system 200 are improved.

Further, after bypassing the battery pack with too much remaining power during charging or bypassing the battery pack with too little remaining power during discharging, other battery packs in the energy storage system 200 can still be charged or discharged at the maximum current without Affected by the bypass battery pack, the problem of limited power can be solved, so that the output voltage of the battery cluster 201 is within the normal operating voltage range, so that the voltage difference between the two sides of the DC/AC conversion circuit 203 is small, and the entire storage capacity is improved. The utilization and work efficiency of energy system 200.

In some examples, when the voltage at the second terminal of the DC/AC conversion circuit 203 has a transient overvoltage, the first controller 202 is used to control the number of battery packs connected in series to increase so that the output voltage of the battery pack 201 is greater than DC/AC The voltage of the second terminal of the AC conversion circuit 203 .

Exemplarily, in a specific implementation, a transient overvoltage occurs because a fault or disturbance of the power grid may cause the voltage to rise rapidly and exceed the normal voltage peak value of the second terminal of the DC/AC conversion circuit 203 . If the rapidly increased voltage is within a preset ratio compared with the peak voltage of the second terminal of the DC/AC conversion circuit 203, and the energy storage system 200 can still work within a preset time period, this situation can be called For high voltage ride through. The preset ratio can be, for example, 25% or 30% and so on. The preset duration may be, for example, 1 minute or 2 minutes. The embodiment of the present application does not limit the values of the preset ratio and the preset duration.

Exemplarily, in a specific implementation, the first controller 202 judges in real time whether the voltage at the second end of the DC/AC conversion circuit 203 has a transient overvoltage based on the detected voltage at the second end of the DC/AC conversion circuit 203. After a controller 202 obtains the voltage of the second terminal of the DC/AC conversion circuit 203, it can determine whether the voltage of the second terminal of the DC/AC conversion circuit 203 has a transient overvoltage. For example, the voltage at the second end of the DC/AC conversion circuit 203 can be compared with the pre-stored peak voltage of the second end of the DC/AC conversion circuit 203, if the voltage at the second end of the DC/AC conversion circuit 203 is greater than the pre-stored If the voltage peak value of the second terminal of the DC/AC conversion circuit 203 is determined, it is determined that the voltage of the second terminal of the DC/AC conversion circuit 203 has a transient overvoltage. If there is no transient overvoltage, keep the original working mode. If a transient overvoltage occurs, the first controller 202 controls the number of battery packs connected in series to increase, so that the output voltage of the battery pack 201 is greater than the maximum voltage of the transient overvoltage.

In some examples, the schematic diagrams of the effects of the boost working mode under the condition of transient overvoltage can be referred to FIG. 9 and FIG. 10 . In FIG. 9, state 1 is the state before the transient overvoltage occurs. In this state, the voltage V _bus of the first end of the DC/AC conversion circuit 203 can be made greater than the DC/AC conversion by increasing the number of battery packs connected in series. The peak value V _{ac_max} of the voltage V _ac at the second terminal of the circuit 203 . In FIG. 10, a transient overvoltage begins to appear at point A. Then, the first controller 202 controls the number of battery packs connected in series to increase, so that the output voltage of the battery cluster 201 is greater than the maximum voltage after the transient overvoltage occurs. Refer to state 2. After the output voltage of the battery cluster 201 is input to the DC/AC conversion circuit 203, the DC/AC conversion circuit 203 can work normally.

In the above example, when the voltage at the second end of the DC/AC conversion circuit 203 has a transient overvoltage, by rapidly increasing the number of battery packs in series in the battery cluster 201, the second end of the DC/AC conversion circuit 203 is avoided. While the voltage feeds back energy to the energy storage unit, it also makes it possible to increase the output voltage of the battery cluster 201 by increasing the number of battery packs connected in series. And output the boosted voltage to the DC/AC conversion circuit 203 so that it can work normally. That is to say, in this embodiment, the output voltage of the battery cluster 201 is increased by controlling the number of battery packs connected in series to achieve high voltage ride through, that is, the energy storage system 200 can still maintain normal operation and output power under the condition of transient overvoltage. Meet the compliance of abnormal fluctuations of the power grid without going out of the grid.

In some examples, the energy storage system 200 includes N second controllers, and the N second controllers correspond to the N battery packs one by one, that is, each battery pack includes a second controller, and the second controller is used to obtain Corresponding to the voltage and remaining power of the battery pack; the second controller is also used to control the opening and closing of the first switch and the second switch in the corresponding battery pack according to the instruction of the first controller 202 to control the number of battery packs connected in series. Including: the second controller communicates with the first controller 202, the first controller 202 can be a cluster-level control system CCU, the second controller can be a battery pack-level control system BCU, and the first controller 202 obtains the battery cluster 201 The output voltage of the battery cluster 201 is compared with the voltage of the second terminal of the DC/AC conversion circuit 203, and the output voltage of the battery cluster 201 is compared with the voltage of the second terminal of the DC/AC conversion circuit 203, thereby controlling the number of series connection of battery packs in the battery cluster 201 , and control the series connection between the battery pack and other battery packs in the same battery pack according to the remaining power of the battery pack. When the first controller 202 judges that PACK ₁ needs to be bypassed, it will download the power to the second controller inside PACK ₁ . When the second controller inside PACK ₁ receives the instruction from the first controller 202, it will control the first switch inside PACK ₁ to open and the second switch to close to bypass PACK ₁ . By monitoring the state of the correspondingly connected battery pack through the second controller, the detected data of the remaining power of the correspondingly connected battery pack is more accurate, and the control of the correspondingly connected first switch and the second switch is also more accurate. Wherein, the second controller may be located inside each battery pack or outside each battery pack, which is not limited in this embodiment of the present application.

The embodiment of the present application does not specifically limit the communication method between the first controller 202 and the second controller. The communication method includes wired and wireless communication methods. The first controller 202 and the second controller can communicate based on the RS-485 bus. Or communicate based on a CAN (Controller Area Network, local area network) protocol. In other embodiments, communication may also be performed based on other communication methods, which are not limited in this application.

In some examples, the energy storage system 200 includes a voltage detection circuit; the voltage detection circuit is used to detect the voltage of the battery cluster 201 and the voltage of the second terminal of the DC/AC conversion circuit 203; the voltage detection circuit is used to output the detected voltage to the first A controller 202 .

In some examples, the energy storage system 200 includes a fault detection circuit; the fault detection circuit is used to detect a fault of the battery pack, and instructs the first controller 202 to control the first switch of the faulty battery pack to be turned off after the fault is detected. The second switch is closed. In this way, the faulty battery pack can be bypassed, reducing the impact of the fault from spreading to other battery packs, and reducing other risks caused by the fault. Among them, the faults of the battery pack include short circuit faults, communication faults, electrolyte leakage, thermal runaway and other faults. The application does not limit the specific types of faults, and those skilled in the art can set them according to actual needs.

The embodiment of the present application also provides an energy storage device. The energy storage device includes a battery pack, a first switch, a second switch, and a second controller. The battery pack includes a plurality of battery cells connected in series or in parallel. The battery pack and The first switch is connected in series, and the battery pack in series and the first switch are connected in parallel with the second switch; the second controller is used to control the closing or opening of the first switch and the second switch to control the energy storage device to be connected in series with other energy storage devices or Bypass; when the first switch is closed and the second switch is open, the energy storage device is connected in series with other energy storage devices; when the first switch is open and the second switch is closed, the energy storage device is bypassed.

In combination with the second aspect, in a possible implementation manner, the energy storage device is used to be connected in series with multiple other energy storage devices, all the energy storage devices are used to connect to the first end of the DC/AC conversion circuit, and the DC/AC conversion circuit The second terminal is used to connect the grid-connected point, and the DC/AC conversion circuit is used to connect the grid or load through the grid-connected point; the second controller is used to detect that the total output voltage of all energy storage devices is less than or equal to the first DC/AC conversion circuit When there is a peak voltage at the two terminals, the first switch in the energy storage device is controlled to be closed, and the second switch is turned off, so that the energy storage device and other energy storage devices are connected in series, so that the total output voltage of all energy storage devices is greater than the DC/AC conversion The peak voltage at the second terminal of the circuit.

The present application also provides an energy storage management system. The energy storage management system includes a DC/AC conversion circuit 203 and a first controller 202; The second end is used to connect the grid-connected point 300, and the DC/AC conversion circuit 203 is used to connect the grid or load 500 through the grid-connected point 300; the battery cluster 201 includes N battery packs, and the N battery packs are connected in series; the first controller 202 Used to obtain the voltage of the second terminal of the battery cluster 201 and the DC/AC conversion circuit 203 , and to control the number of battery packs connected in series so that the output voltage of the battery cluster 201 is greater than the peak voltage of the second terminal of the DC/AC conversion circuit 203 .

In some examples, the battery cluster 201 includes N first switches and N second switches, and the N first switches and N second switches correspond to the battery packs one by one, and each battery pack is connected in series with a first switch, and the series connected Each battery pack and the first switch are connected in parallel with a second switch; the first controller 202 is used to control the closing or opening of the first switch and the second switch corresponding to each battery pack to control the connection between the battery pack and other batteries in the same battery cluster. The series connection of battery packs or the bypass of battery packs, when the first switch is closed and the second switch is open, the battery packs corresponding to the first switch and the second switch are connected in series with other battery packs; when the first switch is open, the second switch When the second switch is closed, the battery pack corresponding to the first switch and the second switch is bypassed.

For the specific implementation and working principles of the above-mentioned energy storage device and energy storage management system, reference may be made to the relevant descriptions of the energy storage system described in FIGS.

In this application, the terms "first" and "second" are used to distinguish the same or similar items with basically the same function and function. It should be understood that "first", "second" and "Nth" There are no logical or timing dependencies, nor are there restrictions on quantity or order of execution. It should also be understood that although the following description uses the terms first, second, etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the application. scope.

Claims (15)

1. An energy storage system, comprising at least one battery cluster and a first controller, a DC/AC conversion circuit;

the battery cluster is connected with a first end of the DC/AC conversion circuit, a second end of the DC/AC conversion circuit is used for being connected with a grid connection point, and the DC/AC conversion circuit is connected with a power grid or a load through the grid connection point;

the battery cluster comprises N battery packs which are connected in series, wherein N is an integer greater than or equal to 2;

the first controller is used for controlling the serial number of the battery packs so that the output voltage of the battery cluster is larger than the voltage peak value of the second end of the DC/AC conversion circuit.

2. The energy storage system of claim 1, comprising N first switches and N second switches, the N first switches and the N second switches being in one-to-one correspondence with the N battery packs, each of the N battery packs being in series with one of the N first switches, the each battery pack and the first switch in series being in parallel with one of the N second switches;

the first controller is used for controlling the first switch and the second switch corresponding to each battery pack to be closed or opened so as to control the battery pack to be connected in series with other battery packs in the same battery cluster or bypass the battery packs;

when the first switch is closed and the second switch is opened, the battery packs corresponding to the first switch and the second switch are connected in series with other battery packs in the same battery cluster;

when the first switch is opened and the second switch is closed, the battery packs corresponding to the first switch and the second switch are bypassed.

3. The energy storage system of claim 2, wherein when the difference between the output voltage of the battery cluster and the voltage peak at the second end of the DC/AC conversion circuit is greater than or equal to a first voltage threshold, the first controller is configured to sequentially control each battery pack bypass during a first period of time, the first controller is configured to control the corresponding first switches of all battery packs in the battery pack that need to be bypassed to be open, and the second switch to be closed, wherein each battery pack includes one or more of the battery packs;

The first controller is further configured to control the first switch corresponding to other battery packs in the battery cluster that are not bypassed to be closed, and the second switch to be opened, where the other battery packs in the battery cluster that are not bypassed realize charging and discharging of the battery cluster through the DC/AC conversion circuit.

4. The energy storage system according to claim 2 or 3, wherein when a difference between the output voltage of the battery cluster and the voltage peak value of the second terminal of the DC/AC conversion circuit is greater than a first voltage threshold and a difference between the remaining power of the N battery packs is greater than or equal to a first power threshold, the first controller is configured to control bypass times of the battery packs having different remaining powers to be different so that the difference between the remaining power of the N battery packs is less than the first power threshold, comprising:

when the residual electric quantity of any one of the N battery packs is larger than the average value of the residual electric quantities of the N battery packs, reducing the bypass time of the battery packs;

and when the residual electric quantity of any one of the N battery packs is smaller than the average value of the residual electric quantities of the N battery packs, prolonging the bypass time of the battery packs.

5. The energy storage system according to any one of claims 2 to 4, wherein the energy storage system comprises N second controllers, the N second controllers are in one-to-one correspondence with the N battery packs, and the second controllers are used for obtaining voltages and remaining amounts of electricity corresponding to the battery packs;

The second controller is also used for controlling the opening and closing of the first switch and the second switch corresponding to the battery pack according to the instruction of the first controller so as to control the serial number of the battery packs.

6. The energy storage system of any of claims 1-5, wherein the energy storage system comprises a plurality of battery clusters, and the first controller is configured to control the number of series-connected battery packs in the plurality of battery clusters such that the difference in the remaining power of the plurality of battery clusters is less than a second power threshold when the difference in the remaining power of the plurality of battery clusters is greater than or equal to the second power threshold.

7. The energy storage system of claim 6, wherein the first controller is configured to control the battery pack bypass to have a remaining charge greater than or equal to a third charge threshold when the plurality of battery clusters are in a charged state and the remaining charge of any one of the N battery packs is greater than or equal to the third charge threshold.

8. The energy storage system of claim 7, wherein the first controller is configured to control the battery pack bypass to have a remaining charge of a fourth charge threshold or less when the plurality of battery clusters are in a discharged state and the remaining charge of any one of the N battery packs is less than or equal to the fourth charge threshold.

9. The energy storage system of any of claims 1-8, wherein the energy storage system comprises a plurality of DC/AC conversion circuits, each of the battery clusters being connected to a first end of the DC/AC conversion circuit, a second end of the plurality of DC/AC conversion circuits each being coupled to an AC bus, the AC bus connecting the grid-tie points.

10. The energy storage system according to any one of claims 2 to 9, wherein the first controller is configured to control the first switches corresponding to the N battery packs to be closed and the second switches to be opened in the event of a transient overvoltage in the voltage at the second end of the DC/AC conversion circuit, so that the N battery packs are connected in series.

11. The energy storage system of any of claims 1-10, wherein the energy storage system comprises a fault detection circuit; the fault detection circuit is used for detecting the fault of any one of the N battery packs, and after the fault of the battery pack is detected, the first controller is instructed to control the first switch of the battery pack with the fault to be opened, and the second switch is closed.

12. An energy storage device, comprising a battery pack, a first switch, a second switch and a second controller, wherein the battery pack comprises a plurality of electric cores, the battery pack is connected in series with the first switch, and the battery pack and the first switch which are connected in series are connected in parallel with the second switch;

The second controller is used for controlling the first switch and the second switch to be closed or opened so as to control the energy storage device to be connected in series with other energy storage devices or bypass the energy storage device;

when the first switch is closed and the second switch is opened, the energy storage device is connected with other energy storage devices in series;

when the first switch is open and the second switch is closed, the energy storage device is bypassed.

13. The energy storage device of claim 12, wherein the energy storage device is configured to be connected in series with a plurality of other energy storage devices, the energy storage device and the plurality of other energy storage devices being connected in series to form an energy storage unit, the energy storage unit being configured to be connected to a first end of a DC/AC conversion circuit, a second end of the DC/AC conversion circuit being configured to be connected to a grid connection point, the DC/AC conversion circuit being configured to be connected to a grid or a load through the grid connection point;

the second controller is used for controlling the first switch in the energy storage device to be closed and controlling the second switch to be opened when the output voltage of the energy storage unit is detected to be smaller than or equal to the voltage peak value of the second end of the DC/AC conversion circuit, so that the energy storage device and other energy storage devices are connected in series, and the output voltage of the energy storage unit is larger than the voltage peak value of the second end of the DC/AC conversion circuit.

14. The energy storage management system is characterized by comprising a DC/AC conversion circuit and a first controller, wherein a first end of the DC/AC conversion circuit is connected with a battery cluster, a second end of the DC/AC conversion circuit is used for being connected with a grid connection point, and the DC/AC conversion circuit is connected with a power grid or a load through the grid connection point;

the battery cluster comprises N battery packs, wherein the N battery packs are connected in series;

the first controller is used for controlling the serial number of the battery packs so that the output voltage of the battery cluster is larger than the voltage peak value of the second end of the DC/AC conversion circuit.

15. The energy storage management system of claim 14, wherein the battery cluster comprises N first switches and N second switches, the N first switches and the N second switches being in one-to-one correspondence with the N battery packs, each of the N battery packs being in series with one of the N first switches, the each battery pack and the first switch in series being in parallel with one of the N second switches;

the first controller is used for controlling the first switch and the second switch corresponding to each battery pack to be closed or opened so as to realize the serial connection of the battery pack and other battery packs in the same battery cluster or bypass the battery packs;

When the first switch is closed and the second switch is opened, the battery packs corresponding to the first switch and the second switch are connected in series with other battery packs in the same battery cluster;

and when the first switch is disconnected and the second switch is closed, the battery pack corresponding to the first switch and the second switch bypasses.