Charging and discharging control method of energy storage system and energy storage system

Abstract

The invention discloses an energy storage system charging and discharging control method and an energy storage system. The storage system comprises a first battery pack and a second battery pack; the first battery pack and the second battery pack are connected through a parallel operation cable; the method comprises the following steps: acquiring the voltage and residual electric quantity of a first battery pack and the voltage and residual electric quantity of a second battery pack in real time; when it is determined that the first battery pack and the second battery pack meet parallel operation conditions according to the voltage and the remaining capacity of the first battery pack and the voltage and the remaining capacity of the second battery pack, the first battery pack and the second battery pack are controlled to be subjected to parallel operation; after the first battery pack and the second battery pack are subjected to parallel operation, a parallel operation target signal is obtained; and according to the current voltage of the first battery pack, the current voltage of the second battery pack and the parallel operation target signal, determining a charging and discharging signal of the first battery pack and a charging and discharging signal of the second battery pack. According to the scheme, the circulating current problem after parallel operation of the first battery pack and the second battery pack is solved, and meanwhile, the charging and discharging requirements of the energy storage system after parallel operation are met.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of battery packs, and in particular, to a charge-discharge control method for an energy storage system and an energy storage system. Background Art

[0002] With the wide application of portable energy storage systems in fields such as outdoor activities, emergency rescue, and mobile power supply, in order to meet the requirements of high-power application scenarios, the first battery pack and the second battery pack often achieve energy sharing and capacity expansion through parallel operation;

[0003] However, during the process of energy sharing and capacity expansion after the parallel operation of the first battery pack and the second battery pack, the voltage difference between the first battery pack and the second battery pack often causes a circulating current phenomenon, and the surge circulating current may damage the circuit structure of each battery pack, causing abnormal operation of each battery pack, which poses a threat to the safety and stability of the entire system composed of the first battery pack and the second battery pack. Therefore, studying and solving the abnormal circulating current problem that occurs after the parallel operation of the first battery pack and the second battery pack is of great significance for improving the reliability of the entire system and the user experience. Summary of the Invention

[0004] The present invention provides a charge-discharge control method for an energy storage system and an energy storage system to solve the circulating current problem after the parallel operation of the first battery pack and the second battery pack, and at the same time meet the charge-discharge requirements of the energy storage system after parallel operation.

[0005] To achieve the above object, in a first aspect, the embodiments of the present invention provide a charge-discharge control method for an energy storage system, where the energy storage system includes a first battery pack and a second battery pack; the first battery pack and the second battery pack are connected through a parallel operation cable; the method includes:

[0006] Obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack in real time;

[0007] When it is determined that the first battery pack and the second battery pack meet the parallel operation conditions according to the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to perform parallel operation;

[0008] After the first battery pack and the second battery pack are in parallel operation, obtain a parallel operation target signal;

[0009] Determine the charge-discharge signals of the first battery pack and the charge-discharge signals of the second battery pack according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel operation target signal.

[0010] Optionally, the parallel operation target signal includes a discharge target power;

[0011] Determine the charge-discharge signals of the first battery pack and the second battery pack according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel operation target signal, including:

[0012] Determine the output power distribution ratio between the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack;

[0013] Determine the output power of the first battery pack and the output power of the second battery pack respectively according to the output power distribution ratio and the discharge target power.

[0014] Optionally, determining the output power distribution ratio between the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack includes:

[0015] Determine the difference range to which the voltage difference belongs according to the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack;

[0016] Determine the output power distribution ratio between the first battery pack and the second battery pack according to the difference range to which the voltage difference belongs.

[0017] Optionally, when the voltage difference is greater than or equal to 0, the output power distribution ratio is greater than or equal to 1; when the voltage difference is less than 0, the output power distribution ratio is less than 1;

[0018] Optionally, different difference ranges correspond to different output power distribution ratios.

[0019] Optionally, determining the output power distribution ratio between the first battery pack and the second battery pack according to the difference range to which the voltage difference belongs includes:

[0020] When the difference range to which the voltage difference belongs is the first difference range, determine that the output power distribution ratio between the first battery pack and the second battery pack is the first ratio;

[0021] When the difference range to which the voltage difference belongs is the second difference range, determine that the output power distribution ratio between the first battery pack and the second battery pack is the second ratio;

[0022] Wherein, the lower limit value of the first difference range is greater than or equal to the upper limit value of the second difference range, and the first ratio is greater than the second ratio.

[0023] Optionally, the parallel operation target signal includes the total charging current;

[0024] Determining the charge and discharge signals of the first battery pack and the second battery pack according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel operation target signal, includes:

[0025] Determining the charging current distribution ratio of the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack;

[0026] Determining the charging current of the first battery pack and the charging current of the second battery pack respectively according to the total charging current and the charging current distribution ratio.

[0027] Optionally, determining the charging current distribution ratio of the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack, includes:

[0028] Determining the first charging current ratio of the first battery pack according to the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack;

[0029] Determining the second charging current ratio of the second battery pack according to the first charging current ratio; wherein, the sum of the first charging current ratio and the second charging current ratio is less than or equal to 1.

[0030] Optionally, determining the first charging current ratio of the first battery pack according to the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack, includes:

[0031] Constructing a charging current distribution ratio model; wherein, the charging current factor distribution model is an increasing function;

[0032] Substituting the difference between the current voltage of the first battery pack and the current voltage of the second battery pack into the charging current distribution ratio model to calculate the first charging current ratio of the first battery pack.

[0033] Optionally, the parallel operation condition includes that the initial difference between the initial voltage of the first battery pack and the initial voltage of the second battery pack is less than a preset voltage threshold, and the initial difference between the initial remaining power of the first battery pack and the initial remaining power of the second battery pack is less than a preset power threshold.

[0034] Optionally, before controlling the first battery pack and the second battery pack to perform parallel operation, it further includes:

[0035] Judging whether the first battery pack and the second battery pack meet the parallel operation condition according to the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack;

[0036] If not, adjust the initial voltage of the first battery pack and the initial voltage of the second battery pack to the target voltage.

[0037] Optionally, adjusting the initial voltage of the first battery pack and the initial voltage of the second battery pack to the target voltage includes:

[0038] Adjust the initial voltage of the first battery pack and the initial voltage of the second battery pack at a preset voltage adjustment rate until the initial voltage of the first battery pack and the initial voltage of the second battery pack are both the target voltage.

[0039] In a second aspect, an embodiment of the present invention further provides an energy storage system, which includes: a first battery pack, a second battery pack, and a control module; the first battery pack and the second battery pack are electrically connected through a parallel connection cable;

[0040] The first battery pack at least includes a first battery pack body, and the second battery pack at least includes a second battery pack body; the control module is respectively connected to the first battery pack body and the second battery pack body; the control module is used to execute the energy storage system charge and discharge control method described in the first aspect.

[0041] Optionally, the first battery pack further includes a first charge and discharge circuit and a first DC / DC unit; the second battery pack further includes a second charge and discharge circuit and a second DC / DC unit;

[0042] The first battery pack body is connected to the first DC / DC unit through the first charge and discharge circuit; the second battery pack body is connected to the second DC / DC unit through the second charge and discharge circuit;

[0043] Both the first DC / DC unit and the second DC / DC unit are electrically connected to the parallel connection cable;

[0044] The first DC / DC unit is used to detect the voltage and remaining capacity of the first battery pack in real time;

[0045] The second DC / DC unit is used to detect the voltage and remaining capacity of the second battery pack in real time.

[0046] Optionally, the first DC / DC unit includes a first voltage detection sub-unit, a first DC / DC chip, and a first controller;

[0047] The first voltage detection sub-unit is connected to the first battery pack body and is used to detect the voltage and remaining power of the first battery pack body in real time;

[0048] The first controller is respectively connected to the first voltage detection subunit and the first DC / DC chip, and is configured to control the operating states of the first DC / DC chip and the first charge and discharge circuit at least according to the voltage and remaining power of the first battery pack body.

[0049] Optionally, the second DC / DC unit includes a second voltage detection subunit, a second DC / DC chip, and a second controller;

[0050] The second voltage detection subunit is connected to the second battery pack body and is configured to detect the voltage and remaining power of the second battery pack body in real time;

[0051] The second controller is respectively connected to the second voltage detection subunit and the second DC / DC chip, and is configured to control the operating states of the second DC / DC chip and the second charge and discharge circuit at least according to the voltage and remaining power of the second battery pack body.

[0052] Optionally, the control module is integrated in the first DC / DC unit or the second DC / DC unit.

[0053] In an embodiment of the present invention, after the first battery pack and the second battery pack are paralleled, a paralleling target signal is obtained; according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the paralleling target signal, the charge and discharge signals of the first battery pack and the charge and discharge signals of the second battery pack are determined. In this way, after paralleling, the first battery pack charges and discharges according to the charge and discharge signals, and the second battery pack charges and discharges according to the charge and discharge signals. While meeting the charge and discharge requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, the circulating current problem caused by too large a voltage deviation between the first battery pack and the second battery pack after paralleling is also avoided.

[0054] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0056] Figure 1 is a flowchart of a method for controlling charge and discharge of an energy storage system provided by an embodiment of the present invention;

[0057] Figure 2 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0058] Figure 3 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0059] Figure 4 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0060] Figure 5 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0061] Figure 6 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0062] Figure 7 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0063] Figure 8 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention;

[0064] Figure 9 It is a schematic structural diagram of an energy storage system provided by an embodiment of the present invention;

[0065] Figure 10 It is a specific schematic structural diagram of an energy storage system provided by an embodiment of the present invention;

[0066] Figure 11 It is a specific schematic structural diagram of another energy storage system provided by an embodiment of the present invention;

[0067] Figure 12 It is a specific schematic structural diagram of another energy storage system provided by an embodiment of the present invention. Detailed implementation manners

[0068] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0069] It should be noted that the terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data used can be interchanged under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0070] Figure 1 is a flowchart of a charge and discharge control method for an energy storage system provided by an embodiment of the present invention; the energy storage system includes a first battery pack and a second battery pack; this embodiment is applicable to the case where the first battery pack and the second battery pack are paralleled through a parallel cable and jointly perform charge and discharge. This method can be executed by software or hardware, such as Figure 1 As shown, the charge and discharge control method for this energy storage system specifically includes the following steps:

[0071] S110. Real-time obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack.

[0072] Among them, the voltage of the first battery pack is the real-time voltage value of the first battery pack before and after paralleling; generally, the voltage value of the first battery pack before paralleling can be a fixed open-circuit voltage; the voltage value of the first battery pack after paralleling will change in real time as the charge and discharge process progresses; the remaining power SOC of the first battery pack is the remaining power SOC of the first battery pack before paralleling; generally, the remaining power SOC of the first battery pack before paralleling can be a fixed remaining power SOC;

[0073] The voltage of the second battery pack is the real-time voltage value of the second battery pack before and after paralleling; generally, the voltage value of the second battery pack before paralleling can be a fixed open-circuit voltage; the voltage value of the second battery pack after paralleling will change in real time as the charge and discharge process progresses; the remaining power SOC of the second battery pack is the remaining power SOC of the second battery pack before paralleling; generally, the remaining power SOC of the second battery pack before paralleling can be a fixed remaining power SOC.

[0074] S120. When it is determined that the first battery pack and the second battery pack meet the paralleling condition according to the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to be paralleled.

[0075] Among them, when the parallel connection condition is satisfied, the voltage deviation between the first battery pack and the second battery pack is small, and the remaining power deviation between the first battery pack and the second battery pack is small; due to the small voltage deviation between the first battery pack and the second battery pack and the small remaining power deviation between the first battery pack and the second battery pack when the parallel connection condition is satisfied, a circulating current can be avoided between the first battery pack and the second battery pack during the parallel connection process, thus ensuring the stability of the subsequent charge and discharge process after parallel connection.

[0076] S130. After the first battery pack and the second battery pack are paralleled, obtain a parallel connection target signal.

[0077] Among them, the parallel connection target signal is a target demand signal for the first battery pack and the second battery pack to perform charge and discharge simultaneously after being paralleled; the parallel connection target signal can be determined according to the charging scenario when the first battery pack and the second battery pack are charging simultaneously after being paralleled, and the discharging scenario when the first battery pack and the second battery pack are discharging simultaneously after being paralleled. The parallel connection target signal can be a target current signal, or a target power signal, or a target maximum power signal, and no specific limitation is made here.

[0078] S140. Determine the charge and discharge signal of the first battery pack and the charge and discharge signal of the second battery pack according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel connection target signal.

[0079] Among them, the charge and discharge signal of the first battery pack is the actual charge and discharge working signal of the first battery pack during the common charge and discharge process of the first battery pack and the second battery pack;

[0080] The charge and discharge signal of the second battery pack is the actual charge and discharge working signal of the second battery pack during the common charge and discharge process of the first battery pack and the second battery pack; the charge and discharge signal of the first battery pack and the charge and discharge signal of the second battery pack can both be charge and discharge current signals, or charge and discharge power signals, or charge and discharge maximum power signals, and no specific limitation is made here.

[0081] As the first battery pack and the second battery pack charge and discharge after parallel connection, the voltages of the first battery pack and the second battery pack change in real time. In this embodiment, based on the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel connection target signal, the charge and discharge signals of the first battery pack and the second battery pack are determined. After the first battery pack operates according to its corresponding charge and discharge signal and the second battery pack operates according to its corresponding charge and discharge signal, the voltage of the first battery pack changes based on its current voltage, and the voltage of the second battery pack also changes based on its current voltage. The voltage deviation between the changed first battery pack and the changed second battery pack will not cause a circulating current between the first battery pack and the second battery pack; at the same time, the first battery pack operates according to its corresponding charge and discharge signal and the second battery pack operates according to its corresponding charge and discharge signal, which can meet the parallel connection target signal.

[0082] In the embodiment of the present invention, after the first battery pack and the second battery pack are connected in parallel, a parallel connection target signal is obtained; according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel connection target signal, the charge and discharge signals of the first battery pack and the second battery pack are determined. After parallel connection, the first battery pack charges and discharges according to the charge and discharge signal, and the second battery pack charges and discharges according to the charge and discharge signal. In this way, while meeting the charge and discharge requirements of the energy storage system after the first battery pack and the second battery pack are connected in parallel, the problem of circulating current caused by too large a voltage deviation between the first battery pack and the second battery pack after parallel connection is also avoided.

[0083] Optionally, based on the above embodiment, the scenario where the first battery pack and the second battery pack discharge simultaneously after parallel connection is described; Figure 2 It is a flowchart of another energy storage system charge and discharge control method provided by the embodiment of the present invention; as Figure 2 shown, when the parallel connection target signal includes a discharge target power, the energy storage system charge and discharge control method specifically includes the following steps:

[0084] S210. Real-time obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack.

[0085] S220. When it is determined that the first battery pack and the second battery pack meet the parallel connection condition according to the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to be connected in parallel.

[0086] S230. After the first battery pack and the second battery pack are connected in parallel, obtain the discharge target power.

[0087] Among them, the discharge target power is the expected discharge power value set according to the load demand during the simultaneous discharge process after the first battery pack and the second battery pack are paralleled; that is, it is also the power output value jointly achieved by the first battery pack and the second battery pack during the discharge process. By setting the discharge target power matching the load demand, over-discharge or under-discharge can be avoided, the energy utilization efficiency can be improved, and the discharge stability can be enhanced.

[0088] S240. Determine the output power distribution ratio between the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack.

[0089] Among them, the output power distribution ratio may include the first output power ratio of the first battery pack, the second output power ratio of the second battery pack, and the relative output power ratio determined by the ratio of the first output power ratio to the second output power ratio; for example: the output power distribution ratio is 80%:20%, so the first output power ratio is 80%, and the second output power ratio is 20%; the relative output power ratio is 80% / 20%.

[0090] Determine the output power distribution ratio between the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack. After the first battery pack and the second battery pack perform power distribution according to the output power distribution ratio between the first battery pack and the second battery pack, the current voltages of the subsequent first battery pack and the second battery pack will decrease at different ratios.

[0091] S250. Determine the output power of the first battery pack and the output power of the second battery pack respectively according to the output power distribution ratio and the discharge target power.

[0092] Specifically, the output power of the first battery pack can be determined according to the first output power ratio in the output power distribution ratio and the discharge target power; the output power of the second battery pack can be determined according to the second output power ratio in the output power distribution ratio and the discharge target power; or the output power of the first battery pack and the output power of the second battery pack can be directly determined according to the relative output power ratio.

[0093] After the first battery pack and the second battery pack perform power output according to the output power of the first battery pack and the output power of the second battery pack, the current voltages of the first battery pack and the second battery pack will decrease at different ratios, and finally the voltage deviation between the first battery pack and the second battery pack will be relatively small, thereby avoiding the generation of circulating current between the first battery pack and the second battery pack during the discharge process while meeting the discharge target power.

[0094] In this embodiment, the first battery pack discharges according to the output power of the first battery pack, and the second battery pack discharges according to the output power of the second battery pack. While meeting the discharge requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, it also avoids the circulating current problem caused by too large a voltage deviation between the first battery pack and the second battery pack after paralleling.

[0095] Optionally, based on the above embodiment, the determination of the output power distribution ratio in step S240 is further refined. Figure 3 It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention; as Figure 3 shown, this charge and discharge control method for an energy storage system specifically includes the following steps:

[0096] S310. Obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack in real time.

[0097] S320. When it is determined that the first battery pack and the second battery pack meet the paralleling condition according to the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to be paralleled.

[0098] S330. After the first battery pack and the second battery pack are paralleled, obtain the target discharge power.

[0099] S340. Determine the difference range to which the voltage difference belongs according to the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack.

[0100] Among them, the difference range can represent the voltage difference level between the voltage of the first battery pack and the voltage of the second battery pack; the difference range includes different-level difference ranges; for example: different-level difference ranges can include a high difference range, a medium difference range, and a low difference range.

[0101] In this embodiment, the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack is specifically determined by the voltage of the first battery pack and the current voltage of the second battery pack, and the difference range is determined according to the voltage difference, so as to determine the voltage difference level between the current voltage of the first battery pack and the current voltage of the second battery pack.

[0102] S350. Determine the output power distribution ratio between the first battery pack and the second battery pack according to the difference range to which the voltage difference belongs.

[0103] Among them, according to the difference range to which the voltage difference belongs, the output power distribution ratio between the first battery pack and the second battery pack is determined, that is, the output power distribution ratio between the first battery pack and the second battery pack is determined according to the voltage difference level between the current voltage of the first battery pack and the current voltage of the second battery pack. After the first battery pack and the second battery pack perform power distribution according to the output power distribution ratio between the first battery pack and the second battery pack, the current voltage of the first battery pack and the current voltage of the second battery pack will decrease at different ratios subsequently.

[0104] It can be understood that determining the output power distribution ratio between the first battery pack and the second battery pack according to the difference range to which the voltage difference belongs includes: determining some same output power distribution ratios according to different difference ranges to which the voltage differences belong; or correspondingly determining different same output power distribution ratios.

[0105] Preferably, in some embodiments, different difference ranges correspond to different output power distribution ratios; in this way, different output power distribution ratios can be determined according to different difference ranges, so that different output power distribution ratios can be carried out at different voltage difference levels, so as to more accurately output different output power distribution ratios, ensure different discharge output power regulations at different voltage difference levels, so that the voltages of the first battery pack and the second battery pack after change tend to be consistent, the circulating current suppression is obvious, and the problem of obvious circulating current suppression caused by the same output power distribution at different voltage difference levels is avoided; for example, when the difference range is >5V; the output power distribution ratio between the first battery pack and the second battery pack is: 80%:20%; when the difference range is 3V - 5V; the output power distribution ratio between the first battery pack and the second battery pack is: 60%:40%; when the difference range is <3V; the output power distribution ratio between the first battery pack and the second battery pack is: 50%:50%.

[0106] S360. According to the output power distribution ratio and the discharge target power, determine the output power of the first battery pack and the output power of the second battery pack respectively.

[0107] In this embodiment, the output power of the first battery pack and the output power of the second battery pack are determined based on the specific output power distribution ratio. When the first battery pack discharges according to the output power of the first battery pack and the second battery pack discharges according to the output power of the second battery pack, while meeting the discharge requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, the voltage deviation between the first battery pack and the second battery pack after paralleling is also avoided, thereby avoiding the circulating current problem caused by too large voltage deviation.

[0108] Based on the above embodiments, this embodiment elaborates on the above step S350 in detail. Figure 4It is a flowchart of another charge and discharge control method for an energy storage system provided by an embodiment of the present invention; as Figure 4 shown, the charge and discharge control method for the energy storage system specifically includes the following steps:

[0109] S410. Obtain the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack in real time.

[0110] S420. When it is determined that the first battery pack and the second battery pack meet the parallel operation conditions according to the voltage and remaining power of the first battery pack, the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to perform parallel operation.

[0111] S430. After the first battery pack and the second battery pack are in parallel operation, obtain the discharge target power.

[0112] S440. Determine the difference range to which the voltage difference belongs according to the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack.

[0113] S450. Determine the output power distribution ratio between the first battery pack and the second battery pack according to the difference range to which the voltage difference belongs; wherein, when the voltage difference is greater than or equal to 0, the output power distribution ratio is greater than or equal to 1; when the voltage difference is less than 0, the output power distribution ratio is less than 1.

[0114] Considering that either the first battery pack or the second battery pack can be used as the high-voltage pack, the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack can be greater than or equal to 0 or less than 0; in this embodiment, when the voltage difference is greater than or equal to 0, that is, the first battery pack is used as the high-voltage pack, the output power distribution ratio is greater than or equal to 1; when the voltage difference is less than 0, that is, the second battery pack is used as the high-voltage pack, the output power distribution ratio is greater than or equal to 1; in this way, the output power ratio of the high-voltage pack is larger and the output power ratio of the low-voltage pack is smaller, so that the high-voltage pack discharges as fast as possible and the low-voltage pack discharges more slowly, making the current voltage of the high-voltage pack drop faster and the current voltage of the low-voltage pack drop slower, thus ensuring the voltage balance between the high-voltage pack and the low-voltage pack and avoiding the generation of circulating current.

[0115] Optionally, in some embodiments, determining the output power distribution ratio between the first battery pack and the second battery pack according to the difference range to which the voltage difference belongs includes:

[0116] When the difference range to which the voltage difference belongs is the first difference range, determine the output power distribution ratio (the output power distribution ratio includes the relative output power ratio) between the first battery pack and the second battery pack as the first ratio;

[0117] When the difference range to which the voltage difference belongs is the second difference range, determine that the output power distribution ratio (including the relative output power ratio) of the first battery pack and the second battery pack is the second ratio;

[0118] Among them, the lower limit value of the first difference range is greater than or equal to the upper limit value of the second difference range, and the first ratio is greater than the second ratio.

[0119] Among them, the lower limit value of the first difference range is greater than or equal to the upper limit value of the second difference range, that is, the voltage difference level corresponding to the first difference range is higher; the voltage difference level corresponding to the second difference range is lower; when the lower limit value of the first difference range is greater than or equal to the upper limit value of the second difference range, the first ratio is greater than the second ratio. In this way, the voltage difference level is positively correlated with the relative output power ratio, which can ensure that at a higher voltage difference level, the discharge speed of the high battery pack is faster, and the discharge speed of the low battery pack is relatively slow, avoiding the slow discharge speed of the high battery pack and the accelerated discharge speed of the low battery pack at a higher voltage difference level, resulting in a larger pressure difference between the first battery pack and the second battery pack and causing a circulating current problem.

[0120] Exemplarily, when the difference range is >5V; the output power distribution ratio of the first battery pack and the second battery pack is: 80%:20%, that is, the relative output power ratio is 4 / 1; when the difference range is 3V - 5V; the output power distribution ratio of the first battery pack and the second battery pack is: 60%:40%, that is, the relative output power ratio is 6 / 4.

[0121] S460. Determine the output power of the first battery pack and the output power of the second battery pack respectively according to the output power distribution ratio and the discharge target power.

[0122] In this embodiment, based on a more specific method for determining the output power distribution ratio, when the first battery pack discharges according to the output power of the first battery pack and the second battery pack discharges according to the output power of the second battery pack, while meeting the discharge requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, it also avoids the circulating current problem caused by too large a voltage deviation between the first battery pack and the second battery pack after paralleling.

[0123] Optionally, the following describes the scenario of simultaneous charging after the first battery pack and the second battery pack are paralleled; Figure 5 It is a flowchart of another energy storage system charge and discharge control method provided by the embodiments of the present invention; as Figure 5 shown, when the parallel target signal includes the total charging current, the energy storage system charge and discharge control method specifically includes the following steps:

[0124] S510. Real-time obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack.

[0125] S520. When it is determined that the first battery pack and the second battery pack meet the parallel operation conditions based on the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to perform parallel operation.

[0126] S530. After the first battery pack and the second battery pack are in parallel operation, obtain the total charging current.

[0127] Wherein, the total charging current is the expected charging current value set according to the charging current signal currently allowed to be output by the mains electricity during the charging process when the first battery pack and the second battery pack are in parallel operation and charging simultaneously; by setting the total charging current matching the charging current signal output by the mains electricity, overcharging can be avoided, and the charging efficiency can be effectively improved and the life of each battery pack can be protected.

[0128] S540. Determine the charging current distribution ratio of the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack;

[0129] Wherein, the charging current distribution ratio includes the first charging current ratio of the first battery pack and the second charging current ratio of the second battery pack;

[0130] Determine the charging current distribution ratio of the first battery pack and the second battery pack according to the current voltage of the first battery pack and the current voltage of the second battery pack (it can be understood that the two parameters of the current voltage of the first battery pack and the current voltage of the second battery pack can be in any relationship form, such as a difference relationship or a ratio relationship); after the first battery pack and the second battery pack perform current distribution according to the charging current distribution ratio of the first battery pack and the second battery pack, the current voltages of the subsequent first battery pack and the second battery pack will increase at different ratios.

[0131] S550. Determine the charging current of the first battery pack and the charging current of the second battery pack respectively according to the total charging current and the charging current distribution ratio.

[0132] Specifically, the charging current of the first battery pack can be determined according to the first charging current ratio of the first battery pack in the charging current distribution ratio and the total charging current; the charging current of the second battery pack can be determined according to the second charging current ratio of the second battery pack in the output power distribution ratio and the total charging current.

[0133] After the first battery pack and the second battery pack are charged according to the charging current of the first battery pack and the charging current of the second battery pack, the current voltages of the first battery pack and the second battery pack will increase at different ratios, and finally the voltage deviation between the first battery pack and the second battery pack will be small, so that while meeting the total charging current, the generation of circulating current between the first battery pack and the second battery pack during the charging process is avoided.

[0134] In this embodiment, the first battery pack is charged according to the charging current of the first battery pack, and the second battery pack is charged according to the charging current of the second battery pack. While meeting the charging requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, it also avoids the circulating current problem caused by too large a voltage deviation between the first battery pack and the second battery pack after paralleling.

[0135] Optionally, on the basis of the above embodiment, the determination of the charging current distribution ratio in step S540 is further refined. Figure 6 It is a flowchart of another charge-discharge control method for an energy storage system provided by an embodiment of the present invention; as Figure 6 shown, the charge-discharge control method for this energy storage system specifically includes the following steps:

[0136] S610. Real-time obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack.

[0137] S620. When it is determined that the first battery pack and the second battery pack meet the paralleling condition according to the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to be paralleled.

[0138] S630. After the first battery pack and the second battery pack are paralleled, obtain the total charging current.

[0139] S640. Determine the first charging current ratio of the first battery pack according to the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack.

[0140] Specifically, in this embodiment, the first charging current ratio of the first battery pack is determined by the voltage difference between the current voltage of the first battery pack and the current voltage of the second battery pack; among them, different voltage differences can correspond to different first charging current ratios of the first battery pack; different voltage differences can also correspond to some identical first charging current ratios of the first battery pack.

[0141] S650. Determine the second charging current ratio of the second battery pack according to the first charging current ratio; where the sum of the first charging current ratio and the second charging current ratio is less than or equal to 1.

[0142] Among them, when the first battery pack is in the state of the first charging current ratio, the voltage of the first battery pack continuously increases based on the current voltage of the first battery pack; when the second battery pack is in the state of the second charging current ratio, the voltage of the second battery pack continuously increases based on the current voltage of the second battery pack; this can make the voltage deviation between the first battery pack and the second battery pack smaller, thereby avoiding the occurrence of the circulating current problem.

[0143] S660. Determine the charging current of the first battery pack and the charging current of the second battery pack according to the total charging current, the first charging current ratio, and the second charging current ratio respectively.

[0144] Specifically, the charging current of the first battery pack can be determined according to the product of the first charging current ratio and the total charging current; the charging current of the second battery pack can be determined according to the product of the first charging current ratio and the total charging current.

[0145] In this embodiment, the first battery pack is charged according to the charging current of the first battery pack, and the second battery pack is charged according to the charging current of the second battery pack. While meeting the charging requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, it also avoids the circulating current problem caused by too large a voltage deviation between the first battery pack and the second battery pack after paralleling.

[0146] Based on the above embodiment, this embodiment elaborates on the above step S640. Figure 7 It is a flowchart of another method for controlling charge and discharge of an energy storage system provided by an embodiment of the present invention; as Figure 7 shown, the method for controlling charge and discharge of the energy storage system specifically includes the following steps:

[0147] S710. Real-time obtain the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack.

[0148] S720. When it is determined that the first battery pack and the second battery pack meet the paralleling condition according to the voltage and remaining power of the first battery pack, and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to be paralleled.

[0149] S730. After the first battery pack and the second battery pack are paralleled, obtain the total charging current.

[0150] S740. Construct a charging current distribution ratio model.

[0151] S750. Substitute the difference between the current voltage of the first battery pack and the current voltage of the second battery pack into the charging current distribution ratio model, and calculate the first charging current ratio of the first battery pack.

[0152] Among them, the charging current distribution ratio model is specifically:

[0153]

[0154] Among them, ΔV th is the voltage difference adjustment factor; ΔV th represents the sensitivity of the charging current ratio to the voltage difference; generally a constant and a positive number; V main is the current voltage of the first battery pack; V expis the current voltage of the second battery pack; K main is the first charging current ratio;

[0155] It can be understood that from the charging current distribution ratio model, it can be obtained that when V exp is less than V main , at this time K main is smaller, then the charging current is larger; when V exp is greater than V main , at this time K main is larger, then the charging current is smaller; that is, when the current voltage of the first battery pack is smaller, the corresponding first charging current ratio is larger. Conversely, when the current voltage of the first battery pack is larger, the corresponding first charging current ratio is smaller.

[0156] S760. Determine the second charging current ratio of the second battery pack according to the first charging current ratio; wherein, the sum of the first charging current ratio and the second charging current ratio is less than or equal to 1.

[0157] Preferably, K exp = 1 - K main ; K exp is the second charging current ratio; in this way, also referring to the above model, when V exp is less than V main , at this time K exp is larger; when V exp is greater than V main , at this time K exp is smaller, that is, when the current voltage of the second battery pack is smaller, the corresponding second charging current ratio is larger. Conversely, when the current voltage of the second battery pack is larger, the corresponding second charging current ratio is smaller.

[0158] S770. Determine the charging current of the first battery pack and the charging current of the second battery pack according to the total charging current and the first charging current ratio and the second charging current ratio respectively.

[0159] In this embodiment, based on a more specific first charging current ratio, the charging current of the first battery pack and the charging current of the second battery pack are determined. In this way, when the first battery pack is charged according to the charging current of the first battery pack and the second battery pack is charged according to the charging current of the second battery pack, while meeting the charging requirements of the energy storage system after the first battery pack and the second battery pack are paralleled, it also further precisely controls the circulating current problem caused by too large a voltage deviation between the first battery pack and the second battery pack after paralleling.

[0160] On the basis of the above embodiments, this embodiment elaborates on the paralleling conditions in the above various embodiments in detail. Figure 8 is a flowchart of another energy storage system charge and discharge control method provided by an embodiment of the present invention; as Figure 8As shown in the figure, the charge and discharge control method of the energy storage system specifically includes the following steps:

[0161] S810. Obtain the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack in real time.

[0162] S820. Determine whether the first battery pack and the second battery pack meet the parallel connection condition according to the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack; if so, execute S830; if not, execute S840;

[0163] S830. When it is determined that the first battery pack and the second battery pack meet the parallel connection condition according to the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack, control the first battery pack and the second battery pack to be connected in parallel, and execute S850 - S860;

[0164] Specifically, the parallel connection conditions include: the initial difference between the initial voltage of the first battery pack and the initial voltage of the second battery pack is less than the preset voltage threshold, and the initial difference between the initial remaining power of the first battery pack and the initial remaining power of the second battery pack is less than the preset power threshold. The preset voltage threshold is the allowable pressure difference for no circulating current between the first battery pack and the second battery pack under ideal conditions; for example: 1V; the preset power threshold is the allowable remaining power difference for no circulating current between the first battery pack and the second battery pack under ideal conditions; for example: 5%.

[0165] S840. Adjust the initial voltage of the first battery pack and the initial voltage of the second battery pack to the target voltage, and execute S850 - S860;

[0166] Among them, since each battery pack is connected to the load or the mains through the parallel connection cable after parallel connection, the target voltage can be the stable voltage on the parallel connection cable, which is beneficial for later connection to the load or the mains through the parallel connection cable. Specifically, the initial voltage of the first battery pack and the initial voltage of the second battery pack can be adjusted at a preset voltage adjustment rate until the initial voltage of the first battery pack and the initial voltage of the second battery pack are both the target voltage; in this way, the initial voltage of the first battery pack and the initial voltage of the second battery pack are both adjusted to the target voltage, so that the pressure difference between the first battery pack and the second battery pack is small during the parallel connection process, and thus no circulating current will be generated.

[0167] S850. After the first battery pack and the second battery pack are connected in parallel, obtain the parallel connection target signal.

[0168] S860. Determine the charge and discharge signals of the first battery pack and the charge and discharge signals of the second battery pack according to the current voltage of the first battery pack, the current voltage of the second battery pack, and the parallel connection target signal.

[0169] In an embodiment of the present invention, before parallel connection, it is determined whether the first battery pack and the second battery pack meet the parallel connection conditions according to the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack, thereby realizing the suppression of circulating current during the parallel connection process and improving the stability during subsequent charging and discharging processes.

[0170] Based on the same inventive concept, an embodiment of the present invention further provides an energy storage system. Figure 9 It is a schematic structural diagram of an energy storage system provided by an embodiment of the present invention; as Figure 9 shown, the energy storage system includes: a first battery pack 10, a second battery pack 20, and a control module 30; the first battery pack 10 and the second battery pack 20 are electrically connected through a parallel connection cable; the first battery pack 10 at least includes a first battery pack body 11, and the second battery pack 20 at least includes a second battery pack body 21; the control module 30 is respectively connected to the first battery pack body 11 and the second battery pack body 12; the control module 30 is used to execute the energy storage system charge and discharge control method of each of the above embodiments. It can be understood that the control module 30 can be any integrated or non-integrated form of module. Since the embodiment of the present invention includes the control module 30 that executes the energy storage system charge and discharge control method of each of the above embodiments, it also has the beneficial effects of the above embodiments, which will not be elaborated here.

[0171] Optionally, Figure 10 It is a specific structural schematic diagram of an energy storage system provided by an embodiment of the present invention. As Figure 10 shown, the first battery pack 10 further includes a first charge and discharge circuit 12 and a first DC / DC unit 13; the second battery pack 20 further includes a second charge and discharge circuit 22 and a second DC / DC unit 23; the first battery pack body 11 is connected to the first DC / DC unit 13 through the first charge and discharge circuit 12; the second battery pack body 21 is connected to the second DC / DC unit 23 through the second charge and discharge circuit 22; both the first DC / DC unit 13 and the second DC / DC unit 23 are electrically connected to the parallel connection cable; the first DC / DC unit 13 is used to detect the voltage and remaining capacity of the first battery pack 10 in real time; the second DC / DC unit 23 is used to detect the voltage and remaining capacity of the second battery pack 20 in real time.

[0172] Specifically, the control module 30 can be electrically connected or communicatively connected to the first DC / DC unit 13 and the second DC / DC unit 23 respectively, so as to be able to obtain the voltage and remaining power of the first battery pack 10 through the first DC / DC unit 13, and obtain the voltage and remaining capacity of the second battery pack 20 through the second DC / DC unit 23. When it is determined that the first battery pack 10 and the second battery pack 20 meet the parallel operation condition according to the voltage and remaining power of the first battery pack 10, and the voltage and remaining power of the second battery pack 20, the control module 30 controls the first DC / DC unit 13 and the second DC / DC unit 23 to be connected through a parallel operation cable, so that the first battery pack 10 and the second battery pack 20 complete parallel operation; after the first battery pack and the second battery pack are in parallel operation, the control module 30 obtains a parallel operation target signal, and outputs a first control instruction to the first DC / DC unit 13 and a second control instruction to the second DC / DC unit 23 according to the current voltage of the first battery pack 10, the current voltage of the second battery pack 20, and the parallel operation target signal; the first DC / DC unit 13 can control the first charge and discharge signal of the first battery pack body 11 according to the first control instruction, so that the battery pack body 11 charges or discharges through the first charge and discharge circuit 12 with the first charge and discharge signal; the second DC / DC unit 23 can control the second charge and discharge signal of the second battery pack body 21 according to the second control instruction, so that the second battery pack body 21 charges or discharges through the second charge and discharge circuit 22 with the second charge and discharge signal.

[0173] Optionally, Figure 11 is a schematic structural diagram of another energy storage system provided by an embodiment of the present invention; as Figure 11 shown, the first DC / DC unit 13 includes a first voltage detection sub-unit 131, a first DC / DC chip 132, and a first controller 133; the first voltage detection sub-unit 131 is connected to the first battery pack body 11, and is used to detect the voltage and remaining power of the first battery pack body 11 in real time; the first controller 133 is respectively connected to the first voltage detection sub-unit 131 and the first DC / DC chip 132, and is used to control the working states of the first DC / DC chip 132 and the first charge and discharge circuit 12 at least according to the voltage and remaining power of the first battery pack body 11. Specifically, the first controller 133 outputs a first charge and discharge control signal to the first DC / DC chip 132 according to the first control instruction and the voltage and remaining power of the first battery pack body 11, and the first DC / DC chip 132 controls the first charge and discharge signal of the first battery pack body 11, so that the first battery pack body 11 charges or discharges through the first charge and discharge circuit 12 with the first charge and discharge signal.

[0174] Optionally, continue to refer to Figure 11, the second DC / DC unit 23 includes a second voltage detection subunit 231, a second DC / DC chip 232, and a second controller 233; the second voltage detection subunit 231 is connected to the second battery pack body 21 for real-time detection of the voltage and remaining power of the second battery pack body 21; the second controller 233 is respectively connected to the second voltage detection subunit 231 and the second DC / DC chip 232, and is used to control the operating states of the second DC / DC chip 232 and the second charge and discharge circuit 22 at least according to the voltage and remaining power of the second battery pack body 21. Specifically, the second controller 233 outputs a second charge and discharge control signal to the second DC / DC chip 232 according to the second control instruction, the voltage, and the remaining power of the second battery pack body 21, and the second DC / DC chip 232 controls the second charge and discharge signal of the second battery pack body 21, so that the second battery pack body 21 is charged or discharged through the second charge and discharge circuit 22 with the second charge and discharge signal.

[0175] Optionally, in some embodiments, Figure 12 is a schematic structural diagram of another energy storage system provided by an embodiment of the present invention; as Figure 12 shown, the control module 30 is integrated in the first DC / DC unit 13 or the second DC / DC unit 23. Among them, integrating the control module 30 in the first DC / DC unit 13 or the second DC / DC unit 23 is beneficial to simplifying the system structure and can also simplify the overall control logic of the charge and discharge process of the energy storage system;

[0176] Here, taking the integration of the control module 30 in the first DC / DC unit 13 as an example for illustration, when the control module 30 is integrated in the first DC / DC unit 13, the first DC / DC unit 13 can detect the voltage and remaining capacity of the first battery pack 10 in real time, and can also detect the voltage and remaining capacity of the second battery pack 20 in real time. In this way, when the first DC / DC unit 13 determines that the first battery pack 10 and the second battery pack 20 meet the parallel operation conditions according to the voltage and remaining power of the first battery pack 10 and the voltage and remaining power of the second battery pack 20, it controls the connection with the second DC / DC unit 23 through a parallel operation cable, so that the first battery pack 10 and the second battery pack 20 complete parallel operation; after the first battery pack and the second battery pack are in parallel operation, it can also obtain a parallel operation target signal, and control the first charge and discharge signal of the first battery pack body 11 according to the current voltage of the first battery pack 10, the current voltage of the second battery pack 20, and the parallel operation target signal; and control the second charge and discharge signal of the second battery pack body 21 through the second DC / DC unit 23; in this way, the first battery pack 10 has the instruction control ability for the second battery pack, realizing the unified management of the entire system; at this time, the first battery pack 10 can be used as the main battery pack, and the second battery pack 20 can be used as the extended battery pack.

[0177] Of course, it can be understood that the second battery pack 20 can also be used as the main battery pack, and the first battery pack 10 can be used as an extended battery pack. This embodiment does not make specific limitations in this regard; in some embodiments, the energy storage system may further include multiple other extended battery packs; the main battery pack also has the ability to control other extended battery packs by instructions.

[0178] Note that the above is only a preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments only. Without departing from the concept of the present invention, it may further include more other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for controlling charging and discharging of an energy storage system, characterized in that: The energy storage system comprises a first battery pack and a second battery pack; the first battery pack and the second battery pack are connected via a parallel cable; and is characterized in that it comprises: Acquire the voltage and remaining power of the first battery pack and the voltage and remaining power of the second battery pack in real time; When it is determined that the first battery pack and the second battery pack meet the parallel connection condition according to the voltage and the remaining power of the first battery pack and the voltage and the remaining power of the second battery pack, controlling the first battery pack and the second battery pack to be connected in parallel; After the first battery pack and the second battery pack are connected in parallel, obtaining a parallel target signal; The charge and discharge signal of the first battery pack and the charge and discharge signal of the second battery pack are determined according to the current voltage of the first battery pack, the current voltage of the second battery pack, and a parallel target signal.

2. The energy storage system charge and discharge control method according to claim 1, characterized in that: The parallel target signal includes a discharge target power; Determining a charge and discharge signal of the first battery pack and a charge and discharge signal of the second battery pack according to a current voltage of the first battery pack, a current voltage of the second battery pack, and a parallel target signal, including: Determining an output power distribution ratio between the first battery pack and the second battery pack according to a current voltage of the first battery pack and a current voltage of the second battery pack; According to the output power allocation ratio and the discharge target power, the output power of the first battery pack and the output power of the second battery pack are determined respectively.

3. The energy storage system charge and discharge control method according to claim 2, characterized in that: Determining an output power distribution ratio between the first battery pack and the second battery pack according to a current voltage of the first battery pack and a current voltage of the second battery pack includes: Determining a difference range to which the voltage difference belongs according to a voltage difference between a current voltage of the first battery pack and a current voltage of the second battery pack; According to the difference range to which the voltage difference belongs, an output power distribution ratio between the first battery pack and the second battery pack is determined.

4. The energy storage system charge and discharge control method according to claim 3, characterized in that: When the voltage difference is greater than or equal to 0, the output power allocation ratio is greater than or equal to 1; When the voltage difference is less than 0, the output power allocation ratio is less than 1.

5. The energy storage system charge and discharge control method according to claim 3, characterized in that: Different difference ranges correspond to different output power allocation ratios.

6. The energy storage system charge and discharge control method according to claim 3, characterized in that: Determining an output power distribution ratio between the first battery pack and the second battery pack according to a difference range to which the voltage difference belongs, includes: When the voltage difference belongs to a difference range of the first difference range, determining that the output power distribution ratio of the first battery pack and the second battery pack is a first ratio; When the voltage difference value belongs to a second difference range, determining that the output power distribution ratio of the first battery pack and the second battery pack is a second ratio; The lower limit of the first difference range is greater than or equal to the upper limit of the second difference range, and the first ratio is greater than the second ratio.

7. The energy storage system charge and discharge control method according to claim 1, characterized in that: The parallel target signal includes a total charging current; Determining a charge and discharge signal of the first battery pack and a charge and discharge signal of the second battery pack according to a current voltage of the first battery pack, a current voltage of the second battery pack, and a parallel target signal, including: Determining a charging current distribution ratio of the first battery pack and the second battery pack according to a current voltage of the first battery pack and a current voltage of the second battery pack; A charging current of the first battery pack and a charging current of the second battery pack are determined respectively according to the total charging current and the charging current distribution ratio.

8. The energy storage system charge and discharge control method according to claim 7, characterized in that: Determining a charging current distribution ratio of the first battery pack and the second battery pack according to a current voltage of the first battery pack and a current voltage of the second battery pack includes: determining a first charging current ratio of the first battery pack according to a voltage difference between a current voltage of the first battery pack and a current voltage of the second battery pack; A second charging current ratio of the second battery pack is determined based on the first charging current ratio; wherein the sum of the first charging current ratio and the second charging current ratio is less than or equal to 1.

9. The energy storage system charge and discharge control method according to claim 8, characterized in that: Determining a first charging current ratio of the first battery pack according to a voltage difference between a current voltage of the first battery pack and a current voltage of the second battery pack includes: Constructing a charging current distribution ratio model; wherein the charging current factor distribution model is an increasing function; Substitute the difference between the current voltage of the first battery pack and the current voltage of the second battery pack into the charging current distribution ratio model to calculate a first charging current ratio of the first battery pack.

10. The energy storage system charge and discharge control method according to claim 1, characterized in that: The parallel condition includes that an initial difference between an initial voltage of the first battery pack and an initial voltage of the second battery pack is less than a preset voltage threshold, and an initial difference between an initial remaining power of the first battery pack and an initial remaining power of the second battery pack is less than a preset power threshold.

11. The energy storage system charge and discharge control method according to claim 1, characterized in that: Before controlling the first battery pack and the second battery pack to be connected in parallel, the method further includes: Determining whether the first battery pack and the second battery pack meet a parallel connection condition according to the voltage and the remaining power of the first battery pack and the voltage and the remaining power of the second battery pack; If not, the initial voltage of the first battery pack and the initial voltage of the second battery pack are both adjusted to the target voltage.

12. The energy storage system charge and discharge control method according to claim 11, characterized in that: Adjusting the initial voltage of the first battery pack and the initial voltage of the second battery pack to a target voltage includes: The initial voltage of the first battery pack and the initial voltage of the second battery pack are adjusted at a preset voltage adjustment rate until the initial voltage of the first battery pack and the initial voltage of the second battery pack are both the target voltage.

13. An energy storage system, characterized in that: include: A first battery pack, a second battery pack and a control module; the first battery pack and the second battery pack are electrically connected via a parallel cable; The first battery pack includes at least a first battery pack body, and the second battery pack includes at least a second battery pack body; the control module is connected to the first battery pack body and the second battery pack body respectively; the control module is used to execute the energy storage system charging and discharging control method described in any one of claims 1-12.

14. The energy storage system according to claim 13, characterized in that: The first battery pack further includes a first charge and discharge circuit and a first DC / DC unit; the second battery pack further includes a second charge and discharge circuit and a second DC / DC unit; The first battery pack body is connected to the first DC / DC unit via the first charge and discharge circuit; the second battery pack body is connected to the second DC / DC unit via the second charge and discharge circuit; The first DC / DC unit and the second DC / DC unit are both electrically connected to the parallel cable; The first DC / DC unit is used to detect the voltage and remaining capacity of the first battery pack in real time; The second DC / DC unit is used to detect the voltage and remaining capacity of the second battery pack in real time.

15. The energy storage system according to claim 14, characterized in that: The first DC / DC unit includes a first voltage detection subunit, a first DC / DC chip and a first controller; The first voltage detection subunit is connected to the first battery pack body and is used to detect the voltage and remaining power of the first battery pack body in real time; The first controller is connected to the first voltage detection subunit and the first DC / DC chip respectively, and is used to control the working state of the first DC / DC chip and the first charging and discharging circuit according to at least the voltage and remaining power of the first battery pack body.

16. The energy storage system according to claim 14, characterized in that: The second DC / DC unit includes a second voltage detection subunit, a second DC / DC chip and a second controller; The second voltage detection subunit is connected to the second battery pack body and is used to detect the voltage and remaining power of the second battery pack body in real time; The second controller is connected to the second voltage detection subunit and the second DC / DC chip respectively, and is used to control the working state of the second DC / DC chip and the second charging and discharging circuit according to at least the voltage and remaining power of the second battery pack body.

17. The energy storage system according to claim 14, characterized in that: The control module is integrated in the first DC / DC unit or the second DC / DC unit.

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