Energy storage system and control method thereof

Abstract

The disclosed embodiments relate to the field of energy storage technology and provide an energy storage system and a control method thereof, which at least helps to solve the problem of inconsistent coolant flow to each battery pack due to different viscosities of the coolant in the energy storage system, thereby significantly improving the uniformity of the temperature of the battery cells in each battery pack and extending the service life of the battery cells. The energy storage system includes: a battery management module, a liquid cooling unit, and multiple battery clusters; the liquid outlet of the liquid cooling unit is connected to the liquid inlet of each battery cluster; in each battery cluster, the liquid inlet of each battery pack is connected to the liquid inlet of the battery cluster to which it belongs, and a flow valve is provided at the liquid inlet of each battery pack, and the liquid outlet of each battery pack is connected to the liquid outlet of the battery cluster to which it belongs; the battery management module is used to perform the following steps: a coolant temperature determination step; a flow valve opening control step; a battery cell average temperature determination step; and an opening adjustment step.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of energy storage technology, and in particular to an energy storage system and a control method thereof. Background Art

[0002] With the continuous development of energy storage technology, the application of energy storage systems is becoming increasingly widespread. Energy storage systems are equipped with multiple battery packs, which are generally composed of multiple battery cells connected in series. The battery cells generate heat during the charging and discharging process, causing the battery temperature to rise. Failure to control the battery cell temperature can lead to reduced efficiency, shortened lifespan, or thermal runaway. Because natural heat dissipation of the battery cells cannot maintain the temperature within the operating range, a cooling system is necessary.

[0003] Liquid cooling is a common cooling method for energy storage systems. Liquid cooling lines are arranged throughout the system and coolant is introduced to keep the battery cell temperature within the operating range. Due to the influence of ambient temperature, battery operating conditions, and the operating state of the liquid cooling unit, the temperature of the coolant (e.g., ethylene glycol solution) varies under different operating conditions. This difference in coolant temperature leads to differences in viscosity, which in turn leads to inconsistent coolant flow to each battery pack. This reduces the temperature uniformity of the battery cells in each pack and shortens the battery cell life. Summary of the Invention

[0004] The embodiments of the present disclosure provide an energy storage system and a control method thereof, which at least help to solve the problem of inconsistent coolant flow to each battery pack due to different viscosities of the coolant in the energy storage system, thereby significantly improving the temperature uniformity of the battery cells in each battery pack and extending the service life of the battery cells.

[0005] According to some embodiments of the present disclosure, an energy storage system is provided, comprising: a battery management module, a liquid cooling unit, and a plurality of battery clusters; the battery clusters comprise a plurality of battery packs, each of which is provided with a plurality of battery cells;

[0006] The liquid outlet of the liquid cooling unit is connected to the liquid inlet of each battery cluster; in each battery cluster, the liquid inlet of each battery pack is connected to the liquid inlet of the battery cluster to which it belongs, a flow valve is provided at the liquid inlet of each battery pack, and the liquid outlet of each battery pack is connected to the liquid outlet of the battery cluster to which it belongs; the liquid outlet of each battery cluster is connected to the liquid inlet of the liquid cooling unit;

[0007] In each of the battery clusters, each of the battery packs is provided with a plurality of battery core temperature detection devices, each of the battery core temperature detection devices being used to detect the temperature of the corresponding battery core;

[0008] The plurality of flow valves and the plurality of battery core temperature detection devices are electrically connected to the battery management module respectively;

[0009] The battery management module is used to perform the following steps:

[0010] Coolant temperature determining step: determining coolant temperature information;

[0011] The flow valve opening control step includes: controlling the opening of each flow valve according to the coolant temperature information based on the coolant temperature and flow valve opening relationship table;

[0012] The step of determining the average battery cell temperature is as follows: determining the average temperature of each battery cell in the battery pack and the average temperature of all the battery cells according to the battery cell temperatures detected by all the battery cell temperature detection devices;

[0013] Opening adjustment step: if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells is greater than a preset deviation value, the opening of the flow valve corresponding to the battery pack is adjusted according to the adjustment function; wherein the adjustment function and the average temperature difference are positively correlated, and the positive and negative signs of the adjustment function and the average temperature difference are the same, and the average temperature difference is the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells.

[0014] According to some embodiments of the present disclosure, the battery management module performing the opening adjustment step includes:

[0015] The initial opening adjustment value determination step includes: if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells is greater than the preset deviation value, obtaining the initial opening adjustment value according to the adjustment function;

[0016] Step for determining the opening adjustment value: determining the opening adjustment value of the flow valve corresponding to the battery pack based on the size relationship between the initial opening adjustment value and the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, wherein the preset opening adjustment upper limit value is greater than the preset opening adjustment lower limit value.

[0017] According to some embodiments of the present disclosure, the battery management module performs the step of determining the opening adjustment value, including:

[0018] If the initial opening adjustment value is between the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, the opening of the flow valve corresponding to the battery pack is adjusted according to the initial opening adjustment value.

[0019] According to some embodiments of the present disclosure, the battery management module performs the step of determining the opening adjustment value, including:

[0020] If the initial opening adjustment value is greater than or equal to the preset opening adjustment upper limit value, adjusting the opening of the flow valve corresponding to the battery pack according to the preset opening adjustment upper limit value;

[0021] If the initial opening adjustment value is less than or equal to the preset opening adjustment lower limit value, the opening of the flow valve corresponding to the battery pack is adjusted according to the preset opening adjustment lower limit value.

[0022] According to some embodiments of the present disclosure, in the opening adjustment step,

[0023] In the average temperature difference (Tpavg n -Tavg) is greater than zero, the adjustment function F(Tpavg n -Tavg) satisfies:

[0024]

[0025] In the average temperature difference (Tpavg n -Tavg) is less than zero, the adjustment function F(Tpavg n -Tavg) satisfies:

[0026]

[0027] Among them, a, b, and c are all constants, and 0 <a<1,c> 0, b>0; Tpavg n represents the average temperature of the battery cells in any of the battery packs, and Tavg represents the average temperature of all the battery cells.

[0028] According to some embodiments of the present disclosure, a first temperature detection device is provided inside the liquid cooling unit, and the first temperature detection device is used to detect the temperature of the coolant flowing out of the liquid outlet of the liquid cooling unit and output a first temperature signal to the battery management module;

[0029] The energy storage system further includes a second temperature detection device. Each battery pack is further provided with a liquid cooling plate. The second temperature detection device is disposed on a side of the liquid cooling plate corresponding to the battery pack close to the liquid cooling unit. The second temperature detection device is configured to detect the temperature of the coolant flowing into the liquid inlet of the corresponding battery pack and output a second temperature signal to the battery management module.

[0030] The first temperature detection device and the second temperature detection device are electrically connected to the battery management module respectively;

[0031] The battery management module is used to perform the coolant temperature determination step, which includes:

[0032] determining whether the first temperature detection device is in a normal state;

[0033] If yes, determining the coolant temperature information according to the first temperature signal;

[0034] If not, the coolant temperature information is determined according to the second temperature signal.

[0035] According to some embodiments of the present disclosure, another aspect of the present disclosure provides a control method based on the above energy storage system, including:

[0036] Coolant temperature determining step: determining coolant temperature information;

[0037] The flow valve opening control step includes: controlling the opening of each flow valve according to the coolant temperature information based on the coolant temperature and flow valve opening relationship table;

[0038] The step of determining the average battery cell temperature is as follows: determining the average temperature of each battery cell in the battery pack and the average temperature of all the battery cells according to the battery cell temperatures detected by all the battery cell temperature detection devices;

[0039] Opening adjustment step: if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells is greater than a preset deviation value, the opening of the flow valve corresponding to the battery pack is adjusted according to the adjustment function; wherein the adjustment function and the average temperature difference are positively correlated, and the positive and negative signs of the adjustment function and the average temperature difference are the same, and the average temperature difference is the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells.

[0040] According to some embodiments of the present disclosure, the opening adjustment step includes:

[0041] The initial opening adjustment value determination step includes: if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells is greater than the preset deviation value, obtaining the initial opening adjustment value according to the adjustment function;

[0042] Step for determining the opening adjustment value: determining the opening adjustment value of the flow valve corresponding to the battery pack based on the size relationship between the initial opening adjustment value and the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, wherein the preset opening adjustment upper limit value is greater than the preset opening adjustment lower limit value.

[0043] According to some embodiments of the present disclosure, the step of determining the opening adjustment value includes:

[0044] If the initial opening adjustment value is between the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, adjusting the opening of the flow valve corresponding to the battery pack according to the initial opening adjustment value;

[0045] If the initial opening adjustment value is greater than or equal to the preset opening adjustment upper limit value, adjusting the opening of the flow valve corresponding to the battery pack according to the preset opening adjustment upper limit value;

[0046] If the initial opening adjustment value is less than or equal to the preset opening adjustment lower limit value, the opening of the flow valve corresponding to the battery pack is adjusted according to the preset opening adjustment lower limit value.

[0047] According to some embodiments of the present disclosure, in the opening adjustment step,

[0048] In the average temperature difference (Tpavg n -Tavg) is greater than zero, the adjustment function F(Tpavg n -Tavg) satisfies:

[0049]

[0050] In the average temperature difference (Tpavg n -Tavg) is less than zero, the adjustment function F(Tpavgn-Tavg) satisfies:

[0051]

[0052] Among them, a, b, and c are all constants, and 0 <a<1,c> 0, b>0; Tpavg n represents the average temperature of the battery cells in any of the battery packs, and Tavg represents the average temperature of all the battery cells.

[0053] The disclosed embodiments provide an energy storage system and a control method thereof. In the energy storage system, on the one hand, a battery management module controls the opening of each flow valve according to coolant temperature information based on a relationship table between coolant temperature and flow valve opening, so as to ensure that the coolant flow to each battery pack is consistent, thereby solving the problem of inconsistent coolant flow to each battery pack due to different coolant viscosities, thereby significantly improving the uniformity of the temperature of the battery cells in each battery pack and extending the service life of the battery cells; on the other hand, when the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells is greater than a preset deviation value, the battery management module further adjusts the opening of the flow valve of the corresponding battery pack according to an adjustment function, so that the average temperature of the battery cells in each battery pack is more consistent, thereby further improving the uniformity of the temperature of the battery cells in each battery pack and further extending the service life of the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 A schematic structural diagram of an energy storage system provided in an embodiment of the present disclosure;

[0056] Figure 2 A schematic structural diagram of a battery pack provided in an embodiment of the present disclosure;

[0057] Figure 3 A flow chart of a control method for an energy storage system provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of the present disclosure more clear, the technical solutions of the present disclosure will be clearly and completely described below in conjunction with the specific embodiments of the present disclosure and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present disclosure.

[0059] In the description of the embodiments of the present disclosure, “at least one” means one or more, and “a plurality of” means two or more, unless otherwise clearly and specifically defined.

[0060] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0061] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0062] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present disclosure. For example, if the device or element in the figure is inverted, then the element described as being "below" or "below" or "below" or "bottom" of other elements or features will be oriented "above" or "top" of the other elements or features. Therefore, the term "below" can encompass both above and below orientations depending on the context in which the term is used, which will be obvious to a person skilled in the art. The material can be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatially relative descriptors used herein can be interpreted accordingly.

[0063] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0064] In the description of the embodiments of the present disclosure, when a component “includes” another component, unless otherwise stated, it does not exclude other components, and other components may be further included.

[0065] The present disclosure provides an energy storage system, referring to Figure 1 and Figure 2 As shown, it includes: a battery management module 3, a liquid cooling unit 1 and multiple battery clusters 2; the battery cluster 2 includes multiple battery packs 21, and the battery pack 21 is provided with multiple battery cells 212.

[0066] refer to Figure 1 As shown, the liquid outlet of the liquid cooling unit 1 is connected to the liquid inlet of each battery cluster 2; in each battery cluster 2, the liquid inlet of each battery pack 21 is connected to the liquid inlet of the battery cluster to which it belongs, a flow valve 211 is provided at the liquid inlet of each battery pack 21, and the liquid outlet of each battery pack 21 is connected to the liquid outlet of the battery cluster to which it belongs; the liquid outlet of each battery cluster 2 is connected to the liquid inlet of the liquid cooling unit 1.

[0067] refer to Figure 2 As shown, in each battery cluster, each battery pack is provided with a plurality of battery cell temperature detection devices 213 , each battery cell temperature detection device 213 is used to detect the temperature of the corresponding battery cell 212 ; the plurality of flow valves and the plurality of battery cell temperature detection devices 213 are electrically connected to the battery management module 3 , respectively.

[0068] The connection method of the above-mentioned multiple battery clusters is not limited. For example, the multiple battery clusters can be as follows: Figure 1 The parallel arrangement shown is of course also possible in other arrangements according to actual requirements. In each battery cluster, multiple battery packs can be arranged in series; in each battery pack, multiple battery cells can be arranged in series.

[0069] The liquid outlet of the liquid cooling unit and the liquid inlet of each battery cluster can be connected by Figure 1 The primary pipeline a1 shown is connected; in each battery cluster, the liquid inlet of each battery pack and the liquid inlet of the battery cluster to which it belongs can be connected through Figure 1 The liquid outlet of each battery pack and the liquid outlet of the battery cluster to which it belongs can be connected by the following method: Figure 1 The liquid outlet of each battery cluster and the liquid inlet of the liquid cooling unit can be connected by the secondary pipeline b2 shown in FIG. Figure 1 The primary pipeline b1 is shown as connected. In order to better control the flow rate and transmission efficiency of the coolant, the diameter of the primary pipeline can be larger than that of the secondary pipeline.

[0070] The specific type of the flow valve is not limited, and the flow valve can achieve different opening degrees under the control of the battery management module; for example, the flow valve can be an electromagnetic flow valve.

[0071] The specific structure of the liquid cooling unit is not limited. For example, the liquid cooling unit may include a liquid cooling unit.

[0072] The specific location of the multiple battery cell temperature detection devices in each battery pack is not limited. In order to more accurately detect the temperature of the battery cell, the battery cell temperature detection device can be set on one side surface of the battery cell (for example: Figure 2 To reduce costs, the number of cell temperature detection devices in each battery pack can be less than the number of cells. To ensure detection effectiveness, at least one of the 3-5 cells can be equipped with a cell temperature detection device. To obtain a more accurate average temperature of the cells in the battery pack, the multiple cell temperature detection devices are evenly distributed. Figure 3 In the figure, a battery temperature detection device is installed on one of the five battery cells. Figure 3The six cell temperature detection devices 213 are evenly distributed. The specific structure of the cell temperature detection device is not limited. For example, the cell temperature detection device may include a temperature sensor, which can transmit the detected cell temperature information to the battery management module.

[0073] refer to Figure 2 As shown, each battery pack can also be provided with a liquid cooling plate 214, and a plurality of battery cells 212 can be provided on the upper side of the liquid cooling plate 214. A pipeline can be provided inside the liquid cooling plate 214 to cool the plurality of battery cells 212. A flow valve can be provided at the liquid inlet position of the liquid cooling plate pipeline; and the liquid outlet of the liquid cooling plate pipeline is connected to the liquid outlet of the battery cluster to which it belongs.

[0074] The specific structure of the above-mentioned battery management module is not limited. For example, the battery management module may include an MCU (Microcontroller Unit) chip, an FPGA (Field Programmable Gate Array) chip or an ARM (Advanced RISC Machines) chip. Of course, other types of chips may also be included.

[0075] refer to Figure 3 As shown, the battery management module is used to perform the following steps:

[0076] S1. Coolant temperature determination step: determining the coolant temperature information. The specific method for determining the coolant temperature information is not limited here. For example, a temperature sensor may be used to detect the temperature of the coolant in the liquid cooling unit.

[0077] S2, flow valve opening control step: Based on the coolant temperature and flow valve opening relationship table, the opening of each flow valve is controlled according to the coolant temperature information.

[0078] The above-mentioned relationship table between the coolant temperature and the flow valve opening can be obtained in advance through a large number of experiments or simulations and stored in the battery management module.

[0079] The following provides a specific table of the relationship between coolant temperature and flow valve opening.

[0080] Table 1

[0081] Temperature / ℃ -25～-15 -15～-5 -5～5 5～15 15～25 25～35 35～45 45～55 Viscosity / mPa*s 22.07 12.74 8.09 5.50 3.94 2.94 2.26 1.78 Valve opening Working condition 1 Working condition 2 Working condition 3 Working condition 4 Working condition 5 Working condition 6 Working condition 7 Working condition 8

[0082] As shown in Table 1, the lower the temperature of the coolant, the greater the viscosity, and the corresponding valve opening conditions are different, that is, the opening of the flow valve is different. The valve opening in Table 1 refers to the degree of valve opening, and the value is generally between 0 and 1, or it can also be expressed as 0% to 100%; where the valve is fully closed and the valve is fully open. The specific valve opening corresponding to each working condition in Table 1 above can be obtained based on experiments or simulations. There is a certain relationship between valve opening and flow. Based on the relationship table between coolant temperature and flow valve opening, by adjusting the opening of each flow valve, the coolant flow to each battery pack can be guaranteed to be consistent.

[0083] S3, step of determining the average battery cell temperature: determining the average temperature of the battery cells in each battery pack and the average temperature of all battery cells based on the battery cell temperatures detected by all battery cell temperature detection devices.

[0084] The average temperature of the battery cells in each battery pack can be obtained by taking the average temperature value detected by all battery cell temperature detection devices in each battery pack; the average temperature of all battery cells can be obtained by taking the average temperature value detected by all battery cell temperature detection devices in all battery packs.

[0085] S4. Opening adjustment step: If the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells is greater than a preset deviation value, the opening of the flow valve of the corresponding battery pack is adjusted according to the adjustment function; wherein the adjustment function and the average temperature difference are positively correlated, and the adjustment function and the average temperature difference have the same positive and negative signs, and the average temperature difference is the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells.

[0086] In order to effectively ensure the uniformity of the temperature of each battery pack cell, the above-mentioned preset deviation value can be set within a certain range; for example, the value range of the preset deviation value can be [3°C, 5°C], and the preset deviation value can be 3°C, 4°C or 5°C, etc.

[0087] The specific form of the above-mentioned adjustment function is not limited, as long as it meets the corresponding requirements. For example, the adjustment function can be an exponential function, a logarithmic function, or a monotonically changing part of a sine function. The above-mentioned adjustment function and the average temperature difference are positively correlated, that is, the adjustment function increases as the average temperature difference increases, or the adjustment function decreases as the average temperature difference decreases. The above-mentioned adjustment function and the average temperature difference have the same positive and negative signs, which means that when the average temperature difference is greater than zero, the adjustment function is also greater than zero; or when the average temperature difference is less than zero, the adjustment function is also less than zero.

[0088] If the absolute value of the difference between the average temperature of the cells in any of the aforementioned battery packs and the average temperature of all the cells is greater than a preset deviation value, it indicates that the average temperature of the cells in the corresponding battery pack is too high or too low, which is not conducive to improving the temperature uniformity of the cells across all battery packs. Based on the adjustment function, the flow valve openings of the battery packs with excessively high or low average cell temperatures are further adjusted, thereby lowering the temperature of the battery pack with excessively high average cell temperatures or raising the temperature of the battery pack with excessively low average cell temperatures, thereby aligning the average cell temperatures of the various battery packs, further improving the temperature uniformity of the cells across all battery packs.

[0089] In the energy storage system provided by the embodiments of the present disclosure, on the one hand, the battery management module controls the opening of each flow valve according to the coolant temperature information based on the relationship table between the coolant temperature and the flow valve opening, so as to ensure that the coolant flow rate flowing to each battery pack tends to be consistent, thereby solving the problem of inconsistent coolant flow rate flowing to each battery pack due to different coolant viscosities, thereby greatly improving the uniformity of the temperature of the battery cells in each battery pack and extending the service life of the battery cells; on the other hand, when the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells is greater than a preset deviation value, the battery management module further adjusts the opening of the flow valve of the corresponding battery pack according to the adjustment function, so that the average temperature of the battery cells in each battery pack tends to be more consistent, thereby further improving the uniformity of the temperature of the battery cells in each battery pack and further extending the service life of the battery cells.

[0090] The total amount of coolant provided by the liquid cooling unit generally remains unchanged. If the opening of the battery pack is adjusted too much according to the adjustment function, it may have a significant impact on the flow of coolant to other battery packs. Therefore, to avoid this problem, in one or more embodiments, the battery management module performs S4, the opening adjustment step includes:

[0091] S41, initial opening adjustment value determination step: if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells is greater than a preset deviation value, the initial opening adjustment value is obtained according to the adjustment function.

[0092] S42, opening adjustment value determination step: determine the opening adjustment value of the flow valve corresponding to the battery pack based on the size relationship between the initial opening adjustment value and the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, wherein the preset opening adjustment upper limit value is greater than the preset opening adjustment lower limit value.

[0093] If the difference between the average temperature of the cells in any battery pack and the average temperature of all cells is positive, it indicates that the average temperature of the cells in the corresponding battery pack is too high and the flow valve opening needs to be further increased. The maximum increase in the opening is the preset opening adjustment upper limit. The preset opening adjustment upper limit can range from [10%, 15%]. For example, the preset opening adjustment upper limit can be 10%, 12%, 14%, or 15%.

[0094] If the difference between the average temperature of the cells in any battery pack and the average temperature of all cells is negative, it indicates that the average temperature of the cells in the corresponding battery pack is too low and the flow valve opening needs to be further reduced. The maximum value of the opening reduction is the preset opening adjustment lower limit. The preset opening adjustment lower limit can range from [-15%, -10%]. For example, the preset opening adjustment lower limit can be -10%, -12%, -14%, or -15%.

[0095] By setting a preset upper limit value for the opening adjustment and a preset lower limit value for the opening adjustment, it is possible to avoid making excessive adjustments to the opening of the battery pack, thereby ensuring that the coolant flow to each battery pack tends to be consistent and the average temperature of the battery cells in each battery pack tends to be consistent.

[0096] The following specifically describes how to determine the opening adjustment value of the flow valve corresponding to the battery pack based on the relationship between the initial opening adjustment value and the preset opening adjustment upper limit value and the preset opening adjustment lower limit value.

[0097] In one or more embodiments, the battery management module executes S42, the step of determining the opening adjustment value, including:

[0098] If the initial opening adjustment value is between the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, S421 is executed to adjust the opening of the flow valve of the corresponding battery pack according to the initial opening adjustment value.

[0099] Here, the initial opening adjustment value may be a positive value or a negative value; if the initial opening adjustment value is between the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, then the initial opening adjustment value determined according to the adjustment function can be directly used to adjust the opening of the flow valve of the corresponding battery pack, so that the average temperature of the battery cells in each battery pack is more consistent.

[0100] In one or more embodiments, the battery management module executes S42, the step of determining the opening adjustment value, including:

[0101] If the initial opening adjustment value is greater than or equal to the preset opening adjustment upper limit value, execute S422 to adjust the opening of the flow valve of the corresponding battery pack according to the preset opening adjustment upper limit value to avoid adjusting the opening of the flow valve of the corresponding battery pack too large.

[0102] If the initial opening adjustment value is less than or equal to the preset opening adjustment lower limit, execute S423 to adjust the opening of the flow valve of the corresponding battery pack according to the preset opening adjustment lower limit to avoid adjusting the opening of the flow valve of the corresponding battery pack to be too small.

[0103] The following provides a specific adjustment function, S4, in the opening adjustment step,

[0104] In the average temperature difference (Tpavg n -Tavg) is greater than zero, the adjustment function F(Tpavg n -Tavg) satisfies:

[0105]

[0106] In the average temperature difference (Tpavg n -Tavg) is less than zero, the adjustment function F(Tpavg n -Tavg) satisfies:

[0107]

[0108] Among them, a, b, and c are all constants, and 0 <a<1,c> 0, b>0; Tpavg n It represents the average temperature of the cells in any battery pack, and Tavg represents the average temperature of all cells.

[0109] The adjustment function is an exponential function, and the values ​​of the constants a, b, and c can be selected according to the situation. This function is simple in form and easy to control the upper limit or lower limit.

[0110] The following describes how to determine the coolant temperature information.

[0111] In one or more embodiments, a first temperature detection device is provided inside the liquid cooling unit, and the first temperature detection device is used to detect the temperature of the coolant flowing out of the liquid outlet of the liquid cooling unit and output a first temperature signal to the battery management module; the energy storage system also includes a second temperature detection device, reference Figure 2 As shown, each battery pack is also provided with a liquid cooling plate 214, and a second temperature detection device 215 is provided on a side of the liquid cooling plate 214 corresponding to the battery pack close to the liquid cooling unit; the second temperature detection device 215 is used to detect the temperature of the coolant flowing into the liquid inlet 2141 of the corresponding battery pack, and output a second temperature signal to the battery management module 3; the first temperature detection device and the second temperature detection device 215 are respectively electrically connected to the battery management module 3.

[0112] The above-mentioned energy storage system includes multiple battery clusters, each battery cluster includes multiple battery packs. The above-mentioned battery pack close to the liquid cooling unit refers to any battery pack in the battery cluster with the smallest distance from the liquid cooling unit. Of course, in order to obtain a more accurate coolant temperature, the second temperature detection device can be set in the battery cluster with the smallest distance from the liquid cooling unit, on the side of the liquid cooling plate corresponding to the battery pack closest to the liquid inlet position of the battery cluster.

[0113] The battery management module is used to execute S1, and the coolant temperature determination step includes:

[0114] S11. Determine whether the first temperature detection device is in a normal state. The specific determination method is not limited. For example, the determination can be based on whether a detection signal from the first temperature detection device is received. If the detection signal from the first temperature detection device is not received, it can be determined that the first temperature detection device is not in a normal state. Alternatively, the determination can be based on whether the received detection signal is within a normal range. If the voltage value or current value of the detection signal is not within the detection range, it can be determined that the first temperature detection device is not in a normal state. Of course, other determination methods are possible, which are not listed here.

[0115] If yes, then execute S12 and determine the coolant temperature information according to the first temperature signal; if no, execute S13 and determine the coolant temperature information according to the second temperature signal.

[0116] In the energy storage system provided by the embodiments of the present disclosure, two methods for obtaining coolant temperature information are provided by providing a first temperature detection device and a second temperature detection device. If the first temperature detection device fails, the temperature information detected by the second temperature detection device can be used as the coolant temperature information, significantly enhancing the redundancy and stability of the system.

[0117] Based on the same technical concept, the present disclosure also provides a control method based on the above energy storage system, referring to Figure 3 As shown, including:

[0118] S1. Coolant temperature determination step: determining the coolant temperature information. The specific method for determining the coolant temperature information is not limited here. For example, a temperature sensor may be used to detect the temperature of the coolant in the liquid cooling unit.

[0119] S2, flow valve opening control step: based on the coolant temperature and flow valve opening relationship table, control the opening of each flow valve according to the coolant temperature information;

[0120] S3, cell average temperature determination step: determining the average temperature of the cells in each battery pack and the average temperature of all cells based on the cell temperatures detected by all cell temperature detection devices;

[0121] S4. Opening adjustment step: If the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells is greater than a preset deviation value, the opening of the flow valve of the corresponding battery pack is adjusted according to the adjustment function; wherein the adjustment function and the average temperature difference are positively correlated, and the adjustment function and the average temperature difference have the same positive and negative signs, and the average temperature difference is the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells.

[0122] The energy storage system control method provided by the disclosed embodiments, on the one hand, by executing the coolant temperature determination step and the flow valve opening control step, can achieve, based on the coolant temperature and flow valve opening relationship table, controlling the opening of each flow valve according to coolant temperature information, to ensure that the coolant flow to each battery pack is consistent, thereby resolving the problem of inconsistent coolant flow to each battery pack due to different coolant viscosities, thereby significantly improving the uniformity of the temperature of the battery cells in each battery pack and extending the service life of the battery cells. On the other hand, by executing the battery cell average temperature determination step and the flow valve opening adjustment step, when the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all battery cells is greater than a preset deviation value, the flow valve opening of the corresponding battery pack is further adjusted according to the adjustment function to make the average temperature of the battery cells in each battery pack more consistent, thereby further improving the temperature uniformity of the battery cells in each battery pack and further extending the service life of the battery cells. This control method is simple and easy to implement.

[0123] It should be noted that for the relevant description of each step involved in the embodiments of the present disclosure, reference can be made to the aforementioned embodiments and will not be described again here.

[0124] The total amount of coolant provided by the liquid cooling unit generally remains unchanged. If the opening of the battery pack is adjusted too much according to the adjustment function, it may have a significant impact on the flow of coolant to other battery packs. Therefore, to avoid this problem, in one or more embodiments, S4, the opening adjustment step, includes:

[0125] S41, determining an initial opening adjustment value: if the absolute value of the difference between the average temperature of a cell in any battery pack and the average temperature of all cells is greater than a preset deviation value, obtaining an initial opening adjustment value according to an adjustment function;

[0126] S42, opening adjustment value determination step: determine the opening adjustment value of the flow valve corresponding to the battery pack based on the size relationship between the initial opening adjustment value and the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, wherein the preset opening adjustment upper limit value is greater than the preset opening adjustment lower limit value.

[0127] By setting a preset upper limit value for the opening adjustment and a preset lower limit value for the opening adjustment, it is possible to avoid making excessive adjustments to the opening of the battery pack, thereby ensuring that the coolant flow to each battery pack tends to be consistent and the average temperature of the battery cells in each battery pack tends to be consistent.

[0128] The following specifically describes how to determine the opening adjustment value of the flow valve corresponding to the battery pack based on the relationship between the initial opening adjustment value and the preset opening adjustment upper limit value and the preset opening adjustment lower limit value.

[0129] In one or more embodiments, S42, the step of determining the opening adjustment value includes:

[0130] If the initial opening adjustment value is between the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, execute S421 and adjust the opening of the flow valve of the corresponding battery pack according to the initial opening adjustment value so that the average temperature of the battery cells in each battery pack is more consistent.

[0131] If the initial opening adjustment value is greater than or equal to the preset opening adjustment upper limit value, execute S422 to adjust the opening of the flow valve of the corresponding battery pack according to the preset opening adjustment upper limit value to avoid adjusting the opening of the flow valve of the corresponding battery pack too large.

[0132] If the initial opening adjustment value is less than or equal to the preset opening adjustment lower limit, execute S423 to adjust the opening of the flow valve of the corresponding battery pack according to the preset opening adjustment lower limit to avoid adjusting the opening of the flow valve of the corresponding battery pack to be too small.

[0133] The following provides a specific adjustment function, S4, in the opening adjustment step,

[0134] In the average temperature difference (Tpavg n -Tavg) is greater than zero, the adjustment function F(Tpavg n -Tavg) satisfies:

[0135]

[0136] In the average temperature difference (Tpavg n -Tavg) is less than zero, the adjustment function F(Tpavgn-Tavg) satisfies:

[0137]

[0138] Among them, a, b, and c are all constants, and 0 <a<1,c> 0, b>0; Tpavg n It represents the average temperature of the cells in any battery pack, and Tavg represents the average temperature of all cells.

[0139] The adjustment function is an exponential function, and the values ​​of the constants a, b, and c can be selected according to the situation. This function is simple in form and easy to control the upper limit or lower limit.

[0140] In one or more embodiments, S1, the coolant temperature determination step includes:

[0141] S11. Determine whether the first temperature detection device is in a normal state. The specific determination method is not limited. For example, the determination can be based on whether a detection signal from the first temperature detection device is received. If the detection signal from the first temperature detection device is not received, it can be determined that the first temperature detection device is not in a normal state. Alternatively, the determination can be based on whether the received detection signal is within a normal range. If the voltage value or current value of the detection signal is not within the detection range, it can be determined that the first temperature detection device is not in a normal state. Of course, other determination methods are possible, which are not listed here.

[0142] If yes, then execute S12 and determine the coolant temperature information according to the first temperature signal; if no, execute S13 and determine the coolant temperature information according to the second temperature signal.

[0143] The above control method provides two methods for obtaining coolant temperature information. When the first temperature detection device fails, the temperature information detected by the second temperature detection device can be used as the coolant temperature information, which greatly enhances the redundancy and stability of the system.

[0144] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the scope defined in the claims.

Claims

1. An energy storage system, characterized in that: include: A battery management module, a liquid cooling unit, and a plurality of battery clusters; the battery clusters include a plurality of battery packs, each of which is provided with a plurality of battery cells; The liquid outlet of the liquid cooling unit is connected to the liquid inlet of each battery cluster; in each battery cluster, the liquid inlet of each battery pack is connected to the liquid inlet of the battery cluster to which it belongs, a flow valve is provided at the liquid inlet of each battery pack, and the liquid outlet of each battery pack is connected to the liquid outlet of the battery cluster to which it belongs; the liquid outlet of each battery cluster is connected to the liquid inlet of the liquid cooling unit; In each of the battery clusters, each of the battery packs is provided with a plurality of battery core temperature detection devices, each of the battery core temperature detection devices being used to detect the temperature of the corresponding battery core; The plurality of flow valves and the plurality of battery core temperature detection devices are electrically connected to the battery management module respectively; The battery management module is used to perform the following steps: Coolant temperature determining step: determining coolant temperature information; The flow valve opening control step includes: controlling the opening of each flow valve according to the coolant temperature information based on the coolant temperature and flow valve opening relationship table; The step of determining the average battery cell temperature is as follows: determining the average temperature of each battery cell in the battery pack and the average temperature of all the battery cells according to the battery cell temperatures detected by all the battery cell temperature detection devices; Opening adjustment step: if the absolute value of the difference between the average temperature of the battery cells in any of the battery packs and the average temperature of all the battery cells is greater than the preset deviation value, the opening of the flow valve corresponding to the battery pack is adjusted according to the adjustment function; wherein the adjustment function and the average temperature difference are positively correlated, and the positive and negative signs of the adjustment function and the average temperature difference are the same, and the average temperature difference is the difference between the average temperature of the battery cells in any of the battery packs and the average temperature of all the battery cells; if the absolute value of the difference between the average temperature of the battery cells in any of the battery packs and the average temperature of all the battery cells is greater than the preset deviation value, Assuming a deviation value, an initial opening adjustment value is obtained according to the adjustment function; if the initial opening adjustment value is between a preset opening adjustment upper limit value and a preset opening adjustment lower limit value, the opening of the flow valve corresponding to the battery pack is adjusted according to the initial opening adjustment value; if the initial opening adjustment value is greater than or equal to the preset opening adjustment upper limit value, the opening of the flow valve corresponding to the battery pack is adjusted according to the preset opening adjustment upper limit value; if the initial opening adjustment value is less than or equal to the preset opening adjustment lower limit value, the opening of the flow valve corresponding to the battery pack is adjusted according to the preset opening adjustment lower limit value; In the opening adjustment step, In the average temperature difference (Tpavg n -Tavg) is greater than zero, the adjustment function F (Tpavg n -Tavg) satisfies: In the average temperature difference (Tpavg n -Tavg) is less than zero, the adjustment function F (Tpavg n -Tavg) satisfies: Among them, a, b, and c are all constants, and 0 <a<1,c> 0, b>0; Tpavg n represents the average temperature of the battery cells in any of the battery packs, and Tavg represents the average temperature of all the battery cells.

2. The energy storage system according to claim 1, characterized in that A first temperature detection device is provided inside the liquid cooling unit, and the first temperature detection device is used to detect the temperature of the coolant flowing out of the liquid outlet of the liquid cooling unit and output a first temperature signal to the battery management module; The energy storage system further includes a second temperature detection device. Each battery pack is further provided with a liquid cooling plate. The second temperature detection device is disposed on a side of the liquid cooling plate corresponding to the battery pack close to the liquid cooling unit. The second temperature detection device is configured to detect the temperature of the coolant flowing into the liquid inlet of the corresponding battery pack and output a second temperature signal to the battery management module. The first temperature detection device and the second temperature detection device are electrically connected to the battery management module respectively; The battery management module is used to perform the coolant temperature determination step, which includes: determining whether the first temperature detection device is in a normal state; If yes, determining the coolant temperature information according to the first temperature signal; If not, the coolant temperature information is determined according to the second temperature signal.

3. A control method for an energy storage system, characterized in that: The energy storage system includes: a battery management module, a liquid cooling unit and a plurality of battery clusters; the battery cluster includes a plurality of battery packs, and the battery packs are provided with a plurality of battery cells; The liquid outlet of the liquid cooling unit is connected to the liquid inlet of each battery cluster; in each battery cluster, the liquid inlet of each battery pack is connected to the liquid inlet of the battery cluster to which it belongs, a flow valve is provided at the liquid inlet of each battery pack, and the liquid outlet of each battery pack is connected to the liquid outlet of the battery cluster to which it belongs; the liquid outlet of each battery cluster is connected to the liquid inlet of the liquid cooling unit; In each of the battery clusters, each of the battery packs is provided with a plurality of battery core temperature detection devices, each of the battery core temperature detection devices being used to detect the temperature of the corresponding battery core; The plurality of flow valves and the plurality of battery core temperature detection devices are electrically connected to the battery management module respectively; The control method of the energy storage system includes: Coolant temperature determining step: determining coolant temperature information; The flow valve opening control step includes: controlling the opening of each flow valve according to the coolant temperature information based on the coolant temperature and flow valve opening relationship table; The step of determining the average battery cell temperature is as follows: determining the average temperature of each battery cell in the battery pack and the average temperature of all the battery cells according to the battery cell temperatures detected by all the battery cell temperature detection devices; The opening adjustment step includes: if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells is greater than a preset deviation value, adjusting the opening of the flow valve corresponding to the battery pack according to the adjustment function; wherein the adjustment function and the average temperature difference are positively correlated, and the positive and negative signs of the adjustment function and the average temperature difference are the same, and the average temperature difference is the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells; if the absolute value of the difference between the average temperature of the battery cells in any battery pack and the average temperature of all the battery cells is greater than the preset deviation value, obtaining an initial opening adjustment value according to the adjustment function; if the initial opening adjustment value is between the preset opening adjustment upper limit value and the preset opening adjustment lower limit value, adjusting the opening of the flow valve corresponding to the battery pack according to the initial opening adjustment value; if the initial opening adjustment value is greater than or equal to the preset opening adjustment upper limit value, adjusting the opening of the flow valve corresponding to the battery pack according to the preset opening adjustment upper limit value; In the opening adjustment step, In the average temperature difference (Tpavg n -Tavg) is greater than zero, the adjustment function F (Tpavg n -Tavg) satisfies: In the average temperature difference (Tpavg n -Tavg) is less than zero, the adjustment function F(Tpavgn-Tavg) satisfies: Among them, a, b, and c are all constants, and 0 <a<1,c> 0, b>0; Tpavg n represents the average temperature of the battery cells in any of the battery packs, and Tavg represents the average temperature of all the battery cells.

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