Comparison test method for verifying performance of liquid cooling unit

Abstract

The invention discloses a comparison test method for verifying the performance of a liquid cooling unit, and belongs to the technical field of new energy. The method comprises the following steps: enabling a first energy storage container system configured with a first liquid cooling unit and a second energy storage container system configured with a second liquid cooling unit to respectively meet test conditions; respectively testing each energy storage container system under the first, second and third charging and discharging test working conditions, and respectively enabling each liquid cooling unit to correspondingly execute a first liquid cooling strategy, a second liquid cooling strategy and a third liquid cooling strategy during testing, so as to obtain a stack-level cell temperature data set and a liquid cooling unit outlet water temperature data set; the refrigeration performance of the liquid cooling unit is compared according to the two data sets, and the optimal liquid cooling unit is determined; the charge-discharge rate in the first charge-discharge test working condition is smaller than that in the third charge-discharge test working condition; the highest temperature of the battery cell monomer required for starting the first liquid cooling strategy is higher than that of the second liquid cooling strategy. According to the scheme, the performance of the liquid cooling unit can be verified, and optimal configuration of the liquid cooling unit of the energy storage container system is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy, and in particular relates to a comparative test method for verifying the performance of a liquid cooling unit. Background Art

[0002] At present, with the rise of the new energy industry, the development of containerized energy storage systems has become a top priority. Conventional containerized energy storage systems are mainly integrated with packs, electrical cabinets, battery management systems, thermal management systems, and fire protection systems. They have the characteristics of short integration cycle, high integration, and wide application scenarios. However, with the rapid development and application of the energy storage industry, fire accidents in containerized energy storage systems often occur. The reason is that there are electrical energy conversion and chemical processes in the operation of the energy storage system, which will generate a lot of heat. If the heat cannot be dissipated in time and effectively, the high temperature will accelerate the internal chemical reaction of the battery, forming a vicious cycle, which will lead to thermal runaway and cause fire accidents. According to the investigation of the cause of the fire accident, the cause of the fire mostly started from the runaway of battery thermal management, and the liquid cooling unit under the thermal management system played a vital role in cooling the entire containerized energy storage system and battery cells. Therefore, for the preliminary work of containerized energy storage system integration, the performance of the liquid cooling unit has become a key indicator. How to determine the liquid cooling unit is a technical problem that needs to be solved urgently. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a method for verifying the performance comparison of a liquid cooling unit, wherein the liquid cooling unit is applied to a containerized energy storage system, and the liquid cooling unit comprises: a first liquid cooling unit and a second liquid cooling unit, and the method comprises:

[0004] A first containerized energy storage system equipped with the first liquid cooling unit and a second containerized energy storage system equipped with the second liquid cooling unit are respectively made to meet the test conditions; under the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit are respectively made to execute the first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy correspondingly, so as to obtain a stack-level battery cell temperature data set and a liquid cooling unit outlet water temperature data set; according to the stack-level battery cell temperature data set and the liquid cooling unit outlet water temperature data set, the refrigeration performance of the first liquid cooling unit and the second liquid cooling unit are compared to determine the optimal liquid cooling unit; wherein, the first charge and discharge test condition is the same as the second charge and discharge test condition, and the charge and discharge rate in the first charge and discharge test condition is less than the charge and discharge rate in the third charge and discharge test condition; the maximum temperature of the battery cell required for starting the first liquid cooling strategy is higher than that of the second liquid cooling strategy, and the first liquid cooling strategy is the same as the third liquid cooling strategy.

[0005] In the method as described above, optionally, the test condition is: discharging at a first charge and discharge rate until the voltage of any battery cell in the first containerized energy storage system and the second containerized energy storage system reaches a first discharge cut-off voltage; the temperature of any battery cell in the first containerized energy storage system and the second containerized energy storage system is within a first temperature range, and the temperature difference between any two battery cells is not greater than a second temperature threshold.

[0006] In the method as described above, optionally, the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition all include: multiple charge and discharge cycle processes, and any of the charge and discharge cycle processes sequentially include: a charging step, a rest step, a discharging step, and the rest step; the charging step is: charging at a charge and discharge rate corresponding to each charge and discharge test condition until the voltage of any battery cell in the first containerized energy storage system and the second containerized energy storage system reaches a first charge cut-off voltage and stops; the rest step is: resting for a first time; the discharging step is: discharging at a charge and discharge rate corresponding to each charge and discharge test condition until the voltage of any battery cell in the first containerized energy storage system and the second containerized energy storage system reaches a first discharge cut-off voltage and stops.

[0007] In the method described above, optionally, the charge and discharge ratio corresponding to the first charge and discharge test condition is 0.5P, and the charge and discharge ratio corresponding to the third charge and discharge test condition is in the range of greater than 0.5P and less than 0.58P.

[0008] In the method described above, optionally, the first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy all include: a cooling mode, a shutdown mode and a self-circulation mode, the maximum temperature of the battery cell required for starting the cooling mode and the shutdown mode of the first liquid cooling strategy is higher than that of the second liquid cooling strategy, and the first liquid cooling strategy is the same as the third liquid cooling strategy.

[0009] In the method described above, optionally, the starting condition of the refrigeration mode of the first liquid cooling strategy is: the maximum temperature of the battery cell in the first containerized energy storage system and the second containerized energy storage system is not less than the third temperature threshold; the starting condition of the shutdown mode of the first liquid cooling strategy is: the maximum temperature of the battery cell in the first containerized energy storage system and the second containerized energy storage system is not greater than the fourth temperature threshold and the temperature difference of the battery cell is not greater than the fifth temperature threshold; the starting condition of the self-circulation mode of the first liquid cooling strategy is: the maximum temperature of the battery cell in the first containerized energy storage system and the second containerized energy storage system is not greater than The fourth temperature threshold and the temperature difference of the battery cell is greater than the fifth temperature threshold; in the self-circulation mode, when the temperature difference of the battery cell is not greater than the second temperature threshold, the liquid cooling unit shuts down; the start-up condition of the refrigeration mode of the second liquid cooling strategy is: the maximum temperature of the battery cell in the first container energy storage system and the second container energy storage system is not less than the sixth temperature threshold, and the sixth temperature threshold is greater than the third temperature threshold; the start-up condition of the shutdown mode of the second liquid cooling strategy is: the maximum temperature of the battery cell in the first container energy storage system and the second container energy storage system is not greater than the seventh temperature threshold and the temperature difference of the battery cell is not greater than the fifth temperature threshold.

[0010] In the method described above, optionally, the third temperature threshold is within the first temperature range, the fourth temperature threshold is less than the third temperature threshold and is not within the first temperature range, the fifth temperature threshold is greater than the second temperature threshold, and the seventh temperature threshold is less than the sixth temperature threshold and greater than the third temperature threshold.

[0011] In the method described above, optionally, the first temperature threshold range is 25℃±2℃, the second temperature threshold is 2℃, the third temperature threshold is 25℃, the fourth temperature threshold is 20℃, the fifth temperature threshold is 5℃, the sixth temperature threshold is 32℃, and the seventh temperature threshold is 28℃.

[0012] In the method described above, optionally, the first liquid cooling unit and the second liquid cooling unit are of different brands but have the same or similar specifications; the first containerized energy storage system and the second containerized energy storage system are the same containerized energy storage system.

[0013] In the method as described above, optionally, comparing the refrigeration performance of the first liquid cooling unit and the second liquid cooling unit according to the stack-level battery core temperature data set and the liquid cooling unit outlet water temperature data set to determine the optimal liquid cooling unit includes:

[0014] The stack-level battery cell temperature data set includes: a first group of stack-level battery cell temperature data corresponding to the first charge and discharge test condition, a second group of stack-level battery cell temperature data corresponding to the second charge and discharge test condition, and a third group of stack-level battery cell temperature data corresponding to the third charge and discharge test condition, each group of stack-level battery cell temperature data has: a maximum temperature of a stack cell and a maximum temperature difference of a stack cell; the liquid cooling unit outlet water temperature data set includes: a first group of liquid cooling unit outlet water temperatures corresponding to the first charge and discharge test condition, a second group of liquid cooling unit outlet water temperatures corresponding to the second charge and discharge test condition, and a third group of liquid cooling unit outlet water temperatures corresponding to the third charge and discharge test condition; under the first charge and discharge test condition, the second charge and discharge test condition, and the third charge and discharge test condition, the optimal liquid cooling unit among the first liquid cooling unit and the second liquid cooling unit has the lowest maximum temperature of a stack cell, the maximum temperature difference of a stack cell, and the lowest outlet water temperature of a liquid cooling unit.

[0015] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0016] By making the first containerized energy storage system equipped with the first liquid cooling unit and the second containerized energy storage system equipped with the second liquid cooling unit meet the test conditions respectively; under the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit respectively execute the first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy respectively, to obtain the stack-level battery cell temperature data set and the liquid cooling unit outlet water temperature data set; according to the stack-level battery cell temperature data set and the liquid cooling unit The water outlet temperature data set is used to compare the refrigeration performance of the first liquid cooling unit and the second liquid cooling unit to determine the optimal liquid cooling unit; the first charge and discharge test condition is the same as the second charge and discharge test condition, and the charge and discharge rate in the first charge and discharge test condition is less than the charge and discharge rate in the third charge and discharge test condition; the maximum temperature of the battery cell required to start the first liquid cooling strategy is higher than that of the second liquid cooling strategy, and the first liquid cooling strategy is the same as the third liquid cooling strategy, which can verify the performance of the two liquid cooling units and determine the optimal liquid cooling unit, which is conducive to optimizing the configuration of the liquid cooling unit of the energy storage container system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a comparative test method for verifying the performance of a liquid cooling unit provided by an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the maximum temperature of a stack cell in a first group of stack-level battery core temperature data corresponding to a first liquid cooling unit provided in an embodiment of the present invention;

[0019] Figure 3A schematic diagram of the maximum temperature of a stack cell in a first group of stack-level battery core temperature data corresponding to a second liquid cooling unit provided in an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of the maximum temperature of a stack cell in a second group of stack-level battery core temperature data corresponding to a first liquid cooling unit provided in an embodiment of the present invention;

[0021] Figure 5 A schematic diagram of the maximum temperature of a stack cell in a second group of stack-level battery core temperature data corresponding to a second liquid cooling unit provided in an embodiment of the present invention;

[0022] Figure 6 A schematic diagram of the maximum temperature of a stack cell in a third group of stack-level battery core temperature data corresponding to a first liquid cooling unit provided in an embodiment of the present invention;

[0023] Figure 7 A schematic diagram of the maximum temperature of a stack cell in a third group of stack-level battery core temperature data corresponding to a second liquid cooling unit provided in an embodiment of the present invention;

[0024] Figure 8 A schematic diagram of a maximum temperature difference of a stack-level battery cell in a first group of stack-level battery cell temperature data corresponding to a first liquid cooling unit and a second liquid cooling unit provided in an embodiment of the present invention;

[0025] Fig. 9 A schematic diagram of a maximum temperature difference of a stack-level battery cell in a second group of stack-level battery cell temperature data corresponding to a first liquid cooling unit and a second liquid cooling unit provided in an embodiment of the present invention;

[0026] Fig.10 A schematic diagram of a maximum temperature difference of a stack-level battery cell in a third group of stack-level battery cell temperature data corresponding to a first liquid cooling unit and a second liquid cooling unit provided in an embodiment of the present invention;

[0027] Fig.11 A schematic diagram of a first group of liquid cooling unit outlet water temperature data corresponding to a first liquid cooling unit provided in an embodiment of the present invention;

[0028] Fig.12 A schematic diagram of water outlet temperature data of a first group of liquid cooling units corresponding to a second liquid cooling unit provided in an embodiment of the present invention;

[0029] Fig.13 A schematic diagram of outlet water temperature data of a second group of liquid cooling units corresponding to a first liquid cooling unit provided in an embodiment of the present invention;

[0030] Fig.14 A schematic diagram of a second group of liquid cooling unit outlet water temperature data corresponding to a second liquid cooling unit provided in an embodiment of the present invention;

[0031] Fig.15 A schematic diagram of a third group of liquid cooling unit outlet water temperature data corresponding to the first liquid cooling unit provided in an embodiment of the present invention;

[0032] Fig.16 A schematic diagram of a third group of liquid cooling unit outlet water temperature data corresponding to a second liquid cooling unit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0035] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0036] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if determining" or "if monitoring (stated condition or event)" may be interpreted as "when determining" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0037] It should be noted that the limitations such as "first" and "second" involved in the embodiments of the present invention do not have limitations in terms of size, order and quantity, and are only used to distinguish them in name. For example, "first preset voltage threshold" and "second preset voltage threshold" are used to distinguish two different preset voltage thresholds, and "first preset time", "second preset time" and "third preset time" are used to distinguish three different preset time values.

[0038] See also Figure 1 An embodiment of the present invention provides a comparative test method for verifying the performance of a liquid cooling unit. The liquid cooling unit is applied to a containerized energy storage system. The liquid cooling unit includes: a first liquid cooling unit and a second liquid cooling unit. The first liquid cooling unit and the second liquid cooling unit are of different brands, but have the same or similar specifications. When the specifications are similar, that is, the difference between the specification parameters is within the preset requirement range, the specification parameters may be the cooling capacity, and in other embodiments, may also be the size. The brand corresponding to the first liquid cooling unit may be referred to as brand 1, and the brand corresponding to the second liquid cooling unit may be referred to as brand 2.

[0039] The method comprises the following steps:

[0040] Step 101 : Make a first containerized energy storage system equipped with a first liquid cooling unit and a second containerized energy storage system equipped with a second liquid cooling unit meet test conditions respectively.

[0041] When applying this method, a containerized energy storage system can be deployed, that is, the first liquid cooling unit and the second liquid cooling unit share a containerized energy storage system. After the containerized energy storage system equipped with the first liquid cooling unit is tested, it is disassembled and the second liquid cooling unit is installed, and then tested again. In order to better distinguish and describe this method, the containerized energy storage system equipped with the first liquid cooling unit is referred to as the first containerized energy storage system or the first energy storage container system; the containerized energy storage system equipped with the second liquid cooling unit is referred to as the second containerized energy storage system or the second energy storage container system. The purpose of this step is to make each containerized energy storage system meet the test conditions, and after the test conditions are met, the test can be started. In other embodiments, two identical containerized energy storage systems can also be deployed, one containerized energy storage system independently configured with the first liquid cooling unit, and the other containerized energy storage system independently configured with the second liquid cooling unit. It should be noted that in order to improve the consistency of the test, it is preferred to deploy a containerized energy storage system. The structure of the containerized energy storage system is preferably capable of completing the present test method, and its structure may be the same as that of a conventional containerized energy storage system, such as also including: a fire protection system. In other embodiments, a fire protection system may also not be included, and this embodiment does not limit this.

[0042] First, each containerized energy storage system is discharged. Specifically, the discharge is stopped at the first charge-discharge rate until the voltage of any battery cell in the first containerized energy storage system reaches the first discharge cut-off voltage; the discharge is stopped at the first charge-discharge rate until the voltage of any battery cell in the second containerized energy storage system reaches the first discharge cut-off voltage. The first charge-discharge rate is preferably 0.5P, and the first discharge cut-off voltage is preferably 2.5V. This embodiment does not limit this, and the values ​​of the two can be adjusted according to specific requirements.

[0043] Then perform the temperature balancing operation so that any cell temperature in each containerized energy storage system is within the first temperature range, and the cell temperature difference is not greater than the second temperature threshold, that is, any cell temperature in the first containerized energy storage system is within the first temperature range, and the cell temperature difference is not greater than the second temperature threshold; any cell temperature in the second containerized energy storage system is within the first temperature range, and the cell temperature difference is not greater than the second temperature threshold. The cell temperature difference refers to the difference between any two cell temperatures in the containerized energy storage system. The first temperature range is preferably: 25°C ± 2°C, and the second temperature threshold is preferably: 2°C. This embodiment does not limit this, and the values ​​of the two can be adjusted according to specific requirements. The temperature balancing operation can be achieved by manually controlling the liquid cooling unit, which is different from the first liquid cooling strategy, the second liquid cooling strategy, and the third liquid cooling strategy described below. The three liquid cooling strategies are achieved by automatically controlling the liquid cooling unit.

[0044] Step 102, under the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit respectively execute the first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy correspondingly, to obtain a stack-level battery cell temperature data set and a liquid cooling unit outlet water temperature data set.

[0045] Three charge and discharge test conditions are set, namely: the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition. Any of all the charge and discharge test conditions includes: multiple charge and discharge cycle processes, the number of cycles of the process can be 3-5 times, such as 3 times, 4 times, 5 times, and in other embodiments, it can also be other times, which is not limited in this embodiment. Each charge and discharge cycle process includes: a charging step, a rest step, a discharge step, and a rest step in sequence.

[0046] Specifically: Charging step: charging at a charge and discharge rate corresponding to the charge and discharge test condition until the voltage of any battery cell in the first containerized energy storage system and the second containerized energy storage system reaches the first charge cut-off voltage and stops. The first charge cut-off voltage is preferably: 3.65V, which is not specifically limited in this embodiment and can also be other values. Standing step: standing for a first time, and the first time is preferably: 1h. Discharging step: discharging at a charge and discharge rate corresponding to the charge and discharge test condition until the voltage of any battery cell in the first containerized energy storage system and the second containerized energy storage system reaches the first discharge cut-off voltage and stops.

[0047] The first charge and discharge test condition is the same as the second charge and discharge test condition, and the charge and discharge rate in the first charge and discharge test condition is less than the charge and discharge rate in the third charge and discharge test condition. Specifically, when the charge and discharge test condition is the first charge and discharge test condition or the second charge and discharge test condition, the charge and discharge rates corresponding to the two conditions are the same, both of which are: the first charge and discharge rate. When the charge and discharge test condition is the third charge and discharge test condition, the charge and discharge rate corresponding to the condition is greater than the first charge and discharge rate, and its value range can be: greater than 0.5P and less than 0.58P, such as 0.51P, 0.52P, 0.53P, 0.54P, 0.55P, 0.56P, 0.57P.

[0048] Three liquid cooling strategies are set, namely the first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy, corresponding to three charging and discharging test conditions, that is, the first charging and discharging test condition corresponds to the first liquid cooling strategy, under the first charging and discharging test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit respectively execute the first liquid cooling strategy; the second charging and discharging test condition corresponds to the second liquid cooling strategy, under the second charging and discharging test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit respectively execute the second liquid cooling strategy; the third charging and discharging test condition corresponds to the third liquid cooling strategy, under the third charging and discharging test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit respectively execute the third liquid cooling strategy. The maximum cell temperature required for starting the first liquid cooling strategy is higher than that of the second liquid cooling strategy, that is, when the maximum cell temperature of all cell cells in the containerized energy storage system reaches a certain value, the first liquid cooling strategy is started; when the maximum cell temperature of all cell cells in the containerized energy storage system reaches another value, the second liquid cooling strategy is started, and the maximum cell temperature when the first liquid cooling strategy is started is higher than the maximum cell temperature when the second liquid cooling strategy is started. The first liquid cooling strategy is the same as the third liquid cooling strategy. It should be noted that when the three liquid cooling strategies are executed separately, it is necessary to set the water outlet temperature of the liquid cooling unit (that is, the target temperature or the refrigeration set temperature), preferably, it is set to 18°C.

[0049] Any of the three liquid cooling strategies includes: cooling mode, shutdown mode and self-circulation mode. The maximum cell temperature required for starting the cooling mode and shutdown mode of the first liquid cooling strategy is higher than that of the second liquid cooling strategy. The cooling mode means that the liquid cooling unit is turned on and is in the cooling working state; the shutdown mode means that the liquid cooling unit is turned on but is not in the working state; the self-circulation mode means that the liquid cooling unit puts the coolant in the liquid cooling pipeline into the self-circulation state, that is, it does not heat or cool, and it is not in the shutdown state.

[0050] The starting condition of the refrigeration mode of the first liquid cooling strategy: when the highest temperature of the battery cell in the containerized energy storage system is not less than the third temperature threshold, the refrigeration mode is started, that is, the liquid cooling unit starts refrigeration, and the third temperature threshold belongs to the first temperature range, preferably: 25°C. The starting condition of the shutdown mode of the first liquid cooling strategy: when the highest temperature of the battery cell in the containerized energy storage system is not greater than the fourth temperature threshold and the temperature difference of the battery cell is not greater than the fifth temperature threshold, the shutdown mode is started, that is, the liquid cooling unit is shut down, the fourth temperature threshold is less than the third temperature threshold, preferably, the fourth temperature threshold is less than the third temperature threshold and is not within the first temperature range, preferably: 20°C; the fifth temperature threshold is greater than the second temperature threshold, preferably 5°C. The starting condition of the self-circulation mode of the first liquid cooling strategy: when the highest temperature of the battery cell in the containerized energy storage system is not greater than the fourth temperature threshold and the temperature difference of the battery cell is greater than the fifth temperature threshold, the self-circulation mode is started, that is, the liquid cooling unit starts self-circulation. In this mode, when the temperature difference of the battery cell is not greater than the second temperature threshold, the liquid cooling unit is shut down. That is to say, preferably, under the first liquid cooling strategy, the maximum temperature is ≥25°C, refrigeration is turned on, and the water temperature at the outlet of the liquid cooling unit (or the outlet temperature) is: 18°C; when the maximum temperature is ≤20°C and the temperature difference is ≤5°C, the liquid cooling unit is shut down; when the maximum temperature is ≤20°C and the temperature difference is >5°C, refrigeration is stopped, self-circulation is turned on, and the liquid cooling unit is shut down when the temperature difference is ≤2°C.

[0051] The starting conditions of the refrigeration mode of the second liquid cooling strategy: when the maximum temperature of the battery cell in the containerized energy storage system is not less than the sixth temperature threshold, the refrigeration mode is started, that is, the liquid cooling unit starts refrigeration, and the sixth temperature threshold is greater than the third temperature threshold. Preferably, the sixth temperature threshold is greater than the third temperature threshold and is not within the first temperature range, preferably: 32°C. The starting conditions of the shutdown mode of the second liquid cooling strategy: when the maximum temperature of the battery cell in the containerized energy storage system is not greater than the seventh temperature threshold and the temperature difference of the battery cell is not greater than the fifth temperature threshold, the shutdown mode is started, that is, the liquid cooling unit is shut down, and the seventh temperature threshold is less than the sixth temperature threshold and greater than the third temperature threshold, preferably: 28°C. The starting conditions of the self-circulation mode of the second liquid cooling strategy are the same as the starting conditions of the self-circulation mode of the first liquid cooling strategy. That is to say, preferably, under the second liquid cooling strategy, when the maximum temperature is ≥32°C, refrigeration is turned on, and the water temperature at the water outlet of the liquid cooling unit is 18°C; when the maximum temperature is ≤28°C and the temperature difference is ≤5°C, the liquid cooling unit is shut down; when the maximum temperature is ≤20°C and the temperature difference is >5°C, refrigeration is stopped, self-circulation is turned on, and the liquid cooling unit is shut down when the temperature difference is ≤2°C.

[0052] When this method is applied, the power consumption of the first liquid cooling unit and the second liquid cooling unit during the test process can also be recorded respectively. The first charge and discharge test condition can be called: conventional charge and discharge condition, the second charge and discharge test condition can be called: a condition of raising the battery cell temperature, and the second charge and discharge test condition can be called: a condition of raising the charge and discharge rate.

[0053] Under the first charge-discharge test condition and the first liquid cooling strategy, the first liquid cooling unit and the second liquid cooling unit are tested respectively to obtain the first group of stack-level battery core temperature data and the first group of liquid cooling unit outlet water temperature data; under the second test charge-discharge test condition and the second liquid cooling strategy, the first liquid cooling unit and the second liquid cooling unit are tested respectively to obtain the second group of stack-level battery core temperature data and the second group of liquid cooling unit outlet water temperature data; under the third test charge-discharge test condition and the third liquid cooling strategy, the first liquid cooling unit and the second liquid cooling unit are tested respectively to obtain the third group of stack-level battery core temperature data and the third group of liquid cooling unit outlet water temperature data. The first group of stack-level battery core temperature data, the second group of stack-level battery core temperature data and the third group of stack-level battery core temperature data are collected to form a stack-level battery core temperature data set; the first group of liquid cooling unit outlet water temperature data, the second group of liquid cooling unit outlet water temperature data and the third group of liquid cooling unit outlet water temperature data are collected to form a liquid cooling unit outlet water temperature data set. It should be noted that: the stack-level cell temperature data refers to: the temperature data of all cell monomers in the containerized energy storage system, which includes: the maximum temperature of the stack monomer and the maximum temperature difference of the stack-level cell. The maximum temperature of the stack monomer refers to: the highest temperature of all cell monomer temperatures in the containerized energy storage system, which has: the maximum temperature of the stack monomer during charging and the maximum temperature of the stack monomer during discharging, that is, the highest temperature of all cell monomer temperatures in the containerized energy storage system during charging and the highest temperature of all cell monomer temperatures in the containerized energy storage system during discharging. The maximum temperature difference of the stack-level cell refers to: the maximum temperature difference of any two cell monomer temperatures among all cell monomer temperatures in the containerized energy storage system, which is the maximum temperature difference of the stack-level cell during charging and discharging, that is, the maximum temperature difference of any two cell monomer temperatures among all cell monomer temperatures in the containerized energy storage system during charging and discharging. The stack-level cell temperature data can be obtained by measuring the BMS (Battery Management System) of the containerized energy storage system. The outlet water temperature data of the liquid cooling unit refers to: the average temperature of the water temperature at the outlet of the liquid cooling unit, that is, the average outlet water temperature. The outlet water temperature data of the liquid cooling unit can be obtained by measuring the liquid cooling unit.

[0054] Step 103 , comparing the refrigeration performance of the first liquid cooling unit and the second liquid cooling unit according to the stack-level battery core temperature data set and the liquid cooling unit outlet water temperature data set, and determining the optimal liquid cooling unit.

[0055] The best liquid cooling unit among the best liquid cooling units in the first liquid cooling unit and the second liquid cooling unit has the lowest maximum temperature of the stack monomer, the maximum temperature difference of the stack-level battery cells, and the outlet water temperature of the liquid cooling unit. That is, under the first liquid cooling strategy, the second liquid cooling strategy, and the third liquid cooling strategy, the maximum temperature of the stack monomer, the maximum temperature difference of the stack-level battery cells, and the outlet water temperature of the liquid cooling unit of the best liquid cooling unit are not higher than the maximum temperature of the stack monomer, the maximum temperature difference of the stack-level battery cells, and the outlet water temperature of the liquid cooling unit of the other liquid cooling unit.

[0056] Specifically, by executing step 102, the maximum temperature of the stack cell in the first group of stack-level battery cell temperature data can be obtained:

[0057] Brand 1: The maximum temperature of the stack monomer during charging is 35°C, and the maximum temperature of the stack monomer during discharging is 35°C. Figure 2 As shown by the yellow line in the figure; Brand 2: The maximum temperature of the stack monomer during charging is 34°C, and the maximum temperature of the stack monomer during discharging is 34°C. Figure 3 As shown by the red line in the figure. Conclusion: Brand 2 has better cooling performance than Brand 1.

[0058] The maximum temperature of the stack cell in the second set of stack-level cell temperature data can also be obtained:

[0059] Brand 1: The maximum temperature of the stack monomer during charging is 38°C, and the maximum temperature of the stack monomer during discharging is 37°C. Figure 4 As shown by the red line in the figure; Brand 2: The maximum temperature of the stack monomer during charging is 37°C, and the maximum temperature of the stack monomer during discharging is 36°C. Figure 5 As shown by the red line in the figure; Conclusion: The refrigeration performance of brand 2 is better than that of brand 1.

[0060] You can also get: The maximum temperature of the stack cell in the third set of stack-level battery temperature data:

[0061] Brand 1: The maximum temperature of the stack monomer during charging is 37°C, and the maximum temperature of the stack monomer during discharging is 38°C. Figure 6 As shown by the red line in the figure; Brand 2: The maximum temperature of the stack monomer during charging is 36°C, and the maximum temperature of the stack monomer during discharging is 37°C. Figure 7 As shown by the red line in the figure; Conclusion: The refrigeration performance of brand 2 is better than that of brand 1.

[0062] You can also get: the maximum temperature difference of the stack-level battery cells in the first set of stack-level battery cell temperature data:

[0063] Brand 1: The maximum temperature difference of the stack-level battery cells during the charging and discharging process is 6°C. Figure 8 As shown by the blue line in the figure; Brand 2: The maximum temperature difference of the stack-level battery cells during the charging and discharging process is 5°C. Figure 8 As shown by the orange line in the figure; Conclusion: Brand 2 has better refrigeration performance than Brand 1.

[0064] You can also get: the maximum temperature difference of the stack-level battery cells in the second set of stack-level battery cell temperature data:

[0065] Brand 1: The maximum temperature difference of the stack-level battery cells during the charging and discharging process is 6°C. Fig. 9 As shown by the blue line in the figure; Brand 2: The maximum temperature difference of the stack-level battery cells during the charging and discharging process is 5°C. Fig. 9 As shown by the orange line in the figure; Conclusion: Brand 2 has better refrigeration performance than Brand 1.

[0066] You can also get: The maximum temperature difference of the stack-level battery cells in the third set of stack-level battery cell temperature data:

[0067] Brand 1: The maximum temperature difference of the stack-level battery cells during the charging and discharging process is 6°C. Fig.10 As shown by the blue line in the figure; Brand 2: The maximum temperature difference of the stack-level battery cells during the charging and discharging process is 5°C. Fig.10 As shown by the orange line in the figure; Conclusion: Brand 2 has better refrigeration performance than Brand 1.

[0068] You can also get: The outlet water temperature of the first group of liquid cooling units:

[0069] Brand 1: The outlet water temperature data is for the discharge and charging process. The outlet water temperature of the liquid cooling unit is maintained at less than 18°C, and the average outlet water temperature is 20°C. Fig.11 The orange line in the figure indicates the average outlet water temperature. Brand 2: The outlet water temperature data is the outlet water temperature of the liquid cooling unit during the discharge and charging processes, which is maintained below 18°C, and the average outlet water temperature is 17.36°C. Fig.12 As shown by the orange line representing the average water outlet temperature; Conclusion: The cooling performance of brand 2 is better than that of brand 1.

[0070] You can also get: The outlet water temperature of the second liquid cooling unit:

[0071] Brand 1: The outlet water temperature data is for the discharge and charging process. The outlet water temperature of the liquid cooling unit is maintained at ≥18°C, and the average outlet water temperature is 22.4°C. Fig.13 The orange line in the figure indicates the average outlet water temperature. Brand 2: The outlet water temperature data is for the discharge and charging processes. The outlet water temperature of the liquid cooling unit is maintained at ≥18°C, and the average outlet water temperature is 19.2°C. Fig.14 As shown by the orange line representing the average water outlet temperature; Conclusion: The cooling performance of brand 2 is better than that of brand 1.

[0072] You can also get: The outlet water temperature of the third group of liquid cooling units:

[0073] Brand 1: The outlet water temperature data is for the discharge and charging process. The outlet water temperature of the liquid cooling unit is maintained at ≥18°C, and the average outlet water temperature is 20°C. Fig.15The gray line in the figure indicates the average outlet water temperature; Brand 2: The outlet water temperature data is the outlet water temperature of the liquid cooling unit during the discharge and charging processes, which is maintained at ≥18°C, and the average outlet water temperature is 18.2°C. Fig.16 As shown by the orange line representing the average water outlet temperature; Conclusion: The cooling performance of brand 2 is better than that of brand 1.

[0074] The test data is obtained by testing in a comparative manner. Specifically, the three aspects of the maximum temperature of the stack cell, the maximum temperature difference of the stack-level battery cell, and the outlet water temperature of the liquid cooling unit are compared to determine which of the two liquid cooling units has the best performance, that is, to determine the optimal liquid cooling unit. The lower the maximum temperature of the stack cell, the higher the performance of the liquid cooling unit; the smaller the maximum temperature difference of the stack-level battery cell, the higher the performance of the liquid cooling unit; the lower the outlet water temperature of the liquid cooling unit, the higher the performance of the liquid cooling unit. In other embodiments, one more aspect can be added: the minimum temperature of the stack cell. Accordingly, the lower the minimum temperature of the stack cell, the higher the performance of the liquid cooling unit.

[0075] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for comparing the performance of a liquid cooling unit, wherein the liquid cooling unit is applied to a containerized energy storage system, characterized in that: The liquid cooling unit comprises: a first liquid cooling unit and a second liquid cooling unit, and the method comprises: Make a first containerized energy storage system equipped with the first liquid cooling unit and a second containerized energy storage system equipped with the second liquid cooling unit meet test conditions respectively; Under the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition, each containerized energy storage system is tested respectively, and during the test, the first liquid cooling unit and the second liquid cooling unit are respectively made to execute the first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy correspondingly, to obtain a stack-level battery cell temperature data set and a liquid cooling unit outlet water temperature data set; According to the stack-level battery core temperature data set and the liquid cooling unit outlet water temperature data set, comparing the refrigeration performance of the first liquid cooling unit and the second liquid cooling unit, and determining the optimal liquid cooling unit; Wherein, the first charge and discharge test condition is the same as the second charge and discharge test condition, and the charge and discharge rate in the first charge and discharge test condition is less than the charge and discharge rate in the third charge and discharge test condition; The maximum cell temperature required for starting the first liquid cooling strategy is higher than that of the second liquid cooling strategy, and the first liquid cooling strategy is the same as the third liquid cooling strategy.

2. The method according to claim 1, characterized in that The test condition is: discharging at a first charge-discharge rate until the voltage of any cell in the first containerized energy storage system and the second containerized energy storage system reaches a first discharge cut-off voltage; The temperature of any battery cell in the first containerized energy storage system and the second containerized energy storage system is within a first temperature range, and the temperature difference between any two battery cells is not greater than a second temperature threshold.

3. The method according to claim 1, characterized in that The first charge-discharge test condition, the second charge-discharge test condition and the third charge-discharge test condition all include: multiple charge-discharge cycle processes, and any of the charge-discharge cycle processes sequentially include: a charging step, a resting step, a discharging step, and the resting step; The charging process step is: charging at a charge and discharge rate corresponding to each charge and discharge test condition until the voltage of any cell in the first containerized energy storage system and the second containerized energy storage system reaches a first charging cut-off voltage and stops; The static step is as follows: static for a first time period; The discharging step is: discharging at a charge and discharge rate corresponding to each charge and discharge test condition until the voltage of any battery cell in the first containerized energy storage system and the second containerized energy storage system reaches a first discharge cut-off voltage and stops.

4. The method according to claim 3, characterized in that The charge and discharge ratio corresponding to the first charge and discharge test condition is 0.5P, and the charge and discharge ratio corresponding to the third charge and discharge test condition is in the range of greater than 0.5P and less than 0.58P.

5. The method according to claim 2, characterized in that: The first liquid cooling strategy, the second liquid cooling strategy and the third liquid cooling strategy all include: a cooling mode, a shutdown mode and a self-circulation mode. The maximum temperature of the battery cell required to start the cooling mode and the shutdown mode of the first liquid cooling strategy is higher than that of the second liquid cooling strategy. The first liquid cooling strategy is the same as the third liquid cooling strategy.

6. The method according to claim 5, characterized in that The start-up condition of the cooling mode of the first liquid cooling strategy is: the maximum temperature of the battery cells in the first containerized energy storage system and the second containerized energy storage system is not less than a third temperature threshold; The start condition of the shutdown mode of the first liquid cooling strategy is: the maximum temperature of the battery cells in the first containerized energy storage system and the second containerized energy storage system is not greater than the fourth temperature threshold and the temperature difference of the battery cells is not greater than the fifth temperature threshold; The start-up condition of the self-circulation mode of the first liquid cooling strategy is: the maximum temperature of the battery cells in the first containerized energy storage system and the second containerized energy storage system is not greater than the fourth temperature threshold and the temperature difference of the battery cells is greater than the fifth temperature threshold; in the self-circulation mode, when the temperature difference of the battery cells is not greater than the second temperature threshold, the liquid cooling unit is shut down; The start-up condition of the cooling mode of the second liquid cooling strategy is: the maximum temperature of the battery cells in the first containerized energy storage system and the second containerized energy storage system is not less than the sixth temperature threshold, and the sixth temperature threshold is greater than the third temperature threshold; The start-up condition of the shutdown mode of the second liquid cooling strategy is: the maximum temperature of the battery cells in the first containerized energy storage system and the second containerized energy storage system is not greater than the seventh temperature threshold and the temperature difference of the battery cells is not greater than the fifth temperature threshold.

7. The method according to claim 6, characterized in that The third temperature threshold is within the first temperature range, the fourth temperature threshold is less than the third temperature threshold and is not within the first temperature range, the fifth temperature threshold is greater than the second temperature threshold, and the seventh temperature threshold is less than the sixth temperature threshold and greater than the third temperature threshold.

8. The method according to claim 7, characterized in that The first temperature threshold range is 25°C±2°C, the second temperature threshold is 2°C, the third temperature threshold is 25°C, the fourth temperature threshold is 20°C, the fifth temperature threshold is 5°C, the sixth temperature threshold is 32°C, and the seventh temperature threshold is 28°C.

9. The method according to claim 1, characterized in that: The first liquid cooling unit and the second liquid cooling unit have different brands but the same or similar specifications; The first containerized energy storage system and the second containerized energy storage system are the same containerized energy storage system.

10. The method according to claim 1, characterized in that The comparing the refrigeration performance of the first liquid cooling unit and the second liquid cooling unit according to the stack-level battery core temperature data set and the liquid cooling unit outlet water temperature data set to determine the optimal liquid cooling unit includes: The stack-level battery cell temperature data set includes: a first group of stack-level battery cell temperature data corresponding to a first charge-discharge test condition, a second group of stack-level battery cell temperature data corresponding to a second charge-discharge test condition, and a third group of stack-level battery cell temperature data corresponding to a third charge-discharge test condition, each group of stack-level battery cell temperature data having: a maximum temperature of a stack cell and a maximum temperature difference of a stack-level battery cell; The liquid cooling unit outlet water temperature data set includes: a first group of liquid cooling unit outlet water temperatures corresponding to the first charge and discharge test condition, a second group of liquid cooling unit outlet water temperatures corresponding to the second charge and discharge test condition, and a third group of liquid cooling unit outlet water temperatures corresponding to the third charge and discharge test condition; Under the first charge and discharge test condition, the second charge and discharge test condition and the third charge and discharge test condition, the optimal liquid cooling unit between the first liquid cooling unit and the second liquid cooling unit has the lowest stack cell maximum temperature, the stack-level battery cell maximum temperature difference and the liquid cooling unit water outlet temperature.

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