Battery thermal management method, controller and mechanical system

Abstract

The invention provides a battery thermal management method, a controller and a mechanical system. The battery thermal management method comprises the following steps: acquiring the environment temperature and the internal temperature of each branch in a plurality of branches which are connected in parallel and are respectively provided with a battery pack of a battery system, and determining the external and internal temperature difference of each branch based on the environment temperature and the internal temperature of each branch; and under the condition that the external and internal temperature difference of the branch is greater than a temperature difference threshold value, temperature regulation and control are performed on the branch, so that the branch meets preset conditions, and the preset conditions comprise that the external and internal temperature difference of the branch is smaller than or equal to a preset temperature difference value and the preset temperature difference value is smaller than or equal to the temperature difference threshold value. In this way, the performance of the battery system including the parallel branches may be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery thermal management, and in particular to a battery thermal management method, a controller and a mechanical system. BACKGROUND

[0002] With the development of the new energy industry, large-tonnage mechanical systems (such as mining trucks, port machinery, engineering machinery, etc.) are accelerating electrification. The power battery system of such mechanical systems usually includes multiple branches in parallel with each other and each having a battery pack to provide greater power to meet higher power demands. Moreover, these parallel branches are usually distributed at different locations such as a vehicle frame and a chassis, are far apart, have large differences in ambient temperature, and have significant differences in environmental thermal interference.

[0003] However, in the related art, when the parallel branches are thermally managed, the differentiated effects of ambient temperature are not effectively considered, which can easily lead to a high temperature difference between the branches, affecting the performance of the battery system.

[0004] The above statements are only used to provide background technical information related to the present application, and do not necessarily constitute the prior art. SUMMARY

[0005] The present application aims to provide a battery thermal management method, a controller and a mechanical system to improve the performance of a battery system including parallel branches.

[0006] To achieve the above-mentioned purpose, the battery thermal management method provided by the present application comprises:

[0007] Collecting the ambient temperature and the internal temperature of each branch of the multiple branches in parallel with each other and each having a battery pack of the battery system, and determining the external-internal temperature difference of each branch based on the ambient temperature and the internal temperature of each branch;

[0008] In the case where the external-internal temperature difference of the branch is greater than a temperature difference threshold, the temperature of the branch is regulated to make the branch meet a preset condition, and the preset condition includes that the external-internal temperature difference of the branch is less than or equal to a preset temperature difference value, and the preset temperature difference value is less than or equal to the temperature difference threshold.

[0009] In some embodiments, collecting the ambient temperature and the internal temperature of each branch of the multiple parallel branches, and determining the external-internal temperature difference of each branch according to the ambient temperature and the internal temperature of each branch comprises:

[0010] Collecting the internal temperature at multiple points and the ambient temperature at multiple points of each branch, and determining the external-internal temperature difference of each branch according to the average ambient temperature and the average internal temperature of each branch;

[0011] The average internal temperature of each branch is an average of internal temperatures of the branch at multiple points, and the maximum internal temperature of each branch is a maximum value of internal temperatures of the branch at multiple points.

[0012] In some embodiments, before collecting the ambient temperatures of the branches at multiple points, the multiple parallel branches are divided into multiple temperature domains according to different ambient thermal characteristics, and branches with the same ambient thermal characteristics are in the same temperature domain, and the same ambient thermal characteristics include the same ambient temperature range; during the collection of the ambient temperatures of the branches at multiple points, the ambient temperatures of the branches at multiple points in each temperature domain are collected, and the ambient temperatures of the branches at multiple points in each temperature domain are taken as the ambient temperatures of the branches at multiple points in each temperature domain.

[0013] In some embodiments, the preset condition further includes:

[0014] The average internal temperature of the branch is less than or equal to a preset average temperature value, wherein the average internal temperature of the branch is an average of internal temperatures of the branch at multiple points; and / or,

[0015] The maximum internal temperature of the branch is less than or equal to a preset high temperature value, wherein the maximum internal temperature of the branch is a maximum value of internal temperatures of the branch at multiple points.

[0016] In some embodiments, the battery thermal management method further includes at least one of:

[0017] In the case where the average internal temperature of the branch exceeds the average temperature threshold, the temperature of the branch is regulated to meet the preset condition, and the preset condition further includes that the average internal temperature of the branch is less than or equal to a preset average temperature value, the preset average temperature value is less than or equal to the average temperature threshold, and the average internal temperature of the branch is an average of internal temperatures of the branch at multiple points.

[0018] In the case where the maximum internal temperature of the branch exceeds the high temperature threshold, the temperature of the branch is regulated to meet the preset condition, and the preset condition further includes that the maximum internal temperature of the branch is less than or equal to a preset high temperature value, the preset high temperature value is less than or equal to the high temperature threshold, and the maximum internal temperature of the branch is a maximum value of internal temperatures of the branch at multiple points.

[0019] In some embodiments, regulating the temperature of the branch includes:

[0020] Adjusting the flow rate of the cooling liquid in the cooling flow path for cooling the branch.

[0021] In some embodiments, adjusting the flow rate of the cooling liquid in the cooling flow path for cooling the branch includes:

[0022] Adjusting the opening degree of a control valve on the cooling flow path for controlling the flow rate of the cooling liquid.

[0023] In some embodiments, the target opening degree of the control valve is determined based on the outside-inside temperature difference of the branch, in the process of adjusting the opening degree of the control valve.

[0024] In some embodiments, the target opening degree of the control valve is determined based on the product of the outside-inside temperature difference of the branch and a coefficient , in the process of determining the target opening degree of the control valve based on the outside-inside temperature difference of the branch.

[0025] In some embodiments, the target opening degree of the control valve is determined based on at least one of the average internal temperature of the branch, the highest internal temperature of the branch, and the base opening degree of the control valve, in addition to the outside-inside temperature difference of the branch, wherein the average internal temperature of the branch is the average of the internal temperatures of the branch at multiple points, and the highest internal temperature of the branch is the maximum of the internal temperatures of the branch at multiple points.

[0026] In some embodiments, the target opening degree of the control valve is determined based on the difference between the average internal temperature of the branch and a target value of the average internal temperature of the branch, in the process of determining the target opening degree of the control valve based on the average internal temperature of the branch; and / or, the target opening degree of the control valve is determined based on the difference between the highest internal temperature of the branch and a target value of the highest internal temperature of the branch, in the process of determining the target opening degree of the control valve based on the highest internal temperature of the branch.

[0027] In some embodiments, the target opening degree of the control valve is determined based on the product of the difference between the average internal temperature of the branch and a target value of the average internal temperature of the branch and a coefficient , in the process of determining the target opening degree of the control valve based on the difference between the average internal temperature of the branch and a target value of the average internal temperature of the branch; and / or, the target opening degree of the control valve is determined based on the product of the difference between the highest internal temperature of the branch and a target value of the highest internal temperature of the branch and a coefficient , in the process of determining the target opening degree of the control valve based on the difference between the highest internal temperature of the branch and a target value of the highest internal temperature of the branch.

[0028] In some embodiments, the target opening degree of the control valve is determined based on the sum of at least one of the product of the difference between the average internal temperature of the branch and a target value of the average internal temperature of the branch and a coefficient , the product of the difference between the highest internal temperature of the branch and a target value of the highest internal temperature of the branch and a coefficient , and the outside-inside temperature difference of the branch and a coefficient .

[0029] In some embodiments, the temperature regulation of the branch is performed for a duration , and if the branch does not meet the preset condition after a time , the temperature regulation of the branch is stopped.

[0030] In some embodiments, is constant; or, is determined based on at least one of an average internal temperature of the branch and a maximum internal temperature of the branch , wherein the average internal temperature of the branch is an average of the internal temperatures of the branch at the plurality of points, and the maximum internal temperature of the branch is a maximum of the internal temperatures of the branch at the plurality of points.

[0031] In some embodiments, when t is determined based on the average internal temperature of the branch, t is determined based on a difference between the average internal temperature of the branch and a target value of the average internal temperature of the branch; and / or, when t is determined based on the maximum internal temperature of the branch, t is determined based on a difference between the maximum internal temperature of the branch and a target value of the maximum internal temperature of the branch.

[0032] In some embodiments, when t is determined based on the difference between the average internal temperature of the branch and the target value of the average internal temperature of the branch, t is determined based on a product of the difference between the average internal temperature of the branch and the target value of the average internal temperature of the branch and a coefficient ; and / or, when t is determined based on the difference between the maximum internal temperature of the branch and the target value of the maximum internal temperature of the branch, t is determined based on a product of the difference between the maximum internal temperature of the branch and the target value of the maximum internal temperature of the branch and a coefficient .

[0033] In some embodiments, t is further determined based on a base time . .

[0034] In some embodiments, t is determined based on at least one of a product of the difference between the average internal temperature of the branch and the target value of the average internal temperature of the branch and a coefficient and a product of the difference between the maximum internal temperature of the branch and the target value of the maximum internal temperature of the branch and a coefficient and the base time . .

[0035] In some embodiments, if the branch does not meet the preset condition after a time , temperature regulation of the branch is stopped, and current distribution among the branches is performed to make the branches meet the preset condition.

[0036] In some embodiments, when the current distribution among the branches is performed, the current of the branch is determined based on at least one of the average internal temperature of the branch and the remaining power; and / or, a PID algorithm is used to perform the current distribution among the branches.

[0037] In some embodiments, when the current of the branch is determined based on at least one of the average internal temperature of the branch and the residual power of the branch, the current of the branch is determined based on at least one of a difference between the average internal temperature of all parallel branches and the average internal temperature of the branch and a difference between the average residual power of all branches and the residual power of the branch.

[0038] In some embodiments, when the current of the branch is determined based on a difference between the average internal temperature of all branches and the average internal temperature of the branch and a difference between the average residual power of all branches and the residual power of the branch, the current of the branch is determined according to the following formula :

[0039]

[0040] wherein, is equal to the total current divided by the number of branches, is the average internal temperature of all branches, is the average internal temperature of the branch, is the average residual power of all branches, is the residual power of the branch, , and are PID parameters.

[0041] In some embodiments, if the preset condition cannot be met by the current distribution among the branches, one of the current limiting, the abnormal branch power-off and the battery system power-off is used to isolate the abnormal branch.

[0042] In some embodiments, the three modes of current limiting, abnormal branch power-off and battery system power-off are used when the fault level of the abnormal branch belongs to the first level fault, the second level fault and the third level fault, respectively, and the abnormal types of the branches corresponding to the first level fault, the second level fault and the third level fault increase in turn.

[0043] In addition, the controller provided by the present application comprises a memory and a processor coupled to the memory, and the processor is configured to execute the battery thermal management method of any one of the embodiments based on the instructions stored in the memory.

[0044] In addition, the mechanical system provided by the present application comprises a battery system, the battery system comprises a plurality of parallel branches, each branch comprises a battery pack comprising a single cell, and the mechanical system further comprises the controller of any one of the embodiments.

[0045] In some embodiments, the battery system further comprises a converter, and the converter is electrically connected between the branch and the load end and / or the charging end.

[0046] The application effectively considers the differentiated influence of the ambient temperature difference between the branches during thermal management of the battery system including the parallel branches, can reduce the temperature difference amplification effect between the parallel branches, improve the consistency between the parallel branches, prolong the life of each branch in the parallel branches, and improve the performance of the battery system.

[0047] Other features and advantages of the application will be apparent from the following detailed description of exemplary embodiments of the application, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings, which are included to provide a further understanding of the application, illustrate exemplary embodiments of the application and together with the description serve to explain the application. In the drawings:

[0049] Figure 1 It is an electrical architecture diagram of the battery system in the embodiments of the application.

[0050] Figure 2 It is a cooperation diagram of the temperature acquisition module, the electrical acquisition module and the branch in the embodiments of the application.

[0051] Figure 3 It is a division diagram of the temperature domain in the embodiments of the application.

[0052] Figure 4 It is a flowchart of the battery thermal management method in the embodiments of the application.

[0053] BRIEF DESCRIPTION OF DRAWINGS

[0054] 10, battery system;

[0055] 1, branch; 21, temperature acquisition module; 22, electrical acquisition module; 3, converter; 4, load end; 5, temperature domain; 51, first temperature domain; 52, second temperature domain; 53, third temperature domain; 6, sunlight; 7, shelter; 8, air flow. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. The described embodiments are only some of the embodiments of the application, not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, and is by no means any limitation on the application and its application or use.

[0057] In the description of the application, the words "first", "second", etc. used to limit parts are only for the convenience of distinguishing the corresponding parts, and have no special meaning unless otherwise stated. Therefore, it cannot be understood as a limitation on the protection scope of the application.

[0058] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0059] In the description of the present application, "a plurality of" means at least two, that is, including two, three or more cases.

[0060] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0061] A large-capacity battery system usually includes a plurality of parallel branches. For example, in some mechanical systems, the battery capacity exceeds 1000kWh, and the number of branches reaches more than 20. Due to the structural limitations of the mechanical system, the plurality of parallel branches are usually distributed at a distance. They face complex working conditions such as large temperature fluctuations and strong vibration impact. In this case, the distance between the branches is far apart, resulting in significant differences in environmental thermal interference, which easily exacerbates the temperature difference amplification effect between the parallel branches. The temperature difference amplification effect between the parallel branches refers to the vicious cycle of "temperature rise increase-internal resistance decrease-shunt increase-temperature rise increase" caused by local temperature difference between the parallel branches, which affects the performance of the battery system. For example, when the battery pack in a certain branch has a sudden temperature rise due to poor ventilation, its internal resistance may be reduced by 15%, the shunt is increased by 20%, and the temperature difference with other branches is expanded by more than 10℃ within 30 minutes, which directly leads to a sharp reduction in the cycle life of the branch.

[0062] It can be seen that the plurality of parallel branches of the battery system have the characteristics of long distance between the setting positions, large temperature difference, significant difference in environmental thermal interference, and obvious temperature difference amplification effect, which poses a great challenge to battery thermal management.

[0063] In the related art, when the parallel branches are thermally managed, the differential effects of the environmental temperature are not effectively considered, which easily leads to a high temperature difference between the branches, affects the cycle life of the branch, and affects the performance of the battery system.

[0064] In view of the above situation, the present application provides a battery thermal management method to effectively thermally manage the battery system including parallel branches and improve the performance of the battery system including parallel branches.

[0065] Figure 4The battery thermal management method of the present application is exemplarily shown.

[0066] Referring to Figure 4 In the present application, the battery thermal management method comprises:

[0067] S100, collecting the ambient temperature and the internal temperature of each branch 1 in the plurality of branches 1 of the battery system 10, each branch 1 having a battery pack and being connected in parallel with each other, and determining the external-internal temperature difference of each branch 1 based on the ambient temperature and the internal temperature of each branch 1.

[0068] The internal temperature of the branch 1, also referred to as the self-temperature of the branch 1, refers to the temperature inside the branch 1 (or the self-temperature), which can be determined by collecting the cell temperature in the battery pack of the branch 1. The ambient temperature of the branch 1 refers to the temperature of the environment in which the branch 1 is located, which is the external temperature of the branch 1. The external-internal temperature difference of the branch 1 is determined according to the difference between the ambient temperature and the internal temperature of the branch 1. For example, in some embodiments, the external-internal temperature difference of the branch 1 is the difference between the ambient temperature at a single point and the internal temperature at a single point of the branch 1, i.e., the external-internal temperature difference of the branch 1 is equal to the ambient temperature at a single point of the branch 1 minus the internal temperature at a single point of the branch 1; or, the external-internal temperature difference of the branch 1 is the difference between the average of the ambient temperature at a plurality of points and the average of the internal temperature at a plurality of points of the branch 1, i.e., the external-internal temperature difference of the branch 1 is equal to the average of the ambient temperature at a plurality of points of the branch 1 minus the average of the internal temperature at a plurality of points of the branch 1.

[0069] In the present application, the average of the internal temperature at a plurality of points of the branch 1 is referred to as the average internal temperature of the branch 1, which can be obtained by collecting the temperature at a plurality of points inside the branch 1, obtaining the internal temperature at a plurality of points, and then taking the average; similarly, the average of the ambient temperature at a plurality of points of the branch 1 is referred to as the average ambient temperature of the branch 1, which can be obtained by collecting the temperature at a plurality of points in the environment in which the branch 1 is located, obtaining the ambient temperature at a plurality of points, and then taking the average.

[0070] Compared with the case of only collecting the ambient temperature and the internal temperature of the branch 1 at a single point, when collecting the ambient temperature and the internal temperature of the branch 1 at a plurality of points, it is more advantageous to more accurately determine the ambient temperature and the internal temperature of the branch 1, and thus more advantageous to accurately control the temperature of the branch 1 and achieve more effective battery thermal management. For example, according to the average ambient temperature and the average internal temperature of each branch 1, the external-internal temperature difference of each branch 1 is determined, which can more accurately determine the external-internal temperature difference of the branch 1, and thus more accurately regulate the temperature of the branch 1 based on step S200 and more effectively reduce the differential impact of the ambient temperature.

[0071] The ambient temperature of each branch 1 at multiple points can be determined by setting multiple points in the environment of each branch 1 respectively to collect the temperature; or, before collecting the ambient temperature of each branch 1 at multiple points, according to the different environment thermal characteristics, the multiple parallel branches 1 can be divided into multiple temperature domains 5, so that the branches 1 with consistent environment thermal characteristics are in the same temperature domain 5, and the consistent environment thermal characteristics include that the ambient temperature is in the same temperature interval, then during the process of collecting the ambient temperature of each branch 1 at multiple points, the ambient temperature of each temperature domain 5 at multiple points is collected, and the ambient temperature of each temperature domain 5 at multiple points is taken as the ambient temperature of each branch 1 at multiple points in each temperature domain 5. In the latter way, it is not necessary to set multiple points in the environment of each branch 1 respectively to collect the temperature to determine the multi-point ambient temperature of each branch 1, but only to divide the branches with small difference in ambient temperature into the same temperature domain, and then set multiple points in each temperature domain to collect the temperature, and take the collected multi-point ambient temperature of the temperature domain as the multi-point ambient temperature of each branch 1 in the same temperature domain, so as to determine the multi-point ambient temperature of each branch 1. Not only can the multi-point ambient temperature of each branch 1 be determined more accurately, but also the number of temperature sensors and the number of collected data can be reduced, and the difficulty of data processing can be reduced, so that the structure can be simplified, the cost can be saved, and the multi-point ambient temperature and the average ambient temperature of each branch 1 can be accurately determined based on a simpler structure and less cost.

[0072] In S200, when the external-internal temperature difference of the branch 1 is greater than the temperature difference threshold, the temperature of the branch 1 is regulated to meet the preset condition, and the preset condition includes that the external-internal temperature difference of the branch 1 is less than or equal to the preset temperature difference value, and the preset temperature difference value is less than or equal to the temperature difference threshold.

[0073] The temperature difference threshold is a preset upper limit value of the external-internal temperature difference of the branch 1. The preset temperature difference value is a preset maximum value of the external-internal temperature difference of the branch 1 when the temperature regulation reaches the standard. Since the preset temperature difference value is less than or equal to the temperature difference threshold, the external-internal temperature difference of the branch 1 is less than or equal to the preset temperature difference value, so that the external-internal temperature difference of the branch 1 is less than or equal to the temperature difference threshold, and is not over-limit.

[0074] In the battery thermal management process, the ambient temperature of the parallel branch is taken into account, not only the ambient temperature of each branch 1 in the parallel branch 1 is collected, but also the external-internal temperature difference of each branch is determined according to the ambient temperature and the internal temperature of each branch 1, and the temperature regulation is performed on the branch 1 whose external-internal temperature difference is greater than the temperature difference threshold, so that the corresponding branch 1 meets the preset condition that the external-internal temperature difference of the branch 1 is less than or equal to the preset temperature difference value. In this way, the external-internal temperature difference of each branch 1 is less than or equal to the preset temperature difference value, the differential influence of the ambient temperature between the parallel branches is effectively reduced, the temperature difference amplification effect between the parallel branches is reduced, the consistency (for example, the internal resistance consistency) between the parallel branches is improved, and the life of the branch is shortened due to the vicious cycle of “temperature rise-promoting, internal resistance reducing, shunt increasing, temperature rise-promoting” is prevented. Therefore, the performance of the battery system 10 can be effectively improved.

[0075] It can be seen that in the process of thermal management of the battery system 10 including the parallel branch, the differential influence of the ambient temperature between the branches can be effectively considered, the temperature difference amplification effect between the parallel branches can be reduced, the consistency between the parallel branches can be improved, the life of each branch in the parallel branch can be prolonged, and the performance of the battery system 10 can be improved.

[0076] In some embodiments, the preset condition not only includes that the external-internal temperature difference of the branch 1 is less than or equal to the preset temperature difference value, but also includes that the average internal temperature of the branch 1 is less than or equal to the preset average temperature value, and / or the highest internal temperature of the branch 1 is less than or equal to the preset high temperature value. The highest internal temperature of the branch 1 is the maximum value of the internal temperatures of the branch 1 at multiple points. The preset average temperature value and the preset high temperature value are the maximum values of the average internal temperature and the highest average temperature of the branch 1 when the temperature regulation meets the standard.

[0077] Based on the above settings, when the external-internal temperature difference of the branch 1 is greater than the temperature difference threshold, the temperature regulation is performed on the branch 1, not only to make the external-internal temperature difference of the branch 1 less than or equal to the preset temperature difference value, but also to make the average temperature of the branch 1 less than or equal to the preset average temperature value, and / or the highest internal temperature of the branch 1 less than or equal to the preset high temperature value. In this way, not only the external-internal temperature difference of each branch 1 can be controlled to be less than or equal to the preset temperature difference value, and the difference between the external-internal temperature differences of the branches 1 is reduced, but also the average internal temperature of each branch 1 can be controlled to be less than or equal to the preset average temperature value and / or the highest internal temperature of each branch 1 can be controlled to be less than or equal to the preset high temperature value, and the difference between the average internal temperatures and / or the highest internal temperatures of the branches 1 is reduced, thereby further reducing the temperature difference between the parallel branches 1, improving the consistency between the parallel branches 1, reducing the temperature difference amplification effect between the parallel branches, prolonging the life of each branch in the parallel branch, and improving the performance of the battery system 10.

[0078] In addition, in some embodiments, the temperature regulation on the branch 1 is not only performed when the temperature difference between the outer and inner temperatures of the branch 1 is greater than the temperature difference threshold, so that the branch 1 meets the preset condition, but also performed when the average internal temperature of the branch 1 exceeds the uniform temperature threshold and / or the maximum internal temperature of the branch 1 exceeds the high temperature threshold, so that the branch 1 meets the preset condition. In this way, the starting conditions of the temperature regulation are more abundant and comprehensive, which can more effectively reduce the temperature difference between the parallel branches 1, improve the consistency between the parallel branches 1, reduce the temperature difference amplification effect between the parallel branches, prolong the service life of each branch in the parallel branches, and improve the performance of the battery system 10.

[0079] In the case where the average internal temperature of the branch 1 exceeds the uniform temperature threshold, i.e., the temperature regulation on the branch 1 is performed so that the branch 1 meets the preset condition, the preset condition can particularly include that the average internal temperature of the branch 1 is less than or equal to a preset uniform temperature value, so as to more effectively reduce the average internal temperature difference between the branches 1, improve the consistency between the parallel branches 1, reduce the temperature difference amplification effect between the parallel branches, prolong the service life of each branch in the parallel branches, and improve the performance of the battery system 10. In this case, the preset uniform temperature value is less than or equal to the uniform temperature threshold.

[0080] In the case where the maximum internal temperature of the branch 1 exceeds the high temperature threshold, i.e., the temperature regulation on the branch 1 is performed so that the branch 1 meets the preset condition, the preset condition can particularly include that the maximum internal temperature of the branch 1 is less than or equal to a preset high temperature value, so as to more effectively reduce the maximum internal temperature difference between the branches 1, improve the consistency between the parallel branches 1, reduce the temperature difference amplification effect between the parallel branches, prolong the service life of each branch in the parallel branches, and improve the performance of the battery system 10. In this case, the preset high temperature value is less than or equal to the high temperature threshold.

[0081] In each of the foregoing embodiments, the temperature regulation on the branch 1 can include:

[0082] Adjusting the flow rate of the cooling liquid in the cooling flow path for cooling the branch 1.

[0083] By adjusting the flow rate of the cooling liquid in the cooling flow path for cooling the branch 1, the cooling strength of the cooling flow path on the branch 1 can be adjusted, so that the temperature of the branch 1 can be adjusted.

[0084] Specifically, in some embodiments, adjusting the flow rate of the cooling liquid in the cooling flow path for cooling the branch 1 includes:

[0085] Adjusting the opening degree of a control valve on the cooling flow path for controlling the flow rate of the cooling liquid.

[0086] The opening degree of the control valve on the cooling flow path for controlling the flow rate of the cooling liquid affects the flow rate of the cooling liquid on the cooling flow path, and further affects the cooling strength, so that adjusting the opening degree of the control valve can achieve the temperature regulation on the branch 1.

[0087] When the temperature of branch 1 is controlled by adjusting the opening of the control valve, it is crucial to determine the target opening of the control valve (i.e., the opening that the control valve needs to be adjusted to). This directly affects the accuracy of temperature control in branch 1, and consequently, whether the consistency between branches can be effectively improved, thus enhancing the performance of the battery system 10.

[0088] In some embodiments, during the adjustment of the control valve opening, the temperature difference between the inside and outside of branch 1 is used as a basis. Determine the target opening degree of the control valve. Specifically, in some embodiments, based on the temperature difference between the inside and outside of branch 1. Determine the target opening degree of the control valve. At that time, based on the temperature difference between the inside and outside of branch 1 With coefficient The product (i.e.) Determine the target opening degree of the control valve. Thus, the target opening degree of the control valve is... Temperature difference between the inside and outside of branch 1 The size is related, which can more effectively adjust the temperature difference between the outside and inside of the branch 1, and make it easier to adjust the temperature difference between the outside and inside of the branch 1 to be less than or equal to the preset temperature difference value, reduce the temperature difference between the outside and inside of the branches, improve the consistency between the branches, and improve the performance of the battery system 10.

[0089] Furthermore, in some embodiments, it is not only based on the temperature difference between the inside and outside of branch 1. To determine the target opening degree of the control valve Furthermore, it is based on the average internal temperature of branch 1. The highest internal temperature of branch 1 and the basic opening of the control valve To determine the target opening degree of the control valve, at least one of the following must be selected. Thus, the target opening degree of the control valve is... Not only the temperature difference between the inside and outside of branch 1 The size is related to, and also to, the average internal temperature of branch 1. The highest internal temperature of branch 1 and the basic opening of the control valve The temperature of branch 1 can be more effectively adjusted by at least one of the following: it is not only easier to adjust the temperature difference between the outside and inside of branch 1 to be less than or equal to the preset temperature difference value, but also easier to adjust at least one of the average internal temperature and the highest internal temperature of branch 1 to the required value. Therefore, it is more conducive to reducing the temperature difference between branches, improving the consistency between branches, and improving the performance of battery system 10.

[0090] Specifically, in some embodiments, based on the average internal temperature of branch 1 determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 (i.e.

[0091] determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e. determining the target opening degree of the control valve based on the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1 (i.e.

[0092] As an example, in some embodiments, the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 and the coefficient are used. The product (i.e.) The difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1, and the coefficient. The product (i.e.) and the basic opening degree of the control valve At least one of them has a temperature difference between the inside and outside of branch 1 and a coefficient. The product (i.e.) The sum of these factors determines the target opening degree of the control valve. This allows for more convenient and precise adjustment of the control valve opening, regulation of the temperature of branch 1, reduction of temperature differences between branches, improvement of consistency between branches, and enhancement of the performance of the battery system 10.

[0093] In some embodiments, the temperature of branch 1 is regulated for a maximum duration. If time If branch 1 still fails to meet the preset conditions, then temperature control of branch 1 is stopped. This limits the time of temperature control, ensuring that the temperature control time does not exceed the set time. Convenient for time If internal temperature control fails to achieve the desired control effect, temperature control should be stopped immediately and other measures should be taken.

[0094] In some embodiments, It is a constant; or, based on the average internal temperature of branch 1. and highest internal temperature At least one of them, determine Among them, when based on the average internal temperature of branch 1 and highest internal temperature At least one of them, determine Time It is not a constant, but varies with the average internal temperature of branch 1. and highest internal temperature At least one of the changes in is determined in this way. The value is more in line with actual needs and makes it easier and more accurate to control the maximum time for temperature regulation of branch 1.

[0095] In some embodiments, based on the average internal temperature of branch 1 When t is determined, the average internal temperature of branch 1 is used as the basis. The target value of the average internal temperature of branch 1 The difference (i.e.) ), determine t. For example, in some embodiments, the average internal temperature of branch 1 is... The target value of the average internal temperature of branch 1 The difference, when t is determined, is based on the average internal temperature of branch 1. The target value of the average internal temperature of branch 1 Difference and coefficient The product (i.e.) ), and determine t. In this way, time t is related to the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1, making it easier to accurately control the maximum time for temperature regulation of branch 1.

[0096] Additionally, in some embodiments, based on the highest internal temperature of branch 1 When t is determined, the highest internal temperature of branch 1 is used as the reference. The target value of the highest internal temperature of branch 1 The difference (i.e.) ), determine t. For example, in some embodiments, at the highest internal temperature of branch 1 The target value of the highest internal temperature of branch 1 The difference, when t is determined, is based on the highest internal temperature of branch 1. The target value of the highest internal temperature of branch 1 Difference and coefficient The product (i.e.) ), determine t. Thus, time t is related to the highest internal temperature of branch 1. The target value of the highest internal temperature of branch 1 The difference makes it easier and more accurate to control the maximum time for temperature regulation of branch 1.

[0097] In some embodiments, it is not only based on the average internal temperature of branch 1 and highest internal temperature At least one of them, determine Moreover, it is based on base time. ,Sure For example, in some embodiments, the difference between the average internal temperature of branch 1 and the target value of the average internal temperature of branch 1 is used as a coefficient. The product of the product and the difference between the highest internal temperature of branch 1 and the target value of the highest internal temperature of branch 1, and the coefficient. At least one of the products of the base time The sum of the numbers determines the outcome. That is, based on and At least one of them is related to the base time. The sum of the numbers determines the outcome. This allows for more accurate and convenient time determination. the size of the branch 1, effectively control the longest time of temperature regulation on the branch 1.

[0098] In some embodiments, if the time is still not met, not only stop the temperature regulation on the branch 1, but also distribute the current among the branches 1 to make the branch 1 meet the preset condition. In this way, after the temperature regulation duration is still unable to meet the requirement of consistency among the branches, the temperature difference among the branches is large, the resistance difference is large, and the current difference is large, the temperature regulation is stopped in time, and the current among the branches is actively distributed to reduce the current difference among the branches and improve the consistency among the branches, forming a hierarchical regulation of temperature regulation (which can also be called temperature compensation) first and current distribution (which can also be called current compensation) second. In this way, in the process of battery thermal management, not only the differentiating influence of environmental temperature is considered, but also the influence of charging and discharging process on the thermal characteristics of the battery pack is considered, effectively solving the problem that the traditional current distribution strategy cannot adapt to the real-time internal resistance change in the process of battery self-heating and environmental temperature coupling, timely and effectively improving the consistency among the branches, avoiding the short board effect of abnormal branches, prolonging the battery life, and improving the performance of the battery system.

[0099] In some embodiments, when the current among the branches 1 is distributed, the current of the branch 1 is determined based on at least one of the average internal temperature and the remaining capacity of the branch 1. Specifically, in some embodiments, when the current of the branch 1 is determined based on at least one of the average internal temperature and the remaining capacity of the branch 1, the current of the branch 1 is determined based on at least one of the difference between the average internal temperature of all parallel branches 1 and the average internal temperature of the branch 1 (i.e. - ) and the difference between the average remaining capacity of all branches 1 and the remaining capacity of the branch 1 (i.e. ). In this way, in the current distribution process, the current of each branch is related to the average internal temperature and the remaining capacity of itself, and the current required to be distributed by each branch can be more accurately determined, and the consistency among the branches can be more effectively improved, and the performance of the battery system 10 can be improved.

[0100] In addition, in some embodiments, a PID algorithm is used to distribute the current among the branches 1. For example, in some embodiments, the current of the branch 1 is determined according to the following formula:

[0101]

[0102] wherein, is a base current, which is equal to the total current divided by the number of branches, is an average internal temperature of all branches 1, is an average internal temperature of branch 1, is an average remaining power of all branches 1, is a remaining power of branch 1, , and are PID parameters.

[0103] In the above embodiments, based on the difference between the average internal temperature of all branches 1 and the average internal temperature of branch 1 (i.e. - ), the difference between the average remaining power of all branches 1 and the remaining power of branch 1 (i.e. ), and the base current , the PID algorithm is used to dynamically adjust the current of branch 1, so as to realize the distribution of the current among the branches, which can more effectively improve the consistency of the current among the branches, prolong the life of the battery system 10, and improve the performance of the battery system 10.

[0104] Referring to Figure 1 , in order to realize the current compensation in the above embodiments, a converter 3 can be arranged between the branch 1 and the load end 4 or the charging end (not shown) to isolate the branch 1 from the load end 4 or the charging end, and the current is distributed through the converter 3, so that the current of the branch 1 is no longer completely affected by the load end 4 or the charging end, but can be actively distributed.

[0105] In some embodiments, if the current distribution among the branches 1 still cannot make the branches 1 meet the preset conditions, one of the current limiting, the power-off of the abnormal branch 1, and the power-off of the battery system 10 is used to isolate the abnormal branch 1. In this way, in the case that the current distribution among the branches still cannot meet the requirement of the consistency among the branches, the active isolation of the abnormal branch is started in time to prevent the abnormal branch from aggravating the difference among the branches, so as to form a hierarchical regulation of temperature regulation (which can also be called temperature compensation) first, current distribution (which can also be called current compensation) second, and offline isolation last, which can more effectively avoid the short board effect of the abnormal branch, prolong the life of the battery system, and improve the performance of the battery system.

[0106] The three isolation modes, i.e. current limiting, abnormal branch power-off and battery system power-off, can be adopted respectively in the case that the fault level of the abnormal branch 1 belongs to the first, second and third fault levels, and the abnormal types of the branch 1 corresponding to the first, second and third fault levels increase in turn.

[0107] For example, in some embodiments, the abnormal types that can occur in the branch include: (1) the average temperature of the branch is too high; (2) the cell temperature of the branch is too high; (3) the cumulative temperature rise of the branch is too high; (4) the temperature rise rate of the branch is too fast; (5) the temperature difference between the clusters is too large; and (6) communication is abnormal or interrupted, etc. According to the order from few to many of the abnormal types of the branch, the fault levels are divided into the first, second and third fault levels from light to heavy, and the first, second and third fault levels correspond to the three isolation modes of current limiting, abnormal branch power-off and battery system power-off respectively.

[0108] In the above embodiments, according to the order from light to heavy of the fault levels of the abnormal branch, the isolation modes are selected in turn according to the order of current limiting, abnormal branch power-off and battery system power-off. In the case that the abnormal types of the branch are few, the low fault level (corresponding to the first fault level), the current limiting mode is adopted for isolation; in the case that the abnormal types of the branch are moderate, the medium fault level (corresponding to the second fault level), the abnormal branch power-off mode is adopted for isolation; and in the case that the abnormal types of the branch are many, the high fault level (corresponding to the third fault level), the battery system power-off mode is adopted for isolation. In this way, the corresponding isolation measures can be implemented in turn according to the fault levels, and the grading response mechanism in the case of fast temperature rise or communication abnormality can be realized, which effectively reduces the failure risk of the battery system in extreme working conditions and improves the safety performance of the battery system.

[0109] Based on the battery thermal management method of each of the foregoing embodiments, the application further provides a controller. The controller includes a memory and a processor coupled to the memory, and the processor is configured to execute the battery thermal management method of any one of the embodiments based on instructions stored in the memory.

[0110] In addition, the application also provides a mechanical system, which includes the battery system 10 and the controller of any one of the embodiments. In some embodiments, the battery system 10 further includes a converter 3, which is electrically connected between the branch 1 and the load end 4 and / or the charging end. The mechanical system can be a large-tonnage device such as a construction machine, and the battery system 10 can be a large-capacity battery system.

[0111] Next, further introduce Figures 1-4 the embodiments shown.

[0112] As Figures 1-2As shown, in this embodiment, the mechanical system is an engineering vehicle, and its battery system 10 includes multiple parallel branches 1 (eight in this example). These parallel branches 1 are distributed in different locations such as the frame and chassis, where the ambient temperature varies considerably, and each branch includes a battery pack with individual cells. The number of battery packs on each branch can be the same or different; for example, in some embodiments, some branches have a single battery pack, while others have multiple battery packs connected in series. Figure 1 In the diagram, these parallel branches are labeled 1#, 2#, ..., and can be referred to as branch 1, branch 2, ... for ease of description.

[0113] To facilitate thermal management of each branch 1, such as Figure 2 As shown, in this embodiment, the battery system 10 further includes a temperature acquisition module 21 and an electrical acquisition module 22, which respectively acquire the temperature signal and electrical signal of the branch 1. The temperature acquisition module 21 includes a temperature sensor (which may be called an ambient temperature sensor) disposed in the environment for acquiring the ambient temperature, and a temperature sensor (which may be called an internal temperature sensor) disposed inside the branch 1 for acquiring the internal temperature of the branch.

[0114] And, as Figure 2 As shown, in this embodiment, a converter 3 is provided between branch 1 and load terminal 4 to isolate branch 1 and load terminal 4, facilitating current distribution. Figure 2 In this circuit, there is not a one-to-one correspondence between branch 1 and converter 3. Instead, some branches 1 share a single converter 3. However, it is understandable that this is not the only way to configure converter 3.

[0115] right Figures 1-2 The battery system 10, in this embodiment, employs a three-level control strategy of "temperature compensation – current compensation – fault isolation" based on temperature domain division for battery thermal management. The battery thermal management method combines... Figures 3-4 This will be explained.

[0116] (I) Temperature Domain Division

[0117] like Figure 3 As shown, based on the physical distribution of multiple parallel branches 1 on the vehicle (considering the sunlight 6, the obstruction 7, and the airflow 8 at the distribution locations) and the temperature field distribution results of the vehicle thermal simulation, the multiple parallel branches 1 are divided into several independent temperature domains 5 (e.g., Figure 3 The first temperature domain 51, the second temperature domain 52, and the third temperature domain 53 shown have branches within each temperature domain 5 that have consistent (identical or similar) environmental thermal characteristics. For example, Figure 3In the first temperature domain 51, the ambient temperature of each branch 1 is in a temperature interval greater than or equal to a first temperature value, in the second temperature domain 52, the ambient temperature of each branch 1 is in a temperature interval less than the first temperature value and greater than or equal to a second temperature value, and in the third temperature domain 53, the ambient temperature of each branch 1 is in a temperature interval less than the second temperature value. At this time, the first temperature domain 51, the second temperature domain 52 and the third temperature domain 53 can also be referred to as high-temperature domain, medium-temperature domain or low-temperature domain respectively. In other embodiments, the environmental thermal characteristics are consistent, not only including that the ambient temperature is in the same temperature interval, but also including that the ambient temperature change is similar, for example, the ambient temperature change in a day is not much different.

[0118] For each temperature domain 5, ambient temperature sensors are arranged at multiple typical positions to collect the ambient temperature of the temperature domain, and the ambient temperature at multiple points is obtained , denoted as ( =1, 2, 3… , is the number of temperature detection points in the temperature domain 5; =1, 2, 3… , is the number of temperature domains 5 in the battery system 10); and, inside each branch 1, multiple internal temperature sensors are arranged to collect the temperature of multiple single bodies on the branch 1, and the internal temperature of each branch 1 at multiple points is obtained , denoted as ( =1, 2, 3… , is the number of temperature detection points in the branch 1; =1, 2, 3… , is the number of branches 1 in the temperature domain 5).

[0119] The average ambient temperature of the temperature domain is defined as: =( ) / .

[0120] The average internal temperature of the branch in the temperature domain is defined as: =( ) / .

[0121] The highest temperature of the branch in the temperature domain is defined as: .

[0122] The highest temperature of the temperature domain Middle branch The external-internal temperature difference of the middle branch is: .

[0123] (II) Primary regulation: temperature compensation

[0124] Each branch 1 is configured with an independent liquid cooling branch and a control valve (e.g., a solenoid valve), and the opening degree of the control valve can be adjusted through an analog signal or a digital signal.

[0125] Conditions for triggering temperature compensation:

[0126] 1) The average internal temperature of the branch exceeds the limit: ( is the preset uniform temperature threshold);

[0127] 2) The highest internal temperature of the branch exceeds the limit: ( is the preset high temperature threshold);

[0128] 3) The external-internal temperature difference of the branch exceeds the limit: ( is the preset temperature difference threshold).

[0129] When any of the above conditions is met, the opening degree of the control valve corresponding to the branch 1 is increased, and the adjustment formula is:

[0130]

[0131] wherein, is the target opening degree of the control valve corresponding to the branch in the temperature domain , is the reference opening degree of the control valve, is the target value of the average internal temperature of the branch in the temperature domain , is the target value of the highest internal temperature of the branch in the temperature domain ; , and are proportional adjustment coefficients obtained through experimental calibration. , and are proportional adjustment coefficients obtained through experimental calibration.

[0132] The temperature compensation time is set as:

[0133]

[0134] wherein, is the basic compensation time, and ​The time coefficient corresponding to the temperature deviation.

[0135] In the time , if the preset average temperature value, the preset high temperature value, and the preset temperature difference value, the temperature compensation is stopped.

[0136] Among them, , and are determined based on the unit energy consumption, simulated working conditions and real vehicle calibration.

[0137] If the above conditions are not met after the time is exceeded, secondary regulation is triggered.

[0138] (Three) Secondary regulation: current compensation

[0139] When the consistency between branches is pulled apart, there is a difference in resistance between branches, and simply increasing the external cooling intensity cannot effectively solve the temperature difference problem between branches, which is easy to induce single cell out-of-group, leading to more serious consequences. In view of this, the embodiment adopts a current equalization method based on current compensation to deal with the corresponding problems.

[0140] Based on the converter 3 shown in Figure 3 , the embodiment adopts PID algorithm dynamic adjustment to realize current distribution. For the branch in the temperature domain , the current distribution formula is as follows:

[0141]

[0142] Among them:

[0143] is the target current of the branch in the temperature domain , is the reference current (total current / branch number);

[0144] is the average internal temperature of all branches, is the average remaining power of all branches, is the remaining power of the branch in the temperature domain ;

[0145] , and are PID parameters, which are obtained through real vehicle calibration.

[0146] In the process of secondary regulation, the current can be balanced, and the consistency of the electric quantity among the branches can be regulated, and active balancing or active discharge can be adopted to reduce the difference in electric quantity among the branches in the process of current distribution. For example, part of the branch is limited to current, and the remaining electric quantity (SOC, State Of Charge) may be large, in which case, the branches can be connected to each other, so that the branch with a large SOC can compensate for the branch with a small SOC, thereby maintaining the consistency of the SOC among the branches.

[0147] (Four) Third regulation: fault isolation

[0148] When the above-mentioned temperature compensation and current compensation are invalid, the risk of thermal runaway induced by battery failure or internal problem is considered, and the abnormal branch needs to be actively isolated. When the branch meets one or more of the following conditions, the corresponding measures are taken in order according to the fault level.

[0149] The judgment conditions are as follows: 1) the average temperature of the branch is too high; 2) the single cell temperature of the branch is too high; 3) the cumulative temperature rise of the branch is too high; 4) the temperature rise rate of the branch is too fast; 5) the temperature difference among the branches is too large; 6) communication is abnormal or interrupted, etc. At this time, the different fault levels are processed in the order of limiting current - powering off the fault branch - powering off the system.

[0150] It can be seen that in the process of thermal management of the battery system including multiple parallel branches, the temperature difference among the branches and the dynamic influence of the charging and discharging process on the thermal characteristics of the battery pack are considered, the state and cause of the battery system are understood from more angles, and combined with the temperature domain division and the three-level regulation strategy of "temperature compensation - current compensation - fault isolation", the following problems can be effectively solved:

[0151] 1) The temperature difference amplification effect of multiple parallel branches: when the branch temperature rises, the internal resistance decreases, the shunt increases, the temperature rise forms a positive feedback, and then the temperature difference among the branches is aggravated;

[0152] 2) Dynamic interference of charging and discharging: during the charging and discharging process, the battery self-heating is coupled with the environmental temperature, and the traditional fixed current distribution strategy cannot adapt to the real-time internal resistance change;

[0153] 3) Risk of loss of control in extreme conditions: the existing temperature control means lacks a hierarchical response mechanism when the temperature rises too fast or the communication is abnormal, which is easy to cause system-level failure.

[0154] Therefore, the short board effect of the abnormal branch can be effectively avoided, the consistency among the parallel branches can be improved, and the performance of the battery system can be improved.

[0155] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not to limit the technical solutions of the present application; although the present application is explained in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones, and all of them should be covered in the technical solution range claimed by the present application.

Claims

1. A method of battery thermal management, the method comprising: The method comprises: collecting the ambient temperature and internal temperature of each branch (1) of a plurality of parallel branches (1) each having a battery pack of a battery system (10), and determining the external-internal temperature difference of each branch (1) based on the ambient temperature and internal temperature of each branch (1); in the case where the external-internal temperature difference of the branch (1) is greater than a temperature difference threshold, performing temperature regulation on the branch (1) to make the branch (1) meet a preset condition, the preset condition comprising that the external-internal temperature difference of the branch (1) is less than or equal to a preset temperature difference value, and the preset temperature difference value is less than or equal to the temperature difference threshold.

2. The battery thermal management method of claim 1, wherein, The collecting the ambient temperature and internal temperature of each branch (1) of a plurality of parallel branches (1) and determining the external-internal temperature difference of each branch (1) based on the ambient temperature and internal temperature of each branch (1) comprises: collecting the internal temperature at a plurality of points and the ambient temperature at a plurality of points of each branch (1), and determining the external-internal temperature difference of each branch (1) based on the average ambient temperature and average internal temperature of each branch (1); wherein the average internal temperature of each branch (1) is the average value of the internal temperature at a plurality of points of each branch (1), and the maximum internal temperature of each branch (1) is the maximum value in the internal temperature at a plurality of points of each branch (1).

3. The battery thermal management method of claim 2, wherein before collecting the ambient temperature at a plurality of points of each branch (1), the plurality of parallel branches (1) are divided into a plurality of temperature domains (5) according to different environmental thermal characteristics, so that branches (1) with consistent environmental thermal characteristics are in the same temperature domain (5), and the consistent environmental thermal characteristics comprise that the ambient temperature is in the same temperature interval; in the process of collecting the ambient temperature at a plurality of points of each branch (1), the ambient temperature at a plurality of points of each temperature domain (5) is collected, and the ambient temperature at a plurality of points of each temperature domain (5) is taken as the ambient temperature at a plurality of points of each branch (1) in each temperature domain (5).

4. The battery thermal management method of claim 1, wherein, The preset condition further comprises: the average internal temperature of the branch (1) is less than or equal to a preset average temperature value, wherein the average internal temperature of the branch (1) is the average value of the internal temperature at a plurality of points of the branch (1); and / or the maximum internal temperature of the branch (1) is less than or equal to a preset high temperature value, wherein the maximum internal temperature of the branch (1) is the maximum value in the internal temperature at a plurality of points of the branch (1).

5. The battery thermal management method of claim 1, wherein, The battery thermal management method further comprises at least one of: in the case where the average internal temperature of the branch (1) exceeds an average temperature threshold, performing temperature regulation on the branch (1) to make the branch (1) meet the preset condition, the preset condition further comprising that the average internal temperature of the branch (1) is less than or equal to a preset average temperature value, and the preset average temperature value is less than or equal to the average temperature threshold, and the average internal temperature of the branch (1) is the average value of the internal temperature at a plurality of points of the branch (1); In a case where the highest internal temperature of the branch circuit (1) exceeds a high temperature threshold, temperature regulation is performed on the branch circuit (1) to make the branch circuit (1) meet the preset condition, which further includes that the highest internal temperature of the branch circuit (1) is less than or equal to a preset high temperature value, and the preset high temperature value is less than or equal to the high temperature threshold, and the highest internal temperature of the branch circuit (1) is the maximum value of the internal temperatures of the branch circuit (1) at multiple points.

6. The battery thermal management method of any one of claims 1-5, wherein, The temperature regulation on the branch circuit (1) includes: Adjusting the flow of the cooling liquid in the cooling flow path for cooling the branch circuit (1).

7. The battery thermal management method of claim 6, wherein, The adjustment of the flow of the cooling liquid in the cooling flow path for cooling the branch circuit (1) includes: Adjusting the opening of a control valve on the cooling flow path for controlling the flow of the cooling liquid.

8. The battery thermal management method of claim 7, wherein, In the process of adjusting the opening of the control valve, the target opening of the control valve is determined based on the external-internal temperature difference of the branch circuit (1).

9. The battery thermal management method of claim 8, wherein, When determining the target opening degree of the control valve based on the outside-inside temperature difference of the branch (1), the target opening degree of the control valve is determined based on the product of the outside-inside temperature difference of the branch (1) and a coefficient .

10. The battery thermal management method of claim 8, wherein, The target opening of the control valve is further determined based on at least one of the average internal temperature of the branch circuit (1), the highest internal temperature of the branch circuit (1), and a basic opening of the control valve, wherein the average internal temperature of the branch circuit (1) is the average value of the internal temperatures of the branch circuit (1) at multiple points, and the highest internal temperature of the branch circuit (1) is the maximum value of the internal temperatures of the branch circuit (1) at multiple points.

11. The battery thermal management method of claim 10, wherein, In a case where the target opening of the control valve is determined based on the average internal temperature of the branch circuit (1), the target opening of the control valve is determined based on the difference between the average internal temperature of the branch circuit (1) and a target value of the average internal temperature of the branch circuit (1); and / or, in a case where the target opening of the control valve is determined based on the highest internal temperature of the branch circuit (1), the target opening of the control valve is determined based on the difference between the highest internal temperature of the branch circuit (1) and a target value of the highest internal temperature of the branch circuit (1).

12. The battery thermal management method of claim 11, wherein, determining the target opening degree of the control valve based on the difference between the average internal temperature of the branch (1) and the target value of the average internal temperature of the branch (1) and the product of the difference between the average internal temperature of the branch (1) and the target value of the average internal temperature of the branch (1) and a coefficient determining the target opening degree of the control valve based on the difference between the highest internal temperature of the branch (1) and the target value of the highest internal temperature of the branch (1) and the product of the difference between the highest internal temperature of the branch (1) and the target value of the highest internal temperature of the branch (1) and a coefficient determining the target opening degree of the control valve based on the difference between the average internal temperature of the branch (1) and the target value of the average internal temperature of the branch (1) and the product of the difference between the average internal temperature of the branch (1) and the target value of the average internal temperature of the branch (1) and a coefficient 13. The battery thermal management method of claim 12, wherein, a product of a difference between the average internal temperature of the branch (1) and a target value of the average internal temperature of the branch (1) and a coefficient a product of a difference between the maximum internal temperature of the branch (1) and a target value of the maximum internal temperature of the branch (1) and a coefficient a product of a difference between the average internal temperature of the branch (1) and a target value of the average internal temperature of the branch (1) and a coefficient a sum of at least one of a product of a difference between the external internal temperature difference of the branch (1) and a coefficient 14. The battery thermal management method of any one of claims 1-5, wherein, controlling the temperature of the branch (1) for a duration if the branch (1) does not meet the predetermined condition after a time stopping the temperature control of the branch (1).

15. The battery thermal management method of claim 14, wherein, is constant; or, based on at least one of an average internal temperature and a maximum internal temperature of the branch (1), determining wherein the average internal temperature of the branch (1) is an average of the internal temperatures of the branch (1) at a plurality of points, and the maximum internal temperature of the branch (1) is a maximum of the internal temperatures of the branch (1) at a plurality of points.

16. The battery thermal management method of claim 15, wherein, In a case where t is determined based on the average internal temperature of the branch circuit (1), t is determined based on the difference between the average internal temperature of the branch circuit (1) and a target value of the average internal temperature of the branch circuit (1); and / or, in a case where t is determined based on the highest internal temperature of the branch circuit (1), t is determined based on the difference between the highest internal temperature of the branch circuit (1) and a target value of the highest internal temperature of the branch circuit (1).

17. The battery thermal management method of claim 16, wherein, determining t on the basis of the difference between the average internal temperature of the branch (1) and a target value for the average internal temperature of the branch (1), determining t on the basis of the product of the difference between the average internal temperature of the branch (1) and a target value for the average internal temperature of the branch (1) and a factor determining t on the basis of the difference between the maximum internal temperature of the branch (1) and a target value for the maximum internal temperature of the branch (1), determining t on the basis of the product of the difference between the maximum internal temperature of the branch (1) and a target value for the maximum internal temperature of the branch (1) and a factor determining t on the basis of the difference between the maximum internal temperature of the branch (1) and a target value for the maximum internal temperature of the branch (1), determining t on the basis of the product of the difference between the maximum internal temperature of the branch (1) and a target value for the maximum internal temperature of the branch (1) and a factor 18. The battery thermal management method of claim 15, wherein, Also based on the base time , it is determined .

19. The battery thermal management method of claim 18, wherein, based on at least one of a product of a difference between the average internal temperature of the branch (1) and a target value of the average internal temperature of the branch (1) and a coefficient a product of a difference between the maximum internal temperature of the branch (1) and a target value of the maximum internal temperature of the branch (1) and a coefficient and a base time to determine .

20. The battery thermal management method of claim 14, wherein, If the time After the time, if the branch (1) still does not meet the preset condition, the temperature regulation of the branch (1) is stopped, and the current distribution among the branches (1) is performed to make the branches (1) meet the preset condition.

21. The battery thermal management method of claim 20, wherein, In the current distribution among the branch circuits (1), the current of the branch circuit (1) is determined based on at least one of the average internal temperature of the branch circuit (1) and the residual power of the branch circuit (1); and / or, the PID algorithm is used for the current distribution among the branch circuits (1).

22. The battery thermal management method of claim 21, wherein, In a case where the current of the branch circuit (1) is determined based on at least one of the average internal temperature of the branch circuit (1) and the residual power of the branch circuit (1), the current of the branch circuit (1) is determined based on at least one of the difference between the average internal temperature of all parallel branch circuits (1) and the average internal temperature of the branch circuit (1), and the difference between the average residual power of all branch circuits (1) and the residual power of the branch circuit (1).

23. The battery thermal management method of claim 22, wherein, In determining the current of the branch (1) based on the difference between the average internal temperature of all branches (1) and the average internal temperature of the branch (1) and the difference between the average residual electric quantity of all branches (1) and the residual electric quantity of the branch (1), the current of the branch (1) is determined according to the following formula : wherein, is equal to the total current divided by the number of branches, is the average internal temperature of all branches (1), is the average internal temperature of the branch (1), is the average remaining power of all branches (1), is the remaining power of the branch (1), , and are PID parameters.

24. The battery thermal management method of claim 20, wherein, If the current distribution among the branches (1) still cannot make each branch (1) meet the preset condition, one of current limiting, abnormal branch power-off and battery system power-off is used to isolate the abnormal branch.

25. The battery thermal management method of claim 24, wherein, The three modes of current limiting, abnormal branch power-off and battery system power-off are used respectively in the case that the fault level of the abnormal branch belongs to the first level fault, the second level fault and the third level fault, and the abnormal types of the branch (1) corresponding to the first level fault, the second level fault and the third level fault increase in turn.

26. A controller characterized by A memory and a processor coupled to the memory, the processor configured to perform the battery thermal management method of any of claims 1-24 based on instructions stored in the memory.

27. A mechanical system comprising a battery system (10) comprising a plurality of parallel branches (1), each branch (1) comprising a battery pack with a single cell, characterized in that, The mechanical system further comprises the controller of claim 26.

28. The mechanical system of claim 27, wherein, The battery system (10) further comprises a converter (3) electrically connected between the branch (1) and a load end (4) and / or a charging end.

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