Thermal management system and method for power battery

Abstract

The application discloses a kind of thermal management system and thermal management method of power battery, and thermal management method includes the following steps: S1: the state information of power battery is acquired, and whether power battery starts to work is judged;If yes, then execute step S2;S2: the highest temperature of battery cell is acquired, and whether the highest temperature of battery cell is greater than temperature threshold is judged;If yes, then execute step S3;If no, then continue to execute step S2;S3: whether inlet air temperature sensor is effective is judged;If yes, then execute step S4;S4: inlet air temperature is acquired, and whether the difference of the highest temperature of battery cell minus inlet air temperature is greater than difference threshold is judged;If yes, then execute step S5;If no, control fan to run according to lowest gear continuously, continue to execute step S4;S5: according to the minimum value of fan air volume in unit time determined, determine fan gear, control fan to run according to determined gear continuously, can accurately control inlet air volume, reduce the energy consumption of fan.

Description

TECHNICAL FIELD

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

[0002] The existing cell cooling mainly includes water cooling, natural cooling, active air cooling and the like, wherein the water cooling has good cooling effect, but the cost is relatively high, and it is suitable for large-capacity energy type power battery, such as pure electric vehicle; the natural cooling has poor cooling effect, and has high requirement on the cooling conduction of the internal heat of the cell, and is suitable for power battery with low heat dissipation requirement, such as pure electric vehicle or plug-in hybrid vehicle; the active air cooling has moderate cooling effect, the cooling system is simple in design, and the cost is low, and it is suitable for power battery with high heat dissipation requirement and low capacity, such as hybrid vehicle. At present, if the power battery is cooled by the active air cooling mode, the problem of large energy consumption of the fan exists. SUMMARY

[0003] The present application aims to solve the problem of large energy consumption of the fan in the prior art. The present application provides a thermal management method of power battery, which can accurately control the air inlet amount and reduce the energy consumption of the fan.

[0004] The present application discloses a thermal management method of power battery, the power battery comprising a plurality of cells; the thermal management method comprising the following steps:

[0005] S1: obtaining the state information of the power battery, and determining whether the power battery starts to work according to the state information of the power battery;

[0006] If yes, step S2 is executed;

[0007] If no, step S1 is continuously executed.

[0008] S2: obtaining the highest temperature of the cell, and determining whether the highest temperature of the cell is greater than a temperature threshold;

[0009] If yes, step S3 is executed;

[0010] If no, step S2 is continuously executed.

[0011] S3: obtaining the state information of the collection loop of the air inlet temperature sensor, and determining whether the air inlet temperature sensor is effective according to the state information of the collection loop; the air inlet temperature sensor is arranged at the air inlet of the power battery, and is used for obtaining the air inlet temperature;

[0012] If yes, step S4 is executed;

[0013] If not, the fan is controlled to run at the lowest gear for a time t1, then the fan is controlled to run at the highest gear, and a fault information of the air inlet temperature sensor is sent to the whole vehicle. The fan is arranged at an air outlet of the power battery.

[0014] S4: Obtain the air inlet temperature, and determine whether the difference between the maximum temperature of the battery cell and the air inlet temperature is greater than a difference threshold value;

[0015] If yes, step S5 is executed;

[0016] If not, the fan is controlled to run at the lowest gear for a time t2, and step S4 is continuously executed.

[0017] S5: Determine the minimum value of the air volume of the fan per unit time according to the following formula:

[0018]

[0019] Wherein, Q is the air volume of the fan per unit time, q is the heat generated by the current of the power battery per unit time, c is the specific heat capacity of air, p is the air density inside the power battery, and AT1 is the absolute value of the difference between the maximum temperature of the battery cell and the air inlet temperature;

[0020] The gear of the fan is determined according to the minimum value of the air volume of the fan per unit time, and the fan is controlled to run at the determined gear.

[0021] According to the technical scheme, after the maximum temperature of the battery cell is obtained, if the maximum temperature of the battery cell is greater than a temperature threshold value, after the air inlet temperature is obtained, it is determined whether the difference between the maximum temperature of the battery cell and the air inlet temperature is greater than a difference threshold value. If it is determined that the difference between the maximum temperature of the battery cell and the air inlet temperature is greater than the difference threshold value, the gear of the fan is determined according to the minimum value of the air volume of the fan per unit time, and the fan is controlled to run at the determined gear. In this way, the air inlet volume can be accurately controlled, and the energy consumption of the fan can be reduced. In addition, before the fan is controlled to run at the gear, it is necessary to determine whether the air inlet temperature sensor is effective. If it is determined that the air inlet temperature sensor is ineffective, a fault information of the air inlet temperature sensor is sent to the whole vehicle. In this way, the situation that the determined gear of the fan is inaccurate due to the inaccurate air inlet temperature obtained because the air inlet temperature sensor is ineffective can be avoided. If the obtained air inlet temperature is higher than the actual air inlet temperature, the gear of the fan is determined to be too high, which increases the energy consumption of the fan. If the obtained air inlet temperature is lower than the actual air inlet temperature, the gear of the fan is determined to be too low, which affects the cooling effect, causes the temperature of the power battery to be too high, and affects use.

[0022] According to another specific embodiment of the present application, the power battery thermal management method disclosed by the embodiment of the present application selects the duty cycle corresponding to the minimum air volume in the air volume greater than the minimum value of the air volume of the fan per unit time to determine the gear of the fan according to the relationship between the minimum value of the air volume of the fan per unit time, the duty cycle corresponding to the gear, and the air volume of the fan.

[0023] By adopting the technical scheme, the duty ratio corresponding to the minimum air volume in the air volume greater than the minimum value of the determined air volume of the fan is selected to determine the gear of the fan, so that the heat carried away by the air volume generated by the determined gear of the fan is greater than or equal to the heat generated by the current of the power battery, thereby ensuring the wind cooling effect, and the gear corresponding to the minimum air volume is selected on the basis of ensuring the wind cooling effect, so that the energy consumption of the fan is the lowest.

[0024] According to another specific embodiment of the present application, the power battery thermal management method disclosed by the embodiment of the present application further comprises:

[0025] S6: During the operation of the fan, a plurality of battery cell temperatures are acquired, a maximum battery cell temperature difference is determined according to the plurality of battery cell temperatures, and it is determined whether the maximum battery cell temperature difference is greater than a battery cell temperature difference threshold value;

[0026] If yes, step S7 is executed;

[0027] If no, the fan is controlled to continue operating at the current gear, and step S6 is continuously executed.

[0028] S7: Gear information of the fan operation is acquired, and it is determined whether the fan is at a lowest gear according to the gear information;

[0029] If yes, the fan is controlled to operate at the lowest gear;

[0030] If no, the fan is controlled to operate at a lower gear for a time t3, and step S6 is continuously executed.

[0031] By adopting the technical scheme, during the operation of the fan, a plurality of battery cell temperatures are acquired, a maximum battery cell temperature difference is determined according to the plurality of battery cell temperatures, and it is determined whether the maximum battery cell temperature difference is greater than a battery cell temperature difference threshold value, if it is determined that the maximum battery cell temperature difference is greater than the battery cell temperature difference threshold value and the fan is not at the lowest gear, the fan is controlled to operate at a lower gear, thereby improving the working consistency of the battery cells and prolonging the service life of the power battery.

[0032] According to another specific embodiment of the present application, the power battery thermal management method disclosed by the embodiment of the present application, the temperature threshold value ranges from 28 to 32℃, the difference threshold value ranges from 1 to 2℃, the battery cell temperature difference threshold value is 10℃, the time t1 ranges from 1 to 5 minutes, the time t2 is 30 seconds, and the time t3 is 20 seconds.

[0033] According to another specific embodiment of the present application, the power battery thermal management method disclosed by the embodiment of the present application, in step S3, determining whether the air inlet temperature sensor is valid according to the state information of the acquisition circuit comprises: if the acquisition circuit is an open circuit or a short circuit, it is determined that the air inlet temperature sensor is invalid; otherwise, the air inlet temperature sensor is valid.

[0034] By using the technical scheme, if the collection circuit is open or short, it is judged that the inlet air temperature sensor is invalid; otherwise, the inlet air temperature sensor is valid, so that the method for judging whether the inlet air temperature sensor is valid is simple and convenient.

[0035] According to another specific embodiment of the present application, the power battery thermal management method disclosed by the embodiment of the present application comprises the following steps: in the process of running the fan, real-time acquisition of gear information of the running fan is performed; and according to the gear information and the determined gear, it is judged whether the fan runs according to the determined gear.

[0036] If yes, the fan continues to run according to the determined gear;

[0037] If no, the fan failure information is sent to the whole vehicle, and the fan is controlled to run according to the highest gear.

[0038] By using the technical scheme, through real-time acquisition of gear information of the running fan, according to the gear information and the determined gear, it is judged whether the fan runs according to the determined gear, if it is judged that the fan does not run according to the determined gear, the fan failure information is sent to the whole vehicle, and the fan is controlled to run according to the highest gear, so that the situation that the fan does not run according to the determined gear and affects the power battery air cooling effect or increases the power consumption of the fan can be avoided.

[0039] The embodiment of the present application discloses a power battery thermal management system for executing the power battery thermal management method, and the power battery comprises a battery module, a battery upper cover and a battery base; one end of the battery upper cover is open, and the battery module is arranged inside the battery upper cover; opposite sides of the battery upper cover are respectively provided with a first through hole and a second through hole; and the battery module comprises a plurality of spaced-apart battery cells.

[0040] The thermal management system comprises an air inlet duct, an upper air duct, a lower air duct, an air outlet duct, a fan, an inlet air temperature sensor and a plurality of battery cell temperature sensors; the fan, the inlet air temperature sensor and each battery cell temperature sensor are connected with a battery management system.

[0041] The air inlet duct and the air outlet duct are arranged on opposite sides of the battery upper cover; the upper air duct and the lower air duct are arranged inside the battery upper cover and on opposite sides of the battery module; one end of the air inlet duct penetrates through the first through hole and is connected with one end of the upper air duct, and one end of the air outlet duct penetrates through the second through hole and is connected with one end of the lower air duct; the fan is arranged at one end of the air outlet duct away from the battery upper cover; the inlet air temperature sensor is arranged on the air inlet duct; the battery cell temperature sensors are arranged on the battery cells, and the battery cell temperature sensors are arranged on the battery cells at both ends and in the middle of the battery module; and the battery management system is arranged inside the power battery.

[0042] The fan, the air inlet temperature sensor and each battery cell temperature sensor are connected with the battery management system, the air inlet temperature sensor acquires the air inlet temperature in real time and sends the air inlet temperature to the battery management system, the plurality of battery cell temperature sensors acquire the plurality of battery cell temperatures in real time and send the plurality of battery cell temperatures to the battery management system, the battery management system receives the air inlet temperature and the plurality of battery cell temperatures and controls the gear of the fan according to the air inlet temperature and the plurality of battery cell temperatures, and the fan operates according to the determined gear, so that the air inlet amount can be accurately controlled and the energy consumption of the fan can be reduced.

[0043] According to another specific embodiment of the present application, the power battery thermal management system disclosed by the embodiment of the present application further comprises a filter element, the filter element is arranged at an inlet of the air inlet channel and detachably connected with the air inlet channel.

[0044] According to the above technical scheme, by arranging the filter element at the inlet of the air inlet channel, on the one hand, the cleanliness of the surface of the battery cell can be improved, and the efficiency of the thermal management performance of the power battery in the whole life cycle can be maintained; on the other hand, the probability of accumulation of impurities in the power battery can be reduced, and the risk of thermal runaway of the power battery caused by short circuit due to impurities can be reduced.

[0045] According to another specific embodiment of the present application, the power battery thermal management system disclosed by the embodiment of the present application further comprises an air door, the air door is arranged at one end of the air inlet channel close to the battery module and detachably connected with the air inlet channel.

[0046] According to the above technical scheme, by arranging the air door, once the power battery occurs thermal runaway, the air door is closed by relying on the large air pressure generated by the thermal runaway, so that the oxygen entering the inside of the power battery is reduced, and the harmful gas in the power battery is prevented from diffusing to the passenger cabin.

[0047] According to another specific embodiment of the present application, the power battery thermal management system disclosed by the embodiment of the present application further comprises an air door, the air door is arranged at one end of the air inlet channel close to the battery module and detachably connected with the air inlet channel.

[0048] According to the above technical scheme, each air leaf is rotatable relative to the corresponding rotating shaft, and the air inlet angle can be adjusted by setting the rotation angle.

[0049] The beneficial effects of the present application are:

[0050] The application provides a thermal management method and a thermal management system of a power battery. In the thermal management method, after the maximum temperature of a battery cell is obtained, if the maximum temperature of the battery cell is greater than a temperature threshold, the inlet air temperature is obtained, and then it is judged whether the difference between the maximum temperature of the battery cell and the inlet air temperature is greater than a difference threshold. If it is judged that the difference between the maximum temperature of the battery cell and the inlet air temperature is greater than the difference threshold, the minimum value of the air volume of the fan in a unit time is determined according to the determined minimum value, the gear of the fan is determined, and the fan is controlled to continuously operate according to the determined gear. In this way, the air inlet volume can be accurately controlled, and the energy consumption of the fan is reduced. In addition, before the fan is controlled to continuously operate according to the gear, it is necessary to judge whether the inlet air temperature sensor is effective. If it is judged that the inlet air temperature sensor is ineffective, the fault information of the inlet air temperature sensor is sent to the whole vehicle. In this way, the situation that the determined gear of the fan is inaccurate due to the inaccurate inlet air temperature obtained because the inlet air temperature sensor is ineffective, thereby affecting the cooling effect or increasing the energy consumption of the fan, can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 The flow chart of the thermal management method of the power battery of the embodiment 1 of the application;

[0052] Figure 2 The flow chart of one embodiment of the thermal management method of the power battery of the embodiment 1 of the application;

[0053] Figure 3 The explosion view of the power battery, the thermal management system of the power battery and the battery management system of the embodiment 2 of the application;

[0054] Figure 4 The front view of the power battery and the thermal management system of the power battery of the embodiment 2 of the application;

[0055] Figure 5 The structural block diagram of the thermal management system of the power battery and the battery management system of the embodiment 2 of the application;

[0056] Figure 6 The top view of the power battery and the thermal management system of the power battery of the embodiment 2 of the application;

[0057] Figure 7 The structural schematic view of the air door in the thermal management system of the power battery of the embodiment 2 of the application.

[0058] Explanation of reference signs:

[0059] 1: battery module; 101: battery cell;

[0060] 2: battery upper cover;

[0061] 3: battery base;

[0062] 4: air inlet channel;

[0063] 5: upper air duct;

[0064] 6: lower air duct;

[0065] 7: air outlet duct;

[0066] 8: air fan;

[0067] 9: air inlet temperature sensor;

[0068] 10: battery cell temperature sensor;

[0069] 11: battery management system;

[0070] 12: filter element;

[0071] 13: air door; 1301: air vane; 1302: rotating shaft. DETAILED DESCRIPTION

[0072] The present application will become fully understood from the detailed description given herein below and the accompanying drawings. The following description is merely illustrative of the present application and should not be taken in a limiting sense. While specific embodiments of the application are discussed, it is understood that various modifications, equivalents, substitutions and changes can be made without departing from the scope of the present application as defined by the appending claims. Unless otherwise expressly stated, it is intended that the descriptions herein shall include all equivalents that do not depart from the spirit and scope of the claimed application. It will be apparent that any described features can be combined in any combination. It is also to be understood that any feature described herein can be used and can be claimed in combination with any of the features described herein. Unless otherwise expressly stated, it is intended that the descriptions herein shall include all permutations of combination of each disclosed feature. It is intended that the following claims define and encompass any such combination or permutation of various embodiments.

[0073] It is to be understood that the same or equivalent parts are denoted by the same reference numerals throughout the figures. For the sake of clarity, not all reference numerals are shown in each figure.

[0074] In the description of the present embodiments, it should be noted that the terms "upper", "lower", "inner", "bottom", etc., indicate the positional or location relationship shown in the drawings, or the positional or location relationship when the product of the present application is used, and are merely for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be understood as limiting the present application.

[0075] The terms "first", "second", etc. are merely used to distinguish descriptions, and should not be understood as indicating or implying relative importance.

[0076] In the description of the embodiments, it should also be noted that unless specifically defined and limited, the terms "set", "connected", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments can be understood according to the specific circumstances.

[0077] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0078] Embodiment 1

[0079] The embodiments of the present application disclose a thermal management method of a power battery, the power battery comprising a plurality of battery cells. As shown in the figure, the thermal management method comprises the following steps: Figure 1

[0080] S1: acquiring state information of the power battery, and determining whether the power battery starts to work according to the state information of the power battery; the state information of the power battery comprises that the power battery starts to work and the power battery cell does not start to work.

[0081] If yes, step S2 is executed;

[0082] If no, step S1 is continuously executed.

[0083] S2: acquiring the highest temperature of the battery cell, and determining whether the highest temperature of the battery cell is greater than a temperature threshold; the way of acquiring the highest temperature of the battery cell is that a plurality of battery cell temperature sensors are arranged on the plurality of battery cells of the power battery, a plurality of battery cell temperatures are acquired through the plurality of battery cell temperature sensors, and the highest temperature in the plurality of battery cell temperatures is selected as the highest temperature of the battery cell.

[0084] If yes, step S3 is executed;

[0085] If no, step S2 is continuously executed.

[0086] S3: acquiring state information of a collection loop of an air inlet temperature sensor, and determining whether the air inlet temperature sensor is effective according to the state information of the collection loop; the air inlet temperature sensor is arranged at an air inlet of the power battery and is used for acquiring an air inlet temperature. The state information of the collection loop of the air inlet temperature sensor comprises short circuit, open circuit and normal of the collection loop.

[0087] If yes, step S4 is executed;

[0088] ​If no, then the fan is controlled to run at the lowest gear for a time t1, which is set according to the temperature threshold, the comfortable temperature of human body, the air conditioning cooling time when the vehicle is running, and other factors, and the fan is controlled to run at the highest gear for a time t1, and the fault information of the air inlet temperature sensor is sent to the vehicle to remind the customer to maintain. In the embodiment, the fan is arranged at the air outlet of the power battery, and the fan includes the highest gear, the lowest gear, the closed gear, and a plurality of intermediate gears between the highest gear and the lowest gear. The number of the intermediate gears can be one, two, three, or more, which can be set according to the requirement by the person skilled in the art, and the embodiment does not make a specific limitation.

[0089] S4: Obtain the air inlet temperature, and determine whether the difference between the maximum temperature of the battery cell and the air inlet temperature is greater than a difference threshold value;

[0090] If yes, step S5 is performed;

[0091] If no, the fan is controlled to run at the lowest gear for a time t2, and step S4 is continuously performed.

[0092] S5: Determine the minimum value of the air volume of the fan per unit time according to the following formula:

[0093]

[0094] Wherein, Q is the air volume of the fan per unit time, q is the heat generated by the current of the power battery per unit time, c is the specific heat capacity of air, p is the air density in the power battery, and AT1 is the absolute value of the difference between the maximum temperature of the battery cell and the air inlet temperature.

[0095] It should be noted that in order to achieve the effect of air cooling, the heat generated by the current of the power battery per unit time should be less than or equal to the heat that can be taken away by the current air volume of the fan, that is, q≤cρQΔT1, and therefore the minimum value of the air volume of the fan per unit time is the result calculated by the above formula.

[0096] Further, the heat generated by the current of the power battery per unit time can be calculated by the formula q=I 2 R, wherein R is the resistance in the power battery, which is generally a certain value, and I is the current of the power battery, which can be collected by setting a current sensor.

[0097] According to the determined minimum value of the air volume of the fan per unit time, the gear of the fan is determined in combination with the relationship between the air volume and the duty ratio corresponding to the gear, and the fan is controlled to run at the determined gear.

[0098] It should be noted that in the process of controlling the fan to continuously run according to the determined gear, the highest temperature of the battery cell is acquired in real time, and it is determined whether the highest temperature of the battery cell is greater than the temperature threshold value; if yes, the fan continues to run; if no, the fan is turned off. After the fan is turned off, step S2 is continued to be executed until the power battery ends work.

[0099] According to the technical scheme, after the highest temperature of the battery cell is acquired, if the highest temperature of the battery cell is greater than the temperature threshold value, after the air inlet temperature is acquired, it is determined whether the difference between the highest temperature of the battery cell and the air inlet temperature is greater than the difference threshold value; if the difference between the highest temperature of the battery cell and the air inlet temperature is greater than the difference threshold value, the gear of the fan is determined according to the minimum value of the air volume of the fan in a unit time, and the fan is controlled to continuously run according to the determined gear, so that the air inlet volume can be accurately controlled, and the energy consumption of the fan can be reduced. In addition, before the fan is controlled to continuously run according to the gear, it is necessary to determine whether the air inlet temperature sensor is effective; if the air inlet temperature sensor is determined to be ineffective, the fault information of the air inlet temperature sensor is sent to the whole vehicle, so that the situation that the determined gear of the fan is inaccurate due to the inaccurate air inlet temperature acquired because the air inlet temperature sensor is ineffective, thereby affecting the cooling effect or increasing the energy consumption of the fan, can be avoided.

[0100] According to one of the specific embodiments of the present application, according to the relationship between the minimum value of the air volume of the fan, the duty ratio corresponding to the gear and the air volume of the fan, the duty ratio corresponding to the minimum air volume in the air volume greater than the minimum value of the air volume of the fan is selected to determine the gear of the fan.

[0101] It should be noted that the relationship between the duty ratio corresponding to the gear and the air volume of the fan corresponding to different fans and power batteries is different; the relationship between the duty ratio corresponding to the gear and the air volume of the fan in one of the specific embodiments can be shown in Table 1; the greater the duty ratio corresponding to the gear, the greater the air volume of the fan, for example, the duty ratio corresponding to the gear is 90%, and the air volume that the fan can generate is 80m 3 / h; the duty ratio corresponding to the gear is 80%, and the air volume that the fan can generate is 70m 3 / h. The duty ratio corresponding to the minimum air volume in the air volume greater than the minimum value of the air volume of the fan is selected to determine the gear of the fan, so as to ensure that the heat that can be taken away by the fan corresponding to the air volume in a unit time is greater than the heat generated by the current of the power battery. For example, if the calculated minimum value of the air volume of the fan is 31m 3 / h, the air volume greater than the minimum value of the air volume of the fan in the relationship table between the duty ratio corresponding to the gear and the air volume of the fan includes 35m 3 / h, 40m 3 / h, 50m 3 / h, 60m 3 / h, etc., wherein the minimum value is 35m 3 / h, and the air volume is 35m 3The duty cycle corresponding to the h is 40%, and therefore the gear corresponding to the 40% duty cycle is selected as the determined gear of the fan.

[0102] Table 1

[0103] Duty cycle PWM / % Q1 / m 3 / h]] 10 20 20 25 30 30 40 35 50 40 60 50 70 60 80 70 90 80

[0104] According to the technical solution, the gear of the fan is determined according to the duty cycle corresponding to the minimum air volume in the air volumes greater than the minimum value of the determined air volume of the fan, so that the heat carried away by the air volume generated by the determined gear of the fan is greater than or equal to the heat generated by the current of the power battery, thereby ensuring the wind cooling effect, and the gear corresponding to the minimum air volume is selected on the basis of ensuring the wind cooling effect, so that the energy consumption of the fan is the lowest.

[0105] According to one of the specific embodiments of the present application, as shown in Figure 2 The heat management method further includes:

[0106] S6: During the operation of the fan, a plurality of cell temperatures are obtained, a maximum cell temperature difference is determined according to the plurality of cell temperatures, and it is determined whether the maximum cell temperature difference is greater than a cell temperature difference threshold value;

[0107] If yes, step S7 is performed;

[0108] If no, the fan continues to operate at the current gear, and step S6 is continuously performed.

[0109] S7: Gear information of the fan operation is obtained, and it is determined whether the fan is at the lowest gear according to the gear information;

[0110] If yes, the fan operates at the lowest gear. It should be noted that in the process of controlling the fan to operate at the lowest gear, the highest cell temperature is obtained in real time, and it is determined whether the highest cell temperature is greater than a temperature threshold value. If yes, the fan continues to operate; if no, the fan is turned off. After the fan is turned off, step S2 is continuously performed until the power battery ends the work.

[0111] If no, the fan is controlled to run at a lower gear for a time t3, and step S6 is continued. It should be noted that in the present embodiment, if the maximum cell temperature difference is greater than the cell temperature difference threshold and the fan is not at the lowest gear, the fan can be controlled to run at a gear lower than the current gear by one. For example, if in the present embodiment, the relationship between the gear and the duty cycle corresponding to the fan air volume is shown in Table 1, if the fan is currently running at the gear corresponding to a 40% duty cycle, the fan will run at the gear corresponding to a 30% duty cycle after being lowered by one gear. The fan can also be controlled to run at a gear lower than the current gear by two. For example, if the fan is currently running at the gear corresponding to a 40% duty cycle, the fan will run at the gear corresponding to a 20% duty cycle after being lowered by two gears. The fan can also be controlled to run at a gear lower than the current gear by three, four, or even more gears, which can be set according to actual needs by those skilled in the art, and the present embodiment does not make specific limitations. If the difference between the current gear of the fan and the lowest gear is less than the required number of gears to be lowered, the fan is controlled to run at the lowest gear. For example, if the maximum cell temperature difference is greater than the cell temperature difference threshold and the fan is not at the lowest gear, the fan is controlled to run at a gear lower than the current gear by three, and the fan is currently running at the gear corresponding to a 30% duty cycle, the fan is controlled to run at the gear corresponding to a 10% duty cycle, i.e., at the lowest gear.

[0112] With the above technical solution, during the operation of the fan, a plurality of cell temperatures are obtained, the maximum cell temperature difference is determined according to the plurality of cell temperatures, and it is determined whether the maximum cell temperature difference is greater than the cell temperature difference threshold. If it is determined that the maximum cell temperature difference is greater than the cell temperature difference threshold and the fan is not at the lowest gear, the fan is controlled to run at a lower gear. This can improve the consistency of the cells and prolong the service life of the power battery.

[0113] According to one of the specific embodiments of the present application, the temperature threshold value ranges from 28 to 32℃, and the temperature threshold value can be 28℃, 29℃, 30℃, 31℃, or 32℃, or other temperature values between 28 and 32℃, which can be set by those skilled in the art according to actual conditions, and the present embodiment does not specifically limit this. The difference threshold value ranges from 1 to 2℃, and the difference threshold value can be 1℃ or 2℃, or other temperature values between 1 and 2℃, which can be set by those skilled in the art according to actual conditions, and the present embodiment does not specifically limit this. The cell temperature difference threshold value is 10℃, and those skilled in the art can also set other temperature values according to actual conditions. The time t1 ranges from 1 to 5 min, which can be calibrated by the air conditioning refrigeration performance of the whole vehicle development stage, and the time t1 can be 1 min, 2 min, 3 min, 4 min, or 5 min, or other values between 1 and 5 min, which can be set by those skilled in the art according to actual conditions, and the present embodiment does not specifically limit this. The time t2 is 30 s, and those skilled in the art can also set other values according to actual conditions. The time t3 is 20 s, and those skilled in the art can also set other values according to actual conditions.

[0114] According to one of the specific embodiments of the present application, in step S3, determining whether the inlet air temperature sensor is valid according to the state information of the acquisition circuit includes: if the acquisition circuit is an open circuit or a short circuit, determining that the inlet air temperature sensor is invalid; otherwise, the inlet air temperature sensor is valid, that is, the acquisition circuit is normal, and the inlet air temperature sensor is valid.

[0115] By using the above technical solution, if the acquisition circuit is an open circuit or a short circuit, it is determined that the inlet air temperature sensor is invalid; otherwise, the inlet air temperature sensor is valid, so that the method for determining whether the inlet air temperature sensor is valid is simple and convenient.

[0116] According to one of the specific embodiments of the present application, during the operation of the fan, the gear information of the fan operation is acquired in real time, the gear information includes the gear of the fan being operated, and whether the fan operates according to the determined gear is determined according to the gear information and the determined gear; if yes, the fan continues to operate according to the determined gear; if no, the fan failure information is sent to the whole vehicle to remind the customer to repair the fan, and the fan is controlled to operate according to the highest gear, even if the fan cannot operate at the highest gear.

[0117] By means of the technical scheme, the gear information of the fan in operation is acquired in real time, and whether the fan operates according to the determined gear is judged according to the gear information and the determined gear, that is, whether the current operating gear of the fan is consistent with the determined gear, if it is judged that the fan does not operate according to the determined gear, the fault information of the fan is sent to the whole vehicle, and the fan is controlled to operate continuously according to the highest gear, so that the situation that the fan does not operate according to the determined gear and affects the cooling effect of the power battery or increases the energy consumption of the fan can be avoided.

[0118] The beneficial effects of the present application are:

[0119] The present application provides a thermal management method of a power battery, after obtaining the maximum temperature of the battery cell, if the maximum temperature of the battery cell is greater than the temperature threshold, after obtaining the inlet air temperature, it is judged whether the difference between the maximum temperature of the battery cell and the inlet air temperature is greater than the difference threshold, if it is judged that the difference between the maximum temperature of the battery cell and the inlet air temperature is greater than the difference threshold, the minimum value of the air volume of the fan in a unit time is determined according to the determined gear, and the fan is controlled to operate continuously according to the determined gear, so that the air inlet amount can be accurately controlled, and the energy consumption of the fan can be reduced. In addition, before controlling the fan to operate continuously according to the gear, it is necessary to judge whether the inlet air temperature sensor is effective, if it is judged that the inlet air temperature sensor is ineffective, the fault information of the inlet air temperature sensor is sent to the whole vehicle, so that the situation that the determined fan gear is inaccurate due to the inaccurate inlet air temperature obtained if the inlet air temperature sensor is ineffective, thereby affecting the cooling effect or increasing the energy consumption of the fan, can be avoided.

[0120] Embodiment 2

[0121] The present application discloses a thermal management system of a power battery, which is used to execute the above-mentioned thermal management method of the power battery, as shown in Figure 3 and Figure 4 The power battery comprises a battery module 1, a battery upper cover 2 and a battery base 3; one end of the battery upper cover 2 is opened, as shown in Figure 3 The bottom end of the battery upper cover 2 is opened, and the battery module 1 is arranged inside the battery upper cover 2; the opposite sides of the battery upper cover 2 are respectively provided with first and second through holes, which can be arranged on the left and right sides of the battery upper cover 2 as shown in Figure 3 The upper and lower sides and the front and rear sides of the battery upper cover 2, and the present embodiment does not make specific limitation thereon. As shown in Figure 4 The battery upper cover 2 and the battery base 3 are connected together to form a closed environment, which is isolated from external dust, water and the like. The battery module 1 comprises a plurality of spaced battery cells 101, the number of the battery cells 101 can be two, three, four or even more, and the distance between the adjacent two battery cells 101 can be equal or unequal, and the present embodiment does not make specific limitation thereon.

[0122] AsFigure 3 As shown, the thermal management system comprises an air inlet channel 4, an upper air channel 5, a lower air channel 6, an air outlet channel 7, a fan 8, an air inlet temperature sensor 9, and a plurality of battery cell temperature sensors 10, the number of which is at least three, which can be three, four, five or even more, and the present embodiment does not make specific limitations thereon.

[0123] As shown in Figure 5 , the fan 8, the air inlet temperature sensor 9, and each battery cell temperature sensor 10 are respectively connected with a battery management system 11. It should be noted that the battery management system 11 comprises a processor, and the battery management system 11 and the fan 8 are connected through transmission of a PWM signal to realize the functions of controlling and detecting the gear of the fan 8.

[0124] As shown in Figure 4 , the air inlet channel 4 and the air outlet channel 7 are respectively arranged on opposite sides of the battery upper cover 2, which can be arranged on the left and right sides of the battery upper cover 2 as shown in Figure 4 , and can also be arranged on the upper and lower sides or the front and rear sides of the battery upper cover 2, and the present embodiment does not make specific limitations thereon. The upper air channel 5 and the lower air channel 6 are arranged inside the battery upper cover 2 and are respectively arranged on opposite sides of the battery module 1, which can be arranged on the upper and lower sides of the battery module 1 as shown in Figure 4 . The lower air channel 6 can be arranged separately from the battery base 3, or can be integrally arranged with the battery base 3 as shown in Figure 3 . One end of the air inlet channel 4 penetrates through a first through hole and is connected with one end of the upper air channel 5, and one end of the air outlet channel 7 penetrates through a second through hole and is connected with one end of the lower air channel 6. The upper air channel 5 is made of a lightweight V0-grade flame-retardant material, which can be plastic, and is fixedly connected with one side surface of the battery module 1, so that the upper air channel 5 can not only realize the basic function of guiding air, but also realize the purposes of preventing heat runaway diffusion and lightweight of the power battery. It should be noted that the arrows shown in Figure 4 and Figure 6 indicate the flow direction of the air entering the air inlet channel 4.

[0125] As shown in Figure 3 , Figure 4 and Figure 6 , the fan 8 is arranged at one end of the air outlet channel 7 away from the battery upper cover 2; the air inlet temperature sensor 9 is arranged on the air inlet channel 4; and the plurality of battery cell temperature sensors 10 are all arranged on the battery cell 101 as shown in Figure 3As shown, the battery module 1 is provided with the battery cell temperature sensor 10 on both ends of the battery cell 101 and the middle battery cell 101, and the battery cell temperature sensor 10 can be provided on other positions of the battery cell 101 or not provided, which is not limited in the art. The battery management system 11 is arranged in the power battery, specifically arranged in the inside of the battery upper cover 2, and connected with the power battery, which can be detachable fixed connection or non-detachable fixed connection, and the detachable fixed connection can be clamping, threaded connection, etc., and the non-detachable fixed connection can be adhesive, welding, etc.

[0126] According to the above technical scheme, the fan 8, the air inlet temperature sensor 9, and each battery cell temperature sensor 10 are connected with the battery management system 11, the air inlet temperature sensor 9 obtains the air inlet temperature in real time and sends it to the battery management system 11, the plurality of battery cell temperature sensors 10 obtain the plurality of battery cell temperatures in real time and send them to the battery management system 11, the battery management system 11 receives the plurality of battery cell temperatures to determine the maximum battery cell temperature and the maximum battery cell temperature difference, the battery management system 11 receives the air inlet temperature and determines the gear of the fan 8 according to the air inlet temperature, the maximum battery cell temperature, and the maximum battery cell temperature difference according to the above control method of the power battery, and controls the fan 8 to run according to the determined gear, so that the air inlet amount can be accurately controlled and the energy consumption of the fan 8 can be reduced. In addition, during the operation of the fan 8, the fan 8 sends the running gear information to the battery management system 11 in real time, the battery management system 11 receives the running gear information of the fan 8, and judges whether the fan 8 runs according to the determined gear according to the gear information and the determined gear. If it is determined that the fan 8 does not run according to the determined gear, the battery management system 11 sends the fault information of the fan 8 to the whole vehicle to remind the customer to repair the fan 8.

[0127] According to one of the specific embodiments of the present application, as shown in Figure 4 and Figure 6 As shown, the thermal management system further comprises a filter element 12, which is arranged at the inlet of the air inlet duct 4 and detachably connected with the air inlet duct 4. In the present embodiment, the detachable connection mode can be clamping, threaded connection, etc., which is not limited in the present embodiment.

[0128] According to the above technical scheme, by arranging the filter element 12 at the inlet of the air inlet duct 4, on the one hand, the cleanliness of the surface of the battery cell 101 can be improved, and the efficiency of the thermal management performance of the power battery in the whole life cycle can be maintained; on the other hand, the probability of impurity accumulation in the power battery can be reduced, and the risk of thermal runaway of the power battery caused by short circuit due to impurities can be reduced.

[0129] According to one of the specific embodiments of the present application, as shown in Figure 4As shown, the thermal management system further comprises a damper 13, which is arranged at one end of the air inlet duct 4 close to the battery module 1 and detachably connected with the air inlet duct 4. In the embodiment, the detachable connection can be clamping, threaded connection, etc.

[0130] With the above technical solution, once thermal runaway occurs in the power battery, the damper 13 is closed by the large air pressure generated by the thermal runaway, which can not only reduce the oxygen entering the power battery to assist combustion, but also prevent the harmful gas in the power battery from spreading to the passenger compartment.

[0131] According to one of the specific embodiments of the present application, as shown in Figure 7 As shown, the damper 13 comprises a plurality of vanes 1301 and a plurality of shafts 1302, both ends of each shaft 1302 are connected to opposite sides of the damper 13, and each vane 1301 is rotatable relative to a corresponding shaft 1302. The number of vanes 1301 and shafts 1302 can be one, two, three or more, and the present embodiment does not make specific limitations thereon. In the embodiment, the angle of rotation of each vane 1301 relative to the corresponding shaft 1302 can be 0-90°.

[0132] With the above technical solution, each vane 1301 is rotatable relative to the corresponding shaft 1302, and the air inlet angle can be adjusted by setting the rotation angle.

[0133] Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing is a further detailed description of the application in connection with specific embodiments, and the specific embodiments do not limit the application. Those skilled in the art can make various changes in form and details without departing from the spirit and scope of the application, including making a number of simple deductions or substitutions.

Claims

1. A method for thermal management of a power battery, the power battery comprising a plurality of battery cells; characterized in that, The thermal management method comprises the following steps: S1: obtaining state information of the power battery, and determining whether the power battery starts to work according to the state information of the power battery; If yes, step S2 is executed; If no, the step S1 is continuously executed; S2: obtaining the maximum temperature of the battery cell, and determining whether the maximum temperature of the battery cell is greater than a temperature threshold value; If yes, step S3 is executed; If no, the step S2 is continuously executed; S3: obtaining state information of a collection loop of an air inlet temperature sensor, and determining whether the air inlet temperature sensor is effective according to the state information of the collection loop; the air inlet temperature sensor is arranged at an air inlet of the power battery and is used for obtaining an air inlet temperature; If yes, step S4 is executed; If no, the fan is controlled to continuously run at the lowest gear for a time t1, then the fan is controlled to continuously run at the highest gear, and fault information of the air inlet temperature sensor is sent to a whole vehicle; the fan is arranged at an air outlet of the power battery; S4: obtaining the air inlet temperature, and determining whether a difference between the maximum temperature of the battery cell and the air inlet temperature is greater than a difference threshold value; If yes, step S5 is executed; If no, the fan is controlled to continuously run at the lowest gear for a time t2, and the step S4 is continuously executed; S5: determining a minimum value of the fan air volume per unit time according to the following formula: Wherein, Q is the fan air volume per unit time, q is heat generated by the current of the power battery per unit time, c is air specific heat capacity, p is air density in the power battery, and AT1 is an absolute value of the difference between the maximum temperature of the battery cell and the air inlet temperature; The gear of the fan is determined according to the minimum value of the fan air volume per unit time, and the fan is controlled to continuously run at the determined gear.

2. The method of thermal management of a power battery of claim 1, wherein, According to the relationship between the minimum value of the fan air volume, the duty cycle corresponding to the gear of the fan air volume, and the fan air volume, the duty cycle corresponding to the minimum air volume in the air volume greater than the minimum value of the fan air volume is selected to determine the gear of the fan.

3. The method of thermal management of a power cell of claim 2, wherein, The thermal management method further comprises: S6: during the operation of the fan, a plurality of battery cell temperatures are obtained, a maximum battery cell temperature difference is determined according to the plurality of battery cell temperatures, and it is determined whether the maximum battery cell temperature difference is greater than a battery cell temperature difference threshold value; If yes, step S7 is executed; If no, the fan is controlled to continuously run at the current gear, and the step S6 is continuously executed; S7: obtaining gear information of the fan operation, and determining whether the fan is at the lowest gear according to the gear information; If yes, the fan is controlled to run at the lowest gear; If no, the fan is controlled to run at a lower gear for a time t3, and the step S6 is continuously executed.

4. The method of thermal management of a power cell of claim 3, wherein, The temperature threshold value ranges from 28 to 32 DEG C; the difference threshold value ranges from 1 to 2 DEG C; and the battery cell temperature difference threshold value is 10 DEG C; The time t1 ranges from 1 to 5 min; the time t2 is 30 s; and the time t3 is 20 s.

5. The method of thermal management of a power cell of claim 4, wherein, In the step S3, whether the air inlet temperature sensor is effective is determined according to the state information of the collection loop. If the collection circuit is open or short, it is determined that the inlet air temperature sensor is invalid; otherwise, the inlet air temperature sensor is valid.

6. The thermal management method of a power battery according to any one of claims 1-5, characterized in that, During the operation of the fan, the gear information of the fan operation is acquired in real time, and it is determined whether the fan operates according to the determined gear according to the gear information and the determined gear; If yes, the fan continues to operate according to the determined gear; If no, the fault information of the fan is sent to the whole vehicle, and the fan is controlled to operate according to the highest gear.

7. A thermal management system for a power battery, characterized in that The application relates to a thermal management method for a power battery, the power battery comprising a battery module, a battery upper cover and a battery base; wherein One end of the battery upper cover is open, and the battery module is arranged inside the battery upper cover; opposite sides of the battery upper cover are respectively provided with first and second through holes; The battery module comprises a plurality of spaced battery cells; The thermal management system comprises an air inlet channel, an upper air channel, a lower air channel, an air outlet channel, a fan, an inlet air temperature sensor and a plurality of battery cell temperature sensors; the fan, the inlet air temperature sensor and each battery cell temperature sensor are connected with a battery management system; wherein The air inlet channel and the air outlet channel are respectively arranged on opposite sides of the battery upper cover; The upper air channel and the lower air channel are arranged inside the battery upper cover and on opposite sides of the battery module respectively; One end of the air inlet channel penetrates through the first through hole and is connected with one end of the upper air channel, and one end of the air outlet channel penetrates through the second through hole and is connected with one end of the lower air channel; The fan is arranged at one end of the air outlet channel away from the battery upper cover; The inlet air temperature sensor is arranged on the air inlet channel; The battery cell temperature sensors are arranged on the battery cells, and the battery cell temperature sensors are arranged on the battery cells at both ends and in the middle of the battery module; The battery management system is arranged inside the power battery.

8. The thermal management system of a power battery according to claim 7, wherein, The thermal management system further comprises a filter element, the filter element is arranged at the inlet of the air inlet channel and detachably connected with the air inlet channel.

9. The thermal management system of a power battery according to claim 7 or 8, characterized in that, The thermal management system further comprises an air door, the air door is arranged at one end of the air inlet channel close to the battery module and detachably connected with the air inlet channel.

10. The thermal management system of a power battery according to claim 9, wherein, The air door comprises a plurality of air vanes and a plurality of rotating shafts, both ends of each rotating shaft are connected to opposite sides of the air door, and each air vane is rotatable relative to the corresponding rotating shaft.

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