Safety protection method and system for multi-level battery system

Abstract

The present invention discloses a safety protection method and system for a multi-level battery system, and relates to the technical field of battery safety protection, including: obtaining a battery tolerance range and a battery limit temperature under different external ambient temperatures by a temperature analysis method; obtaining current data in a circuit connected to a cooling system, and setting a tolerance current range and a limit current of the cooling system based on the current data; setting a first-layer power-off protection, a second-layer buffer protection and a third-layer cooling protection for the battery system; the present invention is used to solve the problem that in the prior art, there is a lack of improvements in battery cooling in terms of multi-level safety protection for batteries, which results in an inability to determine which cooling method to use based on the overheating of the battery, causing problems of circuit safety and resource waste.

Description

Technical Field

[0001] The present invention relates to the technical field of battery safety protection, and in particular to a safety protection method and system for a multi-level battery system. Background Art

[0002] With the rapid popularization of civilian lithium-ion batteries and the large-scale application of electric vehicles in the future, battery safety issues have become increasingly prominent; organic electrolytes are extremely flammable substances; battery overheating, overcharging and overdischarging may cause electrolyte combustion and even battery explosion; therefore, battery safety protection issues must be considered when designing batteries to prevent a series of hazards caused by inadequate battery safety protection.

[0003] Existing methods for battery safety protection are usually improvements in battery temperature monitoring. For example, in the patent with publication number CN114824520A, a vehicle battery protection method, storage medium, device and vehicle are disclosed. The scheme accurately determines the minimum temperature corresponding to the location of the vehicle by combining the forecast temperature of the location of the vehicle and the ambient temperature of the vehicle, and timely adjusts the battery power according to the minimum temperature, thereby timely adjusting the freezing point temperature of the battery to reduce the risk of battery freezing. However, in the existing methods for battery cooling, there is a lack of improved methods for multi-level safety protection of the battery in terms of cooling. When the battery overheats during operation, it is impossible to determine which cooling method to use based on the overheating of the battery, so that when the battery is at a high temperature, the cooling system is started to cool the battery module, causing the circuit of the cooling system to burn out and cause a series of hazards, or the cooling system is started when the battery is at a relatively low temperature, resulting in a waste of resources. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems in the prior art to a certain extent. By proposing a multi-level battery system safety protection method and system, the present invention is used to solve the problem that in the prior art, there is a lack of a method for multi-level safety protection of the battery in terms of cooling. When the battery overheats during operation, it is impossible to determine which cooling method to use based on the overheating of the battery. As a result, the cooling system is started when the battery is at a high temperature and temperature damage is caused to the circuit of the cooling system, which will cause damage to the circuit of the cooling system, or the cooling system is started when the battery is at a relatively low temperature, resulting in a waste of resources.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a multi-level battery system safety protection method, wherein the battery system includes a battery management system, a battery module and a cooling system, and comprises the following steps:

[0006] The battery system is placed in different external temperatures for operation, and the battery management system is used to monitor the temperature and charging rate of the battery module during operation. The temperature analysis method is used to obtain the battery tolerance range and battery limit temperature under different external temperatures;

[0007] When the battery module is at different external temperatures and the battery module is at a battery tolerance range and a battery limit temperature, current data in a circuit connected to the cooling system is obtained, and a tolerance current range and a limit current of the cooling system are set based on the current data;

[0008] The battery system is provided with a first layer of power-off protection, a second layer of buffer protection and a third layer of cooling protection at different external temperatures.

[0009] Furthermore, the battery system is placed in different external temperatures for operation, and the battery management system is used to monitor the temperature and charging rate of the battery module during operation. The temperature analysis method is used to obtain the battery tolerance range and battery limit temperature under different external temperatures, including:

[0010] Obtain the maximum temperature and the minimum temperature of the external environment when the battery system is operating normally, and record them as the external upper limit temperature and the external lower limit temperature;

[0011] The temperature between the lower limit temperature and the upper limit temperature is evenly divided into J segments, and recorded as the outer temperature segment 1 to the outer temperature segment J in order from low to high, wherein the lowest temperature in the outer temperature segment 1 is the lower limit temperature of the outer temperature, and the highest temperature in the outer temperature segment J is the upper limit temperature of the outer temperature;

[0012] The battery systems are placed in environments with temperatures ranging from ambient temperature segment 1 to ambient temperature segment J, and the temperature analysis method is used to analyze the battery systems in different temperature environments in turn and record various data in the battery systems.

[0013] Further, the temperature analysis method includes:

[0014] For a temperature environment in any one of the external temperature segments J1 from the external temperature segment 1 to the external temperature segment J, the battery system is charged until the battery module is fully charged and the battery management system is used to obtain the temperature of the battery module in real time;

[0015] Establish a plane rectangular coordinate system, recorded as a battery temperature coordinate system, wherein the unit of the X-axis of the battery temperature coordinate system is time, and the unit of the Y-axis of the battery temperature coordinate system is temperature;

[0016] The temperature of the battery module obtained by the battery management system is marked in the form of a curve in the battery temperature coordinate system, and the marked curve is recorded as a temperature change curve, wherein the X-axis coordinate corresponding to the leftmost point of the temperature change curve is the coordinate origin;

[0017] Use the battery management system to obtain the charging rate of the battery module in real time after charging starts. Record the time when the charging rate continues to rise after charging starts as the charging start time, record the time when the charging rate starts to decrease as the charging reduction time, obtain the percentage of power in the battery module during the charging reduction time, and record it as the rate reduction percentage. Obtain the percentage of power in the battery module when the charging protection of the battery module is triggered under normal charging conditions, and record it as the standard reduction percentage.

[0018] Furthermore, the temperature analysis method also includes:

[0019] When the rate reduction percentage is greater than or equal to the standard reduction percentage, the point with the largest ordinate in the temperature change curve is recorded as the limit temperature point, the ordinate corresponding to the limit temperature point is marked as the battery limit temperature, and the interval formed by the lowest point of the ordinate and the highest point of the ordinate in the area other than the limit temperature point in the temperature change curve is recorded as the battery tolerance interval;

[0020] When the rate reduction percentage is less than the standard reduction percentage, the point corresponding to the charging reduction time on the temperature change curve is recorded as the tolerance starting point, the point where the percentage of the battery module power is the standard reduction percentage is recorded as the tolerance end point, the curve between the tolerance starting point and the tolerance end point is recorded as the tolerance curve, the curve formed by the lowest point of the ordinate and the highest point of the ordinate in the tolerance curve is recorded as the battery tolerance range, the point with the largest ordinate in the tolerance curve is recorded as the limit temperature point, and the ordinate corresponding to the limit temperature point is marked as the battery limit temperature;

[0021] The battery tolerance range and the battery limit temperature when the battery system is in the temperature environment of all external temperature ranges are obtained respectively.

[0022] Further, when the battery module is at different external temperatures and the battery module is at a battery tolerance range and a battery limit temperature, obtaining current data in a circuit connected to the cooling system, and setting a tolerance current range and a limit current of the cooling system based on the current data includes:

[0023] The maximum instantaneous current allowed to pass through the circuit connected to the battery system is recorded as the instantaneous MAX; the shortest time that the circuit can continue to operate when the instantaneous current in the circuit connected to the battery system is the instantaneous MAX is recorded as the cooling buffer time;

[0024] For any external temperature segment J1 from external temperature segment 1 to external temperature segment J, obtain the interval corresponding to the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of external temperature segment J1 and the temperature of the battery module is in the battery tolerance range, which is recorded as the tolerance current interval.

[0025] Further, when the battery module is at different external temperatures and the battery module is at a battery tolerance range and a battery limit temperature, obtaining current data in a circuit connected to the cooling system, and setting a tolerance current range and a limit current of the cooling system based on the current data also includes:

[0026] Obtain the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of the external temperature segment J1 and the temperature of the battery module is the battery limit temperature, and record it as the limit current;

[0027] When the limiting current is less than or equal to the instantaneous MAX, the external temperature segment J1 is recorded as the stable operating temperature segment of the battery system;

[0028] When the limit current is greater than the instantaneous MAX, the point in the tolerance current interval that is equal to the instantaneous MAX is recorded as the cooling limit point, and the temperature in the battery tolerance interval corresponding to the instantaneous current being the cooling limit point is recorded as the cooling termination temperature;

[0029] Obtain the tolerance current curves and limit currents corresponding to all external temperature segments; obtain the cooling termination temperatures corresponding to all external temperature segments that are not recorded as stable operating temperature segments.

[0030] Furthermore, the first-layer power-off protection, the second-layer buffer protection and the third-layer cooling protection of the battery system set at different external temperatures include:

[0031] Set up a layer of power-off protection;

[0032] The first-layer power-off protection is as follows: obtaining the external temperature when the battery system is running, and obtaining the external temperature segment in which the external temperature when the battery system is running is located, which is recorded as the real-time temperature segment;

[0033] When the real-time temperature segment contains the cooling termination temperature, the temperature of the battery module is obtained in real time during the operation of the battery system. When the temperature of the battery module is lower than the cooling termination temperature, the cooling system is used to cool the battery module; when the temperature of the battery module is greater than or equal to the cooling termination temperature, the cooling system and the battery module are powered off.

[0034] Furthermore, the first-layer power-off protection, the second-layer buffer protection and the third-layer cooling protection of the battery system set at different external temperatures also include:

[0035] Set up a second layer of buffer protection;

[0036] The second-level buffer protection is: when the real-time temperature segment does not contain the cooling termination temperature, the cooling system is continuously used to cool the battery module during the operation of the battery system, and the instantaneous current in the circuit connected to the cooling system is obtained in real time, which is recorded as the real-time instantaneous current; when the real-time instantaneous current is greater than the instantaneous MAX, the battery module is powered off, and then the cooling system is powered off after the cooling buffer time.

[0037] Furthermore, the first-layer power-off protection, the second-layer buffer protection and the third-layer cooling protection of the battery system set at different external temperatures also include:

[0038] Set up three layers of cooling protection;

[0039] The three-level cooling protection is: when the real-time temperature segment does not contain the cooling termination temperature and the real-time instantaneous current is always less than or equal to the instantaneous MAX during the operation of the battery system, the cooling system is used to continuously cool the battery module.

[0040] In a second aspect, the present invention also provides a safety protection system for a multi-level battery system, including a temperature analysis module, a cooling analysis module, and a multi-level protection setting module;

[0041] The temperature analysis module is used to operate the battery system at different external temperatures, and use the battery management system to monitor the temperature and charging rate of the battery module during operation, and use the temperature analysis method to obtain the battery tolerance range and battery limit temperature at different external temperatures;

[0042] The cooling analysis module is used to obtain current data in the circuit connected to the cooling system when the battery module is at different external temperatures and the battery module is at the battery tolerance range and the battery limit temperature, and to set the tolerance current range and the limit current of the cooling system based on the current data;

[0043] The multi-layer protection setting module is used to set a first-layer power-off protection, a second-layer buffer protection and a third-layer cooling protection for the battery system under different external temperatures.

[0044] Beneficial effects of the present invention: The present invention places the battery system to operate at different external temperatures, uses a battery management system to monitor the temperature and charging rate of the battery module during operation, and uses a temperature analysis method to obtain the battery tolerance range and battery limit temperature at different external temperatures. The advantage of this is that by obtaining the battery limit temperature and battery tolerance range, the maximum temperature that the battery module can withstand when it is heated and the temperature range in which it can operate normally can be obtained, which is helpful in setting the start-up and cut-off conditions of the battery module in subsequent analysis, thereby fully cooling the battery system while protecting the circuit of the cooling system from being burned;

[0045] The present invention also obtains current data in the circuit connected to the cooling system when the battery module is at different external temperatures and the battery module is in the battery tolerance range and the battery limit temperature, and sets the tolerance current range and the limit current of the cooling system based on the current data, and finally sets a first layer of power-off protection, a second layer of buffer protection and a third layer of cooling protection for the battery system at different external temperatures. The advantage of this is that by setting the tolerance current range and the limit current, the cut-off condition of the circuit connected to the cooling system can be set, so that the circuit can be cut off in time when the temperature of the battery module can affect the circuit, thereby preventing a series of hazards caused by the burning of the cooling system circuit.

[0046] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a functional block diagram of the system of the present invention;

[0048] Figure 2 A schematic diagram of the steps of the method of the present invention;

[0049] Figure 3 It is a structural schematic diagram of the battery system of the present invention;

[0050] Figure 4 It is a schematic diagram of the temperature variation curve of the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Example 1, please refer to Figure 1 As shown, in the first aspect, the present application provides a multi-level battery system safety protection system, including a temperature analysis module, a cooling analysis module and a multi-layer protection setting module.

[0053] See also Figure 3As shown, the battery system includes a battery management system, a battery module and a cooling system. The temperature analysis module is used to place the battery system for operation at different external temperatures, and use the battery management system to monitor the temperature and charging rate of the battery module during operation. The temperature analysis method is used to obtain the battery tolerance range and battery limit temperature at different external temperatures.

[0054] The temperature analysis module is configured with a battery module temperature analysis strategy, which includes:

[0055] The maximum temperature and the minimum temperature of the external environment when the battery system is operating normally are obtained, and recorded as the external upper limit temperature and the external lower limit temperature.

[0056] The temperature between the lower limit temperature and the upper limit temperature is evenly divided into J sections, and is recorded from low to high as the external temperature section 1 to the external temperature section J, wherein the lowest temperature in the external temperature section 1 is the lower limit temperature of the external environment, and the highest temperature in the external temperature section J is the upper limit temperature of the external environment.

[0057] In the specific implementation process, the value of J can be specifically set according to the difference between the external upper limit temperature and the external lower limit temperature in the actual situation. When the difference between the external upper limit temperature and the external lower limit temperature is large, the value of J can be increased. When the difference between the external upper limit temperature and the external lower limit temperature is small, the value of J can be reduced. In this embodiment, the value of J is set to 5; for example, in a data processing, the external upper limit temperature is detected to be 30°C and the external lower limit temperature is 5°C, then the external temperature segment 1 to the external temperature segment 5 are 5°C to 10°C, 10°C to 15°C, 15°C to 20°C, 20°C to 25°C and 25°C to 30°C respectively.

[0058] The battery systems are placed in environments with temperatures ranging from ambient temperature segment 1 to ambient temperature segment J, and the temperature analysis method is used to analyze the battery systems in different temperature environments in turn and record various data in the battery systems.

[0059] The temperature analysis method includes: for a temperature environment in any one of the external temperature segments J1 from the external temperature segment 1 to the external temperature segment J, charging the battery system until the battery module is fully charged and using the battery management system to obtain the temperature of the battery module in real time.

[0060] A plane rectangular coordinate system is established, which is recorded as a battery temperature coordinate system, wherein the unit of the X-axis of the battery temperature coordinate system is time, and the unit of the Y-axis of the battery temperature coordinate system is temperature.

[0061] In the battery temperature coordinate system, the temperature of the battery module obtained by the battery management system is marked in the form of a curve, and the marked curve is recorded as a temperature change curve, wherein the X-axis coordinate corresponding to the leftmost point of the temperature change curve is the coordinate origin.

[0062] See also Figure 4 As shown, the curve corresponding to DD1 is the temperature change curve, the point corresponding to DD2 is the charging reduction time, and the power percentage in the battery module at time DD3 is the standard reduction percentage. Through analysis, it can be obtained that the point corresponding to DD5 is the tolerance starting point, the point corresponding to DD4 is the tolerance end point, the curve between DD4 and DD5 is the tolerance curve, the temperature range corresponding to DD6 to DD7 is the battery tolerance range, and the point corresponding to DD8 is the extreme temperature point.

[0063] Use the battery management system to obtain the charging rate of the battery module in real time after charging starts. Record the time when the charging rate continues to rise after charging starts as the charging start time, record the time when the charging rate starts to decrease as the charging reduction time, obtain the percentage of power in the battery module during the charging reduction time, and record it as the rate reduction percentage. Obtain the percentage of power in the battery module when the charging protection of the battery module is triggered under normal charging conditions, and record it as the standard reduction percentage.

[0064] In the specific implementation process, during the actual charging process of the battery, when the power of the battery module is higher than a certain percentage, the battery system will reduce the charging efficiency to protect the battery system to have a longer service life. Therefore, the above percentage is recorded as the standard reduction percentage, and compared with the percentage when the charging rate of the battery module is reduced due to the influence of external temperature during the actual charging process. Analysis, and then whether the charging rate of the battery module is reduced due to the influence of external temperature is obtained. In this embodiment, the standard reduction percentage is set to 80%.

[0065] The temperature analysis method also includes: when the rate reduction percentage is greater than or equal to the standard reduction percentage, the point with the largest ordinate in the temperature change curve is recorded as the extreme temperature point, the ordinate corresponding to the extreme temperature point is marked as the battery extreme temperature, and the interval formed by the lowest point of the ordinate and the highest point of the ordinate in the area other than the extreme temperature point in the temperature change curve is recorded as the battery tolerance interval.

[0066] When the rate reduction percentage is less than the standard reduction percentage, the point on the temperature change curve whose horizontal axis corresponds to the charging reduction time is recorded as the tolerance starting point, the point whose percentage of the battery module's power is the standard reduction percentage is recorded as the tolerance end point, the curve between the tolerance starting point and the tolerance end point is recorded as the tolerance curve, the curve formed by the lowest point of the vertical axis and the highest point of the vertical axis in the tolerance curve is recorded as the battery tolerance range, the point with the largest vertical axis in the tolerance curve is recorded as the extreme temperature point, and the vertical axis corresponding to the extreme temperature point is marked as the battery extreme temperature.

[0067] When the rate reduction percentage is less than the standard reduction percentage, it means that the battery module is affected by external factors, resulting in a rate reduction before the power in the charging module reaches the standard reduction percentage. Therefore, the time between the charging reduction time and the time when the percentage of power in the battery module is the standard reduction percentage should be analyzed. In the obtained tolerance curve, the temperature range corresponding to the battery tolerance range is the temperature range in which the battery is affected by external temperature and the charging rate is reduced. The battery limit temperature is the maximum temperature that the battery can withstand when affected by external temperature. Therefore, the battery tolerance range and the battery limit temperature can be extracted for further analysis.

[0068] The battery tolerance range and the battery limit temperature when the battery system is in the temperature environment of all external temperature ranges are obtained respectively.

[0069] The cooling analysis module is used to obtain current data in the circuit connected to the cooling system when the battery module is at different external temperatures and the battery module is in the battery tolerance range and the battery limit temperature, and to set the tolerance current range and the limit current of the cooling system based on the current data.

[0070] The cooling analysis module is configured with a cooling analysis strategy, which includes: recording the maximum instantaneous current allowed to pass through the circuit connected to the battery system as the instantaneous MAX; recording the shortest time that the circuit can continue to operate when the instantaneous current in the circuit connected to the battery system is the instantaneous MAX as the cooling buffer time.

[0071] For any external temperature segment J1 from external temperature segment 1 to external temperature segment J, obtain the interval corresponding to the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of external temperature segment J1 and the temperature of the battery module is in the battery tolerance range, and record it as the tolerance current range; for example, in a data processing, the battery tolerance range obtained is 50℃ to 60℃, and within the battery tolerance range, the maximum value of the instantaneous current in the circuit connected to the cooling system is 40A, and the minimum value is 35A, then 35A to 40A is recorded as the tolerance current range.

[0072] The cooling analysis strategy also includes: obtaining the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of the external temperature segment J1 and the temperature of the battery module is the battery limit temperature, which is recorded as the limit current.

[0073] When the limiting current is less than or equal to the instantaneous MAX, the external temperature segment J1 is recorded as the stable operating temperature segment of the battery system; when the limiting current is less than or equal to the instantaneous MAX, it means that the current in the circuit can safely ensure the normal operation of the cooling system. When the limiting current is greater than the instantaneous MAX, it means that the instantaneous current in the circuit may cause a short circuit in the circuit. The cooling termination temperature of the cooling system should be set to cut off the power supply in time to protect the safety of the circuit.

[0074] When the limit current is greater than the instantaneous MAX, the point in the tolerance current range that is equal to the instantaneous MAX is recorded as the cooling limit point, and the temperature in the battery tolerance range corresponding to the instantaneous current being the cooling limit point is recorded as the cooling termination temperature.

[0075] Obtain the tolerance current curves and limit currents corresponding to all external temperature segments; obtain the cooling termination temperatures corresponding to all external temperature segments that are not recorded as stable operating temperature segments.

[0076] The multi-layer protection setting module is used to set a first-layer power-off protection, a second-layer buffer protection and a third-layer cooling protection for the battery system under different external temperatures.

[0077] The multi-layer protection setting module is configured with a three-layer protection strategy, which includes: setting a layer of power-off protection.

[0078] The first-layer power-off protection is: obtaining the external temperature when the battery system is running, and obtaining the external temperature segment in which the external temperature when the battery system is running is located, which is recorded as the real-time temperature segment.

[0079] When the real-time temperature segment contains the cooling termination temperature, the temperature of the battery module is obtained in real time during the operation of the battery system. When the temperature of the battery module is lower than the cooling termination temperature, the cooling system is used to cool the battery module. When the temperature of the battery module is greater than or equal to the cooling termination temperature, the cooling system and the battery module are powered off. When the real-time temperature segment contains the corresponding cooling termination temperature, it means that in the cooling analysis strategy, when the external temperature segment is the real-time temperature segment, the limiting current in the circuit connected to the cooling system during the operation of the battery system may be greater than the instantaneous MAX. Therefore, the temperature of the battery module should be judged so that the battery module can be powered off in time to prevent circuit short circuits and the like.

[0080] A second-layer buffer protection is set; the second-layer buffer protection is: when the real-time temperature segment does not contain the cooling termination temperature, the cooling system is continuously used to cool the battery module during the operation of the battery system, and the instantaneous current in the circuit connected to the cooling system is obtained in real time, which is recorded as the real-time instantaneous current; when the real-time instantaneous current is greater than the instantaneous MAX, the battery module is powered off, and then the cooling system is powered off after the cooling buffer time. The cooling buffer time can be set according to the time that the actual circuit can continue to operate safely when the instantaneous current in the circuit is greater than the instantaneous MAX. In this embodiment, the cooling buffer time is set to 1 minute.

[0081] Set up three-layer cooling protection; the three-layer cooling protection is: when the real-time temperature segment does not contain the cooling termination temperature and the real-time instantaneous current is always less than or equal to the instantaneous MAX during the operation of the battery system, use the cooling system to continuously cool down the battery module.

[0082] Example 2, please refer to Figure 2 As shown, in a second aspect, the present invention provides a multi-level battery system safety protection method, the battery system includes a battery management system, a battery module and a cooling system, including the following steps:

[0083] Step S1, placing the battery system in operation at different external temperatures, and using a battery management system to monitor the temperature and charging rate of the battery module during operation, and using a temperature analysis method to obtain the battery tolerance range and battery limit temperature at different external temperatures.

[0084] Step S1 includes: Step S101, obtaining the highest temperature and the lowest temperature of the external environment when the battery system is operating normally, which are recorded as the external upper limit temperature and the external lower limit temperature.

[0085] Step S102, divide the temperature between the lower limit temperature and the upper limit temperature into J segments on average, and record them as external temperature segment 1 to external temperature segment J in order from low to high, wherein the lowest temperature in external temperature segment 1 is the lower limit temperature of the outside world, and the highest temperature in external temperature segment J is the upper limit temperature of the outside world.

[0086] Step S103, placing the battery system in an environment with a temperature in the external temperature range 1 to the external temperature range J, and using the temperature analysis method to analyze the battery system in different temperature environments in turn and record various data in the battery system.

[0087] The temperature analysis method includes: step S1031, for a temperature environment in any temperature segment J1 from the temperature segment 1 to the temperature segment J, the battery system is charged until the battery module is fully charged and the battery management system is used to obtain the temperature of the battery module in real time.

[0088] Step S1032 , establishing a plane rectangular coordinate system, recorded as a battery temperature coordinate system, wherein the unit of the X-axis of the battery temperature coordinate system is time, and the unit of the Y-axis of the battery temperature coordinate system is temperature.

[0089] In the battery temperature coordinate system, the temperature of the battery module obtained by the battery management system is marked in the form of a curve, and the marked curve is recorded as a temperature change curve, wherein the X-axis coordinate corresponding to the leftmost point of the temperature change curve is the coordinate origin.

[0090] Step S1033, use the battery management system to obtain in real time the charging rate of the battery module after charging starts, record the time when the charging rate continues to rise after charging starts as the charging start time, record the time when the charging rate starts to decrease as the charging reduction time, obtain the percentage of power in the battery module during the charging reduction time, record it as the rate reduction percentage, obtain the percentage of power in the battery module when the charging protection of the battery module is triggered under normal charging conditions, record it as the standard reduction percentage.

[0091] Step S1034, when the rate reduction percentage is greater than or equal to the standard reduction percentage, the point with the largest ordinate in the temperature change curve is recorded as the extreme temperature point, the ordinate corresponding to the extreme temperature point is marked as the battery extreme temperature, and the interval formed by the lowest point of the ordinate and the highest point of the ordinate in the area other than the extreme temperature point in the temperature change curve is recorded as the battery tolerance interval.

[0092] Step S1035, when the rate reduction percentage is less than the standard reduction percentage, the point on the temperature change curve whose horizontal axis corresponds to the charging reduction time is recorded as the tolerance starting point, the point whose percentage of the power in the battery module is the standard reduction percentage is recorded as the tolerance end point, the curve between the tolerance starting point and the tolerance end point is recorded as the tolerance curve, the curve formed by the lowest point of the vertical axis and the highest point of the vertical axis in the tolerance curve is recorded as the battery tolerance range, the point with the largest vertical axis in the tolerance curve is recorded as the extreme temperature point, and the vertical axis corresponding to the extreme temperature point is marked as the battery extreme temperature.

[0093] Step S1036, respectively obtaining the battery tolerance range and the battery limit temperature when the battery system is in the temperature environment of all external temperature ranges.

[0094] Step S2, when the battery module is at different external temperatures and the battery module is in the battery tolerance range and the battery limit temperature, obtain the current data in the circuit connected to the cooling system, and set the tolerance current range and the limit current of the cooling system based on the current data.

[0095] Step S2 includes: step S201, recording the maximum instantaneous current allowed to pass through the circuit connected to the battery system as instantaneous MAX; recording the shortest time that the circuit can continue to operate when the instantaneous current in the circuit connected to the battery system is instantaneous MAX as cooling buffer time.

[0096] Step S202, for any external temperature segment J1 from external temperature segment 1 to external temperature segment J, obtain the interval corresponding to the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of the external temperature segment J1 and the temperature of the battery module is in the battery tolerance range, and record it as the tolerance current interval.

[0097] Step S203, obtaining the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of the external temperature segment J1 and the temperature of the battery module is the battery limit temperature, and recording it as the limit current.

[0098] Step S204: when the limiting current is less than or equal to the instantaneous MAX, the external temperature segment J1 is recorded as the stable operating temperature segment of the battery system.

[0099] Step S205, when the limit current is greater than the instantaneous MAX, the point in the tolerance current interval that is equal to the instantaneous MAX is recorded as the cooling limit point, and the temperature in the battery tolerance interval corresponding to the instantaneous current being the cooling limit point is recorded as the cooling termination temperature.

[0100] Step S206, obtaining the tolerance current curves and limit currents corresponding to all external temperature segments; obtaining the cooling termination temperatures corresponding to all external temperature segments that are not recorded as stable operating temperature segments.

[0101] Step S3, setting a first layer of power-off protection, a second layer of buffer protection and a third layer of cooling protection for the battery system at different external temperatures.

[0102] Step S3 includes: Step S301, setting a layer of power-off protection.

[0103] The first-layer power-off protection is: obtaining the external temperature when the battery system is running, and obtaining the external temperature segment in which the external temperature when the battery system is running is located, which is recorded as the real-time temperature segment.

[0104] When the real-time temperature segment contains the cooling termination temperature, the temperature of the battery module is obtained in real time during the operation of the battery system. When the temperature of the battery module is lower than the cooling termination temperature, the cooling system is used to cool the battery module; when the temperature of the battery module is greater than or equal to the cooling termination temperature, the cooling system and the battery module are powered off.

[0105] Step S302, setting a second-layer buffer protection; the second-layer buffer protection is: when the real-time temperature segment does not contain the cooling termination temperature, the cooling system is continuously used to cool the battery module during the operation of the battery system, and the instantaneous current in the circuit connected to the cooling system is obtained in real time, which is recorded as the real-time instantaneous current; when the real-time instantaneous current is greater than the instantaneous MAX, the battery module is powered off, and then the cooling system is powered off after the cooling buffer time.

[0106] Step S303, setting three-layer cooling protection; the three-layer cooling protection is: when the real-time temperature segment does not contain the cooling termination temperature and the real-time instantaneous current is always less than or equal to the instantaneous MAX during the operation of the battery system, the cooling system is used to continuously cool the battery module.

[0107] Working principle: First, the battery system is placed in different external temperatures for operation, and the battery management system is used to monitor the temperature and charging rate of the battery module during operation. The temperature analysis method is used to obtain the battery tolerance range and battery limit temperature at different external temperatures. Then, when the battery module is at different external temperatures and the battery module is in the battery tolerance range and battery limit temperature, the current data in the circuit connected to the cooling system is obtained, and the tolerance current range and limit current of the cooling system are set based on the current data. Finally, a first-layer power-off protection, a second-layer buffer protection and a third-layer cooling protection are set for the battery system at different external temperatures.

[0108] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0109] It should be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program codes. Among them, the storage medium may be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (Static Random Access Memory, referred to as SRAM), electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), erasable programmable read-only memory (Erasable Programmable Read Only Memory, referred to as EPROM), programmable read-only memory (Programmable Red-Only Memory, referred to as PROM), read-only memory (Read-Only Memory, referred to as ROM), magnetic memory, flash memory, magnetic disk or optical disk. These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0110] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

Claims

1. A multi-level battery system safety protection method, wherein the battery system includes a battery management system, a battery module and a cooling system, characterized in that: The steps include: The battery system is placed in different external temperatures for operation, and the battery management system is used to monitor the temperature and charging rate of the battery module during operation. The temperature analysis method is used to obtain the battery tolerance range and battery limit temperature under different external temperatures; When the battery module is at different external temperatures and the battery module is at a battery tolerance range and a battery limit temperature, current data in a circuit connected to the cooling system is obtained, and a tolerance current range and a limit current of the cooling system are set based on the current data; The battery system is set at different external temperatures with a first-layer power-off protection, a second-layer buffer protection, and a third-layer cooling protection; The battery system is placed in different external temperatures for operation, and the battery management system is used to monitor the temperature and charging rate of the battery module during operation. The temperature analysis method is used to obtain the battery tolerance range and battery limit temperature under different external temperatures, including: Obtain the maximum temperature and the minimum temperature of the external environment when the battery system is operating normally, and record them as the external upper limit temperature and the external lower limit temperature; The temperature between the lower limit temperature and the upper limit temperature is evenly divided into J segments, and recorded as the outer temperature segment 1 to the outer temperature segment J in order from low to high, wherein the lowest temperature in the outer temperature segment 1 is the lower limit temperature of the outer temperature, and the highest temperature in the outer temperature segment J is the upper limit temperature of the outer temperature; The battery systems are placed in environments with temperatures ranging from ambient temperature segment 1 to ambient temperature segment J, and the battery systems in different temperature environments are analyzed in turn using a temperature analysis method and various data in the battery systems are recorded; Temperature analysis methods include: For a temperature environment in any one of the external temperature segments J1 from the external temperature segment 1 to the external temperature segment J, the battery system is charged until the battery module is fully charged and the battery management system is used to obtain the temperature of the battery module in real time; Establish a plane rectangular coordinate system, recorded as a battery temperature coordinate system, wherein the unit of the X-axis of the battery temperature coordinate system is time, and the unit of the Y-axis of the battery temperature coordinate system is temperature; The temperature of the battery module obtained by the battery management system is marked in the form of a curve in the battery temperature coordinate system, and the marked curve is recorded as a temperature change curve, wherein the X-axis coordinate corresponding to the leftmost point of the temperature change curve is the coordinate origin; Use the battery management system to obtain the charging rate of the battery module in real time after charging starts, record the time when the charging rate continues to rise after charging starts as the charging start time, record the time when the charging rate starts to decrease as the charging reduction time, obtain the percentage of power in the battery module during the charging reduction time, record it as the rate reduction percentage, obtain the percentage of power in the battery module when the charging protection is triggered under normal charging conditions, record it as the standard reduction percentage; Temperature analysis also includes: When the rate reduction percentage is greater than or equal to the standard reduction percentage, the point with the largest ordinate in the temperature change curve is recorded as the limit temperature point, the ordinate corresponding to the limit temperature point is marked as the battery limit temperature, and the interval formed by the lowest point of the ordinate and the highest point of the ordinate in the area other than the limit temperature point in the temperature change curve is recorded as the battery tolerance interval; When the rate reduction percentage is less than the standard reduction percentage, the point corresponding to the charging reduction time on the temperature change curve is recorded as the tolerance starting point, the point where the percentage of the battery module power is the standard reduction percentage is recorded as the tolerance end point, the curve between the tolerance starting point and the tolerance end point is recorded as the tolerance curve, the curve formed by the lowest point of the ordinate and the highest point of the ordinate in the tolerance curve is recorded as the battery tolerance range, the point with the largest ordinate in the tolerance curve is recorded as the limit temperature point, and the ordinate corresponding to the limit temperature point is marked as the battery limit temperature; Obtain the battery tolerance range and battery limit temperature when the battery system is in a temperature environment of all external temperature ranges respectively; When the battery module is at different external temperatures and the battery module is at a battery tolerance range and a battery limit temperature, obtaining current data in a circuit connected to the cooling system, and setting a tolerance current range and a limit current of the cooling system based on the current data includes: The maximum instantaneous current allowed to pass through the circuit connected to the battery system is recorded as the instantaneous MAX; the shortest time that the circuit can continue to operate when the instantaneous current in the circuit connected to the battery system is the instantaneous MAX is recorded as the cooling buffer time; For any external temperature segment J1 from the external temperature segment 1 to the external temperature segment J, obtain the interval corresponding to the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of the external temperature segment J1 and the temperature of the battery module is in the battery tolerance range, and record it as the tolerance current interval; When the battery module is at different external temperatures and the battery module is at a battery tolerance range and a battery limit temperature, obtaining current data in a circuit connected to the cooling system, and setting a tolerance current range and a limit current of the cooling system based on the current data also includes: Obtain the instantaneous current in the circuit connected to the cooling system when the battery system is in the temperature environment of the external temperature segment J1 and the temperature of the battery module is the battery limit temperature, and record it as the limit current; When the limiting current is less than or equal to the instantaneous MAX, the external temperature segment J1 is recorded as the stable operating temperature segment of the battery system; When the limit current is greater than the instantaneous MAX, the point in the tolerance current interval that is equal to the instantaneous MAX is recorded as the cooling limit point, and the temperature in the battery tolerance interval corresponding to the instantaneous current being the cooling limit point is recorded as the cooling termination temperature; Obtain the tolerance current curves and limit currents corresponding to all external temperature segments; obtain the cooling termination temperatures corresponding to all external temperature segments that are not recorded as stable operating temperature segments.

2. The safety protection method for a multi-level battery system according to claim 1, characterized in that: The first-layer power-off protection, second-layer buffer protection, and third-layer cooling protection of the battery system set at different external temperatures include: Set up a layer of power-off protection; The first-layer power-off protection is as follows: obtaining the external temperature when the battery system is running, and obtaining the external temperature segment in which the external temperature when the battery system is running is located, which is recorded as the real-time temperature segment; When the real-time temperature segment contains the cooling termination temperature, the temperature of the battery module is obtained in real time during the operation of the battery system. When the temperature of the battery module is lower than the cooling termination temperature, the cooling system is used to cool the battery module; when the temperature of the battery module is greater than or equal to the cooling termination temperature, the cooling system and the battery module are powered off.

3. The safety protection method for a multi-level battery system according to claim 2, characterized in that: The first-layer power-off protection, second-layer buffer protection and third-layer cooling protection of the battery system set at different external temperatures also include: Set up a second layer of buffer protection; The second-level buffer protection is: when the real-time temperature segment does not contain the cooling termination temperature, the cooling system is continuously used to cool the battery module during the operation of the battery system, and the instantaneous current in the circuit connected to the cooling system is obtained in real time, which is recorded as the real-time instantaneous current; when the real-time instantaneous current is greater than the instantaneous MAX, the battery module is powered off, and then the cooling system is powered off after the cooling buffer time.

4. The safety protection method for a multi-level battery system according to claim 3, characterized in that: The first-layer power-off protection, second-layer buffer protection and third-layer cooling protection of the battery system set at different external temperatures also include: Set up three layers of cooling protection; The three-level cooling protection is: when the real-time temperature segment does not contain the cooling termination temperature and the real-time instantaneous current is always less than or equal to the instantaneous MAX during the operation of the battery system, the cooling system is used to continuously cool the battery module.

5. A safety protection system for a multi-level battery system, implemented based on the safety protection method for a multi-level battery system according to any one of claims 1 to 4, characterized in that: It includes temperature analysis module, cooling analysis module and multi-layer protection setting module; The temperature analysis module is used to operate the battery system at different external temperatures, and use the battery management system to monitor the temperature and charging rate of the battery module during operation, and use the temperature analysis method to obtain the battery tolerance range and battery limit temperature at different external temperatures; The cooling analysis module is used to obtain current data in the circuit connected to the cooling system when the battery module is at different external temperatures and the battery module is at the battery tolerance range and the battery limit temperature, and to set the tolerance current range and the limit current of the cooling system based on the current data; The multi-layer protection setting module is used to set a first-layer power-off protection, a second-layer buffer protection and a third-layer cooling protection for the battery system under different external temperatures.

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