Battery temperature calculation method and system

Abstract

The invention discloses a battery temperature calculation method and system, and belongs to the field of battery temperature management. Calculating real-time heating power by combining the real-time terminal voltage, the real-time current and the real-time open-circuit voltage of the battery; calibrating a first evolution coefficient of the heat exchange coefficient under different aging degrees and a second evolution coefficient of the heat exchange coefficient under different environment temperatures; calculating the surface heat exchange power by combining the real-time environment temperature, the heat exchange coefficient, the first evolution coefficient, the second evolution coefficient and the surface area of the outer surface of the battery; and calculating the battery temperature by combining the real-time heating power and the surface heat exchange power. According to the method, the performance parameters of the battery under different aging degrees are pre-calibrated to calculate the accurate real-time heating power, and the evolution coefficients of the heat exchange coefficient of the outer surface of the battery under different aging degrees and different environment temperatures are pre-calibrated to calculate the accurate surface heating power; and the accurate battery temperature is obtained by combining the real-time heating power and the surface heat exchange power.

Description

Technical Field

[0001] The present application relates to the field of battery temperature management, and specifically to a battery temperature calculation method and system. Background Art

[0002] With the increasing promotion of electric vehicles and energy storage systems, the research on battery packs has gradually deepened. As the core part of the battery pack, the accuracy of battery state estimation is self-evidently important to the battery management system. In addition to being affected by the algorithm used, the accuracy of battery state estimation is also affected by the accuracy of temperature. When designing a battery pack, in order to save costs, the temperature of each battery is not collected, but sparse sampling is performed in each battery pack. The battery pack includes multiple batteries, which are simply mapped to the temperature of each battery. However, the position of each battery is different, and there are certain differences in heat exchange, etc. Sparse temperature sampling cannot guarantee the accuracy of the temperature of each battery.

[0003] Patent CN 115659790 A proposes a real-time temperature detection method for a power battery pack to achieve temperature detection and thermal field analysis of the power battery pack. The temperature field is simulated using the current and voltage information and material thermodynamic parameters of the power battery pack, and the discrete measured temperature data is corrected through a deep neural network and a Kalman filter, so that the established temperature field model can more realistically reflect the actual temperature field distribution of the battery pack. However, this method has high requirements for chips when used on a whole vehicle, which increases the computing load and cost. Summary of the invention

[0004] The present application provides a battery temperature calculation method and system, which can solve the technical problem in the prior art that the battery temperature cannot be accurately obtained.

[0005] In a first aspect, an embodiment of the present application provides a battery temperature calculation method, the method comprising:

[0006] Calibrate the performance parameters of the battery at different aging degrees, wherein the performance parameters include the open circuit voltage of the battery at different remaining capacities;

[0007] The real-time heating power is calculated by combining the real-time terminal voltage, real-time current, real-time aging degree and open circuit voltage corresponding to the real-time remaining power of the battery at the current sampling moment;

[0008] Obtaining a heat transfer coefficient of an outer surface of a battery, and calibrating a first evolution coefficient of the heat transfer coefficient at different aging degrees and a second evolution coefficient at different ambient temperatures;

[0009] The surface heat transfer power is calculated by combining the real-time ambient temperature, the heat transfer coefficient, the first evolution coefficient, the second evolution coefficient, and the surface area of ​​the battery outer surface;

[0010] The battery temperature is calculated by combining the real-time heating power and the surface heat exchange power.

[0011] In combination with the first aspect, in one implementation, the real-time heating power is calculated using the following formula:

[0012]

[0013] in,

[0014] k represents the current sampling time;

[0015] k-1 represents the previous sampling time;

[0016] Cap total Indicates the real-time aging degree at the current sampling time calculated based on the battery's cumulative throughput table;

[0017] p k,selfheating Indicates the real-time heating power at the current sampling moment;

[0018] I k Indicates the real-time current at the current sampling moment;

[0019] OCV k (Cap total ) indicates that the real-time aging degree is Cap total The open circuit voltage corresponding to the real-time remaining power;

[0020] U k Indicates the real-time terminal voltage at the current sampling moment;

[0021] T k-1 Indicates the battery temperature at the previous sampling moment.

[0022] In combination with the first aspect, in one implementation, the method further includes:

[0023] Use the second-order RC model to simulate the battery and calibrate the performance parameters of the battery at different aging levels;

[0024] The performance parameters also include ohmic internal resistance, electrochemical polarization resistance, electrochemical polarization capacitance, concentration polarization resistance, and concentration polarization capacitance at different residual capacities.

[0025] In combination with the first aspect, in one implementation, the real-time terminal voltage is calculated by combining the real-time aging degree and the performance parameters corresponding to the real-time remaining power, the real-time current, and the sampling time interval.

[0026] In combination with the first aspect, in one implementation, the real-time terminal voltage is calculated using the following formula:

[0027]

[0028] in,

[0029] k represents the current sampling time;

[0030] k-1 represents the previous sampling time;

[0031] Cap total Indicates the real-time aging degree at the current sampling time calculated based on the battery's cumulative throughput table;

[0032] U k Indicates the real-time terminal voltage at the current sampling moment;

[0033] OCV k (Cap total ) indicates that the real-time aging degree is Cap total The open circuit voltage corresponding to the real-time remaining power;

[0034] I k Indicates the real-time current of the battery at the current sampling moment;

[0035] R0(Cap total ) indicates that the real-time aging degree is Cap total The ohmic internal resistance corresponding to the real-time remaining power;

[0036] U 1,k-1 Indicates the concentration polarization voltage obtained by converting the concentration polarization resistance and concentration polarization capacitance at the previous sampling moment;

[0037] e represents a natural constant;

[0038] Δt represents the sampling time interval between adjacent sampling moments;

[0039] R1(Cap total ) indicates that the real-time aging degree is Cap total The concentration polarization resistance corresponding to the real-time remaining power;

[0040] C1(Cap total ) indicates that the real-time aging degree is Cap total The concentration polarization capacitance corresponding to the real-time remaining power;

[0041] R2(Cap total ) indicates that the real-time aging degree is Cap total The electrochemical polarization resistance corresponding to the real-time remaining power;

[0042] C2(Cap total ) indicates that the real-time aging degree is Cap totalThe electrochemical polarization capacitance corresponding to the real-time remaining power.

[0043] In combination with the first aspect, in one implementation, the method further includes:

[0044] The first evolution coefficient is obtained by collecting heat transfer coefficients at different aging degrees and calculating their ratios;

[0045] The second evolution coefficient is obtained by collecting heat transfer coefficients at different ambient temperatures and calculating their ratio.

[0046] In combination with the first aspect, in one embodiment, the battery outer surface includes a battery side surface, a battery top surface, and a battery top surface;

[0047] After calculating the surface heat transfer power of each outer surface of the battery by combining the real-time ambient temperature, heat transfer coefficient, the first evolution coefficient corresponding to the real-time aging degree, the second evolution coefficient corresponding to the real-time ambient temperature, and the surface area, the battery temperature is calculated by combining the real-time heating power and the surface heat transfer power of all outer surfaces of the battery.

[0048] In combination with the first aspect, in one implementation, the surface heat exchange power is calculated using the following formula:

[0049] p Sur =(T ambient -T k-1 )*h SurFace *k1(Time)*k2(T envi )*A SurFace

[0050] in,

[0051] p Sur Indicates the surface heat transfer power of the battery outer surface;

[0052] T ambient Indicates the real-time ambient temperature;

[0053] T k-1 Indicates the battery temperature at the previous sampling moment;

[0054] h SurFace Indicates the heat transfer coefficient of the battery outer surface;

[0055] k1(Time) represents the first evolution coefficient of the heat transfer coefficient at the corresponding aging degree;

[0056] k2(T envi ) represents the second evolution coefficient of the heat transfer coefficient at the corresponding ambient temperature;

[0057] A SurFace Represents the surface area of ​​the battery's exterior surface.

[0058] In combination with the first aspect, in one implementation, the battery temperature is calculated using the following formula:

[0059]

[0060] in,

[0061] T k Indicates the battery temperature at the current sampling moment;

[0062] T k-1 Indicates the battery temperature at the previous sampling moment;

[0063] p Sur Indicates the surface heat transfer power of the battery outer surface;

[0064] δt represents the calculation period;

[0065] C cell represents the specific heat capacity of the battery;

[0066] M cell Indicates the quality of the battery.

[0067] In a second aspect, an embodiment of the present application provides a battery temperature calculation system, the battery temperature calculation system comprising:

[0068] A data calibration module, which is used to calibrate the performance parameters of the battery at different aging degrees, the performance parameters including the open circuit voltage of the battery at different remaining capacities; and is also used to obtain the heat transfer coefficient of the outer surface of the battery, and calibrate the first evolution coefficient of the heat transfer coefficient at different aging degrees, and the second evolution coefficient at different ambient temperatures;

[0069] The data processing module is used to calculate the real-time heating power by combining the real-time terminal voltage, real-time current, real-time aging degree and open circuit voltage corresponding to the real-time remaining power of the battery at the current sampling moment; calculate the surface heat exchange power by combining the real-time ambient temperature, heat transfer coefficient, first evolution coefficient, second evolution coefficient and the surface area of ​​the outer surface of the battery; calculate the battery temperature by combining the real-time heating power and the surface heat exchange power.

[0070] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0071] By pre-calibrating the performance parameters of the battery at different aging degrees, the real-time terminal voltage, real-time current, real-time aging degree, and real-time remaining power of the battery at the current sampling moment are obtained, and the performance parameter table is searched according to the real-time aging degree and the real-time remaining power to obtain the corresponding open circuit voltage. The accurate real-time heating power is calculated in combination with the real-time terminal voltage, real-time current, and open circuit voltage of the battery at the current sampling moment. By pre-calibrating the evolution coefficient of the heat transfer coefficient of the outer surface of the battery at different aging degrees and different ambient temperatures, the accurate surface heat transfer power is calculated in combination with the real-time ambient temperature, the heat transfer coefficient, the first evolution coefficient, the second evolution coefficient, and the surface area of ​​the outer surface of the battery. The accurate battery temperature is obtained by combining the real-time heating power and the surface heat exchange power. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a flow chart of an embodiment of a method for calculating battery temperature of the present application;

[0073] Figure 2 This is a functional module diagram of an embodiment of a battery temperature calculation system of the present application. DETAILED DESCRIPTION

[0074] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0075] First, some technical terms in the present application are explained to facilitate those skilled in the art to understand the present application.

[0076] Remaining capacity: (State of Charge, referred to as SOC), is the ratio of the remaining capacity of the battery after it has been used for a period of time or has been left unused for a long time to its fully charged capacity, usually expressed as a percentage. Its value range is 0 to 1. When SOC = 0, it means that the battery is fully discharged, and when SOC = 1, it means that the battery is fully charged.

[0077] Terminal voltage: (Terminal potential, abbreviated as TP) is the voltage between the positive and negative poles of the power supply, also known as the circuit terminal voltage or terminal voltage.

[0078] Open circuit voltage: (OCV for short), the terminal voltage of a battery in an open circuit state is called open circuit voltage. The open circuit voltage of a battery is equal to the difference between the electrode potential of the positive electrode and the electrode potential of the negative electrode of the battery when the battery is disconnected (that is, when no current passes through the two electrodes).

[0079] Hybrid Pulse Power Characterization Test: (HPPC) test is a characteristic test used to reflect the pulse charge and discharge performance of power batteries. Its purpose is to demonstrate the discharge pulse and regenerative charging pulse power capabilities of power-assisted targets at different discharge depths.

[0080] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0081] In a first aspect, an embodiment of the present application provides a battery temperature calculation method.

[0082] In one embodiment, referring to Figure 1 , Figure 1 This is a flow chart of an embodiment of a battery temperature calculation method of the present application. Figure 1 As shown, the battery temperature calculation method includes:

[0083] Step S1, calibrate the performance parameters of the battery at different aging degrees, the performance parameters include the open circuit voltage of the battery at different remaining capacities. Obtain the heat transfer coefficient of the outer surface of the battery, and calibrate the first evolution coefficient of the heat transfer coefficient at different aging degrees and the second evolution coefficient at different ambient temperatures.

[0084] Step S2: Calculate the real-time heating power by combining the real-time terminal voltage, real-time current, real-time aging degree and open circuit voltage corresponding to the real-time remaining power of the battery at the current sampling moment. Calculate the surface heat transfer power by combining the real-time ambient temperature, heat transfer coefficient, first evolution coefficient, second evolution coefficient and the surface area of ​​the battery outer surface.

[0085] Step S3: Calculate the battery temperature by combining the real-time heating power and the surface heat exchange power.

[0086] In this embodiment, in view of the common equivalent circuit models including first-order, second-order, third-order and even n-order RC networks. The error of the first-order RC network model is relatively large, and the accuracy of the second-order and third-order RC network models will be significantly improved. In addition, the higher the order of the RC network, the better. When the order exceeds the fifth order, the model error will increase, and the calculation complexity will increase further. Considering the model accuracy and calculation complexity, the second-order RC network equivalent circuit model is generally selected, that is, the secondary RC model is used to simulate the working principle of the battery.

[0087] After selecting the equivalent circuit model, the performance parameters such as the open circuit voltage of the battery at different aging degrees are first calibrated through experimental methods. It should be noted that at the same aging degree, performance parameters such as the open circuit voltage are also related to the SOC of the battery.

[0088] When conducting the performance parameter collection experiment, after adjusting the SOC of the battery to the target value, it is left for 3 hours to obtain the OCV, and then the battery is subjected to the HPPC test. When conducting the HPPC test, the battery can be pulse discharged for 30S, and then the ohmic internal resistance R0 is calculated and the RC parameters are fitted according to the time-voltage curve corresponding to the discharge pulse to obtain two sets of RC data (i.e., concentration polarization resistance R1, electrochemical polarization resistance R2, concentration polarization capacitance C1, electrochemical polarization capacitance C2, OCV). The pulse is not limited to 30s and is not limited to discharge.

[0089] HPPC test is used to calibrate the performance parameters of batteries at different aging levels to obtain multiple performance parameter tables. The aging level can be expressed as the cumulative throughput Cap after the battery leaves the factory. total Characterization can also be characterized by usage time, etc. As shown in Table 1 below, it is a table of various battery performance parameters obtained through experimental methods when the aging degree is 0, that is, when the battery has not aged:

[0090] Table 1 Battery performance parameters when the aging degree is 0

[0091]

[0092] After calibrating the performance parameters of the battery at different aging degrees, obtain the real-time terminal voltage, real-time current, real-time aging degree, and real-time SOC of the battery at the current sampling moment, search the performance parameter table according to the real-time aging degree and real-time SOC, obtain the corresponding open-circuit voltage, and calculate the real-time heating power of the battery in combination with the real-time terminal voltage, real-time current, and open-circuit voltage at the current sampling moment.

[0093] In addition to calibrating the performance parameters of the battery at different aging degrees, it is also necessary to calibrate the first evolution coefficient of the heat transfer coefficient of the outer surface of the battery at different aging degrees, and the second evolution coefficient at different ambient temperatures. Specifically, after aging, the battery material will deform, squeeze, etc., resulting in changes in the heat transfer coefficient. At different ambient temperatures, the degree of thermal expansion and contraction of the material is different, and the contact between batteries or between batteries and cooling plates is also different, and the heat transfer coefficient will also change. By placing the battery in a high temperature environment, the aging of the battery material is accelerated, and the speed of high temperature aging is equivalent to the speed of normal aging, the calibration time is reduced to obtain the evolution coefficient of the heat transfer coefficient at different aging degrees and different ambient temperatures.

[0094] The surface heat transfer power is calculated by combining the real-time ambient temperature, the heat transfer coefficient, the first evolution coefficient, the second evolution coefficient, and the surface area of ​​the battery outer surface.

[0095] The real-time heating power represents the heat generated by the battery, and the surface heat exchange power represents the heat dissipated by the battery. The difference between the two is the heat inside the battery, from which the battery temperature can be calculated.

[0096] The present invention obtains the real-time terminal voltage, real-time current, real-time aging degree, and real-time SOC of the battery at the current sampling moment by pre-calibrating the performance parameters of the battery at different aging degrees, and searches the performance parameter table according to the real-time aging degree and the real-time SOC to obtain the corresponding open-circuit voltage, and calculates the accurate real-time heating power in combination with the real-time terminal voltage, real-time current, and open-circuit voltage of the battery at the current sampling moment. The present invention pre-calibrates the evolution coefficient of the heat transfer coefficient of the battery outer surface at different aging degrees and different ambient temperatures, and calculates the accurate surface heat transfer power in combination with the real-time ambient temperature, the heat transfer coefficient, the first evolution coefficient, the second evolution coefficient, and the surface area of ​​the battery outer surface, and obtains the accurate battery temperature in combination with the real-time heating power and the surface heat transfer power.

[0097] Since the influence of battery aging is taken into account, the calculation accuracy of the heating power can be improved. The calculation of the heat exchange power also fully considers the aging of the battery, that is, the influence of the aging of the battery material on the heat exchange coefficient, so the calculation accuracy of the heat exchange power can be improved. Because the rise and fall of the battery temperature is jointly determined by the heating power and the heat exchange power, improving the calculation accuracy of the two can obtain a more accurate battery temperature. Furthermore, in one embodiment, the above real-time heating power is calculated using the following formula (1):

[0098]

[0099] Where k represents the current sampling time. k-1 represents the previous sampling time. total Indicates the real-time aging degree at the current sampling time calculated based on the battery's cumulative throughput table. k,selfheating Indicates the real-time heating power at the current sampling moment. k Indicates the real-time current at the current sampling moment. OCV k (Cap total ) indicates that the real-time aging degree is Cap total The open circuit voltage corresponding to the real-time remaining power. k Indicates the real-time terminal voltage at the current sampling moment. T k-1 Indicates the battery temperature at the previous sampling moment.

[0100] In this embodiment, U kIt represents the real-time terminal voltage at the current sampling moment, which can be obtained through actual measurement or calculated in combination with performance parameters. By adding the content after the minus sign in formula (1), the influence of temperature on OCV is compensated, thereby improving the calculation accuracy of real-time heating power.

[0101] Furthermore, in one embodiment, the above method further includes:

[0102] The battery is simulated with a second-order RC model and the performance parameters of the battery at different aging degrees are calibrated.

[0103] The above performance parameters also include ohmic internal resistance, electrochemical polarization resistance, electrochemical polarization capacitance, concentration polarization resistance, and concentration polarization capacitance at different SOCs.

[0104] In this embodiment, considering the model accuracy and calculation complexity comprehensively, a second-order RC network equivalent circuit model is generally selected, that is, a secondary RC model is used to simulate the working principle of the battery.

[0105] Furthermore, in one embodiment, the real-time terminal voltage is calculated by combining the real-time aging degree and the performance parameter corresponding to the real-time SOC, the real-time current, and the sampling time interval.

[0106] Furthermore, in one embodiment, the above-mentioned real-time terminal voltage is calculated using the following formula (2):

[0107]

[0108] Where k represents the current sampling time. k-1 represents the previous sampling time. total Indicates the real-time aging degree at the current sampling time calculated based on the battery's cumulative throughput table. k Indicates the real-time terminal voltage at the current sampling moment. OCV k (Cap total ) indicates that the real-time aging degree is Cap total The open circuit voltage corresponding to the real-time remaining power. k Indicates the real-time current of the battery at the current sampling moment. R0(Cap total ) indicates that the real-time aging degree is Cap total The ohmic internal resistance corresponding to the real-time remaining power. 1,k-1 Represents the concentration polarization voltage converted from the concentration polarization resistance and concentration polarization capacitance at the previous sampling moment. e represents a natural constant. Δt represents the sampling time interval between adjacent sampling moments. R1(Cap total ) indicates that the real-time aging degree is Cap total The concentration polarization resistance corresponding to the real-time remaining capacity. total ) indicates that the real-time aging degree is Captotal The concentration polarization capacitor corresponding to the real-time remaining power. total ) indicates that the real-time aging degree is Cap total The electrochemical polarization resistance corresponding to the real-time remaining capacity. total ) indicates that the real-time aging degree is Cap total The electrochemical polarization capacitance corresponding to the real-time remaining power.

[0109] Formula (2) can be used to estimate the real-time terminal voltage, U k The currently sampled terminal voltage may also be used; however, the real-time terminal voltage may be estimated in advance using formula (2), so that the battery temperature may be calculated in advance, and the thermal management strategy may be optimized in advance.

[0110] Furthermore, in one embodiment, the above method further includes:

[0111] The first evolution coefficient is obtained by collecting heat transfer coefficients at different aging degrees and calculating their ratios.

[0112] The second evolution coefficient is obtained by collecting the heat transfer coefficients at different ambient temperatures and calculating their ratios.

[0113] In this embodiment, taking the calibration of the first evolution coefficient of the heat transfer coefficient between the bottom surface of the battery and the cooling plate as an example, the heat transfer coefficient without aging at room temperature (25°C) is first calibrated as h_25_new, and then the heat transfer coefficient after aging for one month is calibrated again as h_25_1m, then the variation coefficient is h_25_new / h_25_1m, and the calibration methods at other different aging degrees are similar. Taking the calibration of the second evolution coefficient of the heat transfer coefficient between the bottom surface of the battery and the cooling plate as an example, the heat transfer coefficient at room temperature (25°C) is first calibrated as h_25, and then the ambient temperature is increased to 45°C, and then the heat transfer coefficient is calibrated again as h_45, then the second evolution coefficient is: h_45 / h_25, and the calibration methods at other ambient temperatures are similar.

[0114] Furthermore, in one embodiment, the battery outer surface includes a battery side surface, a battery top surface, and a battery top surface.

[0115] After calculating the surface heat transfer power of each outer surface of the battery by combining the real-time ambient temperature, heat transfer coefficient, the first evolution coefficient corresponding to the real-time aging degree, the second evolution coefficient corresponding to the real-time ambient temperature, and the surface area, the battery temperature is calculated by combining the real-time heating power and the surface heat transfer power of all outer surfaces of the battery.

[0116] In this embodiment, for each outer surface of the battery, the same method is used to calculate the surface heat exchange power of the corresponding surface, and the sum of the heat exchange powers of all surfaces is calculated to obtain the heat dissipation of all outer surfaces of the battery.

[0117] Furthermore, in one embodiment, the surface heat exchange power is calculated using the following formula (3):

[0118] p Sur =(T ambient -T k-1 )*h SurFace *k1(Time)*k2(T envi )*A SurFace (3)

[0119] Among them, p Sur Indicates the surface heat transfer power of the battery outer surface. T ambient Indicates the real-time ambient temperature. T k-1 Indicates the battery temperature at the previous sampling moment. h SurFace Indicates the heat transfer coefficient of the battery outer surface. k1(Time) indicates the first evolution coefficient of the heat transfer coefficient at the corresponding aging degree. k2(T envi ) represents the second evolution coefficient of the heat transfer coefficient at the corresponding ambient temperature. SurFace Represents the surface area of ​​the battery's exterior surface.

[0120] In this embodiment, the heat transfer coefficients of the side, top and bottom surfaces of the battery are calibrated as follows: SideFace 、h TopFace , and h SubFace , the calculation formula for the surface heat transfer power of the battery side is shown in formula (4), the calculation formula for the surface heat transfer power of the top surface is shown in formula (5), and the calculation formula for the surface heat transfer power of the bottom surface is shown in formula (6).

[0121] p Side =

[0122] (T ambient -T k-1 )*h SideFace *k 1,SideFace (Time)*k 2,SideFace (T envi )*A SideFace (4)

[0123] p Top =(T ambient -T k-1 )*h TopFace *k 1,TopFace (Time)*k 2,TopFace (T envi )*A TopFace (5)

[0124] p Sub =(T ambient -T k-1 )*h SubFace*k 1,SubFace (Time)*k 2,SubFace (T envi )*A SubFace (6)

[0125] Among them, p Side Indicates the heat transfer power on the side of the battery. SideFace Represents the surface area of ​​the battery side. Top Indicates the surface heat transfer power of the battery top surface. TopFace Represents the surface area of ​​the top surface of the battery. Sub Indicates the surface heat transfer power of the battery bottom. SubFace Represents the surface area of ​​the bottom of the battery. k 1,SideFace (Time) represents the first evolution coefficient of the heat transfer coefficient on the battery side at different aging degrees. k 2,SideFace (T envi ) represents the second evolution coefficient of the heat transfer coefficient on the battery side at different ambient temperatures. k 1,TopFace (Time) represents the first evolution coefficient of the heat transfer coefficient of the battery top surface at different aging degrees. k 2,topFace (T envi ) represents the second evolution coefficient of the heat transfer coefficient on the top surface of the battery at different ambient temperatures. 1,1ubFace (Time) represents the first evolution coefficient of the heat transfer coefficient of the battery bottom surface at different aging degrees. k 2,SubFace (T envi ) represents the second evolution coefficient of the heat transfer coefficient of the battery bottom surface at different ambient temperatures.

[0126] Furthermore, in one embodiment, the battery temperature is calculated using the following formula (7):

[0127]

[0128] Among them, T k Indicates the battery temperature at the current sampling time. T k-1 Indicates the battery temperature at the previous sampling moment. Sur Represents the surface heat transfer power of the battery outer surface. δt represents the calculation period. C cell Represents the specific heat capacity of the battery. M cell Indicates the quality of the battery.

[0129] When the temperature rises or falls, the energy absorbed or released is: Q = cm*Δt, where Δt represents the change in temperature, c represents the specific heat capacity of the substance, and m represents the mass of the substance. Therefore, the change in temperature is Q can be calculated by multiplying the heat transfer power by the time (Q = p Sur *δt). Therefore, the temperature change of the battery during δt is Therefore, the temperature at time k is equal to the temperature at time k-1 plus the temperature change of the battery during δt.

[0130] Assuming that the number of batteries in the battery pack is n, the temperature of the batteries in the battery pack is calculated using the following formula (8):

[0131]

[0132] Among them, T k,i Indicates the battery temperature of the battery numbered i at the current sampling time k. T k-1,i represents the battery temperature of the battery numbered i at the previous sampling time k-1. i,selfheating Indicates the real-time heating power of the battery numbered i at the current sampling time k. i,Side Indicates the side heat transfer power of the battery numbered i at the current sampling time k. i,Top It represents the heat transfer power of the top surface of the battery numbered i at the current sampling time k. i,Sub It represents the bottom surface heat exchange power of the battery numbered i at the current sampling time k. n represents the total number of batteries in the battery pack.

[0133] In summary, the present invention proposes a method based on the second-order RC model to calculate the real-time heat generation power of the battery itself and calibrate the heat transfer coefficient of each battery in the battery pack and calculate the heat transfer power of each surface. The temperature of each battery is calculated in real time based on the steady-state temperature state, thereby improving the estimation accuracy of the real-time temperature of the battery, which is beneficial to improving the state estimation accuracy of each battery in the battery pack.

[0134] In a second aspect, an embodiment of the present application also provides a battery temperature calculation system.

[0135] In one embodiment, referring to Figure 2 , Figure 2 This is a functional module diagram of an embodiment of the battery temperature calculation system of the present application. Figure 2 As shown, the battery temperature calculation system includes:

[0136] The data calibration module is used to simulate the battery with a second-order RC model and calibrate the performance parameters of the battery at different aging levels, including the open circuit voltage of the battery at different remaining capacity (SOC). It is also used to obtain the heat transfer coefficient of the outer surface of the battery and calibrate the first evolution coefficient of the heat transfer coefficient at different aging levels and the second evolution coefficient at different ambient temperatures.

[0137] The data processing module is used to calculate the real-time heating power by combining the real-time terminal voltage, real-time current, real-time aging degree and open circuit voltage corresponding to the real-time SOC of the battery at the current sampling moment. The surface heat transfer power is calculated by combining the real-time ambient temperature, heat transfer coefficient, first evolution coefficient, second evolution coefficient and the surface area of ​​the battery outer surface. The battery temperature is calculated by combining the real-time heating power and the surface heat transfer power.

[0138] In this embodiment, the performance parameters of the battery at different aging degrees are pre-calibrated to calculate the accurate real-time heating power, and the evolution coefficient of the heat exchange coefficient of the battery outer surface at different aging degrees and different ambient temperatures is pre-calibrated to calculate the accurate surface heating power. The real-time heating power and the surface heat exchange power are combined to obtain the accurate battery temperature.

[0139] Among them, the functional implementation of each module in the above-mentioned battery temperature calculation system corresponds to each step in the above-mentioned battery temperature calculation method embodiment, and its functions and implementation processes are no longer repeated here.

[0140] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0141] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0142] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0143] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B. "And / or" in the text is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0144] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0145] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0146] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A battery temperature calculation method, characterized in that: The method comprises: Calibrate the performance parameters of the battery at different aging degrees, wherein the performance parameters include the open circuit voltage of the battery at different remaining capacities; The real-time heating power is calculated by combining the real-time terminal voltage, real-time current, real-time aging degree and open circuit voltage corresponding to the real-time remaining power of the battery at the current sampling moment; Obtaining a heat transfer coefficient of an outer surface of a battery, and calibrating a first evolution coefficient of the heat transfer coefficient at different aging degrees and a second evolution coefficient at different ambient temperatures; The surface heat transfer power is calculated by combining the real-time ambient temperature, the heat transfer coefficient, the first evolution coefficient, the second evolution coefficient, and the surface area of ​​the battery outer surface; The battery temperature is calculated by combining the real-time heating power and the surface heat exchange power.

2. The battery temperature calculation method according to claim 1, characterized in that: The real-time heating power is calculated using the following formula: in, k represents the current sampling time; k-1 represents the previous sampling time; Cap total Indicates the real-time aging degree at the current sampling time calculated based on the battery's cumulative throughput table; p k,selfheating Indicates the real-time heating power at the current sampling moment; I k Indicates the real-time current at the current sampling moment; OCV k (Cap total ) indicates that the real-time aging degree is Cap total The open circuit voltage corresponding to the real-time remaining power; U k Indicates the real-time terminal voltage at the current sampling moment; T k-1 Indicates the battery temperature at the previous sampling moment.

3. The battery temperature calculation method according to claim 1, characterized in that: The method further comprises: Use the second-order RC model to simulate the battery and calibrate the performance parameters of the battery at different aging levels; The performance parameters also include ohmic internal resistance, electrochemical polarization resistance, electrochemical polarization capacitance, concentration polarization resistance, and concentration polarization capacitance at different residual capacities.

4. The battery temperature calculation method according to claim 3, characterized in that: The real-time terminal voltage is calculated by combining the real-time aging degree and the performance parameters corresponding to the real-time remaining power, the real-time current, and the sampling time interval.

5. The battery temperature calculation method according to claim 4, characterized in that: The real-time terminal voltage is calculated using the following formula: in, k represents the current sampling time; k-1 represents the previous sampling time; Cap total Indicates the real-time aging degree at the current sampling time calculated based on the battery's cumulative throughput table; U k Indicates the real-time terminal voltage at the current sampling moment; OCV k (Cap total ) indicates that the real-time aging degree is Cap total The open circuit voltage corresponding to the real-time remaining power; I k Indicates the real-time current of the battery at the current sampling moment; R0(Cap total ) indicates that the real-time aging degree is Cap total The ohmic internal resistance corresponding to the real-time remaining power; U 1,k-1 Indicates the concentration polarization voltage obtained by converting the concentration polarization resistance and concentration polarization capacitance at the previous sampling moment; e represents a natural constant; Δt represents the sampling time interval between adjacent sampling moments; R1(Cap total ) indicates that the real-time aging degree is Cap total The concentration polarization resistance corresponding to the real-time remaining power; C1(Cap total ) indicates that the real-time aging degree is Cap total The concentration polarization capacitance corresponding to the real-time remaining power; R2(Cap total ) indicates that the real-time aging degree is Cap total The electrochemical polarization resistance corresponding to the real-time remaining power; C2(Cap total ) indicates that the real-time aging degree is Cap total The electrochemical polarization capacitance corresponding to the real-time remaining power.

6. The battery temperature calculation method according to claim 1, characterized in that: The method further comprises: The first evolution coefficient is obtained by collecting heat transfer coefficients at different aging degrees and calculating their ratios; The second evolution coefficient is obtained by collecting heat transfer coefficients at different ambient temperatures and calculating their ratio.

7. The battery temperature calculation method according to claim 1, characterized in that: The battery outer surface includes a battery side surface, a battery top surface, and a battery top surface; After calculating the surface heat transfer power of each outer surface of the battery by combining the real-time ambient temperature, heat transfer coefficient, the first evolution coefficient corresponding to the real-time aging degree, the second evolution coefficient corresponding to the real-time ambient temperature, and the surface area, the battery temperature is calculated by combining the real-time heating power and the surface heat transfer power of all outer surfaces of the battery.

8. The battery temperature calculation method according to claim 1, characterized in that: The surface heat transfer power is calculated using the following formula: p Sur =(T ambient -T k-1 )*h SurFace *k1(Time)*k2(T envi )*A SurFace in, p Sur Indicates the surface heat transfer power of the battery outer surface; T ambient Indicates the real-time ambient temperature; T k-1 Indicates the battery temperature at the previous sampling moment; h SurFace Indicates the heat transfer coefficient of the battery outer surface; k1(Time) represents the first evolution coefficient of the heat transfer coefficient at the corresponding aging degree; k2(T envi ) represents the second evolution coefficient of the heat transfer coefficient at the corresponding ambient temperature; A surFace Represents the surface area of ​​the battery's exterior surface.

9. The battery temperature calculation method according to claim 1, characterized in that: The battery temperature is calculated using the following formula: in, T k Indicates the battery temperature at the current sampling moment; T k-1 Indicates the battery temperature at the previous sampling moment; p Sur Indicates the surface heat transfer power of the battery outer surface; δt represents the calculation period; C cell represents the specific heat capacity of the battery; M cell Indicates the quality of the battery.

10. A battery temperature calculation system, characterized in that: The battery temperature calculation system comprises: A data calibration module, which is used to calibrate the performance parameters of the battery at different aging degrees, the performance parameters including the open circuit voltage of the battery at different remaining capacities; and is also used to obtain the heat transfer coefficient of the outer surface of the battery, and calibrate the first evolution coefficient of the heat transfer coefficient at different aging degrees, and the second evolution coefficient at different ambient temperatures; The data processing module is used to calculate the real-time heating power by combining the real-time terminal voltage, real-time current, real-time aging degree and open circuit voltage corresponding to the real-time remaining power of the battery at the current sampling moment; calculate the surface heat exchange power by combining the real-time ambient temperature, heat transfer coefficient, first evolution coefficient, second evolution coefficient and the surface area of ​​the outer surface of the battery; calculate the battery temperature by combining the real-time heating power and the surface heat exchange power.

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