A method, system, and vehicle for controlling the discharge power of a power battery.

Abstract

This invention discloses a method, system, and vehicle for controlling the discharge power of a power battery, comprising: obtaining the lowest single-cell temperature T of the current power battery. min Minimum unit voltage U min and SOC value; if T min If the operating temperature is not within the preset range, the discharge power of the power battery will be 0; if T min If the operating temperature range is within the preset range and undervoltage is triggered, then the undervoltage power limiting strategy is executed; if T min Within the preset operating temperature range, and without triggering undervoltage, the discharge power of the power battery is set to P. Here, P represents the power output based on the current lowest single-cell temperature T of the power battery. min The discharge power is obtained by querying a preset discharge power table based on the SOC value. This preset discharge power table is a table obtained through calibration that corresponds to the temperature, SOC value, and discharge power of the power battery. This invention can effectively optimize the vehicle power interruption problem under low temperature and low SOC conditions.

Description

Technical Field

[0001] This invention belongs to the field of power battery control, specifically relating to a method, system, and vehicle for controlling the discharge power of a power battery. Background Technology

[0002] As the primary energy storage component in electric vehicles, the power battery's performance at low temperatures and low SOC discharge ends, as well as power interruptions, have always been pain points for customers. With advancements in cell technology, the capacity and power performance of individual cells have increased, and within normal operating temperatures and SOC ranges, the discharge power of power batteries can generally meet customer needs. However, at low temperatures and low SOC, the discharge power of power batteries may fall below the required electric drive capacity as the temperature and SOC decrease. When the power battery's discharge end power does not match its capacity, it can easily lead to power fluctuations and power interruptions, resulting in poor user experience and safety risks.

[0003] Currently, the sustainable discharge power parameters of most electric vehicles are controlled by multiple discharge power meters. Each discharge power meter corresponds to the available power for different durations (e.g., 10s discharge power meter, 30s discharge power meter, 60s discharge power meter, etc.). When an electric vehicle is driving according to the 10s discharge power meter, it will switch to driving according to the 30s discharge power meter or the 60s discharge power meter after the integral of the actual output power over time satisfies the meter switching strategy. Under normal temperature and high SOC conditions, this meter switching strategy will not affect the normal driving of the vehicle; however, under low temperature and low SOC conditions, this meter switching strategy will trigger the undervoltage protection strategy multiple times in a row, resulting in power limitation or power interruption. The reasons are: (1) The voltage of the individual cells of the power battery varies during charging and discharging, and the lowest individual cell voltage differs greatly from the highest individual cell voltage during discharge; (2) During high-power discharge, the individual cell voltage is quickly pulled down to the discharge cutoff voltage, and the 30s discharge power meter or the 60s discharge power meter cannot be used. Summary of the Invention

[0004] The purpose of this invention is to provide a method, system, and vehicle for controlling the discharge power of a power battery, so as to effectively optimize the problem of vehicle power interruption under low temperature and low SOC conditions.

[0005] In a first aspect, the present invention provides a method for controlling the discharge power of a power battery, comprising:

[0006] Obtain the lowest single-cell temperature T of the current power battery. min Minimum unit voltage U min and SOC value.

[0007] If T minIf the operating temperature is not within the preset range, the discharge power of the power battery will be 0.

[0008] If T min If the operating temperature range is within the preset range and undervoltage is triggered, the undervoltage power limiting strategy will be executed.

[0009] If T min Within the preset operating temperature range, and without triggering undervoltage, the discharge power of the power battery is P.

[0010] Where P represents the lowest single-cell temperature T of the current power battery. min The discharge power is obtained by querying the SOC value from a preset discharge power table. The preset discharge power table is a table obtained through calibration showing the correspondence between the temperature (represented by the lowest single cell temperature), SOC value, and discharge power of a power battery.

[0011] Preferably, the calibration method for the preset discharge power meter includes:

[0012] Step 1: Select j temperature points at equal intervals within a preset operating temperature range as the discharge initiation temperature. These j temperature points include a (preset) lower operating temperature limit T. th1 and (preset) upper limit of operating temperature T th2 This is equivalent to a preset operating temperature range of [T]. th1 ,T th2 ].

[0013] The second step involves discharging the power battery with an initial temperature of the i-th temperature point and a SOC value of 100%. This is achieved by first performing multiple variable current discharge cycles, followed by constant current discharge, until the power battery stops discharging. The real-time lowest single-cell temperature T' of the power battery during the discharge process is recorded. min Real-time highest unit temperature T' max Real-time lowest unit voltage U' min Real-time discharge current I f Real-time voltage U all and real-time SOC value all Among them, the discharge current increases linearly from I1, and when it increases to I... max Time or U' min <U' cut +U th Then, the discharge current is linearly reduced to I1 to complete one variable current discharge cycle; the discharge current for constant current discharge is I2, where i takes all integers from 1 to j, I1 represents the first preset current, I2 represents the second preset current, and I2 < I1. max U' represents the preset maximum allowable current. cut Indicates T' minThe preset discharge cutoff voltage corresponding to the preset temperature range, U th This indicates the preset voltage threshold.

[0014] Third step: During the variable current discharge cycle, if the discharge current decreases and the real-time voltage U of the power battery... all A rebound occurred (i.e., U) all If the power battery discharge power P is increased, then calculate the discharge power P of the power battery. f and T' at this time min SOC all With the calculated P f Correspondingly, these values ​​are entered into the initial discharge power table; during constant current discharge, the discharge power P of the power battery is calculated. f and T' at this time min SOC all With the calculated P f Correspondingly, these should be entered into the initial version of the discharge power table.

[0015] Step 4: First, correct the error of the initial discharge power meter to obtain the second version of the discharge power meter. Then, correct the battery characteristics of the second version of the discharge power meter to obtain the preset discharge power meter.

[0016] The above calibration method first performs multiple variable current discharge cycles, then constant current discharge, and then calculates the discharge power P of the power battery. f Error correction and battery characteristic correction are performed to ensure the accuracy of discharge power, making it suitable for various operating conditions during vehicle operation.

[0017] Preferably, in the second step, during the variable current discharge cycle, if the discharge current decreases to I1 but the real-time voltage U of the power battery... all If no recovery occurs (due to weakened battery discharge capacity and low remaining SOC), the discharge current is switched to I2 for constant current discharge. During the initial and middle stages of battery discharge (corresponding to sufficient SOC), variable current discharge is initiated using I1. As the discharge current increases, the real-time battery voltage decreases; as the discharge current decreases, the real-time voltage recovers. However, at the end of battery discharge (i.e., low SOC state), if variable current discharge is still initiated using I1, the real-time voltage will continue to decrease regardless of whether the discharge current increases or decreases, without any recovery. Therefore, the discharge current needs to be reduced to I2, and constant current discharge should be performed.

[0018] Preferably, in the third step, during the variable current discharge cycle, if the discharge current decreases and the real-time voltage U of the power battery... allIf a rebound occurs, calculate the discharge power P of the power battery. f and T' at this time min SOC all With P f The corresponding method is:

[0019] If the discharge current starts to decrease, U min >U' cut +U th Then use the formula: P f =U*I max Calculate the discharge power P of the power battery. f Take the discharge current as equal to I max T' of the time min SOC all With P f Correspondingly, U represents the discharge current being equal to I. max The voltage of the power battery at that time.

[0020] If the discharge current starts to decrease, U min ≤U' cut +U th Then U will appear min =U' cut +U th The lowest discharge power within the following t seconds (i.e., U at each calculation time point within t seconds) all *I f The minimum value in the range is used as the discharge power P of the power battery. f Take the T' corresponding to the lowest discharge power. min SOC all With P f Corresponding; where t represents the preset time, 0.8≤t≤1.2.

[0021] Preferably, in the third step, when the discharge current switches to I2 (i.e., constant current discharge begins), the formula is used: P f =U all *I2, calculate the discharge power P of the power battery. f Take T' when the discharge current is equal to I2 min SOC all With P f Correspondingly; during the constant current discharge process, based on the SOC all The size is selected by choosing the calculation point, using the formula: P f =U all *I f Calculate the discharge power P of the power battery. f Take T' at each calculation point min SOC all With P f correspond.

[0022] In the third step mentioned above, the discharge power P is calculated during the process of variable current discharge, decrease in discharge current, and recovery of the real-time voltage of the power battery. f The discharge power P is also calculated during the constant current discharge process. f The obtained discharge power P f It satisfies the vehicle's drivability and power requirements without causing over-discharge of the power battery or interruption of vehicle power, making it suitable for various operating conditions during vehicle operation.

[0023] Preferably, in the fourth step, the method for correcting the error of the initial discharge power meter is as follows:

[0024] When a ≥ h, if T m SOC a The discharge power corresponding to -B is recorded in the initial discharge power table. Therefore, T in the initial discharge power table... m SOC a The discharge power corresponding to -B is entered in T. m SOC a Within the corresponding discharge power range; if T m SOC a The discharge power corresponding to -B is not recorded in the initial discharge power table, so T is calculated using linear interpolation. m SOC a The discharge power corresponding to -B, and its (i.e., the calculated T) m SOC a Enter the discharge power corresponding to -B into the initial discharge power table T. m SOC a Within the corresponding discharge power range. Where, T m This represents the m-th temperature value in the initial version of the discharge power table, SOC. a Let represent the 'a'-th SOC value in the initial discharge power table, where m takes all integer values ​​from 1 to n (m increases sequentially), n represents the total number of temperature values ​​in the initial discharge power table, 'a' takes all integer values ​​from r to h (a decreases sequentially), and r represents the total number of SOC values ​​in the initial discharge power table. r =100%, SOC1=0%, B represents the preset SOC error threshold of the power battery; if SOC2+B is equal to the w-th SOC value in the initial discharge power table, or the difference between SOC2+B and the w-th SOC value in the initial discharge power table is the smallest, or the difference between SOC2+B and the w-th and (w+1)-th SOC values ​​in the initial discharge power table is equal, then h=w.

[0025] When a < h, in T m SOC hThe corresponding discharge power and T m Linear interpolation is performed between the discharge power corresponding to SOC1 (i.e., 0) to obtain T. m SOC a The corresponding discharge power, and its (i.e., T obtained by linear interpolation) m SOC a Enter the corresponding discharge power into the initial version of the discharge power table T. m SOC a Within the corresponding discharge power grid; where a takes all integer values ​​from h-1 to 2 (a decreases sequentially).

[0026] Error corrections were made to the initial version of the discharge power table to eliminate discharge power errors caused by battery SOC errors, thereby improving the accuracy of each discharge power value in the table.

[0027] Preferably, in the fourth step, the method for correcting the battery characteristics of the second version of the discharge power meter is as follows:

[0028] At the m-th temperature value T m Among the corresponding r SOC values, if T m SOC v The corresponding discharge power is greater than T m SOC v-1 The corresponding discharge power, and greater than T m SOC v+1 The corresponding discharge power will be T m SOC v-1 The corresponding discharge power and T m SOC v+1 The average value of the corresponding discharge power is entered into the discharge power table T in the second edition. m SOC v The corresponding discharge power range (i.e., replacing the original T with this average value) m SOC v (corresponding discharge power). Where v is an integer and 2≤v≤r-1.

[0029] SOC value at the p-th p Among the corresponding n temperatures, if T d SOC p The corresponding discharge power is greater than T d-1 SOC p The corresponding discharge power, and greater than T d+1 SOC p The corresponding discharge power will be T d-1 SOC p The corresponding discharge power and T d+1 SOC pThe average value of the corresponding discharge power is entered into the discharge power table T in the second edition. d SOC p The corresponding discharge power range (i.e., replacing the original T with this average value) d SOC p (corresponding discharge power); where p takes all integers from 1 to r, and d is an integer and 2≤d≤n-1.

[0030] The battery characteristics of the second version of the discharge power table were corrected to eliminate abnormal discharge power (i.e. peak power), thus improving the accuracy of each discharge power in the discharge power table.

[0031] Preferably, if any one of conditions one through three is met, it indicates that the power battery has stopped discharging. Condition one: The real-time SOC value of the power battery during discharge is 0%; Condition two: The real-time lowest single-cell temperature T' of the power battery during discharge. min <T th1 Or the real-time highest single-cell temperature T' of the power battery max >T th2 Condition 3: The lowest real-time single-cell voltage U' of the power battery during discharge. min ≤U' cut .

[0032] Preferably, if T min Within a certain preset temperature range, and U min If the voltage is greater than the preset undervoltage threshold corresponding to the preset temperature range, then undervoltage is determined not to have been triggered. If T min Within a certain preset temperature range, and U min If the voltage is less than or equal to the preset undervoltage threshold corresponding to the preset temperature range, then an undervoltage event is determined to be triggered.

[0033] Preferably, the undervoltage power limiting strategy is as follows:

[0034] If T min Within a certain preset temperature range, and U min It is greater than the preset discharge cutoff voltage corresponding to the preset temperature range, and U min If the voltage is less than or equal to the preset undervoltage threshold corresponding to the preset temperature range, the discharge power of the power battery is A*P; where A represents the preset undervoltage power limiting coefficient.

[0035] If T min Within a certain preset temperature range, and U min If the voltage is less than or equal to the preset discharge cutoff voltage corresponding to the preset temperature range, the discharge power of the power battery will be 0.

[0036] Secondly, the present invention provides a discharge power control system for a power battery, comprising a controller configured to execute the above-described discharge power control method for the power battery.

[0037] Thirdly, the present invention provides a vehicle that includes a discharge power control system for the aforementioned power battery.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] (1) The switching strategy of multiple discharge power meters has been eliminated. Instead, a single discharge power meter is used as the basis for discharge power control. Without affecting the vehicle's drivability and power performance, the problem of vehicle power interruption under low temperature and low SOC conditions has been effectively optimized, the risk of over-discharge of the power battery has been reduced, and driving safety has been improved.

[0040] (2) Using a discharge power meter as the basis for discharge power control makes the control logic simpler, the response speed faster, and the control more precise. Attached Figure Description

[0041] Figure 1 This is a flowchart of the power battery discharge power control method in an embodiment of the present invention.

[0042] Figure 2 This is a flowchart of a pre-defined calibration method for a discharge power meter in an embodiment of the present invention. Detailed Implementation

[0043] To gain a more detailed understanding of the features and technical content of the embodiments of the present invention, the implementation of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference and illustration only and are not intended to limit the embodiments of the present invention.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0045] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0046] like Figure 1 As shown, the discharge power control method for a power battery in this embodiment of the invention includes:

[0047] Step 1: Obtain the lowest single-cell temperature T of the current power battery. min Minimum unit voltage U minAnd the SOC value, then proceed to step two.

[0048] Step 2: Determine if it is T min If the operating temperature is within the preset range, proceed to step four; otherwise, proceed to step three. The preset operating temperature range is [T]. th1 ,T th2 ], T th1 T represents the lower limit of the operating temperature. th2 This indicates the upper limit of the operating temperature. For example, T... th1 = -30℃, T th2 =55℃.

[0049] Step 3: Reduce the discharge power of the power battery to 0, and then end.

[0050] Step 4: Determine if undervoltage has been triggered. If so, proceed to Step 5; otherwise, proceed to Step 6.

[0051] In some embodiments, if T min Within a certain preset temperature range, and U min If the voltage is greater than the preset undervoltage threshold corresponding to the preset temperature range, then it is determined that undervoltage has not been triggered; if T min Within a certain preset temperature range, and U min If the voltage is less than or equal to the preset undervoltage threshold corresponding to the preset temperature range, then an undervoltage event is determined to be triggered.

[0052] The preset undervoltage threshold corresponding to the preset temperature range is obtained through calibration, and the calibration method is existing technology. The temperature is usually divided into three preset temperature ranges: [-30℃, -10℃] (i.e., temperature range one), (-10℃, 0℃] (i.e., temperature range two), and (0℃, 55℃] (i.e., temperature range three).

[0053] Step 5: Execute the undervoltage power limiting strategy, and then end.

[0054] In some embodiments, the undervoltage power limiting strategy is: if T min Within a certain preset temperature range, and U min It is greater than the preset discharge cutoff voltage corresponding to the preset temperature range, and U min If the voltage is less than or equal to the preset undervoltage threshold corresponding to the preset temperature range, the discharge power of the power battery is set to A*P. Here, A represents the preset undervoltage power limiting coefficient. If T... min Within a certain preset temperature range, and U min If the voltage is less than or equal to the preset discharge cutoff voltage corresponding to the preset temperature range, the discharge power of the power battery will be 0.

[0055] As an example, the preset discharge cutoff voltage corresponding to temperature range one is 2V, the preset undervoltage threshold corresponding to temperature range one is 2.3V, the preset discharge cutoff voltage corresponding to temperature range two is 2.2V, the preset undervoltage threshold corresponding to temperature range two is 2.5V, the preset discharge cutoff voltage corresponding to temperature range three is 2.4V, the preset undervoltage threshold corresponding to temperature range three is 2.7V, and the preset undervoltage power limiting factor A = 0.5.

[0056] Step 6: Set the discharge power of the power battery to P, then return to step 1.

[0057] Where P represents the lowest single-cell temperature T of the current power battery. min The discharge power is obtained by querying the preset discharge power table based on the SOC value. The preset discharge power table is a table that corresponds to the temperature, SOC value, and discharge power of the power battery, obtained through calibration.

[0058] In some embodiments, such as Figure 2 As shown, the preset calibration method for the discharge power meter includes:

[0059] Step 1: Select j temperature points at equal intervals within a preset operating temperature range as the discharge initiation temperature. These j temperature points include the lower limit of the operating temperature T. th1 and the upper limit of operating temperature T th2 For example, 17 temperature points are selected at equal intervals between -30℃ and 55℃, i.e., j=17. The 17 temperature points are: -30℃, -25℃, -20℃, ..., 45℃, 50℃, 55℃.

[0060] The second step involves discharging the power battery with an initial temperature of the i-th temperature point and a SOC value of 100%. This is achieved by first performing multiple variable current discharge cycles, followed by constant current discharge, until the power battery stops discharging. The real-time lowest single-cell temperature T' of the power battery during the discharge process is recorded. min Real-time highest unit temperature T' max Real-time lowest unit voltage U' min Real-time discharge current I f Real-time voltage U all and real-time SOC value all The discharge current increases linearly from I1, and when it increases to I... max Time or U' min <U' cut +U th Then, the discharge current is linearly reduced to I1 to complete one variable current discharge cycle; the discharge current for constant current discharge is I2, where i takes all integers from 1 to j, I1 represents the first preset current, I2 represents the second preset current, and I2 < I1. maxU' represents the preset maximum allowable current. cut Indicates T' min The preset discharge cutoff voltage corresponding to the preset temperature range, U th This indicates the preset voltage threshold.

[0061] In some embodiments, if any one of conditions one through three is met, it indicates that the power battery has stopped discharging. Condition one: The real-time SOC value of the power battery during discharge is 0%; Condition two: The real-time lowest single-cell temperature T' of the power battery during discharge. min <T th1 Or the real-time highest single-cell temperature T' of the power battery max >T th2 Condition 3: The lowest real-time single-cell voltage U' of the power battery during discharge. min ≤U' cut .

[0062] In some embodiments, a single variable current discharge cycle can specifically be as follows: the discharge current starts from I1 and increases linearly according to a first preset slope k1, and when it increases to I... max Time or U' min <U' cut +U th Then, the discharge current is linearly reduced to I1 according to the second preset slope k2. Where k1=|k2|.

[0063] In some embodiments, during the execution of a variable current discharge cycle, if the discharge current decreases to I1 while the real-time voltage U of the power battery decreases... all If the discharge current still does not recover, switch the discharge current to I2 and perform constant current discharge.

[0064] Third step: During the variable current discharge cycle, if the discharge current decreases and the real-time voltage U of the power battery... all If a rebound occurs, calculate the discharge power P of the power battery. f and T' at this time min SOC all With P f Correspondingly, these values ​​are entered into the initial discharge power table; during constant current discharge, the discharge power P of the power battery is calculated. f and T' at this time min SOC all With the calculated P f Correspondingly, these should be entered into the initial version of the discharge power table.

[0065] In some embodiments, during the execution of a variable current discharge cycle, if the discharge current decreases and the real-time voltage U of the power battery... all If a rebound occurs, calculate the discharge power P of the power battery.f and T' at this time min SOC all With P f The corresponding method is:

[0066] If the discharge current starts to decrease, U min >U' cut +U th This is equivalent to the discharge current increasing to I. max When the discharge current begins to decrease, the formula is used: P f =U*I max Calculate the discharge power P of the power battery. f Take the discharge current as equal to I max T' of the time min SOC all With P f Correspondingly, U represents the discharge current being equal to I. max The voltage of the power battery at that time.

[0067] If the discharge current starts to decrease, U min ≤U' cut +U th Then U will appear min =U' cut +U th The lowest discharge power within the following t seconds (i.e., U at each calculation time point within t seconds) all *I f The minimum value in the range is used as the discharge power P of the power battery. f Take the T' corresponding to the lowest discharge power. min SOC all With P f Corresponding. Where t represents the preset time, 0.8 ≤ t ≤ 1.2. For example, t = 1.

[0068] In some embodiments, when the discharge current switches to I2 (i.e., constant current discharge begins), the formula is used: P f =U all *I2, calculate the discharge power P of the power battery. f Take T' when the discharge current is equal to I2 min SOC all With P f Correspondingly; during the constant current discharge process, based on the SOC all The size is selected by choosing the calculation point, using the formula: P f =U all *I f Calculate the discharge power P of the power battery. f Take T' at each calculation point min SOC allWith P f correspond.

[0069] The fourth step is to first correct the error of the initial discharge power meter to obtain the second version of the discharge power meter. Then, the battery characteristics of the second version of the discharge power meter are corrected to obtain the preset discharge power meter.

[0070] In some embodiments, the error correction method for the initial version of the discharge power meter is as follows:

[0071] When a ≥ h, if T m SOC a The discharge power corresponding to -B is recorded in the initial discharge power table. Therefore, T in the initial discharge power table... m SOC a The discharge power corresponding to -B is entered in T. m SOC a Within the corresponding discharge power range. When a ≥ h, if T m SOC a The discharge power corresponding to -B is not recorded in the initial discharge power table, so T is calculated using linear interpolation. m SOC a The discharge power corresponding to -B, and its (i.e., the calculated T) m SOC a Enter the discharge power corresponding to -B into the initial discharge power table T. m SOC a Within the corresponding discharge power range. Where, T m This represents the m-th temperature value in the initial version of the discharge power table, SOC. a Let represent the 'a'-th SOC value in the initial discharge power table, where m takes all integer values ​​from 1 to n (m increases sequentially), n represents the total number of temperature values ​​in the initial discharge power table, 'a' takes all integer values ​​from r to h (a decreases sequentially), and r represents the total number of SOC values ​​in the initial discharge power table. r =100%, SOC1=0%, B represents the preset SOC error threshold of the power battery; if SOC2+B is equal to the w-th SOC value in the initial discharge power table, or the difference between SOC2+B and the w-th SOC value in the initial discharge power table is the smallest, or the difference between SOC2+B and the w-th and (w+1)-th SOC values ​​in the initial discharge power table is equal, then h=w.

[0072] As an example, n = 85, r = 100, B = 3%, SOC2 = 1%, then h = 5. As an example, part of the error correction here is: if the initial discharge power table records the discharge power corresponding to a temperature of -30℃ and a SOC value of 97%, then the discharge power corresponding to a temperature of -30℃ and a SOC value of 97% is filled into the discharge power cell corresponding to a temperature of -30℃ and a SOC value of 100%, and so on. If the initial discharge power table does not record the discharge power corresponding to -30℃ and 97% SOC, but records the discharge power corresponding to -30℃ and 98% SOC and the discharge power corresponding to -30℃ and 96% SOC, then linear interpolation is performed based on the discharge power corresponding to -30℃ and 97% SOC and the discharge power corresponding to -30℃ and 96% SOC to calculate the discharge power corresponding to -30℃ and 97% SOC. This calculated discharge power (i.e., the discharge power corresponding to -30℃ and 97% SOC) is then filled into the discharge power cell corresponding to -30℃ and 100% SOC in the initial discharge power table, and so on.

[0073] When a < h, in T m SOC h The corresponding discharge power and T m Linear interpolation is performed between the discharge power corresponding to SOC1 and T to obtain T. m SOC a The corresponding discharge power, and its (i.e., T obtained by linear interpolation) m SOC a Enter the corresponding discharge power into the initial version of the discharge power table T. m SOC a Within the corresponding discharge power cell. Here, 'a' takes all integer values ​​from h-1 to 2 (a decreases sequentially). Since SOC1 = 0%, T in the initial discharge power table... m The discharge power corresponding to SOC1 is 0. As an example, part of the error correction here is: linear interpolation is performed between the discharge power corresponding to -30℃ and SOC value 4% and the discharge power corresponding to -30℃ and SOC value 0%, to obtain the discharge power corresponding to -30℃ and SOC value 3%, the discharge power corresponding to -30℃ and SOC value 2%, and the discharge power corresponding to -30℃ and SOC value 1%.

[0074] In some embodiments, the battery characteristics are corrected for the second version of the discharge power meter as follows:

[0075] At the m-th temperature value T m Among the corresponding r SOC values, if T m SOC v The corresponding discharge power is greater than T m SOC v-1The corresponding discharge power, and greater than T m SOC v+1 The corresponding discharge power will be T m SOC v-1 The corresponding discharge power and T m SOC v+1 The average value of the corresponding discharge power is entered into the discharge power table T in the second edition. m SOC v The corresponding discharge power range (i.e., replacing the original T with this average value) m SOC v (corresponding discharge power). Where v is an integer and 2≤v≤r-1. As an example, part of the battery characteristic correction is: if T m SOC 50 The corresponding discharge power is greater than T m SOC 49 The corresponding discharge power, and greater than T m SOC 51 The corresponding discharge power will be T m SOC 49 The corresponding discharge power and T m SOC 51 The average value of the corresponding discharge power is entered into the discharge power table T in the second edition. m SOC 50 Within the corresponding discharge power range.

[0076] SOC value at the p-th p Among the corresponding n temperatures, if T d SOC p The corresponding discharge power is greater than T d-1 SOC p The corresponding discharge power, and greater than T d+1 SOC p The corresponding discharge power will be T d-1 SOC p The corresponding discharge power and T d+1 SOC p The average value of the corresponding discharge power is entered into the discharge power table T in the second edition. d SOC p The corresponding discharge power range (i.e., replacing the original T with this average value) d SOC p (Corresponding discharge power). Here, p takes all integer values ​​from 1 to r, and d is an integer where 2 ≤ d ≤ n-1. As an example, part of the battery characteristic correction is: if T 10 SOC p The corresponding discharge power is greater than T9 and SOC. pThe corresponding discharge power, and greater than T 11 SOC p The corresponding discharge power will be T9 and SOC. p The corresponding discharge power and T 11 SOC p The average value of the corresponding discharge power is entered into the discharge power table T in the second edition. 10 SOC p Within the corresponding discharge power range.

[0077] An example preset discharge power table is shown in Table 1.

[0078] Table 1

[0079] -30℃ -29℃ -28℃ … 53℃ 54℃ 55℃ 0％ 0 0 0 0 0 0 0 1％ 2％ 3％ … 98％ 99％ 100％

[0080] This invention also provides a power battery discharge power control system, which includes a controller configured to execute the power battery discharge power control method described above.

[0081] This invention also provides a vehicle that includes the discharge power control system of the aforementioned power battery.

[0082] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for discharging power control of a power battery, characterized in that, The application relates to a preset discharge power table and a calibration method thereof. obtaining a lowest single cell temperature T of the current power battery min , a lowest single cell voltage U min and a SOC value; If T min If the working temperature is not in the preset working temperature range, the discharge power of the power battery is 0. If T min In a preset working temperature range, and triggering under-voltage, then execute under-voltage power limiting strategy; If T min Within a preset working temperature range, and without triggering under-voltage, the discharge power of the power battery is P; Wherein, P represents the discharge power obtained by querying the preset discharge power table according to the minimum single cell temperature T min of the current power battery, SOC value and the discharge power; and the preset discharge power table is a correspondence table of the temperature, SOC value and the discharge power of the power battery obtained through calibration. The calibration method of the preset discharge power table comprises the following steps: The first step is to select j temperature points as the starting temperature of discharging at equal intervals in a preset working temperature range; wherein, the j temperature points contain the lower limit of working temperature T th1 and the upper limit of working temperature T th2 ; The second step is to discharge the power battery with the initial temperature being the i-th temperature point and the SOC value being 100%, first performing multiple variable-current discharge cycles, then performing constant-current discharge, until the power battery stops discharging, and recording the real-time lowest single battery temperature T' min , the real-time highest single battery temperature T' max , the real-time lowest single battery voltage U' min , the real-time discharge current I f , the real-time voltage U all , and the real-time SOC value SOC all ; wherein the discharge current is linearly increased from I1, and when it is increased to I max or U' min <U' cut + U th , it is linearly reduced to I1 for a variable-current discharge cycle; the discharge current of the constant-current discharge is I2, i is sequentially all integers from 1 to j, I1 represents a first preset current, I2 represents a second preset current, I2 max represents a preset maximum allowable current, U' cut represents a preset discharge cutoff voltage corresponding to the preset temperature interval to which T' min belongs, U th represents a preset voltage threshold value. Third step, in the process of executing variable current discharge cycle, if the discharge current decreases and U all appears rebound, then calculate the discharge power P f of the power battery, and fill in the initial version of the discharge power table corresponding to T' min , SOC all and P f at this time; in the process of executing constant current discharge, calculate the discharge power P f of the power battery, and fill in the initial version of the discharge power table corresponding to T' min , SOC all and P f at this time; In the fourth step, the error of the first edition discharge power table is corrected to obtain a second edition discharge power table, and then the second edition discharge power table is corrected according to the battery characteristics to obtain the preset discharge power table.

2. The method of claim 1, wherein: In the second step, during the execution of the variable current discharge cycle, if the discharge current is reduced to I1 but U all does not yet rise, the discharge current is switched to I2 and a constant current discharge is executed.

3. The discharge power control method of the power battery according to claim 1, characterized in that: In the third step, during the execution of the variable current discharge cycle, if the discharge current decreases and U all If a rebound occurs, calculate the discharge power P of the power battery. f and T' at this time min SOC all With P f The corresponding method is: If the discharge current starts to decrease U min > U' cut + U th , then the discharge power P f of the power battery is calculated using the formula: P max = U * I f , T' max , SOC min and P all corresponding to the discharge current equal to I f , and U represents the voltage of the power battery when the discharge current is equal to I max . If the discharge current starts to decrease, U min ≤ U' cut + U th , then U min = U' cut + U th The minimum discharge power in the next t seconds is taken as the discharge power P f of the power battery, and T' min , SOC all and P f corresponding to the minimum discharge power are taken; wherein t represents a preset time, 0.8 ≤ t ≤ 1.

2. In the third step, when the discharge current switches to I2, the formula is used: P f = U all *I2, calculate the discharge power P of the power battery. f Take T' when the discharge current is equal to I2 min SOC all With P f Correspondingly; during the constant current discharge process, based on the SOC all The size is selected by choosing the calculation point, using the formula: P f = U all *I f Calculate the discharge power P of the power battery. f Take T' at each calculation point min SOC all With P f correspond.

4. The discharge power control method of the power battery according to claim 1, characterized in that: In the fourth step, the error of the first edition discharge power table is corrected to obtain a second edition discharge power table, and then the second edition discharge power table is corrected according to the battery characteristics to obtain the preset discharge power table. When a ≥ h, if T m SOC a The discharge power corresponding to -B is recorded in the initial discharge power table. Therefore, T in the initial discharge power table... m SOC a -B corresponds to the discharge power in T. m SOC a Within the corresponding discharge power range; if T m SOC a The discharge power corresponding to -B is not recorded in the initial discharge power table, so T is calculated using linear interpolation. m SOC a The discharge power corresponding to -B is entered into the initial discharge power table T. m SOC a The corresponding discharge power grid; where T m This represents the m-th temperature value in the initial version of the discharge power table, SOC. a Let represent the a-th SOC value in the initial discharge power table, where m takes all integers from 1 to n, n represents the total number of temperature values ​​in the initial discharge power table, and a takes all integers from r to h, where r represents the total number of SOC values ​​in the initial discharge power table. r =100%, SOC1=0%, B represents the preset SOC error threshold of the power battery; if SOC2+B is equal to the w-th SOC value in the initial discharge power table, or the difference between SOC2+B and the w-th SOC value in the initial discharge power table is the smallest, or the difference between SOC2+B and the w-th and (w+1)-th SOC values ​​in the initial discharge power table is equal, then h=w; When a < h, in T m , SOC h The corresponding discharge power and T m , SOC1 corresponding to the discharge power between linear interpolation, T m , SOC a The corresponding discharge power is filled in the initial discharge power table T m , SOC a The corresponding discharge power grid; wherein, a takes all integers from h-1 to 2 in turn; In the fourth step, the error of the first edition discharge power table is corrected to obtain a second edition discharge power table, and then the second edition discharge power table is corrected according to the battery characteristics to obtain the preset discharge power table. At the m-th temperature value T m Of the corresponding r SOC values, if T m SOC v The corresponding discharge power is greater than T m SOC v-1 The corresponding discharge power, and greater than T m SOC v+1 The corresponding discharge power will be T m SOC v-1 The corresponding discharge power and T m SOC v+1 The average value of the corresponding discharge power is entered into the discharge power table T in the second edition. m SOC v Within the corresponding discharge power grid; where v is an integer and 2≤v≤r-1; at the pth SOC value SOC p Among the corresponding n temperatures, if T d , SOC p corresponding discharge power is greater than T d-1 , SOC p corresponding discharge power, and greater than T d+1 , SOC p corresponding discharge power, then T d-1 , SOC p corresponding discharge power and T d+1 , SOC p corresponding discharge power are filled in the second edition discharge power table T d , SOC p corresponding discharge power grid; wherein p takes all integers from 1 to r in turn, d is an integer and 2≤d≤n-1.

5. The method of claim 1, wherein: If any one of the conditions one to three is met, the power battery stops discharging; wherein, Condition one: the real-time SOC value of the power battery during the discharging process is 0%; Condition two: the real-time minimum single cell temperature T' of the power battery during discharging min <T th1 , or the real-time maximum single cell temperature T' of the power battery max >T th2 ; Condition three: the real-time minimum single cell voltage U' of the power battery during discharging process min ≤ U' cut .

6. The discharge power control method of the power battery according to any one of claims 1 to 5, characterized in that: If T min In a certain preset temperature interval, and U min greater than the preset undervoltage threshold corresponding to the preset temperature interval, it is determined that the undervoltage is not triggered. If T min In a certain preset temperature interval, and U min Less than or equal to the preset undervoltage threshold corresponding to the preset temperature interval, it is determined that the undervoltage is triggered.

7. The method of claim 6, wherein, The under-voltage limited power strategy is: If T min Within a preset temperature range, and U min greater than a preset discharge cutoff voltage corresponding to the preset temperature range, and U min less than or equal to a preset undervoltage threshold corresponding to the preset temperature range, the discharge power of the power battery is A*P; wherein A represents a preset undervoltage limited power coefficient. If T min In a preset temperature interval, and U min Less than or equal to the preset discharge cutoff voltage corresponding to the preset temperature interval, the discharge power of the power battery is 0.

8. A discharge power control system for a power cell, comprising a controller, characterized by: The controller is configured to execute the discharge power control method of the power battery according to any one of claims 1 to 7.

9. A vehicle characterized by: The application further relates to a discharge power control system of a power battery comprising the discharge power control system according to claim 8.

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