Discharge power control method and system of power battery and vehicle

Abstract

The invention discloses a discharging power control method and system of a power battery and a vehicle. The discharging power control method comprises the steps that the lowest monomer temperature Tmin, the lowest monomer voltage Umin and the SOC value of the current power battery are obtained; if Tmin is not in the preset working temperature interval, the discharge power of the power battery is made to be 0; if the Tmin is in the preset working temperature interval and under-voltage is triggered, executing an under-voltage power limiting strategy; and if the Tmin is in the preset working temperature interval and the undervoltage is not triggered, enabling the discharge power of the power battery to be P. Wherein P represents the discharge power obtained by inquiring a preset discharge power table according to the lowest monomer temperature Tmin and the SOC value of the current power battery, and the preset discharge power table is a corresponding relation table of the temperature, the SOC value and the discharge power of the power battery obtained through calibration. By adopting the method, the problem of power interruption of the vehicle under the conditions of low temperature and low SOC can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the field of power battery control, and in particular relates to a discharge power control method, system and vehicle of a power battery. Background Art

[0002] As the main energy storage component in electric vehicles, power batteries have always been a pain point for customers due to their power performance and power interruption at the end of low temperature and low SOC discharge. With the development of battery cell technology, the capacity of battery cells has increased, and the power performance of battery cells has increased. At room temperature and in the normal SOC usage range, the discharge power of power batteries can mostly meet the needs of customers; however, at low temperatures and low SOC, as the temperature and SOC decrease, the discharge power of power batteries will be lower than the required capacity of electric drive. When the power at the end of power battery discharge does not match the power battery capacity, it is easy to cause power fluctuations and power interruption, resulting in poor user experience and safety risks.

[0003] At present, the sustainable discharge power parameters of most electric vehicles are controlled by multiple discharge power meters, each of which corresponds to available power of different durations (such as 10s discharge power meter, 30s discharge power meter, 60s discharge power meter, etc.). When the electric vehicle is driving according to the 10s discharge power meter, when the integral of the actual output power over time satisfies the meter switching strategy, it will switch to driving according to the 30s discharge power meter or the 60s discharge power meter. 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 succession, resulting in power limitation or power interruption. The reasons are: (1) The cell voltage of the power battery varies during the charging and discharging process, and the lowest cell voltage and the highest cell voltage differ greatly during discharge; (2) During high-power discharge, the cell voltage is quickly pulled down to the discharge cut-off voltage, and the 30s discharge power meter or the 60s discharge power meter cannot be used. Summary of the invention

[0004] The object of the present invention is to provide a discharge power control method, system and vehicle of a power battery, so as to effectively optimize the vehicle power interruption problem 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] Get the current minimum cell temperature T of the power battery min , minimum single cell 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 is set to 0.

[0008] If T min Within the preset operating temperature range, if undervoltage is triggered, the undervoltage power limiting strategy is 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 cell temperature T of the current power battery. min , the SOC value queries the preset discharge power table to obtain the discharge power, and the preset discharge power table is a correspondence table of the power battery temperature (represented by the lowest cell temperature), the SOC value and the discharge power obtained through calibration.

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

[0012] The first step is to select j temperature points at equal intervals within the preset working temperature range as the starting temperature of the discharge. Among them, the j temperature points include the (preset) lower limit of the working temperature T th1 and the (preset) upper operating temperature limit T th2 . This is equivalent to the preset operating temperature range of [T th1 ,T th2 ].

[0013] The second step is to discharge the power battery with the starting temperature being the i-th temperature point and the SOC value being 100%. First, multiple variable current discharge cycles are performed, and then constant current discharge is performed 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 maximum monomer temperature T' max , Real-time minimum single cell voltage U' min , Real-time discharge current I f , real-time voltage U all And real-time SOC value SOC all ; Among them, the discharge current increases linearly from I1, and when it increases to I max When or U' min <U' cut +U th When the discharge current is linearly reduced to I1, it is a variable current discharge cycle; the discharge current of the constant current discharge is I2, i takes all integers from 1 to j in sequence, I1 represents the first preset current, I2 represents the second preset current, I2<I1, I max Indicates the preset maximum allowable current, U' cut Indicates that T' minThe preset discharge cut-off voltage corresponding to the preset temperature range, U th Indicates the preset voltage threshold.

[0014] Step 3: During the variable current discharge cycle, if the discharge current decreases and the real-time voltage U all There is a rebound (U all Increase), then calculate the discharge power P of the power battery f , and T' min , SOC all The calculated P f Correspondingly, fill in the initial version of the discharge power table together; during the constant current discharge process, calculate the discharge power P of the power battery f , and T' min , SOC all The calculated P f Correspondingly, fill in the first edition discharge power table together.

[0015] In the fourth step, the error of the first version of the discharge power table is corrected to obtain the second version of the discharge power table, and then the battery characteristics of the second version of the discharge power table are corrected to obtain the preset discharge power table.

[0016] In the above calibration method, multiple variable current discharge cycles are performed first, and then constant current discharge is performed, and the calculated discharge power P of the power battery is f Error correction and battery characteristic correction are performed to ensure the accuracy of discharge power, which is suitable for various working conditions during vehicle driving.

[0017] Preferably, in the second step, during the variable current discharge cycle, if the discharge current is reduced to I1 but the real-time voltage U all If there is still no recovery (caused by the weakening of the power battery's discharge capacity and the low remaining SOC), the discharge current is switched to I2 to perform constant current discharge. In the early and middle stages of the power battery discharge (corresponding to when the SOC is sufficient), variable current discharge is performed with I1 as the discharge current starting point. When the discharge current increases, the real-time voltage of the power battery will decrease, and when the discharge current decreases, the real-time voltage of the power battery will rebound; at the end of the power battery discharge (i.e., low SOC state), if variable current discharge is still performed with I1 as the discharge current starting point, when the discharge current increases, the real-time voltage of the power battery will decrease, and when the discharge current decreases, the real-time voltage of the power battery will continue to decrease and will not rebound; therefore, the discharge current needs to be reduced to I2 and constant current discharge is performed.

[0018] Preferably, in the third step, during the variable current discharge cycle, if the discharge current decreases and the real-time voltage U allIf the power rises, calculate the discharge power P of the power battery. f , and T' 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 equal to I max T' min , SOC all With P f Correspondingly, U represents the discharge current equal to I max The voltage of the power battery.

[0020] If the discharge current starts to decrease, U min ≤U' cut +U th , then U will appear min =U' cut +U th The minimum discharge power within the next t seconds (i.e., the U at each calculation time point within t seconds) all *I f The minimum value of f , take T' corresponding to the minimum discharge power min , SOC all With P f Corresponding; wherein, t represents the preset time, 0.8≤t≤1.2.

[0021] Preferably, in the third step, when the discharge current is switched to I2 (i.e., constant current discharge is started), the formula: 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 Corresponding; During the constant current discharge process, according to SOC all The size of the calculation point is selected, 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 above, the discharge power P is calculated during the variable current discharge, the discharge current decreases, and the real-time voltage of the power battery rises. f , the discharge power P is also calculated during the constant current discharge process f , the discharge power P obtained f It not only meets the vehicle's drivability and power requirements, but also will not cause over-discharge of the power battery and vehicle power interruption. It is suitable for various working conditions during vehicle driving.

[0023] Preferably, in the fourth step, the method of performing error correction on the initial version of the discharge power meter is:

[0024] When a ≥ h, if T m , SOC a -B is recorded in the first edition discharge power table, then replace T m , SOC a -B corresponding discharge power fill in T m , SOC a The corresponding discharge power grid; if T m , SOC a -B corresponding to the discharge power is not recorded in the first edition of the discharge power table, the linear interpolation method is used to calculate T m , SOC a -B corresponding to the discharge power, and the calculated T m , SOC a -B corresponding to the discharge power) is filled in the initial version of the discharge power table T m , SOC a The corresponding discharge power is in the grid. Among them, T m Indicates the mth temperature value in the first version of the discharge power table, SOC a represents the ath SOC value in the first version of the discharge power table, m is all integers from 1 to n (m increases in sequence), n represents the total number of temperature values ​​in the first version of the discharge power table, a is all integers from r to h (a decreases in sequence), r represents the total number of SOC values ​​in the first version of the discharge power table, SOC r =100%, SOC1=0%, B represents the preset power battery SOC error threshold; if SOC2+B is equal to the wth SOC value in the initial version of the discharge power table, or the difference between SOC2+B and the wth SOC value in the initial version of the discharge power table is the smallest, or the difference between SOC2+B and the wth SOC value and the w+1th SOC value in the initial version of the discharge power table is equal, then h=w.

[0025] When a<h, at T m , SOC hThe corresponding discharge power and T m , and the discharge power corresponding to SOC1 (i.e. 0) are linearly interpolated to obtain T m , SOC a The corresponding discharge power is then converted into the linear interpolated T m , SOC a The corresponding discharge power) is filled in the initial version of the discharge power table T m , SOC a The corresponding discharge power grid; wherein a takes all integers from h-1 to 2 in sequence (a decreases in sequence).

[0026] The error correction of the initial version of the discharge power meter is performed to eliminate the discharge power error caused by the battery SOC error, thereby improving the accuracy of each discharge power in the discharge power meter.

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

[0028] At the mth 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 is greater than T m , SOC v+1 The corresponding discharge power is T m , SOC v-1 The corresponding discharge power and T m , SOC v+1 The corresponding average value of discharge power is filled in the second version of the discharge power table T m , SOC v The corresponding discharge power grid (that is, use the average value to replace the original T m , SOC v The corresponding discharge power). Wherein, v is an integer and 2≤v≤r-1.

[0029] At the pth SOC value SOC 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 is greater than T d+1 , SOC p The corresponding discharge power is T d-1 , SOC p The corresponding discharge power and T d+1 , SOC pThe corresponding average value of discharge power is filled in the second version of the discharge power table T d , SOC p The corresponding discharge power grid (that is, use the average value to replace the original T d , SOC p Corresponding discharge power); wherein p is all integers from 1 to r in sequence, d is an integer and 2≤d≤n-1.

[0030] The battery characteristics of the second version of the discharge power meter are corrected to eliminate abnormal discharge power (ie, peak power), thereby improving the accuracy of each discharge power in the discharge power meter.

[0031] Preferably, if any one of conditions 1 to 3 is met, it means that the power battery stops discharging. Among them, condition 1: the real-time SOC value of the power battery during discharge is 0%; condition 2: the real-time minimum cell temperature T' of the power battery during discharge min <T th1 , or the real-time maximum cell temperature T' of the power battery max >T th2 ; Condition 3: The real-time minimum cell voltage U' of the power battery during discharge min ≤U' cut .

[0032] Preferably, if T min In a preset temperature range, and U min If T is greater than the preset undervoltage threshold corresponding to the preset temperature range, it is determined that undervoltage is not triggered. min In a preset temperature range, and U min If the temperature is less than or equal to a preset undervoltage threshold corresponding to the preset temperature range, it is determined that undervoltage is triggered.

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

[0034] If T min In a preset temperature range, and U min is greater than the preset discharge cut-off voltage corresponding to the preset temperature range, and U min If the temperature 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; wherein A represents the preset undervoltage limit power coefficient.

[0035] If T min In a preset temperature range, and U min If the temperature is less than or equal to the preset discharge cut-off voltage corresponding to the preset temperature range, the discharge power of the power battery is set to 0.

[0036] In a second aspect, the present invention provides a discharge power control system for a power battery, which includes a controller configured to execute the above-mentioned discharge power control method for the power battery.

[0037] In a third aspect, the present invention provides a vehicle comprising the above-mentioned discharge power control system of the power battery.

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

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

[0040] (2) Using a discharge power meter as the basis for discharge power control, the control logic is simpler, the response speed is faster, and the control is more precise. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The figure is a flow chart of a method for controlling the discharge power of a power battery in an embodiment of the present invention.

[0042] Figure 2 The figure is a flow chart of a calibration method of a discharge power meter preset in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present invention, the implementation of the embodiments of the present invention is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference 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 those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0045] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be 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 of the power battery in the embodiment of the present invention includes:

[0047] Step 1: Get the lowest cell temperature T of the current power battery min , minimum single cell voltage U minand SOC value, then proceed to step 2.

[0048] Step 2: Determine whether T min If it is within the preset working temperature range, then go to step 4, otherwise go to step 3. The preset working temperature range is [T th1 ,T th2 ], T th1 Indicates the lower limit of operating temperature, T th2 Indicates the upper limit of the operating temperature. As an example, T th1 =-30℃, T th2 =55℃.

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

[0050] Step 4: Determine whether undervoltage is triggered. If yes, execute step 5; otherwise, execute step 6.

[0051] In some embodiments, if T min In a preset temperature range, and U min If the undervoltage threshold value is greater than the preset temperature range, it is determined that the undervoltage is not triggered. min In a preset temperature range, and U min If the temperature is less than or equal to a preset undervoltage threshold corresponding to the preset temperature range, it is determined that undervoltage is triggered.

[0052] The preset undervoltage threshold corresponding to the preset temperature interval is obtained by calibration, and the calibration method belongs to the prior art. The temperature is usually divided into three preset temperature intervals, which are: [-30°C, -10°C] (i.e., temperature interval 1), (-10°C, 0°C] (i.e., temperature interval 2), and (0°C, 55°C] (i.e., temperature interval 3).

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

[0054] In some embodiments, the undervoltage power limit strategy is: if T min In a preset temperature range, and U min is greater than the preset discharge cut-off 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 limit power coefficient. min In a preset temperature range, and U min If the temperature is less than or equal to the preset discharge cut-off voltage corresponding to the preset temperature range, the discharge power of the power battery is set to 0.

[0055] As an example, the preset discharge cut-off voltage corresponding to temperature interval one is 2V, the preset undervoltage threshold corresponding to temperature interval one is 2.3V, the preset discharge cut-off voltage corresponding to temperature interval two is 2.2V, the preset undervoltage threshold corresponding to temperature interval two is 2.5V, the preset discharge cut-off voltage corresponding to temperature interval three is 2.4V, the preset undervoltage threshold corresponding to temperature interval three is 2.7V, and the preset undervoltage limit power coefficient A=0.5.

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

[0057] Where P represents the lowest cell temperature T of the current power battery. min The preset discharge power table is a table of corresponding relationships between the temperature, SOC value and discharge power of the power battery obtained through calibration.

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

[0059] The first step is to select j temperature points at equal intervals within the preset working temperature range as the starting temperature of discharge. Among them, the j temperature points include the lower limit of the working temperature T th1 And the upper limit of operating temperature T th2 For example, 17 temperature points are selected at equal intervals between -30°C and 55°C, that is, j=17, and the 17 temperature points are: -30°C, -25°C, -20°C, ..., 45°C, 50°C, 55°C.

[0060] The second step is to discharge the power battery with the starting temperature being the i-th temperature point and the SOC value being 100%. First, multiple variable current discharge cycles are performed, and then constant current discharge is performed 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 maximum monomer temperature T' max , Real-time minimum single cell voltage U' min , Real-time discharge current I f , real-time voltage U all And real-time SOC value SOC all The discharge current increases linearly from I1 to I max When or U' min <U' cut +U th When the discharge current is linearly reduced to I1, it is a variable current discharge cycle; the discharge current of the constant current discharge is I2, i takes all integers from 1 to j in sequence, I1 represents the first preset current, I2 represents the second preset current, I2<I1, I maxIndicates the preset maximum allowable current, U' cut Indicates that T' min The preset discharge cut-off voltage corresponding to the preset temperature range, U th Indicates the preset voltage threshold.

[0061] In some embodiments, if any one of conditions 1 to 3 is met, it means that the power battery stops discharging. Condition 1: The real-time SOC value of the power battery during discharge is 0%; Condition 2: The real-time minimum cell temperature T' of the power battery during discharge is min <T th1 , or the real-time maximum cell temperature T' of the power battery max >T th2 ; Condition 3: The real-time minimum cell voltage U' of the power battery during discharge min ≤U' cut .

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

[0063] In some embodiments, during the variable current discharge cycle, if the discharge current is reduced to I1 and the real-time voltage U all If there is still no recovery, the discharge current is switched to I2 to perform constant current discharge.

[0064] Step 3: During the variable current discharge cycle, if the discharge current decreases and the real-time voltage U all If the power rises, calculate the discharge power P of the power battery. f , and T' min , SOC all With P f Correspondingly, fill in the initial version of the discharge power table together; during the constant current discharge process, calculate the discharge power P of the power battery f , and T' min , SOC all The calculated P f Correspondingly, fill in the first edition discharge power table together.

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

[0066] If the discharge current starts to decrease, U min >U' cut +U th , which is equivalent to the discharge current increasing to I max When the discharge current starts 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 equal to I max T' min , SOC all With P f Correspondingly, U represents the discharge current equal to I max The voltage of the power battery.

[0067] If the discharge current starts to decrease, U min ≤U' cut +U th , then U will appear min =U' cut +U th The minimum discharge power within the next t seconds (i.e., the U at each calculation time point within t seconds) all *I f The minimum value of f , take T' corresponding to the minimum discharge power min , SOC all With P f Corresponding. Wherein, t represents a preset time, 0.8≤t≤1.2. As an example, t=1.

[0068] In some embodiments, when the discharge current is switched to I2 (i.e., constant current discharge is started), the formula: 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 Corresponding; During the constant current discharge process, according to SOC all The size of the calculation point is selected, 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 firstly perform error correction on the first version of the discharge power table to obtain the second version of the discharge power table, and then perform battery characteristic correction on the second version of the discharge power table to obtain the preset discharge power table.

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

[0071] When a ≥ h, if T m , SOC a -B is recorded in the first edition discharge power table, then replace T m , SOC a -B corresponding discharge power fill in T m , SOC a The corresponding discharge power is within the grid. When a≥h, if T m , SOC a -B corresponding to the discharge power is not recorded in the first edition of the discharge power table, the linear interpolation method is used to calculate T m , SOC a -B corresponding to the discharge power, and the calculated T m , SOC a -B corresponding to the discharge power) is filled in the initial version of the discharge power table T m , SOC a The corresponding discharge power is in the grid. Among them, T m Indicates the mth temperature value in the first version of the discharge power table, SOC a represents the ath SOC value in the first version of the discharge power table, m is all integers from 1 to n (m increases in sequence), n represents the total number of temperature values ​​in the first version of the discharge power table, a is all integers from r to h (a decreases in sequence), r represents the total number of SOC values ​​in the first version of the discharge power table, SOC r =100%, SOC1=0%, B represents the preset power battery SOC error threshold; if SOC2+B is equal to the wth SOC value in the initial version of the discharge power table, or the difference between SOC2+B and the wth SOC value in the initial version of the discharge power table is the smallest, or the difference between SOC2+B and the wth SOC value and the w+1th SOC value in the initial version of the 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 discharge power corresponding to the temperature of -30°C and the SOC value of 97% is recorded in the first edition of the discharge power table, then the discharge power corresponding to the temperature of -30°C and the SOC value of 97% is filled in the discharge power corresponding to the temperature of -30°C and the SOC value of 100%, and so on. If the initial edition of the discharge power table does not record the discharge power corresponding to a temperature of -30°C and a SOC value of 97%, but records the discharge power corresponding to a temperature of -30°C and a SOC value of 98% and the discharge power corresponding to a temperature of -30°C and a SOC value of 96%, then linear interpolation is performed based on the discharge power corresponding to a temperature of -30°C and a SOC value of 98% and the discharge power corresponding to a temperature of -30°C and a SOC value of 96%, and the discharge power corresponding to -30°C and a SOC value of 97% is calculated, and the discharge power (i.e. the calculated discharge power corresponding to -30°C and a SOC value of 97%) is filled in the discharge power cell corresponding to -30°C and a SOC value of 100% in the initial edition of the discharge power table, and so on.

[0073] When a<h, at T m , SOC h The corresponding discharge power and T m , and the discharge power corresponding to SOC1 are linearly interpolated to obtain T m , SOC a The corresponding discharge power is then converted into the linear interpolated T m , SOC a The corresponding discharge power) is filled in the initial version of the discharge power table T m , SOC a The corresponding discharge power grid. Where a is all integers from h-1 to 2 (a decreases in sequence). Since SOC1 = 0%, T in the initial version of the discharge power table m , the discharge power corresponding to SOC1 is 0. As an example, part of the error correction here is: linearly interpolate between the discharge power corresponding to -30°C and SOC value 4% and the discharge power corresponding to -30°C and SOC value 0%, and obtain the discharge power corresponding to -30°C and SOC value 3%, the discharge power corresponding to -30°C and SOC value 2%, and the discharge power corresponding to -30°C and SOC value 1%.

[0074] In some embodiments, the method of correcting the battery characteristics of the second version of the discharge power table is:

[0075] At the mth 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 is greater than T m , SOC v+1 The corresponding discharge power is T m , SOC v-1 The corresponding discharge power and T m , SOC v+1 The corresponding average value of discharge power is filled in the second version of the discharge power table T m , SOC v The corresponding discharge power grid (that is, use the average value to replace the original T m , SOC v The 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 is greater than T m , SOC 51 The corresponding discharge power is T m , SOC 49 The corresponding discharge power and T m , SOC 51 The corresponding average value of discharge power is filled in the second version of the discharge power table T m , SOC 50 The corresponding discharge power grid.

[0076] At the pth SOC value SOC 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 is greater than T d+1 , SOC p The corresponding discharge power is T d-1 , SOC p The corresponding discharge power and T d+1 , SOC p The corresponding average value of discharge power is filled in the second version of the discharge power table T d , SOC p The corresponding discharge power grid (that is, use the average value to replace the original T d , SOC p The corresponding discharge power). Where p is all integers from 1 to r, d is an integer and 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 is greater than T 11 , SOC p The corresponding discharge power is T9, SOC p The corresponding discharge power and T 11 , SOC p The corresponding average value of discharge power is filled in the second version of the discharge power table T 10 , SOC p The corresponding discharge power grid.

[0077] An exemplary 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] An embodiment of the present invention further provides a discharge power control system for a power battery, which includes a controller configured to execute the above-mentioned discharge power control method for the power battery.

[0081] An embodiment of the present invention further provides a vehicle, which includes the above-mentioned discharge power control system of the power battery.

[0082] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for controlling the discharge power of a power battery, characterized in that: include: Get the current minimum cell temperature T of the power battery min , minimum single cell voltage U min and SOC value; If T min If the temperature is not within the preset operating temperature range, the discharge power of the power battery is set to 0; If T min Within the preset operating temperature range, if undervoltage is triggered, 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 P; Where P represents the lowest cell temperature T of the current power battery. min , and the SOC value queries a preset discharge power table to obtain the discharge power, wherein the preset discharge power table is a correspondence table of the temperature, SOC value and discharge power of the power battery obtained through calibration.

2. The method for controlling the discharge power of a power battery according to claim 1, characterized in that: The calibration method of the preset discharge power meter includes: The first step is to select j temperature points at equal intervals within the preset working temperature range as the starting temperature of the discharge; wherein the j temperature points include the lower limit of the working temperature T th1 And the upper limit of operating temperature T th2 ; The second step is to discharge the power battery with the starting temperature being the i-th temperature point and the SOC value being 100%. First, multiple variable current discharge cycles are performed, and then constant current discharge is performed 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 maximum monomer temperature T' max , Real-time minimum single cell voltage U' min , Real-time discharge current I f , real-time voltage U all And real-time SOC value SOC all ; Among them, the discharge current increases linearly from I1, and when it increases to I max When or U' min <U' cut +U th When the constant current discharge is performed, the discharge current is linearly reduced to I1, which is a variable current discharge cycle; the discharge current of the constant current discharge is I2, i takes all integers from 1 to j in sequence, I1 represents the first preset current, I2 represents the second preset current, I2<I1, I max Indicates the preset maximum allowable current, U' cut Indicates that T' min The preset discharge cut-off voltage corresponding to the preset temperature range, U th Indicates a preset voltage threshold; Step 3: During the variable current discharge cycle, if the discharge current decreases and U all If the power rises, calculate the discharge power P of the power battery. f , and T' min , SOC all With P f Correspondingly, fill in the first version of the discharge power table; during the constant current discharge process, calculate the discharge power P of the power battery f , and T' min , SOC all With P f Correspondingly, fill in the first edition discharge power table; In the fourth step, the error of the first version of the discharge power table is corrected to obtain the second version of the discharge power table, and then the battery characteristics of the second version of the discharge power table are corrected to obtain the preset discharge power table.

3. The method for controlling the discharge power of a power battery according to claim 2, characterized in that: In the second step, during the variable current discharge cycle, if the discharge current decreases to I1 but U all If there is still no recovery, the discharge current is switched to I2 to perform constant current discharge.

4. The method for controlling the discharge power of a power battery according to claim 2, characterized in that: In the third step, during the variable current discharge cycle, if the discharge current decreases and U all If the power rises, calculate the discharge power P of the power battery. f , and T' min , SOC all With P f The corresponding method is: 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 equal to I max T' min , SOC all With P f Correspondingly, U represents the discharge current equal to I max The voltage of the power battery at the time; If the discharge current starts to decrease, U min ≤U' cut +U th , then U will appear min =U' cut +U th The minimum discharge power within t seconds is taken as the discharge power P of the power battery. f , take T' corresponding to the minimum discharge power min , SOC all With P f Corresponding; where t represents the preset time, 0.8≤t≤1.2; In the third step, when the discharge current is switched to I2, the formula: 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 Corresponding; During the constant current discharge process, according to SOC all The size of the calculation point is selected, 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.

5. The method for controlling the discharge power of a power battery according to claim 2, characterized in that: In the fourth step, the method of performing error correction on the initial version of the discharge power meter is as follows: When a ≥ h, if T m , SOC a -B is recorded in the first edition discharge power table, then replace T m , SOC a -B corresponding discharge power fill in T m , SOC a The corresponding discharge power grid; if T m , SOC a -B corresponding to the discharge power is not recorded in the first edition of the discharge power table, the linear interpolation method is used to calculate T m , SOC a -B corresponding to the discharge power, and fill it in the initial version of the discharge power table T m , SOC a The corresponding discharge power grid; where T m Indicates the mth temperature value in the first version of the discharge power table, SOC a represents the ath SOC value in the first version of the discharge power table, m is an integer from 1 to n, n represents the total number of temperature values ​​in the first version of the discharge power table, a is an integer from r to h, r represents the total number of SOC values ​​in the first version of the discharge power table, SOC r =100%, SOC1=0%, B represents the preset power battery SOC error threshold; if SOC2+B is equal to the wth SOC value in the initial version of the discharge power table, or the difference between SOC2+B and the wth SOC value in the initial version of the discharge power table is the smallest, or the difference between SOC2+B and the wth SOC value and the w+1th SOC value in the initial version of the discharge power table is equal, then h=w; When a<h, at T m , SOC h The corresponding discharge power and T m , and the discharge power corresponding to SOC1 are linearly interpolated to obtain T m , SOC a The corresponding discharge power is entered into the initial version of the discharge power table T m , SOC a The corresponding discharge power grid; where a takes all integers from h-1 to 2 in sequence; In the fourth step, the method of correcting the battery characteristics of the second version of the discharge power meter is: At the mth 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 is greater than T m , SOC v+1 The corresponding discharge power is T m , SOC v-1 The corresponding discharge power and T m , SOC v+1 The corresponding average value of discharge power is filled in the second version of the discharge power table T m , SOC v 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 The corresponding discharge power is greater than T d-1 , SOC p The corresponding discharge power is greater than T d+1 , SOC p The corresponding discharge power is T d-1 , SOC p The corresponding discharge power and T d+1 , SOC p The corresponding average value of discharge power is filled in the second version of the discharge power table T d , SOC p The corresponding discharge power grid; wherein p takes all integers from 1 to r in sequence, d is an integer and 2≤d≤n-1.

6. The method for controlling the discharge power of a power battery according to claim 2, characterized in that: If any of the conditions 1 to 3 is met, it means that the power battery stops discharging; Condition 1: The real-time SOC value of the power battery during discharge is 0%; Condition 2: Real-time minimum cell temperature T' of the power battery during discharge min <T th1 , or the real-time maximum cell temperature T' of the power battery max >T th2 ; Condition 3: Real-time minimum cell voltage U' of the power battery during discharge min ≤U' cut .

7. The method for controlling the discharge power of a power battery according to any one of claims 1 to 6, characterized in that: If T min In a preset temperature range, and U min If the temperature is greater than the preset undervoltage threshold corresponding to the preset temperature range, it is determined that the undervoltage is not triggered; If T min In a preset temperature range, and U min If the temperature is less than or equal to a preset undervoltage threshold corresponding to the preset temperature range, it is determined that undervoltage is triggered.

8. The method for controlling the discharge power of a power battery according to claim 7, characterized in that: The undervoltage power limiting strategy is: If T min In a preset temperature range, and U min is greater than the preset discharge cut-off voltage corresponding to the preset temperature range, and U min If the value is less than or equal to the preset undervoltage threshold value corresponding to the preset temperature range, the discharge power of the power battery is A*P; wherein A represents the preset undervoltage limit power coefficient; If T min In a preset temperature range, and U min If the temperature is less than or equal to the preset discharge cut-off voltage corresponding to the preset temperature range, the discharge power of the power battery is set to 0.

9. A discharge power control system for a power battery, comprising a controller, characterized in that: The controller is configured to execute the discharge power control method of the power battery as claimed in any one of claims 1 to 8.

10. A vehicle, characterized in that: A discharge power control system for a power battery comprising the method according to claim 9.

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