SOC (State of Charge) estimation method and system of power battery and vehicle

Abstract

The invention discloses an SOC estimation method and system for a power battery and a vehicle, and the method comprises the steps: determining a current compensation coefficient mu according to the current state of the vehicle when the vehicle is in a parking condition; taking the product of the current compensation coefficient mu and the current charging and discharging current I as an actual current calculation value; and carrying out ampere-hour integration by using the actual current calculation value, and estimating to obtain the SOC value of the power battery. By adopting the method, the SOC estimation error during low-current discharging under the parking working condition can be reduced, the SOC estimation accuracy is improved, the problem that the end of the charging time is relatively long due to the fact that the SOC estimation error is too large during subsequent charging is avoided, and the complaint of a user on the charging time is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of power battery management for vehicles, and particularly relates to a method and system for estimating the state of charge (SOC) of a power battery and a vehicle. Background Art

[0002] Currently, the SOC of the power batteries of most vehicles is estimated by the ampere-hour integration method. The ampere-hour integration method requires knowing the current charge and discharge current I of the power battery. Usually, a current sensor or a Hall sensor is used as the current sampling device to obtain the current charge and discharge current I of the power battery. Under driving conditions, generally the discharge current is large, and the current charge and discharge current I can be directly used for ampere-hour integration to estimate the SOC value of the power battery. However, under parking conditions, the discharge current of the vehicle is small (generally 0.3 A to 1.5 A), and the current sampling device has a certain sampling accuracy (for example, less than or equal to 0.3 A). At this time, if the current charge and discharge current I (for example, 1 A) is directly used for ampere-hour integration to estimate the SOC value of the power battery, the SOC estimation error will be as large as 30%, and as the integration time becomes longer, the SOC estimation error of the power battery will continue to accumulate. Under the condition of long-term small-current discharge, the cumulative proportion of the SOC estimation error is large. If the power battery is charged later, it will cause a longer end time of the charging time (that is, the user has a longer waiting time at the end of the charging to be fully charged), which is likely to cause user complaints. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and system for estimating the SOC of a power battery and a vehicle to improve the accuracy of SOC estimation of the power battery under parking conditions.

[0004] In a first aspect, the present invention provides a method for estimating the SOC of a power battery, which includes:

[0005] When the vehicle is in a parking condition, determining a current compensation coefficient μ according to the current vehicle state.

[0006] Taking μ*I as the actual current calculation value; where I represents the current charge and discharge current. That is, the product of the current compensation coefficient μ and the current charge and discharge current I is taken as the actual current calculation value.

[0007] Using the actual current calculation value for ampere-hour integration to estimate the SOC value of the power battery.

[0008] Preferably, the current vehicle state includes a high-voltage static state, a display vehicle mode, an intelligent charging mode, and a sentry mode.

[0009] If the current vehicle state is a high-voltage static state, the current compensation coefficient μ = k 1 ; if the current vehicle state is a display vehicle mode, the current compensation coefficient μ = k 2; If the current vehicle state is the intelligent charge compensation mode, then make the current compensation coefficient μ = k 3 ; If the current vehicle state is the sentry mode, then make the current compensation coefficient μ = k 4 . Wherein, k 1 represents the first preset current compensation coefficient value, k 2 represents the second preset current compensation coefficient value, k 3 represents the third preset current compensation coefficient value, k 4 represents the fourth preset current compensation coefficient value.

[0010] In the high-voltage static state, display vehicle mode, intelligent charge compensation mode (the power battery discharges to charge the battery), and sentry mode, the discharge current of the power battery is small. Therefore, it is necessary to compensate the current to reduce the SOC estimation error.

[0011] Preferably, the first preset current compensation coefficient value k 1 is obtained through the following steps:

[0012] S11. Make a sample vehicle with the SOC of the power battery being 100% (that is, the power battery of this sample vehicle is fully charged) in the high-voltage static state, and discharge the power battery of this sample vehicle (the initial SOC is 100%) at a constant current with the first preset current I 11 for a preset time t 1 , record the SOC value X 1 of the power battery of this sample vehicle after the discharge ends, and then execute S12.

[0013] S12. Plug in and fully charge the power battery of this sample vehicle (the initial SOC is X 1 ) according to the charging rate of the charging gun (that is, charge it until the SOC reaches 100%), record the charging time t 11 , and calculate the first actual charging capacity Q 11 , and then execute S13.

[0014] S13. Use the formula: Q 10 = (100% - X 1 ) * Q e , calculate the first theoretical charging capacity Q 10 , and then execute S14; wherein, Q e represents the rated capacity of the power battery.

[0015] S14. Use the formula: △Q 1 = |Q 11 - Q 10 |, calculate the first capacity error △Q 1 , and then execute S15.

[0016] S15. Calculate the preset time t 1Consume the first capacity error ΔQ completely 1 The required current I 12 , and then execute S16.

[0017] S16. Using the formula: k 11 = 1 + I 12 / I 11 , calculate a first current compensation coefficient value k 11 , and then execute S17.

[0018] S17. Repeat S11 to S16 n times to obtain a total of n + 1 first current compensation coefficient values k 11 , and then execute S18.

[0019] S18. Take the average value of the n + 1 first current compensation coefficient values k 11 as the first preset current compensation coefficient value k 1 , and then end.

[0020] When the vehicle discharges with a small current under the high - voltage static state (i.e., the consumed current is small), it is greatly affected by the acquisition accuracy of the current sampling device. If it is in the high - voltage static state for a long time, the SOC estimation error will become larger and larger. Therefore, it is necessary to use the above method to obtain the first preset current compensation coefficient value k 1 to compensate the current and reduce the SOC estimation error under the high - voltage static state. During the test, first perform a constant - current discharge with a first preset current I 1 for a preset time t 11 (i.e., a small - current constant - current discharge), then charge it fully, use the difference between the first actual charging capacity and the first theoretical charging capacity as the first capacity error, and then calculate the current I 1 required to consume the first capacity error within the preset time t 12 . Add the ratio of this current I 12 to the current I 11 of the aforementioned constant - current discharge and add the base coefficient 1 to obtain the first current compensation coefficient value k 11 . Then take the average value of n + 1 first current compensation coefficient values k 11 as k 1 , thus ensuring the rationality and accuracy of the calculation of k 1 .

[0021] Preferably, the second preset current compensation coefficient value k 2 is obtained through the following steps:

[0022] S21. Make a sample vehicle with the SOC of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the display vehicle mode, and discharge the power battery of this sample vehicle (the initial SOC is 100%) with a second preset current I 21The preset time t for constant current discharge 1 , record the SOC value X of the power battery of the sample vehicle after the discharge ends 2 , and then execute S22.

[0023] S22. Plug in and fully charge the power battery of the sample vehicle (with the starting SOC being X 2 ) at the charging rate of the charging gun (i.e., charge until the SOC value reaches 100%), record the charging time t 21 , and calculate the second actual charging capacity Q 21 , and then execute S23.

[0024] S23. Use the formula: Q 20 =(100%-X 2 )*Q e , calculate the second theoretical charging capacity Q 20 , and then execute S24.

[0025] S24. Use the formula: △Q 2 =|Q 21 -Q 20 |, calculate the second capacity error △Q 2 , and then execute S25;

[0026] S25. Calculate the current I required to consume the second capacity error △Q within the preset time t 1 2 , and then execute S26. 22

[0027] S26. Use the formula: k 21 =1+I 22 / I 21 , calculate a second current compensation coefficient value k 21 , and then execute S27.

[0028] S27. Repeat S21 to S26 n times, and a total of n + 1 second current compensation coefficient values k are obtained 21 , and then execute S28.

[0029] S28. Take the average value of the n + 1 second current compensation coefficient values k as the second preset current compensation coefficient value k 21 2 , and then end.

[0030] In the display vehicle mode, the vehicle discharges at a small current (i.e., consumes a small current), which is greatly affected by the acquisition accuracy of the current sampling device. If it is in the display vehicle mode for a long time, the SOC estimation error will become larger and larger. Therefore, it is necessary to use the above method to obtain the second preset current compensation coefficient value k 2 ​​​, to compensate for the current and reduce the SOC estimation error in the exhibition vehicle mode. During the test, first perform a preset time t 1 of the second preset current I 21 constant current discharge (i.e., small current constant current discharge), then fully charge, use the difference between the second actual charge capacity and the second theoretical charge capacity as the second capacity error, and then calculate the preset time t 1 required to consume the second capacity error within the current I 22 , and use this current I 22 and the current I 21 of the aforementioned constant current discharge 21 to obtain the second current compensation coefficient value k 21 by adding the ratio of the two to the base coefficient 1, and then take the average value of n + 1 second current compensation coefficient values k 2 as k 2 , thus ensuring the rationality and accuracy of the calculation of k

[0031] Preferably, the third preset current compensation coefficient value k 3 is obtained through the following steps:

[0032] S31. Make a sample vehicle with the SOC of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the intelligent charging compensation mode, and discharge the power battery of this sample vehicle (starting SOC is 100%) at a third preset current I 31 for a preset time t 1 , record the SOC value X 3 of the power battery of this sample vehicle after the discharge ends, and then execute S32.

[0033] S32. Plug in and fully charge the power battery of this sample vehicle (starting SOC is X 3 ) according to the charging rate of the charging gun (i.e., charge until the SOC value reaches 100%), record the charging time t 31 , and calculate the third actual charge capacity Q 31 , and then execute S33.

[0034] S33. Use the formula: Q 30 =(100% - X 3 )*Q e to calculate the third theoretical charge capacity Q 30 , and then execute S34.

[0035] S34. Use the formula: △Q 3 =|Q 31 -Q 30 | to calculate the third capacity error △Q 3 , and then execute S35.

[0036] S35. Calculate the preset time t1 Consume the third capacity error ΔQ within 3 The required current I 32 , and then execute S36.

[0037] S36. Use the formula: k 31 = 1 + I 32 / I 31 , calculate to obtain a third current compensation coefficient value k 31 , and then execute S37.

[0038] S37. Repeat S31 to S36 n times to obtain a total of n + 1 third current compensation coefficient values k 31 , and then execute S38.

[0039] S38. Take the average value of the n + 1 third current compensation coefficient values k 31 as the third preset current compensation coefficient value k 3 , and then end.

[0040] In the intelligent charge compensation mode, the vehicle discharges with a small current (i.e., the consumed current is small), which is greatly affected by the acquisition accuracy of the current sampling device. If it is in the intelligent charge compensation mode for a long time, the SOC estimation error will become larger and larger. Therefore, the above method is needed to obtain the third preset current compensation coefficient value k 3 , to compensate the current and reduce the SOC estimation error in the intelligent charge compensation mode. During the test, first perform a constant current discharge with the third preset current I 1 for a preset time t 31 (i.e., a small constant current discharge), then fully charge the battery. Use the difference between the third actual charging capacity and the third theoretical charging capacity as the third capacity error, and then calculate the current I 1 required to consume the third capacity error within the preset time t 32 . Add the ratio of this current I 32 to the current I 31 of the aforementioned constant current discharge and add the base coefficient 1 to obtain the third current compensation coefficient value k 31 . Then take the average value of n + 1 third current compensation coefficient values k 31 as k 3 , thus ensuring the rationality and accuracy of the calculation of k 3 .

[0041] Preferably, the fourth preset current compensation coefficient value k 4 is obtained through the following steps:

[0042] S41. Make a sample vehicle with the SOC of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the sentry mode, and discharge the power battery of this sample vehicle (starting SOC is 100%) with the fourth preset current I41 The preset time t for constant current discharge 1 , record the SOC value X of the power battery of the sample vehicle after the discharge ends 4 , and then execute S42

[0043] S42. Insert the charging gun of the sample vehicle's power battery (starting SOC is X 4 ) and charge it to full at the charging rate of the charging gun (that is, charge until the SOC value reaches 100%), record the charging time t 41 , and calculate the fourth actual charging capacity Q 41 , and then execute S43

[0044] S43. Use the formula: Q 40 =(100%-X 4 )*Q e , calculate the fourth theoretical charging capacity Q 40 , and then execute S44

[0045] S44. Use the formula: △Q 4 =|Q 41 -Q 40 |, calculate the fourth capacity error △Q 4 , and then execute S45

[0046] S45. Calculate the current I required to consume the fourth capacity error △Q within the preset time t 1 4 , and then execute S46 42

[0047] S46. Use the formula: k 41 =1+I 42 / I 41 , calculate a fourth current compensation coefficient value k 41 , and then execute S47

[0048] S47. Repeat S41 to S46 n times, and a total of n + 1 fourth current compensation coefficient values k are obtained 41 , and then execute S48

[0049] S48. Take the average value of the n + 1 fourth current compensation coefficient values k 41 as the fourth preset current compensation coefficient value k 4 , and then end

[0050] When the vehicle discharges with a small current in the sentry mode (that is, the consumed current is small), it is greatly affected by the acquisition accuracy of the current sampling device. If it is in the sentry mode for a long time, the SOC estimation error will become larger and larger. Therefore, the above method is needed to obtain the fourth preset current compensation coefficient value k 4 ​​, to compensate for the current and reduce the SOC estimation error in the sentinel mode. During the test, first perform a preset time t 1 of the fourth preset current I 41 constant current discharge (i.e., small current constant current discharge), then fully charge, use the difference between the fourth actual charge capacity and the fourth theoretical charge capacity as the fourth capacity error, and then calculate the preset time t 1 the current I required to consume the fourth capacity error within 42 , and this current I 42 is added to the current I of the aforementioned constant current discharge 41 and the ratio plus the base coefficient 1 to obtain the fourth current compensation coefficient value k 41 , and then take the average value of n + 1 fourth current compensation coefficient values k 41 as k 4 , thus ensuring the calculation rationality and accuracy of k 4 .

[0051] Preferably, the preset time t 1 = 48h (i.e., 48 hours).

[0052] Preferably, the value range of n is an integer from 3 to 10.

[0053] In a second aspect, the present invention provides an SOC estimation system for a power battery, which includes a controller programmed to execute the above SOC estimation method for the power battery.

[0054] In a third aspect, the present invention provides a vehicle, which includes the above SOC estimation system for the power battery.

[0055] Under the parking condition, compensate the current charge and discharge current according to the current vehicle state, and perform ampere-hour integration using the compensated actual current calculation value, thereby reducing the SOC estimation error during small current discharge under the parking condition, improving the SOC estimation accuracy of the power battery under the parking condition, avoiding the problem of a long charging time at the end due to excessive SOC estimation error during subsequent charging, and avoiding user complaints about the charging time. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a flowchart of the SOC estimation method for the power battery in the embodiment of the present invention.

[0057] Figure 2 is a flowchart of the method for obtaining the first preset current compensation coefficient value k 1 in the embodiment of the present invention.

[0058] Figure 3 is a flowchart of the method for obtaining the second preset current compensation coefficient value k 2 in the embodiment of the present invention.

[0059] Figure 4 For obtaining the third preset current compensation coefficient value k in the embodiments of the present invention 3 is the flowchart of the method.

[0060] Figure 5 For obtaining the fourth preset current compensation coefficient value k in the embodiments of the present invention 4 is the flowchart of the method. Detailed implementation manners

[0061] In order to understand the features and technical content of the embodiments of the present invention in more detail, 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 only for reference and explanation, and are not used to limit the embodiments of the present invention.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field 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.

[0063] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0064] As Figure 1 shown, the SOC estimation method of the power battery in the embodiments of the present invention is executed by a controller, and includes:

[0065] First step, determine whether the vehicle is in a parking condition. If so, execute the third step; otherwise (that is, when the vehicle is in a driving condition), execute the second step. Among them, the method of determining whether the vehicle is in a parking condition or a driving condition belongs to the prior art.

[0066] Second step, perform ampere-hour integration using the current charge and discharge current I to estimate the SOC value of the power battery, and then return to execute the first step. The ampere-hour integration formula is: represents the current SOC of the power battery, SOC(0) represents the initial (starting) SOC of the power battery, Q e represents the rated capacity of the power battery, η represents the charge and discharge efficiency, Q e , η are known quantities, I represents the current charge and discharge current (also the charge and discharge current at time t), and I is collected by a current sampling device.

[0067] Third step, determine whether the current vehicle state is a high-voltage static state. If so, execute the fourth step; otherwise, execute the fifth step.

[0068] In some embodiments, the controller may determine the current vehicle state based on the status flag bits. For example: when the status flag bit is 1000, it indicates that the current vehicle state is the high-voltage static state; when the status flag bit is 0100, it indicates that the current vehicle state is the display vehicle mode; when the status flag bit is 0010, it indicates that the current vehicle state is the intelligent charge compensation mode; when the status flag bit is 0001, it indicates that the current vehicle state is the sentry mode; when the status flag bit is 0000, it indicates that the current vehicle state is other modes except the high-voltage static state, the display vehicle mode, the intelligent charge compensation mode, and the sentry mode. Other modes are not discussed in this embodiment.

[0069] Step 4: Set the current compensation coefficient μ = k 1 , and then execute Step 11. Here, k 1 represents the first preset current compensation coefficient value.

[0070] In some embodiments, the first preset current compensation coefficient value k 1 is obtained through the following steps (see Figure 2 ):

[0071] S11: Place a sample vehicle with the state of charge (SOC) of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the high-voltage static state, and discharge the power battery of this sample vehicle (starting SOC is 100%) at a constant current with the first preset current I 11 for a preset time t 1 , and record the SOC value X 1 of the power battery of this sample vehicle after the discharge ends, and then execute S12.

[0072] The SOC value X 1 of the power battery of this sample vehicle after the discharge ends is obtained by using the ampere-hour integration estimation with the first preset current I 11 for the preset time t 1 . As an example, the first preset current I 11 = 0.5 A, and the preset time t 1 = 48 h (i.e., 48 hours).

[0073] The current compensation coefficient μ is not affected by temperature. Therefore, temperature is not considered in this discharge test and the subsequent charge test, and both are carried out at room temperature.

[0074] S12: Plug in and fully charge the power battery of this sample vehicle (starting SOC is X 1 ) according to the charging rate of the charging gun (i.e., charge until the SOC reaches 100%), record the charging time t 11 , and calculate the first actual charging capacity Q 11 , and then execute S13. Here, based on the charging time t 11 , the charging rate C of the charging gun, and the rated capacity Q of the power batterye , calculate the first actual charging capacity Q 11 , the formula is: C * Q e represents the charging current of the charging gun, and C is a known quantity.

[0075] S13. Use the formula: Q 10 = (100% - X 1 ) * Q e , calculate the first theoretical charging capacity Q 10 , and then execute S14.

[0076] S14. Use the formula: △Q 1 = |Q 11 - Q 10 |, calculate the first capacity error △Q 1 , and then execute S15.

[0077] S15. Calculate the preset time t 1 within which △Q is consumed 1 required current I 12 , and then execute S16. Specifically, use the equation: to solve for I 12 .

[0078] S16. Use the formula: k 11 = 1 + I 12 / I 11 , calculate a first current compensation coefficient value k 11 , and then execute S17.

[0079] S17. Repeat S11 to S16 n times, and a total of n + 1 first current compensation coefficient values k 11 are obtained, and then execute S18.

[0080] In some embodiments, the value range of n is an integer from 3 to 10. As an example, n = 8.

[0081] During the test, use a sample vehicle to perform 9 times of the above-mentioned discharge and charging tests to obtain 9 first current compensation coefficient values k 11 . In some embodiments, it is also possible to use 3 identical sample vehicles to perform 3 times of the above-mentioned discharge and charging tests simultaneously to obtain 9 first current compensation coefficient values k 11 .

[0082] S18. Take the average value of the n + 1 first current compensation coefficient values k 11 as the first preset current compensation coefficient value k 1 , and then end.

[0083] Step 5: Determine whether the current vehicle state is the display vehicle mode. If it is, execute Step 6; otherwise, execute Step 7.

[0084] Step 6: Set the current compensation coefficient μ = k 2 , and then execute Step 11. Here, k 2 represents the second preset current compensation coefficient value.

[0085] In some embodiments, the second preset current compensation coefficient value k 2 is obtained through the following steps (see Figure 3 ):

[0086] S21: Put a sample vehicle with the state of charge (SOC) of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the display vehicle mode. Discharge the power battery of this sample vehicle (starting SOC is 100%) at a constant current with the second preset current I 21 for a preset time t 1 , record the SOC value X 2 of the power battery of this sample vehicle after the discharge ends, and then execute S22.

[0087] The SOC value X 2 of the power battery of this sample vehicle after the discharge ends is obtained by estimating the ampere-hour integral with the second preset current I 21 for a preset time t 1 . As an example, the second preset current I 21 = 0.7 A.

[0088] S22: Plug in the charging gun of this sample vehicle to fully charge the power battery (starting SOC is X 2 ) at the charging rate of the charging gun (i.e., charge until the SOC value reaches 100%), record the charging time t 21 , and calculate the second actual charging capacity Q 21 , and then execute S23. Here, based on the charging time t 21 , the charging rate C of the charging gun, and the rated capacity Q e of the power battery, calculate the second actual charging capacity Q 21 , and the formula is:

[0089] S23: Use the formula: Q 20 = (100% - X 2 ) * Q e to calculate the second theoretical charging capacity Q 20 , and then execute S24.

[0090] S24: Use the formula: △Q 2 = |Q 21 - Q 20 | to calculate the second capacity error △Q2 , then execute S25.

[0091] S25. Calculate the preset time t 1 required to consume ΔQ within 2 the current I 22 , then execute S26. Specifically, use the equation: to solve for I 22 .

[0092] S26. Use the formula: k 21 = 1 + I 22 / I 21 to calculate a second current compensation coefficient value k 21 , then execute S27.

[0093] S27. Repeat S21 to S26 n times to obtain a total of n + 1 second current compensation coefficient values k 21 , then execute S28.

[0094] S28. Take the average of the n + 1 second current compensation coefficient values k 21 as the second preset current compensation coefficient value k 2 , then end.

[0095] Seventh step. Determine whether the current vehicle state is the intelligent charge compensation mode. If so, execute the eighth step; otherwise, execute the ninth step.

[0096] Eighth step. Set the current compensation coefficient μ = k 3 , then execute the eleventh step. Here, k 3 represents the third preset current compensation coefficient value.

[0097] In some embodiments, the third preset current compensation coefficient value k 3 is obtained through the following steps (see Figure 4 ):

[0098] S31. Place a sample vehicle with the SOC of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the intelligent charge compensation mode, and discharge the power battery of this sample vehicle (starting SOC is 100%) at a constant current with the third preset current I 31 for a preset time t 1 , record the SOC value X of the power battery of this sample vehicle after the discharge ends 3 , then execute S32.

[0099] The SOC value X of the power battery of this sample vehicle after the discharge ends 3 by using the third preset current I 31 for a preset time t 1Obtained by ampere-hour integration. As an example, the third preset current I 31 = 1.5 A.

[0100] S32. Plug the charging gun of the prototype vehicle's power battery (starting SOC is X 3 ) at the charging rate of the charging gun until it is fully charged (i.e., until the SOC value reaches 100%), record the charging time t 31 , and calculate the third actual charging capacity Q 31 . Then execute S33. Here, based on the charging time t 31 , the charging rate C of the charging gun, and the rated capacity Q e of the power battery, calculate the third actual charging capacity Q 31 . The formula is:

[0101] S33. Use the formula: Q 30 =(100% - X 3 ) * Q e , calculate the third theoretical charging capacity Q 30 . Then execute S34.

[0102] S34. Use the formula: △Q 3 = |Q 31 - Q 30 |, calculate the third capacity error △Q 3 . Then execute S35.

[0103] S35. Calculate the current I 1 required to consume △Q 3 within the preset time t 32 . Then execute S36. Specifically, use the equation: to solve for I 32 .

[0104] S36. Use the formula: k 31 = 1 + I 32 / I 31 , calculate a third current compensation coefficient value k 31 . Then execute S37.

[0105] S37. Repeat S31 to S36 n times to obtain a total of n + 1 third current compensation coefficient values k 31 . Then execute S38.

[0106] S38. Take the average of the n + 1 third current compensation coefficient values k 31 as the third preset current compensation coefficient value k 3 . Then end.

[0107] Step 9: Determine whether the current vehicle state is the sentry mode. If so, execute Step 10; otherwise, return to execute Step 1.

[0108] Step 10: Set the current compensation coefficient μ = k 4 , and then execute Step 11. Here, k 4 represents the fourth preset current compensation coefficient value.

[0109] In some embodiments, the fourth preset current compensation coefficient value k 4 is obtained through the following steps (see Figure 5 ):

[0110] S41: Put a sample vehicle with the state of charge (SOC) of the power battery being 100% (i.e., the power battery of this sample vehicle is fully charged) in the sentry mode. Discharge the power battery of this sample vehicle (starting SOC is 100%) at a constant current with the fourth preset current I 41 for a preset time t 1 , and record the SOC value X 4 of the power battery of this sample vehicle after the discharge ends, and then execute S42.

[0111] The SOC value X 4 of the power battery of this sample vehicle after the discharge ends is obtained by estimating the ampere-hour integral with the fourth preset current I 41 for a preset time t 1 . As an example, the fourth preset current I 41 = 0.9 A.

[0112] S42: Plug in the charging gun of this sample vehicle to fully charge the power battery (starting SOC is X 4 ) at the charging rate of the charging gun (i.e., charge until the SOC value reaches 100%), record the charging time t 41 , and calculate the fourth actual charging capacity Q 41 , and then execute S43. Here, based on the charging time t 41 , the charging rate C of the charging gun, and the rated capacity Q e of the power battery, calculate the fourth actual charging capacity Q 41 , and the formula is:

[0113] S43: Use the formula: Q 40 = (100% - X 4 ) * Q e to calculate the fourth theoretical charging capacity Q 40 , and then execute S44.

[0114] S44: Use the formula: ΔQ 4 = |Q 41 - Q 40 | to calculate the fourth capacity error ΔQ4 , then execute S45.

[0115] S45. Calculate the preset time t 1 to consume △Q completely 4 the required current I 42 , then execute S46. Specifically, use the equation: to solve for I 42 .

[0116] S46. Use the formula: k 41 = 1 + I 42 / I 41 to calculate a fourth current compensation coefficient value k 41 , then execute S47.

[0117] S47. Repeat S41 to S46 n times to obtain a total of n + 1 fourth current compensation coefficient values k 41 , then execute S48.

[0118] S48. Take the average value of the n + 1 fourth current compensation coefficient values k 41 as the fourth preset current compensation coefficient value k 4 , then end.

[0119] The eleventh step: Take μ * I (i.e., the product of the current compensation coefficient μ and the current charge and discharge current I) as the actual current calculation value, then execute the twelfth step.

[0120] The twelfth step: Perform ampere-hour integration using the actual current calculation value to estimate the SOC value of the power battery, then return to execute the first step. The formula for performing ampere-hour integration using the actual current calculation value to estimate the SOC value of the power battery is:

[0121]

[0122] The estimated SOC value of the power battery can be sent to the instrument for the user to observe.

[0123] In addition, an embodiment of the present invention further provides a SOC estimation system for a power battery, which includes a controller programmed to execute the above SOC estimation method for the power battery. In some embodiments, the controller here may be the controller of the BMS.

[0124] In addition, an embodiment of the present invention further provides a vehicle, which includes the above SOC estimation system for the power battery.

[0125] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art 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 estimating the SOC of a power battery, characterized in that: include: When the vehicle is in a parking condition, the current compensation coefficient μ is determined according to the current vehicle state; μ*I is used as the actual current calculation value; where I represents the current charge and discharge current; The actual current calculation value is used to perform ampere-hour integration to estimate the SOC value of the power battery.

2. The SOC estimation method of a power battery according to claim 1, characterized in that: The current vehicle state includes a high-voltage static state, a display vehicle mode, an intelligent charging mode, and a sentinel mode; If the current vehicle state is a high-voltage static state, the current compensation coefficient μ=k1; If the current vehicle state is the exhibition vehicle mode, the current compensation coefficient μ=k2; If the current vehicle state is in the intelligent charging mode, the current compensation coefficient μ=k3; If the current vehicle state is sentinel mode, the current compensation coefficient μ=k4; Among them, k1 represents the first preset current compensation coefficient value, k2 represents the second preset current compensation coefficient value, k3 represents the third preset current compensation coefficient value, and k4 represents the fourth preset current compensation coefficient value.

3. The SOC estimation method of a power battery according to claim 2, characterized in that: The first preset current compensation coefficient value k1 is obtained by the following steps: S11, placing the prototype vehicle with the power battery SOC of 100% in a high-voltage static state, and charging the power battery of the prototype vehicle at a first preset current I 11 The constant current discharge is preset for a time t1, and the SOC value X1 of the power battery of the sample vehicle after the discharge is completed is recorded, and then S12 is executed; S12, plug the power battery of the sample vehicle into the charging gun and charge it to full capacity according to the charging rate of the charging gun, and record the charging time t 11 , and calculate the first actual charging capacity Q 11 , then execute S13; S13, using the formula: Q 10 =(100%- X1)*Q e , calculate the first theoretical charge capacity Q 10 , then execute S14; where Q e Indicates the rated capacity of the power battery; S14, using the formula: △Q1=|Q 11 -Q 10 |, calculate the first capacity error △Q1, and then execute S15; S15, calculate the current I required to consume △Q1 within the preset time t1 12 , then execute S16; S16, using the formula: k 11 =1+ I 12 / I 11 , calculate and obtain a first current compensation coefficient value k 11 , then execute S17; S17, repeat S11 to S16 n times, and obtain a total of n+1 first current compensation coefficient values ​​k 11 , then execute S18; S18, set n+1 first current compensation coefficient values ​​k 11 The average value of is used as the first preset current compensation coefficient value k1, and then the process ends.

4. The SOC estimation method of a power battery according to claim 2, characterized in that: The second preset current compensation coefficient value k2 is obtained by the following steps: S21, placing the prototype vehicle whose power battery SOC is 100% in the exhibition vehicle mode, and charging the power battery of the prototype vehicle at a second preset current I 21 The constant current discharge is preset for a time t1, and the SOC value X2 of the power battery of the sample vehicle after the discharge is completed is recorded, and then S22 is executed; S22, charge the power battery of the sample vehicle to full capacity according to the charging rate of the charging gun, and record the charging time t 21 , and calculate the second actual charging capacity Q 21 , then execute S23; S23, using the formula: Q 20 =(100%- X2)*Q e , calculate the second theoretical charging capacity Q 20 , then execute S24; wherein, Q e Indicates the rated capacity of the power battery; S24. Use the formula: △Q2=|Q 21 -Q 20 |, calculate the second capacity error △Q2, and then execute S25; S25, calculate the current I required to consume △Q2 within the preset time t1 22 , then execute S26; S26, using the formula: k 21 =1+ I 22 / I 21 , calculate and obtain a second current compensation coefficient value k 21 , then execute S27; S27, repeat S21 to S26 n times, and obtain a total of n+1 second current compensation coefficient values ​​k 21 , then execute S28; S28, set n+1 second current compensation coefficient values ​​k 21 The average value of is used as the second preset current compensation coefficient value k2, and then the process ends.

5. The SOC estimation method of a power battery according to claim 2, characterized in that: The third preset current compensation coefficient value k3 is obtained by the following steps: S31, placing the prototype vehicle whose power battery SOC is 100% in the intelligent charging mode, and charging the power battery of the prototype vehicle at a third preset current I 31 The constant current discharge is preset for a time t1, and the SOC value X3 of the power battery of the sample vehicle after the discharge is completed is recorded, and then S32 is executed; S32, fully charge the power battery of the sample vehicle according to the charging rate of the charging gun, and record the charging time t 31 , and calculate the third actual charging capacity Q 31 , then execute S33; S33. Use formula: Q 30 =(100%- X3)*Q e , calculate the third theoretical charging capacity Q 30 , then execute S34; wherein, Q e Indicates the rated capacity of the power battery; S34. Use the formula: △Q3=|Q 31 -Q 30 |, calculate the third capacity error △Q3, and then execute S35; S35, calculate the current I required to consume △Q3 within the preset time t1 32 , then execute S36; S36, using the formula: k 31 =1+ I 32 / I 31 , calculate and obtain a third current compensation coefficient value k 31 , then execute S37; S37, repeat S31 to S36 n times, and obtain a total of n+1 third current compensation coefficient values ​​k 31 , then execute S38; S38, set n+1 third current compensation coefficient values ​​k 31 The average value of is used as the third preset current compensation coefficient value k3, and then the process ends.

6. The SOC estimation method of a power battery according to claim 2, characterized in that: The fourth preset current compensation coefficient value k4 is obtained by the following steps: S41, placing the prototype vehicle whose power battery SOC is 100% in sentinel mode, and charging the power battery of the prototype vehicle at a fourth preset current I 41 The constant current discharge is preset for a time t1, and the SOC value X4 of the power battery of the sample vehicle after the discharge is completed is recorded, and then S42 is executed; S42, fully charge the power battery of the sample vehicle according to the charging rate of the charging gun, and record the charging time t 41 , and calculate the fourth actual charging capacity Q 41 , then execute S43; S43. Use formula: Q 40 =(100%- X4)*Q e , calculate the fourth theoretical charging capacity Q 40 , then execute S44; wherein, Q e Indicates the rated capacity of the power battery; S44. Use the formula: △Q4=|Q 41 -Q 40 |, calculate the fourth capacity error △Q4, and then execute S45; S45, calculate the current I required to consume △Q4 within the preset time t1 42 , then execute S46; S46, using the formula: k 41 =1+ I 42 / I 41 , calculate and obtain a fourth current compensation coefficient value k 41 , then execute S47; S47, repeat S41 to S46 n times, and obtain a total of n+1 fourth current compensation coefficient values ​​k 41 , then execute S48; S48, set n+1 fourth current compensation coefficient values ​​k 41 The average value of is used as the fourth preset current compensation coefficient value k4, and then ends.

7. The SOC estimation method of a power battery according to any one of claims 3 to 6, characterized in that: The preset time t1=48h.

8. The method for estimating the SOC of a power battery according to any one of claims 3 to 6, characterized in that: The value of n is an integer ranging from 3 to 10.

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

10. A vehicle, characterized in that: A SOC estimation system for a power battery comprising the system as claimed in claim 9.

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