Method for correcting SOC (state of charge) under frequent uphill and downhill working conditions

Abstract

The invention discloses a frequent uphill and downhill working condition SOC correction method, which combines charge and discharge dynamic calibration and full charge calibration to realize accurate correction of the SOC of a power battery. The method comprises the following steps: calculating a display SOC value at a current temperature according to an SOC capacity hidden value and an algorithm estimation value; for the long uphill road section, according to the current multiplying power, the minimum single voltage, the display SOC value and the difference value of the target discharge correction value, dynamic discharge calibration is executed; for a long downhill road section, feedback charging is carried out on the battery, charging dynamic calibration is not carried out in feedback charging, and the SOC is limited to be equal to or lower than an SOC full charge waiting value; when the battery is insufficient in power and needs to be charged, dynamic charging calibration is executed according to the current multiplying power, the highest single voltage, the target charging correction value and the display SOC value; and when the battery is in a charging state, the maximum monomer voltage is greater than or equal to the full-charging cut-off voltage for the full-charging duration, and the absolute value of the charging current is less than or equal to the overcurrent alarm value, performing full-charging calibration on the battery.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a SOC correction method for frequent uphill and downhill conditions. Background Art

[0002] Frequent uphill and downhill conditions refer to the situation where the vehicle has continuous long uphill and downhill conditions during driving. This is more common in mountainous and hilly areas in my country, and the golf courses where golf carts work are also such conditions. On long downhill sections, power battery vehicles do not even need to step on the accelerator, and can obtain greater acceleration by relying on inertia. When the vehicle brakes and feeds back when going downhill, the energy recovered by the kinetic energy recovery system charges the vehicle in reverse, and can even charge the vehicle almost fully when it is fed back in a high SOC (State of Charge) state. On long uphill sections, because climbing requires high power, the battery will discharge with a large current, and the SOC will drop significantly; frequent uphill and downhill conditions will cause the downhill feedback charging SOC value to be high, which will lead to inaccurate SOC. In low temperature environments such as winter, the battery cannot discharge the rated capacity due to the low temperature, which will also lead to inaccurate SOC calculation. Accurate calculation of SOC is related to the efficiency of power battery vehicles, which can prevent the vehicle from running out of power and improve the comfort of users.

[0003] Common SOC correction methods for frequent uphill and downhill conditions in engineering include the ampere-hour integration method and the open circuit voltage method. The ampere-hour integration method calculates the net capacity flowing into the battery by integrating the current over time, and calculates the SOC based on the net flow divided by the rated capacity. However, due to errors in current sampling, the SOC error will become larger and larger as time accumulates. The open circuit voltage method corrects the SOC based on the battery's OCV-SOC curve when the battery is powered on after it has been stationary for a period of time. However, the actual battery may have fewer opportunities to be stationary during use, and the open circuit voltage method cannot be performed during operation, resulting in the inability to correct the SOC in a timely manner. Summary of the invention

[0004] In order to make up for the shortcomings of the prior art, the present invention provides a SOC correction method for frequent uphill and downhill conditions, which adopts the SOC capacity hiding method based on temperature, combines the charge and discharge dynamic calibration and the full charge calibration, and realizes the accurate correction of the power battery SOC to solve the SOC inaccuracy problem caused by frequent feedback charging in frequent uphill and downhill conditions.

[0005] The technical problem solved by the present invention can be achieved through the following technical solutions:

[0006] The SOC correction method for frequent uphill and downhill conditions comprises the following steps:

[0007] S1. Obtain the hidden SOC capacity value SOC_Hide at different temperatures through temperature lookup table, and calculate the displayed SOC value SOC_Disp according to SOC_Hide and SOC_Pre estimated by the algorithm, that is, the SOC at the current temperature;

[0008] S2. For a long uphill section, a discharge dynamic calibration is performed according to the difference between the current multiple Crate_dis, the minimum cell voltage Vmin, the displayed SOC value SOC_Disp and the target discharge correction value SOCthr_Dis;

[0009] S3: For long downhill sections, the battery will be recharged. The recharged charging does not perform dynamic charging calibration, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT or below.

[0010] S4. When the battery is low on power and needs to be charged, a dynamic charging calibration is performed according to the difference between the current rate Crate_chg, the maximum cell voltage Vmax, the target charge correction value SOCthr_Chg and the displayed SOC value SOC_Disp;

[0011] S5. When the battery is in a charging state, the maximum single cell voltage Vmax ≥ the full charge cut-off voltage V_Fullchg for the full charge duration Fullchg_Time, and the charging current absolute value Cur_Chg ≤ the current overcurrent alarm value Cur_Over, the battery is fully charged and calibrated to 100% SOC.

[0012] Furthermore, the process of hiding the SOC capacity in step S1 is as follows:

[0013] S11. When the temperature is low, the rated capacity at room temperature cannot be discharged due to the characteristics of the battery cell. The lower the temperature, the more capacity cannot be discharged, and the corresponding SOC capacity hidden value SOC_Hide is larger;

[0014] S12, carrying out discharge capacity tests at different temperatures, obtaining a SOC capacity hidden value SOC_Hide table related to the temperature Temp, looking up the SOC_Hide table by temperature linear interpolation, and obtaining the SOC_Hide corresponding to the current temperature Temp;

[0015] S13. Calculate and display the SOC value SOC_Disp according to SOC_Hide and SOC_Pre estimated by the algorithm, that is, the SOC at the current temperature. The specific calculation formula is:

[0016]

[0017] Among them, SOC_Disp is the output displayed SOC value, SOC_Pre is the SOC value estimated by the algorithm, SOC_Hide is the SOC capacity hidden value, and the above SOCs are all calculated in %.

[0018] Furthermore, in the step S13, when the SOC_Pre estimated by the algorithm is ≤ the SOC capacity hidden value SOC_Hide, the displayed SOC value SOC_Disp is 0%; when the SOC_Pre estimated by the algorithm is ≥100%, the displayed SOC value SOC_Disp is 100%.

[0019] Furthermore, in step S2, the process of discharge dynamic calibration is as follows:

[0020] S21. For long uphill sections, the battery discharge current is large. The large current will rapidly reduce the single cell voltage. At this time, dynamic calibration is not suitable. The discharge end should be dynamically calibrated when the current is moderate, that is, the discharge current Cur_Dis should be greater than the current zero drift value CurDrift, and Cur_Dis should be less than the current multiple Crate_dis, where the current multiple Crate_dis is obtained by taking the quotient of the discharge current Cur_Dis and the battery rated capacity Q. When step S21 is satisfied, continue to step S22;

[0021] S22, when the temperature is low, calibration is performed based on the SOC capacity hidden value SOC_Hide, and when the lowest cell temperature Tmin> the temperature threshold T_MIN, discharge dynamic calibration is performed. When step S22 is satisfied, step S23 is continued;

[0022] S23, when steps S21 and S22 are satisfied, and the minimum cell voltage Vmin≤discharge voltage threshold V_MIN_Dis for a duration of more than Dur_Time, and the displayed SOC-target discharge correction value SOCthr_Dis≥discharge SOC difference SOC_Diff_Dis, perform discharge dynamic calibration;

[0023] S24: When step S21, S22 or S23 is not satisfied, the discharge dynamic calibration is not performed.

[0024] Furthermore, in step S23, when the target discharge correction value SOCthr_Dis>0%, the SOC is corrected to SOCthr_Dis+SOC_Diff_Dis at the correction rate Crt_rate1; when the target discharge correction value SOCthr_Dis=0%, that is, the battery power is about to be exhausted, the SOC is corrected to 0% at the correction rate Crt_rate2, where Crt_rate2>Crt_rate1.

[0025] Furthermore, in step S3, the regenerative charging is limited as follows: for long downhill sections, the battery will be regeneratively charged when the brakes are applied, and only ampere-hour integration is performed during regenerative charging, and no dynamic charging calibration is performed; during regenerative charging on a long downhill section, the increase in SOC is due to the recovery of kinetic energy from brake regenerative braking, not the actual charging state, and there is a high virtual power SOC, so the regenerative charging SOC cannot be calibrated to 100%; when the regenerative SOC exceeds the SOC full charge waiting value SOC_LIMIT, the battery SOC is limited to the SOC full charge waiting value SOC_LIMIT, where SOC_LIMIT<100%.

[0026] Furthermore, in step S4, the process of dynamic charging calibration is as follows:

[0027] S41, when the battery is low and needs to be charged, too much charging current will rapidly increase the single cell voltage. At this time, it is not suitable to perform dynamic charging calibration. The charging terminal should be dynamically calibrated when the current is moderate, that is, the absolute value of the charging current Cur_Chg should be greater than the current zero drift value CurDrift, and the absolute value of the charging current Cur_Chg should be less than the current multiple Crate_chg, wherein the current multiple Crate_chg is obtained by taking the quotient of the absolute value of the charging current Cur_Chg and the rated capacity Q of the battery. When step S41 is satisfied, continue to step S42;

[0028] S42, when the temperature is low, the discharge cut-off voltage of the battery is low, and its corresponding charging voltage threshold V_MAX_Chg is also low;

[0029] S43, when the battery is in a charging state, the highest cell voltage Vmax> the charging voltage threshold V_MAX_Chg for more than Dur_Time, and the target charging correction value SOCthr_Chg-displayed SOC≥charging SOC difference SOC_Diff_Chg, perform charging dynamic calibration, and correct the SOC to SOCthr_Chg-SOC_Diff_Chg at a correction rate Crt_rate3, where SOCthr_Chg<100%;

[0030] S44: When step S41 or S43 is not satisfied, charging dynamic calibration is not performed.

[0031] Furthermore, in the step S42, the charging voltage threshold V_MAX_Chg is selected according to the rule: when the lowest cell temperature Tmin≤temperature threshold T_MIN, V_MAX_Chg=low voltage threshold V_MAX_Low; when the lowest cell temperature Tmin>temperature threshold T_MIN, V_MAX_Chg=high voltage threshold V_MAX_High;

[0032] Furthermore, in step S5, the process of full charge calibration is as follows:

[0033] S51, when the highest cell voltage Vmax≥full charge cut-off voltage V_Fullchg, the timer Count starts counting;

[0034] S52, when the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging state and the charging current absolute value Cur_Chg ≤ current overcurrent alarm value Cur_Over, the battery is fully charged and calibrated to 100% SOC;

[0035] S53, when the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging state and the charging current absolute value Cur_Chg> current overcurrent alarm value Cur_Over, the full charge calibration is not performed, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT;

[0036] S54, when the timer Count ≥ full charge duration Fullchg_Time, the battery is in a charging state and has a discharge current, the full charge calibration and SOC limit are not performed, and the output displays the SOC value;

[0037] S55, when 0<timer Count<full charge duration Fullchg_Time and the battery is in a charging state, full charge calibration is not performed, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT;

[0038] S56. When the above S52, S53, S54, and S55 are not satisfied, full charge calibration and SOC limitation are not performed, and the SOC value is output and displayed.

[0039] Compared with the prior art, the present invention has the following advantages: the method of the present invention adopts the SOC capacity hiding method based on temperature, combined with the dynamic calibration of charge and discharge and the full charge calibration, to achieve accurate correction of the SOC of the power battery; the SOC is corrected based on the current rate, dynamic voltage, the difference between the displayed SOC and the target correction value, which is not affected by the current sampling accuracy and overcomes the cumulative error problem of the ampere-hour integration method; the SOC can be corrected in real time when the vehicle is operating, without the need to leave the battery stationary, which solves the dependence of the open circuit voltage method on stationary conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] like Figure 1 As shown, a method for correcting SOC in frequent uphill and downhill conditions includes the following steps:

[0043] Step 1. Obtain the hidden value SOC_Hide of the SOC capacity at different temperatures through a temperature lookup table, and calculate the displayed SOC value SOC_Disp, that is, the SOC at the current temperature, based on SOC_Hide and SOC_Pre estimated by the algorithm.

[0044] Among them, the process of SOC capacity hiding is as follows:

[0045] (1) When the temperature is low, the rated capacity at room temperature cannot be discharged due to the characteristics of the battery cell. The lower the temperature, the more capacity cannot be discharged, and the corresponding SOC capacity hidden value SOC_Hide is larger;

[0046] (2) Carry out discharge capacity tests at different temperatures, obtain the SOC capacity hidden value SOC_Hide table related to the temperature Temp, query the SOC_Hide table through temperature linear interpolation, and obtain the SOC_Hide corresponding to the current temperature Temp;

[0047] (3) The displayed SOC value SOC_Disp is calculated based on SOC_Hide and SOC_Pre estimated by the algorithm, that is, the SOC at the current temperature. The specific calculation formula is:

[0048]

[0049] Among them, SOC_Disp is the output display SOC value, SOC_Pre is the SOC value estimated by the algorithm, SOC_Hide is the SOC capacity hidden value, and the above SOCs are all calculated with %. When the SOC_Pre estimated by the algorithm is ≤ the SOC capacity hidden value SOC_Hide, the displayed SOC value SOC_Disp is 0%; when the SOC_Pre estimated by the algorithm is ≥100%, the displayed SOC value SOC_Disp is 100%.

[0050] In a specific embodiment, the temperature matrix Temp_Table = [-20, -10, 0, 10, 25] ° C, the SOC capacity hidden value table SOC_Hide_Table = [20, 15, 10, 5, 0]%, the current temperature Temp = -15 ° C, and the algorithm-estimated SOC_Pre = 80%. By looking up the SOC capacity hidden value table SOC_Hide_Table according to the current temperature Temp, the SOC_Hide corresponding to -15 ° C = 17.5%. According to formula (1), the displayed SOC value SOC_Disp = (80% -17.5%) / (100% -17.5%) = 75.8%, that is, the current SOC at -15 ° C.

[0051] Step 2: For long uphill sections, perform discharge dynamic calibration according to the difference between the current multiple Crate_dis, the minimum cell voltage Vmin, the displayed SOC value SOC_Disp and the target discharge correction value SOCthr_Dis.

[0052] The process of dynamic discharge calibration in this application is as follows:

[0053] (1) For long uphill sections, the battery discharge current is large. The large current will rapidly reduce the single cell voltage. At this time, dynamic calibration is not suitable. The dynamic calibration should be performed at the end of the discharge when the current is moderate, that is, the discharge current Cur_Dis should be greater than the current zero drift value CurDrift, and Cur_Dis should be less than the current multiple Crate_dis, where the current multiple Crate_dis is obtained by taking the quotient of the discharge current Cur_Dis and the battery rated capacity Q. When step (1) is satisfied, proceed to step (2).

[0054] (2) When the temperature is low, the SOC capacity hidden value SOC_Hide is used for calibration. When the minimum cell temperature Tmin> the temperature threshold T_MIN, the discharge dynamic calibration is performed. When step (2) is satisfied, step (3) is continued.

[0055] (3) When steps (1) and (2) are satisfied, and the minimum cell voltage Vmin≤discharge voltage threshold V_MIN_Dis for a duration of more than Dur_Time, and the display SOC-target discharge correction value SOCthr_Dis≥discharge SOC difference SOC_Diff_Dis, discharge dynamic calibration is performed. When the target discharge correction value SOCthr_Dis>0%, the SOC is corrected to SOCthr_Dis+SOC_Diff_Dis at the correction rate Crt_rate1; when the target discharge correction value SOCthr_Dis=0%, that is, the battery power is about to be exhausted, the SOC is corrected to 0% at the correction rate Crt_rate2, where Crt_rate2>Crt_rate1.

[0056] (4) When step (1), (2) or (3) is not satisfied, the discharge dynamics calibration is not performed.

[0057] It can be seen that for a long uphill section, when the current zero drift value CurDrift < discharge current Cur_Dis < current rate Crate_dis, the minimum cell temperature Tmin > temperature threshold T_MIN, the minimum cell voltage Vmin ≤ discharge voltage threshold V_MIN_Dis for more than Dur_Time, and the displayed SOC-target discharge correction value SOCthr_Dis ≥ discharge SOC difference SOC_Diff_Dis, the discharge dynamic calibration is performed.

[0058] In a specific embodiment, if the discharge current Cur_Dis=20A, the rated capacity of the battery Q=200Ah, the current zero drift value CurDrift=1A, the current rate Crate_dis=0.2C, the minimum cell temperature Tmin=10°C, the temperature threshold T_MIN=0°C, the minimum cell voltage Vmin=2.9V, the discharge voltage threshold V_MIN_Dis=3.0V, the duration threshold Dur_Time=5min, the actual Vmin is lower than 3.0V for 10min, the displayed SOC value SOC_Disp=30%, the target discharge correction value SOCthr_Dis=10%, the discharge SOC difference SOC_Diff_Dis=5%, the correction rate Crt_rate1=0.05% / s, and the correction rate Crt_rate2=0.1% / s:

[0059] Then the current ratio corresponding to the discharge current of 20A = discharge current Cur_Dis / battery rated capacity Q = 20 / 200C = 0.1C <current ratio Crate_dis = 0.2C, discharge current Cur_Dis = 20A> current zero drift value CurDrift = 1A, proceed to the next step; minimum cell temperature Tmin = 10℃ > temperature threshold T_MIN = 0℃, proceed to the next step; actual minimum cell voltage Vmin = 2.9V ≤ discharge voltage threshold V_MIN_Dis = 3.0V for 1 0min>Duration threshold Dur_Time=5min, display SOC-target discharge correction value SOCthr_Dis=30%-10%=20%≥discharge SOC difference SOC_Diff_Dis=5%, so discharge dynamic calibration is performed; because target discharge correction value SOCthr_Dis=10%>0%, so the SOC is corrected from 30% to SOCthr_Dis+SOC_Diff_Dis=10%+5%=15% at correction rate Crt_rate1=0.05% / s.

[0060] Step 3: For long downhill sections, the battery will be recharged. The recharged charging does not perform dynamic charging calibration, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT and below.

[0061] The regenerative charging limit is as follows: for long downhill sections, the battery will be regeneratively charged when the brakes are applied, and only ampere-hour integration is performed during regenerative charging, and no dynamic charging calibration is performed; during regenerative charging on a long downhill section, the increase in SOC is due to the recovery of kinetic energy from brake regenerative charging, not the actual charging state, and there is a high virtual power SOC, so the regenerative charging SOC cannot be calibrated to 100%; when the regenerative SOC exceeds the SOC full charge waiting value SOC_LIMIT, the battery SOC is limited to the SOC full charge waiting value SOC_LIMIT, where SOC_LIMIT<100%.

[0062] Step 4: When the battery is low and needs to be charged, a charging dynamic calibration is performed according to the difference between the current rate Crate_chg, the maximum cell voltage Vmax, the target charging correction value SOCthr_Chg and the displayed SOC value SOC_Disp.

[0063] Specifically, the process of charging dynamic calibration is as follows:

[0064] (1) When the battery is low and needs to be charged, too much charging current will rapidly increase the single cell voltage. At this time, it is not appropriate to perform dynamic charging calibration. The charging terminal should be dynamically calibrated when the current is moderate, that is, the absolute value of the charging current Cur_Chg should be greater than the current zero drift value CurDrift, and the absolute value of the charging current Cur_Chg should be less than the current multiple Crate_chg, where the current multiple Crate_chg is obtained by taking the quotient of the absolute value of the charging current Cur_Chg and the rated capacity Q of the battery. When step (1) is satisfied, proceed to the next step;

[0065] (2) When the temperature is low, the discharge cut-off voltage of the battery is low, and its corresponding charging voltage threshold V_MAX_Chg is also low. The selection rule of the charging voltage threshold V_MAX_Chg is: when the lowest cell temperature Tmin≤temperature threshold T_MIN, V_MAX_Chg=low voltage threshold V_MAX_Low; when the lowest cell temperature Tmin>temperature threshold T_MIN, V_MAX_Chg=high voltage threshold V_MAX_High.

[0066] (3) When the battery is in the charging state, the maximum cell voltage Vmax> the charging voltage threshold V_MAX_Chg for more than Dur_Time, and the target charging correction value SOCthr_Chg-displayed SOC≥charging SOC difference SOC_Diff_Chg, the charging dynamic calibration is performed, and the SOC is corrected to SOCthr_Chg-SOC_Diff_Chg at the correction rate Crt_rate3, where SOCthr_Chg<100%;

[0067] (4) When step (1) or (3) is not satisfied, charging dynamic calibration is not performed.

[0068] In a specific embodiment, for example, the absolute value of the charging current Cur_Chg=10A, the rated capacity of the battery Q=200Ah, the current zero drift value CurDrift=1A, the current rate Crate_chg=0.1C, the minimum cell temperature Tmin=-10°C, the temperature threshold T_MIN=0°C, the low voltage threshold V_MAX_Low=3.5V, the high voltage threshold V_MAX_High=3.53V, the battery is in a charging state, the maximum cell voltage Vmax=3.52V, the duration threshold Dur_Time=5min, the actual Vmax is higher than 3.5V for 10min, the displayed SOC value SOC_Disp=60%, the target charging correction value SOCthr_Chg=80%, the charging SOC difference SOC_Diff_Chg=3%, and the correction rate Crt_rate3=0.01% / s:

[0069] According to the above steps, the current ratio corresponding to the absolute value of the charging current of 10A = the absolute value of the charging current Cur_Chg / the rated capacity of the battery Q = 10 / 200C = 0.05C < the current ratio Crate_chg = 0.1C, the absolute value of the charging current Cur_Chg = 10A > the current zero drift value CurDrift = 1A, and the next step is continued; the minimum cell temperature Tmin = -10℃ ≤ the temperature threshold T_MIN = 0℃, so the charging voltage threshold V_MAX_Chg = the low voltage threshold V_MAX_Low = 3.5V, and the next step is continued; the battery is in Charging status, maximum single cell voltage Vmax = 3.52V> charging voltage threshold V_MAX_Chg = 3.5V for 10min> duration threshold Dur_Time = 5min, target charging correction value SOCthr_Chg-displayed SOC = 80%-60% = 20% ≥ charging SOC difference SOC_Diff_Chg = 3%, so perform charging dynamic calibration, and correct the SOC from 60% to SOCthr_Chg-SOC_Diff_Chg = 80%-3% = 77% at a correction rate Crt_rate3 = 0.01% / s.

[0070] Step 5: When the battery is in a charging state, the maximum single cell voltage Vmax ≥ the full charge cut-off voltage V_Fullchg for the full charge duration Fullchg_Time, and the charging current absolute value Cur_Chg ≤ the current overcurrent alarm value Cur_Over, perform full charge calibration on the battery and calibrate the SOC to 100%.

[0071] Specifically, the process of full charge calibration is as follows:

[0072] (1) When the highest cell voltage Vmax ≥ the full charge cut-off voltage V_Fullchg, the timer Count starts counting;

[0073] (2) When the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging (vehicle slow charging or charger fast charging) state and the charging current absolute value Cur_Chg ≤ current overcurrent alarm value Cur_Over, the battery is fully charged and calibrated to 100% SOC;

[0074] (3) When the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging (vehicle slow charging or charger fast charging) state and the charging current absolute value Cur_Chg > current overcurrent alarm value Cur_Over, the full charge calibration is not performed and the SOC is limited to the SOC full charge waiting value SOC_LIMIT;

[0075] (4) When the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging (vehicle slow charging or charger fast charging) state and there is discharge current, full charge calibration and SOC limit are not performed, and the output displays the SOC value;

[0076] (5) When 0<timer Count<full charge duration Fullchg_Time and the battery is in charging state, full charge calibration is not performed, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT;

[0077] (6) When the above steps (2), (3), (4), and (5) are not satisfied, full charge calibration and SOC limitation are not performed, and the SOC value is output and displayed.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for correcting SOC in frequent uphill and downhill conditions, characterized in that: The following steps are involved: S1. Obtain the hidden SOC capacity value SOC_Hide at different temperatures through temperature lookup table, and calculate the displayed SOC value SOC_Disp according to SOC_Hide and SOC_Pre estimated by the algorithm, that is, the SOC at the current temperature; S2. For a long uphill section, a discharge dynamic calibration is performed according to the difference between the current multiple Crate_dis, the minimum cell voltage Vmin, the displayed SOC value SOC_Disp and the target discharge correction value SOCthr_Dis; S3: For long downhill sections, the battery will be recharged. The recharged charging does not perform dynamic charging calibration, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT or below. S4. When the battery is low on power and needs to be charged, a dynamic charging calibration is performed according to the difference between the current rate Crate_chg, the maximum cell voltage Vmax, the target charging correction value SOCthr_Chg and the displayed SOC value SOC_Disp; S5. When the battery is in a charging state, the maximum single cell voltage Vmax ≥ the full charge cut-off voltage V_Fullchg for the full charge duration Fullchg_Time, and the charging current absolute value Cur_Chg ≤ the current overcurrent alarm value Cur_Over, the battery is fully charged and calibrated to 100% SOC.

2. The SOC correction method for frequent uphill and downhill conditions according to claim 1 is characterized in that: The process of hiding the SOC capacity in step S1 is as follows: S11. When the temperature is low, the rated capacity at room temperature cannot be discharged due to the characteristics of the battery cell. The lower the temperature, the more capacity cannot be discharged, and the corresponding SOC capacity hidden value SOC_Hide is larger; S12, carrying out discharge capacity tests at different temperatures, obtaining a SOC capacity hidden value SOC_Hide table related to the temperature Temp, looking up the SOC_Hide table by temperature linear interpolation, and obtaining the SOC_Hide corresponding to the current temperature Temp; S13. Calculate and display the SOC value SOC_Disp based on SOC_Hide and SOC_Pre estimated by the algorithm, that is, the SOC at the current temperature. The specific calculation formula is: Among them, SOC_Disp is the output displayed SOC value, SOC_Pre is the SOC value estimated by the algorithm, SOC_Hide is the SOC capacity hidden value, and the above SOCs are all calculated in %.

3. The SOC correction method for frequent uphill and downhill conditions according to claim 2 is characterized in that: In the step S13, when the SOC_Pre estimated by the algorithm is ≤ the SOC capacity hidden value SOC_Hide, the displayed SOC value SOC_Disp is 0%; when the SOC_Pre estimated by the algorithm is ≥100%, the displayed SOC value SOC_Disp is 100%.

4. The SOC correction method for frequent uphill and downhill conditions according to claim 2 is characterized in that: In step S2, the process of discharge dynamic calibration is as follows: S21. For long uphill sections, the battery discharge current is large. The large current will rapidly reduce the single cell voltage. At this time, dynamic calibration is not suitable. The discharge end should be dynamically calibrated when the current is moderate, that is, the discharge current Cur_Dis should be greater than the current zero drift value CurDrift, and Cur_Dis should be less than the current multiple Crate_dis, where the current multiple Crate_dis is obtained by taking the quotient of the discharge current Cur_Dis and the battery rated capacity Q. When step S21 is satisfied, continue to step S22; S22, when the temperature is low, calibration is performed based on the SOC capacity hidden value SOC_Hide, and when the lowest cell temperature Tmin> the temperature threshold T_MIN, discharge dynamic calibration is performed. When step S22 is satisfied, step S23 is continued; S23, when steps S21 and S22 are satisfied, and the minimum cell voltage Vmin≤discharge voltage threshold V_MIN_Dis for a duration of more than Dur_Time, and the displayed SOC-target discharge correction value SOCthr_Dis≥discharge SOC difference SOC_Diff_Dis, perform discharge dynamic calibration; S24: When step S21, S22 or S23 is not satisfied, the discharge dynamic calibration is not performed.

5. A method for correcting SOC in frequent uphill and downhill conditions according to claim 4, characterized in that: In step S23, when the target discharge correction value SOCthr_Dis>0%, the SOC is corrected to SOCthr_Dis+SOC_Diff_Dis at the correction rate Crt_rate1; when the target discharge correction value SOCthr_Dis=0%, that is, the battery power is about to be exhausted, the SOC is corrected to 0% at the correction rate Crt_rate2, where Crt_rate2>Crt_rate1.

6. The SOC correction method for frequent uphill and downhill conditions according to claim 1, characterized in that: In step S3, the regenerative charging is limited as follows: for long downhill sections, the battery will be regeneratively charged when the brakes are applied, and only ampere-hour integration is performed during regenerative charging, and no dynamic charging calibration is performed; during regenerative charging on a long downhill section, the increase in SOC is due to the recovery of kinetic energy from brake regenerative charging, not the actual charging state, and there is a high virtual power SOC, so the regenerative charging SOC cannot be calibrated to 100%; when the regenerative SOC exceeds the SOC full charge waiting value SOC_LIMIT, the battery SOC is limited to the SOC full charge waiting value SOC_LIMIT, where SOC_LIMIT<100%.

7. The SOC correction method for frequent uphill and downhill conditions according to claim 1 is characterized in that: In step S4, the process of dynamic charging calibration is as follows: S41, when the battery is low and needs to be charged, too much charging current will rapidly increase the single cell voltage. At this time, it is not suitable to perform dynamic charging calibration. The charging terminal should be dynamically calibrated when the current is moderate, that is, the absolute value of the charging current Cur_Chg should be greater than the current zero drift value CurDrift, and the absolute value of the charging current Cur_Chg should be less than the current multiple Crate_chg, wherein the current multiple Crate_chg is obtained by taking the quotient of the absolute value of the charging current Cur_Chg and the rated capacity Q of the battery. When step S41 is satisfied, continue to step S42; S42, when the temperature is low, the discharge cut-off voltage of the battery is low, and its corresponding charging voltage threshold V_MAX_Chg is also low; S43, when the battery is in a charging state, the highest cell voltage Vmax> the charging voltage threshold V_MAX_Chg for more than Dur_Time, and the target charging correction value SOCthr_Chg-displayed SOC≥charging SOC difference SOC_Diff_Chg, perform charging dynamic calibration, and correct the SOC to SOCthr_Chg-SOC_Diff_Chg at a correction rate Crt_rate3, where SOCthr_Chg<100%; S44: When step S41 or S43 is not satisfied, charging dynamic calibration is not performed.

8. The SOC correction method for frequent uphill and downhill conditions according to claim 7, characterized in that: In step S42 , the charging voltage threshold V_MAX_Chg is selected according to the following rule: when the lowest cell temperature Tmin≤temperature threshold T_MIN, V_MAX_Chg=low voltage threshold V_MAX_Low; when the lowest cell temperature Tmin>temperature threshold T_MIN, V_MAX_Chg=high voltage threshold V_MAX_High.

9. A method for correcting SOC in frequent uphill and downhill conditions according to claim 1, characterized in that: In step S5, the process of full charge calibration is as follows: S51, when the highest cell voltage Vmax≥full charge cut-off voltage V_Fullchg, the timer Count starts counting; S52, when the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging state and the charging current absolute value Cur_Chg ≤ current overcurrent alarm value Cur_Over, the battery is fully charged and calibrated to 100% SOC; S53, when the timer Count ≥ full charge duration Fullchg_Time, the battery is in charging state and the charging current absolute value Cur_Chg> current overcurrent alarm value Cur_Over, the full charge calibration is not performed, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT; S54, when the timer Count ≥ full charge duration Fullchg_Time, the battery is in a charging state and has a discharge current, the full charge calibration and SOC limit are not performed, and the output displays the SOC value; S55, when 0<timer Count<full charge duration Fullchg_Time and the battery is in a charging state, full charge calibration is not performed, and the SOC is limited to the SOC full charge waiting value SOC_LIMIT; S56. When the above S52, S53, S54, and S55 are not satisfied, full charge calibration and SOC limitation are not performed, and the SOC value is output and displayed.

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