Sodium battery high and low temperature SOC calibration method

Abstract

The invention discloses a sodium battery high and low temperature SOC calibration method. The method comprises discharge dynamic calibration, discharge SOC empty calibration, SOC high and low temperature full charge calibration and standby calibration. According to the method, the discharge calibration rate is determined according to the current rate, null calibration is carried out on the SOC at the discharge tail end, meanwhile, full charge calibration is carried out on the SOC at the normal temperature and the low temperature, and accurate correction of the SOC of the sodium battery at the normal temperature and the low temperature is achieved; an empirical dynamic voltage and a discharge calibration rate are selected based on a current rate, and multi-interval correction is performed according to an SOC threshold value, so that the influence caused by a current sampling error is avoided, and the problem of an accumulated error of an ampere-hour integral method is overcome; and the SOC can be corrected in the full SOC interval in the standby low-current state, the vehicle does not need to be shut down and powered off, and the problem that a start-up calibration method depends on the standing working condition is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage battery application, and in particular relates to a high and low temperature SOC calibration method for a sodium battery. Background Art

[0002] Compared with lithium-ion batteries, sodium-ion batteries have the advantages of low cost and abundant reserves, and have attracted widespread attention in the field of new energy. When the cost of raw materials for lithium batteries is high, sodium batteries can be used in power batteries and energy storage fields due to their price advantage and excellent energy density. SOC (State of Charge) is an important indicator for measuring the safety performance of power batteries. The accurate calculation of the SOC of sodium batteries is directly related to the mileage of electric vehicles, which can avoid high-speed stalling caused by limited power, effectively prevent the vehicle from breaking down, and at the same time improve the user experience.

[0003] Common sodium battery SOC calibration methods in engineering include the ampere-hour integration method and the power-on calibration method. The ampere-hour integration method calculates the capacity based on the integral of current over time. The net capacity flowing into the battery is obtained by subtracting the capacity of the output battery from the capacity of the input battery. The SOC change is obtained by dividing this capacity by the rated capacity of the battery at room temperature. Because there are errors in current sampling, the error of the ampere-hour integration method will become larger and larger as time accumulates. The power-on calibration method is to calibrate the SOC according to the OCV (Open Circuit Voltage) of the battery after the battery is completely stationary for a period of time at the moment of power-on. The power-on calibration method requires the battery to be completely stationary for at least 1 hour, and cannot be performed during vehicle discharge operations. However, sometimes the vehicle needs to operate for a long time or consume power in standby mode, so the power-on calibration method is often restricted by factors such as stationary conditions, and it is difficult to correct the SOC in time. Summary of the invention

[0004] In order to make up for the shortcomings of the prior art, the present invention provides a high and low temperature SOC calibration method for a sodium battery. The discharge calibration rate is determined according to the current rate, and the SOC is calibrated at an empty state at the end of the discharge. At the same time, the SOC is fully calibrated at normal and low temperatures, thereby realizing accurate correction of the normal and low temperature SOC of the sodium battery.

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

[0006] The high and low temperature SOC calibration method of a sodium battery has the following specific steps:

[0007] S1. Discharge dynamic calibration: Carry out constant current discharge tests at different temperatures Temp and different current rates Crate, obtain dynamic voltages at different SOCs, select empirical dynamic voltages and discharge calibration rates according to the current rate range, and perform multi-range corrections according to the SOC threshold;

[0008] S2. Discharge SOC empty calibration: At the end of discharge, when SOC < 10%, remind the user to charge in time. When the battery is about to run out of power, perform an empty calibration on the SOC and calibrate the SOC to 0%;

[0009] S3.SOC high and low temperature full charge calibration: select different charging cut-off voltages according to normal temperature and low temperature conditions. When the highest cell voltage reaches the full charge cut-off voltage, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait;

[0010] S4. Standby calibration: When the standby time is ≥ the low current time threshold SLEEP_TIME, the current absolute value is ≤ the zero drift value CurDrift, and the SOC storage value SOC_Pre-SOCocv table lookup value SOCocv(Vavg) is ≥ the SOC error judgment value SOC_Error_thr, the standby calibration is performed to correct the SOC value to the SOCocv table lookup value SOCocv(Vavg).

[0011] Furthermore, the specific process of discharge dynamic calibration is as follows:

[0012] S11. Carry out constant current discharge tests under different temperatures Temp and different current rates Crate, and obtain the dynamic voltage values ​​corresponding to different SOCs under the corresponding temperature Temp and current rate Crate, that is, the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table three-dimensional matrix, and the dynamic voltage value is related to the temperature Temp, the current rate Crate, and the SOC, wherein the current rate matrix Crate_Table = [Crate3, Crate2, Crate1], the temperature matrix Temp_Table = [Temp3, Temp2, Temp1], and the SOC correction matrix SOC_Crt_Table = [SOC3, SOC2, SOC1];

[0013] S12. Select the empirical dynamic voltage and discharge calibration rate according to the current rate range. The larger the current rate Crate, the faster the calibration rate Kdis.

[0014] S13. The empirical dynamic voltage corresponding to different temperatures Temp and SOC is obtained by linear table lookup of the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table. When the average cell voltage Vavg ≤ the empirical dynamic voltage value Vdyn and the displayed SOC-SOC correction table value SOC_Crt ≥ the SOC discharge correction threshold SOC_Dis_thr, the dynamic calibration rate Kdis is accumulated on the basis of the ampere-hour integration to accelerate the correction of the SOC to SOC_Crt;

[0015] S14. When the SOC error is large (ie, the SOC error exceeds the SOC discharge correction threshold SOC_Dis_thr), a multi-interval acceleration correction is performed according to the SOC threshold until the SOC is calibrated to 10% or less.

[0016] Furthermore, the strategy for selecting the empirical dynamic voltage and discharge calibration rate is:

[0017] ① When the discharge current rate is greater than Crate1, no calibration is performed;

[0018] ② When the current ratio is in the interval of (Crate2, Crate1], the empirical dynamic voltage of Crate1 is selected for calibration, and the calibration rate Kdis is Kdis1;

[0019] ③ When the current ratio is in the interval of (Crate3, Crate2], the empirical dynamic voltage of Crate2 is selected for calibration, and the calibration rate Kdis is Kdis2;

[0020] ④ When the current ratio is in the range of (zero drift value CurDrift, Crate3], select the empirical dynamic voltage of Crate3 for calibration, and the calibration rate Kdis is Kdis3;

[0021] ⑤ When the current multiplier is in the range of [0, zero drift value CurDrift], no calibration is performed;

[0022] ⑥Calibration rate Kdis1>Kdis2>Kdis3.

[0023] Furthermore, the specific process of discharge SOC empty calibration is as follows:

[0024] S21. When the minimum cell voltage Vmin ≤ the low-power voltage reminder value V_Dis_Low and SOC < 10%, the charging reminder signal Chg_Rem_Signal is set to 1, and the display screen issues a low-battery warning to remind the user to charge in time;

[0025] S22. When the average cell voltage Vavg ≤ the average voltage low threshold V_Avg_Low, SOC ≤ the SOC low threshold SOC_Low, the minimum cell voltage Vmin ≤ the discharge cut-off voltage V_Dis_Empty and the duration Dur_Time ≥ the duration threshold DUR_TIME_THR, the display screen issues a battery exhaustion warning and calibrates the SOC to 0%.

[0026] Furthermore, the specific process of SOC high and low temperature full charge calibration is as follows:

[0027] S31. Under normal temperature (T≥0℃), when the highest cell voltage Vmax≥full charge cut-off high voltage Full_Volt_High, the battery is in charging state, and the current I<zero drift value CurDrift, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait, where SOC_Wait<100%;

[0028] S32. Under low temperature (T<0℃) conditions, when the highest cell voltage Vmax ≥ full charge cut-off low voltage Full_Volt_Low, the battery is in charging state, and the current I < zero drift value CurDrift, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait, where the full charge cut-off low voltage Full_Volt_Low < the full charge cut-off high voltage Full_Volt_High, and the SOC calibration waiting value SOC_Wait <100%.

[0029] Furthermore, the specific process of standby calibration is as follows:

[0030] S41. Sodium-ion batteries are different from lithium iron phosphate batteries. The OCV curve of sodium-ion batteries has no plateau period and can be calibrated in the entire SOC range. In the standby low current discharge state, the SOC is dynamically calibrated according to the discharge SOC-OCV curve.

[0031] S42. When the standby time is ≥ the low current time threshold SLEEP_TIME, the current absolute value is ≤ the zero drift value CurDrift, and the SOC storage value SOC_Pre-SOCocv table lookup value SOCocv(Vavg) is ≥ the SOC error judgment value SOC_Error_thr, the standby calibration is performed to correct the SOC value to the SOCocv table lookup value SOCocv(Vavg), where the SOC error judgment value SOC_Error_thr is obtained by looking up the SOC error judgment table SOC_Error_thr_Temp_Table through the temperature Temp. The lower the temperature, the larger the SOC error judgment value SOC_Error_thr.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] The high and low temperature SOC calibration method for a sodium battery of the present invention determines a discharge calibration rate according to a current multiple, performs an empty calibration on the SOC at the end of the discharge, and performs a full charge calibration on the SOC at normal temperature and low temperature, thereby realizing accurate correction of the normal temperature and low temperature SOC of the sodium battery; selects empirical dynamic voltage and discharge calibration rate based on the current multiple, performs multi-interval correction according to the SOC threshold, avoids the influence of current sampling error, and overcomes the cumulative error problem of the ampere-hour integration method; and can correct the SOC in the full SOC interval in a low current standby state, without shutting down the vehicle, thereby solving the dependence of the power-on calibration method on static working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flowchart of the SOC calibration method of the present invention. DETAILED DESCRIPTION

[0035] 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.

[0036] like Figure 1 As shown, a sodium battery high and low temperature SOC calibration method, the specific steps are as follows:

[0037] (I) Discharge dynamic calibration: Carry out constant current discharge tests at different temperatures Temp and different current rates Crate, obtain the dynamic voltage at different SOCs, select the empirical dynamic voltage and discharge calibration rate according to the current rate range, and perform multi-range correction according to the SOC threshold.

[0038] The specific process of discharge dynamic calibration is as follows:

[0039] (1) Carry out constant current discharge tests under different temperatures Temp and different current rates Crate, and obtain the dynamic voltage values ​​corresponding to different SOCs under the corresponding temperature Temp and current rate Crate, that is, the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table three-dimensional matrix. The dynamic voltage value is related to the temperature Temp, current rate Crate, and SOC, among which the current rate matrix Crate_Table = [Crate3, Crate2, Crate1], the temperature matrix Temp_Table = [Temp3, Temp2, Temp1], and the SOC correction matrix SOC_Crt_Table = [SOC3, SOC2, SOC1].

[0040] (2) Select the empirical dynamic voltage and discharge calibration rate according to the current rate range. The larger the current rate Crate, the faster the calibration rate Kdis.

[0041] ① When the discharge current rate is greater than Crate1, no calibration is performed;

[0042] ② When the current ratio is in the interval of (Crate2, Crate1], the empirical dynamic voltage of Crate1 is selected for calibration, and the calibration rate Kdis is Kdis1;

[0043] ③ When the current ratio is in the interval of (Crate3, Crate2], the empirical dynamic voltage of Crate2 is selected for calibration, and the calibration rate Kdis is Kdis2;

[0044] ④ When the current ratio is in the range of (zero drift value CurDrift, Crate3], select the empirical dynamic voltage of Crate3 for calibration, and the calibration rate Kdis is Kdis3;

[0045] ⑤ When the current multiplier is in the range of [0, zero drift value CurDrift], no calibration is performed;

[0046] ⑥Calibration rate Kdis1>Kdis2>Kdis3.

[0047] (3) The empirical dynamic voltage corresponding to different temperatures Temp and SOC is obtained through linear table lookup of the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table. When the average cell voltage Vavg ≤ the empirical dynamic voltage value Vdyn and the displayed SOC-SOC correction table value SOC_Crt ≥ the SOC discharge correction threshold SOC_Dis_thr, the dynamic calibration rate Kdis is accumulated on the basis of the ampere-hour integration to accelerate the SOC correction to SOC_Crt.

[0048] (4) When the SOC error is large (ie, the SOC error exceeds the SOC discharge correction threshold SOC_Dis_thr), a multi-interval acceleration correction is performed according to the SOC threshold until the SOC is calibrated to 10% or less.

[0049] For step (1), in a specific embodiment, if the temperature matrix Temp_Table = [-20, 0, 25] ° C, the current rate matrix Crate_Table = [0.1, 0.2, 0.5] C, and the SOC correction matrix SOC_Crt_Table = [50, 30, 10]%, since the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table three-dimensional matrix is ​​difficult to display in a plane, it is expanded according to different current rates. The empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table1 corresponding to the current multiple of 0.5C is [2.86, 2.92, 3.0; 2.5, 2.54, 2.7; 2.1, 2.16, 2.2] V, wherein the first line is the SOC threshold voltages at three temperature points corresponding to 50% SOC, the second line is the SOC threshold voltages at three temperature points corresponding to 30% SOC, and the third line is the SOC threshold voltages at three temperature points corresponding to 10% SOC, the same below; the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table2 corresponding to the current multiple of 0.2C is [2.95, 3.0, 3.05; 2.55, 2.6, 2.75; 2.15,2.2,2.25]V, the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table3 corresponding to the current rate of 0.1C = [3.0,3.05,3.1; 2.6,2.7,2.8; 2.2,2.25,2.3]V, Kdis1 = 0.02% / s, Kdis2 = 0.01% / s, Kdis3 = 0.005% / s, actual current I = 50A, zero drift value CurDrift = 1A, battery capacity Q0 = 200Ah, actual temperature Temp = -10℃, average single cell voltage Vavg = 2.1V, displayed SOC = 70%, SOC discharge correction threshold SOC_Dis_thr = 10%:

[0050] According to step (2), the current rate Crate = I / Q0 = 50 / 200C = 0.25C is within the range of (0.2, 0.5]C, so the 0.5C empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table1 = [2.86, 2.92, 3.0; 2.5, 2.54, 2.7; 2.1, 2.16, 2.2]V is selected for calibration, Kdis1 = 0.02% / s;

[0051] According to step (3), the actual temperature Temp = -10°C, and the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table1 = [2.86, 2.92, 3.0; 2.5, 2.54, 2.7; 2.1, 2.16, 2.2] V is checked by linear interpolation. The empirical dynamic voltage corresponding to -10°C is between -20°C and 0°C, which is [2.89, 2.52, 2.13] V; the average cell voltage Vavg =2.1V≤50% SOC corresponding to the empirical dynamic voltage value Vdyn1=2.89V, display SOC-SOC correction table value SOC_Crt1=70%-50%=20%≥SOC discharge correction threshold SOC_Dis_thr=10%, so on the basis of ampere-hour integration, accumulate Kdis1=0.02% / s dynamic calibration rate, accelerate the correction of SOC to SOC_Crt1=50%, that is, display SOC=50%;

[0052] According to step (4), after the SOC is corrected to 50%, it is determined whether further correction is required. The average cell voltage Vavg = 2.1V ≤ 30% SOC corresponding to the empirical dynamic voltage value Vdyn2 = 2.52V, and the displayed SOC-SOC correction table value SOC_Crt2 = 50% - 30% = 20% ≥ SOC discharge correction threshold SOC_Dis_thr = 10%, so further correction is still required. On the basis of the ampere-hour integration, the dynamic calibration rate Kdis1 = 0.02% / s is accumulated to accelerate the correction of the SOC to SOC_Crt2 = 30%, that is, the displayed SOC = 30%;

[0053] According to step (4), after the SOC is corrected to 30%, it is determined whether further correction is needed. The average cell voltage Vavg = 2.1V≤10% SOC corresponds to the empirical dynamic voltage value Vdyn3 = 2.13V, and the displayed SOC-SOC correction table value SOC_Crt3 = 30%-10% = 20% ≥ SOC discharge correction threshold SOC_Dis_thr = 10%. Therefore, further correction is still needed. On the basis of the ampere-hour integration, the dynamic calibration rate Kdis1 = 0.02% / s is accumulated to accelerate the SOC correction to SOC_Crt3 = 10%, that is, the displayed SOC = 10%.

[0054] (ii) Discharge SOC empty calibration: At the end of discharge when SOC < 10%, the user is reminded to charge in time. When the battery is about to run out of power, the SOC is empty calibrated to 0%.

[0055] The specific process of discharge SOC empty calibration is as follows:

[0056] (1) When the minimum cell voltage Vmin ≤ the low-battery voltage reminder value V_Dis_Low and the SOC < 10%, the charging reminder signal Chg_Rem_Signal is set to 1, and the display screen issues a low-battery warning to remind the user to charge in time;

[0057] (2) When the average cell voltage Vavg ≤ the average voltage low threshold V_Avg_Low, SOC ≤ the SOC low threshold SOC_Low, the minimum cell voltage Vmin ≤ the discharge cut-off voltage V_Dis_Empty and the duration Dur_Time ≥ the duration threshold DUR_TIME_THR, the display screen issues a battery exhaustion warning and calibrates the SOC to 0%.

[0058] (III) SOC high and low temperature full charge calibration: Select different charging cut-off voltages according to normal temperature and low temperature conditions. When the highest cell voltage reaches the full charge cut-off voltage, the SOC is calibrated to 100%. Otherwise, the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait.

[0059] The specific process of SOC high and low temperature full charge calibration is as follows:

[0060] (1) Under normal temperature (i.e., T ≥ 0°C), when the maximum cell voltage Vmax ≥ the full charge cut-off high voltage Full_Volt_High, the battery is in the charging state, and the current I < the zero drift value CurDrift, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait, where SOC_Wait < 100%;

[0061] (2) Under low temperature conditions (i.e., T<0°C), when the maximum cell voltage Vmax ≥ the full charge cut-off low voltage Full_Volt_Low, the battery is in a charging state, and the current I < the zero drift value CurDrift, the SOC is calibrated to 100%. Otherwise, the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait, where the full charge cut-off low voltage Full_Volt_Low < the full charge cut-off high voltage Full_Volt_High, and the SOC calibration waiting value SOC_Wait < 100%.

[0062] (iv) Standby calibration: When the standby time is ≥ the low current time threshold SLEEP_TIME, the current absolute value is ≤ the zero drift value CurDrift, and the SOC storage value SOC_Pre-SOCocv table lookup value SOCocv(Vavg) is ≥ the SOC error judgment value SOC_Error_thr, the standby calibration is performed to correct the SOC value to the SOCocv table lookup value SOCocv(Vavg).

[0063] Sodium-ion batteries are different from lithium iron phosphate batteries. The OCV curve of sodium-ion batteries has no plateau period and can be calibrated in the entire SOC range. The specific process of standby calibration is as follows:

[0064] (1) In the standby low current discharge state, the SOC is dynamically calibrated according to the discharge SOC-OCV curve;

[0065] (2) When the standby time is ≥ the low current time threshold SLEEP_TIME, the current absolute value is ≤ the zero drift value CurDrift, and the SOC storage value SOC_Pre-SOCocv table lookup value SOCocv(Vavg) is ≥ the SOC error judgment value SOC_Error_thr, the standby calibration is performed to correct the SOC value to the SOCocv table lookup value SOCocv(Vavg), where the SOC error judgment value SOC_Error_thr is obtained by looking up the SOC error judgment table SOC_Error_thr_Temp_Table through the temperature Temp. The lower the temperature, the larger the SOC error judgment value SOC_Error_thr.

[0066] For the standby calibration in step (iv), there are the following specific embodiments:

[0067] If the standby time St_Time = 150min, the low current time threshold SLEEP_TIME = 60min, the actual current I = 0.2A, the zero drift value CurDrift = 1A, the SOC storage value SOC_Pre = 90%, the average cell voltage Vavg = 3.4V, SOCocv (3.4V) = 70%, the SOC error judgment table SOC_Error_thr_Temp_Table = [20, 14, 10, 5]%, the temperature matrix Temp_Table = [-10, 0, 10, 25]℃, and the actual temperature Temp = -5℃:

[0068] Actual temperature Temp = -5℃ linear interpolation looks up SOC error judgment table SOC_Error_thr_Temp_Table, corresponding SOC error judgment value SOC_Error_thr = 17%, standby low current time St_Time = 150min ≥ low current time threshold SLEEP_TIME = 60min, current absolute value I = 0.2A ≤ zero drift value CurDrift = 1A, SOC storage value SOC_Pre-SOCocv table lookup value SOCocv (Vavg) = 90% -70% = 20% ≥ SOC error judgment value SOC_Error_thr = 17%, so standby calibration is performed to correct the SOC value to SOCocv table lookup value SOCocv (Vavg) = 70%.

[0069] In summary, the high and low temperature SOC calibration method of the sodium battery of the present invention determines the discharge calibration rate according to the current ratio, performs an empty calibration on the SOC at the end of the discharge, and performs a full charge calibration on the SOC at room temperature and low temperature, thereby realizing accurate correction of the room temperature and low temperature SOC of the sodium battery; based on the current ratio, the empirical dynamic voltage and discharge calibration rate are selected, and multi-interval correction is performed according to the SOC threshold to avoid the influence of the current sampling error; and the SOC can be corrected in the full SOC interval in the standby low current state, without shutting down the vehicle, thereby solving the dependence of the power-on calibration method on the static working condition.

[0070] 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 sodium battery high and low temperature SOC calibration method, characterized in that: The specific steps are as follows: S1. Discharge dynamic calibration: Carry out constant current discharge tests at different temperatures Temp and different current rates Crate, obtain dynamic voltages at different SOCs, select empirical dynamic voltages and discharge calibration rates according to the current rate range, and perform multi-range corrections according to the SOC threshold; S2. Discharge SOC empty calibration: At the end of discharge, when SOC < 10%, remind the user to charge in time. When the battery is about to run out of power, perform an empty calibration on the SOC and calibrate the SOC to 0%; S3.SOC high and low temperature full charge calibration: select different charging cut-off voltages according to normal temperature and low temperature conditions. When the highest cell voltage reaches the full charge cut-off voltage, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait; S4. Standby calibration: When the standby time is ≥ the low current time threshold SLEEP_TIME, the current absolute value is ≤ the zero drift value CurDrift, and the SOC storage value SOC_Pre-SOCocv table lookup value SOCocv(Vavg) is ≥ the SOC error judgment value SOC_Error_thr, the standby calibration is performed to correct the SOC value to the SOCocv table lookup value SOCocv(Vavg).

2. A sodium battery high and low temperature SOC calibration method according to claim 1, characterized in that: In step S1, the specific process of discharge dynamic calibration is as follows: S11. Carry out constant current discharge tests under different temperatures Temp and different current rates Crate, and obtain the dynamic voltage values ​​corresponding to different SOCs under the corresponding temperature Temp and current rate Crate, that is, the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table three-dimensional matrix, and the dynamic voltage value is related to the temperature Temp, the current rate Crate, and the SOC, wherein the current rate matrix Crate_Table = [Crate3, Crate2, Crate1], the temperature matrix Temp_Table = [Temp3, Temp2, Temp1], and the SOC correction matrix SOC_Crt_Table = [SOC3, SOC2, SOC1]; S12. Selecting empirical dynamic voltage and discharge calibration rate according to the current rate range; S13. The empirical dynamic voltage corresponding to different temperatures Temp and SOC is obtained by linear table lookup of the empirical dynamic voltage matrix Vdyn_Temp_Crate_SOC_Table. When the average cell voltage Vavg ≤ the empirical dynamic voltage value Vdyn and the displayed SOC-SOC correction table value SOC_Crt ≥ the SOC discharge correction threshold SOC_Dis_thr, the dynamic calibration rate Kdis is accumulated on the basis of the ampere-hour integration to accelerate the correction of the SOC to SOC_Crt; S14. When the SOC error exceeds the SOC discharge correction threshold SOC_Dis_thr, a multi-interval acceleration correction is performed according to the SOC threshold until the SOC is calibrated to 10% or less.

3. A sodium battery high and low temperature SOC calibration method according to claim 2, characterized in that: In step S12, the strategy for selecting the empirical dynamic voltage and discharge calibration rate is: ① When the discharge current rate is greater than Crate1, no calibration is performed; ② When the current ratio is in the interval of (Crate2, Crate1], the empirical dynamic voltage of Crate1 is selected for calibration, and the calibration rate Kdis is Kdis1; ③ When the current ratio is in the interval of (Crate3, Crate2], the empirical dynamic voltage of Crate2 is selected for calibration, and the calibration rate Kdis is Kdis2; ④ When the current ratio is in the range of (zero drift value CurDrift, Crate3], select the empirical dynamic voltage of Crate3 for calibration, and the calibration rate Kdis is Kdis3; ⑤ When the current multiplier is in the range of [0, zero drift value CurDrift], no calibration is performed; ⑥Calibration rate Kdis1>Kdis2>Kdis3.

4. A sodium battery high and low temperature SOC calibration method according to claim 1, characterized in that: In step S2, the specific process of discharge SOC empty calibration is as follows: S21. When the minimum cell voltage Vmin≤the low-power voltage reminder value V_Dis_Low and the SOC<10%, the charging reminder signal Chg_Rem_Signal is set to 1, and the user is reminded to charge in time; S22. When the average cell voltage Vavg ≤ the average voltage low threshold V_Avg_Low, the SOC ≤ the SOC low threshold SOC_Low, the minimum cell voltage Vmin ≤ the discharge cut-off voltage V_Dis_Empty and the duration Dur_Time ≥ the duration threshold DUR_TIME_THR, a battery power exhaustion alarm is issued and the SOC is calibrated to 0%.

5. A sodium battery high and low temperature SOC calibration method according to claim 1, characterized in that: In step S3, the specific process of SOC high and low temperature full charge calibration is as follows: S31. When the temperature T ≥ 0°C, when the highest cell voltage Vmax ≥ the full charge cut-off high voltage Full_Volt_High, the battery is in the charging state, and the current I < the zero drift value CurDrift, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait, where the SOC calibration waiting value SOC_Wait < 100%; S32. When the temperature T is less than 0°C, when the highest cell voltage Vmax ≥ the full charge cut-off low voltage Full_Volt_Low, the battery is in a charging state, and the current I < the zero drift value CurDrift, the SOC is calibrated to 100%, otherwise the SOC upper limit is limited to the SOC calibration waiting value SOC_Wait, wherein the full charge cut-off low voltage Full_Volt_Low < the full charge cut-off high voltage Full_Volt_High, and the SOC calibration waiting value SOC_Wait < 100%.

6. A sodium battery high and low temperature SOC calibration method according to claim 1, characterized in that: In step S4, the specific process of standby calibration is as follows: S41. In the standby low current discharge state, the SOC is dynamically calibrated according to the discharge SOC-OCV curve; S42. When the standby time is ≥ the small current time threshold SLEEP_TIME, the current absolute value is ≤ the zero drift value CurDrift, and the SOC storage value SOC_Pre-SOCocv table lookup value SOCocv(Vavg) is ≥ the SOC error judgment value SOC_Error_thr, the standby calibration is performed to correct the SOC value to the SOCocv table lookup value SOCocv(Vavg), wherein the SOC error judgment value SOC_Error_thr is obtained by looking up the SOC error judgment table SOC_Error_thr_Temp_Table through the temperature Temp, and the lower the temperature, the larger the SOC error judgment value SOC_Error_thr.

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