CN116879822A - A SOC calibration method and related devices - Google Patents

Abstract

The invention provides an SOC calibration method and a related device, which are used for acquiring battery operation condition information, acquiring battery voltage information and battery SOC information under the condition that the battery operation condition information is judged to be preset operation condition information, and determining whether the battery voltage information and the battery SOC information both meet SOC calibration conditions or not, if so, performing SOC calibration operation to obtain an SOC reference value. According to the invention, when the battery operation condition is the preset operation condition, the SOC calibration operation can be performed without long-time standing of the battery, and the SOC calibration operation under the frequent charge and discharge scene of the battery is realized.

Description

A SOC calibration method and related devices

Technical field

The present invention relates to the field of SOC calibration, and more specifically, to an SOC calibration method and related devices.

Background technique

With the large-scale integration of new energy into the grid, the demand for energy storage is increasing. Battery energy storage is highly used due to its advantages such as high power density, fast response rate, and long service life.

In battery energy storage systems, battery SOC (state of charge) is a key indicator for stable long-term operation of the battery and needs to be calibrated. Currently, when performing SOC calibration, the battery needs to be left standing for a long time to obtain a more accurate SOC. However, in scenarios where the battery is frequently charged and discharged, such as frequency modulation scenarios, the condition of long standing still cannot be met. Then, how to achieve SOC calibration in a scenario of frequent battery charging and discharging is an urgent technical problem that technicians in the field need to solve.

Contents of the invention

In view of this, the present invention provides a SOC calibration method and related devices to solve the problem of urgent need to achieve SOC calibration in scenarios of frequent battery charging and discharging.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

A SOC calibration method including:

Obtain battery operating condition information;

When it is determined that the battery operating condition information is the preset operating condition information, obtain battery voltage information and battery SOC information;

Determine whether the battery voltage information and the battery SOC information both meet SOC calibration conditions;

If so, perform the SOC calibration operation to obtain the SOC reference value.

Optionally, obtain battery operating condition information, including:

Get the total current of the battery cluster;

When the total current is less than the preset current threshold, a timing operation is performed, and the timing time obtained by the timing operation is used as the battery rest time of the battery cluster.

Optionally, determining that the battery operating condition information is preset operating condition information includes:

When the value of the battery's resting time meets the preset short-time resting condition, it is determined that the battery operating condition information is the preset operating condition information.

Optionally, the preset short-time inactivity condition includes a preset inactivity short-time threshold, and the determination process of the preset inactivity short-time threshold includes:

Obtain the SOC dynamic threshold of each cell in the battery cluster, and filter out the smallest SOC dynamic threshold from the SOC dynamic threshold of each cell;

Based on the corresponding relationship between the minimum SOC dynamic threshold and the preset short-time static threshold, a table is looked up to determine the preset short-time static threshold corresponding to the minimum SOC dynamic threshold.

Optionally, obtain battery voltage information and battery SOC information, including:

Obtain the cell voltage of each cell in the battery cluster, and determine the minimum cell voltage based on the cell voltage of each cell;

Obtain the pre-calculated polarization voltage hysteresis and the pre-stored open circuit voltage value;

Obtain the SOC reference value, SOC dynamic threshold value and SOC static value of the cell corresponding to the minimum cell voltage.

Optionally, determining whether the battery voltage information and the battery SOC information both meet SOC calibration conditions includes:

Obtain non-platform period judgment rules;

Determine whether the battery cluster is in a non-platform period according to the battery voltage information, the battery SOC information and the non-platform period determination rules;

Wherein, when the battery cluster is in a non-platform period, it is determined that both the battery voltage information and the battery SOC information satisfy the SOC calibration conditions.

Optionally, judging whether the battery cluster is in a non-platform period according to the battery voltage information, the battery SOC information and the non-platform period determination rules includes:

Determine whether the sum of the minimum cell voltage and polarization voltage hysteresis is less than the open circuit voltage value, and determine whether the SOC reference value is greater than the sum of the SOC dynamic threshold and the SOC static value;

Wherein, the sum of the minimum cell voltage and the polarization voltage hysteresis is less than the open circuit voltage value, and the SOC reference value is greater than the sum of the SOC dynamic threshold and the SOC static value. In this case, it is determined that the battery cluster is in a non-platform period.

Optionally, perform SOC calibration operations to obtain SOC reference values, including:

Get the number of SOC calibrations;

When it is determined that the SOC calibration times meet the preset calibration times conditions, the SOC static value is used as the new SOC reference value.

Optionally, determining that the SOC calibration times meet the preset calibration times conditions includes:

Calculate the product of the number of SOC calibrations and the preset short-time standing threshold;

When the product is less than the preset long-term inactivity threshold, it is determined that the number of SOC calibrations meets the preset calibration times condition.

A battery management controller is used to perform the above SOC calibration method.

An energy storage system includes a battery cluster and the above-mentioned battery management controller.

Compared with the existing technology, the present invention has the following beneficial effects:

The present invention provides an SOC calibration method and related devices to obtain battery operating condition information. When it is determined that the battery operating condition information is preset operating condition information, battery voltage information and battery SOC information are obtained. Determine whether the battery voltage information and the battery SOC information both meet SOC calibration conditions. If so, perform an SOC calibration operation to obtain an SOC reference value. In the present invention, when the battery operating condition is the preset operating condition, the SOC calibration operation can be performed, and the battery does not need to be left standing for a long time, realizing the SOC calibration operation in the scenario of frequent battery charging and discharging.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a parallel energy storage system in the prior art;

Figure 2 is a method flow chart of an SOC calibration method provided by an embodiment of the present invention;

Figure 3 is a flow chart of a method for determining a preset short-time resting time threshold provided by an embodiment of the present invention;

Figure 4 is a flow chart of a method for obtaining battery voltage information and battery SOC information provided by an embodiment of the present invention;

Figure 5 is a flow chart of a method for determining whether the battery voltage information and the battery SOC information both meet SOC calibration conditions provided by an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

With the large-scale integration of new energy into the grid, the demand for energy storage is increasing. Battery energy storage is highly used due to its advantages such as high power density, fast response rate, and long service life.

Figure 1 shows a widely used parallel energy storage system, which consists of multiple battery cluster RACKs connected in parallel to expand capacity. Each RACK uses multiple battery module PACK packages (PACK1-PACKn) to increase the system voltage level. Finally, the entire Energy storage battery information management is summarized into the system BMS (BATTERY MANAGEMENTSYSTEM, battery management system) for decision-making. In this system, key information such as battery SOC becomes the key to the stable and long-term operation of lithium batteries and needs to be calibrated. The current mature algorithms mainly use OCV (open circuit voltage) combined with ampere-hour integration and other methods. However, this method has the following problems:

1. Currently, when performing SOC calibration, the battery needs to be left standing for a long time to obtain a more accurate SOC. However, for frequent battery charging and discharging scenarios, such as frequency modulation scenarios, it is impossible to achieve long-term standing conditions and cannot obtain accurate SOC values. , cannot meet the scheduling instructions and cannot achieve a better user experience.

2. The ampere-hour integration method is easily affected by the integration step size and current sampling accuracy. Among them, the error caused by current fluctuations is large, and the SOC of the system is prone to large deviations when the system works for a long time.

In order to solve the above problems, the present invention provides a SOC calibration method and related devices to obtain battery operating condition information, and obtain battery voltage information when it is determined that the battery operating condition information is preset operating condition information. and battery SOC information, determine whether the battery voltage information and the battery SOC information both meet SOC calibration conditions, and if so, perform an SOC calibration operation to obtain an SOC reference value. In the present invention, when the battery operating condition is the preset operating condition, the SOC calibration operation can be performed, and the battery does not need to be left standing for a long time, realizing the SOC calibration operation in the scenario of frequent battery charging and discharging. In addition, the present invention can avoid relatively complex differential and integral operations and is universal.

Based on the above content, an embodiment of the present invention provides a SOC calibration method, which can be applied to a battery management controller, such as the above-mentioned BMS.

Referring to Figure 2, a SOC calibration method may include:

S11. Obtain battery operating condition information.

In practical applications, after the battery energy storage system is turned on and running, the system will continue to run as long as there is no fault in the system. At this time, the battery operating conditions are obtained. The battery operating conditions may be in a low current operating state, etc.

Obtain battery operating condition information, which can include:

The total current of the battery cluster is obtained. When the total current is less than the preset current threshold, a timing operation is performed, and the timing time obtained by the timing operation is used as the battery rest time of the battery cluster.

Among them, the preset current threshold is the threshold of the low current operating state, such as 3A or 5A. That is to say, when the battery operating condition is a low current operating state, the duration of the low current operating state is obtained and used as the battery rest time of the battery cluster.

S12. When it is determined that the battery operating condition information is preset operating condition information, obtain battery voltage information and battery SOC information.

Specifically, when the value of the battery's resting time satisfies the preset short-time resting condition, it is determined that the battery operating condition information is the preset operating condition information.

Wherein, the preset short-time rest condition includes a preset short-time rest threshold. The value of the battery's rest time meets the preset short-time rest condition, which means that the value of the battery's rest time is greater than the preset short-time rest threshold.

In practical applications, if a small current is running, timing starts at this time. When the system timing time reaches the set value (such as the preset static short-time threshold time_set, the time_set has different values in different voltage ranges according to the system operation conditions. value), the battery operating condition information is considered to be the preset operating condition information, and the SOC calibration operation can be started.

In this embodiment, the preset short-time standstill threshold is related to the SOC dynamic threshold. Referring to Figure 3, the determination process of the preset short-time standstill threshold may include:

S21. Obtain the SOC dynamic threshold of each cell in the battery cluster, and select the smallest SOC dynamic threshold from the SOC dynamic threshold of each cell.

Specifically, because some lithium batteries have a "plateau" effect, and in practice, the relationship between the plateau voltage and SOC is not easy to judge due to sampling accuracy and other reasons, and there may be a many-to-one relationship, therefore, the present invention does not apply to the plateau range. The SOC is calibrated, and only the SOC in the non-plateau period is calibrated.

In this embodiment, the non-plateau area can be found by segmenting the open circuit voltage OCV curve at different temperatures.

In the non-platform period, the preset short-time static threshold time_set increases as the SOC dynamic threshold dynamic_threshold increases, and is limited to a certain range.

Specifically, the SOC dynamic threshold of each cell in each PACK package in the battery cluster can be obtained, and then the smallest SOC dynamic threshold can be selected from it to determine the preset short-time static threshold based on the smallest SOC dynamic threshold. .

S22. Based on the corresponding relationship between the minimum SOC dynamic threshold and the preset short-time static threshold, look up the table to determine the preset short-time static threshold corresponding to the minimum SOC dynamic threshold.

Specifically, the corresponding relationship between the minimum SOC dynamic threshold and the preset static short-time threshold can be configured in advance, and by subsequently checking the corresponding relationship, the preset static short-time threshold corresponding to the minimum SOC dynamic threshold can be obtained.

Further, when it is determined that the battery operating condition information is preset operating condition information, battery voltage information and battery SOC information are obtained.

In detail, refer to Figure 4 to obtain battery voltage information and battery SOC information, including:

S31. Obtain the cell voltage of each cell in the battery cluster, and determine the minimum cell voltage based on the cell voltage of each cell.

Among them, the minimum single cell voltage min_vol is the minimum single cell voltage in a RACK. Specifically, the cell voltage of each cell in the battery cluster is directly obtained, and then the minimum cell voltage is screened out.

S32. Obtain the precalculated polarization voltage hysteresis and the prestored open circuit voltage value.

Specifically, the polarization voltage hysteresis threshold_vol is the voltage hysteresis value obtained by combining the real-time polarization effect and the internal resistance of the cell. Specifically, it is calculated based on the current before the standstill moment, the internal resistance of the cell and the polarization effect. Voltage value, this value is mainly obtained by comparing with the OCV_Vol of the offline OCV-SOC table.

The open circuit voltage value OCV_Vol is the reference voltage value corresponding to OCV. Specifically, it is the voltage value obtained by inverting the current temperature according to the offline OCV table.

S33. Obtain the SOC reference value, SOC dynamic threshold value and SOC static value of the cell corresponding to the minimum cell voltage.

Among them, the SOC reference value AI_SOC refers to the SOC value used to correct the SOC display value in real time.

The SOC dynamic threshold dynamic_threshold is a compensation value obtained by comprehensive analysis of the SOC obtained by real-time calculation and the SOC obtained based on the current rest time table lookup.

The SOC static value OCV_SOC is the OCV static time, that is, the SOC value obtained after the preset long-term static threshold (OCV_TIME) is static, and is the SOC value after a long-term static value. The SOC can be obtained by looking up the table based on the current min_vol and temperature, marked as OCV_SOC.

S13. Determine whether the battery voltage information and the battery SOC information both meet the SOC calibration condition; if so, perform step S14.

Specifically, referring to Figure 5, determining whether the battery voltage information and the battery SOC information both meet the SOC calibration conditions may include:

S41. Obtain the non-platform period judgment rules.

Specifically, in the non-platform judgment rule, if the sum of the minimum single cell voltage and the polarization voltage hysteresis is less than the open circuit voltage value, and the SOC reference value is greater than the SOC dynamic threshold and the The sum of the SOC resting values determines that the battery cluster is in a non-platform period.

S42. Determine whether the battery cluster is in a non-platform period. If so, execute step S43.

Specifically, based on the battery voltage information, the battery SOC information and the non-platform period determination rule, it is determined whether the battery cluster is in a non-platform period.

Determining whether the battery cluster is in a non-platform period refers to determining whether the sum of the minimum single cell voltage and polarization voltage hysteresis is less than the open circuit voltage value, and whether the SOC reference value is greater than the sum of the SOC dynamic threshold and the SOC static value.

Wherein, the sum of the minimum cell voltage and the polarization voltage hysteresis is less than the open circuit voltage value, and the SOC reference value is greater than the sum of the SOC dynamic threshold and the SOC static value. In this case, it is determined that the battery cluster is in a non-platform period.

S43. Determine that both the battery voltage information and the battery SOC information meet the SOC calibration conditions.

Specifically, if the following two conditions are met at the same time:

1)min_vol+threshold_vol<OCV_Vol;

2)AI_SOC>OCV_SOC+dynamic_threshold.

It means that both the current battery voltage information and the battery SOC information meet the SOC calibration conditions, and the SOC calibration is started.

If either of the above two conditions is not met, or there is a fault in the system, the calibration operation will not be performed this time, and the calibration operation will be performed next time when the conditions are met.

S14. Perform SOC calibration operation to obtain the SOC reference value.

Specifically, the number of SOC calibrations is obtained, and when it is determined that the number of SOC calibrations meets the preset calibration number conditions, the SOC static value is used as the new SOC reference value.

In practical applications, in order to avoid the waste of resources caused by multiple calibrations during low current operation, the present invention limits the number of SOC calibrations. When the number of SOC calibrations is large, the calibration operation is stopped.

At this time, the number of SOC calibration times count is obtained, and the product of the number of SOC calibration times and the preset short-time standing threshold is calculated. When the product is less than the preset long-time standing threshold, it is determined that the number of SOC calibrations meets the preset number of calibrations. condition.

That is, when count*time_set<OCV_TIME is satisfied, it is considered that the calibration can continue, and the number of SOC calibrations meets the preset calibration number conditions. If count*time_set<OCV_TIME is not satisfied, it is considered that the number of calibrations is large, and the SOC calibration is stopped at this time.

When performing SOC calibration, the above-mentioned SOC static value is directly used as the SOC reference value, that is, the SOC value after a long period of static time is directly used as the SOC reference value. After the SOC is calibrated, a more accurate SOH (state of health, battery health) value can be obtained based on the calibrated SOC value.

After the SOC reference value is determined, the SOC display value is gradually adjusted to the SOC reference value according to a preset SOC display adjustment method.

Specifically, in order to avoid the problem of large SOC jump caused by directly adjusting the SOC display value to the SOC reference value and reducing the user experience. In this embodiment, the SOC display value is gradually adjusted to the SOC reference value according to a preset SOC display adjustment method, such as a gradual adjustment according to a specified jump value (for example, the SOC value increases by 5% each time).

In this embodiment, the battery operating condition information is obtained. When it is determined that the battery operating condition information is the preset operating condition information, the battery voltage information and the battery SOC information are obtained, and the battery voltage information and the battery SOC information are determined. Whether the above battery SOC information all meets the SOC calibration conditions, if so, perform the SOC calibration operation to obtain the SOC reference value. In the present invention, when the battery operating condition is the preset operating condition, the SOC calibration operation can be performed. The battery does not need to be left standing for a long time. It only needs to be left standing for a short time under low current operation to achieve a relatively fast and accurate calibration. Obtaining the SOC value enables SOC calibration operations in frequent battery charging and discharging scenarios, thereby improving system SOC accuracy and greatly improving system SOC accuracy and user experience. In addition, the present invention can avoid relatively complex differential and integral operations and is universal.

In addition, in the present invention, under frequency modulation working conditions, the system runs continuously and uses a short system intermittent time to complete the estimation of important parameters such as battery SOC, thereby improving user experience and system revenue.

Optionally, based on the above embodiment of the SOC calibration method, another embodiment of the present invention provides a battery management controller for executing the above SOC calibration method.

Specifically, a SOC calibration method includes:

Obtain battery operating condition information;

When it is determined that the battery operating condition information is the preset operating condition information, obtain battery voltage information and battery SOC information;

Determine whether the battery voltage information and the battery SOC information both meet SOC calibration conditions;

If so, perform the SOC calibration operation to obtain the SOC reference value.

Further, obtain battery operating condition information, including:

Get the total current of the battery cluster;

When the total current is less than the preset current threshold, a timing operation is performed, and the timing time obtained by the timing operation is used as the battery rest time of the battery cluster.

Further, it is determined that the battery operating condition information is preset operating condition information, including:

When the value of the battery's resting time meets the preset short-time resting condition, it is determined that the battery operating condition information is the preset operating condition information.

Further, the preset short-time resting condition includes a preset short-time resting threshold, and the determination process of the preset short-time resting threshold includes:

Obtain the SOC dynamic threshold of each cell in the battery cluster, and filter out the smallest SOC dynamic threshold from the SOC dynamic threshold of each cell;

Based on the corresponding relationship between the minimum SOC dynamic threshold and the preset short-time static threshold, a table is looked up to determine the preset short-time static threshold corresponding to the minimum SOC dynamic threshold.

Further, obtain battery voltage information and battery SOC information, including:

Obtain the cell voltage of each cell in the battery cluster, and determine the minimum cell voltage based on the cell voltage of each cell;

Obtain the pre-calculated polarization voltage hysteresis and the pre-stored open circuit voltage value;

Obtain the SOC reference value, SOC dynamic threshold value and SOC static value of the cell corresponding to the minimum cell voltage.

Further, determine whether the battery voltage information and the battery SOC information both meet SOC calibration conditions, including:

Obtain non-platform period judgment rules;

Determine whether the battery cluster is in a non-platform period according to the battery voltage information, the battery SOC information and the non-platform period determination rules;

Wherein, when the battery cluster is in a non-platform period, it is determined that both the battery voltage information and the battery SOC information satisfy the SOC calibration condition.

Further, judging whether the battery cluster is in a non-platform period according to the battery voltage information, the battery SOC information and the non-platform period determination rules includes:

Determine whether the sum of the minimum cell voltage and polarization voltage hysteresis is less than the open circuit voltage value, and determine whether the SOC reference value is greater than the sum of the SOC dynamic threshold and the SOC static value;

Wherein, the sum of the minimum cell voltage and the polarization voltage hysteresis is less than the open circuit voltage value, and the SOC reference value is greater than the sum of the SOC dynamic threshold and the SOC static value. In this case, it is determined that the battery cluster is in a non-platform period.

Further, perform the SOC calibration operation to obtain the SOC reference value, including:

Get the number of SOC calibrations;

When it is determined that the SOC calibration times meet the preset calibration times conditions, the SOC static value is used as the new SOC reference value.

Further, it is determined that the number of SOC calibrations meets the preset calibration number conditions, including:

Calculate the product of the number of SOC calibrations and the preset short-time standing threshold;

When the product is less than the preset long-term rest threshold, it is determined that the number of SOC calibrations meets the preset calibration number conditions.

In this embodiment, the battery operating condition information is obtained. When it is determined that the battery operating condition information is the preset operating condition information, the battery voltage information and the battery SOC information are obtained, and the battery voltage information and the battery SOC information are determined. Whether the above battery SOC information all meets the SOC calibration conditions, if so, perform the SOC calibration operation to obtain the SOC reference value. In the present invention, when the battery operating condition is the preset operating condition, the SOC calibration operation can be performed. The battery does not need to be left standing for a long time. It only needs to be left standing for a short time under low current operation to achieve a relatively fast and accurate calibration. Obtaining the SOC value enables SOC calibration operations in frequent battery charging and discharging scenarios, thereby improving system SOC accuracy and greatly improving system SOC accuracy and user experience. In addition, the present invention can avoid relatively complex differential and integral operations and is universal.

In addition, in the present invention, under frequency modulation working conditions, the system runs continuously and uses a short system intermittent time to complete the estimation of important parameters such as battery SOC, thereby improving user experience and system revenue.

Optionally, based on the above embodiment of the battery management controller, another embodiment of the present invention provides an energy storage system, including a battery cluster and the above battery management controller.

In this embodiment, the battery operating condition information is obtained. When it is determined that the battery operating condition information is the preset operating condition information, the battery voltage information and the battery SOC information are obtained, and the battery voltage information and the battery SOC information are determined. Whether the above battery SOC information all meets the SOC calibration conditions, if so, perform the SOC calibration operation to obtain the SOC reference value. In the present invention, when the battery operating condition is the preset operating condition, the SOC calibration operation can be performed. The battery does not need to be left standing for a long time. It only needs to be left standing for a short time under low current operation to achieve a relatively fast and accurate calibration. Obtaining the SOC value enables SOC calibration operations in frequent battery charging and discharging scenarios, thereby improving system SOC accuracy and greatly improving system SOC accuracy and user experience. In addition, the present invention can avoid relatively complex differential and integral operations and is universal.

In addition, in the present invention, under frequency modulation working conditions, the system runs continuously and uses a short system intermittent time to complete the estimation of important parameters such as battery SOC, thereby improving user experience and system revenue.

The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be practiced in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (11)

1. A SOC calibration method, comprising:

acquiring battery operation condition information;

under the condition that the battery operation condition information is judged to be preset operation condition information, battery voltage information and battery SOC information are obtained;

determining whether the battery voltage information and the battery SOC information both meet an SOC calibration condition;

if yes, performing SOC calibration operation to obtain an SOC reference value.

2. The SOC calibration method of claim 1, wherein obtaining battery operating condition information comprises:

acquiring the total current of the battery cluster;

and under the condition that the total current is smaller than a preset current threshold value, performing timing operation, and taking the timing time obtained by the timing operation as the standing time of the batteries of the battery cluster.

3. The SOC calibration method of claim 1, wherein determining that the battery operating condition information is preset operating condition information comprises:

and under the condition that the value of the battery standing time meets the preset short-time standing condition, judging that the battery operation condition information is the preset operation condition information.

4. The SOC calibration method of claim 3, wherein the preset short-time rest condition includes a preset rest short-time threshold, and the determining of the preset rest short-time threshold includes:

acquiring an SOC dynamic threshold value of each monomer in a battery cluster, and screening out a minimum SOC dynamic threshold value from the SOC dynamic threshold values of each monomer;

based on the corresponding relation between the minimum SOC dynamic threshold and the preset standing short time threshold, the table look-up determines the preset standing short time threshold corresponding to the minimum SOC dynamic threshold.

5. The SOC calibration method of claim 1, wherein obtaining battery voltage information and battery SOC information comprises:

acquiring the single cell voltage of each single cell in the battery cluster, and determining the minimum single cell voltage based on the single cell voltage of each single cell;

acquiring a pre-calculated polarization voltage return difference and a pre-stored open circuit voltage value;

and acquiring an SOC reference value, an SOC dynamic threshold value and an SOC standing value of the monomer corresponding to the minimum cell voltage.

6. The SOC calibration method of claim 1, wherein determining whether both the battery voltage information and the battery SOC information satisfy SOC calibration conditions comprises:

acquiring a non-platform period judgment rule;

judging whether a battery cluster is in a non-platform stage or not according to the battery voltage information, the battery SOC information and the non-platform stage judging rule;

and when the battery cluster is in a non-platform period, determining that the battery voltage information and the battery SOC information both meet the SOC calibration condition.

7. The SOC calibration method of claim 6, wherein determining whether a battery cluster is in a non-plateau based on the battery voltage information, the battery SOC information, and the non-plateau determination rule comprises:

judging whether the sum of the minimum cell voltage and the polarization voltage return difference is smaller than an open circuit voltage value or not, and judging whether the SOC reference value is larger than the sum of the SOC dynamic threshold value and the SOC standing value or not;

and determining that the battery cluster is in a non-platform stage under the condition that the sum of the minimum single cell voltage and the polarization voltage return difference is smaller than the open-circuit voltage value and the SOC reference value is larger than the sum of the SOC dynamic threshold value and the SOC standing value.

8. The SOC calibration method of claim 1, wherein performing an SOC calibration operation to obtain an SOC reference value comprises:

acquiring SOC calibration times;

and under the condition that the SOC calibration times meet the preset calibration times, taking the SOC standing value as a new SOC reference value.

9. The SOC calibration method of claim 8, wherein determining that the number of SOC calibrations satisfies a preset number of calibration conditions comprises:

calculating the product of the SOC calibration times and a preset standing short time threshold;

and under the condition that the product is smaller than a preset long-time standing threshold value, judging that the SOC calibration times meet the preset calibration times conditions.

10. A battery management controller configured to perform the SOC calibration method of any of claims 1-9.

11. An energy storage system comprising a battery cluster and the battery management controller of claim 10.