A method and system for calibrating the state of charge of a power battery

Abstract

The application provides a power battery SOC calibration method and system, comprising: controlling a vehicle to discharge to a V2G charging pile, and entering a first stationary state after the discharge ends; obtaining empty state data of the power battery, and controlling the vehicle to perform a first balancing operation; controlling the V2G charging pile to charge the vehicle, and controlling the vehicle to enter a second stationary state after the charging ends; obtaining full charge state data of the power battery, and controlling the vehicle to perform a second balancing operation; determining this time of charge-discharge cycle data according to initial state data, empty state data, full charge state data, the first balancing operation and the second balancing operation of the power battery; and calibrating the power battery SOC of the vehicle according to the charge-discharge cycle data. The application can effectively improve the power battery SOC calibration precision and convenience.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicle power devices, or to the technical field of circuit devices or systems for power supply or power distribution, and in particular to a power battery SOC calibration method and system. BACKGROUND

[0002] With the development of the integration of electric vehicles and V2G (Vehicle-to-Grid) technology, the SOC (State of Charge) estimation accuracy of the power battery, as the core energy storage unit of the V2G system, directly affects the grid load regulation, vehicle travel range and battery safety. The existing power battery SOC calibration methods are mostly limited to non-V2G scenarios. The mainstream SOC calibration method in the industry currently relies on special equipment in 4S stores for complete charge-discharge cycling, or the vehicle owner calibrates it by himself through self-charging and discharging.

[0003] The existing power battery SOC calibration scheme has the following defects: 4S store calibration requires sending the vehicle to a designated location, and each calibration takes 4-8 hours, requires professional equipment, professional personnel operation and labor cost; vehicle owner calibration is time-consuming and mostly based on shallow charging and discharging, which can only correct local interval errors and cannot solve the depth deviation, and the state information of the battery during charging and discharging cannot be controlled; the idle rate of special equipment is high, the electric energy consumed in the calibration process is not used in coordination with the grid, and the resource utilization rate is low; it is impossible to perform differentiated SOC calibration strategies for different battery types (such as ternary lithium batteries and iron phosphate lithium batteries). In addition, in the existing SOC calibration scheme based on charge-discharge cycling, the emptying and / or full charging state data collected is easily affected by polarization interference or cell consistency differences, which distorts the correction reference of the SOC estimation algorithm and makes it difficult to achieve high-precision calibration of the SOC. SUMMARY

[0004] The present application provides a power battery SOC calibration method and system, which controls the target vehicle to complete the complete cycle of discharging, first static equalization, charging, and second static equalization in the V2G charge-discharge system, obtains real charge-discharge data, and eliminates cell voltage differences and polarization interference through two static equalizations to ensure the accuracy of the emptying and full charging state data; and based on the multi-dimensional state data and equalization operation information, constructs the charge-discharge cycle data, and finally realizes the accurate calibration of the power battery SOC, effectively improving the SOC estimation accuracy.

[0005] In a first aspect, the present application provides a power battery SOC calibration method applied to a server of a first charge-discharge platform in a charge-discharge system, wherein the first charge-discharge platform includes a plurality of V2G charging piles, the charge-discharge system further includes a target vehicle, the V2G charging pile is connected with the target vehicle, and the target vehicle includes the power battery; the method includes:

[0006] controlling the target vehicle to discharge to the V2G charging pile, and entering a first stationary state after the discharging ends;

[0007] obtaining empty state data of the power battery, and controlling the target vehicle to perform a first balancing operation according to the empty state data, so that a voltage difference between any two cells in the power battery is less than a first preset threshold;

[0008] controlling the V2G charging pile to charge the target vehicle, and controlling the target vehicle to enter a second stationary state after the charging ends;

[0009] obtaining full charge state data of the power battery, and controlling the target vehicle to perform a second balancing operation according to the full charge state data, so that the voltage difference between any two cells in the power battery is less than a second preset threshold;

[0010] determining this time charging and discharging cycle data of the target vehicle according to the initial state data, the empty state data, the full charge state data, the first balancing operation and the second balancing operation of the power battery, and calibrating the power battery SOC of the target vehicle according to the charging and discharging cycle data.

[0011] In a second aspect, an embodiment of the present application provides a charging and discharging system, including a first charging and discharging platform, the first charging and discharging platform including a plurality of V2G charging piles and a server, the charging and discharging system further including a target vehicle, the V2G charging pile being connected with the target vehicle, the target vehicle including a power battery, wherein the server is configured to perform the steps of the method of the first aspect.

[0012] In a third aspect, an embodiment of the present application provides an electronic device, including a processor, a memory, and one or more programs, the one or more programs being stored in the memory and configured to be executed by the processor, the program including instructions for performing the steps in the first aspect of the present application.

[0013] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, having stored thereon a computer program or instructions, the computer program or instructions being executed by a processor to perform the steps of the method of the first aspect.

[0014] It can be seen that in the embodiments of the present application, the server controls the target vehicle to discharge to the V2G charging pile, and enters the first stationary state after the discharge is completed; obtains the empty state data of the power battery, and controls the target vehicle to perform the first balancing operation according to the empty state data, so that the voltage difference between any two cells in the power battery is less than the first preset threshold; controls the V2G charging pile to charge the target vehicle, and controls the target vehicle to enter the second stationary state after the charging is completed; obtains the full charge state data of the power battery, and controls the target vehicle to perform the second balancing operation according to the full charge state data, so that the voltage difference between any two cells in the power battery is less than the second preset threshold; determines the current charging and discharging cycle data of the target vehicle according to the initial state data, the empty state data, the full charge state data, the first balancing operation and the second balancing operation of the power battery; and calibrates the power battery SOC of the target vehicle according to the charging and discharging cycle data. Thus, compared with the existing power battery SOC calibration scheme, the present application realizes high-precision SOC calibration adapted to bidirectional energy interaction by complete charging and discharging cycle and twice stationary balancing in the V2G scenario, and corrects the state data in combination with the balancing process data, solves the problem of insufficient SOC calibration precision caused by one-sided data and non-optimized consistency in the traditional scheme. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 is a system architecture diagram of a charging and discharging system provided by an embodiment of the present application;

[0017] Figure 2 is a step flow chart of a power battery SOC calibration method provided by an embodiment of the present application;

[0018] Figure 3 is a flowchart of determining vehicle charging and discharging cycle data provided by an embodiment of the present application;

[0019] Figure 4 is a flowchart of calibrating the power battery SOC based on the charging and discharging cycle data provided by an embodiment of the present application;

[0020] Figure 5 is a whole flowchart of a power battery SOC calibration method provided by an embodiment of the present application;

[0021] Figure 6is an application scenario of a power battery SOC calibration method provided by an embodiment of the present application;

[0022] Figure 7 is a functional unit block diagram of a charge-discharge system provided by an embodiment of the present application;

[0023] Figure 8 is a structural block diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to enable persons skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative work fall within the scope of protection of the present application.

[0025] The terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product, or device.

[0026] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily mutually exclusive or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the embodiments of the present application, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships. For example, A and / or B can represent the following three cases: A exists alone; A and B exist simultaneously; B exists alone. Wherein, A and B can be singular or plural.

[0028] In the embodiments of the present application, the symbol " / " can represent that the associated objects before and after it are in an "or" relationship. In addition, the symbol " / " can also represent the division sign, that is, to perform division operation. For example, A / B can represent A divided by B.

[0029] The “at least one” or similar expressions in the embodiments of the present application refer to any combination of these items, including any combination of single or multiple items, refer to one or more, and multiple refers to two or more. For example, at least one of a, b or c can represent the following seven cases: a, b, c, a and b, a and c, b and c, a, b and c. Among them, each of a, b and c can be an element or a set containing one or more elements.

[0030] The “equal to” in the embodiments of the present application can be used with greater than, which is applicable to the technical solutions adopted when greater than, or can be used with less than, which is applicable to the technical solutions adopted when less than. When equal to is used with greater than, it is not used with less than; when equal to is used with less than, it is not used with greater than.

[0031] The existing power battery SOC calibration method is mostly limited to non-V2G scenarios. The mainstream SOC calibration method in the industry at present is to rely on 4S shop special equipment for complete charge and discharge cycle, or the owner himself to calibrate through self-charge and discharge.

[0032] The existing power battery SOC calibration scheme has the following defects: 4S shop calibration needs to send the vehicle to the designated place, and the single calibration time is 4-8 hours, and needs professional equipment, professional personnel operation and occupation of labor cost; In addition to time-consuming, the owner self-calibration is mostly based on shallow charging and discharging, can only correct local interval error, cannot solve the depth deviation, and cannot control the state information of the battery during charging and discharging; The idle rate of special equipment is high, the electric energy consumed in the calibration process is not realized in the coordinated use of power grid, and the resource utilization rate is low; Differentiation SOC calibration strategies cannot be performed for different battery types (such as ternary lithium battery, iron phosphate lithium battery). In addition, in the existing SOC calibration scheme based on charge and discharge cycle, the empty / full charging state data collected is easy to be affected by polarization interference or cell consistency difference, and then the correction reference of the SOC estimation algorithm is distorted, and it is difficult to realize high-precision calibration of SOC.

[0033] In view of the above problems, the embodiments of the present application provide a power battery SOC calibration method and system, which will be described in detail below in combination with the drawings.

[0034] Please refer to Figure 1 , Figure 1 is a system architecture diagram of a charge and discharge system provided by the embodiments of the present application, such as Figure 1As shown, the charge-discharge system 100 includes a first charge-discharge platform 110, a target vehicle 120, a user terminal 130, and a power grid 140. Among them, the first charge-discharge platform 110 includes a server 111 and a V2G charging pile 112, the target vehicle 120 includes a BMS system 121 and a power battery 122; the server 111 is connected with the V2G charging pile 112 and the user terminal 130 respectively, the V2G charging pile 112 is connected with the power grid 140 and the BMS system 121 respectively, the BMS system 121 is connected with the power battery 122, and the target vehicle 120 is further connected with the user terminal 130 in communication.

[0035] Among them, the server 111 is configured to receive and store various types of data on the BMS system 121, the V2G charging pile 112, the user terminal 130, and the power grid 140; and analyze the data and issue instructions to the V2G charging pile 112 to instruct the target vehicle 120 to perform a charge-discharge cycle; and obtain state data of the power battery 122 during the charge-discharge cycle transmitted by the V2G charging pile 112, and determine charge-discharge cycle data according to the state data; and further calibrate the SOC of the power battery 122 according to the charge-discharge cycle data; and feed back real-time information and SOC calibration report to the user terminal 130.

[0036] Among them, the V2G charging pile 112 is configured to receive the charge-discharge instructions issued by the server 111; and bidirectionally communicate with the BMS system 121 to realize control of the target vehicle 120 to complete a complete cycle of discharging, first static equalization, charging, and second static equalization, and obtain state data of the power battery 122, and then transmit the state data to the server 111; and bidirectionally communicate with the power grid 140 to realize bidirectional transmission of electric energy.

[0037] Among them, the BMS system 121 is configured to monitor the state of the power battery 122 in real time, and send the state data to the V2G charging pile 112; and receive instructions from the V2G charging pile 112 to dynamically adjust the battery working state.

[0038] Further, the user terminal 130 is an interactive entrance of the user and the system, such as a mobile phone, a tablet, a notebook computer, etc., and the user can check the vehicle charge-discharge progress, cost, and battery state through the user terminal 130. The power grid 140 is configured to provide electric energy to the V2G charging pile 112 or receive the power grid; and realize "peak load shifting" of the power grid 140, such as discharging the vehicle energy storage at the power consumption peak and charging the vehicle at the valley, to improve the stability of the power grid 140.

[0039] It can be seen that in the embodiment, the charging and discharging system 100 realizes a full-process closed loop from charging and discharging complete cycle control, data acquisition and analysis to SOC accurate calibration, which not only guarantees the safe and efficient charging and discharging of the power battery 122, but also realizes power grid load optimization through vehicle-to-grid interaction, and enables users to master the state in real time, thereby improving the intelligentization, accuracy and energy utilization efficiency of new energy vehicle charging and discharging management as a whole.

[0040] The application will be further described below Figure 2 The power battery SOC calibration method provided by the embodiment of the application will be further described.

[0041] Please refer to Figure 2 , Figure 2 is a step flowchart of a power battery SOC calibration method provided by the embodiment of the application, as Figure 2 shown, the method comprises the following steps:

[0042] In step S210, the target vehicle is controlled to be discharged to a V2G charging pile, and after the discharging is completed, the first stationary state is entered.

[0043] The discharging process is used to reduce the state of charge of the power battery to a low power interval (usually 5%-10%), to provide a low power scenario basis for subsequent collection of "empty state data", and to avoid the loss of low SOC interval reference in subsequent calibration due to high power.

[0044] The first stationary state after discharging is used to eliminate the electrochemical polarization and concentration polarization generated in the discharging process, for example, electrode surface charge accumulation, uneven distribution of electrolyte ions, to ensure that the voltage, capacity and other data collected subsequently can truly reflect the physical state of the battery, rather than "false data" disturbed by polarization.

[0045] In one possible embodiment, before the target vehicle is controlled to be discharged to the V2G charging pile, the method further comprises: acquiring initial state data of the power battery; determining that the power battery is in a calibration allowed state according to the initial state data; determining a charging and discharging strategy corresponding to the target vehicle and the V2G charging pile in this charging and discharging cycle according to the initial state data and current running state data of the V2G charging pile, the charging and discharging strategy comprising a first stationary duration corresponding to the first stationary state and a second stationary duration corresponding to the second stationary state.

[0046] The initial state data of the power battery comprises the current SOC of the power battery, the current temperature of the battery pack, the health state SOH of the battery cell, the consistency data of the battery cell, the battery type, the rated capacity, the highest and lowest voltages of the single battery cell, the V2G charging pile number currently connected by the vehicle, and other data reflecting the current state of the power battery.

[0047] The allowed calibration state refers to a specific state of the power battery that meets the "safety boundary" and "data validity condition" required for SOC calibration, and can support safe and accurate execution of the subsequent SOC calibration process. Specifically, the safety condition is used to ensure that the battery is safe during calibration, such as a temperature of 10-45°C, no short circuit, no overvoltage fault code, and a health state SOH of 70% or more; the validity condition is used to ensure that the collected calibration data has reference value, such as a current SOC of 30-80% and an initial cell voltage difference of 150 mV or less. For example, key indicators such as battery temperature, SOH, current SOC, cell voltage difference, and fault codes are extracted from the initial state data and compared with preset safety thresholds and validity thresholds to determine whether the power battery is in an allowed calibration state.

[0048] The charging and discharging strategy further includes an initial charging strategy and an initial discharging strategy. Specifically, the initial discharging strategy and the initial charging strategy can include charging and discharging SOC, charging and discharging power, and charging and discharging period. The charging and discharging period needs to be combined with the "current running state data" of the V2G charging pile, such as preferentially discharging during the power grid peak period (18:00-22:00) to increase energy feedback income, and preferentially charging during the power grid valley period (0:00-6:00) to reduce charging cost.

[0049] It should be noted that since the current state of the V2G charging pile and the target vehicle changes in real time, the charging and discharging strategy needs to be corrected based on the real-time acquired pile end and vehicle end state data to update the charging and discharging strategy in a timely manner.

[0050] Further, the charging and discharging strategy further includes a charging and discharging end condition. For example, the discharging end opportunity is any one of the following depth discharge termination conditions: any cell voltage reaches the discharging cutoff voltage; the SOC value reported by the BMS system of the target vehicle reaches a preset minimum safety value, such as 5% or 10%; and the total voltage of the battery pack reaches a preset minimum safety threshold. The present application does not limit the specific charging and discharging strategy.

[0051] Specifically, the control of the target vehicle to discharge to the V2G charging pile includes: sending a first discharging instruction to the BMS system of the target vehicle through the V2G charging pile, the first discharging instruction carrying an initial discharging strategy and a first static state time, the first discharging instruction being used to instruct the BMS system to control the power battery to discharge to the V2G charging pile according to the initial discharging strategy, and to enter the first static state and maintain the first static state time after discharging ends; receiving a first discharging completion instruction sent by the BMS system of the target vehicle and transmitted by the V2G charging pile, the first discharging completion instruction being used to instruct that the target vehicle has completed discharging and entered the first static state.

[0052] It can be understood that the V2G charging pile is connected with the BMS system of the target vehicle, the BMS system is used to monitor the current state of the power battery, and state data is transmitted to the V2G charging pile, and then transmitted to the server of the first charging and discharging platform via the sub-control module of the V2G charging pile.

[0053] It can be seen that in the embodiment, the pre-state verification customized charging and discharging strategy is executed, and the precise discharging and standing control is executed, which not only ensures the safety of the discharging process and the V2G scene adaptability, but also eliminates polarization through low-power discharging and the first standing, lays a foundation for subsequent collection of real and reliable emptying state data, and realizes the cooperation of calibration requirements and V2G energy management, and improves the safety, accuracy and scene applicability of the SOC calibration whole process.

[0054] In step S220, the emptying state data of the power battery is obtained, and the target vehicle is controlled to perform a first balancing operation according to the emptying state data, so that the voltage difference between any two cells in the power battery is less than a first preset threshold.

[0055] The emptying state data includes total battery voltage of the power battery after the first standing state ends, open circuit voltage of each cell, current SOC value, total discharging energy and the like.

[0056] In one possible embodiment, the first balancing operation is performed after the target vehicle passes through the first standing duration.

[0057] The first preset threshold can be a preset value set in advance by the user end, or a threshold dynamically determined by the server of the first charging and discharging platform or the BMS system of the target vehicle based on the real-time battery state of the power battery, or a threshold determined by the user end, the server or the BMS system. For example, the user end sets a basic threshold based on the battery type, such as a first preset threshold of 50mV for ternary lithium batteries and a first preset threshold of 30mV for iron phosphate batteries, which is a pre-determined industry general safety and accuracy standard; at the same time, the server or the BMS system will dynamically fine-tune in combination with the real-time battery state of the vehicle end, such as initial cell voltage difference, SOH, cycle number and the like. For example, when the battery SOH is lower than 80% (obviously aged), the basic threshold is relaxed by 5-10mV (to avoid frequent balancing damage to the battery), or when the initial voltage difference approaches the basic threshold, it is appropriately tightened by 2-3mV (to ensure better consistency after balancing).

[0058] In a possible embodiment, the controlling the target vehicle to perform the first balancing operation according to the emptying state data comprises: determining, according to the emptying state data, a plurality of open-circuit voltages corresponding to a plurality of battery cells in the power battery at the end of the first stationary state of the target vehicle; calculating a maximum voltage difference between any two battery cells according to the plurality of open-circuit voltages; determining whether the maximum voltage difference is greater than or equal to the first preset threshold; if yes, controlling the target vehicle to perform the first balancing operation on the power battery; and detecting that the voltage difference between any two battery cells is less than the first preset threshold.

[0059] It can be understood that after discharging, the battery cells may have different discharging degrees due to capacity attenuation and different internal resistances, resulting in excessive voltage difference between the battery cells. If the battery cells are not balanced, the inconsistent voltage data is directly used as the emptying state reference, which may cause the subsequent cycle data calculation and SOC calibration to lose accuracy, for example, the false electric quantity of the high-voltage battery cell is mistakenly regarded as the overall state of the battery. The first balancing operation can control the voltage difference between the battery cells within the threshold, so as to ensure that the collected emptying state data truly reflects the low electric quantity state of the overall battery, avoid calibration deviation caused by the difference in consistency of the battery cells, and serve as a key prerequisite for subsequent high-precision SOC calibration.

[0060] In a possible embodiment, the first balancing operation comprises the following steps: determining two battery cells with the maximum voltage difference greater than or equal to the first preset threshold; and determining a high-voltage battery cell in the two battery cells; and discharging the high-voltage battery cell through a resistor.

[0061] In the embodiment, the first balancing operation is performed on the power battery by the BMS system of the target vehicle. Specifically, the excess electric quantity of the high-voltage battery cell is consumed through the resistor, which belongs to a passive balancing mode, does not require a complex energy transfer circuit, has low cost and high reliability, and can avoid damage to the battery cell caused by rapid voltage drop by controlling the discharging current through the resistance value, such as slow discharging of small current.

[0062] Further, the operation duration of the first balancing operation is a first preset duration (for example, 8 hours). If the voltage balance between the plurality of battery cells cannot be achieved by performing the first balancing operation multiple times within the first preset duration after the end of the first stationary duration, the balancing operation is automatically exited after the end of the first preset duration, and an error is reported.

[0063] It should be noted that the embodiment of the present application only gives one way to balance the voltage between the plurality of battery cells, and does not limit other ways, for example, the voltage between the plurality of battery cells can also be balanced by a capacitor / capacitor energy transfer balancing, a DC-DC converter balancing, and the like.

[0064] It can be seen that, in the embodiment, by acquiring the polarization-eliminated emptying state data, the cell pressure difference is judged in combination with the first preset threshold, and then the cell pressure difference is controlled within the threshold, which not only ensures that the emptying state data can truly reflect the overall state of the battery in the low power state, but also avoids the subsequent calibration deviation caused by poor cell consistency, provides a reliable low power reference for high-precision SOC calibration, and takes into account the safety, low cost and adaptability of the balancing operation.

[0065] In step S230, the V2G charging pile is controlled to charge the target vehicle, and the target vehicle is controlled to enter a second stationary state after the charging is completed.

[0066] The charging process is used to charge the power battery from the "low power interval (5%-10%)" to the "high power interval (usually 95%-100%)", and to provide high power scene support for subsequent collection of "full charging state data". The BMS system records the voltage rising curve during the charging process, especially the saturation voltage in the high power section. It can be understood that only by covering the low and high power interval, the actual capacity, voltage characteristics and other key parameters of the battery can be calculated through the complete charging and discharging cycle data, and the problem of uneven accuracy in the full SOC range caused by traditional single-interval calibration is avoided.

[0067] After the charging is completed, the second stationary state is used to eliminate polarization through stationary state, so as to ensure that the full charging state data collected subsequently can truly reflect the physical state of the battery under high power, rather than "false high data" disturbed by polarization.

[0068] Specifically, the control of the V2G charging pile to charge the target vehicle includes: sending a first charging instruction to a sub-control module of the V2G charging pile, the first charging instruction carrying an initial charging strategy, the first charging instruction being used to instruct the V2G charging pile to charge the power battery of the target vehicle according to the initial charging strategy; receiving a first discharge completion instruction sent by the V2G charging pile, the first discharge completion instruction being used to instruct that the V2G charging pile has completed charging the target vehicle; sending a first stationary state instruction to the BMS system of the target vehicle through the V2G charging pile, the first stationary state instruction being used to instruct the power battery to enter the second stationary state and maintain the second stationary duration; receiving a first stationary state starting instruction sent by the BMS system of the target vehicle and transmitted by the V2G charging pile, the first stationary state starting instruction being used to instruct that the target vehicle has entered the second stationary state.

[0069] The initial charging strategy is a target charging strategy determined by the server based on the state data of the pile end and the vehicle end before the target vehicle is discharged, and dynamically corrected based on the real-time state data of the current power battery and the V2G charging station.

[0070] It can be seen that, in the embodiment, the V2G charging pile controls the battery to be charged from the low power to the full power interval through the initial charging strategy, and triggers the second static state to eliminate polarization after charging, which not only provides a high power reference for subsequent collection of real full charge state data and calculation of actual battery parameters, but also avoids the problem of uneven accuracy of traditional single interval calibration, and also adapts to the dynamic state of the vehicle and the pile through real-time correction strategy, and takes into account the calibration accuracy and the adaptability of the charging process in the V2G scenario.

[0071] In step S240, full charge state data of the power battery is obtained, and a second balancing operation is performed on the target vehicle according to the full charge state data, so that the voltage difference between any two cells in the power battery is less than a second preset threshold.

[0072] The full charge state data includes total battery voltage, open circuit voltage of each cell, current SOC value, total charging energy, real-time temperature of the battery pack, and the like of the power battery after the end of the second static state.

[0073] In one possible embodiment, the second balancing operation is performed after the target vehicle passes the second static duration.

[0074] The second preset threshold is consistent with the setting method of the first preset threshold.

[0075] In one possible embodiment, the second balancing operation is performed on the target vehicle according to the full charge state data, including: determining a plurality of open circuit voltages of a plurality of cells in the power battery of the target vehicle at the end of the second static state according to the full charge state data; calculating the maximum voltage difference between the any two cells according to the plurality of open circuit voltages; judging whether the maximum voltage difference is greater than or equal to the second preset threshold; if yes, controlling the target vehicle to perform the second balancing operation on the power battery; and detecting that the voltage difference between the any two cells is less than the second preset threshold.

[0076] It can be understood that after charging, the cells may have different charging acceptance capabilities (such as slow charging speed and fast voltage rise of aged cells), and the pressure difference may exceed the standard (such as some cells reaching the full charge voltage and some still not being fully charged). If the balancing is not performed, the "inconsistent high power data" is directly used as the reference, which may cause "full power false high" (such as mistakenly taking the state of the high voltage cell as the state of the whole battery) when estimating the SOC. Through the second balancing operation, the pressure difference is controlled within the second preset threshold, which can ensure that the full charge state data reflects the real state of the whole battery at high power, and forms a "full SOC range consistency reference" with the balancing data in the low power interval.

[0077] In one possible embodiment, the second equalization operation comprises the following steps: determining two battery cells whose maximum voltage difference is greater than or equal to the second preset threshold; and determining a high-voltage battery cell in the two battery cells; and discharging the high-voltage battery cell through a resistor.

[0078] The second equalization operation is performed by the BMS system of the target vehicle for the power battery. Specifically, the excess electricity of the high-voltage battery cell is consumed through a resistor, which belongs to a "passive equalization" mode, does not require a complex energy transfer circuit, has low cost and high reliability, and the discharge current is easy to control through the resistance value, such as slow discharge with small current, which can avoid damage to the battery cell due to rapid voltage drop.

[0079] Further, the operation duration corresponding to the second equalization operation is the second preset duration. If the voltage equalization between the plurality of battery cells cannot be achieved by executing the second equalization operation multiple times within the second preset duration after the end of the second static duration, the equalization operation is automatically exited after the end of the second preset duration, and an error is reported, and a maintenance warning report is generated and pushed to the user in the form of an APP and a screen display to remind the user to actively equalize and maintain the vehicle at a 4S store.

[0080] It should be noted that the embodiments of the present application only give one way to equalize the voltage between the plurality of battery cells, and do not limit other ways, for example, the voltage between the plurality of battery cells can also be equalized by a capacitor / capacitor energy transfer equalization, a DC-DC converter equalization, etc. In addition, the first equalization operation and the second equalization operation can be the same or different operations for equalizing the voltage between the plurality of battery cells.

[0081] It can be seen that, in the embodiments, the full charge state data after polarization elimination after the second static operation is collected, the second preset threshold is flexibly set to judge the voltage difference of the battery cell, the voltage difference is controlled within the threshold, and the timeout error reporting mechanism is used to ensure the reliability of the equalization, which not only ensures that the full charge state data truly reflects the overall state of the battery with high electricity, avoids calibration deviation caused by "full electricity false high", and forms a consistent reference in the full SOC range with low electricity equalization data, but also provides reliable high electricity support for high-precision SOC calibration, while considering the safety, adaptability and fault warning capability of the equalization operation.

[0082] In step S250, the initial state data, the empty state data, the full charge state data, the first equalization operation and the second equalization operation of the power battery are used to determine the current charge and discharge cycle data of the target vehicle.

[0083] The initial state data of the power battery, such as the initial SOC, the battery type and the SOH, is a "starting point basic data set" of the SOC calibration process, and the core role is to provide an initial basis for subsequent "judging whether calibration is possible", "developing a charge and discharge strategy" and "integrating charge and discharge cycle data", and is a front support to ensure calibration safety and accuracy.

[0084] The empty state data of the power battery is total voltage, open circuit voltage of each cell, current SOC, total discharge energy and the like after the power battery completes discharging and rests for a first resting duration.

[0085] The full charge state data of the power battery is total voltage, open circuit voltage of each cell, current SOC, total charge energy, battery pack temperature and the like after the power battery completes charging and rests for a second resting duration.

[0086] The first equalization operation is used to eliminate voltage difference of each cell after the power battery discharges and rests, so that the collected empty state data can truly reflect the overall low power state of the battery.

[0087] The second equalization operation is used to eliminate voltage difference of each cell after the power battery charges and rests, so as to ensure that the full charge state data can truly reflect the overall high power state of the battery.

[0088] It can be seen that, in the embodiment, by integrating the initial, empty and full charge three types of state data, and combining the correction effect of the two equalization operations, the current charge and discharge cycle data is constructed, which not only ensures that the data can truly reflect the charge and discharge characteristics of the battery in the full SOC range, but also provides complete and reliable core calculation basis for subsequent accurate calibration of SOC.

[0089] In step S260, the SOC of the power battery of the target vehicle is calibrated according to the charge and discharge cycle data.

[0090] It can be understood that the SOC is the "core ruler" of the whole vehicle energy management, and its accuracy directly determines three key functions: first, the prediction of the cruising range, and the inaccuracy of the SOC will lead to false cruising range or sudden decrease of the cruising range; second, the safety protection of the battery, and the misjudgment of the SOC may lead to overcharging and overdischarging, damage the battery and even cause safety risks; third, the life management of the battery, and the charge and discharge strategy based on the accurate SOC can reduce unnecessary cycle loss.

[0091] The traditional SOC calibration mainly depends on "static parameters" at the time of factory shipment, such as nominal capacity and fixed voltage-SOC curve, but the performance of the battery will change due to aging and increase of the cycle number in use, and the static parameters will gradually become invalid, thereby causing SOC deviation. Therefore, in the embodiment, the SOC is calibrated based on "current single charge and discharge cycle data" (reflecting the real-time state of the battery), rather than relying on historical fixed data, so that the SOC estimation can match the current performance of the battery in real time, solve the limitation of the traditional calibration "once and for all", and achieve the goal of "calibration with use, dynamic accuracy" of the battery management.

[0092] It can be seen that, in the embodiment, by controlling the target vehicle to complete the complete cycle of discharging, first stationary equalization, charging, and second stationary equalization in the V2G charging and discharging system, real charging and discharging data is obtained, and the voltage difference and polarization interference of the battery cells are eliminated through two stationary equalizations, so as to ensure the accuracy of the emptying and full charging state data. Based on the multi-dimensional state data and equalization operation information, charging and discharging cycle data is constructed, and finally the SOC of the power battery is accurately calibrated, and the SOC estimation accuracy is effectively improved.

[0093] The specific method for determining the vehicle charging and discharging cycle data and calibrating the SOC of the power battery based on the charging and discharging cycle data will be described below. Figures 3-4 The specific method for determining the vehicle charging and discharging cycle data and calibrating the SOC of the power battery based on the charging and discharging cycle data will be described below.

[0094] Specifically, refer to Figure 3 , Figure 3 is a flowchart for determining vehicle charging and discharging cycle data provided by the embodiment, and in terms of determining the current charging and discharging cycle data of the target vehicle based on the initial state data, emptying state data, full charging state data, first equalization operation and second equalization operation of the power battery, the above method further includes the following steps:

[0095] Step S310, extracting a first state data set of a plurality of battery cells in the power battery during the first equalization operation process and a second state data set of the plurality of battery cells in the power battery during the second equalization process.

[0096] The first state data set and the second state data set mainly include: real-time voltage change curve of each battery cell during equalization, equalization current, voltage difference between battery cells at different time nodes, equalization total time consumption, equalization energy consumption, capacity, etc.

[0097] Step S320, correcting the emptying state data based on the first state data set to obtain actual emptying data of the power battery in a stable emptying state; and correcting the full charging state data based on the second state data set to obtain actual full charging data of the power battery in a stable full charging state.

[0098] It can be understood that the emptying state data and the full charging state data are collected before equalization after static, and their reliability depends on whether the polarization is completely eliminated by static, that is, whether the "real stability" is reached. However, due to insufficient static duration or environmental influence, the polarization generated by discharging and charging may not be completely eliminated, such as electrode charge accumulation and uneven distribution of electrolyte ions, resulting in "false stable value" of voltage, energy, etc. (such as false high or false low voltage). If used directly, it will cause deviation in subsequent calculation based on these data, so it needs to be corrected based on the dynamic data in the equalization operation process.

[0099] In a possible embodiment, the correcting the emptying state data according to the first state data set to obtain actual emptying data of the power battery in a stable emptying state includes: determining a plurality of total battery voltages corresponding to a plurality of time nodes in the first equalization operation according to the first state data set; determining a standing stability judgment result corresponding to the emptying state data according to voltage fluctuation of the plurality of total battery voltages, the standing stability judgment result including a standing stable result and a standing unstable result, the standing stability judgment result being used to represent whether the emptying state data is true stable state data of the power battery corresponding to the first standing state; if it is judged that the standing stability judgment result is the standing stable result, correcting the emptying state data according to the first state data set to obtain the actual emptying data; if it is judged that the standing stability judgment result is the standing unstable result, calculating target emptying state data corresponding to the emptying state data after standing stabilization based on the first state data set; and correcting the target emptying state data according to the first state data set to obtain the actual emptying data.

[0100] The total battery voltages of the plurality of time nodes in the first equalization operation, such as total voltage values at 5 min, 15 min, 30 min and 60 min after the equalization starts, can reflect voltage response rules of the battery cell in the energy transfer and consumption process, such as whether to quickly tend to be stable or whether to exist abnormal fluctuation, and provide quantitative basis for subsequent judgment of standing stability.

[0101] Exemplarily, an example corresponding to the standing stable result is that if the total voltage fluctuation during the equalization is extremely small (such as a fluctuation of 30 min is less than or equal to 3 mV), and a deviation between a final stable value and the total voltage in the emptying state data is small (such as less than or equal to 5 mV), it is indicated that the first standing state has sufficiently eliminated polarization, the emptying state data is “true stable static data”, and only a difference in consistency of the battery cell exists. Therefore, it is necessary to calibrate and correct the emptying state data based on the battery data of the battery cell in the first state data set after equalization. For example, a maximum voltage difference of an original battery cell open circuit voltage in the emptying state data is 60 mV (before equalization), and the first state data set shows that the equalization is stable at 35 mV, then the equalization voltage of the battery cell is used to replace the corresponding value in the original data, and the total discharging energy is fine-tuned based on the equalization energy to obtain the actual emptying data.

[0102] The example corresponding to the standing instability result is: if the total voltage continues to decrease (e.g., decreases by ≥10 mV within 60 min) or fluctuates violently during the balancing, and the final value deviates greatly (e.g., >8 mV) from the empty state data, it indicates that the first standing state does not completely eliminate polarization, and the empty state data is a "false stable value", and there is battery polarization interference. Therefore, it is necessary to "make up for the lack of standing" first, and then correct the cell consistency deviation. For example, based on the change trend of the total voltage with the balancing time in the first state data set, such as fitting the voltage-time curve, the target empty state data after complete standing stability is calculated, such as extending the standing time according to the trend to completely eliminate polarization, to obtain the theoretical total voltage and cell voltage; then, the stable parameters after balancing in the first state data set are used to correct the target empty state data, to ensure that the polarization residual influence is eliminated and the consistency problem is solved, and finally the actual empty data is obtained.

[0103] It should be noted that the full charge state data of the power battery in the stable full charge state is corrected according to the second state data set, which can refer to the above-mentioned "correction of empty state data according to the first state data set" mode, and the same or different data processing mode is adopted.

[0104] It can be seen that in the embodiment, through dynamic data verification and scene-specific correction, the reliability of the original data is verified, and the polarization residual and the cell consistency deviation are eliminated, so that the final actual empty and full charge data can reflect the true physical characteristics of the battery without polarization interference, and can also reflect the consistency state after the cell balancing, thereby improving the reliability and accuracy of the data, and overcoming the problem of deviation caused by the "insufficient standing" or "cell consistency deviation" in the traditional method of directly using the static data after standing.

[0105] In step S330, the initial state data, the actual empty data and the actual full charge data are used to determine the target vehicle's this time's charge and discharge cycle data.

[0106] The this time's charge and discharge cycle data is a "core data set" integrating the key information of the whole calibration process, mainly including the following four types of core content, which can directly reflect the true charge and discharge characteristics of the battery: 1) the power and energy data, including the total energy / capacity of this time's discharge, the total energy / capacity of charging, and the change range of the initial SOC and the empty and full charge SOCs, which can be used to calculate the actual available capacity and energy loss of the battery; 2) the voltage characteristic data, covering the open circuit voltage at low power (after emptying) and high power (after full charging), and the voltage change curve during charging and discharging; 3) the balancing operation related data, including the cell voltage difference before and after the two times of balancing, the balancing energy consumption, the balancing time, etc., which are used to mark the cell consistency level; 4) the basic state data, such as the battery temperature and SOH in the calibration process, which are used to correct the influence of the environment and aging on the charge and discharge characteristics.

[0107] It can be seen that, in the embodiment, by integrating the low and high power stable data accurately corrected and the initial reference data, it is ensured that the charge and discharge cycle data can not only truly reflect the physical characteristics of the battery in the whole range, but also completely retain the key information of the calibration whole process, thereby providing a high-precision and full-dimension calculation basis for subsequent SOC calibration, and fundamentally improving the reliability of the calibration result.

[0108] Please refer to Figure 4 , Figure 4 is a flowchart provided by an embodiment of the present application for calibrating the SOC of a power battery based on charge and discharge cycle data. In terms of calibrating the SOC of a power battery of a target vehicle according to the charge and discharge cycle data, the above method further includes the following steps:

[0109] In step S410, the battery type of the power battery and the SOC estimation algorithm currently used by the power battery are determined.

[0110] Specifically, the voltage-SOC curve of the ternary lithium battery is a continuous slope, the energy density is high, but the low-temperature performance and cycle life are medium, and the capacity attenuation changes linearly with the cycle number; the lithium iron phosphate battery has a wide voltage platform, the voltage is not sensitive to the change of SOC, the safety is high, and the cycle life is long, but the energy density is slightly low, and the voltage is easy to deviate at low temperature; the voltage-SOC curve of the sodium ion battery has a weak platform region, the energy density and low-temperature performance are lower than those of the ternary lithium battery, and the capacity attenuation is obvious at low temperature.

[0111] Specifically, the ampere-hour integration method calculates the integral of the charge and discharge current and time (i.e., the electric quantity), combines the initial SOC, and calculates the current SOC. The advantage is high short-term accuracy, and the disadvantage is that the error is easy to accumulate over time; the open-circuit voltage method is based on the fixed correspondence between the open-circuit voltage and the SOC, and the SOC is obtained by measuring the open-circuit voltage after standing and looking up the table. The advantage is high long-term accuracy, and the disadvantage is that it needs to be static for a long time (cannot be estimated in real time), and the error is large in the voltage platform interval; the Kalman filter fusion algorithm fuses the ampere-hour integration method and the open-circuit voltage method, and corrects the error through algorithm iteration, taking into account the real-time and accuracy. The disadvantage is that the algorithm is complex and needs to be adapted to different battery characteristics. Generally, the ternary lithium battery preferentially uses the ampere-hour integration method or the open-circuit voltage method, the lithium iron phosphate battery preferentially uses the Kalman filter fusion algorithm, and the sodium ion battery preferentially uses the ampere-hour integration method.

[0112] In step S420, the SOC calibration index set corresponding to the power battery is determined according to the preset first association relationship and the battery type.

[0113] The first association relationship is used to represent a one-to-one correspondence relationship between the battery types of the plurality of power batteries and the plurality of SOC calibration index sets.

[0114] The SOC calibration index set includes a plurality of SOC calibration indexes.

[0115] Exemplarily, for a ternary lithium battery, the SOC calibration index set can include a full-charge voltage threshold, a discharge-charge voltage threshold, a charge-discharge coulomb efficiency, and voltage-SOC slope coefficients of different SOC intervals (0-20%, 20%-80%, and 80%-100%); and for a lithium iron phosphate battery, the SOC calibration index set can include a voltage platform starting point SOC value, a voltage platform ending point SOC value, a platform region voltage fluctuation tolerance (such as ±0.05V), and an OCV value corresponding to a capacity inflection point.

[0116] In step S430, a plurality of charge-discharge parameter values corresponding to the plurality of SOC calibration indexes are obtained from the charge-discharge cycle data.

[0117] In step S440, the SOC estimation algorithm is corrected according to the plurality of charge-discharge parameter values, so as to calibrate the SOC of the power battery of the target vehicle.

[0118] In one possible embodiment, the correction of the SOC estimation algorithm according to the plurality of charge-discharge parameter values includes: determining a target correction strategy corresponding to the SOC estimation algorithm according to a preset second association relationship, the second association relationship being used to represent a one-to-one correspondence relationship between a plurality of SOC estimation algorithms and a plurality of correction strategies; determining a plurality of core correction parameters according to the target correction strategy; extracting a plurality of target charge-discharge parameter values associated with the plurality of core correction parameters from the plurality of charge-discharge parameter values; and executing the target correction strategy according to the plurality of target charge-discharge parameter values.

[0119] It can be understood that the underlying logic and error sources of different SOC estimation algorithms are significantly different. For example, the ampere-hour integral method depends on the capacity parameter, and the open circuit voltage method depends on the voltage curve. If a unified correction method is used, it will lead to “incomplete correction” or “over-correction”. Therefore, it is necessary to match a dedicated correction path for each algorithm, and then focus on the core parameters to perform correction.

[0120] Exemplarily, the correction strategy corresponding to the ampere-hour integration method is to replace the theoretical parameters in the formula with the actual parameters of the charge and discharge cycle data, combine the dynamic charge and discharge efficiency curve to compensate for the loss, simultaneously calibrate the initial SOC, eliminate the integral cumulative error, and the corresponding core correction parameters include "actual available capacity", "charge and discharge efficiency coefficient", and "initial SOC calibration value"; the correction strategy corresponding to the open circuit voltage method is to extract the stable open circuit voltage of the key SOC node in the cycle data, reconstruct the voltage-SOC corresponding table, optimize the full charge and empty voltage threshold, adapt the actual static time, and correct the curve offset error, and the corresponding core correction parameters include "open circuit voltage value" and "full charge and empty voltage threshold".

[0121] It can be seen that, in the embodiment, by customizing the corresponding correction strategy for different SOC estimation algorithms, the actual parameters in the charge and discharge cycle data are used to dynamically update the core variables of the algorithm, which not only eliminates the error accumulation problem inherent in a single algorithm, but also improves the adaptability of the fusion algorithm through collaborative correction, and finally significantly reduces the deviation between the SOC estimation value and the actual state of the battery, effectively improving the SOC estimation accuracy.

[0122] Please refer to Figure 5 , Figure 5 is a whole flowchart of a power battery SOC calibration method provided by the embodiment of the present application, as shown in Figure 5The method comprises the following steps: in step S510, determining whether the initial state data of the power battery is in a state allowing calibration; if yes, executing step S520; in step S520, determining a charge-discharge strategy according to the initial state data of the power battery and the current operation state data of the V2G charging pile; in step S530, the target vehicle discharges to the V2G charging pile according to the charge-discharge strategy; in step S540, the target vehicle enters a first stationary state; in step S550, determining whether the maximum voltage difference between any two cells is greater than or equal to a first preset threshold based on the empty state data of the power battery; if yes, executing step S551; if no, executing step S552; in step S551, the target vehicle performs a first balancing operation; in step S552, the V2G charging pile charges the target vehicle according to the charge-discharge strategy; after step S551 is executed, the judgment operation of step S550 is repeatedly executed; in step S560, the target vehicle enters a second stationary state; in step S570, determining whether the maximum voltage difference between any two cells is greater than or equal to a second preset threshold based on the full charge state data of the power battery; if yes, executing step S571; if no, executing step S572; in step S571, the target vehicle performs a second balancing operation; in step S572, determining the current charge-discharge cycle data of the target vehicle according to the initial state data, the empty state data, the full charge state data, the first balancing operation and the second balancing operation of the power battery; after step S571 is executed, the judgment operation of step S570 is repeatedly executed; in step S580, calibrating the SOC of the power battery of the target vehicle according to the charge-discharge cycle data.

[0123] It can be seen that, in the embodiment, by controlling the target vehicle to complete the complete cycle of discharging, first stationary balancing, charging and second stationary balancing in the V2G charge-discharge system, real charge-discharge data is obtained, and the voltage difference and polarization interference of the cells are eliminated through two stationary balancing operations, so as to ensure the accuracy of the empty state data and the full charge state data; then, the charge-discharge cycle data is constructed based on the multi-dimensional state data and the balancing operation information, and finally the accurate calibration of the SOC of the power battery is realized, and the SOC estimation accuracy is effectively improved.

[0124] Please refer to Figure 6 , Figure 6 is an application scenario diagram of a power battery SOC calibration method provided by the embodiment of the application, as Figure 6 is shown, which presents the whole scene of the power battery SOC calibration method.

[0125] The BMS system of the target vehicle 120 monitors the battery state in real time and generates raw data, the V2G charging pile 112 serves as a hub, collects full-process parameters and uploads them to the server 111 while executing the charge-discharge and standing equalization cycle instructions; the server 111 extracts the SOC calibration index, corrects the algorithm and generates the result based on the charge-discharge cycle data, in combination with the battery type and SOC estimation algorithm characteristics; the user terminal 130 serves as an interactive portal, supports the user to initiate the calibration requirement and receive the calibration report; and the power grid 140 provides support for the charge-discharge cycle through energy supply and consumption, to ensure that the server 111 obtains effective data covering the full SOC range.

[0126] It can be seen that, in the embodiment, through the collaborative architecture of the vehicle BMS, the V2G charging pile, the server, the user terminal and the power grid, a closed loop of power battery SOC calibration from full-process data collection, algorithm dynamic correction to result feedback is realized, the SOC estimation accuracy is significantly improved, and a precise quantitative basis is provided for battery safety management, range prediction and vehicle-grid interaction efficiency.

[0127] Please refer to Figure 7 , Figure 7 A functional unit block diagram of a charge-discharge system provided in the embodiment of the application is shown in Figure 7 The charge-discharge system 100 includes the following units:

[0128] The first control unit 710 is configured to control the target vehicle to discharge to the V2G charging pile and enter a first standing state after the discharge is completed; obtain empty state data of the power battery, and control the target vehicle to perform a first equalization operation according to the empty state data, so that the voltage difference between any two cells in the power battery is less than a first preset threshold value.

[0129] The second control unit 720 is configured to control the V2G charging pile to charge the target vehicle, and control the target vehicle to enter a second standing state after the charge is completed; obtain full charge state data of the power battery, and control the target vehicle to perform a second equalization operation according to the full charge state data, so that the voltage difference between any two cells in the power battery is less than a second preset threshold value.

[0130] The processing unit 730 is configured to determine the current charge-discharge cycle data of the target vehicle according to the initial state data, the empty state data, the full charge state data, the first equalization operation and the second equalization operation of the power battery; and calibrate the power battery SOC of the target vehicle according to the charge-discharge cycle data.

[0131] In one embodiment, the determining the current charging and discharging cycle data of the target vehicle according to the initial state data of the power battery, the emptying state data, the full charging state data, the first equalization operation and the second equalization operation comprises: extracting a first state data set of a plurality of battery cells in the power battery in the first equalization operation process and a second state data set of a plurality of battery cells in the second equalization process; correcting the emptying state data according to the first state data set to obtain actual emptying data of the power battery in a stable emptying state; and correcting the full charging state data according to the second state data set to obtain actual full charging data of the power battery in a stable full charging state; and determining the current charging and discharging cycle data of the target vehicle according to the initial state data, the actual emptying data and the actual full charging data.

[0132] In one embodiment, the correcting the emptying state data according to the first state data set to obtain actual emptying data of the power battery in a stable emptying state comprises: determining a plurality of total battery voltages corresponding to a plurality of time nodes in the first equalization operation of the power battery according to the first state data set; determining a standing stability judgment result corresponding to the emptying state data according to voltage fluctuation of the plurality of total battery voltages, the standing stability judgment result comprising a standing stable result and a standing unstable result, the standing stability judgment result being used to represent whether the emptying state data is true stable state data corresponding to the power battery after the first standing state ends; if it is judged that the standing stability judgment result is the standing stable result, correcting the emptying state data according to the first state data set to obtain the actual emptying data; if it is judged that the standing stability judgment result is the standing unstable result, calculating target emptying state data corresponding to the emptying state data after standing stability based on the first state data set; and correcting the target emptying state data according to the first state data set to obtain the actual emptying data.

[0133] In an embodiment, the calibration of the SOC of the power battery of the target vehicle according to the charge-discharge cycle data comprises: determining a battery type of the power battery and a current SOC estimation algorithm adopted by the power battery; determining a corresponding SOC calibration index set of the power battery according to a preset first correlation and the battery type, the SOC calibration index set comprising a plurality of SOC calibration indexes, the first correlation representing a one-to-one correspondence between battery types of a plurality of power batteries and a plurality of SOC calibration index sets; obtaining a plurality of charge-discharge parameter values corresponding to the plurality of SOC calibration indexes from the charge-discharge cycle data; and modifying the SOC estimation algorithm according to the plurality of charge-discharge parameter values to realize the calibration of the SOC of the power battery of the target vehicle.

[0134] In an embodiment, the modification of the SOC estimation algorithm according to the plurality of charge-discharge parameter values comprises: determining a target modification strategy corresponding to the SOC estimation algorithm according to a preset second correlation, the second correlation representing a one-to-one correspondence between a plurality of SOC estimation algorithms and a plurality of modification strategies; determining a plurality of core modification parameters according to the target modification strategy; extracting a plurality of target charge-discharge parameter values associated with the plurality of core modification parameters from the plurality of charge-discharge parameter values; and executing the target modification strategy according to the plurality of target charge-discharge parameter values.

[0135] In an embodiment, the control of the target vehicle to perform the first balancing operation according to the emptying state data comprises: determining a plurality of open-circuit voltages corresponding to a plurality of battery cells in the power battery of the target vehicle at the end of the first stationary state according to the emptying state data; calculating a maximum voltage difference between any two battery cells according to the plurality of open-circuit voltages; determining whether the maximum voltage difference is greater than or equal to the first preset threshold; if yes, controlling the target vehicle to perform the first balancing operation on the power battery; and detecting that the voltage difference between any two battery cells is less than the first preset threshold.

[0136] In an embodiment, the first balancing operation and the second balancing operation comprise the following steps: determining two battery cells with the maximum voltage difference greater than or equal to the first preset threshold; determining a high-voltage battery cell in the two battery cells; and discharging the high-voltage battery cell through a resistor.

[0137] In an embodiment, before the control of the target vehicle to discharge to the V2G charging pile, the method further comprises: obtaining initial state data of the power battery; determining that the power battery is in an allowed calibration state according to the initial state data; determining a charging and discharging strategy corresponding to the current charging and discharging cycle of the target vehicle and the V2G charging pile according to the initial state data and current operation state data of the V2G charging pile, the charging and discharging strategy comprising a first static state corresponding first static duration and a second static state corresponding second static duration.

[0138] In an embodiment, the first balancing operation is performed after the target vehicle passes the first static duration, and the second balancing operation is performed after the target vehicle passes the second static duration.

[0139] It can be seen that, in the embodiment, by controlling the target vehicle to complete the complete cycle of discharging, first static balancing, charging, and second static balancing in the V2G charging and discharging system, real charging and discharging data is obtained, and the voltage difference and polarization interference of the battery cell are eliminated through two static balancing operations, so as to ensure the accuracy of the empty and full state data; and based on the multi-dimensional state data and the balancing operation information, the charging and discharging cycle data is constructed, and finally the precise calibration of the power battery SOC is realized, so as to effectively improve the SOC estimation accuracy.

[0140] Please refer to Figure 8 , Figure 8 is a structural block diagram of an electronic device provided by an embodiment of the present application, as shown in Figure 8 The electronic device 800 can include one or more of the following components: a processor 810, a memory 820 coupled to the processor 810, wherein the memory 820 can store one or more computer programs, and the one or more computer programs can be configured to be executed by the one or more processors 810 to implement the method described in the above embodiments.

[0141] The processor 810 can include one or more processing cores. The processor 810 connects various parts within the entire electronic device 800 with various interfaces and lines, performs various functions of the electronic device 800 and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory 820, and calling data stored in the memory 820. Alternatively, the processor 810 can be implemented in at least one of a hardware form of a digital signal processing (DSP), a field-programmable gate array (FPGA), a programmable logic array (PLA). The processor 810 can integrate a combination of one or several of a central processing unit (CPU), a graphics processor (GPU), and a modem, etc. Among them, the CPU mainly processes an operating system, a user interface, and an application program, etc.; the GPU is responsible for rendering and drawing display content; and the modem is used for processing wireless communication. It can be understood that the above-mentioned modem can also not be integrated into the processor 810, but be implemented by a separate communication chip.

[0142] The memory 820 can include a random access memory (RAM) and can also include a read-only memory (ROM). The memory 820 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 820 can include a program storage area and a data storage area, wherein the program storage area can store instructions for implementing an operating system, instructions for implementing at least one function (such as a touch function, a sound playing function, an image playing function, etc.), instructions for implementing the above-mentioned various method embodiments, etc. The data storage area can also store data created by the electronic device 800 in use, etc.

[0143] It can be understood that the electronic device 800 can include more or less structural elements than those in the above-mentioned structural block diagram, for example, a power module, a physical key, a Wi-Fi module, a speaker, a Bluetooth module, a sensor, etc., which are not limited herein.

[0144] In addition, the embodiment of the present application further provides a computer storage medium which stores a computer program capable of being loaded and executed by a processor, such as a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and the like.

[0145] It should be noted that, for each method embodiment described above, in order to simply describe, each method embodiment is described as a combination of a series of actions, but those skilled in the art should know that the present application is not limited by the action sequence described, because according to the present application, some steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily necessary for the present application.

[0146] In several embodiments provided in the present application, it should be understood that the disclosed methods, devices and systems can be implemented in other ways. For example, the device embodiments described above are only schematic; for example, the division of the units is only a logical function division, and actual implementation can have another division manner; for example, a plurality of units or components can be combined or integrated into another system, or some features can be omitted or not executed. In addition, the coupling or direct coupling or communication connection between the units or components shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0147] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. According to actual needs, some or all of the units can be selected to achieve the purpose of the embodiment.

[0148] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically included separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of hardware plus software functional unit.

[0149] The integrated unit in the form of software function unit can be stored in a computer readable storage medium. The software function unit is stored in a storage medium, and includes instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute part of steps of the method according to the embodiments of the present application. The storage medium includes a U disk, a mobile hard disk, a magnetic disk, an optical disk, a volatile memory or a non-volatile memory. The non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM) or a flash memory. The volatile memory can be a random access memory (RAM) used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) can be used, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synch link DRAM (SLDRAM) and direct rambus RAM (DRRAM), etc.

[0150] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0151] The embodiments of the present application are described in detail above, and the principle and implementation mode of the present application are described by applying specific examples; the above description of the embodiments is only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range can be changed; in conclusion, the content of the specification should not be understood as the limitation of the present application.

[0152] Although the present application has been disclosed with reference to the above examples, it is not intended to limit the present application. Any person skilled in the art, without departing from the spirit and scope of the present application, can easily think of changes or substitutions, and can make various changes and modifications, including combinations of different functions and implementation steps, including software and hardware implementations, all of which are within the scope of the present application.

Claims

1. A method for calibrating the SOC of a power battery, characterized in that, The application discloses a server applied to a first charging and discharging platform in a charging and discharging system, the first charging and discharging platform comprises a plurality of V2G charging piles, the charging and discharging system further comprises a target vehicle, the V2G charging pile is connected with the target vehicle, and the target vehicle comprises a power battery; the method comprises the following steps: controlling the target vehicle to perform discharging to the V2G charging pile and entering a first stationary state after the discharging is completed; obtaining empty state data of the power battery, and controlling the target vehicle to perform a first balancing operation according to the empty state data, so that the voltage difference between any two cells in the power battery is less than a first preset threshold value; controlling the V2G charging pile to perform charging to the target vehicle, and controlling the target vehicle to enter a second stationary state after the charging is completed; obtaining full charging state data of the power battery, and controlling the target vehicle to perform a second balancing operation according to the full charging state data, so that the voltage difference between any two cells in the power battery is less than a second preset threshold value; determining this time charging and discharging cycle data of the target vehicle according to initial state data of the power battery, the empty state data, the full charging state data, the first balancing operation and the second balancing operation; and calibrating the power battery SOC of the target vehicle according to the charging and discharging cycle data.

2. The method of claim 1, wherein, The method for determining the charging and discharging cycle data of the target vehicle according to the initial state data of the power battery, the empty state data, the full charging state data, the first balancing operation and the second balancing operation comprises the following steps: extracting a first state data set of a plurality of cells in the power battery in the first balancing operation process and a second state data set of a plurality of cells in the power battery in the second balancing process; correcting the empty state data according to the first state data set to obtain actual empty data of the power battery in a stable empty state, and correcting the full charging state data according to the second state data set to obtain actual full charging data of the power battery in a stable full charging state; determining the charging and discharging cycle data of the target vehicle according to the initial state data, the actual empty data and the actual full charging data.

3. The method of claim 2, wherein, The method for correcting the empty state data according to the first state data set to obtain the actual empty data of the power battery in the stable empty state comprises the following steps: determining a plurality of total battery voltages corresponding to a plurality of time nodes in the first balancing operation of the power battery according to the first state data set; determining a stationary stability judgment result corresponding to the empty state data according to the voltage fluctuation of the plurality of total battery voltages, the stationary stability judgment result comprising a stationary stable result and a stationary unstable result, and the stationary stability judgment result being used for representing whether the empty state data is true stable state data corresponding to the power battery after the first stationary state is ended; if it is judged that the stationary stability judgment result is the stationary stable result, correcting the empty state data according to the first state data set to obtain the actual empty data. If it is judged that the standing stability judgment result is the standing instability result, target emptying state data corresponding to the emptying state data after standing stability is calculated based on the first state data set, and the target emptying state data is corrected according to the first state data set to obtain the actual emptying data.

4. The method according to any one of claims 1 to 3, characterized in that, The calibration of the SOC of the power battery of the target vehicle according to the charge-discharge cycle data comprises: determining the battery type of the power battery and the SOC estimation algorithm currently adopted by the power battery; determining a SOC calibration index set corresponding to the power battery according to a preset first correlation and the battery type, the SOC calibration index set comprising a plurality of SOC calibration indexes, the first correlation being used to represent a one-to-one correspondence between the battery types of a plurality of power batteries and a plurality of SOC calibration index sets; obtaining a plurality of charge-discharge parameter values corresponding to the plurality of SOC calibration indexes from the charge-discharge cycle data; modifying the SOC estimation algorithm according to the plurality of charge-discharge parameter values to realize the calibration of the SOC of the power battery of the target vehicle.

5. The method of claim 4, wherein, The modification of the SOC estimation algorithm according to the plurality of charge-discharge parameter values comprises: determining a target modification strategy corresponding to the SOC estimation algorithm according to a preset second correlation, the second correlation being used to represent a one-to-one correspondence between a plurality of SOC estimation algorithms and a plurality of modification strategies; determining a plurality of core modification parameters according to the target modification strategy; extracting a plurality of target charge-discharge parameter values associated with the plurality of core modification parameters from the plurality of charge-discharge parameter values; executing the target modification strategy according to the plurality of target charge-discharge parameter values.

6. The method of claim 1, wherein, The control of the target vehicle to perform the first equalization operation according to the emptying state data comprises: determining a plurality of open-circuit voltages corresponding to a plurality of battery cells in the power battery of the target vehicle at the end of the first standing state according to the emptying state data; calculating the maximum voltage difference between any two battery cells according to the plurality of open-circuit voltages; judging whether the maximum voltage difference is greater than or equal to the first preset threshold value; if yes, controlling the target vehicle to perform the first equalization operation on the power battery.

7. The method of claim 6, wherein, The first equalization operation comprises the following steps: determining two battery cells whose maximum voltage difference is greater than or equal to the first preset threshold value, and determining a high-voltage battery cell in the two battery cells; discharging the high-voltage battery cell through a resistor.

8. The method of claim 1, wherein, Before the control of the target vehicle to discharge to the V2G charging pile, the method further comprises: obtaining initial state data of the power battery; judging that the power battery is in a calibration-allowed state according to the initial state data; determining a charge-discharge strategy corresponding to the target vehicle and the V2G charging pile in the current charge-discharge cycle according to the initial state data and current running state data of the V2G charging pile, the charge-discharge strategy comprising a first standing time corresponding to the first standing state and a second standing time corresponding to the second standing state.

9. The method of claim 8, wherein, The first equalization operation is performed after the target vehicle passes the first stationary duration, and the second equalization operation is performed after the target vehicle passes the second stationary duration.

10. A charge-discharge system characterized by comprising: The charging and discharging system comprises a first charging and discharging platform, the first charging and discharging platform comprises a plurality of V2G charging piles and a server, the charging and discharging system further comprises a target vehicle, the V2G charging piles are connected with the target vehicle, and the target vehicle comprises a power battery, wherein the server is used for performing the steps in the method according to any one of claims 1-9.

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