Method for calibrating SOC of energy storage battery

Abstract

The invention provides an energy storage battery SOC calibration method, relates to the field of storage battery calibration, and aims to solve the problems of long data acquisition period, high hardware cost, complex process, large calibration error and the like of an existing machine learning data driving type SOC estimation method based on a charging curve. The method provided by the invention comprises SOC calibration methods in charging and discharging processes, the charging process takes a current source controlled by current as a framework, charging is carried out through a direct-current power supply, and the battery charging amount is indirectly calculated by utilizing the electric quantity of a capacitor; in the discharging process, the battery charges the discharging capacitor, the discharging capacity is calculated according to the voltage of the capacitor, and the SOC is determined by combining the rated capacity of the battery. According to the method, the problems of complex calibration process and large data volume in the prior art are solved, the SOC calibration result of the battery can be more accurate, the calibration period of the energy storage battery can be determined according to the use condition and the performance change, and the timeliness of the calibration result is ensured.

Description

Technical Field

[0001] This invention relates to the field of battery calibration, and more specifically to a method for calibrating the state of charge (SOC) of an energy storage battery. Background Technology

[0002] Commonly used battery capacity calibration methods include the full charge-discharge method and the transient method. The full charge-discharge method involves fully charging the battery, then discharging it with a small current until the battery voltage reaches the calibration termination voltage. The battery capacity is then calculated based on the charging and discharging time and the integral of the current. The transient method involves applying a pulsed current to the battery, observing the change in battery voltage, and calculating the battery capacity based on the rate of change.

[0003] Existing machine learning-driven SOC (State of charge) estimation methods based on charging curves estimate the calibration through the following steps: S1. Charging Curve Acquisition: The energy storage system is charged using a constant current-constant voltage method, and parameters such as voltage, current, and temperature are recorded during the charging process. These data can be used to plot a charging curve for subsequent SOC estimation.

[0004] S2. Data Analysis: Based on the charging curve, extract key parameters, such as the voltage at the end of charging (voltage when SoC=100%) and the rate of voltage change during charging. These parameters will be used to build an SOC estimation model.

[0005] S3. SOC Model Establishment: Based on charging curve data, a SOC estimation model is established using mathematical methods (such as neural networks, linear regression, etc.). This model can be used to predict the SOC changes of the energy storage system during subsequent use.

[0006] S4. Model Validation: Verify the accuracy of the SOC model using actual measurement data. Typically, a certain percentage of battery capacity is reserved as validation data, and the error between the model's predicted values ​​and the actual measured values ​​is compared. If the error is within an acceptable range, the model validation is considered successful.

[0007] The constant current-constant voltage charging method described above needs to fully cover the entire process of the battery from low SOC to full charge. For large-capacity energy storage systems, a single data acquisition cycle requires 8-10 hours, which is extremely inefficient. Furthermore, it necessitates the deployment of high-precision sensors and data loggers, resulting in high hardware costs. This method requires extensive labeled data training, making it prone to getting trapped in local optima. Parameter tuning, such as the learning rate and the number of hidden layer nodes, relies heavily on human experience, requiring manual setting of thresholds or selection criteria. Subjective factors may introduce systematic errors. Therefore, this method is complex, involves a large amount of data, and yields significant errors in battery SOC calibration results. Summary of the Invention

[0008] To address the shortcomings of the existing technologies, the present invention aims to provide a method for SOC calibration of energy storage batteries, which solves the problems of complex SOC calibration processes and large data volumes, and provides more accurate SOC calibration results.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The present invention provides a SOC calibration method for energy storage batteries, including a SOC calibration method for batteries during charging based on a current source controlled by current (CCCS) as the basic framework, and a SOC calibration method for energy storage batteries during discharging, wherein the SOC is determined by comparing the calculation results of the charging and discharging process with the rated capacity of the battery.

[0010] In a preferred embodiment, the battery SOC calibration method during charging provided by this invention is characterized by comprising two main parts: a control part and a controlled part. The control part uses a DC power supply to charge the energy storage battery, with the charging current changing in real time according to the battery's capacity. As the battery approaches full capacity, the charging current gradually decreases. The controlled part uses a controlled current source to charge the capacitor during battery charging. After charging is complete, a voltmeter on the capacitor side measures the voltage across the capacitor. The charge amount during a complete charging process is calculated using the charging current and charging time. The charge amount during the charging process can be calculated using the capacitor's capacitance and the voltage across it. By calculating the amount of electricity stored in the capacitor, the charge amount during this battery calibration charging process can be indirectly calculated.

[0011] In a preferred embodiment, the battery SOC calibration method provided by the present invention during the discharge process is characterized in that, during the battery calibration discharge process, the discharge capacitor is discharged through a discharge resistor until the residual charge in the capacitor is completely discharged until the voltage across the capacitor is equalized. When the voltage is 0, the battery charges the discharge capacitor through the diode. Simultaneously, the Zener diode breaks down and operates at 2.6V. When the battery discharges to below 2.6V, the Zener diode stops working and the switch is disconnected. The voltage across the capacitor is measured, and the discharge amount during this process is calculated using the voltage across the capacitor and the capacitance value. The battery capacity measured during a single full charge and discharge cycle determines the calibration result. The calibration cycle for energy storage batteries is determined based on battery usage and performance changes to ensure the timeliness of the calibration results. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram illustrating the principle of SOC calibration during the charging process of the energy storage battery of the present invention; Figure 2This is a schematic diagram illustrating the principle of SOC calibration during the discharge process of the energy storage battery according to the present invention; Figure 3 This is a flowchart of the method for SOC calibration of energy storage batteries according to the present invention; Detailed Implementation The exemplary embodiments disclosed in this plan will be described below with reference to the accompanying drawings, including specific technical details disclosed in this plan to aid understanding. However, these details should be considered exemplary rather than restrictive. All other embodiments obtained by those skilled in the art based on the embodiments of this plan without inventive effort are within the scope of protection of this plan. The accompanying drawings only illustrate content related to this invention; parts not specifically stated in this specification are prior art.

[0013] With the development of artificial intelligence technology, its application in processing time-series data and extracting features has shown great potential. Machine learning is an important direction in the field of artificial intelligence technology. Applying machine learning to SOC estimation combines the advantages of model-driven and data-driven approaches, thereby improving the accuracy of SOC estimation. However, machine learning models rely on high-precision, noise-free charging curve data, and if the model is not trained on extreme operating condition data, estimation failures are likely to occur in practical applications.

[0014] In the field of battery calibration, accurate SOC calibration of energy storage batteries allows for the acquisition of precise battery capacity information. This enables the optimization of energy storage system operation strategies, improving overall system performance and reliability, and ensuring stable operation under various conditions. SOC calibration enables real-time monitoring of the battery's state of charge, preventing overcharging or over-discharging, which are major causes of battery damage and safety incidents. Therefore, accurate SOC calibration is crucial for ensuring battery safety. By monitoring and adjusting the battery's SOC in real time, the risk of battery safety incidents can be reduced.

[0015] Figure 1 The diagram below is a circuit diagram of a SOC calibration method applicable to the charging process of an energy storage battery according to an embodiment of the present invention. It should be noted that... Figure 1 The examples shown are merely examples of system architectures that can be applied to the embodiments of this disclosure, in order to help those skilled in the art understand the technical content of the present invention, but do not mean that the embodiments of the present invention cannot be used in other devices, system environments or scenarios.

[0016] like Figure 1As shown, this example illustrates the schematic diagram of SOC calibration during battery charging, based on a current source controlled by current. It mainly includes two parts: a control section and a controlled section. The control section uses a DC power supply to charge the energy storage battery. The charging current i1 changes in real time with the battery's charge level, gradually decreasing as the battery approaches full capacity. Before charging begins, the controlled section closes switch S2 to discharge any remaining charge in the charging capacitor through a discharge resistor until the voltage across the capacitor reaches zero. When the energy storage battery is charged, switch S1 is closed and switch S2 is open, and the controlled current source charges the capacitor. The charging current is 0. The magnitude of the charging current varies with The control coefficient changes with the change. The voltage across the capacitor is constant. The diode is used to prevent the capacitor from discharging. When the energy storage battery is fully charged, switch S1 is opened, and the voltmeter across the capacitor measures the voltage of the charging capacitor. .

[0017] The amount of charge in a complete charging process of an energy storage battery is shown in the following formula (4).

[0018] (4) The amount of charge on the capacitor during this charging process is shown in equation (5). (5) The capacitance of the capacitor It is known. It is measured using a voltmeter, and the amount of charge stored in the capacitor is calculated. This is used to indirectly calculate the amount of charge during this battery calibration charging process.

[0019] Figure 2 This is a circuit diagram of a SOC calibration method applicable to the discharge process of an energy storage battery according to an embodiment of the present invention.

[0020] like Figure 2 As shown, in this example, during the battery calibration discharge process, switch S4 is first closed and switch S3 is opened. The discharge capacitor is then discharged through the discharge resistor until the residual charge in the capacitor is completely discharged, until the voltage across the capacitor is equal to the discharge voltage. When the voltage is 0, during battery discharge, switch S4 is open and switch S3 is closed. The battery charges the discharge capacitor through the diode, and the Zener diode breaks down and operates at 2.6V. When the battery discharges to below 2.6V, the Zener diode stops working and switch S3 opens. At this time, the voltage across the capacitor is measured to be... The amount of discharge of the battery during this discharge process can be calculated as shown in the following formula (6).

[0021] (6) The battery's calibration result is determined by measuring its capacity during a single full charge and discharge cycle. The calibration cycle for energy storage batteries is determined based on battery usage and performance changes to ensure the timeliness of the calibration results.

[0022] Figure 3 This is a flowchart of a SOC calibration method for energy storage batteries according to an embodiment of the present invention.

[0023] like Figure 3 As shown, with the goal of SOC calibration of the energy storage battery, the process proceeds along two parallel main lines: charging and discharging. The left branch is for charging, and the right branch is for discharging. In the charging process, switch S2 is first closed and switch S1 is opened. To ensure data reliability, the charging capacitor is discharged until the voltage across it reaches zero. Once the voltage is fully discharged, S1 is closed and S2 is opened to mark the charging progress. After charging is complete, the charge amount is calculated based on the voltage across the charging capacitor. The discharging process is similar to the charging process. First, switch S4 is closed and switch S3 is opened to clear the voltage across the discharging capacitor to zero, preventing interference with the accuracy of subsequent calculations. After complete discharging, switch S3 is closed and switch S4 is opened. The battery charges the discharging capacitor through a diode. The Zener diode is broken down and operates at 2.6V. When the battery discharges to below 2.6V, the Zener diode stops working, and switch S3 is opened, completing the discharging process. At this point, the voltage across the capacitor is measured, and the discharge amount is calculated. Based on the battery capacity measured after a series of calculations of charging and discharging amounts, the ratio of the battery capacity to the battery's rated capacity is used to obtain the accurate SOC calibration result.

[0024] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for SOC calibration of an energy storage battery, characterized in that: Includes the following steps: S1. Perform the charging process and obtain battery charging process data in the charging circuit. S2. Perform the discharge process and obtain battery discharge process data in the discharge circuit; S3. The battery SOC is calibrated by calculating the charge and discharge amounts.

2. The method for SOC calibration of an energy storage battery according to claim 1, characterized in that, In step S1: the charging process parameters include the charging current of the control section, the current of the controlled section, and the voltage across the charging capacitor; Control section charging current As the battery level changes in real time; The controlled current source charges the capacitor, and the charging current of the controlled part is... The magnitude of the charging current varies with The control coefficient changes with the change. Constant and unchanging; When the energy storage battery is fully charged, the voltmeter across the capacitor measures the voltage across the capacitor. .

3. The method for SOC calibration of an energy storage battery according to claim 2, characterized in that, The amount of charge the battery receives during the entire charging process From charging current and charging time The calculation results are shown in equation (1): (1)； The amount of charge on the charging capacitor during the charging process As shown in equation (2): (2)； Among them, the capacitance of the capacitor It is known. It was measured using a voltmeter. Control coefficient for battery charging amount Constant and unchanging.

4. The method for SOC calibration of an energy storage battery according to claim 1, characterized in that, in step S2: the discharge process parameters include the breakdown voltage of the Zener diode and the voltage across the discharge capacitor; The breakdown voltage of the Zener diode is 2.6V. When the battery discharges to a remaining voltage below 2.6V, the Zener diode stops working. The voltage across the discharge capacitor is This is used to calculate the amount of discharge during this battery discharge process.

5. The method for SOC calibration of an energy storage battery according to claim 4, characterized in that, The battery charges the discharge capacitor through the diode, while the Zener diode breaks down and operates at 2.6V. The discharge amount during the discharge process can be seen from the following formula (3): (3)； Among them, the capacitance of the capacitor It is known. It was measured using a voltmeter.

6. The method for SOC calibration of an energy storage battery according to claim 1, characterized in that, In step S3: The battery SOC is calibrated using the calculated charge and discharge amounts; With the goal of SOC calibration of energy storage batteries, the process is being advanced through two parallel main lines: charging and discharging.

7. The method for SOC calibration of an energy storage battery according to claim 6, characterized in that, include: SOC calibration circuit during energy storage battery charging; In the charging process, switch S2 is closed and switch S1 is opened first. To ensure data reliability, the charging capacitor is discharged until the voltage on both sides is 0. When the voltage on both sides has been fully discharged, switch S1 is closed and switch S2 is opened to mark the charging process. After the charging is completed, the amount of charging is calculated based on the voltage on both sides of the charging capacitor.

8. The method for SOC calibration of an energy storage battery according to claim 6, characterized in that, include: SOC calibration circuit during the discharge process of energy storage battery; The discharge process involves first closing switch S4 and opening switch S3 to reset the voltage across the discharge capacitor to zero, preventing interference with the accuracy of subsequent calculations. After complete discharge, switch S3 is closed and switch S4 is opened, allowing the battery to charge the discharge capacitor through a diode. The Zener diode operates at 2.6V due to breakdown. When the battery discharges to below 2.6V, the Zener diode stops working and switch S3 is opened, completing the discharge process. At this point, the voltage across the capacitor is measured, and the discharge amount is calculated.

9. The method for SOC calibration of an energy storage battery according to claim 6, characterized in that, The battery capacity is determined by measuring the charge and discharge amounts during a full charge and discharge cycle, thereby determining the battery's SOC calibration result. The calibration cycle of energy storage batteries is determined based on the battery's usage and performance changes to ensure the timeliness of the calibration results.

10. A battery calibration device, characterized in that, The device includes a storage battery and a SOC calibration method for an energy storage battery according to any one of claims 1-9 for calibrating the storage battery.

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