Sodium ion energy storage soc dynamic equalization and calibration method combined with carrier phase shift modulation

Abstract

The application provides a sodium ion energy storage SOC dynamic balancing and calibration method combined with carrier phase modulation, after a SOC acquisition module collects voltage, current and temperature data of a sodium ion battery, a main control unit calculates an SOC value and constructs a global SOC deviation index, when the SOC deviation index is greater than a preset threshold, the main control unit sends a phase shift angle update instruction to a carrier phase modulation module, so that the sodium ion battery with a larger SOC deviation preferentially participates in the balancing process, meanwhile, the carrier phase modulation module transfers the energy of the sodium ion battery with a higher SOC to the sodium ion battery with a lower SOC, after completing the balancing process once, the calculation of the SOC value and the global SOC deviation index is performed again, until the global SOC deviation index is less than the preset threshold, by introducing the carrier phase modulation technology, the problem of battery pack performance decline caused by SOC imbalance in the traditional method is solved, and by optimizing the system parameters through the genetic algorithm, the efficiency and accuracy of the balancing process are improved.

Description

Technical Field

[0001] This invention relates to the field of power electronic control technology, and in particular to a method for dynamic equalization and calibration of sodium ion energy storage SOC combined with carrier phase shift modulation. Background Technology

[0002] In recent years, the rapid development of energy storage technology has brought about significant changes in the energy sector. Sodium-ion batteries, due to their abundant resources, low cost, and environmental friendliness, have gradually become an important research direction in the field of large-scale energy storage. However, in practical applications, existing sodium-ion energy storage systems still have certain limitations in the dynamic balancing and calibration of the state of charge (SOC) of individual battery cells, which to some extent affects the overall performance and reliability of the system.

[0003] A search revealed an energy storage system with publication number CN116487766B. This patent utilizes a direct connection between a liquid-cooled plate and a liquid-cooled unit, eliminating the need for traditional liquid-cooled branch and main pipelines, thereby increasing the energy density of the energy storage system and optimizing heat dissipation performance. However, this technical solution primarily focuses on the physical structure design and heat dissipation efficiency improvement of the energy storage system, neglecting the dynamic balancing and calibration of individual battery cell SOCs. This lack of effective management of individual battery cell SOC differences may lead to imbalances in the battery pack during long-term operation, consequently affecting the lifespan and safety of the energy storage system.

[0004] Furthermore, a storage device with publication number CN118398997B is also disclosed. This patent uses a short-circuit detection unit to achieve address identification of the battery pack, thereby improving the communication reliability and maintainability of the energy storage device. However, this technical solution focuses on the physical connection and communication functions of the battery pack and does not involve specific methods for dynamic SOC balancing of individual battery cells. At the same time, this solution does not mention how to utilize advanced modulation techniques (such as carrier phase-shift modulation) to achieve dynamic SOC calibration, which may lead to insufficient adaptability and stability of the system under complex operating conditions.

[0005] The above problems indicate that existing sodium-ion energy storage systems still have certain shortcomings in terms of dynamic equalization and calibration of cell SOC, especially in achieving efficient equalization and calibration by combining advanced modulation technology, which has not yet been fully resolved. Summary of the Invention

[0006] In view of this, the present invention proposes a dynamic equalization and calibration method for sodium-ion energy storage SOC that combines carrier phase-shift modulation. By introducing carrier phase-shift modulation technology, the dynamic equalization and calibration process of sodium-ion battery SOC is optimized, thereby improving the overall performance, reliability and service life of the energy storage system, and thus meeting the demand for efficient and intelligent energy storage systems in the field of large-scale energy storage.

[0007] The technical solution of this invention is implemented as follows:

[0008] A dynamic equalization and calibration method for sodium-ion energy storage (SOC) based on carrier phase-shift modulation is proposed, comprising a carrier phase-shift modulation module, an SOC acquisition module, an equalization control module, a main control unit, and a CAN bus. The carrier phase-shift modulation module consists of several parallel power converters. The steps of the equalization and calibration method are as follows:

[0009] Step S1: Connect each power converter to a corresponding sodium-ion battery, and coordinate the control of several power converters through phase shift angle;

[0010] Step S2: Collect the voltage, current and temperature data of each sodium-ion battery in real time through the SOC acquisition module, and calculate the SOC value of the sodium-ion battery based on the ampere-hour integration method.

[0011] Step S3: Construct a global SOC deviation index based on the SOC value of sodium-ion batteries;

[0012] Step S4: Update the phase shift angle of each power converter based on the global SOC deviation index;

[0013] Step S5: Transfer the energy from the sodium-ion battery with a higher SOC to the sodium-ion battery with a lower SOC through the carrier phase-shift modulation module;

[0014] Step S6: After completing one equalization operation, recalculate the SOC value of each sodium-ion battery and update the global SOC deviation index. When the global SOC deviation index is less than the preset threshold, stop the equalization operation; otherwise, return to step S4.

[0015] Step S7: Based on historical operating data, a genetic algorithm is used to optimize the system with the goal of minimizing the global SOC deviation index.

[0016] Step S8: Integrate the carrier phase-shift modulation module, SOC acquisition module, equalization control module, and main control unit into the sodium ion energy storage system, and connect the main control unit to the carrier phase-shift modulation module, SOC acquisition module, and equalization control module via CAN bus.

[0017] Preferably, the initial phase shift angles of the plurality of power converters in step S1 are:

[0018] ;

[0019] in, N The number of sodium-ion batteries is determined, and the phase shift angle is adjusted via a PWM signal issued by the main control unit.

[0020] Preferably, the formula for calculating the SOC value of the sodium-ion battery in step S2 is as follows:

[0021] ;

[0022] in, Let be the SOC value of the i-th sodium-ion battery at time t. The initial SOC value, This refers to the nominal capacity of a sodium-ion battery. Let be the current of the i-th sodium-ion battery.

[0023] Preferably, the specific steps of step S3 are as follows:

[0024] Based on the SOC value of sodium-ion batteries, an SOC deviation matrix is ​​constructed, whose elements are... Indicates the first i The sodium-ion battery and the first j The SOC difference between individual sodium-ion batteries is calculated using the following formula:

[0025] ;

[0026] Define the global SOC deviation index The root mean square value of the SOC difference for all sodium-ion batteries is given by the following formula:

[0027] ;

[0028] Where N represents the number of sodium-ion batteries. , The first i The, the j The SOC value of a sodium-ion battery.

[0029] Preferably, the formula for adjusting the phase shift angle of each power converter in step S4 is:

[0030] ;

[0031] in For the first i The power converter in the first Phase shift angle in the next iteration and These are the proportional and integral coefficients, respectively.

[0032] Preferably, the formula for the amount of energy transferred in step S5 is:

[0033] ;

[0034] in Energy transfer amount and These are the sodium-ion batteries with the highest and lowest SOC, respectively. This represents the maximum amount of energy that can be transferred in a single equilibration operation.

[0035] Preferably, the specific steps of step S7 are as follows:

[0036] Based on historical operational data, a genetic algorithm was used to adjust the proportional coefficient. Integral coefficient and maximum energy transfer The optimization objective is to minimize the global SOC deviation index. Its formula is:

[0037] ;

[0038] The constraints on the objective function include the voltage range, current limit, and temperature rise limit of the sodium-ion battery.

[0039] Preferably, the control signal output terminal of the carrier phase-shift modulation module is connected to the circuit board of the sodium-ion battery, the control signal input terminal of the carrier phase-shift modulation module is connected to the control signal output terminal of the main control unit via a CAN bus, the SOC acquisition module is connected to the monitoring terminal of the sodium-ion energy storage system, the signal output terminal of the SOC acquisition module is connected to the signal input terminal of the main control unit, the equalization control module is integrated on the equalization control board of the sodium-ion energy storage system and is directly connected to the carrier phase-shift modulation module via a signal line, and the control signal input terminal of the equalization control module is connected to the control signal output terminal of the main control unit.

[0040] Preferably, the power converter includes a high-frequency switching device, which is connected to the main control unit through a drive circuit. The SOC acquisition module includes a high-precision sensor and a data processing circuit. The high-precision sensor is installed near the positive and negative terminals of each sodium-ion battery and includes a voltage sensor, a current sensor, and a temperature sensor. The data processing circuit includes an analog signal conditioning circuit and an analog-to-digital converter. The analog signal conditioning circuit converts the data acquired by the high-precision sensor into a standard electrical signal and then sends it to the analog-to-digital converter for digital processing. The digitized data is transmitted to the main control unit through the SPI bus.

[0041] Preferably, the equalization control module includes a microcontroller, which communicates with the main control unit via an I2C bus;

[0042] The main control unit includes a high-performance processor used to calculate the SOC value of the sodium-ion battery, adjust the phase shift angle of each power converter, and optimize the genetic algorithm.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] Compared to existing technologies, this invention solves the problem of battery pack performance degradation caused by SOC imbalance in traditional methods by introducing carrier phase-shift modulation technology. By combining the phase shift angle of the power converter with the SOC deviation matrix, it achieves precise energy distribution among sodium-ion batteries, avoiding the limitations of single physical structure design or communication function optimization. In addition, through mathematical modeling and algorithm design, a global SOC deviation index is established. This provides a quantitative basis for the balancing process, further improving the system's reliability and intelligence level. It can adapt to the operational needs under complex working conditions, demonstrating strong stability and adaptability, and providing an efficient and intelligent solution for the field of large-scale energy storage.

[0045] On the other hand, this invention expands the application scope of carrier phase-shift modulation technology, making it a core tool for dynamic SOC balancing and calibration in energy storage systems. By optimizing system parameters through genetic algorithms, the efficiency and accuracy of the balancing process are improved, providing theoretical support for the intelligent management of energy storage systems. In practical applications, high-precision sensors and real-time data processing significantly improve the performance consistency of battery packs, extend their service life, and reduce safety risks caused by SOC imbalance. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 The flowchart shows the sodium ion energy storage SOC dynamic equalization and calibration method combined with carrier phase shift modulation of the present invention.

[0048] Figure 2 This is a schematic diagram showing the connection principle of each module in the sodium ion energy storage SOC dynamic equalization and calibration method combined with carrier phase shift modulation of the present invention.

[0049] In the diagram, 1 is the carrier phase-shift modulation module; 2 is the SOC acquisition module; 3 is the equalization control module; 4 is the main control unit; and 5 is the CAN bus. Detailed Implementation

[0050] To better understand the technical content of this invention, a specific embodiment is provided below, and the invention will be further described in conjunction with the accompanying drawings.

[0051] See Figures 1 to 2The present invention provides a method for dynamic equalization and calibration of sodium-ion energy storage (SOC) based on carrier phase-shift modulation, comprising a carrier phase-shift modulation module 1, an SOC acquisition module 2, an equalization control module 3, a main control unit 4, and a CAN bus 5. The carrier phase-shift modulation module 1 is composed of several parallel power converters. The steps of the equalization and calibration method are as follows:

[0052] Step S1: Connect each power converter to a corresponding sodium-ion battery, and coordinate the control of several power converters through phase shift angle;

[0053] Step S2: Collect the voltage, current and temperature data of each sodium-ion battery in real time through the SOC acquisition module 2, and calculate the SOC value of the sodium-ion battery based on the ampere-hour integration method.

[0054] Step S3: Construct a global SOC deviation index based on the SOC value of sodium-ion batteries;

[0055] Step S4: Update the phase shift angle of each power converter based on the global SOC deviation index;

[0056] Step S5: Transfer the energy from the sodium-ion battery with a higher SOC to the sodium-ion battery with a lower SOC through the carrier phase-shifting modulation module 1;

[0057] Step S6: After completing one equalization operation, recalculate the SOC value of each sodium-ion battery and update the global SOC deviation index. When the global SOC deviation index is less than the preset threshold, stop the equalization operation; otherwise, return to step S4.

[0058] Step S7: Based on historical operating data, a genetic algorithm is used to optimize the system with the goal of minimizing the global SOC deviation index.

[0059] Step S8: Integrate the carrier phase shift modulation module 1, SOC acquisition module 2, equalization control module 3 and main control unit 4 into the sodium ion energy storage system, and connect the main control unit 4 to the carrier phase shift modulation module 1, SOC acquisition module 2 and equalization control module 3 via CAN bus 5.

[0060] This invention discloses a dynamic SOC equalization and calibration method for sodium-ion energy storage combining carrier phase-shift modulation, applied to a corresponding equalization and calibration system. The equalization and calibration system comprises a carrier phase-shift modulation module 1, a SOC acquisition module 2, an equalization control module 3, a main control unit 4, and a CAN bus 5. Each power converter in the carrier phase-shift modulation module 1 is connected to a sodium-ion battery. Different power converters are coordinated and controlled through phase shift angles. Before equalization and calibration, the voltage, current, and temperature data of the sodium-ion batteries are acquired by the SOC acquisition module 2 and transmitted to the main control unit 4. The main control unit 4 calculates the SOC value of each sodium-ion battery and constructs a global SOC deviation index based on the calculation structure of the sodium-ion battery's SOC value. When the global SOC deviation index exceeds a preset threshold, the main control unit 4 generates a corresponding phase shift angle update command and sends it to the carrier phase-shift modulation module 1 via the CAN bus 5. Simultaneously, it sends an equalization start command to the equalization control module 3, initiating carrier phase shift. The modulation module 1 adjusts the phase angle of each power converter according to the received phase angle update command, so that sodium-ion batteries with larger SOC deviations participate in the equalization process first. The equalization start command can be sent to the power converter in the carrier phase shift modulation module 1 to perform energy transfer operation. After completing one equalization operation, the SOC acquisition module 2 re-acquires the voltage, current and temperature data of each sodium-ion battery and recalculates the SOC value. The main control unit 4 recalculates the global SOC deviation index according to the new SOC value. When the global SOC deviation index is less than the preset threshold, the main control unit 4 stops the equalization operation; otherwise, it returns to step S4 to readjust the phase angle. In addition, the main control unit 4 also optimizes the process using a genetic algorithm, with the optimization goal of minimizing the global SOC deviation index. By introducing carrier phase shift modulation technology, the dynamic equalization and calibration process of sodium-ion battery SOC is optimized, improving the overall performance, reliability and service life of the energy storage system, thereby meeting the needs of large-scale energy storage fields for efficient and intelligent energy storage systems.

[0061] Preferably, the initial phase shift angles of the plurality of power converters in step S1 are:

[0062] ;

[0063] in, N The number of sodium-ion batteries is adjusted by the PWM signal issued by the main control unit 4. The PWM signal is isolated and amplified before being input to the drive circuit of the power converter, thereby changing the output characteristics of the power converter to achieve precise energy distribution.

[0064] Preferably, the formula for calculating the SOC value of the sodium-ion battery in step S2 is as follows:

[0065] ;

[0066] in, Let be the SOC value of the i-th sodium-ion battery at time t. The initial SOC value, This refers to the nominal capacity of a sodium-ion battery. The calculated SOC value, representing the current of the i-th sodium-ion battery, is transmitted to the main control unit 4 via CAN bus 5.

[0067] Preferably, the specific steps of step S3 are as follows:

[0068] Based on the SOC value of sodium-ion batteries, an SOC deviation matrix is ​​constructed, whose elements are... Indicates the first i The sodium-ion battery and the first j The SOC difference between individual sodium-ion batteries is calculated using the following formula:

[0069] ;

[0070] Define the global SOC deviation index The root mean square value of the SOC difference for all sodium-ion batteries is given by the following formula:

[0071] ;

[0072] Where N represents the number of sodium-ion batteries. , The first i The, the j The SOC value of a sodium-ion battery.

[0073] The main control unit 4 constructs the SOC deviation matrix D based on the calculated SOC value. The elements of the SOC deviation matrix D are: Then, the main control unit 4 defines the global SOC deviation index as the root mean square value of the SOC difference of all sodium-ion batteries based on the SOC deviation matrix D.

[0074] Preferably, the formula for adjusting the phase shift angle of each power converter in step S4 is:

[0075] ;

[0076] in For the first i The power converter in the first Phase shift angle in the next iteration and These are the proportional and integral coefficients, respectively.

[0077] When the global SOC deviation exceeds the preset threshold, the main control unit 4 generates a phase shift angle update command and sends it to the carrier phase shift modulation module 1 via the CAN bus 5. The carrier phase shift modulation module 1 adjusts the phase shift angle of each power converter according to the received phase shift angle update command, so that the sodium-ion batteries with larger SOC deviations participate in the equalization process first.

[0078] Preferably, the formula for the amount of energy transferred in step S5 is:

[0079] ;

[0080] in Energy transfer amount and These are the sodium-ion batteries with the highest and lowest SOC, respectively. This represents the maximum amount of energy that can be transferred in a single equilibration operation.

[0081] The equalization control module 3 generates specific equalization quality according to the equalization start command of the main control unit 4, and sends it to the power converter in the carrier phase shift modulation module 1 to perform energy transfer operation.

[0082] Preferably, the specific steps of step S7 are as follows:

[0083] Based on historical operational data, a genetic algorithm was used to adjust the proportional coefficient. Integral coefficient and maximum energy transfer The optimization objective is to minimize the global SOC deviation index. Its formula is:

[0084] ;

[0085] The constraints on the objective function include the voltage range, current limit, and temperature rise limit of the sodium-ion battery.

[0086] After multiple iterations, the SOC values ​​of all sodium-ion batteries gradually converged, eventually reaching an equilibrium state.

[0087] Preferably, the control signal output terminal of the carrier phase-shift modulation module 1 is connected to the circuit board of the sodium-ion battery, the control signal input terminal of the carrier phase-shift modulation module 1 is connected to the control signal output terminal of the main control unit 4 via a CAN bus 5, the SOC acquisition module 2 is connected to the monitoring terminal of the sodium-ion energy storage system, the signal output terminal of the SOC acquisition module 2 is connected to the signal input terminal of the main control unit 4, the equalization control module 3 is integrated on the equalization control board of the sodium-ion energy storage system and is directly connected to the carrier phase-shift modulation module 1 via a signal line, and the control signal input terminal of the equalization control module 3 is connected to the control signal output terminal of the main control unit 4.

[0088] SOC acquisition module 2 collects voltage, current, and temperature data from sodium-ion batteries. Then, main control unit 4 calculates the SOC value of the sodium-ion batteries and constructs a global SOC deviation index based on these values. When the global SOC deviation index exceeds a preset threshold, main control unit 4 generates a phase shift angle update command and transmits it to carrier phase shift modulation module 1 via CAN bus 5. Carrier phase shift modulation module 1 updates the phase shift angle of each power converter, prioritizing sodium-ion batteries with larger SOC deviations for the equalization process. Equalization control module 3 receives the equalization start command from main control unit 4, generates specific equalization commands, and sends them to the power converters in carrier phase shift modulation module 1 to perform energy transfer operations. After completing one equalization operation, SOC acquisition module 2 re-acquires voltage, current, and temperature data. Main control unit 4 calculates the SOC value of each sodium-ion battery, updates the global SOC deviation index, and compares it with a preset threshold. If the value is less than the threshold, the equalization process stops. Simultaneously, main control unit 4 can optimize some parameters based on historical data using a genetic algorithm. The objective function of the genetic algorithm is to minimize the global SOC deviation.

[0089] Preferably, the power converter includes a high-frequency switching device, which is connected to the main control unit 4 via a drive circuit. The SOC acquisition module 2 includes a high-precision sensor and a data processing circuit. The high-precision sensor is installed near the positive and negative terminals of each sodium-ion battery and includes a voltage sensor, a current sensor, and a temperature sensor. The data processing circuit includes an analog signal conditioning circuit and an analog-to-digital converter. The analog signal conditioning circuit converts the data acquired by the high-precision sensor into a standard electrical signal and then sends it to the analog-to-digital converter for digital processing. The digitized data is transmitted to the main control unit 4 via the SPI bus.

[0090] All power converters are mounted on the main circuit board of the energy storage system and connected to the corresponding sodium-ion batteries via wires. The core of the power converter is a high-frequency switching device, which is connected to the main control unit 4 through a drive circuit to receive the phase angle control signal from the main control unit 4. The SOC acquisition module 2 is located inside the monitoring unit of the energy storage system and consists of a high-precision sensor and a data processing circuit. The high-precision sensor is used to collect the voltage, current and temperature data of the sodium-ion batteries in real time. After being processed by the analog signal conditioning circuit and the analog-to-digital converter, the data is transmitted to the main control unit 4 for subsequent calculation and analysis. In addition, the SOC acquisition module 2 also includes an independent clock circuit to record the sampling time point to ensure the accuracy of the time base when calculating the SOC value using the ampere-hour integration method.

[0091] Preferably, the equalization control module 3 includes a microcontroller, which communicates with the main control unit 4 via an I2C bus;

[0092] The main control unit 4 includes a high-performance processor for performing calculations of the SOC value of the sodium-ion battery, calculations of the phase shift angle adjustment of each power converter, and optimization of the genetic algorithm.

[0093] The equalization control module 3 is integrated on the equalization control board of the energy storage system and is directly connected to the carrier phase-shift modulation module 1 via a signal line. The core of the equalization control module 3 is a microcontroller, which communicates with the main control unit 4 via an I2C bus to receive data such as the SOC deviation matrix and global SOC deviation index. The equalization control module 3 generates specific equalization commands based on the received data and sends them to the power converter in the carrier phase-shift modulation module 1 to perform energy transfer operations. The equalization control module 3 also includes a protection circuit to monitor whether the voltage, current, and temperature of the sodium-ion battery exceed the safe range. Once an abnormality is detected, the equalization operation is immediately cut off and an alarm signal is sent to the main control unit 4.

[0094] The main control unit 4 is the core control component of the entire system, installed inside the main control box of the energy storage system. The main control unit 4 communicates with the carrier phase-shift modulation module 1, the SOC acquisition module 2, and the equalization control module 3 via the CAN bus 5. The communication protocol uses a time-triggered mechanism to improve real-time performance and reliability. The main control unit 4 contains a high-performance processor used to run core programs such as the SOC calculation algorithm, phase angle update algorithm, and genetic algorithm. The processor receives real-time data from the SOC acquisition module 2 via the CAN bus 5 and calculates the SOC value of each sodium-ion battery based on the ampere-hour integration method. Subsequently, the main control unit 4 constructs an SOC deviation matrix based on the calculation results and calculates the global SOC deviation index. ,when When the preset threshold is exceeded, the main control unit 4 generates a corresponding phase angle update and adjustment command and sends it to the carrier phase shift modulation module 1 via the CAN bus 5, and at the same time sends an equalization start command to the equalization control module 3.

[0095] In practical applications, this invention can be applied to large-scale sodium-ion energy storage power stations. For example, in a certain energy storage power station, there are 100 sodium-ion batteries connected in series to form a sodium-ion battery pack, with each sodium-ion battery having a nominal capacity of 100Ah. After the system starts up, the SOC acquisition module 2 collects the voltage, current, and temperature data of each sodium-ion battery in real time through high-precision sensors, and calculates the initial SOC value based on the ampere-hour integration method. Assuming the initial SOC values ​​are 90%, 85%, 80%...5%, the main control unit 4 constructs an SOC deviation matrix based on these data and calculates the global SOC deviation index. .when When the preset threshold is exceeded, the main control unit 4 generates a phase shift angle update command and sends it to the carrier phase shift modulation module 1 via the CAN bus 5. The carrier phase shift modulation module 1 adjusts the phase shift angle of each power converter according to the received phase shift angle update command, prioritizing the participation of sodium-ion batteries with larger SOC deviations in the equalization process. The equalization control module 3 generates specific equalization commands based on the equalization start command from the main control unit 4 and sends them to the power converters in the carrier phase shift modulation module 1 to execute energy transfer operations. After multiple iterations, the SOC values ​​of all sodium-ion batteries gradually converge, eventually reaching an equalized state.

[0096] To enable those skilled in the art to fully understand and implement this invention, the specific implementation principle of this invention is further explained below in conjunction with a specific application scenario.

[0097] In a large-scale sodium-ion energy storage power station, 100 sodium-ion batteries are connected in series to form a sodium-ion battery pack, each with a nominal capacity of 100Ah. After the system starts up, high-precision sensors in the SOC acquisition module 2 begin to collect voltage, current, and temperature data of each sodium-ion battery in real time. These sensors are installed near the positive and negative terminals of each sodium-ion battery, and the collected data is converted into standard electrical signals by an analog signal conditioning circuit and sent to an analog-to-digital converter for digital processing. The digitized data is transmitted to the main control unit 4 via the SPI bus for subsequent calculation and analysis.

[0098] After receiving the data, the main control unit 4 calculates the initial SOC value of each sodium-ion battery based on the ampere-hour integration method. Assuming the initial SOC values ​​are 90%, 85%, 80%, ... 5%, the main control unit 4 constructs the SOC deviation matrix D based on these data. At the same time, the main control unit 4 defines a global SOC deviation index. The root mean square value of the SOC difference for all sodium-ion batteries is the global SOC deviation index. When the preset threshold is exceeded ("preset threshold ϵ≤5% (corresponding to 100Ah battery pack capacity)", the main control unit 4 generates a phase shift angle update command and sends it to the carrier phase shift modulation module 1 through the CAN bus 5.

[0099] The phase shift angle is adjusted by the PWM signal issued by the main control unit 4. The PWM signal is isolated and amplified before being input to the drive circuit of the power converter, thereby changing the output characteristics of the power converter to achieve precise energy distribution.

[0100] The phase angle update formula is as follows

[0101] in Let be the phase shift angle of the i-th power converter in the k-th iteration. and These are the proportional and integral coefficients, respectively. .

[0102] The equalization control module 3 generates specific equalization commands based on the equalization start command from the main control unit 4, and sends them to the power converter in the carrier phase shift modulation module 1 to perform energy transfer operations.

[0103] After completing one equalization operation, the SOC acquisition module 2 reacquires the voltage, current, and temperature data of each sodium-ion battery and recalculates the SOC value based on the ampere-hour integration method. The main control unit 4 updates the SOC deviation matrix according to the new SOC value and recalculates the global SOC deviation index. .when If the value is less than the preset threshold ϵ, the main control unit 4 stops the equalization operation; otherwise, it returns to the phase angle update step and continues execution. Furthermore, the main control unit 4 also uses a genetic algorithm to adjust the scaling factor. Integral coefficient and maximum energy transfer For optimization, the genetic algorithm employs a tournament selection strategy with a crossover probability of 0.8, a mutation probability of 0.05, a population size of 50, and 100 iterations. The objective function is to minimize the global SOC deviation index. The formula is

[0104] The constraints include the voltage range, current limit, and temperature rise limit of the sodium-ion battery.

[0105] In actual operation, the system achieves dynamic equalization and calibration of the sodium-ion battery's State of Charge (SOC) through the above steps. For example, in the initial stage, sodium-ion batteries with larger SOC deviations participate in the equalization process first. The carrier phase-shift modulation module 1 adjusts the phase shift angle of each power converter according to the received phase shift angle update command, transferring energy from sodium-ion batteries with higher SOCs to those with lower SOCs. After multiple iterations, the SOC values ​​of all sodium-ion batteries gradually converge, eventually reaching an equalized state. During this process, the system significantly improves the performance consistency of the sodium-ion battery pack and extends its service life through high-precision sensors and real-time data processing, while also reducing safety risks caused by SOC imbalances.

[0106] The experimental platform used to verify the equalization capability and control accuracy of the sodium-ion energy storage SOC dynamic equalization and calibration method combining carrier phase shift modulation proposed in this invention under unbalanced SOC scenarios is shown in the table below:

[0107]

[0108] The experimental steps are as follows:

[0109] Step 1: Initialization

[0110] The initial SOC is set as shown in column 2 of the table below; the equalization threshold ϵ is set to 2%;

[0111]

[0112] Step 2: Real-time data acquisition and SOC calculation: SOC acquisition module 2 acquires voltage, current and temperature at a frequency of 1Hz; main control unit 4 uses the ampere-hour integration method to calculate SOC in real time and construct the SOC deviation matrix.

[0113] Step 3: Phase Shift Angle Update and Energy Transfer: Main Control Unit 4 updates the phase angle and transfers energy according to the formula.

[0114]

[0115] Update the phase shift angle of each power converter; transfer energy from high SOC battery to low SOC battery, with each transfer amount ≤5Ah.

[0116] Step 4: Iteration and convergence judgment: After each round, recalculate the global SOC deviation index δ; stop balancing when δ < 2% and record the final SOC value.

[0117] The experimental results are shown in the table below:

[0118]

[0119] The experimental results are interpreted as follows:

[0120] Initial SOC: The SOC value of each battery is set manually before the experiment begins, simulating a "severely unbalanced" working condition (maximum 90%, minimum 60%).

[0121] SOC after equilibration 1 / 3 / 5: The trend of SOC change after each round of equilibration shows that the SOC of high SOC batteries (such as B1) gradually decreases, while the SOC of low SOC batteries (such as B10) rises rapidly, showing a "convergence" trend.

[0122] Final SOC: At the end of the experiment, the SOC of all batteries was concentrated between 79.0% and 79.8%, with a maximum difference of only 0.8%, which met the threshold of δ<2%.

[0123] Convergence rounds: Most cells reached stability in the 4th to 5th rounds, indicating that the system converged quickly (total time was about 7 minutes).

[0124] Key Phenomenon Analysis:

[0125] Convergence speed: High SOC batteries (B1~B3) decreased by 2.5%~3% in the first round, while low SOC batteries (B8~B10) increased by 5%~8% in the first round, showing significant energy transfer efficiency.

[0126] Equalization accuracy: The final global SOC deviation δ=1.8%, which is better than traditional passive equalization (usually δ>5%).

[0127] Temperature rise control: During the experiment, the battery pack's maximum temperature rise was 3.7°C (ambient temperature 25°C), and the protection circuit was not triggered.

[0128] Experimental results show that the proposed sodium-ion energy storage SOC dynamic equalization and calibration method combining carrier phase-shift modulation can reduce the SOC deviation of 10 sodium-ion batteries from 10.1% to 1.8% within 5 iterations, meeting the system's set equalization threshold requirements. The energy transfer process is stable, and temperature rise and voltage fluctuations are within safe ranges, verifying the system's high efficiency, stability, and intelligence, making it suitable for large-scale sodium-ion energy storage systems.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sodium-ion energy storage SOC dynamic balancing and calibration method combined with carrier phase shift modulation, characterized in that, The application relates to a sodium ion energy storage system and a balancing and calibration method thereof. Step S1: connecting each power converter with a sodium ion battery; Step S2: collecting voltage, current and temperature data of each sodium ion battery in real time through an SOC acquisition module, and calculating the SOC value of the sodium ion battery based on the ampere-hour integral method; Step S3: constructing a global SOC deviation index based on the SOC value of the sodium ion battery; Step S4: updating the phase shift angle of each power converter based on the global SOC deviation index; Step S5: transferring the energy of the sodium ion battery with a higher SOC to the sodium ion battery with a lower SOC through the carrier phase shift modulation module; Step S6: after completing a balancing operation, the SOC value of each sodium ion battery is recalculated, the global SOC deviation index is updated, and when the global SOC deviation index is less than a preset threshold, the balancing operation is stopped, otherwise, the step S4 is returned; Step S7: based on historical operation data, a genetic algorithm is used to optimize the global SOC deviation index based on the minimum global SOC deviation index as the target; Step S8: the carrier phase shift modulation module, the SOC acquisition module, the balancing control module and the master control unit are integrated into the sodium ion energy storage system, and the master control unit is connected with the carrier phase shift modulation module, the SOC acquisition module and the balancing control module in communication through the CAN bus; The formula for adjusting the phase shift angle of each power converter in step S4 is: ； wherein is the i th power converter in the th iteration, and are the proportional and integral coefficients, respectively.

2. The sodium-ion energy storage SOC dynamic balancing and calibration method with carrier phase-shift modulation according to claim 1, characterized in that, The initial phase shift angle of the plurality of power converters in step S1 is: ； wherein, N is the number of sodium-ion batteries, and the adjustment of the phase shift angle is achieved by the PWM signal issued by the master control unit.

3. The sodium-ion energy storage SOC dynamic balancing and calibration method with phase-shifted modulation of the combined carrier according to claim 1, characterized in that, The calculation formula for calculating the SOC value of the sodium ion battery in step S2 is: ； wherein, is the SOC value of the i-th sodium-ion battery at time t, is the initial SOC value, is the nominal capacity of the sodium-ion battery, is the current of the i-th sodium-ion battery.

4. The sodium-ion energy storage SOC dynamic balancing and calibration method with phase-shifted modulation of the combined carrier according to claim 1, characterized in that, The specific steps of step S3 are: According to the SOC value of the sodium ion battery, an SOC deviation matrix is constructed, elements of which represent the SOC difference between the first sodium ion battery and the nth sodium ion battery, and the formula is as follows: i j ​​​ ； Define the global SOC deviation index For all sodium-ion battery SOC difference values, the root mean square value is: ； Where N represents the number of sodium-ion batteries. , The first i The, the j The SOC value of a sodium-ion battery.

5. The sodium-ion energy storage SOC dynamic balancing and calibration method with carrier phase-shift modulation of claim 1, wherein, The energy transfer amount formula of step S5 is: ； wherein is the amount of energy transferred, and are sodium-ion batteries with the highest and lowest SOC, respectively, is the maximum amount of energy transferred allowed for a single equalization operation.

6. The sodium-ion energy storage SOC dynamic balancing and calibration method with phase-shifted carrier modulation according to claim 5, characterized in that, The specific steps of step S7 are: Based on historical operation data, the proportional coefficient , integral coefficient and maximum energy transfer amount are optimized by using genetic algorithm, and the objective function is the minimum global SOC deviation index , whose formula is: ； The constraint conditions of the objective function include the voltage range, current limit and temperature rise limit of the sodium ion battery.

7. The sodium-ion energy storage SOC dynamic balancing and calibration method with carrier phase-shift modulation of claim 1, wherein, The control signal output end of the carrier phase shift modulation module is connected with the circuit board of the sodium ion battery, the control signal input end of the carrier phase shift modulation module is connected with the control signal output end of the master control unit through the CAN bus, the SOC acquisition module is connected with the monitoring end of the sodium ion energy storage system, the signal output end of the SOC acquisition module is connected with the signal input end of the master control unit, the balancing control module is integrated on the balancing control board of the sodium ion energy storage system and is directly connected with the carrier phase shift modulation module through a signal line, and the control signal input end of the balancing control module is connected with the control signal output end of the master control unit.

8. The sodium-ion energy storage SOC dynamic balancing and calibration method with carrier phase-shift modulation of claim 1, wherein, The power converter comprises high-frequency switching devices connected with the master control unit through a driving circuit, the SOC acquisition module comprises high-precision sensors and a data processing circuit, the high-precision sensors are installed near the positive and negative electrodes of each sodium ion battery, and the high-precision sensors comprise voltage sensors, current sensors and temperature sensors, the data processing circuit comprises an analog signal conditioning circuit and an analog-to-digital converter, the analog signal conditioning circuit converts the data collected by the high-precision sensors into standard electrical signals and then sends the standard electrical signals to the analog-to-digital converter for digital processing, and the digital data is transmitted to the master control unit through an SPI bus.

9. The sodium-ion energy storage SOC dynamic balancing and calibration method with carrier phase-shift modulation of claim 1, wherein, The equalization control module comprises a microcontroller, and the microcontroller communicates with the master control unit through an I2C bus. The master control unit comprises a high-performance processor, which is used for running the SOC value calculation of the sodium ion battery, the adjustment calculation of the phase shift angle of each power converter and the optimization of the genetic algorithm.

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