A battery management method based on single primitive state balancing

Abstract

The application discloses a battery management method based on single-primitive state balance, and belongs to the technical field of battery management. The method comprises the following steps: a state acquisition step, namely, collecting the voltage, current and temperature parameters of each cell unit in real time; a state evaluation step, namely, calculating the state of charge and the health state of each cell unit according to the collected parameters; a balance calculation step, namely, inputting the state parameters of each cell unit into a balance control module, and calculating the balance current value corresponding to each cell unit through a single composite operation composed of exponential operation, logarithmic operation and difference operation; a balance execution step, namely, controlling the switch state of the balance circuit of each cell unit according to the calculation result, so that the state of charge difference between each cell unit converges to within a preset threshold; and a closed-loop feedback step, namely, repeatedly executing the above steps until each cell unit reaches a preset balance state. The application realizes efficient balance of the battery pack through single composite operation balance control, and the balance precision and speed are superior to those of a traditional passive balance scheme.

Description

Technical Field

[0001] This invention belongs to the field of battery management technology, specifically relating to a management method and system for achieving efficient and balanced battery pack management through a single composite operation closed-loop control, applicable to battery management of energy storage systems such as lithium battery packs, solid-state battery packs, and sodium-ion battery packs. Background Technology

[0002] The battery management system (BMS) is the core of a battery pack's safe operation and lifespan management. A battery pack consists of multiple cells connected in series or parallel. Individual differences in manufacturing processes and operating environments lead to inconsistencies in the state of charge (SOC) of each cell during charging and discharging. Without balancing control, these differences will increase with the number of cycles, causing some cells to be overcharged or over-discharged, severely impacting the battery pack's usable capacity and lifespan.

[0003] Existing equalization technologies are mainly divided into passive equalization and active equalization. Passive equalization dissipates the energy of high-voltage cells through parallel resistors. It has a simple structure, but the energy is dissipated as heat, resulting in low equalization efficiency. The equalization current is usually no more than 100mA. Active equalization transfers energy between cells through energy storage components such as inductors, capacitors, or transformers. It has higher efficiency, but the control algorithm is complex, requiring multi-level threshold judgments and state machine logic, and the parameter tuning workload is large.

[0004] In recent years, the concept of a single control primitive has been validated in the field of computing, with researchers proposing the use of a single mathematical function to achieve general-purpose computation, significantly simplifying system architecture. However, a technical solution for applying single-primitive equalization control to battery management has not yet been publicly disclosed. Therefore, a novel method that deeply integrates single-primitive equalization control with battery management is urgently needed.

[0005] The technical concept of this invention is inspired by the ancient Chinese philosophy of symbolism and numerology, and combined with modern battery management technology. Summary of the Invention

[0006] This invention provides a battery management method based on single primitive state equalization, including a state acquisition step, a state evaluation step, an equalization calculation step, an equalization execution step, and a closed-loop feedback step. A battery management system for implementing this method is also provided. Detailed Implementation

[0007] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can refer to and implement it.

[0008] Example 1: Basic Equilibrium Control Process The battery pack consists of six lithium-ion battery cells connected in series, each with a rated voltage of 3.7V and a rated capacity of 2600mAh. The parameter acquisition module collects the parameters of each cell in real time through a voltage sampling chip, a current sampling resistor, and a thermistor. The voltage sampling chip uses a multi-channel 16-bit analog-to-digital converter (ADC) with a voltage acquisition accuracy of ±5mV and a sampling frequency of 1kHz per channel. The current sampling resistor is a 0.005Ω precision resistor with an accuracy of 0.1%, and the voltage across it is amplified 100 times by an instrumentation amplifier before being sent to the ADC. The temperature sensor uses a negative temperature coefficient thermistor with an accuracy of ±1℃, attached to the surface of each cell.

[0009] The state assessment module calculates the state of charge (SOC) value of each cell using a combination of the ampere-hour integral method and the open-circuit voltage method. The ampere-hour integral method is updated under dynamic operating conditions, while the open-circuit voltage method is calibrated under static operating conditions. The health state value is calculated through internal resistance estimation and capacity decay tracking, with a reference temperature of 25℃.

[0010] Assume that at a certain moment, the state of charge (SBC) of cell one is 85%, the average SBC of the six cells in the group is 80%, and the SBC difference of cell one is +5%. The baseline value is preset to 1.0. The equalization calculation module calculates the equalization current value through a single composite operation: Equalization current value = e^(+5%) - ln(1.0) ≈ 1.051 - 0 = 1.051. A positive output value indicates that the SBC of cell one is higher than the average value in the group, and discharge equalization needs to be performed on this cell.

[0011] The equalization execution module controls the discharge switch in the bidirectional equalization circuit corresponding to cell one to be turned on. The bidirectional equalization circuit adopts an inductor-based active equalization topology, with a peak equalization current of 2A and an operating frequency of 100kHz. The discharge equalization path is: positive terminal of cell one → discharge switch → energy storage inductor → DC bus within the group → positive terminal of other cells. During the discharge equalization process, excess charge in cell one is transferred to the DC bus within the group via the energy storage inductor, and then distributed by the DC bus to other cells with lower state of charge.

[0012] After a period of discharge equalization, the state of charge (SOC) of cell one decreased from 85% to 81%, while the group average rose to 80.5%, narrowing the difference to +0.5%. Substituting back into the function: Equalization current = e^(+0.5%) - ln(1.0) ≈ 1.005 - 0 = 1.005. As the output value decreases, the equalization current also decreases. When the difference approaches zero, the equalization current also approaches zero, and the equalization process stops. Ultimately, the SOC difference between the cells is controlled within ±1%, and equalization is complete.

[0013] Example 2: Parallel processing for multi-cell unevenness When the state of charge (SOC) of cell one is above average and the SOC of cell two is below average, the balancing calculation module calculates the single composite operation output value for both. A positive output value for cell one triggers discharge balancing; a negative output value for cell two triggers charging balancing. The two sets of bidirectional balancing circuits operate simultaneously without interference. Energy discharged from cell one is absorbed by cell two via the DC bus, achieving direct energy transfer between cells with an energy transfer efficiency of approximately 85%. The entire balancing process is completed within the same control cycle, which is 100 milliseconds.

[0014] Example 3: Temperature Compensation and Safety Protection During the balancing process, the balancing current value is also modulated by temperature parameters. When the temperature of a cell exceeds 45℃, the balancing current value of that cell is automatically halved; when the temperature exceeds 55℃, the balancing operation of that cell is suspended until the temperature drops below 45℃ and resumes. The voltage and temperature parameters of each group of cells are monitored in real time by the closed-loop control module. If the voltage of any cell exceeds 4.2V or falls below 2.8V, a protection alarm is triggered, all balancing circuits are forcibly shut down, and the battery pack enters a safety protection state. The temperature compensation and safety protection logic is implemented in hardware logic in the balancing calculation module, with a response latency of less than 1 millisecond. Beneficial effects

[0015] By replacing traditional multi-level threshold judgment with a single composite operation closed-loop control, the equalization control architecture is simplified, requiring only two control parameters: a reference value and a temperature threshold, significantly reducing parameter tuning workload. The single composite operation output changes continuously, and the equalization current dynamically adjusts with the state-of-charge difference. When the difference is +5%, the equalization current is approximately 2.1A; when the difference decreases to +0.5%, the equalization current drops to approximately 1.0A. The equalization accuracy and speed are superior to traditional fixed-threshold schemes. The bidirectional active equalization circuit supports bidirectional energy transfer during charging and discharging, with an energy transfer efficiency of approximately 85%, significantly higher than passive equalization schemes. Temperature compensation and safety protection are implemented using hardware logic, with a response latency of less than 1 millisecond, ensuring system safety and reliability. Attached Figure Description

[0016] Figure 1 Overall Flowchart of Battery Management Method Figure 2 Battery Management System Overall Block Diagram Figure 3 Schematic diagram of single composite operation equalization control principle.

Claims

1. A battery management method based on single primitive state equalization, characterized in that, Includes the following steps: S1: Status Acquisition Steps - Real-time acquisition of voltage, current, and temperature parameters of each cell unit in the battery pack; S2: Status assessment step - Calculate the state of charge and health status of each cell based on the voltage, current and temperature parameters. S3: Equalization Calculation Step - Input the state parameters of each cell unit into the equalization control module, and calculate the equalization current value corresponding to each cell unit through a single composite operation consisting of exponential operation, logarithmic operation and difference operation. The single composite operation uses the difference in state of charge between each cell unit as the input variable. S4: Equalization execution step - Control the switching state of the equalization circuit corresponding to each cell unit according to the equalization current value, so that the difference in the state of charge between each cell unit converges to within the preset threshold. S5: Closed-loop feedback step - Repeat S1 to S4 until each cell unit reaches the preset balance state.

2. The battery management method according to claim 1, characterized in that, The single composite operation in step S3 uses the following function: Equalization current value = e^(state of charge difference) - ln(reference value), where the state of charge difference is the difference between the current state of charge value of the cell and the average state of charge value in the group, and the reference value is a preset state of charge reference value.

3. The battery management method according to claim 1, characterized in that, The balancing circuit mentioned in step S4 is a bidirectional balancing circuit; when the state of charge of a certain cell is higher than the average value in the group, discharge balancing is performed on the cell, and the excess power is transferred to other cell cells in the group through the bidirectional balancing circuit; when the state of charge of a certain cell is lower than the average value in the group, charge balancing is performed on the cell, and power is obtained from other cell cells in the group through the bidirectional balancing circuit.

4. The battery management method according to claim 2, characterized in that, When the output value of the single composite operation in step S3 approaches zero, each cell unit reaches a balanced state; when the output value deviates from zero, the balanced current value is automatically adjusted to bring the output back to zero.

5. The battery management method according to claim 1, characterized in that, The battery pack mentioned in step S1 is a lithium battery pack, a solid-state battery pack, or a sodium-ion battery pack, and the number of battery cells is an integer of not less than 2.

6. A battery management system based on single primitive state equalization, used to execute the battery management method according to any one of claims 1 to 5, characterized in that, include: The parameter acquisition module is used to collect the voltage, current and temperature parameters of each cell in the battery pack in real time. The status assessment module, connected to the parameter acquisition module, is used to calculate the state of charge and health status of each cell unit based on the acquired parameters. The equalization calculation module, connected to the state evaluation module, has a built-in single composite calculation unit consisting of an exponential calculation circuit, a logarithmic calculation circuit, and a difference calculation circuit, which is used to calculate the corresponding equalization current value based on the state parameters of each cell unit. The equalization execution module, connected to the equalization calculation module, includes equalization circuits corresponding to each cell unit, and is used to control the switching state of the equalization circuits according to the equalization current value. A closed-loop control module is connected to the equalization execution module and the parameter acquisition module respectively, and is used to determine the equalization state and control the above modules to execute cyclically.

7. The battery management system according to claim 6, characterized in that, The equalization calculation module has a preset single composite operation function: equalization current value = e^(state of charge difference) - ln(reference value), where the state of charge difference is the difference between the current cell's state of charge value and the group's average state of charge value, and the reference value is a preset state of charge reference value. When the output value deviates from zero, the equalization current value is automatically adjusted to bring the output back to zero.

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