A battery charge and discharge management method based on proportional stress balance

Abstract

This invention discloses a battery charge and discharge management method based on proportional stress balance, belonging to the field of battery management system technology. It addresses the problems of rigid fixed threshold control, cell stress concentration, easy bulging and degradation, and insufficient safety in existing battery management systems. This method establishes a multi-parameter linked proportional stress model by real-time acquisition of battery voltage, current, temperature, and cell health parameters. A programmable dynamic algorithm adjusts the charge and discharge power, abandoning traditional threshold jump control, achieving continuous proportional smooth control of charge and discharge current and voltage, accurately matching the cell's safe stress range, and reducing polarization loss and thermal runaway risk. This invention requires no modification to battery hardware; it achieves improved battery range, extended cycle life, and no bulging or swelling only through algorithm iteration. It is applicable to vehicle power batteries, drones, robots, and portable energy storage batteries, with strong compatibility, low implementation cost, and can be directly embedded into existing BMS battery management systems.

Description

Technical Field

[0001] This invention relates to battery management system (BMS) control technology, specifically to a method based on dynamic proportional stress balance. The balanced intelligent battery charging and discharging management method can be directly programmed and embedded into BMS microcontrollers and MCU chips for execution. It is applied to the charging and discharging control of various lithium-ion batteries and energy storage batteries. Background Technology

[0002] Existing battery management systems (BMS) generally use fixed voltage and fixed current thresholds for charge / discharge cutoff control. The design does not take into account the dynamic correlation between battery temperature, cell aging, and load fluctuations, and has many technical defects: 1. Fixed threshold control uses a discrete switching mode, directly cutting off power supply when the charge / discharge reaches the threshold, causing instantaneous changes within the battery cell. Stress impacts over time and long-term use can cause cell bulging, expansion, and accelerated degradation. 2. The dynamic proportional relationship between various battery parameters has not been established, making it unable to adapt to different aging levels and temperature environments. The battery cells are in a state of low charge and discharge efficiency and high energy loss. 3. The control strategy lacks continuous adjustability, and is prone to thermal runaway, overcharging, and over-discharging under high temperature, low temperature, and high load conditions. The problem is insufficient security. 4. Existing algorithms lack dynamic stress correction logic, resulting in short battery cycle life and high maintenance and replacement costs.

[0003] This invention addresses the aforementioned technical pain points by proposing a programmable control scheme based on proportional stress balance, thus filling the gap in dynamic... There is a technological gap in continuous proportional control. Summary of the Invention

[0004] 1. Achieve continuous and smooth proportional control of battery charging and discharging, eliminating instantaneous stress shocks and reducing cell bulging at its source. Issues such as spontaneous combustion and degradation; 2. Establish a multi-parameter proportional stress model for voltage, current, temperature, and cell health (SOH) to achieve full-process... Adaptive control based on conditions; 3. Provides complete algorithm logic that is directly programmable and executable on the chip, requiring no battery replacement or additional hardware. 4. Directly adapts to existing BMS systems; improves battery energy utilization, achieving increased range with the same battery capacity, extending battery cycle life, and reducing... Usage cost.

[0005] This invention relies on existing battery management system (BMS) hardware and requires no additional sensors or modifications to the battery. The core implementation method of the pool structure is: real-time parameter acquisition + proportional stress model calculation + programmable algorithm input. The solution uses a closed-loop control based on the +PWM signal, and can be programmed directly using C or Python. Recorded to the BMS main control MCU chip and executed by the microcontroller. 1. The real-time parameter acquisition module (implemented in existing BMS hardware, no modification required) utilizes the BMS's built-in sensors. The battery's core operating parameters are collected synchronously at 100ms intervals to provide a data source for proportional calculations. 2. 1. Individual cell voltage U, total battery pack voltage Utotal; 2. Real-time charging and discharging current I; 3. Cell surface temperature T; 4. Cell health status (SOH) (calculated by cell internal resistance and cycle count); 5. Remaining battery power (SOC). 3. Establishment of Proportional Stress Model (Core Algorithm, Directly Programmable): Establish the dynamic proportional stress calculation formula and determine... The cell safety stress threshold and proportional adjustment coefficient are fixed reference parameters in the program and dynamically corrected in real time. 4. 1. Divide the battery charge / discharge ratio range: Low capacity range: SOC ∈ 0%–20%, charge ratio coefficient K1 = 0.8–1.0. Allows for stable charging with high current; optimal health range: SOC ∈ 20%–80%, charging ratio coefficient K2 = 0.6–0.8. Maintain balanced stress charging; High charge range: SOC ∈ 80%–100%, charging ratio coefficient K3 = 0.1–0.3. Gradually reduce the charging current; 2. Temperature linkage proportional correction formula: When T∈0–45℃ (room temperature), the temperature proportionality coefficient Kt=1.0; when T<0℃ Or, when T>45℃, the temperature proportionality coefficient Kt=0.5–0.7, the automatic shrinkage stress range; 3. Cell aging correction formula: When SOH ≥ 80% (new cell), the aging ratio coefficient Ks = 1.0; when SOH < 80% (Aged battery cells), aging ratio coefficient Ks=0.6–0.9, reducing the upper limit of charge and discharge; 4. The total stress proportionality coefficient K = K_range × Kt × Ks, and the final control coefficient is between 0.1 and 1.0. 5. 6. 1. Charging control logic: Parameter acquisition → Calculation of total stress proportionality coefficient K → Reference charging current × K = Actual output Output charging current; after the battery level reaches 80%, the proportional coefficient decreases progressively for every 5% increase in battery level to avoid overcharging. Stress accumulation occurs; when the rated voltage upper limit is reached, the current drops below 5%, instead of being directly cut off, thus achieving... Smooth full charge. 2. Discharge control logic: Collect load demand → Calculate total stress proportionality coefficient K → Reference discharge current × K = Actual Actual output discharge current; under conditions of sudden load increase, ramping, and acceleration, the proportional coefficient increases smoothly, eliminating instantaneous [discharge current]. High current surge; when the charge is low, the proportional coefficient is gradually reduced to avoid over-discharge damage to the battery cell.

[0010] 3. Closed-loop feedback correction: The data acquisition-processing-output process is repeated every 100ms, and the scaling factor is corrected in real time. Ensure that the battery cells are always within the safe stress range. 7. After the signal output execution algorithm is processed, the BMS chip outputs a PWM pulse width modulation signal to directly control the signal output. The switching frequency of the MOSFET in the charging and discharging circuit is controlled to achieve continuous proportional regulation of current and voltage, with no interference throughout the entire process. Jump-type, no hard cut-off, complete proportional stress balance control. 8.

[0013] 1. Zero hardware modification: Fully compatible with existing BMS systems, it can be implemented simply by upgrading the algorithm, with extremely low implementation costs; 2. Gentler control: Continuous proportional smooth adjustment eliminates instantaneous stress on the battery cell, completely solving the problems of bulging and degradation; 3. Enhanced safety: Multi-parameter linkage correction automatically avoids risks under high and low temperatures and aging conditions, preventing thermal runaway; 4. More efficient use: Reduced polarization loss, resulting in 10%-15% longer battery life with the same battery capacity, and extended cycle life. More than 30% longer; 5. Highly practical: The algorithm has clear logic, is programmable, reproducible, and testable, making it easy to apply in batches. Detailed Implementation

[0014] Taking vehicle-mounted ternary lithium-ion batteries as an example, the complete implementation steps are as follows: 1. The BMS system collects cell voltage (4.0V), current (2A), temperature (30℃), and SOH (90%) every 100ms. SOC=60%; 2. Determined to be in the optimal health range, K range = 0.7, room temperature Kt = 1.0, new cell Ks = 1.0, total coefficient K = 0.7; 3. The reference charging current is 3A, and the actual output charging current is 3A × 0.7 = 2.1A; 4. When the battery level reaches 85%, the K range automatically drops to 0.4, and the charging current simultaneously drops to 1.2A; 5. When the temperature rises to 48℃, Kt automatically drops to 0.6, and the charging current is adjusted accordingly to avoid overheating; 6. When the vehicle accelerates during discharge, the load demand increases, the proportional coefficient is smoothly adjusted upward, and the output current is stable without impact; 7. No hard cutting or stress concentration throughout the process, stable cell temperature, no bulging after long-term use, significantly improved battery life and endurance. promote.

Claims

1. A battery charge / discharge management method based on proportional stress balance, characterized in that, Based on the existing BMS battery management system hardware, the following steps are implemented through programmable algorithms: (1) Collect battery cell voltage, total voltage, charge and discharge current, cell temperature, SOH (state of health), and SOC (state of charge) parameters in real time with a period of 100ms; (2) Establish a multi-parameter proportional stress model, divide the three proportional ranges into low charge, optimal health, and high charge, set the corresponding proportional coefficients for each range, and calculate the total stress proportional coefficient in combination with temperature and cell aging status; (3) Dynamically adjust the charge and discharge current according to the total stress proportional coefficient to achieve continuous and smooth control, and abandon the fixed threshold jump cut-off; (4) Correct the proportional coefficient in real time through closed-loop feedback so that the cell is always in the safe stress range, reducing the risk of bulging, decay and thermal runaway.

2. The method of claim 1, wherein, The proportional ranges are set as follows: SOC 0%-20% is the low power range, with a proportional coefficient of 0.8-1.0; SOC 20%-80% is the optimal health range, with a proportional coefficient of 0.6-0.8; SOC 80%-100% is the high power range, with a proportional coefficient of 0.1-0.

3.

3. The method of claim 1, wherein, The temperature proportional correction logic is as follows: the proportional coefficient is 1.0 at room temperature (0-45°C), and the proportional coefficient is adjusted to 0.5-0.7 when the temperature is <0°C or >45°C.

4. The method of claim 1, wherein, The cell aging correction logic is as follows: when SOH≥80%, the proportional coefficient is 1.0, and when SOH<80%, the proportional coefficient is reduced to 0.6-0.

9.

5. The method of claim 1, wherein, The algorithm can be programmed into the BMS main control MCU chip or microcontroller using C language, and outputs PWM signals to control the charging and discharging MOSFETs, which can be executed without modifying the battery hardware.

6. The method according to any one of claims 1 to 5, characterized in that, Suitable for vehicle power batteries, drone batteries, robot batteries, and various portable lithium-ion energy storage batteries.