Battery management system, battery management method, battery pack, and electric vehicle
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Solution Overview
Problem
Existing battery management systems fail to effectively suppress over-potential during charging, leading to accelerated battery degradation, lithium metal deposition, and potential internal short circuits.
Innovation Solution
A battery management system that updates over-potential management information based on previous charging cycles and differential capacity curves, adjusting charge conditions to prevent excessive over-potential by modifying C-rates and charging thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high charging current (high C-rate) is applied to charge the battery quickly, then charging speed and productivity are improved, but over-potential increases causing accelerated battery degradation and lithium metal deposition
Solution Approach 1:
The charging current is dynamically adjusted based on real-time monitoring of differential capacity curves. The system transitions from fixed C-rate charging to adaptive charging where the current is modulated according to the battery's instantaneous state, particularly when peaks in the differential capacity curve are detected, preventing over-potential while maintaining high average charging speed
Solution Approach 2:
The system continuously monitors charging parameters and updates over-potential management information based on differential capacity curve analysis. This feedback mechanism allows the system to detect early signs of over-potential (through peak detection in dQ/dV curves) and adjust charging current accordingly, creating a closed-loop control system that balances speed and safety
2Productivity
If constant high C-rate charging is used, then charging efficiency is improved, but polarization becomes severer leading to larger over-potential and battery degradation
Solution Approach 1:
The system employs periodic analysis of differential capacity curves during charging to detect peaks that indicate approaching over-potential conditions. This periodic monitoring allows the system to maintain high charging rates during safe periods while intermittently reducing current when peaks are detected, achieving a balance between efficiency and harm reduction
Solution Approach 2:
The charging current parameter is changed based on the state of the differential capacity curve. When the curve shows peaks indicating severe polarization, the system reduces the C-rate parameter; when the curve is smooth indicating mild polarization, the system maintains high C-rate. This dynamic parameter adjustment resolves the contradiction between charging efficiency and over-potential prevention
3Device complexity
If charging continues without monitoring over-potential, then device complexity is reduced, but battery degradation accelerates due to uncontrolled over-potential
Solution Approach 1:
The system replaces complex physical monitoring equipment with computational analysis of electrical parameters. By calculating differential capacity curves from standard voltage and current measurements, the system achieves over-potential detection without additional sensors or complex hardware, maintaining device simplicity while improving reliability
Solution Approach 2:
The battery management system uses the battery's own electrical characteristics (voltage and current during charging) to self-diagnose over-potential conditions through differential capacity curve analysis. This self-service approach eliminates the need for external monitoring systems while extending battery lifespan through intelligent control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively suppresses over-potential, preventing lithium deposition and internal short circuits, thereby extending battery lifespan and ensuring safe charging operations.
Implementation Method 1
While a battery is being charged, polarization occurs in the battery. The polarization depends on a plurality of resistance components (for example, Ohm resistance, electric charge transfer, diffusion resistance) of the battery.
Implementation Method 2
when the voltage of the negative electrode of the battery drops below 0 V due to the over-potential, lithium metal deposition rapidly occurs on the negative electrode surface
Data Source
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AI summary
A battery management system according to the present disclosure includes a sensing unit to generate a sensing signal indicating a voltage and a current of a battery, a memory unit to store over-potential management information including a reference peak value and a reference peak voltage value, and a control unit to command first constant-current charging using a maximum allowable C-rate to a charging circuit when the reference peak value is equal to or larger than a threshold peak value, in response to a charge request. The control unit determines a first differential capacity curve indicating a correlation between the voltage and differential capacity of the battery in a threshold voltage range based on the sensing signal collected during the first constant-current charging. The control unit determines a first main peak value and a first main peak voltage value indicating a differential capacity and a voltage of a first peak of the first differential capacity curve, respectively. The control unit updates the reference peak value and the reference peak voltage value to be equal to the first main peak value and the first main peak voltage value, when the first main peak value is less than the threshold peak value.