Battery Cell State of Health Estimation via Voltage Crossing Detection
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Solution Overview
Problem
Existing methods for determining the state of health (SOH) of battery cells require full discharge and recharge cycles, which are resource-intensive and constraining in certain applications.
Innovation Solution
A method involving measuring voltage across the cell at multiple times during charge or discharge, detecting a specific voltage crossing point characteristic of different health states, and using this information to estimate SOH without the need for full discharge or charge cycles, utilizing a battery management device capable of dynamically reconfiguring cell connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full discharge and recharge cycles are used to determine cell capacity, then measurement precision of cell capacity is improved, but loss of time and productivity deteriorate
Solution Approach 1:
The patent applies partial action by measuring voltage at multiple specific times during charge/discharge cycles without completing full cycles. Instead of fully charging and discharging the cell to determine capacity, the method measures voltage at several intermediate time points and uses these partial measurements to estimate SOH, significantly reducing the time required while maintaining acceptable measurement precision.
Solution Approach 2:
The patent uses preliminary action by performing voltage measurements at multiple predetermined time points during charge/discharge processes. These preliminary voltage measurements are used to detect crossings of specific voltage values and estimate SOH before full charge/discharge cycles are completed, allowing for time-efficient health assessment without waiting for complete cycles.
2Measurement precision
If full discharge and recharge cycles are performed, then cell capacity measurement accuracy is improved, but device complexity and operational constraints increase
Solution Approach 1:
The method uses partial charge/discharge measurements instead of complete cycles. By measuring voltage at multiple intermediate time points and using the crossing detection method, the system achieves sufficient accuracy for SOH estimation without requiring full charge/discharge operations, thereby improving ease of operation and reducing constraints on battery usage.
Solution Approach 2:
The patent introduces voltage crossing detection as an intermediary method between direct capacity measurement and simple voltage reading. By detecting when voltage crosses specific predetermined values during charge/discharge and combining this with time-based charge quantity estimation, the system obtains SOH information without requiring complete charge/discharge cycles or complex direct capacity measurement apparatus.
3Measurement precision
If voltage is measured at multiple times during charge/discharge, then SOH estimation accuracy is improved, but measurement complexity increases
Solution Approach 1:
The method performs multiple voltage measurements at predetermined time points during charge/discharge cycles. This partial sampling approach provides sufficient data for accurate SOH estimation through crossing detection, avoiding the need for continuous monitoring or excessive measurements that would increase device complexity.
Solution Approach 2:
The patent changes the measurement parameter from direct capacity measurement to voltage measurement at specific time points. By monitoring voltage crossings of predetermined values and combining with time-based charge quantity estimation, the system achieves accurate SOH estimation using simple voltage sensors and timing, reducing the complexity of measurement devices and processing requirements.
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
Enables reliable SOH determination without the need for full discharge or charge cycles, allowing for more frequent readjustments and simpler estimation algorithms, reducing the operational constraints of existing systems.
Implementation Method 1
An electric battery is a group of a plurality of rechargeable elementary cells (cells, accumulators, etc.) connected in series and/or in parallel between two voltage supply nodes or terminals
Data Source
AI summary
A method of determining the state of health of a first elementary cell of a battery, including the steps of: measuring the voltage across the cell under a reference current at a plurality of times in a phase of cell charge or discharge between first and second state-of-charge levels; and detecting a crossing by the voltage of a predetermined specific value, corresponding to a predetermined specific charge value of the cell.