Battery Cell State of Charge Recalibration via Voltage Crossing
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Solution Overview
Problem
Existing battery state of charge estimation methods degrade over time due to aging and require complete charging or discharging cycles for recalibration, which is restrictive and impractical in certain applications.
Innovation Solution
A method that measures voltage at the terminals of a battery cell during charging or discharging phases to detect a specific predetermined charge value, allowing for recalibration of the state of charge estimation algorithm without the need for full charge or discharge cycles, by identifying a crossing point of voltage curves representative of different aging states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complete charging or discharging cycles are implemented for recalibration, then the state of charge estimation accuracy is improved, but the operational constraints and time required are increased
Solution Approach 1:
The patent applies partial action by using only a portion of the charge/discharge cycle (a fraction of the full cycle) to achieve recalibration. Instead of requiring complete charging or discharging, the method detects a specific predetermined charge value (such as 0% or 100% SOC) during an ongoing cycle and uses this partial information to reset the estimation algorithm, significantly reducing the time and operational disruption required for recalibration while maintaining estimation accuracy.
2Measurement precision
If complete charging or discharging cycles are implemented for recalibration, then the state of charge estimation accuracy is improved, but the operational flexibility is reduced
Solution Approach 1:
The method enables recalibration during normal battery operation by detecting a predetermined charge value (such as full charge or empty charge) without requiring the system to undergo complete charging or discharging cycles. This partial approach allows the battery management system to maintain accurate SOC estimation while preserving operational flexibility and avoiding disruptions to the application's power requirements.
3Reliability
If frequent recalibration is performed, then the state of charge estimation accuracy is maintained, but the operational constraints increase
Solution Approach 1:
The patent enables frequent recalibration by using partial charge/discharge information. When the battery reaches a predetermined charge value (such as 0% or 100% SOC) during normal operation, the system can perform a quick reset of the estimation algorithm without requiring complete cycles. This allows frequent recalibration events to maintain reliability while imposing minimal operational constraints.
Solution Approach 2:
The battery management system performs self-calibration by automatically detecting when the battery reaches a predetermined charge value during normal operation and autonomously resetting the SOC estimation algorithm. This self-service approach eliminates the need for external intervention or specialized recalibration procedures, allowing frequent recalibration without increasing operational constraints.
Data Source
AI summary
The invention relates to a method for detecting a particular predetermined value (QA) of the charge contained in a first elementary cell of a battery, comprising the following steps: measuring the voltage across the cell under a reference current at several times during a charging or discharging phase of the cell between first and second state-of-charge levels; and detecting a particular predetermined value (UA) of this voltage, corresponding to the particular charge value (QA).