Battery Cell State Tracking Using Cross-Cell Voltage Reference
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Solution Overview
Problem
Existing methods for determining the state of a battery cell provide only snapshots without tracking the development of the state over its lifetime, failing to enable early detection of failures and timely servicing.
Innovation Solution
A method involving charging and discharging processes to determine discharge and charging voltages, normalizing these voltages relative to other cells, and calculating state parameters like capacity and equilibrium parameters to track the cell's state development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only snapshot measurements are taken for cell state determination, then the measurement process is simple, but the ability to track state development over lifetime is lost
Solution Approach 1:
The patent establishes a reference state at the beginning of battery operation (new battery state) by measuring open-circuit voltages after individual cell discharges. This preliminary reference data enables subsequent comparison with current cell states to detect degradation and failures over time, allowing early intervention before complete failure occurs.
Solution Approach 2:
The patent implements continuous monitoring by repeatedly measuring cell voltages during charging/discharging cycles and comparing them against the reference state. This feedback mechanism tracks the development of cell states over time, identifying cells that deviate from expected behavior and enabling timely servicing.
2Measurement precision
If individual cell states are determined without considering other cells, then the measurement process is simpler, but the ability to identify relative cell degradation is reduced
Solution Approach 1:
The patent applies individual discharge procedures to each cell to determine its specific open-circuit voltage and state. By treating each cell locally with its own reference measurement and evaluation, the method captures cell-specific characteristics and degradation patterns while maintaining overall system coherence through comparison with other cells.
Solution Approach 2:
The patent divides the battery into individual cells, each undergoing separate discharge and measurement procedures. This segmentation allows independent determination of each cell's state and reference values, enabling precise identification of which specific cell is degrading or failing without being masked by other cells' performance.
3Reliability
If continuous monitoring of all cells is implemented, then early detection of failures is enabled, but the complexity and cost of the monitoring system increases
Solution Approach 1:
The patent performs complete reference measurements and individual cell discharges only when necessary - such as when a cell shows signs of degradation or at scheduled intervals - rather than continuously for all cells. This partial application of the full measurement procedure reduces system complexity while maintaining the ability to detect failures through comparison with the reference state.
Data Source
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AI summary
Method for determining a state of each of a plurality of cells (1, 2, 3, 4) of a battery (5); at least comprising the following steps: a) carrying out a charging operation (6) or a discharging operation (7) of the cells (1, 2, 3, 4); b) determining a discharge voltage (8) of each of the cells (1, 2, 3, 4) and a charging voltage (9) of each of the cells (1, 2, 3, 4); c) determining at least one state parameter (10, 11) for each cell (1, 2, 3, 4), wherein the state parameter is derived from the discharge voltage (8) and the charging voltage (9), wherein a discharge voltage (8) and a charging voltage (9) of at least one other cell (4, 3, 2, 1) is taken into account for the state parameter.