Battery Cell State Tracking Through Cross-Cell Voltage Comparison
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Solution Overview
Problem
Existing methods for determining the state of a battery cell provide only snapshots, failing to detect the evolution of the state over its service life, which can lead to unexpected failures during operation.
Innovation Solution
A method involving charging and discharging operations to determine discharge and charge voltages of each cell, normalizing these voltages relative to other cells, and calculating state parameters like capacity and equilibrium parameters to track the evolution of cell state over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snapshot-based state determination methods are used, then the measurement process is simple, but the ability to detect state evolution over service life is lost
Solution Approach 1:
The patent applies preliminary action by storing reference voltage values (charge voltages and discharge voltages) from multiple charging/discharging cycles before state determination. These pre-stored reference values from previous cycles are used to calculate state parameters, enabling evolution detection without requiring complex real-time comparison systems. The reference values are accumulated in advance to establish a baseline for detecting changes over service life.
2Loss of information
If only individual cell voltages are measured, then the measurement process is simple, but information on relative state differences between cells is lost
Solution Approach 1:
The patent transforms individual cell voltage measurements into meaningful state parameters by calculating differences between charge voltages and discharge voltages, and by comparing voltages across multiple cells. This parameter transformation converts raw voltage data into state parameters (e.g., state of charge, health indicators) that reveal relative state differences. The method changes the parameter representation from absolute voltages to differential state parameters, enabling detection of relative cell conditions without adding measurement complexity.
3Measurement precision
If frequent state measurements are performed, then the temporal resolution of state evolution is improved, but the energy consumption and operational disruption increase
Solution Approach 1:
The patent enables continuous state monitoring by utilizing voltage measurements that are naturally obtained during normal charging and discharging operations. Instead of requiring separate dedicated measurement cycles that would interrupt operation and consume additional energy, the system continuously accumulates voltage data from routine battery use. This approach maintains measurement continuity and temporal resolution while avoiding extra energy expenditure, as the useful action of charging/discharging serves dual purposes: battery operation and state monitoring.
Data Source
AI summary
A method for determining a respective state of each of a plurality of cells of a battery, comprising at least the following steps: a) carrying out a charging operation or a discharging operation on the cells; b) determining a discharge voltage of each of the cells and a charge voltage of each of the cells; c) determining at least one state parameter for each cell, wherein the state parameter is derived from the discharge voltage and the charge voltage, wherein a discharge voltage and a charge voltage of at least one other cell is taken into account for the state parameter.