Battery Cell Fault Detection via Dynamic Voltage-Current Plausibility
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Solution Overview
Problem
Existing detection methods for faults in energy storage cells of electrical energy stores in motor vehicles are inefficient and costly due to the need for additional sensor apparatuses and set-point value adjustments, especially in parallel interconnections where voltage responses are compensated.
Innovation Solution
A detection device using current and voltage sensors to temporarily store and compare dynamic curves of current and cell voltage values over a predetermined time period, detecting faults by analyzing the gradient alignment between these curves without relying on additional sensor data or set-point values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional sensor apparatuses (temperature, pressure, light sensors) are added to detect fault features, then the detection capability and reliability improve, but the costs and weight of the electrical energy store increase
Solution Approach 1:
The patent combines temperature, pressure, and light sensor data with existing voltage and current measurements into a unified detection system. The evaluation unit integrates multiple sensor inputs to comprehensively assess cell health, replacing the need for separate independent detection systems and reducing overall system weight.
Solution Approach 2:
The evaluation unit is designed to process data from multiple sensor types (voltage, current, temperature, pressure, light) and perform multiple detection functions including cell fault detection, thermal runaway prediction, and state of charge estimation. This multi-functional approach eliminates the need for separate dedicated systems for each detection function.
2Reliability
If additional sensor apparatuses are added to detect fault features, then the detection capability improves, but the costs of the electrical energy store increase
Solution Approach 1:
The patent consolidates multiple detection functions into a single evaluation unit that processes data from various sensors. By sharing common processing infrastructure and data buses, the system reduces the number of separate components needed, thereby lowering manufacturing costs while maintaining comprehensive detection capability.
Solution Approach 2:
The evaluation unit performs multiple detection functions (voltage monitoring, current monitoring, temperature detection, pressure detection, light detection, and fault analysis) through a single integrated system. This multi-functionality reduces the total component count and simplifies manufacturing processes.
3Measurement precision
If voltage set-point values are adjusted over time to account for aging-related changes, then the accuracy of fault detection is maintained, but the device complexity and need for calibration increase
Solution Approach 1:
The system performs preliminary characterization of each cell's voltage response to current changes during normal operation and stores this data for future reference. This pre-established baseline allows the system to detect deviations indicating faults without requiring continuous recalibration or adjustment of set-point values.
Solution Approach 2:
The evaluation unit continuously monitors the relationship between current changes and voltage responses, comparing actual measurements against stored reference data. When deviations exceed thresholds, the system triggers fault detection and alerts, providing continuous feedback without requiring manual intervention or recalibration.
4Ease of operation
If voltage response comparison with set-point values is used to detect defective cells, then the detection method is simple, but faults cannot be detected in parallel interconnections due to voltage compensation by other cells
Solution Approach 1:
The system establishes reference data during normal operation that captures the expected voltage response of each cell to current changes. This preliminary characterization creates a unique fingerprint for each cell, enabling individual cell monitoring even in parallel configurations where voltage compensation occurs.
Solution Approach 2:
Instead of relying solely on voltage magnitude comparisons, the system analyzes the dynamic relationship between current changes and voltage responses over time. By examining the temporal dimension of the voltage-current relationship, the system can detect cell faults that are masked by voltage compensation in parallel interconnections.
Data Source
AI summary
A detection device for an electrical energy store of a motor vehicle for detecting a fault of at least one energy store cell of a circuit of energy storage cells of the energy store includes a current sensor for detecting current values of the circuit, a voltage sensor for detecting cell voltage values of the energy store cells, and a storage and evaluation apparatus to receive and temporarily store the current and cell voltage values over a predefined time span, to compare a dynamic of cell voltage profiles obtained from the temporarily stored cell voltage values of a time span with a dynamic of the current profile obtained from the temporarily stored current values of the time span, and to detect, on the basis of the comparison, a fault of at least one energy store cell.