Battery Pack Internal Short Detection via Voltage Pattern Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery packs for electric vehicles face challenges in detecting and responding to internal short circuits that lead to sustained high currents below the maximum operating current, causing component overheating and potential hazards, as current protection devices are either ineffective or expensive.
Innovation Solution
A system and method that utilize voltage and current data to detect potentially hazardous over-currents due to internal short circuits, independent of the response, which includes a sensor system, controller, and remediation system to manage and mitigate excessive thermal conditions by monitoring and responding to over-current internal shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional short circuit protection devices are used, then high current protection is achieved, but they are ineffective for sustained high currents below maximum operating current
Solution Approach 1:
The patent changes the detection parameter from current-only to voltage-based detection. By monitoring voltage drops across battery cells and comparing them to threshold values, the system can detect internal short circuits that cause sustained high currents below maximum operating current, which traditional current-based protection devices miss.
Solution Approach 2:
The patent replaces traditional mechanical/electrical protection devices (fuses, circuit breakers) with an electronic control system that uses voltage sensing and comparison circuits. This substitution enables detection of subtle voltage changes that indicate internal shorts, providing protection in the previously undetected current range.
2Reliability
If fuses with long thermal time constant are used to protect against sustained high current, then protection coverage is improved, but cost and weight increase
Solution Approach 1:
The patent replaces heavy thermal-mass-based protective devices (long time constant fuses) with lightweight electronic voltage monitoring circuitry. The control system detects internal shorts by comparing voltage drops to predetermined thresholds and can interrupt current flow through contactors, achieving the same protection coverage without the weight and cost of specialized fuses.
Solution Approach 2:
The patent uses voltage drop measurements as a proxy indicator for internal short conditions. Instead of directly measuring current or using thermal mass to detect overheating, the system copies the effect of internal shorts through voltage changes, enabling indirect detection and response to sustained high current conditions.
3Measurement precision
If voltage and current data are monitored and analyzed, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The patent simplifies monitoring by changing from multi-parameter analysis (voltage and current) to single-parameter voltage-based detection. By focusing solely on voltage drop across battery cells and comparing to predetermined thresholds, the system achieves accurate internal short detection without the complexity of analyzing multiple parameters simultaneously.
Solution Approach 2:
The patent divides the battery pack into individual cell monitoring units, each with its own voltage sensing and comparison logic. This segmentation allows distributed detection across all cells without requiring a centralized complex analysis system, reducing overall system complexity while maintaining high detection accuracy.
Data Source
AI summary
A controller identifies a condition of a hazardous internal short by comparing patterns of series element voltages to the last known balance condition of the series elements. If the loaded or resting voltage of one or more contiguous series elements uniformly drop from the previously known condition by an amount consistent with an over-current condition, an over-current internal short circuit fault is registered. The desired response is to prevent the affected series elements from heating to a hazardous temperature by summoning the maximum heat rejection capability of the system until the short ceases and the affected elements cool, the cooling function is no longer able to operate due to low voltage, or the affected series string has drained all of its energy through the short. Also includes are responses that allow the battery pack to continue to power the cooling system even though it may enter an over-discharged state.