Traction Battery Internal Short Circuit Detection via dV/dt and dAh/dt
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Solution Overview
Problem
Existing methods fail to effectively detect and prevent thermal issues caused by internal short circuit resistances in automotive traction batteries, as they either result in false positives or insufficient action, and voltage-based detections are inadequate for identifying such conditions.
Innovation Solution
The implementation of model predictive control using a deep neural network to calculate and predict the rate of voltage change per amp hour increase, with thresholds to confirm the presence of internal short circuit resistances, and a controller to prevent power flow from the battery to the electric machine when such conditions are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If voltage-based detection methods are used to identify internal short circuit resistances, then the detection process is simple, but the detection precision is insufficient and results in false positives
Solution Approach 1:
The patent changes the detection parameter from simple voltage measurement to a composite parameter combining voltage change rate (dV/dt) and amp hour change rate (dAh/dt). This parameter transformation enables more precise detection of internal short circuit conditions by capturing the dynamic relationship between voltage and charge accumulation, thereby resolving the contradiction between simple detection and accurate detection.
2Device complexity
If existing detection methods are used, then the device complexity is low, but the reliability of detecting internal short circuits is insufficient
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors dV/dt and dAh/dt, compares them against threshold values, and adjusts the contactor state accordingly. When the voltage change rate exceeds the threshold while amp hour change remains within normal limits, the system feedbacks a detection signal to open the contactor, preventing further charging. This closed-loop feedback ensures reliable detection and response to internal short circuit conditions without requiring complex additional hardware.
3Device complexity
If no detection system is implemented, then the device complexity is minimal, but thermal issues from internal short circuits cannot be prevented
Solution Approach 1:
The patent applies preliminary action by detecting internal short circuit conditions before they lead to severe thermal damage. The system proactively monitors the battery during charging, calculates dV/dt and dAh/dt in real-time, and opens the contactor preemptively when abnormal patterns are detected. This preliminary detection and response mechanism prevents thermal runaway and battery damage while maintaining relatively simple system architecture through the use of existing sensor data and computational logic.
Data Source
AI summary
A controller selectively prevents electrical power flow from a traction battery to an electric machine based on an actual rate of charge acquired by a cell of the traction battery per unit of actual increase in amp hours and an expected rate of charge acquired per unit of expected increase in amp hours.