EV Battery Take-Off Control Using Thermal Activity State
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Solution Overview
Problem
Existing battery management systems in electric vehicles often unnecessarily disconnect the battery energy storage system due to high temperatures, leading to prolonged vehicle inactivity, especially in hot climate areas, as they fail to differentiate between ambient heating and thermal activity heating.
Innovation Solution
A computer system that determines the battery temperature and ambient temperature to calculate a thermal activity state, preventing take-off only when the thermal activity state exceeds a predetermined threshold, allowing take-off if the battery temperature is above a threshold but the thermal activity state is not, and optionally requesting increased cooling for safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery management system disconnects the battery energy storage system when the battery temperature exceeds the maximum safety temperature, then the safety of the battery system is improved, but the vehicle usability deteriorates due to prolonged inactivity
Solution Approach 1:
The patent changes the parameter used for safety assessment from absolute battery temperature to thermal activity state (temperature difference between battery and ambient). This allows the system to maintain safety by detecting actual thermal conditions while avoiding unnecessary disconnections when high battery temperature is caused by hot ambient conditions rather than excessive thermal activity
Solution Approach 2:
The system dynamically adjusts the disconnection decision based on the thermal activity state calculation. By continuously monitoring the temperature difference and comparing it to a threshold, the system adapts its safety response to the actual thermal conditions, preventing premature disconnections while maintaining protection against genuine thermal risks
2Device complexity
If the battery management system uses absolute battery temperature threshold for disconnection, then the safety protection is simplified, but the accuracy of thermal condition assessment deteriorates
Solution Approach 1:
The patent introduces a new parameter (thermal activity state = battery temperature - ambient temperature) that transforms the absolute temperature measurement into a relative thermal condition indicator. This maintains the simplicity of threshold-based control while significantly improving the accuracy of thermal condition assessment by accounting for ambient temperature effects
Data Source
AI summary
A computer system is provided. The computer system includes a processor device configured to determine a requested take-off of a parked electric vehicle; determine a battery temperature of at least one battery cell of the electric vehicle; determine an ambient temperature of the electric vehicle; determine a thermal activity state of at least one battery cell as the difference between the battery temperature and the ambient temperature; and prevent the requested take-off when the thermal activity state is above a predetermined thermal activity state threshold.