Traction Battery Tab Temperature Estimation for Power Derating
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Solution Overview
Problem
Existing methods for estimating battery cell tab temperature in electric vehicles are impractical due to the need for numerous temperature sensors, which is costly and inefficient, especially when direct measurement of each cell tab is not feasible.
Innovation Solution
A system and method that estimate battery cell tab temperature using a thermal model based on measured battery temperature, resistance of cell tabs, and thermal resistivity, adjusting power output from the traction battery according to current, temperature, and distance between measurement and tab locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerous temperature sensors are deployed to directly measure each cell tab temperature, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent introduces an intermediary thermal model that uses easily measurable parameters (battery temperature, resistance, current, distance) to indirectly estimate cell tab temperature. This mediator approach avoids direct sensor placement on each cell tab while achieving accurate temperature estimation through thermal relationship calculations.
Solution Approach 2:
Instead of directly measuring each cell tab temperature with physical sensors, the patent creates a thermal model that copies the thermal behavior of cell tabs using measurements from accessible locations. The model replicates the temperature characteristics through mathematical relationships, eliminating the need for physical sensor copies at each cell tab.
2Measurement precision
If direct measurement of each cell tab is implemented, then measurement precision is improved, but ease of operation deteriorates due to infeasibility
Solution Approach 1:
The thermal model acts as an intermediary that translates easily obtainable measurements (battery temperature from external sensors, resistance from electrical measurements, current from power management) into cell tab temperature estimates. This mediator approach makes the measurement process feasible by using accessible parameters rather than requiring direct cell tab access.
Solution Approach 2:
The patent replaces the mechanical/physical measurement system (direct sensor placement on cell tabs) with a computational/thermal model system. Instead of physically touching or accessing each cell tab with sensors, the system uses mathematical modeling and thermal relationships to estimate temperatures, substituting complex physical measurement with computational analysis.
3Reliability
If power output is reduced proactively based on temperature estimation, then reliability is improved by preventing overheating, but power output decreases
Solution Approach 1:
The system performs preliminary temperature estimation and proactive power mitigation before critical overheating conditions occur. By continuously monitoring estimated cell tab temperatures and reducing power output in advance when temperature trends indicate potential overheating, the system prevents reliability issues before they manifest, rather than reacting after problems occur.
Solution Approach 2:
The patent implements a feedback control loop where estimated cell tab temperatures continuously inform power management decisions. The thermal model provides real-time temperature estimates that feed back to the power control system, which adjusts power output accordingly. This closed-loop feedback ensures reliability by automatically responding to temperature conditions while optimizing power delivery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate estimation of cell tab temperature without extensive sensor deployment, allowing for proactive power mitigation strategies to prevent overheating, thereby ensuring efficient and safe battery operation.
Implementation Method 1
The cell tabs may conduct heat away from the battery cells to other components of the battery pack
Implementation Method 2
The controller may determine that the cell tab temperature exceeds the maximum allowable cell tab temperature based on the cell temperature, the resistance of the cell tabs, and the temperature difference between the battery cells and the cell tabs
Data Source
AI summary
A power system for a vehicle includes a controller that alters an amount of power output from a traction battery according to a magnitude of current passing through a tab of a cell of the traction battery, a temperature, and a distance between a location at which the temperature is measured and the tab.