Battery Module FPCB Layout for Accurate End-to-End Temperature Sensing
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Solution Overview
Problem
In battery modules with long cells, temperature deviations along the longitudinal direction can lead to inaccurate temperature sensing, resulting in potential safety issues and energy density loss.
Innovation Solution
The battery module incorporates temperature sensors installed at both longitudinal ends of the cell stack, with a FPCB assembly that includes a first FPCB extending along the cell stack and a second FPCB connected to bus bars, ensuring accurate temperature measurement without significant structural modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature sensor is installed in a battery module with long cells, then the device complexity is low, but the measurement precision deteriorates due to temperature deviation along the longitudinal direction
Solution Approach 1:
The battery module divides the temperature monitoring function into multiple segments by installing temperature sensors at both longitudinal ends of the cell stack. This segmentation allows each sensor to accurately measure the temperature at its specific location, and the BMS integrates these measurements to determine the maximum temperature, thereby resolving the measurement inaccuracy caused by using a single sensor.
Solution Approach 2:
The patent transitions from a single-point temperature measurement approach to a multi-point distributed measurement approach along the longitudinal dimension of the cell stack. By adding the longitudinal dimension of temperature monitoring at both ends, the system captures temperature variations that exist along the length of long cells, significantly improving measurement precision without excessive complexity.
2Measurement precision
If the temperature sensor is positioned away from the cell stack, then the ease of operation is improved, but the measurement precision deteriorates due to distance from the heat source
Solution Approach 1:
The FPCB assembly is designed with a local temperature sensor placing portion that provides optimal thermal contact with the cell stack at the longitudinal ends. This localized design ensures high measurement precision at the hottest spots while the flexible FPCB structure allows the sensor to be positioned exactly where needed, balancing measurement accuracy with installation feasibility.
3Measurement precision
If the battery module structure is significantly modified to improve temperature sensing, then the measurement precision is improved, but the productivity deteriorates due to increased manufacturing complexity
Solution Approach 1:
The FPCB assembly serves multiple functions simultaneously: it provides electrical connections through bus bars, structural support for temperature sensors, thermal contact with the cell stack, and mechanical stability. This multi-functionality allows the system to achieve improved temperature sensing precision without adding separate components or significantly modifying the existing battery module structure, thereby maintaining productivity.
4Measurement precision
If additional components are added to the battery module for accurate temperature sensing, then the measurement precision is improved, but the energy density deteriorates due to increased volume
Solution Approach 1:
The patent merges the temperature sensing function with the existing FPCB and bus bar structure. By integrating temperature sensors onto the FPCB assembly that already serves electrical connection purposes, the system achieves accurate temperature measurement at both longitudinal ends without adding significant volume or separate components, thereby minimizing the impact on energy density.
Data Source
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AI summary
Disclosed is a battery module, which includes a cell stack formed by stacking a plurality of battery cells; a bus bar frame assembly including a bus bar frame configured to cover one longitudinal end and the other longitudinal end of the cell stack and a plurality of bus bars fixed on the bus bar frame and electrically connected to the battery cells; and a FPCB assembly including a first FPCB extending along a longitudinal direction of the cell stack to cover at least a portion of an upper surface of the cell stack, a second FPCB extending from both longitudinal ends of the first FPCB and electrically connected to the bus bars, and a pair of temperature sensors mounted to both longitudinal ends of the first FPCB.