Battery Cell Impedance Monitoring for Sensorless Temperature Tracking
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Solution Overview
Problem
Existing electrical energy storage systems in vehicles face challenges in efficiently and reliably managing the temperature of individual storage cells, which affects their service life and performance capability.
Innovation Solution
A device and method for monitoring the temperature of storage cells using impedance measurements, without the need for dedicated temperature sensors, by applying alternating current and analyzing impedance values against characteristic data to estimate cell temperatures and detect deviations indicative of temperature control system malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated temperature sensors are installed in each storage cell, then temperature monitoring precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses impedance as an intermediary parameter to indirectly measure temperature. Instead of directly measuring temperature with sensors, the system measures electrical impedance of storage cells and converts these impedance values to temperature readings through calibration curves, thereby avoiding direct temperature sensor installation while achieving accurate monitoring
Solution Approach 2:
The patent replaces the physical temperature sensing mechanism with an electrical measurement mechanism. By applying alternating current and measuring impedance, the system substitutes mechanical/thermal contact-based temperature sensing with non-contact electrical field-based measurement, reducing device complexity
2Device complexity
If impedance measurements are used to monitor temperature, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The patent performs preliminary calibration by establishing impedance-temperature characteristic curves before actual operation. During normal monitoring, pre-stored calibration data at multiple temperatures are used to convert measured impedance values to accurate temperature readings, ensuring measurement precision is maintained
Solution Approach 2:
The patent measures impedance at multiple different alternating current frequencies to capture the frequency-dependent behavior of storage cells. By analyzing impedance changes across different frequencies, the system extracts more accurate temperature information and compensates for other variable effects
3Reliability
If multiple subsets of storage cells are monitored, then reliability of temperature management is improved, but measurement time and processing complexity increase
Solution Approach 1:
The patent divides the large number of storage cells into multiple subsets, where each subset contains P storage cells connected in parallel. By monitoring a representative subset rather than every individual cell, the system achieves reliable temperature management while reducing measurement burden and processing time
Solution Approach 2:
The patent uses the same impedance measurement apparatus and method to monitor multiple storage cell subsets simultaneously. The universal measurement approach allows efficient parallel monitoring of all subsets using identical equipment, reducing overall measurement time while maintaining comprehensive coverage
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 efficient and accurate temperature monitoring of storage cells, allowing for timely detection of temperature control issues and improving the service life and performance of the energy storage system.
Implementation Method 1
determine M measured values of an impedance of the M storage cell subsets
Data Source
AI summary
A device and method for monitoring the temperature of an energy storage unit having M subsets of P storage cells, where M≥1 and/or P≥1, is provided. The P storage cells are arranged electrically in parallel with one another, and the M subsets are arranged electrically in series. The device is configured to determine M measured values of the impedance of the corresponding M subsets of P storage cells and to monitor the temperature of the energy storage unit based on the M measured values of the impedance.