Battery Temperature Detection via Impedance Intercept Frequency
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Solution Overview
Problem
Existing sensor-less battery temperature detection methods, such as ZIF and NZIF, are time-consuming and prone to noise interference, especially at low frequencies, making them unreliable for high-quality automotive batteries.
Innovation Solution
A method that calculates an intercept frequency where the imaginary part of the battery impedance equals a predefined value based on measurements at two different frequencies, reducing the need for multiple frequency measurements and minimizing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ZIF method is used to detect battery temperature, then temperature detection can be performed, but measurements at low frequencies are affected by noise interference making them unreliable
Solution Approach 1:
The patent introduces an intermediary calculation step that uses imaginary part measurements at two different frequencies to compute the intercept frequency indirectly. Instead of directly measuring at the problematic low ZIF frequency, the method uses higher frequencies where noise is reduced, processes the data through a calculation intermediary (equation involving imaginary parts and frequencies), and obtains the temperature. This intermediary approach transfers the measurement from noisy low-frequency direct detection to cleaner high-frequency indirect detection.
2Measurement precision
If multiple frequency measurements are performed in ZIF or NZIF methods, then temperature detection can be achieved, but the process becomes time consuming
Solution Approach 1:
The patent extracts only the essential information needed for temperature detection by measuring the imaginary part of impedance at just two specific frequencies, rather than performing comprehensive multi-frequency sweeps. The method extracts the temperature-relevant data points (imaginary parts at two frequencies) and discards unnecessary measurements, thereby reducing measurement time while maintaining sufficient accuracy for temperature determination through the intercept frequency calculation.
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
This approach allows for faster and more reliable battery temperature detection by extrapolating the intercept frequency from two measurements, thereby reducing the impact of noise and improving measurement efficiency.
Implementation Method 1
the imaginary part of the battery impedance is dependent on the temperature in such a way that at a given temperature the imaginary part of the battery impedance of batteries of a certain type intercepts zero at essentially the same frequency
Data Source
AI summary
A method and a temperature detection circuit are disclosed. An example of the method includes driving an alternating current with a first frequency into a battery and detecting an imaginary part of a battery impedance at the first frequency; driving an alternating current with a second frequency different from the first frequency into the battery and detecting an imaginary part of the battery impedance at the second frequency; and calculating an intercept frequency at which the imaginary part equals a predefined value at least based on the imaginary part obtained at the first frequency and the imaginary part obtained at the second frequency.