Zero-Phase Resistance Calculation for Battery Internal Impedance
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Solution Overview
Problem
Existing methods for determining the internal resistance of energy accumulators require significant excitation or complex hardware, making them inefficient and impractical for hybrid and electric vehicles without a classic engine start, and are sensitive to fluctuations and faulty measurements.
Innovation Solution
A method that calculates zero-phase resistance by analog to digital conversion, band-pass filtering, and checking specific prerequisites, allowing for passive determination using minimal computational work and valid measurements, and optionally low-pass filtering for noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong excitation of the electrical energy accumulator is used to ascertain internal resistance, then the internal resistance can be determined, but the method becomes impractical for hybrid and electric vehicles without a classic engine start
Solution Approach 1:
The patent changes the excitation parameter from strong (engine start) to weak (small current or voltage fluctuations). By using weak excitation signals and processing them through band-pass filtering around the zero-phase frequency, the system can determine internal resistance without requiring strong excitation, making it applicable to hybrid and electric vehicles without a classic engine start.
2Device complexity
If passive ascertainment with uncontrolled excitation is used, then hardware demands are reduced, but the internal resistance is not updated when calculation prerequisites are not satisfied
Solution Approach 1:
The patent implements a feedback mechanism through continuous monitoring of calculation prerequisites (filter initialization, peak current detection, threshold current satisfaction, peak voltage detection, and sign consistency). When these prerequisites are satisfied, the internal resistance is updated; when not satisfied, the system continues monitoring without updating, ensuring reliability while maintaining simple hardware requirements.
3Reliability
If spectral method with discrete Fourier transformation is used to determine internal resistance, then the internal resistance can be ascertained, but the computational work is significantly higher
Solution Approach 1:
The patent extracts only the essential information needed for internal resistance determination by using band-pass filtering around the zero-phase frequency to isolate the relevant signal components. This approach takes out only the necessary frequency components rather than performing a complete discrete Fourier transformation, significantly reducing computational work while maintaining determination reliability.
4Productivity
If active determination with controlled alternating voltage is used, then the internal resistance can be calculated continuously, but complex hardware with power electronics is required and the battery is loaded
Solution Approach 1:
The patent enables the electrical energy accumulator to serve itself by using its own operational fluctuations (current or voltage variations during driving or engine off states) as excitation signals. This self-service approach eliminates the need for complex external power electronics while maintaining calculation continuity, as the system processes the naturally occurring signals during normal operation.
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 and efficient calculation of internal resistance without interruption or mains voltage dependency, suitable for embedded systems, and adaptable to varying precision and noise, ensuring reliable results.
Implementation Method 1
b. Filtering of the digital voltage values and the digital current values with the aid of a band-pass filter around the zero-phase frequency in order to obtain filtered voltage values and current values
Data Source
AI summary
A method is described for ascertaining an internal resistance of an electrical energy accumulator. For this purpose, an analog voltage signal and an analog current signal are subjected to an analog to digital conversion and subsequently to band-pass filtering in order to obtain filtered voltage values and filtered current values. These are then checked with regard to different calculation prerequisites, whereupon a zero-phase resistance is calculated. Then, the calculated zero-phase resistance is supplied as internal resistance.