Battery Impedance Detection Using Dual Measurement Circuits
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Solution Overview
Problem
Existing methods for reliably measuring the impedance of batteries, such as lithium-ion batteries, face challenges due to measurement errors introduced by non-identical gain and phase shifts in measurement circuits, which affect the accuracy of impedance detection.
Innovation Solution
A method involving driving an alternating current into a battery, measuring voltage and current using different measurement circuits, calculating a preliminary impedance, and correcting for gain and phase errors to obtain an accurate battery impedance value, which can be achieved by calculating the quotient of current measurement values or using a product and square root of impedance values to mitigate measurement circuit errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage and current measurements are performed using different measurement circuits, then impedance detection can be performed, but measurement errors are introduced due to non-identical gain and phase shifts in the circuits
Solution Approach 1:
The system performs measurements using both measurement circuits and uses the results from one circuit to correct errors in the other circuit. Specifically, impedance values or current measurement values obtained from one circuit are used as feedback to compensate for gain and phase errors in the other circuit, thereby improving overall measurement accuracy while maintaining the ability to perform impedance detection.
Solution Approach 2:
The system changes the operating parameters of the measurement circuits by adjusting gain and phase shift values based on measured data. By dynamically modifying these parameters using correction factors derived from comparative measurements, the system compensates for circuit mismatches and achieves accurate impedance measurements despite using non-identical measurement circuits.
2Adaptability or versatility
If measurement circuits with different gain and phase characteristics are used, then the system can operate with flexible circuit design, but the accuracy of impedance detection deteriorates
Solution Approach 1:
The system dynamically adjusts the gain and phase parameters of the measurement circuits based on actual measurements. By calculating correction factors from comparative measurements and applying these to modify circuit parameters, the system maintains measurement accuracy despite using circuits with different inherent characteristics, thus preserving design flexibility without sacrificing precision.
Solution Approach 2:
The system uses feedback mechanisms where measurement results from one circuit inform the adjustment of the other circuit's parameters. This closed-loop approach allows the system to adapt to the specific characteristics of each circuit, compensating for their differences and maintaining accurate impedance detection across various circuit configurations.
Data Source
AI summary
A method is disclosed, which includes driving an alternating input current into a battery, measuring a voltage across the battery by a first measurement circuit to obtain a voltage measurement value, measuring a current through the battery by a second measurement circuit to obtain a current measurement value, and measuring a current through the battery using the first measurement circuit to obtain a further current measurement value. Further, the method includes calculating an impedance of the battery based on the current measurement value, the further current measurement value, and the voltage measurement value.