Battery SoC Monitoring via Electrical and Mechanical Phase Difference
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Solution Overview
Problem
Current State-of-Health (SoH) monitoring techniques for electrochemical energy devices, such as batteries, are inadequate due to variability introduced by factors like internal impedance build-up, temperature, and manufacturing tolerances, leading to inaccurate capacity and lifetime predictions, and necessitate costly and time-consuming test discharges.
Innovation Solution
A method and device that apply both electrical and mechanical excitations to measure phase differences between voltage and current, allowing for real-time, empirical determination of SoH, thereby compensating for internal impedance and other factors to provide accurate SoC and lifetime predictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional EIS monitoring techniques are used, then the measurement process is simple, but the measurement precision is low due to variability from internal impedance build-up, temperature, and manufacturing tolerances
Solution Approach 1:
The patent applies mechanical vibration or ultrasonic excitation to the battery in addition to electrical excitation. This mechanical energy input helps to agitate the electrolyte and reduce the effects of ionic kinetic limitations, thereby improving the accuracy of EIS measurements without significantly increasing system complexity
Solution Approach 2:
The patent measures EIS at multiple frequency points and uses the phase difference between voltage and current responses to determine SoH. By changing the measurement parameters (frequency, excitation type) and analyzing the differential response, the system achieves higher measurement precision while managing complexity through algorithmic processing
2Measurement precision
If frequent test discharges are performed to accurately determine battery capacity, then the measurement precision improves, but the loss of time and productivity increase significantly
Solution Approach 1:
The patent replaces the mechanical/electrical test discharge process with an EIS-based measurement system that uses electrical excitation and phase difference analysis. This substitution eliminates the need for time-consuming discharge tests while providing accurate capacity and SoH information through non-intrusive electrical measurements
Solution Approach 2:
The monitoring system performs measurements during normal battery operation without requiring separate test cycles. The battery continues its normal charge/discharge cycles while the EIS measurements are taken during idle moments, allowing the system to monitor itself without external intervention or operational disruption
3Reliability
If internal impedance build-up is not compensated for, then the device complexity remains low, but the reliability of SoC monitoring deteriorates over time
Solution Approach 1:
The patent uses the measured phase difference and EIS parameters as feedback to continuously update and adjust the SoC estimation. By monitoring changes in internal impedance over time and feeding this information back into the monitoring algorithm, the system compensates for aging effects and maintains reliable measurements throughout the battery lifecycle
Solution Approach 2:
The system establishes a baseline EIS signature when the battery is new and uses this as a reference for comparing future measurements. By having the preliminary characterization data available before degradation occurs, the system can detect and compensate for changes in internal impedance, maintaining reliability without requiring complex real-time adjustment mechanisms
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 enables accurate, real-time monitoring of battery health, reducing the need for frequent test discharges, improving battery management systems, and extending the life and performance of energy storage devices.
Implementation Method 1
Electrochemical impedance spectroscopy (EIS) has been used in studies of electrode and plate behavior during charging and discharging
Implementation Method 2
The impedance response of the battery depends on the measurement frequency and the state of the energy device
Implementation Method 3
applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency
Data Source
AI summary
A device and associated testing method for empirically determining the state-of-charge of an electrochemical energy device, comprising: applying electrical excitations to the energy device at a predetermined electrical excitation frequency ωe; applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency ωm; measuring an electrically-induced phase difference Δθe(ωe) between voltage (V) and current (I) within the energy device from applying the electrical excitations; measuring a mechanically-induced phase difference Δθe(ωm) between voltage (V) and current (I) within the energy device from applying the mechanical excitations; and deducing the empirical real-time state-of-health of the energy device by comparing the electrically-induced phase difference Δθe(ωe) with the mechanically-induced phase difference Δθe(ωm); and using the deduced state of health to determine the state of charge.