Battery Impedance Mapping for Temperature, SoC, and SoH Estimation
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Solution Overview
Problem
Existing battery management systems face challenges in accurately determining critical states such as temperature, state of charge (SoC), and state of health (SoH) due to the complexity of battery chemistries, which are essential for safe and efficient operation, especially in applications like electric vehicles.
Innovation Solution
A method and apparatus utilizing electrochemical impedance spectroscopy (EIS) to measure impedance features across a range of frequencies, transforming these measurements into the frequency domain to estimate battery states, and employing functional mappings to determine temperature, SoC, and SoH based on impedance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional battery management systems are used to determine battery states, then the system structure is simple, but the measurement precision of temperature, state of charge, and state of health is insufficient
Solution Approach 1:
The patent replaces traditional mechanical/electrical measurement systems with electrochemical impedance spectroscopy (EIS) technology. By applying small AC voltage signals across a frequency range and measuring the resulting current responses, the system extracts impedance features that correlate with battery states (temperature, SoC, SoH), achieving higher measurement precision without significantly increasing system complexity
Solution Approach 2:
The patent changes the measurement parameter from simple voltage/current to frequency-dependent impedance characteristics. By sweeping through multiple frequencies and analyzing the impedance spectrum, the system obtains richer information about battery internal states, improving estimation accuracy through parameter transformation
2Measurement precision
If electrochemical impedance spectroscopy is used to measure impedance features, then the state estimation precision is improved, but the use of energy and time for measurement increases
Solution Approach 1:
The patent applies partial action by selecting specific frequency ranges and impedance features that are most informative for state estimation. Instead of measuring the entire frequency spectrum uniformly, the system focuses on critical frequency regions where impedance characteristics provide maximum insight into battery states, reducing measurement time while maintaining precision
Solution Approach 2:
The patent performs preliminary action by pre-processing the impedance data to extract key features before full state estimation. The system identifies characteristic frequencies and impedance patterns in advance, allowing for faster state determination during operation without requiring complete frequency sweeps each time
3Measurement precision
If electrochemical impedance spectroscopy is used to measure impedance features, then the state estimation precision is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the EIS measurement system to serve multiple functions: it simultaneously estimates temperature, state of charge, and state of health using the same impedance measurement infrastructure. This multi-functionality reduces the need for separate measurement systems for each parameter, thereby limiting the increase in device complexity while achieving high precision across all state estimates
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 precise and efficient estimation of battery states, enhancing safety and performance by optimizing charge/discharge performance, predicting battery lifespan, and preventing thermal runaway.
Implementation Method 1
A method and apparatus are provided for estimating states of a device under test (DUT) using electrochemical impedance spectroscopy (EIS)
Data Source
AI summary
A method comprises obtaining a set of impedance values of a first device under test (DUT) across a range of excitation frequencies for a given set of values of a particular state. The method further comprises determining a relationship between the given set of values of the state and the set of impedance values. The method further comprises storing data representing the relationship in a memory, receiving a voltage signal and a current signal from a second DUT, determining an impedance of the second DUT responsive to receiving the voltage and current signals, and determining a value of the state of the second DUT based on the impedance and the data.