Battery State of Charge Detection via Diffusion Region Impedance Slope
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Solution Overview
Problem
Existing methods for detecting the state of charge (SOC) of rechargeable batteries, particularly in hybrid and electric vehicles, are not accurate enough, as changes in SOC do not reflect in the impedance in the charge transfer resistance region, limiting the ability to determine recyclability and requiring more precise techniques.
Innovation Solution
A device that measures complex impedances in the diffusion region of a battery, calculates the slope or distance between complex impedances at different frequencies, and uses stored correlations to detect the state of charge, enabling high-accuracy SOC detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If impedance measurement is performed in the charge transfer resistance region, then the measurement method is simple, but the state of charge cannot be detected accurately
Solution Approach 1:
The patent changes the frequency parameter of impedance measurement from the conventional charge transfer resistance region (higher frequencies) to the diffusion region (lower frequencies, specifically 0.01-10 Hz). This parameter change enables SOC detection because impedance in the diffusion region varies with SOC while maintaining measurement simplicity
Solution Approach 2:
The patent introduces a new measurement dimension by focusing on the diffusion region of impedance characteristics rather than the traditional charge transfer resistance region. This dimensional shift in the impedance spectrum allows detection of SOC-dependent changes that are invisible in the conventional measurement region
2Ease of operation
If conventional impedance measurement methods are used, then the measurement process is straightforward, but recyclability determination cannot be made accurately
Solution Approach 1:
The patent modifies the measurement parameters by operating in the diffusion region (0.01-10 Hz) rather than conventional frequencies, enabling reliable SOC detection that correlates with battery recyclability while keeping the measurement process straightforward
Solution Approach 2:
The patent replaces conventional SOC estimation methods (which rely on voltage-current relationships) with impedance-based detection in the diffusion region. This substitution provides more reliable recyclability determination because impedance characteristics in this region directly reflect battery degradation state
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 highly accurate detection of the battery's state of charge, enhancing recycling efficiency and enabling precise control of vehicle-mounted batteries.
Implementation Method 1
measuring complex impedances in a diffusion region of the battery
Implementation Method 2
complex impedances in a diffusion region of the battery
Data Source
AI summary
The present invention pertains to the detection of the state of charge of a battery, whereby the complex impedance in the diffusion region of the battery is used. An arithmetic device such as a computer determines the slope of the complex impedance at least two different frequencies in the diffusion region of a rechargeable battery when a straight-line approximation has been made. The state of charge of the rechargeable battery is detected by using the slope that has been determined, and the relationship between the state of charge and slopes that have been stored in advance in a storage means.