EIS Excitation Circuit Using Cell-to-Cell Energy Transfer
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Solution Overview
Problem
Existing battery monitoring systems face challenges in accurately and efficiently estimating the state of charge (SoC) and state of health (SoH) of electrochemical devices, particularly due to energy loss and heat generation when using resistors for AC excitation in electrochemical impedance spectroscopy (EIS) measurements.
Innovation Solution
An electrochemical impedance spectroscopy (EIS) excitation system that transfers energy between electrochemical devices using energy transfer circuitry and a controller to generate an EIS excitation signal, employing a carrier frequency for efficient energy transfer and minimizing energy loss, allowing for accurate SoC and SoH estimation without separate excitation devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a resistor is used to generate AC excitation current for EIS measurements, then the excitation signal can be generated, but energy is lost and heat is generated in the resistor
Solution Approach 1:
The patent applies the self-service principle by using the battery cells themselves to generate the AC excitation current through controlled charge-discharge cycles, rather than using an external resistor. The battery cells serve dual purposes: as the object being tested and as the excitation signal generator, eliminating energy loss and heat generation in external resistors.
Solution Approach 2:
The patent introduces a controller as an intermediary that coordinates energy transfer between battery cells to generate the excitation signal. The controller manages the charge-discharge cycles and energy distribution, enabling the system to produce AC excitation without dissipative components like resistors.
2Loss of energy
If energy is transferred between electrochemical devices to generate AC excitation, then energy loss and heat generation are reduced, but the system complexity increases
Solution Approach 1:
The patent applies universality by making the battery cells multi-functional: they serve as both the electrochemical devices under test and as the energy storage elements for generating excitation signals. The same cells that are being characterized also provide the energy for excitation, eliminating the need for separate excitation hardware.
Solution Approach 2:
The patent merges the excitation signal generation function with the battery testing function. By combining these two functions into a single integrated system where battery cells interact with each other, the patent eliminates separate excitation devices and reduces overall system complexity despite the sophisticated control algorithms required.
3Measurement precision
If multiple frequencies are used for EIS measurements, then more comprehensive SoC and SoH information is obtained, but the measurement time increases
Solution Approach 1:
The patent applies periodic action by using a carrier signal with a specific frequency (e.g., 1 kHz) to modulate the excitation. This periodic carrier signal enables the system to efficiently extract impedance information across multiple frequencies through frequency domain analysis, reducing the time required compared to sequential measurements at each frequency.
Solution Approach 2:
The patent performs preliminary action by pre-selecting optimal carrier frequencies and measurement parameters before conducting the EIS analysis. The system is configured with predetermined frequency ranges and measurement protocols that optimize the balance between measurement comprehensiveness and time efficiency, allowing rapid acquisition of SoC and SoH data.
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 estimation of SoC and SoH with reduced energy loss and heat generation, improving the reliability and efficiency of battery monitoring systems by using discrete pulses at a carrier frequency to generate an EIS excitation signal across electrochemical devices.
Implementation Method 1
energy transfer circuitry, which may be configured to transfer energy from a first electrochemical device to a second electrochemical device
Implementation Method 2
electrochemical device may include an arrangement of one or more battery cells, one or more fuel cells, one or more electrolysis cells, one or more other electrochemical cells
Data Source
AI summary
An electrochemical impedance spectroscopy (EIS) excitation system may include energy transfer circuitry, which may be configured to transfer energy from a first electrochemical device to a second electrochemical device. The EIS excitation system may also include a controller, which may be configured to control the energy transfer circuitry to generate an EIS excitation signal for the first electrochemical device. The controller may be configured to control the energy transfer circuitry to transfer energy in a first direction between the first electrochemical device and the second electrochemical device for a first portion of an EIS excitation signal cycle.