Battery ECM Estimation Using EIS During Rest and Constant Current
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Solution Overview
Problem
Existing battery management systems struggle to accurately estimate the state of secondary batteries, particularly during rest periods and constant current operation sections, due to the lack of current changes, which hinders precise estimation of equivalent circuit model parameters.
Innovation Solution
Implementing an electrochemical impedance spectroscopy (EIS) measurement module to measure impedance, calculate a real intercept and inflection point, and extract equivalent circuit model (ECM) parameters using a processor, enabling accurate estimation throughout the battery's operation, including rest periods and constant current sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage changes according to current changes are used for ECM parameter estimation, then estimation can be performed during dynamic operation, but estimation fails during rest periods and constant current operation sections where no current change occurs
Solution Approach 1:
The patent changes the measurement parameter from current-based voltage changes to frequency-based impedance measurements. By applying AC signals at different frequencies and measuring impedance responses, the system can estimate ECM parameters during rest periods and constant current sections where traditional current-change methods fail, thus improving adaptability across all battery operation sections while maintaining estimation accuracy
Solution Approach 2:
The patent replaces the mechanical/electrical measurement approach (monitoring voltage changes during current transitions) with an electrochemical impedance spectroscopy approach. This substitution enables parameter estimation during static conditions by measuring the battery's frequency response characteristics, allowing ECM parameter extraction throughout the entire battery lifecycle including rest periods
2Measurement precision
If EIS measurement is implemented to enable estimation during rest periods, then estimation accuracy improves across all operation sections, but system complexity increases due to additional measurement hardware and processing
Solution Approach 1:
The patent designs the EIS measurement module to serve multiple functions: it can perform impedance spectroscopy measurements during rest periods, constant current sections, and dynamic operation. The same processor that handles battery management also processes EIS data to extract ECM parameters, reducing overall system complexity while achieving universal applicability across all battery operation sections
Solution Approach 2:
The patent merges the EIS measurement capability with the existing battery management system architecture. The processor integrates both traditional voltage monitoring and EIS-based impedance measurement functions, combining multiple estimation approaches into a unified system that leverages available data from different measurement methods to improve overall estimation accuracy without requiring completely separate systems
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
The solution enhances the accuracy and efficiency of estimating the state of secondary batteries, allowing for precise determination of end-of-life conditions and complementing vulnerabilities in conventional ECM estimation methods.
Implementation Method 1
an electrochemical impedance spectroscopy (EIS) measurement module configured to measure EIS of a secondary battery
Data Source
AI summary
The present disclosure relates to a battery management system and a method for controlling the same. The battery management system according to an embodiment of the present disclosure includes: an electrochemical impedance spectroscopy (EIS) measurement module configured to measure EIS of a secondary battery; a processor configured to receive an EIS measurement result from the EIS measurement module, calculate a real intercept and an inflection point of an impedance value for the secondary battery based on the received EIS measurement result, and extract an equivalent circuit model (ECM) parameter for the secondary battery based on the calculated real intercept and the calculated inflection point.