Battery State Estimation via Voltage and Impedance Segmentation
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Solution Overview
Problem
Current methods for monitoring the state of health and charge of electric vehicle batteries are not sufficiently accurate or convenient, posing safety concerns and limiting user experience.
Innovation Solution
A battery management system that estimates state of health (SoH) using open circuit voltage and electrochemical impedance spectroscopy methods, along with constant current/constant voltage charging techniques, to detect degradation and charge levels, providing precise diagnostics and user interfaces for monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional determination table methods are used to estimate battery state, then the device complexity is reduced, but the measurement precision of battery state of health and charge amount deteriorates
Solution Approach 1:
The patent segments the battery monitoring task into multiple independent measurement components: open circuit voltage measurement, impedance measurement at different frequencies, and charge/discharge capacity measurement. Each component provides specific information about battery state, and their combined analysis achieves high precision without requiring a single complex determination table system.
Solution Approach 2:
The patent changes the measurement parameters by using multiple frequency points for impedance measurement and multiple voltage points for open circuit voltage measurement. This multi-parameter approach enables more accurate battery state estimation compared to traditional single-point determination table methods.
2Measurement precision
If multiple measurement methods are combined to improve battery state estimation accuracy, then the measurement precision improves, but the loss of time increases due to multiple measurements
Solution Approach 1:
The patent performs preliminary measurements of open circuit voltage and impedance characteristics during battery idle periods or charging/discharging waits. These preliminary measurements are stored and used to quickly estimate battery state without requiring full measurement sequences, thus reducing time loss while maintaining precision.
Solution Approach 2:
The patent continuously monitors open circuit voltage and performs periodic impedance measurements during normal battery operation. This continuous data collection allows the system to maintain accurate battery state estimation without interrupting vehicle operation or requiring dedicated measurement time slots.
3Measurement precision
If open circuit voltage and impedance methods are used for battery diagnostics, then the measurement precision of battery state of health improves, but the ease of operation deteriorates due to complex measurement procedures
Solution Approach 1:
The patent implements a self-service measurement system where the battery management controller automatically performs open circuit voltage measurements, impedance measurements at multiple frequencies, and charge/discharge capacity measurements without external intervention. The system autonomously processes the measured data to determine battery state of health and charge amount, eliminating the need for manual operation while maintaining high measurement precision.
Solution Approach 2:
The patent incorporates feedback mechanisms where the measured impedance values and open circuit voltage values are continuously compared against reference data and previous measurements. This feedback loop automatically adjusts measurement parameters and provides real-time battery state assessment, simplifying operation while maintaining diagnostic accuracy.
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
Enhances the safety and convenience of electric vehicle battery monitoring by accurately estimating SoH, extending battery life, and ensuring energy efficiency through precise charge management and diagnostics.
Implementation Method 1
determining a first state-of-charge value from the battery voltage during partial discharge at constant current, determining a second state-of-charge value from the open circuit voltage of the battery
Implementation Method 2
charging the battery with a constant current to a predetermined voltage level
Implementation Method 3
charging the battery at a constant current until a voltage level of the battery reaches a predetermined voltage level, and then charging the battery at a constant voltage until a current level of the battery reaches a predetermined current level
Data Source
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AI summary
A battery state estimation method and apparatus. The apparatus includes a time detector configured to detect a time during which a voltage level of a battery, being partially charged and discharged, changes through a constant current charge. The apparatus also includes a state of health (SoH) information estimator configured to estimate SoH information of the battery with the changed voltage level and the detected time, based on predetermined reference information.