EV Battery SOH Estimation Using Segmented Charge-Time Analysis
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Solution Overview
Problem
Electric vehicles face challenges in accurately estimating the state of health (SOH) of batteries due to variations in cell characteristics and driving habits, making it difficult to determine the current SOH.
Innovation Solution
A method that determines charge times in different voltage periods corresponding to various charge current values, updates charge times based on environmental conditions, and calculates the state of health by averaging and removing abnormal points from the charge times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If battery characteristic test is performed every time to estimate SOH, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent pre-divides the battery charging voltage range into multiple voltage periods before actual charging occurs. By having these periods predetermined and establishing reference charge times in advance, the system avoids the need for complex real-time analysis, thus reducing inspection time while maintaining SOH estimation accuracy through the use of pre-prepared charging stage benchmarks.
2Measurement precision
If battery SOH estimation accounts for cell characteristics and driving habits, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the battery charging process into multiple voltage periods with different charge current characteristics. By dividing the charging voltage range into distinct segments (e.g., first voltage period, second voltage period, third voltage period), the system can analyze SOH based on charge times in each segment without needing to account for all possible cell characteristics and driving habits simultaneously, thus reducing control system complexity while maintaining estimation accuracy.
3Reliability
If charge times are updated based on environmental conditions, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent updates charge times by changing the parameter of charging current based on environmental conditions such as temperature. The battery controller adjusts the charge current magnitude according to detected temperature, and correspondingly updates the reference charge times for each voltage period. This approach improves SOH estimation reliability under varying environmental conditions while avoiding the need for complex control mechanisms by simply adjusting current parameters.
Data Source
AI summary
An electrified vehicle and a method of inspecting the electrified vehicle, includes determining a charge time in each of voltage period corresponding to different charge current values, respectively, and determining a state of health of a battery based on charge times in at least one or more periods of the determined charge times in the periods.