Traction Battery Charge Control for Non-Rested Capacity Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for detecting the capacity of traction batteries in electrified vehicles are inefficient due to the long time required for batteries to reach a rested state, leading to infrequent and inaccurate capacity estimations, especially when vehicles are plugged into chargers soon after use.
Innovation Solution
The method involves actively varying the charging current to estimate the state of charge (SOC) using an extended Kalman filter, allowing for more frequent and accurate capacity detection without waiting for the battery to reach a rested state, by utilizing voltage feedback based on a battery model and persistent excitation during the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods wait for the battery to reach a rested state before detecting capacity, then measurement accuracy is improved, but the detection frequency and productivity deteriorate due to long waiting times
Solution Approach 1:
The system performs preliminary actions by actively varying the charge current during the charging process to excite the battery and enable SOC estimation before the battery reaches a rested state. This allows capacity detection to begin earlier in the charging cycle, reducing the waiting time while maintaining acceptable measurement accuracy through the use of voltage feedback and estimation algorithms.
2Ease of operation
If the vehicle is plugged into a charger soon after use, then convenience and ease of operation are improved, but the accuracy of capacity estimation deteriorates because the battery has not reached a rested state
Solution Approach 1:
The system implements feedback by continuously measuring terminal voltage during charging and using this voltage feedback in an estimation algorithm (such as extended Kalman filter) to estimate SOC and capacity. This closed-loop approach allows the system to compensate for the non-rested state conditions and provide accurate capacity estimation even when charging begins soon after vehicle use.
Solution Approach 2:
The system changes parameters by actively varying the charge current during the charging process rather than maintaining a constant charge current. This parameter variation serves to excite the battery system and generate sufficient voltage responses for accurate SOC estimation, enabling reliable capacity detection without requiring the battery to be in a rested state.
Data Source
AI summary
A method for detecting a capacity of a battery, such as a traction battery of an electrified vehicle, includes varying a charge current provided to the battery and measuring a terminal voltage of the battery as the charge current is being varied. An estimator, that utilizes voltage feedback based on a model of the battery to provide state and parameter estimations of the battery, is driven with the terminal voltage to estimate a state-of-charge (SOC) of the battery. The capacity of the battery may be detected based in part on the SOC.