Traction Battery Controller for Low-Temperature Power Capability Mapping
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Solution Overview
Problem
Existing methods for estimating the power capability of traction batteries in low temperature environments fail to account for the current-dependent variance of battery model parameters, leading to inaccurate power capability measurements due to differences between learned and actual parameter values.
Innovation Solution
The battery management system adjusts for current-dependent variance of battery model parameters by mapping learned parameter values from a different battery current to the current used in power capability calculation, using methods such as extended Kalman filtering and structural functions to ensure accurate power capability estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If battery model parameters are learned using extended Kalman filtering with the current battery current, then the parameter learning is simple and efficient, but the learned parameter values differ from actual values when battery current varies, leading to inaccurate power capability estimation
Solution Approach 1:
The patent introduces a mapping relationship as an intermediary between the learned parameter values (from EKF at one current level) and the actual parameter values (at a different current level). This mapping function translates parameters learned at current I1 to the equivalent parameters at current I2, allowing the system to maintain simple EKF-based learning while achieving accurate power capability estimation at varying current levels.
2Duration of action of stationary object
If the battery current used for parameter learning is kept different from the power capability calculation current to maintain system operation, then the battery can operate continuously, but the parameter values become inaccurate for power capability detection
Solution Approach 1:
The patent applies parameter changes by introducing a mapping relationship that transforms parameter values based on battery current conditions. When battery current changes from the learning current to the calculation current, the mapping function adjusts the parameter values accordingly, maintaining both continuous operation and accurate power capability detection through dynamic parameter adaptation.
Data Source
AI summary
A system, such as an electrified vehicle, includes a battery, such as a traction battery. The system further includes a controller configured to charge and/or discharge the battery based on a power capability of the battery defined by a value of a parameter of a model of the battery mapped from a value of the parameter that is learned with a battery current of the battery different from a battery current used in calculating the power capability.