Battery Power Limit Estimation Using Fleet-Based Current Profiles
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Solution Overview
Problem
Current methods for determining power and current limits for propulsion batteries in vehicles often lead to conservative or overestimated values due to the assumption of constant power output, which does not reflect real-world usage patterns.
Innovation Solution
A method that utilizes vehicle fleet data to categorize power usage profiles and calculate a time-dependent averaged current profile, which is applied to electrical energy storage cells to realistically age them and determine accurate power or current limits based on expected driving behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat C-rate aging process with constant power output is used to determine battery limits, then the calculation process is simple, but the resulting power limits are conservative or overestimated and do not reflect real-world usage
Solution Approach 1:
The patent transitions from a static constant power output assumption to a dynamic time-dependent current profile that varies over time. The current profile I(t) is derived from real-world driving data and applied during battery aging tests to simulate actual usage patterns, thereby improving the accuracy of power limit estimations while maintaining a manageable test procedure
Solution Approach 2:
The patent creates a simplified copy of real-world driving conditions by deriving a representative current profile from extensive field data. This profile captures the essential characteristics of actual battery usage without requiring complex real-time data collection during testing, thus achieving accurate power limit estimation with a practical test methodology
2Measurement precision
If real-world variable power output is used in aging tests, then the power limit estimation is more accurate, but the test procedure becomes more complex
Solution Approach 1:
The patent performs preliminary analysis of real-world driving data to derive a representative time-dependent current profile before conducting the aging test. This pre-processing step consolidates complex variable power patterns into a single reusable profile that can be applied during the aging test, simplifying the actual test execution while maintaining accuracy
Solution Approach 2:
The patent transforms the complex variable power output function into a parameterized current profile I(t) that captures essential usage characteristics. By changing the representation from raw variable power data to a standardized current profile with defined parameters, the system achieves accurate power limit estimation without requiring complex test equipment or procedures
Data Source
AI summary
A method for estimating a power or current limit for an electrical energy storage system is provided. The method includes obtaining vehicle fleet data indicating power usage of a fleet of vehicles in a geographical area; categorizing the vehicle fleet data into a set of power usage profiles depending on an expected amount of power usage determined from the vehicle fleet data; calculating a time dependent averaged current profile from a distribution of the power usage profiles; and applying the time dependent averaged current profile to an electrical energy storage cell to age the electrical energy storage cell to a predetermined state of health, and determining the power or current limit for the electrical energy storage cell.