Battery Internal Resistance Estimation for Aging-Aware Power Prediction
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Solution Overview
Problem
Electrical energy storage units in vehicles experience aging effects, leading to outdated internal resistance values, which can result in overestimation of retrievable power and delayed replacement, as they may be indicated as functional despite reduced performance.
Innovation Solution
A method to determine an up-to-date resistance parameter of electrical energy storage units by calculating a current and voltage variable using a mathematical model, with an adaptation value to account for temperature dependence, and filtering to reduce noise interference, allowing for improved operation and extended lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance parameter values are recorded at production or before first use, then initial accuracy is achieved, but the values become outdated over time due to aging effects
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously determines updated resistance parameter values based on measured current and voltage variables from the energy storage unit. The system compares measured voltage with model-calculated voltage and uses the difference to adapt the resistance parameter, ensuring continuous updates without manual intervention throughout the unit's operational life.
Solution Approach 2:
The energy storage unit performs self-diagnosis through the control unit that automatically monitors its own electrical parameters (current and voltage), calculates resistance values using mathematical models, and updates the resistance parameter without external intervention. This self-service approach maintains accurate resistance values throughout the unit's lifecycle.
2Device complexity
If outdated resistance parameter values are used, then system complexity is reduced, but power prediction accuracy deteriorates leading to overestimation of retrievable power
Solution Approach 1:
The patent replaces complex physical measurement systems with a mathematical model approach. Instead of using additional sensors or complex measurement equipment to directly measure resistance, the system uses electrical variables (current and voltage) combined with a mathematical model to calculate and determine the resistance parameter, simplifying the physical system while maintaining accuracy.
Solution Approach 2:
The system dynamically changes the resistance parameter based on operating conditions by continuously updating it using measured electrical variables and mathematical models. This allows the resistance parameter to adapt to aging effects and temperature changes without requiring complex hardware modifications.
3Reliability
If continuous monitoring of resistance parameter is implemented, then operational safety is improved, but energy consumption increases
Solution Approach 1:
The patent implements continuous monitoring of electrical parameters (current and voltage) that are already being measured for normal operation of the energy storage unit. By utilizing these existing measurements for resistance parameter calculation, the system achieves continuous safety monitoring without requiring additional energy-consuming sensors or measurement systems.
Solution Approach 2:
The control unit performs multiple functions: it manages the normal operation of the energy storage unit, measures electrical parameters for performance monitoring, and simultaneously calculates resistance parameters for safety assessment. This multi-functionality allows continuous safety monitoring using the same hardware and energy resources already allocated for operational management.
Data Source
AI summary
A method for determining a resistance parameter value of an electrical energy storage unit is disclosed, comprising the following steps:a) determining a current variable representing an electric current flowing into or out of the electrical energy storage unit;b) determining a first voltage variable, which represents an electrical voltage prevailing between two pole terminals of the electrical energy storage unit;c) determining a second voltage variable, which represents an electrical voltage and results from a mathematical model of the electrical energy storage unit, wherein the current variable determined in step a) is applied to the mathematical model and the latter comprises a resistance parameter which represents an internal resistance of the electrical energy storage unit and to which a first value is allocated;d) generating an adaptation value for the resistance parameter, wherein the adaptation value is dependent on a difference variable between the first voltage variable and the second voltage variable; ande) determining a second value of the resistance parameter as a sum of the first value of the resistance parameter and the adaptation value.