Dynamic Equivalent Circuit Model for Battery Management
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Solution Overview
Problem
Existing battery management systems struggle to accurately predict and manage lithium-ion battery behavior under high discharge rates, particularly in electric vertical takeoff and landing (eVTOL) aircraft, due to complex nonlinear dynamics and rapid changes in state of charge and temperature.
Innovation Solution
An enhanced equivalent circuit model (ECM) is developed, which dynamically adjusts its parameters in real-time based on operational data such as state of charge, temperature, and current. This model includes a series resistance component to account for lithium depletion effects and multiple resistor-capacitor (RC) pairs to capture dynamic voltage responses, ensuring accurate predictions under high discharge conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional equivalent circuit models are used to model battery behavior, then the model structure remains simple, but the prediction accuracy deteriorates under high discharge rates due to inability to capture nonlinear dynamics and lithium depletion effects
Solution Approach 1:
The patent applies the Dynamics principle by making the model parameters dynamic rather than static. The equivalent circuit model incorporates time-varying parameters that adapt to changing operating conditions, allowing the model to accurately capture nonlinear battery dynamics under high discharge rates while maintaining a relatively simple structural framework.
Solution Approach 2:
The patent implements Parameter changes by modifying the electrical parameters of the equivalent circuit model based on the degree of lithium depletion. As lithium depletion progresses, the model dynamically adjusts resistance and capacitance values to reflect the changing electrochemical state, thereby improving prediction accuracy without requiring a completely complex model structure.
2Reliability
If the model parameters are dynamically adjusted in real-time, then the prediction accuracy under varying operating conditions improves, but the computational complexity increases
Solution Approach 1:
The patent applies the Feedback principle by continuously monitoring battery operating conditions and using this information to adjust model parameters in real-time. The degree of lithium depletion is estimated based on terminal voltage and current measurements, and this feedback loop enables the model to maintain high reliability under varying discharge conditions without requiring excessive computational resources.
3Productivity
If simple empirical models are used, then the computational burden remains low, but the ability to accurately predict battery behavior under high discharge rates deteriorates
Solution Approach 1:
The patent applies Mechanics substitution by replacing complex electrochemical mechanisms with an equivalent electrical circuit representation. Instead of directly simulating the complex electrochemical processes that occur during high discharge rates, the patent uses an equivalent circuit model with dynamically adjusted parameters to substitute for these mechanical/electrochemical processes, maintaining computational efficiency while improving prediction accuracy.
Data Source
AI summary
Examples relate to a battery management system with an enhanced equivalent circuit model (ECM) for electric vehicles, including electric vertical takeoff and landing (eVTOL) aircraft. The system includes a memory to store an equivalent circuit model (ECM) configured to dynamically adjust a series resistance component in real-time based on operational data from a lithium-ion battery. This adjustment models lithium depletion effects under high discharge conditions. At least one processor is configured to continuously refine parameters of the ECM by analyzing discrepancies between predicted and actual battery performance, where the adjustments are based on real-time changes in state of charge, temperature, and current.