Diffusion Circuit Model for Battery State of Charge
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Solution Overview
Problem
Existing battery modeling methods for hybrid electric vehicles do not account for diffusion in the electrochemical system, which is crucial for accurate state of charge determination and energy management.
Innovation Solution
A method and apparatus that incorporate a diffusion circuit model to estimate and calculate diffusion voltage, using a processor to determine battery condition parameters, and an energy management controller to integrate this information for improved state of charge estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prior equivalent circuit models are used to determine battery state of charge, then the method provides an effective model for SOC determination, but the model fails to account for diffusion in the battery system resulting in reduced accuracy
Solution Approach 1:
The battery model is segmented into multiple components: an equivalent circuit model for electrical characteristics and a diffusion model for mass transport. The total voltage is expressed as the sum of ohmic drop, capacitive voltage, and diffusion voltage, allowing each physical process to be modeled separately and combined for comprehensive SOC determination.
Solution Approach 2:
The patent combines two different modeling approaches (equivalent circuit model and diffusion model) into a composite battery model. The equivalent circuit captures electrical behavior while the diffusion model captures mass transport, creating a more complete and accurate representation of battery physics.
2Measurement precision
If a diffusion circuit model is added to account for diffusion processes, then the model accuracy improves, but the device complexity increases
Solution Approach 1:
A diffusion voltage term acts as an intermediary that bridges the equivalent circuit model and the diffusion model. This diffusion voltage represents the concentration gradient effects and allows the two different physical processes to be coupled in a mathematically tractable way without requiring a completely complex model.
Solution Approach 2:
The patent introduces a time-varying diffusion voltage parameter that changes based on battery operating conditions. By modeling diffusion voltage as a dynamic parameter rather than a static value, the model adapts to changing conditions while maintaining computational efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the accuracy of state of charge determination by accounting for diffusion processes, enabling better energy management and decision-making in hybrid electric vehicle systems.
Implementation Method 1
calculating a new diffusion voltage using an equation based on a diffusion circuit model
Data Source
AI summary
A method for determining a diffusion voltage in an electrochemical cell (e.g., a battery used in connection with an automotive vehicle) includes estimating a previous diffusion voltage, calculating a new diffusion voltage using an equation based on a diffusion circuit model and the previous diffusion voltage, and setting the previous diffusion voltage equal to the new diffusion voltage. The step of calculating the new diffusion voltage may then be repeated.