Battery Charge Prediction Model Using State Estimation
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Solution Overview
Problem
Existing methods for determining the charge able to be drawn from energy stores, such as batteries, are imprecise and fail to account for factors like active mass loss and ice formation, making it difficult to predict the charge available before reaching a specified cutoff criterion.
Innovation Solution
A device and method using a mathematical energy store model that incorporates discharge current and temperature characteristics, along with a state and parameter estimator, to calculate the charge able to be drawn, taking into account physical effects like internal resistance, acid diffusion, and charge transfer polarization, and adjusting for cutoff criteria such as minimum electrolyte voltage, terminal voltage, and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the charge able to be drawn is determined using empirically ascertained characteristics maps and the Peukert formula, then it is possible to ascertain the charge able to be drawn up to a cutoff characterized by complete discharge, but it is not possible to determine the charge able to be drawn before undershooting a specified minimum terminal voltage or minimum capacity
Solution Approach 1:
The patent changes the parameters used in charge prediction from simple Peukert formula parameters to a comprehensive set including temperature-dependent parameters, active mass loss parameters, and ice formation parameters. This allows the system to adapt to different cutoff criteria (minimum terminal voltage, minimum capacity, or complete discharge) by adjusting which parameters are applied in the mathematical model.
Solution Approach 2:
The patent implements dynamic adjustment of the mathematical energy store model parameters based on current operating conditions. The state variable and parameter estimator continuously updates parameters such as internal resistance, acid diffusion resistance, and charge transfer polarization based on real-time measurements, enabling accurate prediction across varying cutoff criteria and operating conditions.
2Ease of manufacture
If the charge able to be drawn is determined using the Peukert formula, then a calculation method is provided, but the determination is relatively imprecise because different effects influencing the state of the cutoff such as active mass loss at the electrodes due to aging or ice formation at low temperatures are not taken into account
Solution Approach 1:
The patent segments the charge prediction calculation into multiple independent components: a mathematical energy store model with separate parameters for internal resistance, acid diffusion resistance, and charge transfer polarization. Each parameter can be independently adjusted based on specific effects (aging, temperature, ice formation), allowing the system to maintain calculation simplicity while incorporating multiple physical effects through modular parameter adjustments.
3Measurement precision
If a mathematical energy store model with multiple mathematical models representing different physical effects is used, then precise determination of charge able to be drawn before meeting specified cutoff criteria is achieved, but the device complexity increases
Solution Approach 1:
The patent creates a universal mathematical energy store model that can handle multiple cutoff criteria (minimum terminal voltage, minimum capacity, complete discharge) and multiple operating conditions (different temperatures, aging states, ice formation) through a single integrated framework. The state variable and parameter estimator serves multiple functions by simultaneously estimating state variables and parameters, reducing the need for separate calculation systems for different scenarios.
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
Enables precise determination of the charge able to be drawn before reaching specified cutoff criteria, improving accuracy and preventing over-discharge by considering various physical effects, thereby enhancing energy management in applications like automotive systems.
Implementation Method 1
The energy store model includes in the case of a battery at least one model for the internal resistance Ri of the battery
Implementation Method 2
The energy store model includes in the case of a battery at least one model for an acid diffusion resistance Rk
Implementation Method 3
The energy store model includes in the case of a battery at least one model for a charge transfer polarization UD
Data Source
AI summary
A device for ascertaining the charge able to be drawn from an energy store, in particular a battery, up to a specified cutoff, is provided. A particularly precise charge prediction may be achieved if a mathematical energy store model is used, which mathematically represents the electrical properties of the energy store and with the aid of which a charge predictor calculates the charge able to be drawn in the case of a specified discharge current. The charge predictor is connected with an estimator for a state variable and parameter, which estimator ascertains state variables and/or parameters for the mathematical energy store model from current operating performance quantities of the energy store.