Battery State Estimation via Relaxation Voltage Mapping
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Solution Overview
Problem
Existing methods for estimating the state of charge and state of aging of electrochemical battery systems in vehicles require significant computing resources, making them unsuitable for on-board applications in vehicles with limited computing means and energy constraints.
Innovation Solution
A method that detects a relaxation phase in the battery, measures the open-circuit voltage, and uses a predetermined map to estimate the relative state of charge and aging parameters, allowing for precise estimation of the battery's state without complex calculations, utilizing a control unit with a memory that stores values of state parameters as a function of open-circuit voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex parametric optimization models with equivalent electrical circuits are used to determine state of charge and state of aging, then measurement precision is improved, but device complexity and computing resource requirements increase significantly
Solution Approach 1:
The patent segments the state estimation problem into two distinct phases: a relaxation phase where the battery is at rest and open circuit voltage is measured, and an operational phase where the battery is charging or discharging. This segmentation allows the use of simple voltage measurements during relaxation to determine state of charge and state of aging, avoiding the need for complex continuous computation during operational phases.
Solution Approach 2:
The patent performs state estimation during a relaxation phase that occurs before the battery enters full operational use. By utilizing this preliminary period when the battery is at rest, the system can perform measurements and calculations without interfering with the primary function of power delivery, and with minimal computational resources.
2Productivity
If real-time estimation of state of charge and state of aging is performed using complex models, then productivity is improved, but use of energy increases due to computational requirements
Solution Approach 1:
The patent segments the estimation process to occur only during relaxation phases, separating it from continuous operational monitoring. This allows real-time capability to be maintained while energy consumption is minimized by performing computations only when the battery is at rest, not continuously during high-power operation.
Solution Approach 2:
The patent uses simple, low-cost measurement approaches (voltage measurement during relaxation) instead of expensive, energy-intensive complex modeling. The relaxation phase itself is a temporary, short-lived state that is exploited for estimation purposes, after which the battery returns to normal operation with updated state information.
3Measurement precision
If complex parametric optimization is used for state estimation, then measurement precision is improved, but ease of operation deteriorates due to deployment constraints in embedded systems
Solution Approach 1:
The patent segments the estimation approach to use simple relaxation-based measurements during battery rest periods, making the system easy to deploy in embedded automotive applications with limited computing power. The complex state of aging estimation is performed only during these segmented relaxation phases rather than requiring continuous complex computation.
Solution Approach 2:
The patent replaces complex computational mechanics (parametric optimization with particle swarm optimization) with a simpler electrochemical-based measurement approach during relaxation. This substitution makes the system more suitable for embedded deployment while maintaining measurement precision for state of aging estimation.
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 real-time estimation of battery state with reduced computational requirements, improving the precision of vehicle powertrain control and enabling diagnostic checks of sensors, thus optimizing electrical consumption and management of the battery system.
Implementation Method 1
a relaxation phase, the continuous measurement of a voltage signal across the terminals of the battery in relaxation, the estimation of the open-circuit voltage from the voltage signal measured in relaxation
Data Source
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AI summary
The present invention concerns the management of battery systems in order to determine the state of ageing parameter and state of charge parameter. The invention aims to reduce the calculation resources necessary for real-time estimation of such parameters. The invention concerns a method including a step (208) of estimating the state of ageing parameter and/or the current state of charge parameter by reading a predetermined mapping providing predetermined values of a state parameter dependent on a relative state of charge parameter (SOCen) and the state of ageing parameter as a function of predetermined values of the open circuit voltage (OCV).