Battery Capacity Estimation Using Coulomb Flow and Voltage
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Solution Overview
Problem
Existing methods for determining the state of health (SOH) of rechargeable batteries in vehicles are time-consuming and not suitable for on-board applications, particularly in hybrid electric vehicles that require accurate and robust capacity estimation for reliable operation.
Innovation Solution
An on-board system estimates battery capacity using voltage and current signals over time intervals to determine the state of charge and net coulomb flow, enabling monitoring of battery health and enhancing charging control and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full charging and discharging process is used to determine battery capacity, then measurement precision is improved, but time consumption increases and it becomes unsuitable for on-board applications
Solution Approach 1:
The patent applies partial action by using only a portion of the full charging-discharging cycle. Instead of completing entire charge and discharge cycles, the method uses partial charge/discharge segments combined with voltage-based SOC estimation to calculate capacity. This reduces the time required while maintaining adequate measurement precision for on-board applications.
Solution Approach 2:
The patent replaces the mechanical/electrical full charge-discharge process with an electrical measurement and calculation system. By using voltage measurements, current signals, and computational algorithms to estimate SOC and calculate capacity, the system substitutes the time-consuming physical charge-discharge process with faster electrical measurements and mathematical computations.
2Speed
If voltage-based state of charge estimation is used, then real-time monitoring capability is improved, but measurement precision may be affected by voltage signal accuracy
Solution Approach 1:
The patent implements feedback by continuously monitoring voltage and current signals and using them to update the state of charge estimation in real-time. The system processes measured voltage and current data through computational algorithms that adjust SOC estimates based on actual battery behavior, improving precision while maintaining real-time capability.
Solution Approach 2:
The patent applies multi-functionality by using the voltage-based SOC estimation system to perform multiple functions: real-time SOC monitoring, capacity estimation, and state of health assessment. This integrated approach allows the same measurement system to provide comprehensive battery management information without requiring separate dedicated systems for each function.
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
This approach allows for accurate and efficient estimation of battery capacity and state of health in real-time, improving the reliability and safety of hybrid electric vehicle systems by providing enhanced power management and charging control.
Implementation Method 1
A vehicle's electric power supply system must support a plurality of vehicle functions that operate on electric energy
Implementation Method 2
A net coulomb flow is calculated between the first instant of time and the second instant of time
Data Source
AI summary
An embodiment contemplates a method for estimating a capacity of a battery. A state of charge is determined at a first instant of time and at a second instant of time. A difference in the state of charge is determined between the first instant of time and the second instant of time. A net coulomb flow is calculated between the first instant of time and the second instant of time. The battery capacity is determined as a function of the change in the state of charge and the net coulomb flow.