Battery Internal Resistance Component Measurement From OCV Relaxation
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Solution Overview
Problem
Conventional methods struggle to individually measure the resistance components constituting the internal resistance of a battery in a simple manner.
Innovation Solution
A method involving a conduction step, measurement step, and calculation step, where the open circuit voltage is measured at the end of charging or discharging, and resistance components are calculated based on the slope of a graph plotting the voltage change against the square root of elapsed time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used, then the internal resistance of the battery can be measured, but it is difficult to individually measure resistance components in a simple manner
Solution Approach 1:
The patent segments the internal resistance measurement into distinct resistance components (R1, R2, R3) corresponding to different time constants. By measuring voltage changes at multiple specific time points after current interruption and applying segmented calculation formulas, each resistance component can be individually determined. This segmentation approach transforms a complex measurement problem into manageable separate measurements, enabling individual resistance component measurement without excessive complexity.
2Speed
If conventional measurement methods are used, then the internal resistance can be measured, but the response speed is slow
Solution Approach 1:
The patent applies preliminary action by pre-determining the specific time points for voltage measurement based on the battery's time constants before actual measurement occurs. The measurement method is designed to capture voltage changes at optimally selected time points (immediately after current interruption and at subsequent predetermined intervals), ensuring that each measurement captures the appropriate resistance component. This preliminary planning of measurement timing enables fast response while maintaining precision for individual resistance component measurement.
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 individual measurement of resistance components, allowing for detailed evaluation of battery performance and state, particularly deterioration, with a fast response speed.
Implementation Method 1
a conduction step of charging or discharging the battery
Implementation Method 2
a measurement step of measuring an open circuit voltage of the battery
Implementation Method 3
a calculation step of individually calculating at least one resistance component included in the internal resistance, based on a voltage change of the open circuit voltage measured in the measurement step and a current value of current flowing through the battery
Data Source
AI summary
The disclosed method is a method for measuring the internal resistance of a battery. The measurement method includes a conduction step of charging or discharging the battery, a measurement step of measuring an open circuit voltage of the battery at the end time of the charging or discharging and thereafter, and a calculation step of individually calculating at least one resistance component included in the internal resistance, based on a voltage change of the open circuit voltage measured in the measurement step and a current value of current flowing through the battery for the charging or discharging at the end time. In the calculation step, the at least one resistance component is calculated based on a slope of a line obtained by plotting the voltage change in a graph in which a horizontal axis indicates a square root of an elapsed time from the end time and a vertical axis indicates the open circuit voltage.