Battery Internal Resistance Estimation by CC Current Interpolation
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Solution Overview
Problem
Existing methods fail to accurately estimate battery internal resistance in arbitrary charging environments using constant current (CC) charging, which is crucial for determining the state of charge (SOC) and state of health (SOH) of batteries in high-powered vehicles.
Innovation Solution
A method and apparatus that utilize stored battery charging information from multiple constant current charges to estimate internal resistance by interpolating between two closest charging information items, one with a current larger and one smaller than the target current, using a control unit to determine resistance based on initial SOC and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If battery charging information is stored for multiple constant currents to enable accurate estimation in arbitrary charging environments, then measurement precision of internal resistance is improved, but device complexity increases due to larger storage requirements and more complex interpolation logic
Solution Approach 1:
Battery charging information including voltage, current, temperature, and SOC data is pre-stored in the storage unit for multiple constant current values. This preliminary data collection enables the control unit to perform accurate internal resistance estimation by retrieving and interpolating between stored data points, eliminating the need for real-time complex measurements while maintaining high precision across various charging conditions
Solution Approach 2:
The system changes the constant current parameter to multiple discrete values and stores corresponding charging information for each. By varying the current parameter and pre-recording the battery's voltage, temperature, and SOC responses, the system creates a comprehensive data set that enables accurate internal resistance calculation through interpolation, resolving the contradiction between precision and complexity
2Adaptability or versatility
If interpolation between two closest charging information items is used to estimate internal resistance for target constant current, then adaptability to arbitrary charging environments is improved, but calculation complexity increases
Solution Approach 1:
The control unit changes the target constant current parameter and retrieves stored charging information for the two closest current values. By systematically varying the target current and performing linear interpolation between the two nearest stored data points, the system achieves high adaptability to any charging condition while maintaining relatively simple calculation logic that is easily implementable in the control unit
Data Source
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AI summary
The present invention relates to an apparatus and method of estimating the battery internal resistance, and a battery internal resistance estimating apparatus according to an exemplary embodiment of the present invention includes a storage unit that stores a plurality of battery charging information items which is obtained during charging of a battery with a plurality of constant currents, and a control unit that reads multiple battery charging information items having an initial SOC identical to a target initial SOC from among the plurality of battery charging information items, determines whether there is any battery charging information item corresponding to a constant current identical to a target constant current among the multiple read battery charging information items, and estimates the internal resistance of the battery according to the target initial SOC and the charging with the target constant current, using two battery charging information items corresponding to two constant currents close to the target constant current, when it is determined that there is no battery charging information item according to a constant current identical to the target constant current.