Battery Management System Optimizing Internal Resistance via Dynamic Profiles
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Solution Overview
Problem
Conventional methods for determining internal battery resistance are inadequate in preventing overcharge, as they do not effectively account for changes in resistance due to varying charge currents, even when state of charge and temperature are constant.
Innovation Solution
A battery management system that measures charge current and determines a reference resistance based on voltage-current characteristic profiles, using equations to calculate optimal resistance that adjusts output power and prevents overcharge by considering charge current, internal resistance, and a predetermined upper limit of charge current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional linearization method is used to determine internal resistance, then the determination process is simple, but the accuracy is insufficient to prevent overcharge
Solution Approach 1:
The patent applies dynamics by transitioning from a static linearization method to a dynamic piecewise linearization approach. The voltage-current characteristic is divided into multiple segments with different linearization equations based on the operating point, allowing the system to adapt to changing conditions while maintaining computational efficiency. This resolves the contradiction by making the determination process accurate without being overly complex.
Solution Approach 2:
The patent segments the voltage-current characteristic curve into multiple regions, each with its own linearization parameters. By dividing the characteristic into segments and selecting appropriate linearization equations for each segment, the system achieves higher accuracy in internal resistance determination while keeping each segment's calculation relatively simple, thus resolving the contradiction between accuracy and complexity.
2Reliability
If fixed internal resistance value is used, then the control is simple, but the battery cannot be protected under varying charge current conditions
Solution Approach 1:
The patent implements dynamic adjustment of internal resistance based on the operating point and charge current conditions. Rather than using a fixed resistance value, the system continuously determines the appropriate resistance from the segmented voltage-current characteristic, ensuring reliable overcharge protection while adapting to varying conditions. This dynamic approach resolves the contradiction between protection reliability and control complexity.
Solution Approach 2:
The patent changes the internal resistance parameter dynamically based on operating conditions. By selecting different linearization parameters from the segmented characteristic curve according to the current operating point, the system achieves reliable protection across varying charge current conditions while maintaining a relatively simple control structure through parameter selection rather than complex calculations.
Data Source
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AI summary
A battery management system for optimizing the internal resistance of a battery includes a current measuring unit that measures a charge current of the battery, a memory that stores a plurality of voltage-current characteristic profiles, and a control unit that determines a reference profile from the plurality of voltage-current characteristic profiles based on a state of charge and temperature of the battery. The reference profile includes a start point, an end point, and a plurality of intermediate points disposed between the start point and the end point. The control unit determines an internal resistance of the battery, sets one of the plurality of intermediate points as a reference point, determines a reference resistance based on the reference point and the end point, and determines an optimal resistance based on the charge current, the internal resistance, the reference resistance and a predetermined upper limit of charge current.