Battery String Module Charging with Dual SoC Estimation
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Solution Overview
Problem
Existing methods fail to effectively select and charge battery modules in a battery string when all modules have substantially the same state of charge, especially when the charging voltage is insufficient to charge all modules simultaneously.
Innovation Solution
A method involving a switching arrangement for each battery module, utilizing a first state of charge estimation based on Coulomb counting and a second estimation method using battery cell voltage measurements to ensure all modules reach a predetermined voltage, with a dynamic list sorting and unique module identification for balanced charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single state of charge estimation method is used, then the system is simple to operate, but reliable state of charge estimation cannot be established for all battery modules
Solution Approach 1:
The state of charge estimation process is segmented into two distinct methods: a first estimation method using coulomb counting for initial state of charge determination, and a second estimation method using voltage measurements for final state of charge verification. This segmentation allows each method to be optimized for its specific function, ensuring reliable state of charge estimation across all battery modules while maintaining operational simplicity through automated sequential execution.
2Productivity
If all battery modules are charged simultaneously, then charging efficiency is maximized, but the charging voltage available is insufficient to charge all modules simultaneously
Solution Approach 1:
The system dynamically adjusts the charging sequence based on real-time state of charge measurements. Battery modules are sorted according to their state of charge levels, and the charging process dynamically transitions between modules as they reach target voltage levels. This dynamic approach maximizes charging efficiency within the constraints of available charging voltage by continuously optimizing which modules receive charging current.
Solution Approach 2:
The charging process employs periodic action by cycling through different battery modules in sequence. When one module reaches its target voltage, the system periodically switches to the next module in the sorted list. This periodic charging pattern ensures that all modules eventually receive adequate charging while working within the limitations of the available charging voltage capacity.
3Productivity
If battery modules are selected based on state of charge alone, then charging is efficient, but modules with substantially the same state of charge cannot be differentiated for charging selection
Solution Approach 1:
When battery modules have substantially the same state of charge and cannot be differentiated by state of charge alone, the system introduces an intermediary selection criterion: module identification number. This intermediary parameter serves as a tiebreaker to enable definitive selection of which modules to charge first, maintaining charging efficiency while solving the differentiation problem for modules with identical state of charge measurements.
Data Source
AI summary
A method of selecting and charging battery modules connected in a battery string based on a first method and subsequently based on a second method. The first method includes the following steps: establish a state of charge of the battery modules and control connectivity of the battery modules to the battery string according to the established state of charge, to balance the state of charge among the battery modules. The second method includes the following steps: associate the battery modules with a unique battery module identification, establish a battery module current, establish battery cell voltage of battery cells comprised by the battery modules, control connectivity of the battery modules to the battery string according to the battery module identifications, and charge the battery module connected to the battery string for a determined period of time.