Battery String Charging with Two-Stage Module Selection
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Solution Overview
Problem
Existing methods struggle to effectively select and charge battery modules in a battery string when all modules have substantially the same state of charge, particularly when the charging voltage is insufficient to charge all modules simultaneously.
Innovation Solution
A method involving a switching arrangement to control connectivity of battery modules based on first and second state of charge estimation methods, including steps to establish state of charge, associate modules with unique identifications, measure current and voltage, and control connectivity to balance charge, ensuring all modules reach a predetermined voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single state of charge estimation method is used to select battery modules for charging, then the selection process is simple, but reliable state of charge estimation cannot be established when all battery modules have substantially the same state of charge
Solution Approach 1:
The charging control system is segmented into two distinct phases: a first state of charge estimation method (e.g., coulomb counting) for initial module selection and balancing, and a second state of charge estimation method (voltage measurement) for precise charging completion detection. This segmentation allows each method to be optimized for its specific function, resolving the contradiction between measurement precision and system complexity.
Solution Approach 2:
The first state of charge estimation method is applied preliminarily to balance the state of charge among all battery modules before the second method is used. This preliminary action ensures that when the second method (voltage measurement) is applied, at least some modules will have distinguishable voltage levels, enabling reliable state of charge estimation and charging completion detection.
2Reliability
If charging voltage is insufficient to charge all battery modules simultaneously, then charging time is extended, but productivity is reduced
Solution Approach 1:
The first state of charge estimation method performs preliminary balancing of all battery modules before the second method begins. This ensures that when charging proceeds with limited voltage capacity, the system can reliably detect charging completion for each module individually based on voltage thresholds, preventing undercharging while maximizing the use of available charging power.
Solution Approach 2:
The two-state estimation methods operate in continuous sequence: the first method continuously monitors and balances modules, while the second method continuously detects charging completion. This continuous operation ensures that charging productivity is maximized by immediately transitioning modules from charging to discharged status as soon as they reach full charge, preventing idle charging time.
3Productivity
If battery modules are selected for charging without proper state of charge differentiation, then all modules can be charged simultaneously, but state of charge balance is lost
Solution Approach 1:
The charging process is segmented into module selection based on first state of charge estimation and charging completion detection based on second state of charge estimation. This segmentation enables the system to maintain state of charge balance by using the first method to identify modules needing charge while using the second method to precisely determine when each module reaches full charge, preventing overcharging and maintaining uniformity.
Solution Approach 2:
The system implements feedback control by continuously monitoring battery module voltages during charging and using the second state of charge estimation method to detect when modules reach predetermined voltage thresholds. This feedback mechanism allows the controller to dynamically adjust charging connectivity, maintaining state of charge balance across all modules while maximizing charging efficiency.
Data Source
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AI summary
The present invention relates to 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 include the following steps: establish state of charge of said battery modules and control connectivity of the battery modules to the battery string according to said established state of charge so as to balance state of charge among said battery modules. The second method include 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.