Battery Cell Balancing via Current Diversion
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Solution Overview
Problem
Conventional cell balancing in battery packs is time-consuming due to the use of low currents near the end of the charge process, which is inefficient and not effective in stabilizing all cells at the target charge level due to inherent capacity differences among battery cells.
Innovation Solution
A method that involves monitoring cell voltage and diverting the charging current around cells that have reached the target charge value, while adjusting the charging current to ensure that cells receiving the target charge value receive substantially zero current, and initiating cell balancing by detecting voltage divergence before cells reach the target charge level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cell balancing is implemented using very low currents near the end of the charge process, then all cells can stabilize at the target charge level, but the charging process becomes rather time consuming
Solution Approach 1:
The system performs preliminary action by detecting voltage divergence among cells before any cell reaches the target charge value. When divergence exceeds a threshold, the system proactively diverts charging current around select cells to prevent overcharging, rather than waiting until cells reach the target voltage. This preliminary intervention eliminates the need for time-consuming low-current balancing phases at the end of charging.
Solution Approach 2:
The invention maintains continuous useful action by delivering charging current at higher rates throughout the charging process. By continuously monitoring cell voltages and dynamically diverting current around fully charged cells, the system keeps the charging process efficient and continuous, rather than reducing current to very low levels near the end of charging as in conventional methods.
2Productivity
If high charging current is delivered to all cells throughout the charging process, then charging speed is improved, but cells with lower capacity may be overcharged
Solution Approach 1:
The system applies local quality by treating each cell individually based on its specific charge state. Instead of applying uniform charging current to all cells, the system monitors each cell's voltage and selectively diverts current around cells that have reached the target charge value while maintaining high current to cells that have not yet reached target voltage. This localized current management enables both high charging speed and precise charge level control.
Solution Approach 2:
The invention implements feedback by continuously monitoring cell voltages during the charging process and using this information to dynamically adjust current distribution. When cell voltage divergence exceeds a predefined threshold, the system responds by diverting charging current around the affected cells. This real-time feedback mechanism prevents overcharging while maintaining high overall charging rates.
Data Source
AI summary
A method is provided for charging a plurality of cells in a battery pack to a target charging value. The method includes: delivering a charging current to the plurality of cells; monitoring cell voltage of each cell in the plurality of cells to determine when at least one of the cells reaches the target charging value; and diverting the charging current around the cells having reached the target charging value and cooperatively adjusting the charging current so that a current received by the cells having reached the target charging value is substantially zero.