Battery Cell Charge Equalization Circuit with Hysteresis Control
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Solution Overview
Problem
Multi-cell batteries face performance degradation and premature failure due to uneven charging and aging of cells, leading to overcharging, temperature buildup, and reduced cycle life, as well as the need for costly and time-consuming replacement of entire batteries when a single cell fails.
Innovation Solution
A battery cell charge equalization system that uses a circuit to monitor and divert excess charging current away from cells with higher states of charge, employing a reference amplifier and switching elements to set thresholds and provide hysteresis, ensuring balanced charging and extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If batteries are made up of multiple cells in series to achieve higher operating voltages, then the operating voltage is improved, but the reliability deteriorates due to uneven charging and aging of cells causing overcharging and premature failure
Solution Approach 1:
The patent divides the battery system into individual cell monitoring units, with each cell having its own voltage detection and control circuitry. This segmentation allows independent monitoring and control of each cell's charging process, preventing one cell's degradation from affecting the entire battery's reliability while maintaining high operating voltage through series connection.
2Productivity
If charging current is continued to all cells until full charge, then the charging speed is improved, but the reliability deteriorates due to overcharging of degraded cells causing temperature and pressure buildup
Solution Approach 1:
The patent implements preliminary detection of each cell's voltage state before charging begins and during the charging process. The detection circuitry identifies cells that have reached their voltage threshold before other cells, allowing the control system to preemptively adjust or stop charging to that specific cell, preventing overcharging, temperature buildup, and pressure issues while maintaining efficient charging of other cells.
3Reliability
If the entire battery is replaced when a single cell fails, then the reliability is restored, but the cost and time consumption increase significantly
Solution Approach 1:
The patent's independent cell monitoring and control architecture enables identification and isolation of individual failed cells without affecting the operation of other cells. This segmentation allows for selective replacement or repair of only the defective cell rather than the entire battery assembly, dramatically reducing replacement time and cost while restoring battery reliability.
4Measurement precision
If voltage threshold monitoring is implemented for each cell, then the charging precision is improved, but the device complexity increases due to additional circuitry
Solution Approach 1:
The patent combines multiple functions into integrated circuit modules that simultaneously perform voltage detection, threshold comparison, and charging control for each cell. By merging these functions into unified control units rather than separate discrete circuits, the system achieves precise voltage monitoring for each cell while minimizing the increase in overall device complexity through functional integration.
Data Source
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AI summary
Battery cell charge equalization devices, systems and methods are provided. A particular method includes receiving a charging current at a battery charge equalization circuit coupled to a battery cell of a multi-cell battery. The method also includes routing at least a portion of the charging current away from the battery cell when a voltage of the battery cell satisfies a first voltage threshold. The method further includes establishing a second voltage threshold in response to the voltage of the battery cell satisfying the first voltage threshold. The second voltage threshold is lower than the first voltage threshold. The charging current is routed away from the battery cell while the voltage of the battery cell satisfies the second voltage threshold.