Battery Pack Dual Current Cut-Off Units
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Solution Overview
Problem
Existing battery packs fail to appropriately cut off electrical connections between the battery and external terminals when the protection element is abnormal, leading to potential damage to the battery and external devices.
Innovation Solution
A battery pack design incorporating a control unit, first and second current cut-off units, and a state determination circuit to determine the normalcy of these units, ensuring the electrical connection can be cut off even if the protection element is abnormal, using switching elements and protection circuits to inhibit current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single protection element (fuse, SCP, or FET) is used to cut off current in abnormal conditions, then the device complexity is reduced, but the reliability of current cut-off function deteriorates when the protection element itself fails
Solution Approach 1:
The single protection element is segmented into two series-connected protection elements (first and second current cut-off units). Each element can independently cut off current, providing redundant protection. If one element fails, the other can still perform the cut-off function, thereby resolving the contradiction between simplified structure and reliable protection.
2Reliability
If the control unit continuously monitors the state of protection elements during charge and discharge operations, then the reliability of protection is improved, but the loss of time for charge/discharge operations increases due to frequent state checking
Solution Approach 1:
The control unit performs preliminary state determination of the protection elements during idle periods or at specific intervals rather than continuously during charge/discharge operations. This preliminary checking approach ensures protection reliability while minimizing interference with charge/discharge timing, resolving the contradiction between monitoring reliability and operational efficiency.
Data Source
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AI summary
A battery pack (40, 140, 240) of one aspect of an embodiment of the present disclosure comprises a battery (50), a control unit (60), a pair of external terminals (44A, 44B, 46D), a first current cut-off unit (70), and a second current cut-off unit (72, 172). The control unit (60) determines whether the first current cut-off unit (70) and the second current cut-off unit (72, 172) are normal or abnormal when neither charge nor discharge of the battery (50) is performed. When the first current cut-off unit (70) and the second current cut-off unit (72, 172) are both normal, the control unit (60) turns the first current cut-off unit (70) and the second current cut-off unit (72, 172) to an energized state. When at least one of the first current cut-off unit (70) and the second current cut-off unit (72, 172) is abnormal, the control unit (60) turns the first current cut-off unit (70) or the second current cut-off unit (72, 172) to a cut-off state.