Battery Pack Disconnection Detection via Short-Circuiting Nodes
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Solution Overview
Problem
Conventional battery packs face challenges in detecting disconnections at intermediate taps due to voltage division by internal resistors, leading to difficulty in identifying overcharge states and increased loss when using pull-up or pull-down resistors, which complicates the detection of connection line disconnections.
Innovation Solution
A battery pack design incorporating a voltage detector, charge/discharge controller, short-circuiting section, and disconnection detector that short-circuits nodes between cells to detect deviations in voltages, allowing for reliable disconnection detection and preventing overcharge by controlling the short-circuiting section based on voltage states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pull-up resistor or pull-down resistor is used to detect intermediate tap disconnection, then disconnection detection is enabled, but energy loss occurs in steady state
Solution Approach 1:
The patent employs periodic switching of the short-circuiting section between conductive and non-conductive states to enable disconnection detection without continuous energy consumption. The detection is performed intermittently by controlling the switching element to short-circuit the intermediate tap to a reference potential at specific intervals, rather than maintaining continuous connection with resistors.
2Loss of energy
If resistance value of pull-up resistor or pull-down resistor is increased to reduce loss, then energy loss is reduced, but detection precision deteriorates
Solution Approach 1:
The patent introduces a switching element as an intermediary between the intermediate tap and the reference potential. This switching element enables precise detection by controllably connecting the intermediate tap to a stable reference potential during detection periods, providing a clear voltage signal difference that enhances detection precision without requiring high-value resistors.
3Reliability
If double protection IC is provided for detecting terminal voltages, then protection capability is enhanced, but disconnection detection becomes more difficult due to voltage division by internal resistors
Solution Approach 1:
The patent performs preliminary action by controlling the switching element to short-circuit the intermediate tap to a reference potential before voltage measurement. This preliminary short-circuiting establishes a known reference state that eliminates the voltage division effect caused by internal resistors in the double protection IC, enabling accurate disconnection detection despite the presence of these resistors.
4Reliability
If short-circuiting section is continuously conducted to detect disconnection, then detection reliability is improved, but energy loss increases
Solution Approach 1:
The patent implements periodic action by controlling the short-circuiting section to operate in alternating conductive and non-conductive states. The switching element is activated at specific intervals to perform detection, maintaining high detection reliability through regular monitoring while minimizing energy loss by keeping the short-circuiting section inactive during normal operation periods.
Data Source
AI summary
The battery pack includes an assembled battery including a plurality of secondary battery cells connected at least in series; a voltage detector which detects a terminal voltage of each of the plurality of secondary battery cells; a charge/discharge controller which controls charge/discharge of the assembled battery based on the terminal voltage of each cell detected by the voltage detector; a short-circuiting section which short-circuits a node between cells to the high voltage side or the low voltage side of a power line, or which short-circuits nodes between the cells to each other; and a disconnection detector which controls conduction/non-conduction of the short-circuiting section and which detects a disconnection of the connection line from the voltage detector to the node between the cells, based on a state of controlling the conduction/non-conduction, and at least one of a voltage at the node between the cells detected by the voltage detector, a voltage of the high voltage side or the low voltage side of the power line, and a terminal voltage of each cell. The floating (disconnection) of intermediate taps of the secondary battery cells can be reliably detected without causing losses in regular processes.