Battery Voltage Sensing Circuit for Fast Line Disconnection Detection
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Solution Overview
Problem
Existing methods for detecting disconnection in voltage measurement lines of battery assemblies require multiple balance adjustment circuits, taking a long time and necessitating a large number of IC ports, which is inefficient and costly.
Innovation Solution
A voltage measurement circuit with low-pass filters and discharge circuits connected between adjacent voltage measurement lines, using a control circuit to quickly diagnose disconnection by monitoring voltage changes after switching, reducing the need for additional hardware and ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple balance adjustment circuits sequentially operate to detect disconnection, then disconnection detection can be performed, but detection time becomes excessively long
Solution Approach 1:
The discharge circuit is activated before the voltage measurement is performed. By pre-discharging the capacitor connected to the voltage measurement line, the system creates a known initial state that enables rapid detection. When a disconnection occurs, the voltage on the pre-charged capacitor immediately reflects the abnormality, allowing detection within a single measurement cycle rather than requiring sequential operations across multiple cycles.
2Reliability
If multiple balance adjustment circuits are used for disconnection detection, then detection accuracy is maintained, but the number of IC ports required increases significantly
Solution Approach 1:
The discharge circuit serves multiple functions: it performs cell balancing by discharging overcharged cells and simultaneously enables disconnection detection by pre-charging the measurement line capacitor. This dual functionality eliminates the need for separate detection circuits, reducing the number of IC ports required while maintaining detection accuracy through the voltage changes produced during the balancing operation.
3Reliability
If sequential operation of balance adjustment circuits is used, then disconnection can be identified, but processing speed and productivity decrease
Solution Approach 1:
The voltage measurement line remains continuously charged through the discharge circuit operation, eliminating idle periods between measurement cycles. The capacitor is continuously maintained at the appropriate voltage level, allowing the system to perform both balancing and detection operations in parallel without sequential waiting, thereby maintaining high processing speed and productivity while ensuring reliable abnormality identification.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for rapid detection of voltage measurement line abnormalities with reduced costs and minimal impact on battery operation, enabling efficient disconnection diagnosis during charging, discharging, or cell balancing.
Implementation Method 1
a plurality of capacitors connected between two adjacent voltage measurement lines among the plurality of voltage measurement lines and between the ground line and a voltage measurement line of the lowest cell among the plurality of voltage measurement lines, respectively, the plurality of capacitors constituting low-pass filters with the plurality of input resistors, respectively
Implementation Method 2
a plurality of discharge circuits connected between the two adjacent voltage measurement lines and between the ground line and the voltage measurement line of the lowest cell at respective nodes which are closer to the voltage measurement circuit than the low-pass filters
Data Source
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AI summary
A voltage measurement circuit is configured to measure voltages of cells connected in series to one another. Input resistors are connected to voltage measurement lines, respectively. Capacitors are connected between two lines of the voltage measurement lines. Discharge circuits are connected between the lines at respective nodes closer to a voltage measurement circuit than a low-pass filter. A control circuit is configured to turn off a switch of a certain channel at a predetermined time after turning on the switch of the certain channel. When a voltage of a channel immediately upper than the certain channel exceeds a threshold voltage when a predetermined period of time elapses from the turning off of the switch, the control circuit is configured to determine that an abnormality occurs in a voltage measurement line among the plurality of voltage measurement lines between the certain channel and the channel immediately upper than the certain channel.