Battery Management Voltage Fault Detection Using RC Time Constants
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Solution Overview
Problem
Conventional methods for detecting abnormalities in battery management systems are inaccurate, leading to incorrect protection operations due to incomplete diagnosis of voltage measurement issues.
Innovation Solution
A method involving a control unit, measure unit, monitoring resistors, capacitors, and switches is used to calculate and compare theoretical and measured time constants, determining if the battery management system is abnormal by assessing voltage values and capacitance over specific time periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the voltage value on a capacitor is compared with the cell tap open threshold to determine voltage accuracy, then the detection process is simple, but the diagnosis is incorrect and leads to wrong protection operations
Solution Approach 1:
The patent changes the detection parameter from simple voltage comparison to time constant measurement. By measuring the charging and discharging time constants of the capacitor through controlled switching sequences and voltage measurements at specific time points, the system achieves more accurate diagnosis of connection abnormalities while maintaining a systematic detection process.
2Ease of manufacture
If conventional voltage comparison method is used, then the detection method is straightforward, but it cannot detect abnormalities caused by component degradation or connection resistance changes
Solution Approach 1:
The patent employs periodic switching actions to charge and discharge the capacitor in controlled cycles. By repeatedly switching the switch between on and off states and measuring voltage at specific time points in each cycle, the system can detect abnormalities in connection resistance and component degradation that static voltage comparison cannot identify.
3Measurement precision
If the battery management system uses accurate abnormality detection, then protection operations are correct, but the detection process becomes complex requiring multiple measurements and calculations
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the charging and discharging time constant measurement framework. The control unit is pre-programmed with the switching sequences and measurement timing, so that when detection is needed, the system simply executes the predetermined sequence rather than performing complex real-time analysis, thus achieving accurate detection with manageable complexity.
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
This approach accurately identifies abnormalities in the battery management system, preventing incorrect protection operations and improving detection accuracy compared to conventional methods.
Implementation Method 1
a first capacitor, a first switch and a first balance resistor... controlling, using the control unit, the first switch to successively turn off for a first time period, turn on for a second time period, and turn off for a third time period; controlling, using the control unit, the measure unit to measure a voltage value on the first capacitor
Implementation Method 2
calculating, using the control unit, a value of a theoretical time constant corresponding to the first cell; determining, using the control unit, a value of a measured time constant according to at least one of the measured capacitance voltage values and the measured voltage value of the first cell
Data Source
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AI summary
A method for detecting whether a battery management system is abnormal includes: calculating a value of a theoretical time constant corresponding to a first cell; determining a preset range of the theoretical time constant; controlling a first switch to turn off for a first time period, turn on for a second time period, turn off for a third time period; measuring a voltage on a first capacitor at end of first time period, to produce a measured voltage of first cell; measuring voltages on first capacitor at least at one time point in third time period, to produce measured capacitance voltages; determining a value of a measured time constant according to at least one of measured capacitance voltages and the measured voltage of first cell; and determining the battery management system is abnormal, if the value of the measured time constant exceeds the preset range of the theoretical time constant.