Battery Defect Diagnosis Using Dynamic Resistance Thresholds
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Solution Overview
Problem
Existing methods for diagnosing defects in batteries with multiple connected cells are inaccurate due to structural limitations, memory constraints in Battery Management Systems (BMS), and environmental factors affecting internal resistance measurements.
Innovation Solution
A server-based method that calculates moving averages and band thresholds using historical resistance values, adjusted for environmental conditions, to accurately diagnose battery cell defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed reference value is used for DCIR comparison, then the diagnosis method is simple, but it cannot detect defects when multiple battery cells are disconnected or shorted simultaneously
Solution Approach 1:
The patent replaces the fixed reference value with a dynamic reference value that changes over time. The reference value is updated based on the battery's aging state and operational history, allowing the diagnosis system to adapt to changing battery conditions. This dynamic approach enables accurate detection of defects even when multiple cells are compromised, as the reference value reflects the battery's current state rather than remaining static.
Solution Approach 2:
The patent implements a feedback mechanism where the diagnosed aging state is fed back into the system to update the reference value. The control unit continuously monitors battery performance and uses this information to adjust the reference value for subsequent diagnoses. This feedback loop ensures that the reference value remains accurate and up-to-date, improving defect detection capability while maintaining system simplicity.
2Ease of manufacture
If DCIR-based diagnosis is used, then the method is easy to implement, but the error range becomes too large when external temperature changes rapidly
Solution Approach 1:
The patent addresses temperature sensitivity by changing the parameter used for diagnosis from raw DCIR values to an adjusted reference value that compensates for temperature effects. The system monitors temperature conditions and adjusts the reference value accordingly, allowing accurate defect detection across a wide temperature range while maintaining the simplicity of DCIR-based measurement.
Solution Approach 2:
The patent introduces an intermediary adjustment mechanism between the DCIR measurement and the final diagnosis. The reference value acts as an intermediary that mediates between the raw measurement and the diagnostic conclusion, compensating for temperature and aging effects. This intermediary approach maintains the ease of DCIR measurement while improving accuracy under varying environmental conditions.
3Measurement precision
If high-precision defect diagnosis requiring large cumulative data is implemented, then diagnosis accuracy is improved, but it cannot be easily implemented with small memory capacity in BMS
Solution Approach 1:
The patent extracts only the essential information needed for accurate diagnosis from the vast amount of available battery data. Instead of storing and analyzing all cumulative data, the system selectively extracts and stores only the necessary parameters (such as voltage, current, temperature, and DCIR values at specific intervals) required for calculating the reference value. This extraction approach maintains high diagnosis accuracy while dramatically reducing memory requirements.
Solution Approach 2:
The patent applies partial action by using a limited, representative sample of data points rather than all available cumulative data. The system stores and analyzes only the necessary portion of historical data (e.g., data at specific time intervals or under specific conditions) to establish the reference value. This partial approach provides sufficient accuracy for defect detection while keeping memory usage within acceptable limits for BMS.
4Measurement precision
If direct sensing of individual battery cell voltage is attempted, then cell-level diagnosis is possible, but structural connection problems prevent easy implementation
Solution Approach 1:
The patent uses battery-level DCIR measurement as an intermediary to indirectly assess individual cell conditions. Instead of directly measuring each cell's voltage (which requires complex wiring and access), the system measures the overall battery DCIR and uses this intermediary value to infer the state of individual cells. The reference value then serves as a mediator to identify which cells may be defective, providing cell-level diagnosis capability through a simpler battery-level measurement approach.
Data Source
AI summary
The present invention provides a server for diagnosing a defect in a battery, the server including a server communication unit configured to receive battery data including at least one of a battery voltage, a battery current, and a battery temperature, which is a temperature of the battery, from a battery management system (BMS); a server storage unit configured to store a plurality of internal resistance values of the battery calculated based on the battery data at each diagnosis time point for diagnosing the defect in the battery; and a server control unit configured to extract a plurality of previous diagnosis time points corresponding to a predetermined number of samples based on a diagnosis time point, calculate a moving average, compare an internal resistance value with an upper band threshold, and a lower band threshold, and diagnose the defect in the battery.