Battery Internal Resistance Diagnosis for Parallel Cell Defects
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Solution Overview
Problem
Existing battery diagnosis methods struggle to accurately diagnose defects in batteries with multiple cells connected in parallel due to structural challenges, misdiagnosis of direct current internal resistance (DCIR) values, and inaccuracies from rapid temperature changes and state of charge (SOC) variations.
Innovation Solution
A battery diagnosis apparatus and method that measures battery voltage, current, and temperature, calculates moving averages and standard deviations, and sets dynamic band thresholds based on environment data to accurately diagnose defects by comparing internal resistance values with upper and lower thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a plurality of battery cells is connected in parallel to increase battery capacity, then the battery capacity increases, but it becomes difficult to directly sense the cell voltages of individual battery cells due to structural problems
Solution Approach 1:
The patent introduces an intermediary measurement approach by measuring the total battery voltage across the parallel connection group and using this as a basis for inferring individual cell states. Instead of directly measuring each cell's voltage (which is structurally difficult), the system uses the easily measurable total voltage combined with current and temperature data to calculate internal resistance and diagnose individual cell defects indirectly.
2Device complexity
If direct current internal resistance (DCIR) diagnosis is performed by comparing with a fixed reference value, then the diagnosis process is simple, but it cannot detect defects when multiple battery cells are disconnected or short-circuited at the same time
Solution Approach 1:
The patent transitions from a static fixed reference value approach to a dynamic diagnosis method. The system continuously monitors battery voltage, current, and temperature to calculate real-time internal resistance values. By comparing these dynamic measurements with dynamically updated reference ranges that account for aging and environmental changes, the system can reliably detect defects even when multiple cells fail simultaneously.
3Device complexity
If DCIR diagnosis is performed using a fixed reference value, then the method is simple to implement, but misdiagnosis occurs due to aging and rapid temperature changes
Solution Approach 1:
The patent applies parameter changes by making the reference values dynamic rather than fixed. The system adjusts reference internal resistance values based on temperature changes and battery aging states. By continuously updating the measurement parameters (voltage, current, temperature) and comparing them with adaptively adjusted reference ranges, the diagnosis accuracy is maintained across varying environmental conditions and battery lifecycles.
4Quantity of substance
If the number of battery cells increases to achieve high capacity, then the battery capacity increases, but the risk of defects such as disconnection or short between battery cells increases
Solution Approach 1:
The patent implements a feedback-based diagnosis system that continuously monitors battery performance parameters (voltage, current, temperature) and uses this feedback to detect defects. By calculating internal resistance from these measurements and comparing it with reference values, the system provides continuous feedback on battery health, enabling early detection of defects in high-capacity batteries with numerous cells.
Data Source
AI summary
One aspect of the present disclosure includes a battery diagnosis apparatus including a measuring unit configured to measure a battery voltage, a battery current, and a battery temperature, a storage unit configured to store a plurality of internal resistance values calculated based on the battery voltage, the battery current, and an environment data item, which is a factor affecting an internal resistance value, at each diagnosis time of diagnosing defects of the battery, and a control unit configured to extract, at each diagnosis time, a plurality of diagnosis times, and a second condition that the plurality of diagnosis times are previous diagnosis times, calculate a moving average, and diagnose the defects of the battery by comparing the internal resistance value with an upper band threshold larger than the moving average by a predetermined value and a lower band threshold smaller than the moving average by a predetermined value.