Battery Cell Voltage-Difference Control for Output Restriction
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Solution Overview
Problem
Conventional battery pack control devices impose unnecessarily large output restrictions on normal cells due to variations in cell temperatures, leading to discomfort and inefficiency.
Innovation Solution
Detect the voltage difference between the highest and lowest voltages of battery cells and execute an output restriction when the difference exceeds a predetermined threshold, thereby preventing large output restrictions on normal cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional battery pack control device uses the lowest voltage of each unit cell to determine output restriction, then over-discharging prevention is achieved, but unnecessarily large output restriction is imposed on normal cells due to temperature variations
Solution Approach 1:
The patent changes the parameter used for output restriction determination from the lowest unit cell voltage to the voltage difference between the highest and lowest unit cell voltages. This parameter change allows the system to distinguish between voltage differences caused by temperature variations (which are normal) and voltage differences caused by actual cell degradation or over-discharge risks (which require restriction), thereby maintaining battery productivity while ensuring reliability.
2Reliability
If output restriction is executed based on lowest voltage to prevent over-discharging, then battery safety is improved, but efficiency and performance are reduced due to unnecessary restrictions on normal cells
Solution Approach 1:
The patent changes the safety assessment parameter from absolute lowest voltage to voltage difference (ΔV) between highest and lowest unit cell voltages. By comparing ΔV against a threshold, the system can safely operate the battery at higher output levels when voltage differences are within normal ranges caused by temperature variations, while only imposing restrictions when voltage differences indicate actual safety concerns, thus maintaining both safety and efficiency.
3Device complexity
If the conventional control method uses total voltage and average voltage calculation, then system complexity is reduced, but measurement precision for individual cell status is insufficient
Solution Approach 1:
The patent applies segmentation by individually measuring the voltage of each unit cell rather than relying on total voltage and average calculations. This segmentation approach provides precise measurement of individual cell status, enabling the system to identify the specific cell with the highest voltage and the specific cell with the lowest voltage, thereby accurately calculating the voltage difference for safe and efficient output restriction control.
Data Source
AI summary
A method of controlling a battery having a plurality of cells is executed by a processor. The method includes detecting voltages of the plurality of cells; calculating a voltage difference between a highest voltage and a lowest voltage of the plurality of cells based on the detected voltages; and executing an output restriction on the battery when the voltage difference is equal to or greater than a predetermined first voltage difference threshold value.