Battery Management System Self-Calibration for SoC Accuracy
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Solution Overview
Problem
Current battery management systems face challenges in providing accurate state of charge (SoC) indications due to measurement errors caused by self-leakage, temperature sensitivity, and drift over time, which are not adequately addressed by existing technologies, leading to increased manufacturing costs and time.
Innovation Solution
A battery management system that includes a charge level detector, a charge distributor, and a controller to initiate automated self-calibration of sub-unit capacities within the battery pack by discharging and charging sub-units to predetermined levels, using data acquisition circuits and microcontroller units to optimize capacity measurement and compensation for cell aging and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fuel gauging systems are used with factory-set calibration, then manufacturing cost is reduced, but measurement precision deteriorates due to drift over time and temperature
Solution Approach 1:
The battery management system performs automatic calibration using its own charge distributor and charge level detector components. The system calibrates itself by distributing charge between cells and detecting charge levels without requiring external calibration equipment, thereby improving measurement precision while avoiding the complexity of manual calibration processes
Solution Approach 2:
The system performs calibration automatically at designated times (such as when state of charge reaches 100% or 0%) before measurement drift becomes significant. This preliminary calibration action resets measurement errors and maintains accuracy throughout the battery's operational life
2Measurement precision
If manual calibration is performed at manufacture, then measurement precision is improved initially, but loss of time increases due to time-consuming calibration process
Solution Approach 1:
The battery management system performs automatic calibration using its own charge distributor and charge level detector components. The system calibrates itself by distributing charge between cells and detecting charge levels without requiring external calibration equipment, thereby improving measurement precision while avoiding the complexity of manual calibration processes
Solution Approach 2:
The system performs calibration automatically at designated times (such as when state of charge reaches 100% or 0%) before measurement drift becomes significant. This preliminary calibration action resets measurement errors and maintains accuracy throughout the battery's operational life
3Reliability
If multiple integrated circuits are used to implement battery management functions, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple battery management functions (charge distribution, charge level detection, calibration control, and state of charge calculation) into a single integrated battery management system. This merging approach maintains reliability by implementing all necessary functions while reducing the number of separate integrated circuits and interconnections required
Data Source
AI summary
Apparatus and method for battery calibration and state of charge determination (SoC) within battery packs by detecting charge levels in a cell or cells, sending the charge level information to a controller which controls the movement of charge in the battery wherein, the controller initiates the discharge of a sub-unit to a predetermined level into the other sub-units and the charging of said sub-unit in the battery to a predetermined level from the charge held on the other sub-units to improve the accuracy and reliability of battery calibration and provide an accurate State of Charge indication from battery first use to end of life.