Battery Management System Cell Balancing via Inversion
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Solution Overview
Problem
In battery packs, variations in cell capacities during manufacturing lead to uneven charge and discharge voltages, resulting in overcharging or over-discharging of specific cells, which reduces the battery pack's capacity and lifespan, and existing cell balancing methods waste energy by prioritizing the lowest voltage cell.
Innovation Solution
A battery management system comprising a master and slave management system that compares states of charge and voltage across battery packs, selectively using battery packs with higher states of charge or voltage as the operating power source, and performing cell balancing operations to maintain uniformity, thereby reducing energy loss and balancing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If cell balancing operation is performed based on lowest voltage cell, then voltage uniformity is improved, but energy loss increases
Solution Approach 1:
The patent inverts the conventional cell balancing approach by not discharging high-voltage cells but instead charging low-voltage cells to match the highest voltage cell. This reverse approach maintains voltage uniformity while avoiding energy loss from discharging functional cells, as the energy is used productively to bring lagging cells up to speed rather than wasting it through resistance heating in discharged cells.
2Stability of the object's composition
If cell balancing operation is performed, then voltage uniformity is improved, but balancing time increases
Solution Approach 1:
The patent enables continuous useful action by performing cell balancing through charging low-voltage cells during normal operation rather than requiring separate balancing cycles. The balancing process occurs continuously as part of the charging operation, eliminating idle balancing time and maintaining system productivity while achieving voltage uniformity across all cells.
3Quantity of substance
If multiple battery packs are used, then power storage capacity is improved, but voltage variation increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring the voltages of all battery packs and cells, comparing them against target values, and dynamically adjusting charging currents to maintain voltage uniformity. The master controller receives voltage information from slave controllers, determines which cells are below the target voltage, and allocates charging current accordingly to eliminate voltage variations across multiple battery packs.
Data Source
AI summary
A battery rack includes: a plurality of battery packs; a plurality of slave battery management systems, each of the slave battery management systems being coupled to a corresponding one of the battery packs, being powered by an operating power, and being configured to use the corresponding one of the battery packs for the operating power in response to receiving a corresponding one of a plurality of operating power changing signals; and a master battery management system coupled to the slave battery management systems and configured to transmit the operating power changing signals to the slave battery management systems.