Cell Balancing Device Using Voltage Rate of Change
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Solution Overview
Problem
Existing energy storage systems face inefficiencies in cell balancing, particularly in managing voltage differences and state of charge across battery cells, which affects overall system performance and capacity utilization.
Innovation Solution
A method and device for cell balancing that includes a battery management system (BMS) and cell balancing circuit, which measure voltages and temperatures, calculate state of charge, and perform active or passive cell balancing to equalize cell voltages, optimizing charging and discharging characteristics across multiple battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell balancing is performed based only on voltage difference threshold, then cell balancing can be initiated, but balancing efficiency is low and time-consuming
Solution Approach 1:
The patent changes the balancing decision parameter from simple voltage difference to a composite parameter incorporating voltage difference, state of charge difference, and charging/discharging rate. This multi-parameter approach enables more accurate identification of cells requiring balancing, improving balancing efficiency and reducing time consumption by avoiding unnecessary balancing operations.
2Stability of the object's composition
If cell balancing is performed frequently to maintain voltage equality, then voltage uniformity improves, but energy loss increases
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors voltage difference, state of charge difference, and charging/discharging rate to dynamically adjust balancing decisions. This feedback approach ensures voltage uniformity is maintained only when necessary, preventing excessive balancing operations and reducing associated energy losses while still achieving stable voltage distribution.
3Ease of manufacture
If passive cell balancing is used to equalize cell voltages, then implementation is simple, but energy loss is high
Solution Approach 1:
The patent introduces state of charge and charging/discharging rate as additional parameters to determine when passive cell balancing should be activated. By evaluating these parameters alongside voltage difference, the system optimizes the activation conditions for passive balancing, reducing unnecessary operations and minimizing energy loss while maintaining implementation simplicity.
4Productivity
If cell balancing is based on state of charge calculation, then capacity utilization improves, but measurement and calculation complexity increases
Solution Approach 1:
The patent makes the battery management system perform multiple functions: voltage monitoring, state of charge calculation, charging/discharging rate measurement, and balancing decision-making. By integrating these functions into a unified system, the patent achieves improved capacity utilization through state of charge-based balancing while minimizing the increase in overall system complexity.
Data Source
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AI summary
A method of balancing a plurality of battery cells comprises determining an open circuit voltage OCV of at least one of the battery cells, determining a rate of change of the open circuit voltage at a given state of charge of the battery cell from a function that defines the relationship between the open circuit voltage and the state of charge and initiating cell balancing if the rate of change is greater than a reference value.