Battery Cell SoH-Based Disconnection for Balanced Pack Aging
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Solution Overview
Problem
Existing battery management systems primarily focus on balancing State of Charge (SoC) between individual cells, neglecting the underlying State of Health (SoH) imbalances, which can lead to inefficiencies and reduced battery system performance due to unequal cell degradation and operating conditions.
Innovation Solution
A method that measures and compares SoH of each cell, selectively disconnecting cells with better or poorer health during charging and discharging cycles to maintain balanced SoH, thereby addressing the root cause of SoC imbalances and ensuring even cell usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cell bypass methodologies (passive balancing) are used to equalize SoC, then implementation simplicity and low cost are improved, but energy losses increase due to resistive dissipation
Solution Approach 1:
The patent replaces passive resistive balancing (mechanical/electrical dissipation) with active switching circuitry that transfers charge between cells through capacitive coupling, substituting energy-dissipating mechanisms with energy-conserving electronic control
Solution Approach 2:
The patent changes the balancing approach from continuous resistive discharge to periodic switching operations, altering the temporal and electrical parameters of the balancing process to achieve equalization with minimal energy loss
2Object-affected harmful factors
If cell to cell balancing methodologies are used, then voltage and current stress is reduced, but device complexity increases
Solution Approach 1:
The patent divides the battery pack into multiple modular string units, each with its own switching network, allowing independent balancing of individual cells within each string while sharing control resources across the system
Solution Approach 2:
The patent employs dynamic switching networks that can reconfigure connections between cells based on real-time SoC measurements, enabling flexible low-stress balancing paths to be created adaptively rather than using fixed complex circuitry
3Productivity
If switched capacitor methodologies are used for cell balancing, then balancing efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent designs switching networks that serve multiple functions: cell balancing, cell isolation for replacement, and system reconfiguration, allowing a single hardware architecture to perform multiple battery management tasks without requiring separate dedicated circuits for each function
Solution Approach 2:
The patent combines the balancing switch network with the cell isolation and monitoring infrastructure, merging multiple battery management functions into a unified control architecture that reduces overall system complexity despite the advanced balancing capabilities
Data Source
AI summary
A method of battery management for managing a number of cells (2) comprising at least one set of cells (2) that are interconnectable in series to form a battery (5, 5′ 5″). The method comprises measuring parameters relating to the state of health, SoH, or of each cell (2) of said number of cells (2). The SoH of each cell (2) in said set of cells (2) are compared and at least one cell (2) having a poorer state of health than the remainder of the cells (2) and at least one cell (2) having a better state of health than the remainder of the cells (2) is identified. If a maximum state of charge, SoCmax, threshold has been reached for the at least one cell (2) having a better state of health during a charging cycle it is disconnected. If a minimum state of charge, SoCmin, threshold has been reached for the at least one cell (2) having a poorer state of health during a discharging cycle it is disconnected.