Dual-Equilibrium Battery Balancing for Cell Capacity Mismatch
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Solution Overview
Problem
Battery packs with cells of varying capacities face issues of overcharging, over-discharging, and reduced lifespan due to imbalances, particularly in lithium-ion batteries, which are sensitive to overvoltage and require careful management to prevent damage and optimize performance.
Innovation Solution
A dual-equilibrium battery management system that combines active and passive balancing methods, using a K-Nearest Neighbor algorithm to determine when to switch between passive and active equilibrium approaches based on state of charge differences, ensuring balanced charging and discharging across cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive equilibrium battery management is used, then device complexity is reduced and cost is lowered, but productivity (balancing speed) is insufficient when cell capacity differences are large
Solution Approach 1:
The system dynamically switches between passive and active equilibrium modes based on real-time cell state assessment. The controller evaluates cell capacity differences and automatically selects the appropriate balancing mode, making the system adaptable to varying balancing needs rather than being fixed in one approach.
Solution Approach 2:
The system changes the operational parameters of the battery management system by switching between two distinct equilibrium modes. Passive equilibrium uses resistive discharge with high energy loss but low complexity, while active equilibrium uses capacitor-based energy transfer with low energy loss but high complexity, selecting based on the parameter of cell capacity difference magnitude.
2Productivity
If active equilibrium battery management is used continuously, then productivity (balancing speed) is improved, but device complexity and operation cost increase
Solution Approach 1:
The system employs dynamic mode switching where the controller continuously monitors cell states and transitions between passive and active equilibrium modes as needed. This ensures active equilibrium's high balancing speed is utilized only when necessary, rather than operating continuously at high complexity.
Solution Approach 2:
The invention extracts and isolates the complex active equilibrium functionality as a separate mode that can be activated on-demand. Rather than having the complex active balancing circuitry always engaged, the system takes out the complexity and activates it only when cell capacity differences exceed thresholds, using simpler passive balancing for routine maintenance.
3Loss of energy
If active equilibrium is used, then energy loss is reduced compared to passive equilibrium, but device complexity and initial cost increase
Solution Approach 1:
The system dynamically selects the energy-efficient active equilibrium mode only when the cell state justifies the additional complexity. The controller assesses whether the energy savings from active balancing outweigh the costs of using the more complex system, making the energy efficiency gain conditional rather than guaranteed.
Solution Approach 2:
The system changes its operational parameters by switching between two energy management approaches: passive equilibrium with high energy loss but low complexity, and active equilibrium with low energy loss but high complexity. The selection depends on parameters such as cell capacity difference magnitude and system state.
4Device complexity
If passive equilibrium is used continuously, then device complexity is minimized, but reliability is compromised when cell capacity differences are large due to insufficient balancing capability
Solution Approach 1:
The system dynamically transitions to active equilibrium mode when reliability concerns arise due to large cell capacity differences. The controller monitors balancing effectiveness and switches modes to ensure reliable operation, preventing the reliability degradation that would occur with continuous passive balancing alone.
Solution Approach 2:
The system takes preliminary action by having the active equilibrium capability ready and available, switching to it proactively when cell states indicate potential reliability issues. This preliminary preparation ensures that when large capacity differences threaten battery pack reliability, the high-performance active balancing mode is already in place to prevent damage.
Data Source
AI summary
A method and system for battery performance management that provides dual-equilibrium battery management based on the conditions of battery cells within the battery. Battery management is performed using a passive battery equilibrium approach until a condition within the battery is sensed whereby battery management is then performed using an active battery equilibrium approach.