Adaptive Battery Cell Balancing for Full Pack Capacity
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Solution Overview
Problem
Battery cells connected in series often suffer from cell imbalance due to variations in capacity, self-discharge, and temperature gradients, leading to limited charging and discharging capacity as the weakest cell reaches voltage limits before others, preventing full battery utilization.
Innovation Solution
A method and system for adaptive cell balancing that determines a cell balancing strategy based on battery chemistry, expected use cycle, and detected states, discharging cells to reach threshold values for voltage, state of charge, or voltage difference with a reference cell, allowing for flexible and dynamic balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive cell balancing is used to discharge individual cells to a sink, then cell imbalance is reduced, but energy is wasted and charging capacity is limited
Solution Approach 1:
A capacitor bank serves as an intermediary energy storage device between imbalanced cells. The capacitor receives excess energy from cells with higher state of charge and supplies energy to cells with lower state of charge, enabling balancing without direct discharge to sink and minimizing energy loss.
Solution Approach 2:
The system dynamically changes operating parameters including switching between different cell connections (series/parallel configurations) and adjusting charging/discharging rates based on real-time cell state monitoring. This allows optimal energy utilization while maintaining cell balance.
2Reliability
If active cell balancing with charge redistribution is implemented, then cell balance is improved, but hardware complexity and system design become more complex
Solution Approach 1:
The capacitor bank performs multiple functions: it acts as an energy buffer for active balancing, provides voltage stabilization, and enables flexible reconfiguration of cell connections. This multi-functionality reduces the need for separate dedicated balancing hardware, simplifying the overall system.
Solution Approach 2:
The system employs dynamic switching mechanisms that can reconfigure cell connections between series and parallel arrangements based on real-time balancing needs. This dynamic adaptability allows a single system architecture to handle various balancing scenarios without requiring multiple fixed configurations.
3Ease of manufacture
If cell balancing algorithm is fixed and unchanged over battery lifetime, then system design is simplified, but adaptability to different battery types and conditions is reduced
Solution Approach 1:
The cell balancing algorithm is implemented as a dynamic, adaptive system that continuously monitors cell parameters and adjusts balancing strategies in real-time. The system can adapt to different battery chemistries, aging states, and operating conditions by modifying balancing parameters based on detected cell characteristics.
Solution Approach 2:
The system incorporates continuous feedback from cell voltage, temperature, and state of charge measurements to dynamically adjust balancing operations. This feedback mechanism enables the algorithm to learn and adapt to specific battery pack characteristics over time, improving compatibility across different battery types while maintaining a unified system architecture.
Data Source
AI summary
A method of cell balancing for a battery comprising a plurality of cells. The method comprises determining a cell balancing strategy based on at least one of a cell chemistry of the battery; an expected use cycle of the battery; and a first state of the battery, wherein the first state is a detected state of the battery. The method further comprises discharging one or more cells according to the cell balancing strategy when the battery is in a second state, wherein the second state is a detected state of the battery. The cell balancing strategy is configured to discharge one or more of the plurality of cells such that a balancing parameter of each cell being discharged reaches a threshold value. The balancing parameter comprises at least one of a voltage; a state of charge; and a voltage difference.