Battery Cell Balancing via Common Bus Energy Transfer
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Solution Overview
Problem
Existing battery balancing techniques fail to ensure all cells in interconnected batteries are balanced to the same state of charge, particularly when batteries are physically separated and connected in series, leading to potential overcharging or undercharging and subsequent battery failure.
Innovation Solution
A system with a common bus and bidirectional voltage converters connected to each cell, controlled by a microcontroller that senses electrical parameters to balance cell states by transferring energy from high to low state of charge cells, ensuring all cells in a battery and across multiple batteries are balanced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If batteries are physically separated and distributed throughout the vessel, then living space is maximized and weight is balanced for proper buoyancy, but cell balancing between multiple batteries becomes difficult and unreliable
Solution Approach 1:
The patent introduces a common bus as an intermediary element that electrically connects multiple physically separated batteries. This common bus serves as a mediator through which energy can be transferred between batteries, enabling cell balancing across distributed battery locations without requiring direct physical proximity or complex communication systems.
Solution Approach 2:
The patent divides the battery system into multiple independent battery units, each with its own bidirectional converter, while maintaining connection through a shared common bus. This segmentation allows each battery to be independently managed and balanced while still achieving system-wide balancing, resolving the conflict between physical distribution and balancing reliability.
2Device complexity
If individual cell voltages are used for balancing, then the balancing circuit is simpler to implement, but cells with different capacity and internal resistance do not achieve the same state of charge
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the state of charge of cells across multiple batteries and adjusts the operation of bidirectional converters accordingly. This feedback loop ensures that cells with different capacities and internal resistances are balanced to the same state of charge, overcoming the limitations of simple voltage-based balancing while maintaining reasonable system complexity.
3Reliability
If the capacity of the worst battery determines the total system capacity, then system reliability is maintained, but the average capacity of all batteries is not utilized
Solution Approach 1:
The patent merges multiple batteries into a unified system through the common bus and controller, enabling energy transfer between batteries. This allows the system to utilize the average capacity of all batteries by dynamically redistributing energy, rather than being limited by the weakest battery. The merging of battery resources through the common bus architecture enables full system capacity utilization while maintaining reliability through continuous balancing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively balances all cells within and across batteries, ensuring they are at the same state of charge, thereby preventing overcharging or undercharging and maximizing the overall capacity of the battery system.
Implementation Method 1
Each cell is associated with a bidirectional converter that controls the flow of energy between the cell and the shared bus
Implementation Method 2
a linear current regulator arrangement which controls the amount of current that flows between the voltage converter and the common bus
Data Source
AI summary
An apparatus for balancing a plurality of cells in a battery includes common bus having a connector for connecting to a common bus of another battery. Each of plurality of balancing circuits has a bidirectional voltage converter connected to a given cell of the plurality of cells and a linear current regulator arrangement controls the magnitude of current flow between the bidirectional voltage converter. A controller is connected to the common bus and the plurality of cells and selectively operatives the plurality of balancing circuits to transfer energy between the plurality of cells and the common bus to balance the states of charge of the cells. The balancing circuits are operated in response to actual states of charge of the cells, an average state of charge, a desired voltage level for the common bus, and an actual voltage level on the common bus.