Battery Pack Voltage Variance Reduction via Dynamic Cell Module Switching
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Solution Overview
Problem
Battery packs face issues with voltage variance and potential catastrophic failures due to individual cell failures or increased loading, leading to service interruptions and high replacement costs, as existing solutions fail to maintain low voltage variance across varying load conditions.
Innovation Solution
A cell stack configuration with series and shunt switches, monitored by a stack monitor circuit, allows for selective contribution or bypass of cell modules to maintain stable operating voltage, using thermal fuses for protection and minimizing voltage variance by dynamically adjusting module contributions based on measured parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stack operating voltage is boosted to remain above minimum voltage during heavy loads, then the voltage stability is improved, but the voltage during light loading excessively increases causing high voltage variance
Solution Approach 1:
The patent implements dynamic voltage regulation by switching between different cell module configurations based on load conditions. The system transitions from a fixed series configuration to a dynamic configuration that can parallelize cell modules when needed, allowing the voltage to adapt automatically to load requirements without excessive variance.
Solution Approach 2:
The patent changes the electrical configuration parameters of the cell modules by switching between series and parallel connections. This parameter change allows the system to adjust the effective voltage and current delivery characteristics to match load demands, preventing both voltage drops during heavy loads and excessive voltage during light loads.
2Reliability
If one battery cell is isolated for conditioning, then the reliability of remaining cells is improved, but the voltage variance increases during conditioning and varying load conditions
Solution Approach 1:
The patent segments the cell stack into multiple independent cell modules, each with its own series and shunt switches. This segmentation allows individual modules to be conditioned or bypassed without affecting the entire stack, and enables flexible reconfiguration to maintain voltage stability during conditioning operations.
Solution Approach 2:
The patent uses dynamic switching between series and parallel configurations of cell modules during conditioning. When one cell is isolated, the system can reconfigure remaining modules to maintain appropriate voltage levels, preventing excessive voltage variance during conditioning and load variations.
3Adaptability or versatility
If series switches and shunt switches are added to enable selective configuration of cell modules, then the voltage control capability is improved, but the device complexity increases
Solution Approach 1:
The patent divides the cell stack into modular units, each with integrated series and shunt switches. This segmentation distributes the switching complexity across multiple simple modular units rather than requiring a single complex switching system, making the overall control more manageable and reliable.
Solution Approach 2:
The patent designs the cell modules with universal switching capabilities that can perform multiple functions: normal operation, cell isolation, module parallelization, and voltage regulation. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing complexity while maintaining high adaptability.
Data Source
AI summary
In one aspect, there is disclosed a cell stack which can include cell modules connected in series to generate a stack operating voltage. The cell modules can include a battery cell in series with a series switch and include a shunt switch connected in parallel to the battery cell and the series switch. A stack monitor circuit can have a series control coupled to the series switch, a shunt control coupled to the shunt switch, and a battery cell monitor coupled to the battery cell for measuring a cell parameter from each cell module. Based on the measured cell parameter, the stack monitor circuit can select at least one cell module either to contribute to the stack operating voltage by closing the series switch and opening the shunt switch or to bypass the stack operating voltage by the opening the series switch and closing the shunt switch.