Hybrid Energy Storage Module Control for SOC Balancing
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Solution Overview
Problem
In electrical systems with hybrid power storage devices, the variation in efficiency among energy storage modules can cause the state of charge to diverge, leading to overvoltage conditions and the need to disconnect power storage devices or stacks for rebalancing, which limits system operation.
Innovation Solution
A hybrid energy storage module (HESM) system with a controller that manages the connectivity of energy storage modules to a power bus, allowing for short circuit mode, discharge mode, and SOC balancing mode to maintain balanced state of charge across power stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If energy storage modules operate in a stack with varying efficiency, then the system can accommodate different operating conditions, but the state of charge diverges causing overvoltage conditions and requiring disconnection for rebalancing
Solution Approach 1:
The system divides the energy storage stack into multiple independently controllable power stages, each with its own controller and switching mechanism. This segmentation allows individual stages to be managed separately, enabling selective disconnection and charging of specific stages without affecting the entire stack, thus preventing state of charge divergence while maintaining overall system adaptability.
Solution Approach 2:
The system dynamically adjusts the connectivity and operation of each power stage based on real-time state of charge measurements and operating conditions. Controllers continuously monitor and modify the operational state of individual stages, enabling adaptive rebalancing and preventing overvoltage conditions while maintaining system versatility across different operating scenarios.
2Reliability
If power storage devices are disconnected for state of charge rebalancing, then overvoltage conditions are prevented, but system operation is limited and functionality is unavailable
Solution Approach 1:
By segmenting the stack into independently controllable power stages, the system can isolate and rebalance only the specific stage experiencing state of charge divergence, rather than disconnecting the entire stack. This maintains productivity by keeping other stages operational while preventing overvoltage conditions in the affected stage.
Solution Approach 2:
The system enables continuous operation by allowing rebalancing to occur in selected power stages while other stages continue to provide energy storage functionality. The dynamic control ensures that useful action (energy storage and delivery) continues uninterrupted in healthy stages, maintaining overall system productivity during rebalancing operations.
3Power
If hybrid power storage devices are grouped by type and connected in stages, then pulses can be absorbed and sourced to the electrical system, but efficiency variation causes state of charge divergence
Solution Approach 1:
The system segments the hybrid power storage devices into distinct power stages with independent control, allowing each stage to contribute to pulse absorption and sourcing while enabling separate monitoring and management of state of charge. This segmentation maintains the power capability of handling pulses while preventing state of charge divergence through individual stage control.
Solution Approach 2:
The system implements feedback control by continuously monitoring the state of charge of each power stage and using this information to dynamically adjust the operation of individual stages. This feedback mechanism ensures that pulse absorption and sourcing activities are coordinated across stages to maintain state of charge consistency while preserving the overall power capability of the hybrid system.
Data Source
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AI summary
A hybrid energy storage module system includes a first power stage (102) having a short circuit switch to connect the first power stage to a power bus, a second power stage (104) stacked in series with the first power stage and having a short circuit switch to connect the second power stage to the power bus, and a controller (112). The controller is operably connected to the first and second power stage short circuit switches to discharge one of the first and second power stage through the other of the first and second power stage in a state of charge balancing mode. Aircraft electrical systems and methods of controlling connectivity of hybrid energy storage modules to electrical systems are also described.