Cross-Controlled Bypass Circuits for Series Battery String Faults
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Solution Overview
Problem
Energy storage systems with series-connected units face low operational reliability due to the risk of whole-string failure when a fault occurs in both an energy storage unit and its corresponding controller or communication unit.
Innovation Solution
The implementation of a series connection of energy storage units with multiple bypass circuits and control modules, where each control module can control its corresponding bypass circuit and at least one other, allowing for selective bypassing of faulty units even if the control module is faulty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a string of series connected energy storage units is constructed to attain high voltage and power ratings, then the energy storage system achieves high voltage and power ratings, but the operational reliability decreases because failure in a single unit or its controller results in failure of the whole string
Solution Approach 1:
The system divides the control function into multiple independent control modules, where each control module can control its own bypass circuit and at least one other bypass circuit. This segmentation ensures that a failure in one control module does not prevent bypassing of faulty energy storage units, as other control modules can take over the bypass function, thereby maintaining system reliability while preserving high power ratings through series connection.
2Ease of operation
If each energy storage unit has its own controller and protection circuit to enable selective isolation of faulty units, then the capability to isolate faulty units is improved, but the risk of whole-string failure increases when both the energy storage unit and its corresponding controller fail simultaneously
Solution Approach 1:
Each control module is designed with multi-functionality to control its corresponding bypass circuit and at least one other bypass circuit. This universal control capability ensures that if a control module fails, other control modules can still perform the bypass function for the affected energy storage unit, maintaining the selective isolation capability while reducing the risk of whole-string failure.
3Adaptability or versatility
If the protection circuit operation is controlled by the corresponding controller of each energy storage unit to enable selective bypassing, then the selective bypassing function is achieved, but the system becomes vulnerable when the controller and energy storage unit both fail
Solution Approach 1:
The system preliminarily establishes redundant control paths where each control module is pre-configured to control multiple bypass circuits. This preliminary arrangement ensures that when a controller and its corresponding energy storage unit both fail, the system can immediately activate alternative control paths without requiring complex real-time decision-making, thus maintaining the selective bypassing function while reducing vulnerability to dual failure.
Data Source
AI summary
An arrangement is disclosed, comprising a series connection of a plurality of energy storage units, a plurality of bypass circuits, each bypass circuit being configured to bypass a respective one of the energy storage units in the series connection, and a plurality of control modules, wherein each control module corresponds to a respective one of the bypass circuits. Each control module is configured to control operation of the corresponding bypass circuit and at least one other bypass circuit of the plurality of bypass circuits to selectively bypass the corresponding energy storage units in the series connection in such a way that operation of each bypass circuit of the plurality of bypass circuits to selectively bypass the corresponding energy storage unit in the series connection is controllable by means of at least two of the control modules. A related method is also disclosed.