Solid State Circuit Breakers for Battery Rack Current Control
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Solution Overview
Problem
Conventional methods for addressing current imbalances in battery energy storage systems, such as using DC-DC converters or fuses, are costly and inefficient, and fail to provide coordinated circuit protection against overcurrent and overtemperature events.
Innovation Solution
Deploying solid-state circuit breakers (SSCBs) that can control current and temperature in battery racks, allowing for adjustable current exchange and state-of-charge management, thereby enhancing protection and extending the life of circuit protection components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC-DC converters are used to control current to each battery rack, then current imbalance is addressed, but system cost and complexity increase significantly
Solution Approach 1:
The system divides the battery storage into multiple racks with individual circuit breakers for each rack, allowing independent current control without requiring complex DC-DC converters. This segmentation enables simple on/off control at the rack level to address current imbalance.
Solution Approach 2:
The circuit breakers are controlled dynamically based on real-time current measurements and rack conditions. The controller adjusts which racks are active or inactive to balance current distribution, providing adaptive current management without complex power electronics.
2Ease of manufacture
If conventional fuses are used for overcurrent protection, then cost is reduced, but coordinated circuit protection and selectivity cannot be achieved
Solution Approach 1:
The system incorporates current sensors and controllers that continuously monitor rack currents and provide feedback signals to the circuit breakers. This enables coordinated protection where the controller can selectively trip specific breakers based on real-time conditions, achieving selectivity that fuses alone cannot provide.
Solution Approach 2:
The circuit breakers serve multiple functions: normal current control, overcurrent protection, thermal overload protection, and coordinated selectivity. This multi-functionality replaces the need for complex fuse combinations while maintaining cost-effectiveness.
3Reliability
If battery racks are oversized to tolerate current imbalance, then current imbalance is accommodated, but system cost increases due to additional batteries
Solution Approach 1:
The system changes the operational parameters of existing battery racks by dynamically controlling which racks are active based on current conditions. This allows the system to accommodate current imbalance without adding batteries, simply by adjusting the operational state of existing racks through the controller and circuit breakers.
4Ease of manufacture
If solid state circuit breakers are deployed with on/off functionality only, then cost is reduced, but current control capability is limited
Solution Approach 1:
The controller uses periodic on/off switching of circuit breakers in a controlled sequence to achieve average current control. By rapidly switching racks on and off in a periodic manner, the system achieves effective current regulation without requiring continuously adjustable breakers, maintaining simplicity while gaining control flexibility.
Data Source
AI summary
According to one aspect of the present disclosure, an energy storage system includes one or more power sources, one or more energy storage components, and one or more solid state circuit breakers disposed between the one or more power sources and the one or more energy storage components such that electrical power is exchanged between the one or more power sources to the one or more energy storage components through the one or more solid state circuit breakers. The energy storage system also includes a controller configured to operate the one or more solid state circuit breakers to control current exchanged with the one or more energy storage components and protect the one or more energy storage components from the one or more power sources during a fault condition.