Hybrid Circuit Breaker With Current Injection for Arc-Free DC Interruption
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Solution Overview
Problem
Traditional circuit breakers are ineffective in reliably interrupting DC fault currents in high-voltage DC power systems due to the lack of zero crossings, leading to significant power losses and self-heating.
Innovation Solution
A hybrid circuit breaker with a mechanical switch and a parallel electronic switch path, utilizing a current injector and transient commutation current injection circuit to quickly transfer fault currents from the mechanical to the electronic path, minimizing arcing and power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a series auxiliary commutation power electronic switch is used in the main current conduction path, then DC fault current interruption is achieved, but significant power losses and self-heating occur
Solution Approach 1:
The circuit breaker is divided into two separate parallel current paths: a mechanical switch path for normal operation and an electronic switch path for fault interruption. This segmentation allows each component to operate in its optimal mode without continuous power losses
Solution Approach 2:
The mechanical switch opens in advance before the fault current reaches peak values, transferring the current to the electronic path. This preliminary action prevents the mechanical switch from having to interrupt high-current arcs, reducing power losses
2Reliability
If a series auxiliary commutation power electronic switch is used in the main current conduction path, then DC fault current interruption is achieved, but self-heating increases
Solution Approach 1:
The circuit breaker is divided into two separate parallel current paths: a mechanical switch path for normal operation and an electronic switch path for fault interruption. This segmentation allows each component to operate in its optimal mode without continuous power losses
Solution Approach 2:
The electronic switch operates periodically only during fault conditions rather than continuously, minimizing self-heating by being active only when necessary for fault current interruption
3Device complexity
If traditional electromechanical circuit breakers are used, then mechanical simplicity is maintained, but reliable DC fault current interruption fails
Solution Approach 1:
The invention merges two different switching technologies: a mechanical switch for normal operation and a power electronic switch for fault interruption. This hybrid combination leverages the advantages of both technologies to achieve reliable DC fault current interruption while maintaining mechanical simplicity during normal operation
Solution Approach 2:
A current transfer switch acts as an intermediary between the mechanical and electronic paths, enabling seamless current transfer from the mechanical path to the electronic path during fault conditions, thus bridging the gap between mechanical simplicity and electronic reliability
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 hybrid circuit breaker effectively interrupts fault currents without arcs and reduces power losses by using a transient commutation current injection circuit to rapidly switch fault currents from the mechanical to the electronic path, enhancing reliability and efficiency in DC power systems.
Implementation Method 1
The current injector can be or comprises a transient commutation current injection circuit
Data Source
Figure 1
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Figure 3A~3B
AI summary
A circuit breaker and method of operation. The circuit breaker includes a first current path including a mechanical switch, such as an ultrafast mechanical switch, and a second current path in parallel connection to the first current path, and including a current injector, such as a transient commutation current injection circuit, in series with bidirectional power electronic switch. A short circuit fault current from a mechanical switch path is communicated to the electronic path via a current injection, followed by interrupting the fault current. A pulse current is generated to the electronic switch in the second current path, and the mechanical switch is opened during the pulse current. The pulse current and the electronic switch reduce or eliminate arcing upon the opening the mechanical switch.