DC Circuit Breaker Airgap Commutation for Fail-Safe Isolation
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Solution Overview
Problem
Existing DC circuit breakers are not suitable for high DC voltage systems due to the inability of airgaps to serve as reliable fail-safe mechanisms, leading to arc formation and inefficiency, and there is a need for a smaller, more cost-effective, and reliable DC circuit breaker design.
Innovation Solution
A DC solid-state circuit breaker with a power electronics section, an airgap section, and a sensing and control circuit, incorporating a fail-safe interruption circuit with a current commutation switch and overvoltage protection device, which performs controlled switching sequences to manage arc formation and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If airgap is used in DC solid-state circuit breaker for isolation, then device complexity is reduced, but reliability deteriorates because airgap cannot reliably interrupt DC current without zero crossing
Solution Approach 1:
The circuit breaker is divided into two independent sections: a power electronics section for normal operation and an airgap section for fail-safe interruption. This segmentation allows each section to have specialized functions, with the power electronics handling controlled switching and the airgap providing mechanical backup, thereby resolving the contradiction between simplified structure and reliable fail-safe mechanism.
Solution Approach 2:
A current commutation switch is introduced as an intermediary component between the power electronics and airgap sections. This mediator transfers current from the power electronics section to the airgap section during fault conditions, enabling the airgap to interrupt DC current reliably even without natural zero crossing, thus improving reliability while maintaining structural simplicity.
2Loss of energy
If higher DC voltage (380V/500V) is used for efficiency, then energy waste at AC-DC conversion is reduced, but device size and cost increase due to bulky mechanical designs
Solution Approach 1:
The invention replaces traditional mechanical circuit breaker components with solid-state power electronics for the primary switching function. The power electronics section uses semiconductor devices to interrupt current electronically without mechanical movement, dramatically reducing device size and weight while enabling efficient high-voltage DC operation, thus resolving the contradiction between energy efficiency and compact design.
3Device complexity
If traditional thermal-magnetic circuit breaker contacts are used, then device simplicity is maintained, but arc extinction becomes impossible in DC systems without zero crossing
Solution Approach 1:
Traditional mechanical contacts are replaced with solid-state power electronic switching components that can interrupt current without generating arcs. The solid-state switches use semiconductor physics rather than mechanical separation, eliminating the harmful arc phenomenon entirely while maintaining simple device design, thus resolving the contradiction between design simplicity and arc-free operation.
Solution Approach 2:
The current commutation switch acts as an intermediary that prepares the circuit for airgap interruption by transferring current in a controlled manner. This mediator enables the airgap to function reliably in DC systems by managing the current transfer process, preventing uncontrolled arc formation while maintaining overall system simplicity.
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 solution enables efficient interruption of current at DC conditions, reducing component voltage requirements and physical dimensions, resulting in a smaller, more reliable, and cost-effective DC circuit breaker design.
Implementation Method 1
The airgap section is connected in series with the power electronics section to establish a main current path
Implementation Method 2
a current commutation switch, a second solid-state switching component, and an overvoltage protection device connected in parallel with one another
Implementation Method 3
an overvoltage protection device connected in parallel with one another
Data Source
AI summary
A DC solid-state circuit breaker includes a power electronics section, an airgap section, and a sensing and control circuit. The power electronics section includes a first solid-state switching component. The airgap section is connected in series with the power electronics section to establish a main current path. The airgap section implements an isolation switch connected in series with a fail-safe interruption circuit that includes a current commutation switch, a second solid-state switching component, and an overvoltage protection device connected in parallel with one another. In response to detecting a fault event and/or an opening command, the sensing and control circuit performs a fail-safe operation that controls the isolation switch at a time period, and controls the current commutation switch and the second solid-state switching component at a delayed time period that occurs after controlling the isolation switch.