DC Circuit Breaker Topology for Selective Fault Tripping
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Solution Overview
Problem
Existing DC voltage circuit breakers face challenges in selective tripping and current management, leading to overdimensioning and high costs due to the desaturation behavior of semiconductor switches, which can cause unintended energy discharge and high currents during faults.
Innovation Solution
A circuit breaker device combining a safety fuse with a unidirectional semiconductor switch and a diode, integrated with a current sensor and control device, to manage current flow and tripping selectively, ensuring efficient isolation and reduced power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a controllable semiconductor switching element is used in a DC voltage circuit breaker, then the switching speed and controllability are improved, but the desaturation behavior causes unintended energy discharge and high currents during faults, leading to overdimensioning and increased costs
Solution Approach 1:
The patent segments the switching function into two separate components: a semiconductor switching element for normal operation and a safety fuse for fault conditions. This segmentation allows each component to be optimized for its specific function, with the semiconductor providing fast switching and the fuse providing reliable fault isolation without desaturation effects.
Solution Approach 2:
The patent introduces a parallel diode as an intermediary component that works together with the semiconductor switching element. The diode provides a controlled path for current during switching transitions and fault conditions, preventing uncontrolled energy discharge and high current spikes that would otherwise cause semiconductor desaturation.
2Reliability
If the semiconductor switching element is overdimensioned to prevent desaturation during faults, then the reliability is improved, but the device complexity and costs increase
Solution Approach 1:
The patent employs a safety fuse as a disposable protective element that is designed to fail safely under fault conditions. Instead of relying on the semiconductor switching element to handle all fault conditions (which would require overdimensioning), the fuse provides inexpensive, simple fault isolation, reducing the requirements for the semiconductor component.
3Ease of operation
If a unidirectional switching module with parallel diode is used, then the current management and selective tripping are improved, but the device complexity increases due to additional components
Solution Approach 1:
The patent designs the switching module where the parallel diode serves multiple functions: it enables bidirectional current flow capability, provides a controlled path during switching transitions, and assists in fault isolation. This multi-functionality reduces the need for additional dedicated components, offsetting the complexity increase with functional consolidation.
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 selective tripping of switching devices, reduces the need for overdimensioning, and enhances system robustness and cost-effectiveness by managing currents and energy discharge effectively during faults, while maintaining low power losses.
Implementation Method 1
a diode, which is in the conducting state in the opposite current direction
Data Source
AI summary
A circuit breaker device is for coupling a DC voltage branch to a positive and a negative conductor on a DC voltage bus. In an embodiment, the circuit breaker device includes a series circuit including a safety fuse and a unidirectional switch module. The switch module has a parallel circuit includes a controllable semiconductor switch element that is conductive in a first current direction and a diode that is conductive in the opposite current direction.