Hybrid DC Switching Apparatus with Segmented Branches
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hybrid switching apparatuses for DC electric grids face challenges in managing short-circuit currents effectively, as they require long commutation times and are bulky and expensive due to the need for high current endurance, and they often suffer from reliability issues and high maintenance costs due to long arc durations at high voltages.
Innovation Solution
A hybrid switching apparatus comprising an electromechanical branch and a solid-state branch connected in parallel, with a current blocking and limiting circuit, where the electromechanical device self-acts to switch upon current thresholds without external control, and the solid-state devices are used to manage currents after commutation, allowing for faster intervention and reduced size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromechanical switching devices are used, then galvanic isolation and low cost are achieved, but interruption rating and arc duration are insufficient
Solution Approach 1:
The switching device is divided into two independent branches: an electromechanical branch for galvanic isolation and a solid-state branch for fast current interruption. Each branch operates autonomously to address different aspects of the contradiction, with the electromechanical branch providing reliable isolation and the solid-state branch providing rapid arcless switching.
Solution Approach 2:
The patent combines electromechanical switching devices and solid-state switching devices into a single hybrid apparatus. The electromechanical branch handles galvanic isolation requirements while the solid-state branch handles fast interruption requirements, merging the advantages of both technologies to resolve the contradiction between reliability and arc duration.
2Speed
If solid-state switching devices are used, then arc-less switching and fast operation are achieved, but cooling requirements and device size increase
Solution Approach 1:
The solid-state branch is designed to operate only during fault conditions for current interruption, rather than handling continuous power transmission. This partial action reduces the thermal load and cooling requirements, as the solid-state devices are activated only when fast switching is needed, not during normal continuous operation.
3Reliability
If hybrid switching apparatus is used, then interruption rating is improved, but current commutation time increases
Solution Approach 1:
The solid-state switching devices are pre-configured in the second branch and ready to immediately assume current flow when the electromechanical devices open. The parallel configuration allows instantaneous current transfer without commutation delay, as the solid-state branch is already in position to conduct current the moment the electromechanical branch opens.
4Reliability
If solid-state devices are designed for high current endurance, then reliability is improved, but device size and manufacturing cost increase
Solution Approach 1:
The current handling duty is segmented between two branches: the electromechanical branch handles normal continuous current flow, while the solid-state branch handles only fault current interruption. This segmentation allows the solid-state devices to be designed for short-duration high-current withstanding capability rather than continuous high-current endurance, reducing size and cost.
Data Source
AI summary
A switching apparatus includes first and second electric terminals, and first and second electric branches comprising one or more switching devices. The second electric branch is electrically connected in parallel with said first electric branch between said first and second electric terminals. The switching apparatus comprises a current blocking circuit adapted to block a current along said second branch. The current blocking circuit includes a first switching device of solid-state type and a first electronic circuit electrically connected in parallel to said first switching device of solid-state type. The switching apparatus further comprises a current limiting circuit adapted to limit a current flowing along said second electric branch. Said current limiting circuit is electrically connected in series with said current blocking circuit and it includes a second switching device of solid-state type and a second electronic circuit electrically connected in parallel to said second switching device of solid-state type.