DC Switching Device with Dual Mechanical Switches for Low Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing direct-current switching devices for kiloampere ranges require all three switches to be actuated for shutdown, leading to inefficient switching behavior and higher electrical losses due to the use of semiconductor switches, which have non-negligible power losses.
Innovation Solution
A direct-current switching device with two mechanical switches in series, where one switch is designed for fast fault current switching and the other for stable normal operation, utilizing a semiconductor power switch in parallel, and a control device to manage switching based on operational commands and fault conditions, allowing only two switches to be actuated for shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a semiconductor power switch is used in the DC switching device, then the switching speed and control precision are improved, but the electrical losses increase due to the non-negligible forward voltage drop across the semiconductor switch
Solution Approach 1:
The DC switching device is segmented into multiple switches (first mechanical switch, second mechanical switch, and semiconductor power switch) with distinct functions. The mechanical switches handle normal operation switching with minimal losses, while the semiconductor switch provides fast switching capability for fault conditions. This segmentation allows the system to optimize for both low losses and fast switching by using the appropriate switch type for each operating condition.
2Reliability
If all three switches (first mechanical switch, second mechanical switch, semiconductor power switch) are actuated for shutdown, then the switching reliability is improved, but the switching complexity and operational inefficiency increase
Solution Approach 1:
The control strategy dynamically adapts the switching sequence based on the operating condition. For normal operation shutdown, only the first mechanical switch and semiconductor power switch are actuated. For fault conditions, the second mechanical switch and semiconductor power switch are actuated instead. This dynamic control approach reduces the number of switches that need to be actuated while maintaining reliability through conditional switch selection.
Solution Approach 2:
Each switch in the system is designed with specific local qualities optimized for its intended function. The first mechanical switch is optimized for normal operation switching, the second mechanical switch for fault condition switching, and the semiconductor power switch for fast controlled switching. This specialization allows each component to excel at its specific task, improving overall system reliability while simplifying control logic.
3Speed
If the second mechanical switch is designed for fast switching to handle fault currents, then the fault current switching speed is improved, but the number of reliable switching operations decreases due to increased wear and tear
Solution Approach 1:
The switching functions are segmented between different switch types. Mechanical switches handle normal operation switching where speed is less critical, allowing them to operate within their durability limits. The semiconductor power switch handles fast switching requirements for fault conditions, where its solid-state nature provides both speed and unlimited switching cycles without mechanical wear. This segmentation resolves the contradiction by matching each switch type to its optimal application.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates, amongst other things, to a DC switching device (10) for switching direct currents (I), in particular direct currents in the kiloampere range, having an electrical series circuit (R) which comprises a first and a second switch (20, 30), wherein the first switch (20) is a mechanical switch and has a moving contact system for switching purposes, and having a semiconductor power switch (40) which is connected in parallel with the series circuit (R). According to the invention, provision is made for the second switch (30) of the series circuit (R) to likewise be a mechanical switch and to likewise have a moving contact system for switching purposes, and for the moving contact system of the second switch (30) to be designed in such a way that it can switch more rapidly than the moving contact system of the first switch (20).