DC Voltage Switch with Pulse-Current Module for Arc Extinguishing
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Solution Overview
Problem
Current DC voltage network systems lack effective and commercially available solutions for rapidly and reliably switching off short-circuit currents, leading to inefficiencies and increased energy losses during normal operation.
Innovation Solution
A DC voltage switch apparatus with a mechanical switch, pulse-current modules, semiconductor switches, and a pulse-current capacitor, which allows for low-loss operation during normal conditions and rapid interruption of fault currents by generating a current pulse to extinguish electric arcs and prevent energy buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a mechanical switch is used to interrupt current in a DC voltage network, then the switching speed is improved, but energy losses occur during normal operation due to the switch being in the path of the current
Solution Approach 1:
The current path is segmented into two parallel branches: one containing the mechanical switch and another containing the pulse-current module with semiconductor switches. During normal operation, current flows through the mechanical switch with minimal losses. During fault conditions, the pulse-current module is activated to interrupt the current, providing rapid switching capability without compromising normal operation efficiency.
Solution Approach 2:
The pulse-current module acts as an intermediary device that provides rapid current interruption capability during fault conditions. It includes a capacitor that stores energy and semiconductor switches that can rapidly open to generate current zero-crossings, enabling fast fault clearance without affecting normal operational performance.
2Speed
If power semiconductor switches are used to interrupt short-circuit currents, then the switching speed is improved, but the device complexity and cost increase
Solution Approach 1:
The system dynamically switches between two operational modes: normal operation using the simple mechanical switch, and fault interruption using the pulse-current module with semiconductor switches. This dynamic approach allows the system to use complex components only when necessary, reducing overall complexity and cost while maintaining fast switching capability for fault clearance.
Solution Approach 2:
The semiconductor switches in the pulse-current module are activated periodically or on-demand during fault conditions to generate current zero-crossings. They operate in pulsed mode rather than continuously, which reduces their wear and allows the use of simpler semiconductor devices rather than continuously-rated high-power switches.
3Reliability
If arresters are provided to dissipate stored energy during switching, then the reliability is improved, but the loss of energy during normal operation increases
Solution Approach 1:
A capacitor is included in the pulse-current module that is pre-charged during normal operation to store energy. During fault interruption, this pre-stored energy is used to generate current zero-crossings and extinguish arcs, eliminating the need for arresters that would continuously dissipate energy. The preliminary energy storage enables reliable fault clearance without continuous energy losses.
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
Enables reliable and cost-effective switching of fault currents with minimal losses during normal operation, effectively interrupting currents in both directions and dissipating stored energy, thus improving the reliability and efficiency of DC voltage network management.
Implementation Method 1
comprises a pulse-current capacitor (25), which is connected in parallel with the two series of in each case two of the semiconductor switches (21...24)
Implementation Method 2
An electric arc is produced when the mechanical switches are opened. The voltage dropped at the electric arc ignites the power semiconductor switch, as a result of which the parallel opened mechanical switch is short-circuited. The electric arc is extinguished.
Data Source
AI summary
A DC voltage switch may include: a first node and a second node for series integration into a pole of a DC voltage line; a third node for the other pole of the line; a mechanical switch between the first and second nodes; a pulse-current module in parallel with the switch; four semiconductor switches connected as bridges comprising two series of two semiconductor switches; a pulse-current capacitor in parallel with the two series; and a switchable semiconductor element. The pulse-current module includes three module nodes. Potential points between the semiconductor switches of the two series correspond to the first and second module node and the outer ends of the two series of in each case two of the semiconductor switches are connected in pairs to a fourth module node and a fifth module node and the semiconductor element is between the fifth and third module node.