DC Voltage Switch Using Transformer Counter-Voltage for Arc Extinction
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Solution Overview
Problem
Switching off direct current (DC) is more challenging than alternating current (AC) due to the persistence of arcs when contacts open, leading to potential switch destruction, and existing solutions either require semiconductor switches or inefficient energy management.
Innovation Solution
A DC voltage switch arrangement featuring a converter and a transformer with a mechanical switch, where a counter-voltage is generated using an intermediate circuit capacitor and a transformer, allowing for quick current zero crossing and arc extinction without semiconductor switches, enabling bidirectional switching and minimizing electrical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical switch is used to switch off DC current, then the device complexity is reduced and electrical losses are minimized, but the arc extinction becomes difficult and the switch reliability deteriorates
Solution Approach 1:
A transformer is introduced as an intermediary device between the mechanical switch and the DC current path. The transformer converts DC current switching into AC voltage generation, where the mechanical switch controls the transformer's primary winding rather than directly interrupting DC current. This mediator enables reliable switching without requiring the mechanical switch to directly handle high-current DC interruption.
Solution Approach 2:
The patent replaces the mechanical DC current interruption system with an electromagnetic system. Instead of using a mechanical switch to directly open DC current contacts, the system uses a mechanical switch to control a transformer, which then generates AC voltage to achieve current zero-crossing. This substitution transforms a mechanical arc-extinguishing problem into an electromagnetic control problem.
2Speed
If semiconductor switches are used to achieve fast switching and arc extinction, then the switching speed is improved, but the electrical losses increase and device complexity increases
Solution Approach 1:
The patent employs a mechanical switch with relatively slow switching characteristics (compared to semiconductor switches) but optimizes the overall system through the transformer's AC generation capability. The mechanical switch, while not as fast as semiconductor switches, achieves sufficient switching performance when combined with the transformer's ability to create rapid current zero-crossing through AC voltage generation, thereby avoiding the energy losses associated with semiconductor switches.
3Reliability
If the transformer's primary winding inductance is high, then the galvanic isolation and voltage transformation are improved, but the current zero crossing time increases and switching speed deteriorates
Solution Approach 1:
The patent optimizes the transformer's primary winding inductance parameter to achieve a balance between galvanic isolation and switching speed. By carefully selecting the inductance value, the system ensures sufficient galvanic isolation for safety and voltage transformation while maintaining a compact time constant that enables rapid current zero-crossing. This parameter optimization allows the mechanical switch to open within the short time period required for arc suppression.
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 achieves rapid arc extinction and efficient switching with reduced electrical losses, allowing for reliable DC current switching while reusing existing resources and minimizing component count.
Implementation Method 1
a transformer (14) having a primary-side winding (141) in the operating current path and a secondary winding (142) connected to a voltage source (161), wherein the voltage source (161) generates a counter-voltage to the voltage in the operating current path through the transformer (14)
Implementation Method 2
the voltage source is an intermediate circuit capacitor of a converter which, for example, is otherwise related to the DC voltage network
Data Source
Figure 1~2
Figure 3~4
AI summary
Disclosed is a DC voltage switch comprising two terminals between which an operating current path extends that includes a mechanical switch, and comprising means for generating a reverse voltage in relation to the voltage in the operating path; said means include a transformer, the primary side of which is connected in series to the mechanical switch in the operating current path, a voltage source that is connected to the secondary side of the transformer, and a switch that is connected in series to the voltage source.