Rectifier Shorting Device Thyristor Ring Arc Fault Protection
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Solution Overview
Problem
High power rectifiers face challenges in efficiently mitigating arc faults, as existing methods are either too slow or costly to prevent damage, and may not protect against internal arc faults within the rectifier circuitry.
Innovation Solution
A high power rectifier system with a shorting device using thyristors that delta-connects input phases and includes an arc detection system to quickly short-circuit both input and output phases, preventing damage by extinguishing arcs within 4 milliseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional arc fault breakers are used to open-circuit the rectifier upon detecting an arc fault, then the external circuit is disconnected from the rectifier, but the method is too slow to prevent damage and cannot protect against internal arc faults within the rectifier circuitry
Solution Approach 1:
The shorting device is pre-configured with thyristors connected in a ring topology between input phases and to output phases, ready to immediately short-circuit upon detection of an arc fault. This preliminary arrangement eliminates the need for complex switching operations during the fault event, enabling response within 4 milliseconds.
Solution Approach 2:
Instead of attempting to interrupt the arc fault current (which would require slow-breaking switches and generate dangerous voltage spikes), the invention converts the harmful arc fault into a beneficial short-circuit condition. By deliberately creating a controlled short-circuit path through the thyristor ring, the arc is extinguished rapidly as the short-circuit current suppresses the arc formation, protecting the rectifier components.
2Reliability
If arc fault breakers are used to disconnect the external circuit, then protection is provided, but the cost of building outdoor container or housing to withstand arc fault explosion is too high
Solution Approach 1:
The invention converts the potentially explosive arc fault into a controlled short-circuit event that dissipates energy safely. By rapidly shorting the phases involved in the arc fault, the system prevents the arc from developing into an explosive condition, eliminating the need for expensive explosion-proof housings or outdoor containers.
Solution Approach 2:
The shorting device uses relatively simple thyristor components that can be replaced if needed, rather than requiring expensive protective infrastructure. The focus is on using affordable electronic switching components to achieve protection, rather than investing in costly physical barriers.
3Reliability
If the rectifier uses existing shorting methods with antiparallel semiconductor switches, then arc mitigation is achieved, but the device complexity increases and may not provide sufficient protection speed
Solution Approach 1:
The thyristors are pre-connected in a ring topology between the input phases and to the output phases, with all thyristors oriented in the same direction. This preliminary configuration allows any phase to be shorted to any other phase by activating the appropriate thyristors in the ring, providing comprehensive protection without requiring complex switching logic or additional components.
Solution Approach 2:
The ring-connected thyristor structure provides universal shorting capability between all phases. The same ring structure can short any combination of phases (input-to-input, input-to-output, output-to-output) depending on which thyristors are activated, making the device highly versatile without increasing complexity.
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 effectively prevents damage to rectifier components and enclosures by rapidly short-circuiting phases upon arc detection, allowing for efficient arc fault mitigation and reducing the cost of rectifier maintenance by enabling easy replacement of the shorting device.
Implementation Method 1
The shorting device comprises thyristors for conducting a shorting current
Implementation Method 2
an arc detection device for detecting an electric arc fault of the rectifier
Data Source
Figure 1
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AI summary
A rectifier (14) for converting an AC current into a DC current comprises at least two half-bridges (22) comprising semiconductor switches (32), which are connected in parallel with respect to two output phases (18a, 18b) of a DC output (18) of the rectifier (14), wherein each half-bridge (22) is adapted for rectifying an input phase (16a, 16b, 16c) of an AC input (16) of the rectifier (14), an arc detection device (26) for detecting an electric arc fault of the rectifier (14); a shorting device (28) for shorting the input phases (16a, 16b, 16c), when actuated by the arc detection device (26); wherein the shorting device (28) comprises thyristors (34) for conducting a shorting current, which thyristors (34) delta-connect the input phases (16a, 16b, 16c); wherein the thyristors (34) of the shorting device (28), which interconnect the input phases (16a, 16b, 16c), are connected in a ring to the input phases (16a, 16b, 16c), in which ring the thyristors (34) all have the same orientation.