Thyristor Fault-Current Triggering to Prevent Thermal Destruction
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Solution Overview
Problem
Thyristors in high voltage, high current applications are prone to thermal destruction due to fault currents, as their blocking ability deteriorates with rising junction temperature, leading to a high resistance electrical path and potential failure.
Innovation Solution
A thyristor circuit with a thyristor control circuit and current detector that selectively triggers the thyristor into a conductive state when a fault current exceeds a predetermined threshold, preventing further temperature rise and potential destruction by maintaining the conductive state until a circuit breaker can interrupt the current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thyristor remains in blocking state during fault current condition, then the fault current is blocked, but the junction temperature rises and blocking ability deteriorates leading to thermal destruction
Solution Approach 1:
Instead of keeping the thyristor in blocking state to prevent fault current, the invention inverts the approach by deliberately triggering the thyristor into conductive state during fault conditions. This allows the fault current to pass through the thyristor with low resistance, preventing junction temperature rise and thermal destruction, while the circuit breaker subsequently interrupts the fault current at the circuit level.
2Reliability
If additional components like series reactors are added to protect thyristors, then thermal destruction is prevented, but device complexity increases
Solution Approach 1:
The invention makes the thyristor itself serve the protective function by utilizing its own conductive state to withstand fault currents. The thyristor's inherent ability to conduct current is repurposed as a protection mechanism, eliminating the need for external protective components like series reactors. The control circuit simply needs to detect fault conditions and trigger the thyristor accordingly.
Data Source
AI summary
A thyristor circuit includes at least one branch including at least one thyristor, a thyristor control circuit and a current detector. The current detector is configured to detect a current value representative of an electrical current flowing through the thyristor and to input the detected current value into the thyristor control circuit. The thyristor control circuit is configured to determine a fault condition in which the detected current value exceeds a predetermined current threshold based on a deteriorated blocking ability of the thyristor. Dependent on the determination result, the thyristor control circuit triggers the thyristor into a conductive state.