Thyristor Gate Voltage Detection in Parallel Triggering Circuits
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Solution Overview
Problem
Detecting proper triggering of thyristors connected in parallel is challenging due to voltage breakdown across all parallel-connected thyristors, and existing methods like temperature sensors provide delayed feedback, while current sensors increase costs and circuit complexity.
Innovation Solution
Implementing gate drive units with voltage sensors and configurable integrated circuits to measure gate voltage after gate pulses, using a delay or filter to stabilize the voltage, and comparing it against a threshold to determine thyristor triggering, with further pulses applied if necessary to ensure proper triggering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are used to monitor parallel-connected thyristors, then detection capability is provided, but feedback is delayed due to thermal constraints
Solution Approach 1:
The patent replaces temperature-based monitoring (thermal field) with voltage-based monitoring (electrical field). By measuring the voltage across each thyristor, the system achieves instantaneous detection of triggering status without the thermal inertia delay inherent in temperature sensors. This substitution of measurement principle resolves the contradiction between detection reliability and feedback speed.
2Reliability
If current sensors are used to detect current flow through each thyristor, then triggering detection is achieved, but costs and circuit complexity increase
Solution Approach 1:
The patent extracts the detection function from complex current sensing circuits and implements it through simple voltage measurement across each thyristor. By measuring the voltage drop across the thyristor terminals, the system determines triggering status without requiring current sensors or complex circuitry. This extraction of the essential detection function resolves the contradiction between reliability and device complexity.
3Difficulty of detecting and measuring
If voltage breakdown monitoring is used for parallel-connected thyristors, then detection is possible, but it is not suitable due to voltage breakdown occurring across all parallel-connected thyristors when the first is turned on
Solution Approach 1:
The patent applies local quality by measuring the voltage across each individual thyristor rather than monitoring the common voltage breakdown point. This localized measurement allows detection of each thyristor's triggering status independently, even in parallel configurations. The small voltage drop across the gate-cathode junction of each thyristor provides a unique local signature that distinguishes triggered from non-triggered devices, resolving the detection difficulty while maintaining reliability.
Data Source
AI summary
Provided is an electric circuit that may be part of a power converter and which includes a plurality of electrically connected thyristors. Each thyristor has a gate terminal electrically connected to a gate drive unit adapted to generate gate pulses for triggering the thyristor. At least one of the plurality of gate drive units is adapted to measure the gate voltage of the respective thyristor after one or more gate pulses have been applied to the respective thyristor. The measured gate voltage may be used to determine if a thyristor has not been triggered by the gate pulse(s) e.g., if the gate voltage is below a voltage threshold.