A Novel Method for Identifying the Reverse Recovery State of Thyristors Based on Gate Voltage

As a critical power electronic device in dc transmission systems, thyristors are highly favored for their low conduction loss, excellent surge capability, economic efficiency, and reliable current-carrying performance. However, in key applications such as commutation converters, active inverters, and circuit breakers, accurately determining the off-state of thyristors remains a significant challenge for the reliable operation of these systems. The traditional method relies on detecting the reverse recovery current flowing through the thyristor to determine its off-state. This method is often plagued by detection difficulties, high costs, and insufficient accuracy, and no new methods for detecting the off-state of thyristors have been proposed for decades. To address the difficulty in recognizing the off-state of thyristors, this article proposes a novel method for identifying the reverse recovery state of thyristors based on the gate voltage of the thyristor. This method eliminates the need to measure the high current on the primary side, requiring only the measurement of a small voltage on the secondary side to accurately determine the thyristor's reverse recovery state. Experimental validation confirms the feasibility of this approach. The proposed method offers advantages such as low cost and ease of integration, providing an effective solution for identifying the reverse recovery state of thyristors in existing equipment.