Performance of 500 A, 450 V parallel MOS-controlled thyristors (MCTs) in a resonant DC-link circuit

The performance of twelve parallel MOS-controlled thyristors (MCTs) in a resonant DC-link circuit is described. Each individual MCT device, with an active area of 0.4 cm/sup 2/, is rated at 80 A and 600 volts. Four MCTs were paralleled to form a switch for a resonant inverter circuit. The criteria for good static and dynamic current sharing are identified to be forward voltage drop and the turn-on voltage characteristic of the MCTs. The current rating of the MCT module was derated from 320 A (at discrete device level) to 200 A. Paralleling of three MCT modules leads to further degradation in current rating to 450 A. The nonuniform distribution of stray inductance present in the MCT switch and circuit is the major cause for the derating of MCTs at switch level. MCTs with various designs were fabricated and analyzed. An optimal design for low turn-on voltage and high current turn-off capability is identified.<
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