High-Current Pulse Switching by Thyristors Triggered in the Impact-Ionization Wave Mode

摘要

The operation of a thyristor switch triggered in the impact-ionization wave mode was investigated. The switch contained two series-connected T253-800-24 thyristors of the tablet design with a semiconductor-structure diameter of 56 mm. When a triggering pulse is applied to the switch at a voltage rise rate dU/dt of more than 1 kV/ns, the transition time of the thyristors to the conducting state was shorter than 1 ns. It was shown that the maximum amplitude of the no-failure current increases with an increase in dU/dt at the triggering stage. The possible mechanism of the influence of the dU/dt value on the thyristor breakdown current is discussed. In the safe operating mode at dU/dt = 6 kV/ns (3 kV/ns per single thyristor), the switch discharged a storage capacitor with a capacitance of 1 mF, which was charged to a voltage of 5 kV, through a resistive load of 18 m Omega. The following results were obtained: the discharge-current amplitude was 200 kA, the initial current rise rate was 58 kA/mu s, the pulse duration (FWHM) was 25 mu s, and the switching efficiency of 0.97.