Catastrophic Failure Prediction for Phase Control Thyristors in AC Pulsed Power Applications

This paper presents a theoretical study useful for the estimate of ride through capability of phase control thyristors submitted to high single- and multi-cycle AC current surges. The development of a calculation technique is presented, which is based exclusively on data sheet parameters. It allows for the previous determination of the usefulness of a given phase control thyristor to any application in which a high amplitude, short duration current waveform is to be handled. Furthermore, an alternative, simple method for the calculation of instantaneous virtual junction temperature of the device is presented. It is compared to the traditional equivalent power pulse technique. The results are experimentally verified by the direct application of pre-stablished current waveforms to a commercially available model of thyristor.