Resonant IGCT Soft-Switching: Zero-Voltage Switching or Zero-Current Switching?

In the last thirty years, the integrated gate-commutated thyristor (IGCT) has been employed in medium voltage \,\mathrm{M}\mathrm{W} power level converters and has demonstrated some of the lowest conduction losses of any actively controlled device in traditional hard-switched, sub-\,\mathrm{k}\mathrm{Hz} applications. Extending the use of the device to medium frequency applications, such as dc transformers is possible through soft-switched operation, where low turn- off current and zero-voltage turn- on significantly reduce switching losses. For this purpose, this article explores the tradeoffs in the transition between zero-voltage and zero-current switching conditions of reverse conducting IGCTs. Switching conditions resulting in minimal switching loss are identified for standard commercial devices and engineering samples subjected to increased electron irradiation to reduce switching energy at the expense of on-state voltage. The operation of the IGCTs at the record frequency of 5 \mathrm{k}\mathrm{Hz} is thermally validated under load in the identified switching conditions.