Shoot-Through Protection for an IGCT-Based ZVS Resonant DC Transformer

IGCTs have successfully demonstrated to be well-suited devices for an application in medium-voltage dc transformers based on LLC resonant converter topology. This application enables unusually high switching frequencies in kHz range thanks to the zero-voltage switching while maintaining the high conversion efficiency. Moreover, the clamp circuit that is an inseparable part of every hard-switched IGCT-based converter can be completely omitted -- further lowering the converter complexity and cost. Nevertheless, without the clamp circuit, the effect of shoot-through becomes fatal, considering that the IGCTs have a defined mode of failure in short-circuit and the desaturation effect, is practically non-existent. To prevent the shoot-through, this letter proposes a simple, yet effective, protection method based on anode-voltage measurement that can be implemented locally on the IGCT gate unit. The validity of the solution is demonstrated using a custom IGCT gate unit in a medium-voltage resonant test setup.