A study of the internal device dynamics of punch-through and nonpunch-through IGBTs under zero-current switching

The effective use of power insulated gate bipolar transistors (IGBTs) requires a good understanding of their internal device physics. This understanding is essential for the optimal interaction among the IGBTs, their snubber elements and the power circuit in which the IGBTs operate. As switching frequencies are pushed to higher values, switching loss reduction becomes an essential part of the design and optimization process. Soft switching techniques such as zero-voltage switching (ZVS) and zero-current switching (ZCS) are widely used for this purpose. This study provides an insight into the internal dynamic behavior of IGBTs under zero-current switching. The latter is accomplished through mixed-mode simulation, providing the necessary insight for the improvement of circuit and device performance. In particular, the authors have analyzed the behavior of the negative current in nonpunch-through (NPT) devices after the first zero-current crossing and the effect of the turn-off delay on the tail current. They have also experimentally characterized punch-through (PT) and NPT IGBTs to confirm the insights provided by the mixed-mode simulation.