Adaptive dead time in high frequency GaN-Inverters with LC output filter

Abstract

GaN-HEMTs offer new possibilities for the development of advanced power electronics. Due to lower parasitics, GaN devices enable higher switching frequencies and thus higher power densities. However, in comparison to silicon MOSFETs the higher voltage drop during reverse conduction causes more losses during dead time. Therefore, it is essential to adjust the dead time to the actual operation point. This paper proposes a novel method to determine the optimal dead times of the transitions within the half-bridges of an inverter with LC output filter. The dead time is adapted in every switching cycle using variables, which are typically present in the control unit of the inverter. This allows an efficient implementation of the method on microprocessors. The study reveals, based on a 48 V GaN inverter, that the optimal dead time varies in a large range and thus indicates the necessity of an adaptive dead time.