Switching a eMode GaN HEMT under conditions of an inverter module for electrical vehicles (EV)

In this paper the switching behavior of a eMode GaN device under conditions of a power module for electrical vehicles will be presented. During turn-off of the passive switch parasitic turn-on (PTO) can occur. The PTO will lead to higher losses especially in the low load dominated WLTP cycle. An advanced version of a Miller clamping circuit to prevent PTO will be shown. This circuit will reduce the losses significantly. A version with loss optimized PTO, higher gate resistance and with Miller circuit will be compared. The switching speed with Miller clamping is limited by the overvoltage. The condition with the highest overvoltage will be identified, which is necessary for the selection of the external gate resistor. To prevent PTO a lower drive voltage is also beneficial. However, this leads to a high reverse voltage drop of the GaN due to its reverse conduction characteristics. The losses in the WLTP cycle are high, which will be shown for different drive voltage and turn-on delays.