Loss Separation in Hard- and Soft-Switching GaN HEMTs operated in a 10 kW Isolated DC/DC Converter

In this paper, GaN power transistors are operated in a 10 kW isolated DC/DC converter, investigating their loss distribution. Based on a combination of calorimetric loss-, and clamped drain source voltage measurements, the losses are separated in conduction and switching losses. Furthermore, the influence of dynamic Ron effects is identified during continuous operation. The chosen ZCZVS topology allows for comparison of hard- and soft-switching operation of the GaN devices. The loss separation reveals almost twice of additional dynamic Ron losses in the hard switching leg. In this case, the dynamic losses account for about one third of the conduction losses.