I have a couple of questions regarding the use of Gallium Nitride MOSFET devices in a DC/DC converter design of mine. My topology is an LCC full bridge converter.
My knowledge is not at expert level so if anything I say is incorrect, please correct me. Typically in these converters, with Silicon devices, the body diode of the device acts as a freewheeling diode to resonant current when the switches are off. However, in Gallium MOSFETs, there is NO body diode.
Furthermore, typically to remove turn-off losses, capacitor/resistor lossy snubbers are connected in parallel to slow down the dv/dt of the switch and to avoid hard-switching at turn-off. However, since Gallium Nitride devices have no reverse recovery current - will the lossy snubbers be needed?
My questions are twofold:
How do Gallium Nitride devices commutate current when they are switched off? Will an external diode need to be included to provide a current path in this situation?
Is there any point using snubber networks across full bridge resonant circuits that include Galium devices if there is no reverse recovery charge? Or are they lossless under switch off anyway? Is there any point soft-switching GaN devices at all?