GaN Power Semiconductors for PV Inverter Applications - Opportunities and Risks

Upcoming transistors made from gallium nitride (GaN), just as silicon carbide (SiC) are promising better efficiency or rather a higher degree of integration by using much higher switching frequencies as well as smaller and lighter filters, cooling effort and housings. Less system size and lowered overall costs for power electronic applications like photovoltaic (PV) inverters become possible. These advantages as well as the risks and additional requirements of GaN in comparison to state-of-the-art silicon (Si) have been analyzed during the German Federal Ministry of Education and Research (BMBF) founded project "NeuLand". The determined 600V GaN High Electron Mobility Transistors (HEMTs) were fabricated by MicroGaN and packed by Infineon. Both partners contributed parts to this paper. At SMA a 1.2kW, 200kHz boost converter in a PV-oriented set-up has been developed reaching a peak efficiency of 99.2% using a tremendously shrunken choke. The results measured with various GaN devices are presented within this paper together with miscellaneous challenges, open questions and the benchmark of current Si and SiC devices, allocated by Infineon.