This paper presents a buck-boost converter which is modified to utilize new 600 V gallium nitride
(GaN) power semiconductor devices in an application requiring 1200 V devices. The presented
buck-boost converter is used as a part of a dc/dc stage in an all-GaN photovoltaic (PV) inverter
and it provides a negative voltage for the 3-level neutral-point-clamped (NPC) PWM inverter
which is connected to the utility grid. Since in this application the transistor and the diode
of the buck-boost converter need to block the sum of the PV string voltage (which is normally
in the range from 150 to 350 V) and the dc bus voltage (which is in the order of 400 V), the
1200 V devices or series connection of 600 V devices need to be employed. Currently, 1200 V
GaN power semiconductor devices are not commercially available. Therefore, the standard buck-boost
converter is modified to enable the use of 600 V GaN devices in this particular application.
Based on the proposed converter topology, a PSpice simulation model and a 600 W converter prototype
were developed. Both simulation and experimental results show successful operation of the converter