Unified Sliding-Mode Control of Non-Inverting Buck-Boost Converters

Non-inverting buck-boost (NIBB) converters used as dc-dc optimizers in photovoltaic (PV) applications are required to operate over a very wide range of conversion ratios and power levels. Conventional control approaches typically include complex mode switching and compensators designed for different modes of operation, which often lead to disturbances and even potential instabilities across mode transitions. This paper proposes a unified sliding mode control approach in order to achieve smooth mode transitions, while at the same time ensuring excellent dynamic performance over a wide operating range. The proposed approach is verified in simulation as well as experimentally on a 20V-to-60V input, 40V output NIBB case study.