Sliding-mode control design of parallel-connected switching converters for modular transformerless DC-AC step-up conversion

This paper presents the design of a sliding-mode control of parallel-connected Boost-Buck inverter modules for a modular transformerless DC-AC step-up conversion. Two sets of sliding control laws are proposed. The first one is based on the Master-Slave strategy to control the Buck stages for a DC-AC conversion, ensuring at the same time an output voltage regulation and a proper current sharing among the inverter modules. The second set is devoted to the control of the Boost stages in order to perform a step-up DC-DC conversion ensuring simultaneously the Buck stages proper operation by preserving their sliding domains. Experimental results carried out on two parallel-connected Boost-Buck inverter modules are presented to validate the proposed design.