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.