An Interleaved Single-Stage Switched-Boost Common-Ground Multilevel Inverter: Design, Control, and Experimental Validation

Multilevel inverters (MLIs) with a common-ground (CG) circuit design and a switched-boost (SB) technique are of interest in transformerless grid-connected applications due to the enhanced overall efficiency, higher power density and reduced leakage current concern. Utilization of the SB technique in MLIs leads to obtaining a single-stage power conversion platform with a dynamic voltage boosting feature. Drawing a continuous input current and spike-free current stress of the devices are two additional features of SB-based MLIs. Regarding the current state-of-the-art contributions, an interleaved CGSB-based MLI is introduced in this work. The main benefits of the proposed topology are larger injected grid current handling capability with a reduced current stress, uniform peak voltage stress across the devices, bidirectional power flow operation, controllable power sharing, and generalization capability to realize any number of output voltage levels. Through a modular design with a phase-shifted PWM technique, the injected grid current is shared among the modules, while the size of the grid-interface filters is reduced, leading to establishing a practical design with enhanced overall efficiency. The working principle of the proposed converter is discussed in detail. Design guidance, comparative study and extensive closed-loop experimental results obtained from a 5.1 kW grid-tied laboratory-built prototype are then given to validate the feasibility and performance of the proposed solution.