The advantages of neutral-point clamped single-phase single-stage transformer-less inverters based on dual-mode time-sharing technology are evident in terms of high efficiency, low voltage stress, Boost and Buck operation, and leakage current suppression. In this paper, a novel single-stage transformer-less Buck and Boost Inverter (SS-TL-BBI) based on neutral-point clamped structure, dual-mode time-sharing technology, and full MOSFET switches is proposed, in which a single freewheeling diode is shared between the two Buck circuits of the positive half-cycle and the negative half-cycle of the grid. Besides, this paper also describes the topology structure, Buck and Boost operating modes composed of eight switching states, mathematical modeling, control method, design guidelines, leakage current suppression principle, and comparison with other schemes. Finally, A 500 W prototype applied to a grid voltage of 110 VRMS and 50 Hz is fabricated to validate the theoretical analysis and performance tests, and a peak efficiency of 97.98% is measured.
Xu et al. (Thu,) studied this question.