A Single-Phase Asymmetrical T-Type Five-Level Transformerless PV Inverter

This paper presents a transformerless single-phase inverter topology based on a modified H-bridge-based multilevel converter. The topology comprises two legs, namely, a usual two-level leg and a T-type leg. The latter is based on a usual two-level leg, which has been modified to gain access to the midpoint of the split dc-link by means of a bidirectional switch. The topology is referred as an asymmetrical T-type five-level (5L-T-AHB) inverter. An ad hoc modulation strategy based on sinusoidal pulsewidth modulation is also presented to control the 5L-T-AHB inverter, where the two-level leg is commuted at fundamental frequency. Numerical and experimental results show that the proposed 5L-T-AHB inverter achieves high efficiency, exhibits reduced leakage currents, and complies with the transformerless norms and regulations, which makes it suitable for the transformerless PV inverters market. 11 This updated version includes experimental evidence, considerations for practical implementation, efficiency studies, visualization of semiconductor losses distribution, a deeper and corrected common mode analysis, and an improved notation among other modifications.