A Novel Single-Phase Five-Level Transformerless H9 Inverter with Voltage Boosting Capability

In this paper, a new 5-level inverter topology with nine switching devices is presented which is capable of connecting the roof top PV systems to the single-phase grid without requiring a line frequency transformer. The leakage current issue followed by the transformer elimination is taken care by achieving a constant Total Common Mode Voltage (TCMV). A detailed TCMV analysis is presented considering the parasitic capacitance of the switching devices. The multilevel performance of the proposed H9 inverter reduces the harmonic distortion in the output voltage. The additional features of the H9 inverter includes reactive power supplying capability and voltage boosting capability. A switched capacitor network is used to add the voltage boosting capability to the proposed H9 topology. Theoretically, the maximum output voltage that can be achieved is twice of the input dc bus voltage. To validate the mentioned features of H9, simulation studies are performed and the results are presented.