H5-HERIC based transformerless multilevel inverter for single-phase grid connected PV systems

Transformerless photovoltaic systems are one of the best options to connect a photovoltaic system to the electrical grid given their high efficiency, low cost, small size and low weight regarding their counterparts based on a transformer. In this paper a multilevel single-phase inverter is aimed to link a photovoltaic generator with the electrical grid with reduced common mode current. A sinusoidal based modulation strategy is also presented which focus not only in the reduction of the common mode current but also in the reduction of the switching and conduction losses. Five voltage levels are obtained at the inverter output, therefore, a good behavior is achieved regarding harmonic distortion. Numerical results show that the proposed inverter and modulation strategy give a reduced common mode current and low harmonic distortion which is suitable for transformerless photovoltaic systems.