A Common Ground Switched-Capacitor Multilevel Inverter Using Capacitors of Small Value and Featuring a Continuous Input Current

A new input source - load common ground switched-capacitor multilevel inverter (CG - SCMLI) with superior features is proposed. The first goal is to assure a continuous input current despite the creation of the common ground that, in the available solutions, prevented the input source of supplying energy when synthesizing the negative levels of the staircase output voltage, creating thus discontinuities in the input current. The availability of a common ground and of a low pulsating input current are the two qualities provided by the new inverter which fit exactly the requirements of the photovoltaics cells used to power the energy grid. A charge pump cell is used for assuring the new feature of the input current, but also for allowing a design with much smaller capacitors, that is the second goal of this research. Even if the proposed inverter contains more switches than the available CG-SCMLIs, the above qualities gives the superiority of the new solution. A prototype of 200 W supplied by an array of solar cells of MPPT voltage 120V is implemented in the laboratory. It uses capacitors of 32.9 µF, which gives a high power density to the prototype. The new 7 - levels inverter supplies a voltage of 220 Vrms to a standalone consumer. The measured efficiency is 97.4%.