A five-level diode clamped inverter with self-stabilization of the DC-link voltage for grid connection of distributed generators

In this paper, a new control system for single phase five-level diode clamped inverters (DCI) is presented. The obtained modeling shows that high voltage multilevels are obtained by combination of four different three-level functions, which are called conversion functions. Therefore a novel PWM strategy is designed by a particular modulation for creating four fictive modulated voltage systems via the direct width modulation and the position setting of both conversion functions. Redundancies of different switch configurations for the generation of intermediate voltages are used to limit the deviations of capacitor voltages. A correct filtered AC output is obtained with a classical closed loop control. Experimental and simulation results for a three-level and five-level diode clamped inverter are presented to demonstrate the validity of the proposed balancing modulation.