Seven-level cascaded ANPC-based multilevel converter

A seven-level converter based on the cascaded connection of a three-level active neutral-point-clamped (ANPC) converter and individual H-bridge cells per phase is presented in this paper. This converter only requires a single DC source for all three phases and extends the amplitude of output voltage of the converter with similar DC-link voltage. The operation principles and control strategies based on a fundamental frequency harmonic elimination PWM are discussed. The regulation of FC voltage depends on the positions of switching angles over a quarter period in the available solutions and on the load power factor. In order to extend the regulation of the FC voltage into higher modulation indices an additional switching in the top voltage level is also considered. Experimental results taken from a low-power single-phase laboratory setup that verify the theoretical considerations and simulation results are presented.