Five-Level Multiple-Pole PWM AC–AC Converters With Reduced Components Count

This paper proposes novel multilevel ac/dc/ac converters with reduced number of semiconductor devices to achieve light weight, efficiency, and better input current quality. The proposed three-phase front-end bidirectional five-level (5L) rectifier and rear-end 5L inverter are constructed based on multiple-pole multilevel diode-clamped (M²DCC) approach, which consist a total number of 24 diode components clamped. Based on the M²DCC concept, the number of switching devices can be further reduced to construct a new unidirectional front-end rectifier (M²SCR). Comparative studies are conducted to analyze the performances of the two proposed front-end rectifiers with supportive mathematical derivations. Experimental prototypes have proven the feasibility of the proposed ac/dc/ac configurations. Results obtained show that low current harmonic distortions of 5% and high power factor of 0.99 are achieved with small input inductors despite low-switching-frequency operation at 1 kHz.