A new 25 level multilevel asymmetrical inverter with ca-ca stage and reduced number of components

This paper proposes a new multilevel asymmetrical inverter topology based on the H-bridge topology with a bi-directional switch connected between the switches of one inverter leg and the middle point of the input DC voltages,... [ view full abstract ]

This paper proposes a new multilevel asymmetrical inverter topology based on the H-bridge topology with a bi-directional switch connected between the switches of one inverter leg and the middle point of the input DC voltages, resulting in new cell here referred as CHB-as cell. The cascaded association of two CHB-as cell with appropriate input voltage sources can provide inverter output voltage with up to 25 levels. This paper proposes the use of a HB inverter to connect the one dc source and a multiwinding transformer as a ca-ca stage to produce the asymmetrical necessary voltages to supply the two CHB-as cells. This proposal increases the converter efficiency and reduces the total number of components, maintaining low total harmonic distortion in output voltage when compared with conventional multilevel converter to produce the same number of levels at the output voltage. Simulations results for a 1 kW, 220 V with load RL are presented and validate the proposed converter with ca-ca stage using optimum switching states. This topology no need the use of any additional diode bridge.