Modulation method model and optimization for cascaded H-bridge converters

A group of PNA(Pulse Net Area) variables is proposed to indicate the pulse essence of single bridge, based on which the modulation method model of cascaded H-bridge converters is established and the influencing factors on their operation characteristics are analyzed. By changing the PNA size and phase of left and right arms, the switching amount and switching loss are reduced, and all odd multiple and most even multiple harmonics of switching frequency are eliminated. Experimental results show that, the proposed model reflects the characteristics of the modulation method accurately, and the corresponding optimization strategy reduces the switching frequency and switching loss significantly and improves the quality of converter output voltage. The method is correct and feasible.