Carrier Redistribution Pulsewidth Modulation for Five-Level Stacked Multicell Converter

This article presents a modified carrier redistribution pulsewidth modulation (CRPWM) method for the five-level stacked multicell converter (SMC). The proposed CRPWM method is modified by exchanging the arrangement of the carriers of phase disposition pulsewidth modulation (PDPWM). With the ingenious carrier arrangement, the proposed PWM technique equalizes the utilization of phase leg voltage redundancies corresponding to the charging and the discharging state of each floating capacitor during one switching period of all the switches. The proposed modulation strategy has the same harmonic performance of line-to-line voltage with PDPWM, while the switch utilization is the same as phase-shifted pulsewidth modulation (PSPWM). Therefore, the voltage balancing of floating capacitors is achieved during a minimum switching period even with the influence of load current change and inappropriate carrier ratio is considered. The modified CRPWM is analyzed in theory and the voltage balancing ability and output harmonics performance are compared with PSPWM and traditional CRPWM. Simulation and experimental results on the laboratory prototype five-level SMC confirm the validity of the proposed CRPWM technique.