Modified Level-Shifted PWM Technique With Active DC Capacitors Voltages Balancing for Nine-level Packed E-Cell (PEC9) Inverter

In this paper, a modified Level-Shifted PWM technique is integrated to an active capacitor voltage balancing method to apply for the recent introduced compact single-phase multilevel converter so-called as Packed E-Cell (PEC9) topology. PEC9 is composed of a single main DC source, single auxiliary DC link including two connected capacitors in series as well as six power switch and one back-to-back switch forms bidirectional switch which nine level voltage waveforms is achievable at the output AC terminal. PEC9 benefits the advantages such as reduced component, simultaneous charging and discharging capacitors with redundant states led to have an active capacitors voltage balancing algorithm. The modified Level-Shifted PWM is integrated with active capacitor voltage balancing technique to regulate the capacitor voltage to one quarter of DC input voltage so as PEC generates nine-level voltage waveform. According to the proposed modified Level-Shifted PWM, the appropriate switching states from the redundant states are selected in the specified level which guarantees balancing PEC9 DC capacitors. The proposed modulation technique has been tested on PEC9 using Matlab/Simulink and simulation results validate its excellent performance in active DC capacitor voltage balancing.