Because zero voltage is common for all inverter outputs, the total level of output
voltage waveform becomes 2s+1. An example phase voltage waveform for a nine-level
cascaded inverter and all H-bridge cell output waveforms are shown in Fig. 2.6. In this
thesis, all dc voltage are assumed to be equal, i.e., Vdc1 =Vdc2 = =Vdc(S-1) =VdcS =Vdc ... .