A Novel Inter-Modulated Floating Carrier Level Shifted PWM Method for PUC9 Converter

In this paper, a new level shifted pulse-width modulation (LSPWM) method utilizing the suggested intermodulated floating carrier signals is proposed for the nine-level packed U-cell (PUC9) converter. In the proposed inter-modulated floating carrier LSPWM (IFC-LSPWM) technique, six floating carrier signals are modulated between the main eight level shifted fixed carriers to achieve active voltage balancing of the auxiliary capacitors. Hence, the staircase nine-level output voltage is generated by employing eight fixed level-shifted PWM carrier signals whereas six inter-modulated floating carrier signals provide voltage balancing of the auxiliary capacitors. Therefore, the proposed IFC-LSPWM method does not require any logic gates or comparison loops to provide voltage balancing of the auxiliary capacitors. Moreover, constant switching frequency operation and the reduced values of the auxiliary capacitors are obtained by employing the proposed IFC-LSPWM. The proposed IFC-LSPWM method is applied to the three-phase PUC9 converter. The provided experimental results verify the viability and performance of the proposed IFC-LSPWM method.