Seven-Level Double Flying Capacitor Inverters

In this paper, four novel seven-level voltage source hybrid inverters are proposed for high-power medium-voltage. The proposed converters have less number of components in the circuit compared to the conventional 7-level topologies and all of them are double flying capacitors based. A Phase Disposition (PD) PWM strategy is employed to operate the topologies, but the flying capacitors are replaced by flying sources so that it is not necessary to use redundant states to control the capacitor voltage. This way the control scheme is more simple than the usual ones. The reduction of the component count and of the control complexity, makes them technically and economically advantageous. The features and operation of the proposed converters are analyzed and their performance are evaluated and compared by simulation results.