A novel seven-level voltage source converter for medium-voltage (MV) applications

This paper presents a novel seven-level converter for medium-voltage high-power applications. The proposed converter is based on the upgrade of the four-level nested neutral-point clamped (NNPC) converter. This converter has less number components compared to the classic seven-level converters and can operate over a wide range of voltages (2.4–7.2kV) without the need for connecting power semiconductor in series. The features and operation of the proposed converter is studied and analyzed. A sinusoidal pulse width modulation (SPWM)-based strategy is developed to employ redundant switching states and control flying capacitor voltages. The performance of the proposed converter is evaluated by simulation results.