ANew Five-Level T-Type Nested Neutral Point Clamped (T-NNPC) Converter

This paper presents a new five-level T-type nested neutral point clamped (T-NNPC) converter. The proposed five-level T-NNPC topology is very attractive for medium-voltage applications as it can work in a wide range of voltages without the need of devices in series, and fewer components compared to the other five-level topologies. A model predictive control (MPC) strategy is also developed for the proposed converter to control the output currents at different output frequencies, and control flying capacitor voltages. A discrete-time model of the converter is developed and the control objectives that are the output currents and flying capacitor voltages are defined regarding switching states. A cost function is defined to minimize the deviation of the predicted values of the control objectives from their desired values. During each sampling time, the best switching state is selected and applied to the converter. The performance of the proposed five-level T-NNPC and the developed MPC strategy is studied in the MATLAB/Simulink environment, and the feasibility of the converter is evaluated experimentally.