Model Predictive Control of a Five-Level Nested Neutral Point Clamped Converter

The model predictive control (MPC) is one of the promising approaches to control the multilevel converters. The main features of MPC are fast dynamic response and easy to achieve multiple control objectives with a single cost function. This paper presents a new five-level nested neutral point clamped (SL-NNPC) converter for medium-voltage, high-power applications. For reliable operation, the flying capacitor voltages of SL-NNPC topology needs to be regulated at one-fourth of the dc-link voltage along with the output current control. To achieve these objectives, an MPC approach is proposed in this paper. To implement the MPC scheme, a discrete-time model of SL-NNPC topology is developed. The control objectives of SL-NNPC are included in a cost function and evaluated for all possible switching states. The switching state which minimizes the cost function is selected and applied to the converter. The steady-state and transient performance of SL-NNPC with MPC scheme are validated through MATLAB simulations.