Voltage Control of 3-Phase 4-Leg Multilevel Inverter with Minimum Number of Switching States

This paper uses a finite control set (FCS) model predictive control (MPC) technique to control the output voltage of a 3-phase 4-leg multilevel inverter with a minimum number of switching states to supply a balanced, unbalanced, or nonlinear load. Good results are obtained when using this technique for a flying-capacitor (FC) multilevel inverter with an output that includes a filter made of capacitors and inductors. In this method, 19 switching states are used instead of 81 switching states in classical inverters, reducing the time required to reach the optimal solution in the cost function (g). The cost function calculates the minimum error between the output and reference voltage by selecting the optimal switching state for driving all inverter transistors. This technique can be applied to other types of multilevel inverters without considering the type of load used or needing to adjust the controller parameters. The inverter is designed for powering the 3-phase loads by separately generating three output voltages from the fourth leg using MPC