Implementation of Model Predictive Control for Conventional Switched Capacitor Multilevel Inverter to Reduce Input Current Peak and Capacitor Voltage Ripple

With the increase in the use of renewable sources, there has been a significant topological development of multilevel inverters (MLIs). A number of MLI topologies have been developed in recent years which opens significant possibilities for further improving the robustness and efficiency of the inverter systems. Switched Capacitor Multilevel Inverter (SC-MLI) is a novel MLI structure introduced recently which requires a reduced number of power supplies in comparison with the conventional multilevel inverters. In SC-MLI, capacitors are used as alternative dc sources. Further, SCMLI possesses the voltage boosting capability and self-capacitor voltage balancing ability. One of the major limitations of SCMLI is that the input current is discontinuous and has an extremely high peak which may damage the input source and the components associated with it. Hence, the controlling of input current is required. Further, the controlling of output current of inverter, an appropriate control strategy has to be employed. For achieving these, in this paper Model Predictive Control (MPC) strategy has been implemented for basic SC-MLI unit. Extensive simulation study of 5-level SCMLI in MATLAB/Simulink shows that by using MPC, the inverter can produce the voltage levels in such way that the desired load current is achieved. Further, the peak magnitude of input current and capacitor voltage ripple are significantly reduced as compared to open loop control strategy.