Model Predictive Control for a Hybrid Multilevel Converter With Different Voltage Ratios

This paper proposes a model predictive control (MPC) strategy for a new hybrid multilevel converter (HMC) with different capacitor voltage ratios. The HMC provides redundant switching states, making it easy to balance the flying capacitor (FC) voltages. A discrete-time model of the HMC is built, where all the control objectives are formulated with the switching functions. The optimum switching state will be selected by evaluating all redundant switching states to minimize the cost functions. Compared with multicarrier pulsewidth modulation methods, the MPC does not require complex modulations, and the proposed HMCs can be operated with different voltage ratios to generate higher voltage levels without increasing the number of switches and FCs by using the MPC. Experimental results validate the effectiveness of the proposed control strategy for the HMCs under various operating conditions. The sensitivity of parameters is also studied with large load variations.