A Model Predictive Control of Three-Level Cascaded Noninverting Buck–Boost Converter for Energy Storage System

The three-level cascaded noninverting buck–boost converter (TL-CNIBBC) has various operating modes and is especially suited at wide-range voltage bidirectional conversion for energy storage. How to choose a suitable operating mode and realize smooth mode switching is the key problem to be solved. In this article, the operation principle of TL-CNIBBC is analyzed, and two extended modes based on the traditional working modes are introduced to eliminate the dead zone when the input voltage is close to the output voltage. Second, a model predictive control (MPC) with inductor current as a cost function is proposed, taking the hysteresis loop control to avoid mode jumping with mode switching rules defined to achieve multimode smooth transition. Finally, to address the capacitor voltage imbalance in three-level converter, a modification of the duty ratio is proposed. Experimental results show the proposed control strategy can select the proper working modes effectively and realize smooth mode switching.