A Dual-Output NPC-Type Converter with a Model Predictive Controller with Compensation of DC Capacitor Voltage Imbalance

The dual output three-level converter is now important for several applications namely dual motor drives. The recent dual output nine-switch multilevel three-phase inverter, based on the NPC-Type structure, has been studied in open loop at nominal conditions, without closed loop control. Moreover, the dual output nine-switch multilevel inverter may present issues related to load currents control and to the unbalance of two series capacitor voltages in the dc-link. Thus, in this research work the model predictive controller (MPC) is proposed for closed loop current control, as well as for mitigation of the capacitor voltages imbalance. The MPC approach allows the minimization of a cost functional weighing two criteria, the tracking errors of the three-phase AC currents of each inverter output, as well as the two capacitors voltage imbalance. Several simulations showing the performance of the proposed control strategy are presented and discussed.