Improved Three‐Stage Model Predictive Current Control Algorithm for Three‐Phase Three‐Level NPC Inverter

ABSTRACT This paper presents an improved three‐stage model predictive current control (MPCC) method that is proposed for three‐phase three‐level converters. The reduction of the common‐mode voltage (CMV), the effective control of the DC‐side capacitor voltage, and the reduction of the computational burden can be achieved simultaneously by the deletion of the alternative vectors in the preliminary stage and the introduction of the weighting factor in the last stage of the three‐stage voltage vector selection. Compared with other existing control strategies, this control strategy has the ability to handle multiple control objectives, simplifying the structure while reducing the number of calculations using staged selection, thus improving the performance and reliability of the inverter. The CMV is greatly reduced because the maximum CMV values of all candidate voltage vectors are limited to less than one‐sixth of the DC bus voltage. The proposed method employs an improved three‐level voltage vector selection mechanism, and it is verified through simulations and experiments that the proposed method helps to significantly reduce the computational complexity as well as reduce the DC‐side capacitor voltage fluctuations.