Quantitative Neutral Point Voltage Balance-Based Modulated Model Predictive Control for Three-Level NPC Inverter-Fed PMSM Drive

Aiming at the defect of large fluctuation of neutral point voltage control in traditional modulated model predictive control (M2PC), an innovative M2PC based on quantitative neutral point voltage balance (QV-M2PC) is proposed in this paper. Compared with the traditional M2PC method, the proposed method makes full use of the accurate mathematical model of model predictive control to obtain a superior reference output. First, the mathematical models of the voltage change of the DC bus upper and lower capacitors are established. Then, the influence of the medium and small voltage vectors on the neutral point voltage is quantitatively considered, and the duty cycle of the positive and negative small voltage vectors is accurately adjusted. In this way, the stability of the neutral point voltage is enhanced, and its fluctuation range is reduced. Finally, through simulation, the effectiveness and superiority of the proposed control strategy is verified.