A simplified PWM strategy based on MPC for NPC three-level APF systems

As a control algorithm for high performance of active power filter (APF) systems, finite control set model predictive current control (FCS-MPC) has the disadvantages of unfixed switching frequency and large amount of calculations for three-level APF systems. Therefore, in order to overcome the drawback of FCS-MPC, a simplified Pulse Width Modulation (PWM) strategy based on MPC is proposed in this paper. First, the strategy, with no rolling of all the 27 vectors, adopts the idea of a cost function to obtain the optimal reference vector of each phase. Second, the duration time of each vector in this strategy can be directly calculated by judging the sector of the virtual reference vector. Third, the neutral-point balancing problem is solved by modifying the duration time. In the meantime, the strategy is studied in detail and verified experimentally in this paper. The experiment results indicate the validity and effectiveness of the proposed strategy.