A novel direct power control strategy of three-level NPC rectifier without abnormal instantaneous reactive power fluctuation

A novel switching table of direct power control (DPC) strategy for three-level NPC rectifier is proposed in this paper. With the theory of instantaneous power, it gets the inner relationship between instantaneous power (active power and reactive power) and space voltage vectors. The dc-link voltages are maintained at the required level using hysteresis controller for the NP current exploiting the redundancy states of the rectifier. With the switching table proposed in this paper, the excellent dynamic and transient performances are achieved under unity power factor operation without abnormal instantaneous reactive power fluctuation. Simulation results verify the validity and feasibility of the proposed strategies.