Direct power control for three-level PWM rectifier based on hysteresis strategy

This paper presents a mathematical model of three-level voltage PWM rectifier, and derives a power control model from the theory of instantaneous power. In the vector-space, the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately, then a direct power control (DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed, and a novel switching table is designed. Meanwhile, the neutral-point voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors. Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage. Moreover, the proposed method can improve the performance of the three-level rectifier.