In this paper

the control strategy of NPC three-level converter at imbalance load is studied.The isolated landed-mode mathematic model is established firstly and the three-phase balance of output voltage of converter at imbalance load is achieved by way of positive and negative decoupling. Then

the modulation strategy based on decomposition of middle phase modulation is finished

the neutral point balance control of DC bus voltage is achieved on the basis of controlling independently output zero sequence voltage of converter so to assure the coordination and decoupling of the two goals. Finally

the experimental platform of NPC three-level converter at isolated imbalance load is built and the effectiveness of the coordination control strategy is verified.