Double-space vector modulation method of quasi-Z-source network direct matrix converter

The invention designs a double-space vector modulation method of a quasi-Z-source network direct matrix converter. The method comprises the following steps: 1, collecting three-phase input voltages Ua, Ub and Uc and three-phase output currents iA, iB and iC of the quasi-Z-source direct matrix converter; 2, enabling the quasi-Z-source network direct matrix converter to be equivalent to a series circuit model of a virtual rectification stage and a virtual inversion stage; 3, finding out all straight-through zero vectors by analyzing the switching state of the QZS-DMC; 4, performing space vectormodulation, and performing effective combination with 27 basic space vectors through combination selection of sectors; 5, analyzing the voltage transmission ratio; and 6, analyzing a switching time sequence, and adjusting a vector action sequence and action time, and finally, forming the double-space vector modulation method provided by the invention on the basis of ensuring the lowest switching frequency of the bidirecti