To solve the problems that the voltage stress of traditional Z-source three-level inverter capacitor is high and huge inrush current exists when starting-up

we proposed a new quasi Z-source NPC three-level inverter topology and researched its grid-connected control method.First

we analyzed the structure and working principle of the new quasi Z-source three-level neutral point clamped（NPC） inverter;then

we introduced a constant power control strategy to quasi Z-source three-level NPC inverter grid-connected system.Finally

software simulation and hardware experiment were carried out.Experimental results show that the quasi Z-source three-level NPC inverter can reduce the voltage stress of the Z-source network capacitor

andthe control method can realize the effectively tracking set values of the grid inverter output active and reactive power with low current harmonic content.