Abstract:Traditional three-phase grid-connected inverter has too many AC voltage sensors, which reduces the reliability of the system.In view of this, an improved voltage sensorless control strategy combined with PQ indirect current control technology is proposed, and the modeling, design steps and passive damping requirements of the output filter are discussed in detail.In the process of parameter design of the LCL filter system, the Y-type connection and the delta-type connection of the LCL filter capacitor were analyzed and designed by classification.Finally, a physical model is built to test the experimental results, and the experiment verifies the effectiveness of the proposed control strategy.