High resolution isolated multi-level inverter for grid-tie renewable generation system

摘要

This paper presents a 30kW grid connected multilevel inverter using isolated 3-phase transformer. The proposed power inverter is consisted by 6 IPMs and 3 isolated power transformers with 1:4:16 turn ratio and the total output voltage have 36-steps with the combination of power transformer. Each power capacity of power transformers are differently designed with the considerations of output power and design margin, and the switching frequency of each IPMs are different to get a high operating efficiency. The number of power devices of the proposed multi-level inverter is larger than the conventional one, but the operating efficiency can be much increased with distributed switching frequency algorithm. The feasibility of multi-level inverter structure and the highest proximity space vector control technology composed in this paper is verified by the computer simulation and designing and producing the experimental prototype of high resolution grid-tied multi-level inverter with 30kW renewable energy generation system.