Research on Decomposition Sequence Feedforward Decoupling Control of Four-leg Inverter

Abstract

Three-phase four-leg inverter is currently the most efficient inversion for three-phase unbalanced and nonlinear load, this paper adopts the method of sequential feedforward decoupling control to decompose the asymmetric three-phase voltage and current into three-phase symmetrical positive, negative and zero-sequence components by symmetrical component method, each component is converted into DC variables in both positive and negative dq synchronous rotating coordinate, the voltage and current double closed PI control loop without static deviation is realized. The simulation and experiment results show that the inverter has a strong load capacity under three phase unbalanced load conditions, and the total harmonic distortion(THD) rate of each phase voltage is less than 3%, which meets the power standards and has a great value of application.