Research On The 3-Phase 4-Leg Inverter Based On Repetitive Contorl

As to the three phase inverter, traditional three phase three legs inverter are widely used. But its three phase voltage outputs will be dissymmetrical when it supply to the three phase unbalanced loads. In allusion to this, a design which combines three phase four legs inverter,3-D SVM, repetitive control and the increasing-state-feedback control is proposed, in order to meet the purpose of achiving three phase standard output voltage as well as the ability of adapting unbalanced loads. In this article, the scheme of control will be deeply studied.At the beginning, supposing load as disturbance, increasing-sate mathematic models of the inverter inα-β-0 stator coordinate and d-q-0 rotating coordinate are established and their difference is compared. A controller combined increasing-state-feedback control and repetitive control is designed in d-q-0 rotating coordinate. By the way a 3-D SVPWM theory based on a-b-c tator coordinate is studied in this work. Then the simulation of system control and switch strategy validates consistency with the analysis using MATLAB.Finailly, A three-phase four-leg inverter of 30KVA in 220V/50HZ is designed there, including designing the program based on CCS(Code Composer studio) and print circuit boards based on DSP TMS320F2812 and selecting power electronic devices. Experimental results prove the repetive control combined increasing-state feedback control scheme in d-q-0 frame for three-phase four-leg inverter can ouput excellent three-phase AC voltage under unbalance load condition.