Observer Based Current Controlled Single Phase Grid Connected Inverter

Abstract

This paper describes a decoupled current control of single phase grid connected inverter achieved through d-q control via observer. The d-q control enables to set zero steady state error. Observer helps in giving a very pure in phase and quadrature components of the fundamental load current, which is being converted into d-q frame through Park transformation and used as the feed-back signal for the control system. In addition to the fundamental component the observer extracts the DC component of the grid current. Injection of these DC component into the grid has been prevented by these controller. This decoupled control has helped in controlling active and reactive components of grid current individually. Therefore by controlling the active and reactive power injected into the grid, the power factor of the grid can be improved. The Simulation study is conducted using MATLAB, considering the grid as a constant voltage source and the results are also incorporated. The performance of the control technique for sudden changes in grid voltage, variation in inductance has been shown through simulation. This control strategy enables in reducing the harmonics in current because of the observer used in feed-back.