LQR Based SMC for Three-Phase-Inverter with LC Filter in Renewable Energy Conversion Systems

The 3-phase inverter is major part of the photovoltaic panels, wind energy conversion systems (WECSs) and motors which cannot be controlled without it. To dissipate uncontrolled properties as THD, reactive power and supply to the grid stable voltage it is important to control inverter in renewable energy conversion system. Usually to suppress noises in the output signal LC-filter is used in the circuit. In this paper, Sliding Mode Control (SMC) has been proposed as effective nonlinear control method. It is quite not new to synthesize SMC and LQR control methods to control the 3-phase inverter, however, the use of SMC control coupled with LQR in the inverter with LC-filter with linear and nonlinear load seems to be unique. Proposed control method is simple, robust to the disturbances and shows good performance in sense of quality of output voltage. Also, the designed load current observer which estimates load current uses only information from the inverter. Doing so, load current sensors were eliminated which makes the system cheaper and more reliable than opposite ones.